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  • 1.
    Abdi, Sofia
    KTH, School of Chemical Science and Engineering (CHE).
    Preparation and process optimization of encapsulating cellulose microspheres2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Microspheres are spherically shaped particles within the size range of 1-1000 μm in diameter.

    Due to the their small size and round shape, microspheres show many advantages in various

    applications such as pharmaceuticals, composites and coatings. The microspheres can be

    customized to fit a specific application and are manufactured in various forms such as solid,

    hollow and encapsulating.

    Encapsulating cellulose microspheres have been produced in this project by the emulsionsolvent

    evaporation technique. The purpose of this study was to further investigate the

    possibility of producing encapsulating microspheres with a size range of 10-50 μm that will

    have a high encapsulation. A second purpose of this study was optimizing the emulsifier

    system for the preparation of these spheres. This has been accomplished by varying several

    process parameters such as type of emulsifiers and solvents to study the effect on morphology

    and encapsulation efficiency. The analyses of the spheres were performed with optical

    microscopy, thermal gravimetric analyzer (TGA) and scanning electron microscopy (SEM).

    The emulsifier type and concentration affected the encapsulation and size distribution but had

    no direct effect on the internal and external structure, which was multi-cellular and porous,

    respectively. The highest encapsulation in relation to average size was obtained with 0.1 v/v-

    % of the emulsifier mixture Emulsifier 1 (E1)/Emulsifier 2 (E2) (70/30 %). The solvent used

    to dissolve the polymer had a direct effect on encapsulation, a combination of Solvent 2 (S2)

    and Solvent 1 (S1) proved best for the three tested cellulose derivatives with low, medium and

    high number average molecular weight. The solvent also had an effect on the internal

    structure of the microspheres, becoming more core-shell when using the S1/S2 combination.

  • 2.
    Abdullah, Rondek
    KTH, School of Chemical Science and Engineering (CHE).
    Study of the Eutrophication of Lake Vallentuna2012Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Lake Vallentuna is situated 20 km north of Stockholm, in Täby and Vallentuna municipalities. It is a shallow eutrophicated lake, with a maximum depth of 6, 0 meter and the turnover time of the lake is 1, 6 years. Lake Vallentuna has two inlets, which are Ormstaån in the North and Karbyån in the South. The outlet from Lake Vallentuna is Hagbyån in the South-West. Lake Vallentuna is, due to human activities, influenced by many contaminants, for example phosphorus and nitrogen, which contribute to the eutrophication.

    The natural state of Lake Vallentuna involves a high phosphorus concentration, since it is a lake among fields dominated by clay. The increased phosphorus levels depend on various sources, such as sewage, agriculture, and storm water.

    The aim of this project is to describe the present state of the lake and to predict the future changes. This report will also give phosphorus and calcium levels determined for Lake Vallentunna. By the examination of the chemical and physical parameters we could estimate the contribution of pollutants. To assess the lake condition, an excursion was made to collect samples and perform measurements in the field. The samples were collected from twelve different sites.

    The eight parameters measured in this study are conductivity, temperature, pH, COD, chlorinity, alkalinity, calcium and total phosphorus. The assessment of the lake was based on the guidelines from the Swedish Environmental Protection Agency ”Bedömningsgrunder för miljökvalitet”. We compared the measured values with those in the guidelines. One conclusion is that the Lake is heavily eutrophicated.

    Our measurements indicate that the incoming amount of phosphorus is bigger than the outgoing amount of phosphorus, which means that the amount of phosphorus in the lake increases at the time for the measurements. However, the main source of phosphorus in the lake water is the internal contribution from the sediments, which have been accumulated during many years. The measured values of phosphorus show that the lake is eutrophicated.

    Lake Vallentuna contains big amounts of phosphorus and metal ions (see also Adam Kazi’s diploma work on metal ions in Lake Vallentuna[19] ). The reason is that the lake is situated in a very contaminated area.

  • 3.
    Abed, Samah
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Al-Kaisee, Farah
    University of Borås, Faculty of Textiles, Engineering and Business.
    Metallutvinning med fokus på zinkfrån avfallsflygaska med hjälp avsura processvatten2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sweden produces large amount of fly ash from waste combustion annually. Combustion the

    waste generates two types of ashes, bottom ash/slag, and fly ash. Bottom ash is considered to

    be more environmentally friendly and has a wide area of application such as road

    constructions on landfills. While the fly ash has high level of heavy metals and for instance

    dioxines which are harmful for the environment. This type of ash are deposited in a landfill

    and gets classified as a hazardous waste which is expensive given that the deposit fee is high.

    The fact that fly ash contains valuable metals as zinc, methods of recovering it are being

    developed such as acid leaching. This is a promising method as the leachate used are acid

    process water making the usage of the chemicals substantially lower which makes it

    financially viable.

    Waste incinerators in Sweden produce approximately 200 000 tons of fly ash annually and the

    majority of it is transfered to Norway to get treated and put on a landfill. Some waste

    management companies, e.g. Renova, are using another method called “the Bamberg method”

    where fly ash is mixed with sludge to form a cake and put in the company’s own landfill.

