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  • 1.
    Abbaszad Rafi, Abdolrahim
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Azarbaijan Shahid Madani University, Tabriz, Iran.
    Hamidi, N.
    Azarbaijan Shahid Madani University, Tabriz, Iran.
    Bashir-Hashemi, A.
    University of Alabama, Tuscaloosa, AL, United States.
    Mahkam, M.
    Azarbaijan Shahid Madani University, Tabriz, Iran.
    Photo-Switchable Nanomechanical Systems Comprising a Nanocontainer (Montmorillonite) and Light-Driven Molecular Jack (Azobenzene-Imidazolium Ionic Liquids) as Drug Delivery Systems; Synthesis, Characterization, and in Vitro Release Studies2018Ingår i: ACS Biomaterials Science and Engineering, ISSN 2373-9878, Vol. 4, nr 1, s. 184-192Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, photoresponsive nanomechanical systems were prepared through the intercalation of positively charged photoswitching molecular jacks (azobenzene ionic liquids, Azo-ILs) within montmorillonite (MMT) layers (MMT@Azo-ILs). The study shows that MMT@Azo-ILs are photosensitive and the synthesized molecular jacks could change the basal distances of MMT layers upon UV irradiation. These changes come from changes in the structure and geometry of Azo molecules (i.e., cis-trans isomerization) between clay layers upon UV irradiation. The prepared photoresponsive nanomechanical systems were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), field-emission scanning electron microscope (FE-SEM). Moreover, the in vitro release studies were performed in different conditions (upon UV irradiation and darkness) in pH 5.8 at 34 ± 1 °C, and it was found that the release rates from drug loaded MMT@Azo-ILs were higher upon UV irradiation in comparison with the release rates in darkness. According to the release studies, the prepared photoresponsive carriers might be considered as an excellent potential candidate in order to formulate smart sunscreens. © 2017 American Chemical Society.

  • 2.
    Afewerki, Samson
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Alimohammadzadeh, Rana
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Henshaw Osong, Sinke
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Tai, Cheuk-Wai
    The Arrhenius Laboratory, Stockholm University.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Córdova, Armando
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Eco-friendly design for scalable direct fabrication of nanocelluloseManuskript (preprint) (Övrigt vetenskapligt)
  • 3.
    Afewerki, Samson
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Alimohammadzadeh, Rana
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Osong, Sinke H.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Tai, Cheuk-Wai
    The Arrhenius Laboratory, Stockholm University.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Cordova, Armando
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Sustainable Design for the Direct Fabrication and Highly Versatile Functionalization of Nanocelluloses2017Ingår i: Global Challenges, ISSN 2056-6646, Vol. 1, nr 7, artikel-id 1700045Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study describes a novel sustainable concept for the scalable direct fabrication and functionalization of nanocellulose from wood pulp with reduced energy consumption. A central concept is the use of metal-free small organic molecules as mediators and catalysts for the production and subsequent versatile surface engineering of the cellulosic nanomaterials via organocatalysis and click chemistry. Here, “organoclick” chemistry enables the selective functionalization of nanocelluloses with different organic molecules as well as the binding of palladium ions or nanoparticles. The nanocellulosic material is also shown to function as a sustainable support for heterogeneous catalysis in modern organic synthesis (e.g., Suzuki cross-coupling transformations in water). The reported strategy not only addresses obstacles and challenges for the future utilization of nanocellulose (e.g., low moisture resistance, the need for green chemistry, and energy-intensive production) but also enables new applications for nanocellulosic materials in different areas.

  • 4.
    Afewerki, Samson
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Guangning, Ma
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Ibrahem, Ismail
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Cordova, Armando
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Highly enantioselective organo/metal cooperative catalysis for construction of spirocyclopentaneoxindoles2014Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 248, artikel-id 173-ORGNArtikel i tidskrift (Övrigt vetenskapligt)
  • 5.
    Afewerki, Samson
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap. Stockholm Univ, Berzelii Ctr EXSELENT, SE-10691 Stockholm, Sweden.
    Ma, Guangning
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Ibrahem, Ismail
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Liu, Leifeng
    Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden .
    Sun, Junliang
    Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden .
    Cordova, Armando
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap. Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden .
    Highly Enantioselective Control of Dynamic Cascade Transformations by Dual Catalysis: Asymmetric Synthesis of Polysubstituted Spirocyclic Oxindoles2015Ingår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 5, nr 2, s. 1266-1272Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The highly enantioselective (up to >99.5:0.5 er) synthesis of polysubstituted spirocyclic oxindoles with four new contiguous stereocenters, including the spiro all-carbon quaternary center, is disclosed. It is accomplished by the highly stereoselective control of a dynamic conjugate/intramolecular allylic alkylation relay sequence based on the synergistic cooperation of metal and chiral amine catalysts in which the careful selection of organic Nand, metal complex, and chiral amine is essential. The intermolecular C-C bond-forming step occurred only when both the metal and chiral amine catalysts were present.

  • 6.
    Alecrim, Viviane
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Zhang, Renyun
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Andersson, Mattias
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Exfoliated Layered Materials for Digital Fabrication2015Ingår i: NIP & Digital Fabrication Conference, 2015, Vol. 1, s. 192-194Konferensbidrag (Refereegranskat)
    Abstract [en]

    We introduced an exfoliation method of MoS2 in a 3% solution of sodium dodecyl surfactant at high concentration (i.e. 2 g/L). The bulk MoS2 was thinned by mechanical exfoliation between sand papers and the resulting powder was used to prepare dispersions by liquid exfoliation through probe sonication. The resulting dispersion consisted of very thin MoS2 nanosheets in surfactant solution with average lateral size around 126 nm. This may be interesting for applications in inkjet printed electronics.

  • 7.
    Alimadadi, Majid
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Foam-formed Fiber Networks: Manufacturing, Characterization, and Numerical Modeling: With a Note on the Orientation Behavior of Rod-like Particles in Newtonian Fluids2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Fiber networks are ubiquitous and are seen in both industrial materials (paper and nonwovens) and biological materials (plant cells and animal tissues). Nature intricately manipulates these network structures by varying their density, aggregation, and fiber orientation to create a variety of functionalities.

    In conventional papermaking, fibrous materials are dispersed in water to form a sheet of a highly oriented two-dimensional (2D) network. In such a structure, the in-plane mechanical and transport properties are very different from those in the out-of-plane direction. A three-dimensional (3D) network, however, may offer unique properties not seen in conventional paper products.

    Foam, i.e., a dispersed system of gas and liquid, is widely used as the suspending medium in different industries. Recently, foam forming was studied extensively to develop the understanding of foam-fiber interactions in order to find potential applications of this technology in papermaking.

    In this thesis, a method for producing low-density, 3D fiber networks by utilizing foam forming is investigated and the structures and mechanical properties of such networks are studied. Micro-computed tomography is used to capture the 3D structure of the network and subsequently to reproduce artificial networks. The finite element method is utilized to model the compression behavior of both the reproduced physical network and the artificial networks in order to understand how the geometry and constitutive elements of the foam-formed network affect its bulk mechanical properties. Additionally, a method was studied in order to quantify the orientation behavior of particles in a laminar Newtonian flow based on the key parameters of the flow which control the orientation.

    The resulting foam-formed structures were extremely bulky. Yet despite this high bulk, the fiber networks retained good structural integrity. The compression behavior in the thickness direction was characterized by extreme compressibility and high strain recovery after compression. The results from the modeling showed that the finite-deformation mechanical response of the fiber network in compression was satisfactorily captured by the simulation. However, the artificial network shows higher stiffness than the simulated physical network and the experiment. This discrepancy in stiffness was attributed to macroscopic structural non-uniformities in the physical network, which result in increased local compliance. It was also found that the friction between the fibers, as well as the fiber curvature, had a negligible impact on the compression response of the fiber network, while defects (in the form of kinks) had an effect on the response in the last stages of compression. The study of the orientation behavior of particles at different flow velocities, particle sizes, and channel geometries suggests that it might be possible to utilize the flow shear rate as a means to quantify the orientation behavior.

  • 8.
    Alimadadi, Majid
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Uesaka, Tetsu
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    3D-oriented fiber networks made by foam forming2016Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, ISSN 1572-882X, Vol. 23, nr 1, s. 661-671Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In industrial applications, such as paper and nonwovens, cellulose fibers are used in the form of a network where the fibers are oriented more or less in the sheet-plane direction. However, in many biological systems, fibers are instead oriented in a three-dimensional (3D) space, creating a wide variety of functionalities. In this study we created a 3D-oriented fiber network on the laboratory scale and have identified some unique features of its structure and mechanical properties. The 3D fiber network sheets were prepared by using foam-forming as well as modifying consolidation and drying procedures. The fiber orientation and tensile/compression behavior were determined. The resulting sheets were extremely bulky (above 190 cm3/g) and had extremely low stiffness (or high softness) compared to the reference handsheets. Despite this high bulk, the sheets retained good structural integrity. We found that a 3D-oriented fiber network requires much less fiber-fiber contact to create a connected (“percolated”) network than a two-dimensionally oriented network. The compression behavior in the thickness direction was also unique, characterized by extreme compressibility because of its extreme bulk and a long initial increase in the compression load as well as high strain recovery after compression because of its fiber reorientation during compression.

  • 9.
    Alimadadi, Majid
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Uesaka, Tetsu
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Exploring One-more Dimension of Paper: Properties of 3D-Orieneted Fiber Network2014Ingår i: Progress in Paper Physics Proceedings 2014, 2014Konferensbidrag (Övrigt vetenskapligt)
  • 10.
    Alimohammadzadeh, Rana
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Osong, Sinke H.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Cordova, Armando
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Scalable Improvement of the Strength Properties of Chemimechanical Pulp Fibers by Eco-Friendly Catalysis2018Ingår i: IMPC 2018, Trondheim, Norway, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    The sustainable improvement of the strength properties of chemimechanical pulp by eco-friendlycatalysis is disclosed. Significant research activities have been performed on the use of cationic starchand polyelectrolyte complexes for improving the strength properties of cellulose-based materials. Herewe apply an eco-friendly strategy based on catalysis for significantly improving the strength propertiesof sheets made from chemimechanical pulp (CTMP) and bleeched sulphite pulp (BSP) using sustainablepolyelectrolyte complexes as the strength additives and organocatalysis. This surface engineeringstrategy significantly increased the strength properties of the assembled sheets (up to 100% in the caseof Z-strength). We also developed a catalytic selective colour marking of the cationic potato starch (CS)and carboxymethylcellulose (CMC) in order to elucidated how the specific strength additives aredistributed on the sheets. It revealed that the strength additives were more evenly distributed on thesheets made from CTMP as compared to BSP sheets. This is most likely attributed to the presence oflignin in the former lignocellulosic material. It also contributes to the increase in strength (up to 100%,Z-strength) for the CTMP derived sheets. The selective colour marking method also revealed that morestrength additives had been bound to the pulps in the presence of the catalyst.

  • 11.
    Alves, L.
    et al.
    University of Coimbra, Department of Chemistry, Coimbra, Portugal .
    Medronho, B.
    Faculty of Sciences and Technology, Centre for Mediterranean Bioresources and Food, University of Algarve, Ed. 8, Campus de Gambelas, Faro, Portugal .
    Antunes, F. E.
    University of Coimbra, Department of Chemistry, Coimbra, Portugal .
    Fernández-García, M. P.
    IFIMUP and in - Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, Faculty of Science, University of Porto, Porto, Portugal .
    Ventura, J.
    IFIMUP and in - Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, Faculty of Science, University of Porto, Porto, Portugal .
    Araújo, J. P.
    IFIMUP and in - Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, Faculty of Science, University of Porto, Porto, Portugal .
    Romano, A.
    Faculty of Sciences and Technology, Centre for Mediterranean Bioresources and Food, University of Algarve, Ed. 8, Campus de Gambelas, Faro, Portugal .
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore .
    Unusual extraction and characterization of nanocrystalline cellulose from cellulose derivatives2015Ingår i: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 210, s. 106-112Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Unlike many nanomaterials, nanocrystalline cellulose (CNC) is not synthesized from molecular or atomic components but rather extracted from naturally occurring cellulose. Undoubtedly, the exploitation of CNCs will become a bridge between nanoscience and natural resource products, which could play a major role in reviving the forest industry. In this work, CNC was successfully extracted from unusual sources, hydroxypropyl methylcellulose (HPMC) and carboxymethylcellulose (CMC). The extracted crystallites were purified and further characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and dynamic light scattering (DLS). The average size of the CNCs extracted from HPMC and CMC was found to be less (and with lower zeta potential) than the ones extracted from microcrystalline cellulose (MCC). On the other hand, FTIR and XRD revealed that native HPMC and CMC are unexpectedly highly crystalline and hence can be used as a source for CNCs. © 2014 Elsevier B.V.All rights reserved.

  • 12.
    Alves, Luis
    et al.
    CQC, University of Coimbra, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. CQC, University of Coimbra, Portugal; Lund University.
    Klotz, Björn
    BASF Personal Care and Nutrition GmbH, Düsseldorf, Germany.
    Böttcher, Axel
    BASF Personal Care and Nutrition GmbH, Düsseldorf, Germany.
    Haake, Hans-Martin
    BASF Personal Care and Nutrition GmbH, Düsseldorf, Germany.
    Antunes, Filipe E.
    CQC, University of Coimbra, Portugal.
    On the rheology of mixed systems of hydrophobically modified polyacrylate microgels and surfactants: Role of the surfactant architecture2018Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 513, s. 489-496Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hypothesis The rheological control of suspensions is of key interest in the formulation design. A chemically cross-linked hydrophobically modified poly(acrylic acid) (HMCL-PAA), used as rheology modifier, is pH sensitive and shows swelling behavior above a critical pH due to the ionization of the acrylic acid groups. At low pH, HMCL-PAA suspensions are liquid and turbid. The binding of surfactants to HMCL-PAA, at low pH conditions, can result in significant changes on rheology and transparency of the polymeric suspensions, due to the swelling of the microgel particles. Experiments The influence of surfactants addition on the rheological properties and transparency of HMCL-PAA suspensions was determined. A systematic study was performed using different types of surfactants (ionic, non-ionic and zwitterionic). Findings The gelation efficiency of HMCL-PAA suspensions at low pH is strongly dependent on surfactant architecture: ionic surfactants are found to be much more efficient than non-ionic or zwitterionic surfactants. Ionic surfactants lead to a liquid-to-gel transition accompanied by an increase of transparency of the suspensions. Among the ionic surfactants, anionics show stronger interactions with the polymer. Also the surfactant hydrophobicity is relevant; the more hydrophobic the surfactant, the stronger is the binding to the polymer and thus the larger the particle swelling. 

  • 13.
    Alves, Luis
    et al.
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal..
    Medronho, Bruno
    Univ Algarve, Fac Sci & Technol MEDITBIO, Campus Gambelas,Ed 8, P-8005139 Faro, Portugal..
    Antunes, Filipe E.
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal..
    Topgaard, Daniel
    Lund Univ, Ctr Chem & Chem Engn, Dept Chem, Div Phys Chem, S-22100 Lund, Sweden..
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Nanyang Technol Univ, Mat Sci & Engn, Singapore 639798, Singapore.
    Dissolution state of cellulose in aqueous systems. 1. Alkaline solvents2016Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, nr 1, s. 247-258Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The understanding of the state of dissolution of cellulose in a certain solvent is a critical step forward in the development of new efficient solvent systems for cellulose. Nevertheless, obtaining such information is not trivial. Recently, polarization transfer solid-state NMR (PTssNMR) was shown to be a very promising technique regarding an efficient and robust characterization of the solution state of cellulose. In the present study, combining PTssNMR, microscopic techniques and X-ray diffraction, a set of alkaline aqueous systems are investigated. The addition of specific additives, such as urea or thiourea, to aqueous NaOH based systems as well as the use of an amphiphilic organic cation, is found to have pronounced effects on the dissolution efficiency of cellulose. Additionally, the characteristics of the regenerated material are strongly dependent on the dissolution system; typically less crystalline materials, presenting smoother morphologies, are obtained when amphiphilic solvents or additives are used.

  • 14.
    Alves, Luis
    et al.
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal..
    Medronho, Bruno
    Univ Algarve, Fac Sci & Technol MEDITBIO, Campus Gambelas,Ed 8, P-8005139 Faro, Portugal..
    Antunes, Filipe E.
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal..
    Topgaard, Daniel
    Lund Univ, Ctr Chem & Chem Engn, Dept Chem, Div Phys Chem, SE-22100 Lund, Sweden..
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Nanyang Technol Univ, Mat Sci & Engn, Singapore 639798, Singapore.
    Dissolution state of cellulose in aqueous systems. 2. Acidic solvents2016Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 151, s. 707-715Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose is insoluble in water but can be dissolved in strong acidic or alkaline conditions. How well dissolved cellulose is in solution and how it organizes are key questions often neglected in literature. The typical low pH required for dissolving cellulose in acidic solvents limits the use of typical characterization techniques. In this respect, Polarization Transfer Solid State NMR (PT ssNMR) emerges as a reliable alternative. In this work, combining PT ssNMR, microscopic techniques and X-ray diffraction, a set of different acidic systems (phosphoric acid/water, sulfuric acid/glycerol and zinc chloride/water) is investigated. The studied solvent systems are capable to efficiently dissolve cellulose, although degradation occurs to some extent. PT ssNMR is capable to identify the liquid and solid fractions of cellulose, the degradation products and it is also sensitive to gelation. The materials regenerated from the acidic dopes were found to be highly sensitive to the solvent system and to the presence of amphiphilic additives in solution.