    The projects goal is to leach the fly ash by using acidic process water to obtain the metallic

    substance particularly zinc making it easier and cheaper to landfill the ash and also to

    optimize this method to get the most zinc out of the ash using minimum amount of the acidic

    process water (5% HCI).

    The laboratory work took place in the University of Borås. Fly ash and the acid process water

    which were used under the laboratory work was obtained from RenovaAB.

    The results shows that leaching the fly ash with acidic process water gave different release of

    zinc but was 88% at most. The variation in the results depends on a few factors such as

    amount of acidic process water, pH, time, blending time and the ashes content.

    This project took environment and access to acidic water in consideration, which optimized

    the method of using less amount of acid process water to get the most zinc as possible.

    The results shows that leaching fly ash with acid process water is cost efficient and easy way

    to recover zinc, which satisfy the goals of the project.

  • 4. Abel, S
    et al.
    Bäbler, Matthäus
    ETH, Inst Chem & Bioengn, Dept Chem & Appl Biosci.
    Arpagaus, C
    Mazzotti, M
    Stadler, J
    Two-fraction and three-fraction continuous simulated moving bed separation of nucleosides2004In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1043, no 2, 201-210 p.Article in journal (Refereed)
    Abstract [en]

     A new experimental set-up and a new simulated moving bed (SMB) operation are presented in this work. A desktop SMB unit developed as a modification of the commercial AKTA(TM) explorer working platform has been utilized for the separation of different mixtures of nucleosides. Both two fraction and three fraction SMB separations have been carried out, the latter made possible by the adoption of a new SMB configuration and operating mode (three fraction SMB, 3F-SMB, operation). Experiments demonstrate the feasibility of the 3F-SMB operation, and confirm the trends predicted based on considerations about retention of the components to be separated along the unit. 

  • 5. Abtahi, Zhohreh
    et al.
    Millati, Ria
    Niklasson, Claes
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Ethanol production by Mucor indicus at high glucose and ethanol concentrations2010In: Minerva biotecnologica (Testo stampato), ISSN 1120-4826, E-ISSN 1827-160X, Vol. 22, no 3-4, 83-89 p.Article in journal (Refereed)
    Abstract [en]

    Mucor indicus was cultivated under aerobic and anaerobic conditions to study its tolerance against high concentration of glucose up to 350 g/L and ethanol up to 120 g/L present in the medium. The fungus could grow well even in 350 g/L glucose and produce ethanol, but it was able to assimilate the entire glucose when its concentration was less than 200 g/L. On the other hand, M. indicus produced ethanol as the main product with yield and concentration up to 0.45 g/g and 73 g/L, respectively, while glycerol, its only major byproduct, was produced up to 24 g/L. However, the fungus was not so tolerant against exogenously added ethanol, and it could not grow with more than 40 g/L added ethanol to the culture. Under aerobic conditions, M. indicus displayed different morphology, switching from long filamentous to yeast-like growth forms by increasing initial glucose concentration. This implies that yeast-like growth can be induced by growing M. indicus at high glucose concentration. Under anaerobic conditions, only one yeast-like form was observed.

  • 6. Adamus, Grazyna
    et al.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Höglund, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Kowalczuk, Marek
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    MALDI-TOF MS Reveals the Molecular Level Structures of Different Hydrophilic-Hydrophobic Polyether-esters2009In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 6, 1540-1546 p.Article in journal (Refereed)
    Abstract [en]

    Multi- and triblock copolymers based on 1,5-dioxepan-2-one/epsilon-caprolactone (DXO/CL) were investigated by MALDI-TOF MS to determine the influence of copolymer composition and architecture on the molecular structures at the individual chain level. The copolymer compositions, average block lengths, and molecular weights were determined by H-1 and C-13 NMR and by SEC, respectively. The structures of polyether-ester oligomers (linear, cyclic) as well as the chemical structures of their end groups were established on the basis of their MALDI-TOF mass spectra. The mass spectrum of PDXO homopolymer was relatively simple, however, complex mass spectra were obtained in the case of multi- and triblock copolymers and the mass spectra clearly discerned the molecular level effect of copolymer composition and copolymer type.

  • 7.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Synthesis of reactive soybean oils for use as a biobased thermoset resins in structural natural fiber composites2009In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 115, no 6, 3137-3145 p.Article in journal (Refereed)
    Abstract [en]

    Biobased thermosets resins were synthesized by functionalizing the triglycerides of epoxidized soybean oil with methacrylic acid, acetyl anhydride, and methacrylic anhydride. The obtained resins were characterized with FTIR, 1H-NMR, and 13C-NMR spectroscopy to confirm the functionalization reactions and the extent of epoxy conversion. The viscosities of the methacrylated soybean oil resins were also measured for the purpose of being used as a matrix in composite applications. The cross-linking capability was estimated by UV and thermally initiated curing experiments, and by DSC analysis regarding the degree of crosslinking. The modifications were successful because up to 97% conversion of epoxy group were achieved leaving only 2.2% of unreacted epoxy groups, which was confirmed by 1H-NMR. The 13C-NMR confirms the ratio of acetate to methacrylate methyl group to be 1 : 1. The viscosities of the methacrylated soybean oil (MSO) and methacrylic anhydride modified soybean oil (MMSO) were 0.2 and 0.48 Pas, respectively, which indicates that they can be used in resin transfer molding process.