  • 15.
    Andersson, Henrik
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Manuilskiy, Anatoliy
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Lidenmark, Cecilia
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Gao, Jinlan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    Öhlund, Thomas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Örtegren, Jonas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Schmidt, Wolfgang
    Schoeller Technocell GmbH and Co. KG, Burg Gretesch, D-49086, Osnabrück, Germany.
    Nilsson, Hans-Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för elektronikkonstruktion.
    The influence of paper coating content on room temperature sintering of silver nanoparticle ink2013Ingår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 24, nr 45, s. Art. no. 455203-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The resistance of inkjet printed lines using a silver nanoparticle based ink can be very dependent on the substrate. A very large difference in resistivity was observed for tracks printed on paper substrates with aluminum oxide based coatings compared to silica based coatings. Silica based coatings are often cationized with polymers using chloride as a counter ion. It is suggested that the precipitation of silver salts is the cause of the high resistivity, since papers pretreated with salt solutions containing ions that precipitate silver salts gave a high resistance. Silver nitrate has a high solubility and paper pretreated with nitrate ions gave a low resistivity without sintering. The results obtained show that, by choosing the correct type of paper substrate, it is possible to manufacture printed structures, such as interconnects on paper, without the need for, or at least to reduce the need for, post-print sintering. This phenomenon is, of course, ink specific. Inks without or with a low silver ion content are not expected to behave in this manner. In some sensor applications, a high resistivity is desired and, by using the correct combination of ink and paper, these types of sensors can be facilitated.

  • 16.
    Andersson, K.
    et al.
    Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Box 102, SE-23053 Alnarp, Sweden.
    Bergman, K. -O
    IFM Biology, Conservation Ecology Group, Linköping University, SE-58183 Linköping, Sweden.
    Andersson, Fredrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Jansson, N.
    IFM Biology, Conservation Ecology Group, Linköping University, SE-58183 Linköping, Sweden.
    Burman, J.
    Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Box 102, SE-23053 Alnarp, Sweden.
    Winde, I.
    Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Box 102, SE-23053 Alnarp, Sweden.
    Larsson, M. C.
    Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Box 102, SE-23053 Alnarp, Sweden.
    Milberg, P.
    IFM Biology, Conservation Ecology Group, Linköping University, SE-58183 Linköping, Sweden.
    High-accuracy sampling of saproxylic diversity indicators at regional scales with pheromones: The case of Elater ferrugineus (Coleoptera, Elateridae)2014Ingår i: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 171, s. 156-166Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The rare beetle Elater ferrugineus was sampled at 47 sites in the county of Östergötland, Sweden by means of pheromone-baited traps to assess its value as an indicator species for hollow oak stands rich in rare saproxylic beetle species. In addition, Osmoderma eremita was also sampled with pheromone baits. These data were then compared against species survey data collected at the same sites by pitfall and window traps. Both species co-occur with many Red Listed saproxylic beetles, with E. ferrugineus being a somewhat better indicator for the rarest species. The conservation value of a site (measured as Red List points or number of Red Listed species) increased with the number of specimens of E. ferrugineus and O. eremita caught. Accuracy of sampling by means of pheromone trapping turned out to be radically different for the two model species. E. ferrugineus traps put out during July obtained full accuracy after only 6. days, whereas O. eremita traps needed to be out from early July to mid-August in order to obtain full accuracy with one trap per site. By using E. ferrugineus, or preferably both species, as indicator species, accuracy would increase and costs decrease for saproxylic biodiversity sampling, monitoring and identification of hotspots. © 2014 Elsevier Ltd.

  • 17.
    Andersson, Mari
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Willner, Sara
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Förluster i solfångare Avsvalning av rörsystemet i solfångarfält2014Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 18.
    Andersson, Mikael
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Volymberäkning med temperaturgrund: Beräkning av volymändringen i ackumulatortanken med hänsyn till nätets volymändring utifrån temperatur2017Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta arbete har utförts på uppdrag givet av Sundsvall Energi AB med syftet att skapa en koppling mellan Sundsvall Energi AB:s ackumulator i Granloholm och stadsnätet med temperatur- och därmed volymbas, samt använda denna koppling för att få en bättre förståelse för deras läckage.

    Under Projektets gång genomfördes en litteraturstudie och en undersökning av företagets nuvarande system, för att få en förståelse över systemet och uppdraget. Avsaknaden av liknande arbeten tvingade mig att titta på läckage detektionsmetoder som var relevanta även fast de inte hanterade samma område helt och hållet. Handledarna och personal på plats hjälpte däremot till med att få fram den information som efterfrågades samt gav råd och tips om aspekter angående uppdraget som inte hade tagits i betänkande tidigare.

    Modellen utvecklades fram bit för bit under arbetes period, då inget annat arbete hittades som kunde ge någon riktig ram för arbetet. Modellen har visat sig vara noggrannare än dess företrädare men också svårare att implementera då den behöver behandla mycket mer indata.  

    Examensarbetet har visat hur annorlunda energisystem kan vara från varandra och hur olika, de olika metoderna som finns att titta och åtgärda problem i systemet är. Användning av existerande mätare och instrument är inte alltid pålitligt eller tillgängligt och antaganden och föreklingar måste ibland göras för att få en översiktsbild och en fungerande grund att utgå ifrån.

  • 19.
    Andres, Britta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Cellulose binders for electric double-layer capacitor electrodes: The influence of cellulose quality on electrical properties2018Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 141, s. 342-349Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose derivatives are widely used as binders and dispersing agents in different applications. Binders composed of cellulose are an environmentally friendly alternative to oil-based polymer binding agents. Previously, we reported the use of cellulose nanofibers (CNFs) as binders in electrodes for electric double-layer capacitors (EDLCs). In addition to good mechanical stability, we demonstrated that CNFs enhanced the electrical performance of the electrodes. However, cellulose fibers can cover a broad range of length scales, and the quality requirements from an electrode perspective have not been thoroughly investigated. To evaluate the influence of fiber quality on electrode properties, we tested seven samples with different fiber dimensions that are based on the same kraft pulp. To capture the length scale from fibers to nanofibrils, we evaluated the performance of the untreated kraft pulp, refined fibers, microfibrillated cellulose (MFC) and CNFs. Electrodes with kraft pulp or refined fibers showed the lowest electrical resistivity. The specific capacitances of all EDLCs were surprisingly similar, but slightly lower for the EDLC with CNFs. The same electrode sample with CNFs also showed a slightly higher equivalent series resistance (ESR), compared to those of the other EDLCs. Graphite dispersions with MFC showed the best dispersion stability. 

  • 20.
    Andres, Britta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engström, Ann-Christine
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Cellulose-based binder systems for electrochemical electrodes2015Konferensbidrag (Övrigt vetenskapligt)
  • 21.
    Andres, Britta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Engström, Ann-Christine
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Electrode Mass Balancing as an Inexpensive and Simple Method to Increase the Capacitance of Electric Double-Layer Capacitors2016Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, nr 9, s. 1-12, artikel-id e0163146Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Symmetric electric double-layer capacitors (EDLCs) have equal masses of the same active material in both electrodes. However, having equal electrode masses may prevent the EDLC to have the largest possible specific capacitance if the sizes of the hydrated anions and cations in the electrolyte differ because the electrodes and the electrolyte may not be completely utilized. Here we demonstrate how this issue can be resolved by mass balancing. If the electrode masses are adjusted according to the size of the ions, one can easily increase an EDLC's specific capacitance. To that end, we performed galvanostatic cycling to measure the capacitances of symmetric EDLCs with different electrode mass ratios using four aqueous electrolytes-Na2SO4, H2SO4, NaOH, and KOH (all with a concentration of 1 M)-and compared these to the theoretical optimal electrode mass ratio that we calculated using the sizes of the hydrated ions. Both the theoretical and experimental values revealed lower-than-1 optimal electrode ratios for all electrolytes except KOH. The largest increase in capacitance was obtained for EDLCs with NaOH as electrolyte. Specifically, we demonstrate an increase of the specific capacitance by 8.6% by adjusting the electrode mass ratio from 1 to 0.86. Our findings demonstrate that electrode mass balancing is a simple and inexpensive method to increase the capacitance of EDLCs. Furthermore, our results imply that one can reduce the amount of unused material in EDLCs and thus decrease their weight, volume and cost.

  • 22.
    Andres, Britta
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Blomquist, Nicklas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Enhanced electrical and mechanical properties of nanographite electrodes for supercapacitors by addition of nanofibrillated cellulose2014Ingår i: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 251, nr 12, s. 2581-2586Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Graphene and porous carbon materials are widely used as electrodes in supercapacitors. In order to form mechanically stable electrodes, binders can be added to the conducting electrode material. However, most bindersdegrade the electrical performance of the electrodes. Here we show that by using nanofibrillated cellulose(NFC) as binder the electrical properties, such as capacitance, were enhanced. The highest capacitance was measured at a NFC content of approximately 10% in ratio to the total amount of active material. NFC is a good ionconductor and improves the access of ions in the electrodes. Thus, electrodes made of a mixture of nanographite and NFC achieved larger capacitances in supercapacitors than electrodes with nanographite only. In addition to electrical properties, NFC enhanced the mechanical stability and wet strength of the electrodes significantly. Furthermore, NFC stabilized the aqueous nanographite dispersions, which improved the processability. Galvanostatic cycling was performed and an initial transient behaviour of the supercapacitors during the first cycles was observed. However, stabilized supercapacitors showed efficiencies of 98–100 %.

  • 23.
    Becher, Paul G.
    et al.
    Swedish University of Agricultural Sciences, Alnarp.
    Lebreton, Sebastien
    Swedish University of Agricultural Sciences, Alnarp.
    Wallin, Erika
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Borrero, Felipe
    Colombian Corporation of Agricultural Research, Las Palmas, Bogota, Colombia.
    Bengtsson, Marie
    Swedish University of Agricultural Sciences, Alnarp.
    Joerger, Volker
    Staatliches Weinbauinstitut, Freiburg, Germany.
    Witzgall, Peter
    Swedish University of Agricultural Sciences, Alnarp.
    The Scent of the Fly2018Ingår i: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 44, nr 5, s. 431-435Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    (Z)-4-undecenal (Z4-11Al) is the volatile pheromone produced by females of the vinegar fly Drosophila melanogaster. Female flies emit Z4-11Al for species-specific communication and mate-finding. A sensory panel finds that synthetic Z4-11Al has a characteristic flavour, which can be perceived even at the small amounts produced by a single female fly. Since only females produce Z4-11Al, and not males, we can reliably distinguish between single D. melanogaster males and females, according to their scent. Females release Z4-11Al at 2.4 ng/h and we readily sense 1 ng synthetic Z4-11Al in a glass of wine (0.03 nmol/L), while a tenfold concentration is perceived as a loud off-flavour. This corroborates the observation that a glass of wine is spoilt by a single D. melanogaster fly falling into it, which we here show is caused by Z4-11Al. The biological role of Z4-11Al or structurally related aldehydes in humans and the basis for this semiochemical convergence remains yet unclear. 

  • 24.
    Berg, Jan-Erik
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Sandberg, Christer
    Braviken Paper Mill, Holmen Paper, SE-60188 Norrkoping, Sweden.
    Engberg, Birgitta A.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Low-consistency refining of mechanical pulp in the light of forces on fibres2015Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, nr 2, s. 225-229Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this investigation was to find new approaches to evaluate the performance of low-consistency refiners. Data from a paper mill producing TMP from Norway spruce was used in order to find a possible way to calculate the power split between the zones in a TwinFlo refiner. An assumption of equal amount of fibres captured between overlapping bars was found successful in order to develop equations for the power split. The equations predicted equal power in both zones at equal disc gaps. The power was found to increase approximately linearly with decreasing disc gap over the range, 0.1-0.2 mm. The power split was essential to know for calculating refining intensities expressed as specific edge load and forces on fibres in the two zones. The reduction in fibre length was about 5% at 0.17 mm disc gap or at 0.03 N forces on fibres or at 0.7 J/m specific edge load. Disc gap, forces on fibres and specific edge load was found to predict fibre shortening approximately equally upon changes in power and flow rate through the refiner.

  • 25.
    Berg, Jan-Erik
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Sandberg, Christer
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Holmen Paper, Braviken Paper Mill, Sweden.
    Engberg, Birgitta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    LC Refining Intensity In The Light Of Forces On Fibres2014Ingår i: International Mechanical Pulping Conference, IMPC 2014, Espoo: Paper Engineers' Association (PI) , 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of this investigation was to find new approaches to evaluate the performance of a full sized two-zoned low-consistency refiner i.e. a refiner with two stators and one rotor in between. Data from a paper mill producing TMP from Norway spruce was used in order to find a possible way to calculate the power split between the two zones. An assumption of equal amount of fibres captured between overlapping bars was found successful in order to develop equations for the power split. The equations predicted equal power in both zones at equal disc gaps. The power was found to correlate approximately linearly with the disc gap. The power split was essential to know for calculating refining intensity expressed as specific edge load and forces on fibres in the two zones. The reduction in fibre length was about 5% at 0.17 mm disc gap corresponding to 0.03 N force on fibres and 0.7 J/m specific edge load. Disc gap, force on fibres and specific edge load was found to predict the fibre shortening with approximately equal sufficiency upon changes in power and flow rate through the refiner.

  • 26.
    Bergström, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Modelling Mechanics of Fibre Network using Discrete Element Method2018Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Low-density fibre networks are a fundamental structural framework of everyday hygiene products, such as baby diapers, incontinence and feminine care products, bathroom tissue and kitchen towels. These networks are a random assembly of fibres, loosely bonded and oriented in the plane direction.

    Designing such a complex network structure for better performance, better use of materials and lower cost is a constant challenge for product designers, requiring in-depth knowledge and understanding of the structure and properties on the particle (fibre) level.

    This thesis concerns the development of a computational design platform that will generate low-density fibre networks and test their properties, seamlessly, with the aim to deepening the fundamental understanding of the micromechanics of this class of fibre networks.

    To achieve this goal, we have used a particle-based method, the Discrete Element Method (DEM), to model the fibres and fibre networks. A fibre is modelled as a series of linked beads, so that one can consider both its axial properties (stretching and bending) and transverse properties (shearing,twisting and transverse compression). For manufacturing simulations, we developed the models for depositing fibres to form a fibre network, consolidating the fibre network, compressing to make a 3D-structured network, and creating creping. For testing the end-use performance, we have developed two models and investigated the micromechanics of the fibre network in uniaxial compression in the thickness direction (ZD) and in uniaxial tension in the in-plane direction.

    In the ZD-uniaxial compression of entangled (unbonded) fibrenetworks, the compression stress exhibits a power-law relationship with density, with a threshold density. During compression, the fibre deformation mode changed from fibre bending to the transverse compression of fibre. Accordingly, the transverse properties of the fibreshad a large impact on the constitutive relation. By considering a realistic value for the transverse fibre property, we were able to predict the valuesof the exponent widely observed in the experimental literature. We havefound that the deviation of the experimental values from those predictions by the earlier theoretical studies is due to the neglect of the transverse fibre property.

    For tensile properties of bonded networks, we have investigated scaling of network strength with density and fibre–fibre bond strength. The network strength showed beautiful scaling behaviour with both density and bond strength, with exponents 1.88 and 1.08 respectively. The elastic modulus of the network, on the other hand, showed a changing exponent(from 2.16 to 1.69) with density in accordance with previous results in the literature. We have also reconfirmed that, with increasing density, the deformation mode changes from bending to stretching. The predicted results for both elastic modulus and strength agreed very well with experimental data of fibre networks of varying densities reported in the literature.

    We have developed a computational platform, based on DEM, for accurately modelling a fibre network from its manufacturing process to product properties. This is a tool that allows a versatile design of materials and products used for hygiene products, providing a promising venue for exploring the parameter space of new material and process design.