  • 8.
    Afewerki, Samson
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Alimohammadzadeh, Rana
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Henshaw Osong, Sinke
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Tai, Cheuk-Wai
    The Arrhenius Laboratory, Stockholm University.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Eco-friendly design for scalable direct fabrication of nanocelluloseManuscript (preprint) (Other academic)
  • 9.
    Agalo, Faith
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Synthesis of Insulin-Regulated Aminopeptidase (IRAP) inhibitors2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The need for alternative cognitive enhancers has risen due to the fact that clinical trial results of the drugs currently approved for treating these disorders have not been satisfactory.

    IRAP has become a possible drug target for treating cognitive impairment brought about by Alzheimer’s disease, head trauma or cerebral ischemia, among others. This came after the revelation that Angiotensin IV enhances memory and learning. Angiotensin IV, the endogenous ligand of IRAP has been structurally modified with the aim of producing potent IRAP inhibitors. However, the peptidic nature of these inhibitors restricts their use; they are not likely to cross the blood brain barrier.

    Other strategies for generating IRAP inhibitors have been through structure-based design and receptor based virtual screening. These drug-like molecules have exhibited positive results in animal studies.

    IRAP inhibitors have been identified via a HTS of 10500 low-molecular weight compounds to give the hit based on a spirooxindole dihydroquinazolinone scaffold, with an IC50 value of 1.5 µM. In this project, some analogues to this hit compound have successfully been synthesized using a known method, whereas others have been synthesized after additional method development.

    The application of the developed method was found to be limited, because poor yield was obtained when a compound with an electron withdrawing substituent on the aniline was synthesized. As a result of this, modification of this method may be required or new methods may have to be developed to synthesize these types of analogues.

    Inhibition capability of 5 new spirooxindole dihydroquinazolinones was tested through a biochemical assay. Compound 6e emerged as the most potent inhibitor in the series, with an IC50 value of 0.2 µM. This compound will now serve as a lead compound and should be used as a starting point for future optimization in order to generate more potent IRAP inhibitors.

     

    The full text will be freely available from 2017-07-17 17:23
  • 10. Agnihotri, S.
    et al.
    Johnsen, I.A
    Böe, M.S.
    ֘yaas, Karin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Moe, S.
    Ethanol organosolv pretreatment of softwood (Picea abies) and sugarcane bagasse for biofuel and biorefinery applications2015In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 49, no 5, 881-896 p.Article in journal (Refereed)
    Abstract [en]

    Ethanol derived from biomass has the potential to be a renewable transportation fuel that can replace gasoline. This work was carried out to establish an optimized ethanol organosolv pretreatment of Norway spruce (Picea abies) for bioethanol production (63 wt% EtOH, pH 3.5 in aqueous phase, 170–240 °C, 90 min) utilizing hydrolytic enzymes in the saccharification step. To test the generality of the method, a series of ethanol organosolv pretreatments were also performed on sugarcane bagasse (50 wt% EtOH, pH 3.5 in aqueous phase, 155–210 °C, 90–120 min). The degree of delignification increased with increasing temperature during pretreatment, and the fastest increase was observed with sugarcane bagasse. The pretreatments were carried out in a batch mode. The maximum degree of delignification of 65 % was reached at 235 °C for Norway spruce, while sugarcane bagasse reached 80 % at 210 °C. Cellulose was subjected to degradation (5–10 % points) at these temperatures. Subsequent enzymatic hydrolysis (30 FPU/g cellulose, 32 pNPGU/g cellulose, 50 °C, 48 h) of ethanol organosolv-pretreated biomass achieved complete conversion for both raw materials at the highest degrees of delignification.

  • 11.
    Agthe, Michael
    et al.
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Wetterskog, Erik
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Salazar-Alvarez, German
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Bergström, Lennart Magnus
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University.
    Dynamic growth modes of ordered arrays and mesocrystals during drop-casting of iron oxide nanocubes2014In: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 16, no 8, 1443-1450 p.Article in journal (Refereed)
    Abstract [en]

    The growth modes of self-assembled mesocrystals and ordered arrays from dispersions of iron oxide nanocubes with a mean edge length of 9.6 nm during controlled solvent removal have been investigated with a combination of visible light video microscopy, atomic force microscopy and scanning electron microscopy. Mesocrystals with translational and orientational order of sizes up to 10 μm are formed spontaneously during the final, diffusion-controlled, drop-casting stage when the liquid film is very thin and the particle concentration is high. Convection-driven deposition of ordered nanocube arrays at the edge of the drying droplet is a manifestation of the so called coffee-ring effect. Dendritic growth or fingering of rapidly growing arrays of ordered nanocubes could also be observed in a transition regime as the growth front moves from the initial three-phase contact line towards the centre of the original droplet.