  • 27.
    Boija, Susanne
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    On metal ion chelates and conditional stability constant determination: Method development and selective ion flotation of chelating surfactants2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 28.
    Boija, Susanne
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Almesåker, Ann
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Determination of conditional stability constants for some divalent transition metal ion-EDTA complexes by electrospray ionization mass spectrometry2014Ingår i: Journal of Mass Spectrometry, ISSN 1076-5174, E-ISSN 1096-9888, Vol. 49, nr 7, s. 550-556Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Conditional stability constants of coordination complexes comprising divalent transition metals, Cu2+, Ni2+, Zn2+, Co2+, and ethylenediaminetetraacetic acid (EDTA) were determined utilizing electrospray ionization mass spectrometry. The deviation of signal response of a reference complex was monitored at addition of a second metal ion. The conditional stability constant for the competing metal was then determined through solution equilibria equations. The method showed to be applicable to a system where Co2+ and Zn2+ competed for EDTA at pH 5. When Cu2+ and Ni2+ competed for EDTA, the equilibrium changed over time. This change was shown to be affected in rate and size by the type of organic solvent added. In this work, 30% of either methanol or acetonitrile was used. It was found that if calibration curves are prepared for both metal complexes in solution and the measurements are repeated with sufficient time space, any change in equilibrium of sample solutions will be discovered. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

  • 29.
    Breitkreuz, Rikard
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Ackumulering av ånga: Effektivare ångproduktion vid Akzo Nobel Stockvik2017Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Rapporten avser att undersöka om det finns möjlighet att installera en ång-ackumulator på ångcentralen på Akzo Nobel Stockviksamt att dimensionera ackumulatorn. Ackumulatorns syfte är att jämna ut ångproduktionen då det finns ett intermittent behov av ånga hos ångcentralens kunder.

    Inom site Stockvik finns internt bränsle i form av CO-gas och vätgas att tillgå för förbränning i ångcentralens pannor, att använda internt bränsle är både en ekonomisk och miljömässig fördel. Vid stora ånguttag räcker inte interna bräns-len till och olja måste användas som stödbränsle. En ackumulator kan ackumu-lera ånga för att ersätta de tillfällen där olja måste eldas. 

    Energikartläggning visar att de två största förbrukarna av ånga även står för störst momentana uttag av ånga vilket medför ett behov av stödeldning med olja i panna 3. Detta visar på ett utrymme för en ackumulator i systemet.

    Ackumulatorn kan placeras i närhet till ångcentralen vilket minskar energiför-luster. Tre ackumulatorer har tagits fram utifrån en bedömning av genomsnittlig överskottseffekt, ackumulatorerna har totala volymerna 29, 70 samt 112m3. Stora mängder data från processen finns sparat i system hos Akzo Nobel, detta har nyttjats för att jämföra de olika ackumulatorerna mot produktionen 2015 och 2016.

    Lönsamheten är densamma oberoende på val av ackumulator men investerings-kostnaden stiger med ökad volym. Snabbast återbetalningstid 4,4 år, har en ack-umulator av 29 m3.Miljömässiga fördelar oberoende på val av ackumulator är minskad oljeanvändning med ca 350 m3/år vilket medför sänkt koldioxidutsläpp

  • 30.
    Chen, Xu
    et al.
    State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, China.
    Yang, Haiping
    State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, China.
    Chen, Yingquan
    State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, China.
    Chen, Wei
    State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, China.
    Lei, Tingzhou
    Henan Academy of Sciences Institute of Energy Co., Ltd, Zhengzhou, Henan, China.
    Zhang, Wennan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Chen, Hanping
    State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, China.
    Catalytic fast pyrolysis of biomass to produce furfural using heterogeneous catalysts2017Ingår i: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 127, s. 292-298Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Furfural is a valuable chemical, the production of furfural from renewable biomass resources becomes more attractive in recent years. In this study, biomass fast pyrolysis with heterogeneous catalysts (titanium compounds (TiN, TiO2 and TiOSO4) and metal nitrides (MoN, GaN and VN)) for furfural production was investigated experimentally by means of pyrolysis-gas chromatography/mass-spectrometry (Py-GC/MS). The measurement results indicated that TiN and GaN promoted the furfural compounds production notably mainly through direct decomposition of oligosaccharides. The formation of furfural was promoted when the amount of TiN was increased, and the yield of furfural formed was about 5.5 times the size of that from non-catalytic pyrolysis when TiN/cellulose mass ratio was 4. The furfural yield decreased when the pyrolysis residence time increased from 10 to 30 s, which suggests competitive reactions (formation of 1, 6-anhydro-beta.-D-glucopyranose) against the formation of furfural. TiN, as a catalyst for fast pyrolysis towards furfural production, can be well applied to agriculture biomass residues. Comparing three biomass residues: corncob, wheat straw and cotton stalk, corncob showed higher furfural yield due to the higher holocellulose content, while wheat straw showed higher furfural selectivity. 

  • 31.
    Cuomo, Francesca
    et al.
    Univ Molise, Campobasso, Italy.
    Cofelice, Martina
    Univ Molise, Campobasso, Italy.
    Venditti, Francesco
    Univ Molise, Campobasso, Italy.
    Ceglie, Andrea
    Univ Molise, Campobasso, Italy.
    Miguel, Maria
    Coimbra Univ, Coimbra, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Lund Univ, Lund.
    Lopez, Francesco
    Univ Molise, Campobasso, Italy.
    In-vitro digestion of curcumin loaded chitosan-coated liposomes2018Ingår i: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 168, s. 29-34Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Liposomes are considered a major route for encapsulation of hydrophilic and hydrophobic molecules. Chitosan coated liposomes could represent an alternative way as a carrier for delivery of drugs in human body. In this study the preparation and applicability of chitosan-coated liposomes containing curcumin as well as curcumin loaded anionic liposomes were evaluated. The applicability of the carriers was tested by means of an in vitro digestion procedure allowing for measurement of the bioaccessibility of ingested curcumin. Values of diameter, polydispersity index and surface charge for curcumin loaded anionic liposomes obtained through dynamic light scattering and zeta-potential measurements were 129 nm, 0.095 and -49 mV, respectively. After chitosan-coating, diameter and polydispersity index remain unvaried while the surface charge gets positive. Slightly higher curcumin concentrations were found after the mouth and the stomach digestion phases when curcumin was loaded in anionic liposomes. On the contrary, after the intestinal phase, a higher percentage of curcumin was found when chitosan-coated liposomes were used as carrier, both in the raw digesta and in the bile salt micellar phase. It was shown that the presence of a positively charged surface allows a better absorption of curcumin in the small intestine phase, which increases the overall curcumin bioavailability. The mechanism behind these results can be understood from the composition of different environments generated by the digestive fluids that differently interact with anionic or cationic surfaces. 

  • 32.
    Cuomo, Francesca
    et al.
    Univ Molise, Dipartimento Agr, Ambiente Alimenti DIAAA, I-86100 Campobasso, Italy.
    Lopez, Francesco
    Univ Molise, Dipartimento Agr, Ambiente Alimenti DIAAA, I-86100 Campobasso, Italy.
    Piludu, Marco
    Univ Cagliari, Dipartimento Sci Biomed, I-09042 Monserrato, CA, Italy.
    Miguel, Maria G.
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Lund Univ, Phys Chem, S-22100 Lund, Sweden.
    Ceglie, Andrea
    Univ Molise, Dipartimento Agr, Ambiente Alimenti DIAAA, I-86100 Campobasso, Italy.
    Release of small hydrophilic molecules from polyelectrolyte capsules: Effect of the wall thickness2015Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 447, s. 211-216Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polymer nanocapsules assembled on cationic liposomes have been built through the layer-by-layer (LbL) technique. Chitosan and alginate, two biocompatible polyelectrolytes, were used to cover the template, where the Rhodamine B was previously loaded. The multishell formed with the alternate deposition of the polyelectrolytes, according to the principles of the LbL assembly, was supposed to change the permeability of the capsule wall. The thickness of the multishell was seen increasing with the number of layers deposited through the observations with the Transmission Electron Microscope. The permeability of the capsules was studied through Rhodamine B release assays. Nanocapsules with seven layers of polyelectrolytes released the dye slowly compared to the capsules with three or five layers. The Ritger-Peppas model was applied to investigate the release mechanisms and a non-Fickian transport behavior was detected regardless of the number of layers. Values of diffusion coefficients of Rhodamine B through the capsule wall were also calculated. (C) 2014 Elsevier Inc. All rights reserved.

  • 33.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Sample Preparation Using Argon Ion Beam Milling2013Ingår i: Argon: Production, Characteristics and Applications / [ed] Bogos Nubar Sismanoglu, Homero Santiago Maciel, Marija Radmilovic-Radjenovic, Rodrigo Savio Pessoa (Physics Department, Lab of Optics and Spectroscopy, Lab of Plasmas and Processes and Lab of Mechanics, Heath and Waves, Technological Institute of Aeronaut, Hauppauge, NY: Nova Science Publishers, Inc., 2013, s. 223-240Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Surface and cross section analysis can provide important information on material properties. It has, however, been difficult to characterise the internal structure at a micro scale using cross sections prepared with conventional methods, such as e.g. mechanical grinding and polishing, because these procedures can damage the surface and introduce artefacts. A few years ago, a new precision argon ion beam cross section polisher was shown to be a suitable sample preparation technique for microstructure characterisation. It produces high quality cross sections free from artefacts and distortions. This technique can be used for cross section preparation of a wide variety of materials including composites, metals, ceramics and polymers. Argon ion beam milling can also be used in combination with focused ion beam (FIB) as a final step to remove FIB-damaged layers before nano- and microstructure characterisation in high resolution transmission electron microscopy (HRTEM).

  • 34.
    Dahlström, Christina
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Faria, Gregorio C
    Department of Materials Science and Engineering, Stanford University, São Carlos Physics Institute, University of São Paulo.
    Engström, Ann-Christine
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Duong, Duc, T.
    Department of Materials Science and Engineering, Stanford University.
    Salleo, Alberto
    Department of Materials Science and Engineering, Stanford University.
    Structural Change of Cellulose Nanofibers in Supercapacitor Electrodes during Galvanostatic Cycling2015Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Graphene and other carbon-based materials are often used as electrodes in electrochemical double-layer supercapacitors (EDLCs), due to their ability to store electrical energy. Cellulose nanofibers (CNF) have been proven to be suitable as a dispersion agent and binder in graphite based electrodes for supercapacitor applications, especially due to their capability to improve the wet and dry strength of the electrode. At the same time the capacitance is maintained or even increased with addition of CNF. It is reasonable to believe that the addition of CNF manages to stabilize smaller graphite particles in the dispersion which results in larger internal surface area in the dry material.

     

    When the amount of CNF is around 20 wt%, (in ratio to the total mass of active material), both scanning electron microscopy and XPS analysis showed that the surface is almost completely covered with the nano-cellulose. Even with this isolating layer of cellulose it is interesting to note that the capacitance is as high as 90 F/g, compared to around 50 F/g for the lowest CNF amount of 5 wt%. However, by applying voltage pulses during the galvanostatic cycling procedure for capacitance measurements, an initial transient behavior is observed during the first cycles. Therefore the capacitance is calculated after 4000 charge and discharge curves, when curves are completely stabilized. We found that the electrode structure changes significantly during this capacitance measurement and already after a short pulse of 10 s and 0.3 V the structural change is noticeable. After cycling for 24 hours, a completely new structure emerges where large fiber-like structures are developed with diameters around 20-30 µm. The galvanostatic cycling procedure has created fiber-like cellulose structures around 1000 times larger than the initial size of the nano-cellulose.

     

    Structural properties of the electrode have often been related to the electronic properties in the supercapacitor. Our result shows that due to this change in the CNF structure, the electrode properties after galvanostatic cycling are indeed also of interest to study. This structural change might be critical to device performance and durability.    

  • 35.
    Dahlström, Christina
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Andres, Britta
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Forsberg, Sven
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Coating Uniformity and its Effect on Supercapacitor Capacitance2014Konferensbidrag (Övrigt vetenskapligt)
  • 36.
    Danielsson, Sandra
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Energieffektivisering för hyresgäster: Ett samarbete med Vansbrohem2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Syftet med projektet var att hjälpa stiftelsen Vansbrohem i Vansbro kommun att sänka sina hyresgästers energikonsumtion. För att göra detta har en litteraturstudie utförts för att undersöka grunderna till vad som gör att en människa handlar på ett visst sätt gällande energienga-gemang. Huvudorsakerna beror bland annat på kunskap, vardagliga rutiner, ekonomi och beteendemönster. När ett bostadsbolag vill nå ut till sina hyresgäster är det viktigt att bygga upp en god relation och att använda sig av god kommunikation. I fallet för Vansbrohem gjordes detta med hjälp av en enkät speciellt framtagen för att passa hyresgäs-terna på det utvalda bostadsområdet på Ripstigen i Vansbro. För att få hyresgästerna att bli mer engagerade finns det olika sorters energispar-kampanjer att använda. För projektet i den här rapporten valdes det att ta fram en broschyr utformad efter resultatet från enkätundersökningen. Resultatet och på så vis innehållet i broschyren behandlar energieffekti-viseringsmetoder rörande varmvatten, belysning, elektricitet, tillvarata-gande av värme, sopsortering och användande av motor- och kupévär-mare. Det är viktigt att upprätthålla den goda kommunikationen mellan hyresvärd och hyresgäst och att följa upp resultatet under och efter en energisparkampanj. I rapporten presenteras fyra olika bostadsbolag i Sverige som har lyckats med detta och på så vis engagerat sina hyres-gäster att sänka den totala energikonsumtionen. Metoderna som an-vänds är individuella mätare, en mobilapp som upplyser hyresgästerna om deras klimatpåverkan och undervisning om mer hållbara vanor för nyinflyttade.

  • 37.
    Ding, Mingyue
    et al.
    Wuhan University, China.
    Ma, Longlong
    Chinese Academy of Sciences, China.
    Zhang, Qian
    Chinese Academy of Sciences, China.
    Wang, Chenguang
    Chinese Academy of Sciences, China.
    Zhang, Wennan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Wang, Tiejun
    Chinese Academy of Sciences, China.
    Enhancement of conversion from bio-syngas to higher alcohols fuels over K-promoted Cu-Fe bimodal pore catalysts2017Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 159, s. 436-441Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel K-promoted Cu-Fe bimodal derived catalyst was designed to optimize the catalytic activity and higher alcohols selectivity in higher alcohols synthesis (HAS). The characterization results indicated that the Cu-Fe bimodal derived catalyst presented the bimodal pore structures. The adding of K promoter increased the BET surface area and promoted the dispersion of Cu and Fe species in the bimodal pores without destroying the bimodal structure, whereas the excessive adding of potassium resulted in easily the aggregation of bimetal active species. Incorporation of moderate K content enhanced the reduction of Cu and Fe species and promoted the formation of active bimetal species for HAS, while the bimodal derived catalyst with excessive K content restrained the reduction of bimetal particles, decreasing the catalytic activity for higher alcohols synthesis. In addition, the gradual increasing of K content in the Cu-Fe bimodal derived catalyst strengthened the interaction of K and bimetal active species, which was combined with the “confinement effect” of bimodal pore structures, shifting product distribution towards C2 + OH.

  • 38.
    Duan, Ran
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    On Shaping Mechanical Properties of Lignocellulosic Materials by Benign Chemical Processing2016Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 39.
    Duan, Ran
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Ibrahem, Ismail
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Acid-Catalyzed Synthesis of Foamed Materials from Renewable Sources2014Ingår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 53, nr 45, s. 17597-17603Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, lightweight biobased foamed materials were successfully synthesized by the modification of renewable polysaccharides, such as starch and microcrystalline cellulose. Low-cost and nontoxic organic acids were utilized as catalysts in the first-step esterification reaction of the synthesis. The effects of different reaction conditions on the water absorbency and weight loss of freeze-casted polysaccharide–citrate–chitosan foams are discussed. Physical properties, such as pore-size distributions and compressive stress–strain curves, of the foams were determined. The characterization results show that the amide bonds formed between the carboxylic acid groups of polysaccharide–citrate and the amino groups of chitosan are crucial to the foamed material’s performance.

  • 40.
    Duan, Ran
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Ibrahem, Ismail
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    New approaches toward producing foamed materials from renewable sources.2013Konferensbidrag (Refereegranskat)
  • 41.
    Duan, Ran
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Westerlind, Bo
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Anugwom, Ikenna
    Technical Chemistry, Department of Chemistry, Chemical-Biological Centre, Umeå University; Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Finland.
    Virtanen, Pasi
    Technical Chemistry, Department of Chemistry, Chemical-Biological Centre, Umeå University.
    Mikkola, Jyri-Pekka
    Technical Chemistry, Department of Chemistry, Chemical-Biological Centre, Umeå University; Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Finland.
    Fibre stress-strain response of high temperature chemi-thermomechanical pulp treated with switchable ionic liquids2016Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, nr 4, s. 8570-8588Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The removal of lignin from a high-temperature chemi-thermomechanical pulp (HT-CTMP) using a switchable ionic liquid prepared from an organic superbase (1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)), monoethanol amine (MEA), and SO2 was investigated. The objective was to measure the fibre properties before and after removal of the lignin to analyse the contributions from lignin in the HT-CTMP fibre to the tensile properties. It was found that the fibre displacement at break - measured in zero span, which is related to fibre strain at break - was not influenced by the lignin removal in this ionic liquid system when tested dry. There was a small increase in displacement at break and a reduction in tensile strength at zero span when tested after rewetting. At short span, the displacement at break decreased slightly when lignin was removed, while tensile strength was almost unaffected when tested dry. Under rewetted conditions, the displacement at break increased and tensile strength decreased after lignin removal. Nevertheless, no dramatic differences in the pulp properties could be observed. Under the experimental conditions, treatment with the ionic liquid reduced the lignin content from 37.4 to 15.5 wt%.