  • 12.
    Aguilar, Wilson
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Study of the Synthesis of ZSM-5 from Inexpensive Raw Materials2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    ZSM-5 is an aluminosilicate with high silica ratio with suitable properties for catalysis, ion exchange, adsorption and membrane applications. ZSM-5 is usually produced industrially from concentrated systems in which there is formation of an amorphous gel phase. Typical syntheses of ZSM-5 require sources of silicon and aluminium, a mineralizer and an organic molecule as so-called templating agent. The silicon and aluminum sources widely used for the synthesis are pure reagent chemicals and in particular quaternary ammonium compounds like tetrapropyl ammonium hydroxides (TPA-OH), are employed as templating agents. Unfortunately, these compounds are rather expensive. Demand for inexpensive sources of aluminosilicates for the synthesis of ZSM-5 has increased during the last two decades. Natural raw materials such as kaolin clay and diatomaceous earth (diatomite) are two potential inexpensive sources of silica and alumina. Moreover, the molecule n-butylamine (NBA) has been reported as a low-cost templating agent to replace the quaternary ammonium compounds. The aim of this work was to show for the first time that leached metakaolinite or diatomite in combination with sodium hydroxide and n-butylamine could be used as inexpensive raw materials for the synthesis of ZSM-5 without using an additional source of silica. After synthesis optimization, both sources of aluminosilicate were found to behave differently during the course of synthesis and led to slightly different products. The chemical composition of the raw materials and the products were determined using inductively coupled plasma-sector field mass spectrometry (ICP-SFMS). Crystallinity was examined by X-ray diffractometry (XRD), the morphology was studied by extreme-high-resolution scanning electron microscopy (XHR-SEM) and the specific surface area was estimated from nitrogen adsorption data by the BET method. The chemical composition of individual crystals was determined by energy dispersive spectrometry (EDS). Dealumination of the raw materials by acid leaching made it possible to reach appropriate SiO2/Al2O3 ratios and reduced the amount of impurities. The final ZSM-5 products had a SiO2/Al2O3 ratio in the range 20 – 40. The use of leached diatomite allowed reaching higher yield of ZSM-5 crystals within comparable synthesis times. However, low amounts of mordenite were formed, which was related to the high calcium content of diatomite. Another considerable advantage of diatomite over kaolin is that diatomite does not require heat treatment at high temperature to convert the kaolin to reactive metakaolin. Further characterization of the system by XHR-SEM and EDS at low voltage was carried out in order to understand the nucleation and early growth of the ZSM-5 zeolite crystals. The observations with unprecedented detail strongly suggest that nucleation and the succeeding growth occurs on the gel surface. The growth rates in the various crystallographic directions already at an early stage are such that the shape of the growing crystals resembles that of the final crystals. However, as the early growth is interface mediated, the growth rate along the gel particles is high and the gel particles will become partially embedded inside the growing crystals at an early stage. The Si and Al nutrients are probably transported along the solid/liquid interface and possibly through the liquid in the form of nanoparticles detaching from the gel. The organic template was initially contained in the liquid. However, it remains unclear at which stage the template becomes incorporated in the solid material. EDS at low voltage was also used to gain compositional information about the sodium/calcium ion exchanged products and extraneous phases when kaolin and Bolivian montmorillonite clay were used for the synthesis of zeolite A by alkali fusion. In order to evaluate the cation exchange capacity (CEC) of the synthesized zeolite, ICP-SFMS and EDS were compared. The EDS method used in this work resulted in (Na,Ca)/Al ratios in equivalent moles very close to 1.0 as expected and was therefore found more reliable than ICP-SFMS to measure cation exchange capacity for zeolite A. To summarize, the present work shows that it was possible to synthesize well-crystallized ZSM-5 zeolite from inexpensive raw materials such as leached metakaolin or leached diatomite, sodium hydroxide and n-butyl amine. Furthermore, the crystallization mechanism evidenced in this system might be more general and also apply for other concentrated systems, e.g. those using TPA as structure-directing. Finally, this work displays that EDS at low voltage can provide valuable local compositional information in the field of zeolite synthesis.

  • 13.
    Aguilar, Wilson
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Garcia, Gustavo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Comparison between leached metakaolin and leached diatomaceous earth as raw materials for the synthesis of ZSM-52014In: SpringerPlus, E-ISSN 2193-1801, Vol. 3, no 1Article in journal (Refereed)
    Abstract [en]

    Inexpensive raw materials have been used to prepare ZSM-5 zeolites with SiO2/Al2O3 molar ratios in the range 20 - 40. Kaolin or Bolivian diatomaceous earth was used as aluminosilicate raw materials and sodium hydroxide and n-butylamine were used as mineralizing agents and template. Dealumination of the raw materials by acid leaching made it possible to reach appropriate SiO2/Al2O3 ratios and to reduce the amount of iron and other impurities. After mixing the components and aging, hydrothermal treatment was carried out and the products were recovered The results clearly show for the first time that well-crystallized ZSM-5 can be directly prepared from leached metakaolin or leached diatomaceous earth using sodium hydroxide and n-butylamine as mineralizing agents and template under appropriate synthesis conditions. A longer induction time prior to crystallization was observed for reaction mixtures prepared from leached diatomaceous earth, probably due to slower digestion of the fossilized diatom skeletons as compared with that for microporous leached metakaolin. The use of leached diatomaceous earth allowed higher yield of ZSM-5 crystals within comparable synthesis times. However, low amounts of Mordenite formed, which was related to the high calcium content of diatomaceous earth. Another considerable advantage of diatomaceous earth over kaolin is that diatomaceous earth does not require heat treatment at high temperature for metakaolinization.

  • 14.
    Aguirre Castillo, José
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Optimisation of the bottom stirring praxis in a LD-LBE converter: Investigations and tests on phosphorous removal, nitrogen as stirring gas, and slopping2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The LD-process, called after the cities Linz and Donawitz, is used to convert pig iron into crude steel by blowing oxygen on top of the pig iron. A LD-LBE converter, Lance Bubbling Equilibrium, also stirs the melt trough a bottom stirring system.

    The bottom stirring in a LD-LBE converter is believed to have a positive effect alone on the phosphorous removal. Previous studies have shown that the temperature and slag composition are the main factors affecting phosphorus removal. Phosphorus binds to the slag easier at low temperature and to slag with certain levels of dissolved calcium (a process additive). Different praxes were tested and a better dephosphorisation was reached. The bottom stirrings effect on the dissolution of calcium additives is a possible explanation to the results and mechanisms presented in this study.

    The study also aimed to investigate the use of nitrogen as stirring gas instead of argon. Nitrogen is removed from the steel during the formation of carbon oxide gases. Nitrogen was used in varying amounts as stirring gas during the first half of the oxygen blow. It proved to be safe to use as long as there was a high content of carbon in the melt. However using nitrogen beyond half of the blow showed to be risky for nitrogen sensible steels; even in small amounts since there is not enough carbon left to degas the steel from nitrogen.

    Slopping happens when formed gas from the LD-process is trapped in the slag. The slag level rises and sometimes it floods the converter resulting in yield losses. The influence of the bottom stirring on slopping was studied, which resulted in the conclusion that slopping cannot be avoided by simply improving the bottom stirring.

    Although some verification studies remains to be done, if the suggestions based on the results of this thesis were employed, savings in the oxygen and stirring gas economies could be made. Not least improvements on the iron yield.

  • 15.
    Ahlawat, Paramvir
    KTH, School of Chemical Science and Engineering (CHE).
    Modellering och implementering av simultan dubbel gradient kromatografi2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Polypeptides are becoming an important component of the antibiotic therapeutics. The production demand of therapeutic polypeptides is increasing and there is a significant interest in developing more efficient production processes. In pharmaceutical industries, polypeptides are produced as a crude mixture. Reverse phase high performance liquid chromatography (RP HPLC) is used as a typical separation technique to purify the target polypeptide from other impurities. Currently organic modifier gradients are used to elute product peptides separately from impurities. In this work, we add a second, simultaneous counter-ion gradient, in the hope of increasing separation performance and call it double gradient reverse phase chromatography. A general procedure of the model-based optimization of a polypeptide crude mixture purification process was followed to evaluate the effects of the double gradients on industrial chromatographic process. The target polypeptide elution profile was modeled with a bi-Langmuir adsorption equilibrium isotherm. The isotherm parameters of the target polypeptide were estimated by the inverse method. The model parameters of the impurities were regressed from experimental data. The variations of the isotherm parameters with the modifier concentration and counter-ion concentration were taken into account of the adsorption model. After model calibration and validation by comparison with suitable experimental data, Pareto optimization of the process were carried out to analyze the differences between single gradient chromatography and double gradient chromatography. It was observed that the additional linear gradient of counter-ion concentration did not improve the separation process. Conclusively we were able to demonstrate the concept of double gradient reverse phase chromatography within limited time and possible least experimental efforts.

  • 16.
    Ahlberg Tidblad, Annika
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Surface analysis with ESCA and GD-OES of the film formed by cathodic reduction of chromate1991In: Electrochimica Acta, Vol. 36, no 10, 1605-1610 p.Article in journal (Refereed)
    Abstract [en]

    In the chlorate process, a small addition of chromate to the electrolyte results in the formation of a cathode film, which inhibits the reduction of the intermediate hypochlorite ions. To enable surface characterization of the chromium film, it was grown by cathodic reduction onto gold and platinum substrates in hydroxide and chlorate solution. Surface analyses of this film by ESCA and GD-OES indicate that it has a distinct and constant chemical composition during growth given by the formula Cr(OH)3·xH2O. The film is thin, less than 50 Å on platinum and 80 Å on gold. It exhibits poor conductivity and covers the entire cathode surface. © 1991.