  • 42.
    Eivazihollagh, Alireza
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Metal-Chelate Complexes in Alkaline Solution: On Recovery Techniques and Cellulose-based Hybrid Material Synthesis2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    For decades, aminopolycarboxylate chelating agents have been extensively used in various industrial applications. The ability of chelating agents to form stable metal-chelate complexes is the main reason for using them to manage metal ions within water-based industrial processes. Considerable quantities of industrial effluent containing chelating agents and heavy metals are produced and often discharged into the environment. The toxicity of heavy metals and the non-biodegradability of the chelating agents, as well as their accumulation in the environment, has become cause for concern. The main purpose of this thesis was to evaluate and develop processes for recovery of chelated metal complexes from aqueous solution. In this regard, the membrane electrolysis technique was evaluated for recovery of copper and aminopolycarboxylic chelating ligands such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), and a surface-active derivative of DTPA, 2-dodecyldiethylenetriaminepentaacetic acid (C12-DTPA) from aqueous solution. By using this method, it was possible to simultaneously recover the chelating ligand for further reuse and collect the metals by electrodeposition, making the process more cost-effective and hindering the discharge of copper ions and chelating ligands as pollutants into the environment. In addition, the ion flotation technique with the chelating surfactant C12-DTPA could be employed to separate metal ions, especially from their dilute solutions, and concentrate them in a foam phase. This is because C12-DTPA has a purpose-built functionality; besides forming strong coordination complexes with metal ions, it is also surface-active and will readily adsorb at air-water interfaces. In this study, C12-DTPA was effectively used in combination with foaming agents for the removal of toxic metal ions such as Cd2+, Zn2+, and Sr2+ from aqueous solution using ion flotation. From an economical perspective, this method could be combined with the membrane electrolysis technique to recover metal and regenerate chelating surfactant so that it can be reused.

    The present work also shows the synthesis of metal and metal oxide(s) nanoparticles (NPs) in alkaline aqueous solution containing chelated metal ions, in order to fabricate metal NPs–cellulose hybrid materials. Cellulose is the most abundant renewable material, with good mechanical performance and chemical resistivity in a wide range of solvents, which makes it a promising material to support metal NPs. In this respect, we developed a rapid and inexpensive one-pot synthesis of spherical copper NPs in a cellulose matrix. The hybrid material displayed antibacterial properties for both the gram-negative and gram-positive bacteria. The synthesis was further developed by studying the influence of various chelating ligands and surfactants on the NPs’ morphology and chemical composition. According to the results, DDAO, a zwitterionic surfactant, was found to mediate the formation of pure octahedral Cu2O NPs. In addition, a hybrid material film composed of regenerated cellulose and synthesized Cu2O nano-octahedrons was fabricated by spin-coating.

  • 43.
    Eivazihollagh, Alireza
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Bäckström, Joakim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Carlsson, Fredrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Ibrahem, Ismail
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    One-pot synthesis of cellulose-templated copper nanoparticles with antibacterial properties2017Ingår i: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 187, s. 170-172Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report a facile in situ synthesis of spherical copper nanoparticles (NPs) templated by a gelled cellulose II matrix under alkaline aqueous reaction conditions. In under 20 min, the hybrid material could be obtained in a one-pot reaction. Field-emission scanning electron microscopy (FE-SEM) revealed that the polycrystalline NPs of 200–500 nm were well distributed in the regenerated cellulose matrix. The average Cu crystallite size was of the order of 20 nm, as estimated from both X-ray diffraction (XRD) and FE-SEM. XRD data also indicated that the composite contained up to approximately 20% Cu2O. In suspensions containing the hybrid material, growth of Escerichia coli and Staphylococcus aureus strains was inhibited by 80% and 95%, respectively, after 72 h. The synthesis procedure offers a general approach to designing various low-cost hybrid materials of almost any shape, and the concept could be extended to utilization areas such as catalysis, functional textiles, and food packaging as well as to electronic applications.

  • 44.
    Eivazihollagh, Alireza
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Bäckström, Joakim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Electrochemical recovery of copper complexed by DTPA and C12-DTPA from aqueous solution using a membrane cell2018Ingår i: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 93, nr 5, s. 1421-1431Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND

    The electrochemical recovery of copper from DTPA and C12-DTPA (a surface-active derivative of DTPA) complex solutions was investigated in a membrane flow cell. Electrolysis time, solution flow rate, applied current density, and solution pH were evaluated.

    RESULTS

    The chelating surfactant C12-DTPA can promote the kinetics of copper electrodeposition more than DTPA depending on the experimental conditions. At a current density of 30 A m–2, a solution flow rate of 0.6 L min–1, and pH 10 after 180 min treatment, the copper recovery and current efficiency were 50% and 43.3%, respectively, in the Cu(II)-DTPA system and about 65% and 53.6%, respectively, in the Cu(II)-C12-DTPA system. The differences in the amount of recovery could be explained in terms of differences in the diffusion of copper complexes with DTPA and C12-DTPA to the cathode, as well as their solution behavior and pH-dependent conditional stability constants (log10 K’CuDTPA3-).

    CONCLUSION

    Electrochemical methods could be effectively combined with foam flotation for the chelating surfactant C12-DTPA, to recover copper and C12-DTPA. This makes the overall treatment more sustainable, and can be helpful in complying with the increasingly stringent environmental regulations

  • 45.
    Eivazihollagh, Alireza
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Bäckström, Joakim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Influences of the operational variables on electrochemical treatment of chelated Cu(II) in alkaline solutions using a membrane cell2017Ingår i: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 92, nr 6, s. 1436-1445Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND

    The electrochemical recovery of copper and chelating agent from their complex solution using a membrane flow cell was investigated. The parameters electrolysis time, solution pH, current density, and temperature were investigated.

    RESULTS

    Electrochemical investigation indicated that chelating ligands can be recovered by the electrodeposition of copper ions on the cathode. For copper and EDTA recovery, the results indicated that recovery efficiency was affected by time, current density, and temperature. The recovery process was not influenced by pH in the range studied (pH 8–12), which can be explained by the low variation in the conditional stability constant, i.e. Δlog10 K' ≤ 0.7, over the pH range. However, when NTA, EDTA, and DTPA were compared, the results indicated that the recovery efficiency decreased as the conditional stability constant of the chelating agent–Cu(II) complex increased. The maximum current efficiency of copper and EDTA recovery after 5 h of treatment was approximately 85%, whereas the recovery was 80% of the initial concentration (0.05 mol L−1) at a current density of 1 A dm−2, temperature of 333 K, and pH of 10.

    CONCLUSION

    Relatively high recovery efficiency makes the process fairly sustainable and hinders the discharge of copper ions and chelating ligands as pollutants into the environment. 

  • 46.
    Eivazihollagh, Alireza
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Controlled Synthesis of Cu and Cu2O NPs and Incorporation of Octahedral Cu2O NPs in Cellulose II Films2018Ingår i: Nanomaterials, ISSN 2079-4991, Vol. 8, nr 4, artikel-id 238Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, Cu and Cu2O nanoparticles (NPs) were synthesized through chemical reduction of soluble copper-chelating ligand complexes using formaldehyde as a reducing agent. The influence of various chelating ligands, such as ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and a surface-active derivative of DTPA (C12-DTPA), as well as surfactants (i.e., hexadecyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium chloride (DoTAC), sodium dodecyl sulfate (SDS), and dimethyldodecylamine-N-oxide (DDAO)), on morphology and the composition of produced NPs was investigated. In the absence of surfactants, spherical copper particles with polycrystalline structure could be obtained. X-ray diffraction (XRD) analysis revealed that, in the presence of EDTA, the synthesized NPs are mainly composed of Cu with a crystallite size on the order of 35 nm, while with DTPA and C12-DTPA, Cu2O is also present in the NPs as a minority phase. The addition of ionic surfactants to the copper–EDTA complex solution before reduction resulted in smaller spherical particles, mainly composed of Cu. However, when DDAO was added, pure Cu2O nano-octahedrons were formed, as verified by high-resolution scanning electron microscopy (HR-SEM) and XRD. Furthermore, a hybrid material could be successfully prepared by mixing the octahedral Cu2O NPs with cellulose dissolved in a LiOH/urea solvent system, followed by spin-coating on silica wafers. It is expected that this simple and scalable route to prepare hybrid materials could be applied to a variety of possible applications.