  • 17.
    Ahlgren, Maria
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Remediation of diclofenac in a non-sterile bioreactor using the white rot fungus Trametes versicolor2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    From an environmental perspective, it is interesting to assess new methods for efficient removal of drugs from wastewater. The purpose of this project was to assess the possibility of using the white rot fungus Trametes versicolor  to degrade diclofenac in a lab scale bioreactor. Two methods for quantitative analysis of diclofenac were developed, using GC-MS and UHPLC-Q-TOF (C18-column). Both methods were partly validated, with regard to sensitivity, linearity, accuracy and precision, which highlighted the superiority of UHPLC-Q-TOF over GC-MS. Two HILIC columns were also assessed, but proved unsuitable for quantitative analysis of diclofenac under the used conditions. The fungal mycelia were immobilized on plastic carriers in a nutrient solution. In initial E-flask experiments, 10 mg/L diclofenac was added to an active culture and a heat-killed control of T. versicolor . Samples were analyzed, and the results from the active culture indicated a 98% removal of diclofenac after 48 hours. The lab scale bioreactor was used in a semi-continuous mode with the influent containing 10 mg/L diclofenac. Samples were collected from the effluent to monitor the concentration over 7 days. The results showed a decline in concentration to a stable level of approximately 2 mg/L. The initial experiments showed that most of the removal (85%) was due to sorption of diclofenac, but a clear difference was seen between the active and heat-killed culture. It was impossible to conclude from the bioreactor experiment if the observed removal was due to sorption or to a combination of sorption and enzymatic remediation.

  • 18.
    Ahlström, Peter
    et al.
    University of Borås, School of Engineering.
    Aim, Karel
    Dohrn, Ralf
    Elliott, J Richard
    Jackson, George
    Jaubert, Jean Noël
    Rebello de A. Macedo, Maria Eugénia
    Pokki, Juha-Pekka
    Reczey, Kati
    Victorov, Alexey
    Fele Zilnik, Ljudmila
    Economou, Ioannis
    A Survey of the Role of Thermodynamics and Transport Properties in ChE University Education in Europe and the USA2010In: Chemical Engineering Education, ISSN 0009-2479, Vol. 44, no 1, 35-43 p.Article in journal (Refereed)
    Abstract [en]

    Thermodynamics and Transport Properties (TTP) is a central subject in the majority of chemical engineering curricula worldwide and it is thus of interest to know how it is taught today in various countries if chemical engineering education is to be improved. A survey of graduate thermodynamics education in the USA was performed a few years ago by Visco et al. [1] but as far as we know no systematic study of the undergraduate thermodynamics education has been performed, at least in recent years. In the present study, a survey about TTP education in Europe and the USA is presented. Results were obtained from nearly twenty different European countries and the USA and in total answers from about 150 universities were used for this study. The study is performed under the auspices of the Working Party of Thermodynamics and Transport Properties of the European Federation of Chemical Engineering. The survey was performed using a web based surveying system for which invitations were sent out to the universities by local representatives who were responsible for one or more countries each. Of the universities that answered more than 70 % offer BSc education 65 % offer MSc education and 55 % offer PhD education. Most universities offer at least two courses of thermodynamics. The following discussion is mainly based on the first two (undergraduate) courses reported. Half of these are taught to chemical engineers exclusively whereas the rest are taught with other branches of engineering, mainly mechanical and / or process engineering. In general two sets of course lengths were observed, corresponding either to a full semester of full time studies or to quarter of a semester. Most courses are centered around lectures and exercise classes with little or no laboratory work whereas home assignments are given in the vast majority (70-80 %) of the courses. The first course is mainly centered around the first and second law of thermodynamics whereas the second course is frequently more concentrated on phase equilibria. Both of these courses are mainly comprising of classical thermodynamics whereas the molecular interpretation often is touched upon. An analysis of the differences between thermodynamics education in Europe and the USA in presently being undertaken and results from this will also be presented. An investigation of the use of thermodynamics within industry is also on-going within the Working Party and results will be reported in the near future. [1] S.K.Dube, D.P. Visco, Chem. Eng. Ed., 2005, 258-263.

  • 19.
    Ahlström, Peter
    et al.
    University of Borås, School of Engineering.
    Aim, Karel
    Dohrn, Ralf
    Elliott, J. Richard
    Jackson, George
    Jaubert, Jean-Noel
    Rebello de A. Macedo, Maria Eugénia
    Pokki, Juha-Pekka
    Reczey, Kati
    Victorov, Alexey
    Fele Zilnik, Ljudmila
    Economou, Ioannis
    A Survey of Thermodynamics and Transport Properties in Chemical Engineering Education in Europe and the USA2008In: Proceedings of the 100th Annual Meeting of the American Institute for Chemical Engineering, 2008Conference paper (Refereed)
  • 20.
    Ahlström, Peter
    et al.
    University of Borås, School of Engineering.
    Moodley, Suren
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    Ramjugernath, D.
    University of Borås, School of Engineering.
    Computer Simulations of Vapor-Liquid-Liquid Equilibria Involving Hydrocarbons and Water2008In: Proceedings of the 100th Annual Meeting of the American Institute for Chemical Engineering, 2008, CHPC National Meeting, Durban, South Africa, December 9-10, 2008, AlChe Annual Meeting, Philadelphia, November 15-21, 2008, 2008Conference paper (Other academic)
  • 21.
    Ahmad, Waqar
    et al.
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Zheng, Li-Rong
    KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Weerasekera, Roshan
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Chen, Qiang
    KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Weldezion, Awet Yemane
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Tenhunen, Hannu
    KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Power Integrity Optimization of 3D Chips Stacked Through TSVs2009In: ELECTRICAL PERFORMANCE OF ELECTRONIC PACKAGING AND SYSTEMS, NEW YORK: IEEE , 2009, 105-108 p.Conference paper (Refereed)
    Abstract [en]

    On-chip power distribution network model for simultaneous switching of 3D ICs stacked through TSVs to choose TSV pattern, maximum number of chips in a stack and location of the decoupling capacitor for early design trade-offs.

  • 22.
    Ahmadi, Mozhgan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Brage, Claes O.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Sjöström, Krister
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Engvall, Klas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Knoef, H.
    Van De Beld, B.
    Development of an on-line tar measurement method based on photo ionization technique2011In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 176, no 1, 250-252 p.Article in journal (Refereed)
    Abstract [en]

    This paper presents work in progress for development of an on-line method based on PID (Photo Ionization Detector) for quantitative measurement of tar from biomass gasification. To calibrate the method the PID signals are compared to quantitative data of individual tar compounds obtained by an established reference method. The measured response factors for the model tar compounds demonstrated very good linearity. The PID approach was tested on-line with real producer gases from an atmospheric fluidized bed gasifier operated at 800-900 °C. The results suggest that PID can be used for continuous on-line tar measurement of product gases from biomass gasification.

  • 23.
    Ahmadi, Mozhgan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Knoef, Harrie
    Van De Beld, Bert
    Liliedahl, Truls
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Engvall, Klaus
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Development of a PID based on-line tar measurement method: Proof of concept2013In: Fuel, ISSN 0016-2361, Vol. 113, 113-121 p.Article in journal (Refereed)
    Abstract [en]

    In this study, a proof of concept was conducted for an on-line tar analyzer based on photo ionization detection (PID). Tar model compounds (naphthalene, acenaphthene, acenaphthylene, fluorene, indane and indene) were used for the initial investigation of the analysis method. It was found that the analysis method has a high sensitivity and a linear behavior was observed between the PID response and the tar concentration over a wide concentration span. The on-line tar analysis method was successfully validated against the solid phase adsorption (SPA) method using a real producer gas.

  • 24.
    Akan, Rabia
    KTH, School of Chemical Science and Engineering (CHE).
    Oorganiska-organiska nanopartikelbaserade supramolekylära strukturer för biomedicinska applikationer2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The possibility to create a multifunctional nanoparticle system via supramolecular chemistry approach with ability to simultaneously target, deliver and diagnose was investigated. Superparamagnetic iron oxide nanoparticles were synthesized by co-precipitation method and surface modified with the cyclic oligosaccharide carboxymethyl-β-cyclodextrin by three different routes. The different routes involved one, two or three reaction steps in order to reach to the final oligosaccharide functionalized nanoparticles. Esterification was performed using the intrinsic hydroxyl functionality of the nanoparticle surfaces or amine functionality was introduced prior to amidization. Further, a polymeric coating was created by incorporation of folic acid functionalized Pluronic® L-35 into carboxymethyl-β-cyclodextrin. The resulting nanoparticle based supramolecular systems were characterized by TEM, TGA, FT-IR, DLS and zeta potential techniques.

     

    The colloidal stabilities of the supramolecular nanoparticle systems were investigated in phosphate buffered saline with pH 7.4 representing body conditions. It was found that a three-step functionalization of iron oxide nanoparticles with citric acid, hexamethylenediamine and finally carboxymethyl-β-cyclodextrin resulted in the most stable ferrofluids. The average size of the resulting carboxymethyl-β-cyclodextrin functionalized nanoparticles was 25 nm prior to, and 50 nm after inclusion of folic acid functionalized Pluronic. The amount of grafted carboxymethyl-β-cyclodextrin on the nanoparticles surfaces was 25 weight %. Thus, the resulting stable ferrofluid creates an efficient platform with potential of multiple uses in biomedicine. This nanoparticle based supramolecular system combines the properties of magnetic targeting and MRI contrast enhancement due to the superparamagnetic iron oxide nanoparticle core, drug delivery of hydrophobic drugs due to the polymer capsule and selective targeting towards tumour cells due to the folic acid.