  • 47.
    Eivazihollagh, Alireza
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Tejera, Javier
    Chemical Engineering Department, Complutense University of Madrid, E-28040 Madrid, Spain.
    Svanedal, Ida
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Blanco, Angeles
    Chemical Engineering Department, Complutense University of Madrid, E-28040 Madrid, Spain.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Removal of Cd2+, Zn2+, and Sr2+ by Ion Flotation, Using a Surface-Active Derivative of DTPA (C12-DTPA)2017Ingår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 56, nr 38, s. 10605-10614Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ion flotation was studied for the removal of cadmium, zinc, and strontium ions from aqueous solutions at pH 5–9 in a customized flotation cell, using an aminopolycarboxylic chelating surfactant, 2-dodecyldiethylenetriamine pentaacetic acid (C12-DTPA) in combination with two foaming agents: dodecyltrimethylammonium chloride (DoTAC) and dimethyldodecylamine-N-oxide (DDAO). The results from experiments showed that both Zn2+ and Cd2+ could be removed via ion flotation to 100% at pH 5, and Sr2+ could be removed via ion flotation to 60%–70% at pH 7–9. The removal of metal ions from the flotation cell was seen to vary with pH, but this was not exclusively related to the magnitudes of the formed metal ion-chelating surfactant conditional stability constants. The removal was also dependent on the foam properties of the samples that were found to vary over the investigated pH interval. The outcome of the investigation points to the chelating surfactant C12-DTPA having excellent chelating properties for all of the studied ions above pH 7. In combination with correctly chosen foaming agents, the optimized surfactant system could be expected to provide very efficient remediation of waters polluted with metal ions via ion flotation.

  • 48.
    Enberg, Sofia
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Norske Skog Saugbrugs.
    Storage of Hydrogen Peroxide Bleached Mechanical Pulp: Reduction in Reflectance over the Visible Spectrum2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The objective of this thesis is to determine possible causes of the darkening of hydrogen peroxide bleached mechanical pulp over the visible spectrum and their relative contributions. It focuses on both process conditions and the composition of the pulp and the dilution water, including additions or losses of material along the process line from the bleach tower to the paper machine.

    A mapping of the optical properties of the pulp along the process showed that the fine fraction of the pulp darkened more than the long fibre fraction. Simulation of retention times of different fractions showed that the main part of the fine material is retained in the paper within a few hours, a small part might circulate for considerably longer time and may therefore be strongly coloured.

    Storage trials were mainly performed using a hydrogen peroxide bleached mechanical pulp intended for SC paper made of Norway spruce (Picea abies), sampled on one occasion and stored in a freezer. Unwashed or well-washed pulp was stored in distilled water or in different process waters. Some complementary trials were included, e.g. unbleached pulp.

    Time and temperature were the process variables that gave the strongest darkening of the pulp, as expected, both in a clean and a more process-like system, whereas pH only had an effect in the presence of process waters; the highest brightness stability was seen at a pH around 5.5–6.0.

    The darkening was due to an increase in the light absorption coefficient (k) beginning at short wavelengths, but after longer storage times the increase in kλ also became noticeable at longer wavelengths. The colour (CIE L*, a*, b*) of the pulp changed towards red and yellow, initially more towards red and then more towards yellow. These changes were clearly visible.

    Washing of the bleached pulp made it less sensitive to storage; possibly due to the removal of extractives, lignin-like substances, metals and pulp fines. This washing had little effect before storage and the amount of material removed was small.

    The pulp darkened more when stored in process waters compared to distilled water. Apart from fibres, most of the colour was associated with pulp fines or filler but some colour was also found in the dissolved and colloidal fractions. At an increased pulp consistency, the increase in k460 was smaller.

    Storage in white water from the paper machine gave extensive discolouration with a shoulder in the absorption spectrum around 550–650 nm, which increased with time. The addition of ferric ions increased the light absorption coefficient during storage, but could not explain the increased absorption at 550–650 nm nor could it be the only cause of the darkening in the mill system. A cationic basic violet dye gave a shoulder in the absorption spectrum similar to that of the mill system, but the absorption of the dye did not increase during storage. Model calculations indicate, but do not prove, that ferric ions together with violet and red dyes could have played a major, but not exclusive role in the colour observed in the mill system after storage. The darkening not accounted for, at longer wavelengths and around 550–650 nm, is suggested to be related to fines and fillers including dissolved and colloidal substances associated with these particles.

    A method to produce representative sheets for determination of optical properties of mechanical pulps was developed. The new method makes it possible to follow changes in light absorption and light scattering coefficients over the visible range of wavelengths. It is approximately six times faster than standard methods, reduces the risk of additional darkening of the sample and can be used with small pulp quantities.

    The deviation from the expected linear behaviour of the light scattering coefficient, s, at wavelengths corresponding to strong light absorption has been studied using the Kubelka-Munk model and the angular resolved DORT2002 radiative transfer solution method. The decrease in s could not be explained by errors introduced in the Kubelka-Munk modelling by anisotropic scattering.

  • 49.
    Enberg, Sofia
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Opdal, Øivind
    Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Axelsson, Patrik
    Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Eriksen, Øyvind
    Paper & Fibre Res Inst, NO-7491 Trondheim, Norway.
    Rundlöf, Mats
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Capisco Sci & Art, SE-60234 Norrkoping, Sweden.
    Paulsson, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. AkzoNobel Pulp & Performance Chem, SE-44580 Bohus, Sweden.
    Mapping and modelling of optical properties from pulp to super calendered paper2015Ingår i: Appita journal, ISSN 1038-6807, Vol. 68, nr 2, s. 128-138-Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    During production of mechanical pulp based paper, the pulp darkenswithin the process which represents a significant cost for the mill. Amapping of the optical properties of the pulp was conducted along theprocess, from pulp mill to paper machine, at a mill producing supercalendered (SC) paper on three paper machines. The focus was to evaluateat which positions in the mill the discolouration occurs and also whichfraction of the pulp darkens the most.The fine fraction of the pulp darkened more than the long fibrefraction. Bleached pulp diluted with white water from the paper machinedarkened more during storage than pulp diluted with clear filtrate. Thewhite water contains a considerable amount of suspended solids, i.e.pulp fines and clay. There was a tendency for a shoulder in absorptionspectra of the pulp stored in white water from the paper machine in theregion 550 to 650 nm, both for fibres and for fines. This is in the sameregion where the added dyes have their absorption maxima and also somecomplexes between iron and some of the components among lignin and theextractives. Simulation of retention times of different fractions showedthat, although the main part of the fine material is retained in thepaper within a few hours, a small part might circulate for considerablylonger time.

  • 50.
    Enberg, Sofia
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Rundlöf, Mats
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Paulsson, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. AkzoNobel Pulp & Performance Chem, SE-85170 Bohus, Sweden.
    Axelsson, Patrik
    Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Eriksen, Oyvind
    Paper & Fibre Res Inst, NO-7491 Trondheim, Norway.
    Engstrand, Per
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Some causes of formation of colour during storage of hydrogen-peroxide bleached Norway spruce mechanical pulp2014Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, nr 2, s. 356-366Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The discolouration of hydrogen-peroxide bleached Norway spruce mechanical pulp during storage in mill systems was studied and the contributions of process water, iron and dyes were evaluated over the visible spectrum. Washing of the pulp made it less sensitive to storage, possibly due to the removal of extractives, lignin-like substances, iron and pulp fines. Storage in white water gave extensive discolouration with a shoulder in the absorption spectrum at around 550-650 nm. Most of the colour was associated with pulp fines or filler but some colour was also found in smaller fractions and in the water phase. The addition of ferric ions increased the light absorption coefficient during storage, initially at short wavelengths and then over the whole spectrum, but could not explain the increased absorption at 550-650 nm and could not be the only cause of the darkening in the mill system. A cationic basic violet dye gave a shoulder in the absorption spectrum similar to that in the mill system, but the absorption in this area did not increase during storage. Model calculations indicate that ferric ions together with violet and red dyes could explain a major part, but not all, of the colour observed in the mill system after storage. The darkening not accounted for at longer wavelengths and around 550-650 nm is suggested to be related to fines and fillers including dissolved and colloidal substances associated with these particles.

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