  • 25.
    Akhlaghi, Shahin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Degradation of acrylonitrile butadiene rubber and fluoroelastomers in rapeseed biodiesel and hydrogenated vegetable oil2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Biodiesel and hydrotreated vegetable oil (HVO) are currently viewed by the transportation sector as the most viable alternative fuels to replace petroleum-based fuels. The use of biodiesel has, however, been limited by the deteriorative effect of biodiesel on rubber parts in automobile fuel systems. This work therefore aimed at investigating the degradation of acrylonitrile butadiene rubber (NBR) and fluoroelastomers (FKM) on exposure to biodiesel and HVO at different temperatures and oxygen concentrations in an automated ageing equipment and a high-pressure autoclave. The oxidation of biodiesel at 80 °C was promoted by an increase in the oxygen partial pressure, resulting in the formation of larger amounts of hydroperoxides and acids in the fuel. The fatty acid methyl esters of the biodiesel oxidized less at 150 °C on autoclave aging, because the termination reactions between alkyl and alkylperoxyl radicals dominated over the initiation reactions. HVO consists of saturated hydrocarbons, and remained intact during the exposure. The NBR absorbed a large amount of biodiesel due to fuel-driven internal cavitation in the rubber, and the uptake increased with increasing oxygen partial pressure due to the increase in concentration of oxidation products of the biodiesel. The absence of a tan δ peak (dynamical mechanical measurements) of the bound rubber and the appearance of carbon black particles devoid of rubber suggested that the cavitation was caused by the detachment of bound rubber from particle surfaces. A significant decrease in the strain-at-break and in the Payne-effect amplitude of NBR exposed to biodiesel was explained as being due to the damage caused by biodiesel to the rubber-carbon-black network. During the high-temperature autoclave ageing, the NBR swelled less in biodiesel, and showed a small decrease in the strain-at-break due to the cleavage of rubber chains. The degradation of NBR in the absence of carbon black was due only to biodiesel-promoted oxidative crosslinking. The zinc cations released by the dissolution of zinc oxide particles in biodiesel promoted reduction reactions in the acrylonitrile part of the NBR. Heat-treated star-shaped ZnO particles dissolved more slowly in biodiesel than the commercial ZnO nanoparticles due to the elimination of inter-particle porosity by heat treatment. The fuel sorption was hindered in HVO-exposed NBR by the steric constraints of the bulky HVO molecules. The extensibility of NBR decreased only slightly after exposure to HVO, due to the migration of plasticizer from the rubber. The bisphenol-cured FKM co- and terpolymer swelled more than the peroxide-cured GFLT-type FKM in biodiesel due to the chain cleavage caused by the attack of biodiesel on the double bonds formed during the bisphenol curing. The FKM rubbers absorbed biodiesel faster, and to a greater extent, with increasing oxygen concentration. It is suggested that the extensive biodiesel uptake and the decrease in the strain-at-break and Young’s modulus of the FKM terpolymer was due to dehydrofluorination of the rubber by the coordination complexes of biodiesel and magnesium oxide and calcium hydroxide particles. An increase in the CH2-concentration of the extracted FKM rubbers suggested that biodiesel was grafted onto the FKM at the unsaturated sites resulting from dehydrofluorination.

  • 26.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Amir Masoud, Pourrahimi
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Christian, Sjöstedt
    Martin, Bellander
    Mikael S., Hedenqvist
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ulf W., Gedde
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Degradation of fluoroelastomers in rapeseed biodiesel at different oxygen concentrations2017In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 136, 10-19 p.Article in journal (Refereed)
    Abstract [en]

    The degradation of fluoroelastomers (FKM) based on different monomers, additives and curing systems was studied after exposure to rapeseed biodiesel at 100 °C and different oxygen partial pressures. The sorption of fuel in the carbon black-filled FKM terpolymer was promoted by the fuel-driven cavitation in the rubber. The bisphenol-cured rubbers swelled more in biodiesel than the peroxide-cured FKM, presumably due to the chain cleavage caused by the attack of biodiesel on the double bonds formed during the bisphenol curing. With any of the selected types of monomer, the FKM rubbers absorbed biodiesel faster and to a greater extent with increasing oxygen partial pressure due to the increase in concentration of the oxidation products of biodiesel. Water-assisted complexation of biodiesel on magnesium oxide and calcium hydroxide particles led to dehydrofluorination of FKM, resulting in an extensive fuel uptake and a decrease in the strain-at-break and the Young's modulus of the rubbers. An increase in the CH2-concentration determined by infrared spectroscopy, and the appearance of biodiesel flakes in scanning electron micrographs of the extracted rubbers, were explained as being due to the presence of insoluble biodiesel grafted onto FKM on the unsaturated sites resulting from dehydrofluorination. The extensibility of the GFLT-type FKM was the least affected on exposure to biodiesel because this rubber contained less unsaturation and metal oxide/hydroxide particles.

  • 27.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pourrahimi, A. M.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Christian, Sjöstedt
    Martin, Bellander
    Mikael S., Hedenqvist
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ulf W., Gedde
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Effects of ageing conditions on degradation of acrylonitrile butadiene rubber filled with heat-treated ZnO star-shaped particles in rapeseed biodiesel2017In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321Article in journal (Refereed)
    Abstract [en]

    The degradation of acrylonitrile butadiene rubber (NBR) after exposure to biodiesel at different oxygen partial pressures in an automated ageing equipment at 80 °C, and in a high-pressure autoclave at 150 °C was studied. The oxidation of biodiesel was promoted by an increase in oxygen concentration, resulting in a larger uptake of fuel in the rubber due to internal cavitation, a greater decrease in the strain-at-break of NBR due to the coalescence of cavity, and a faster increase in the crosslinking density and carbonyl index due to the promotion of the oxidation of NBR. During the high-temperature autoclave ageing, less fuel was absorbed in the rubber, because the formation of hydroperoxides and acids was impeded. The extensibility of NBR aged in the autoclave decreased only slightly due to the cleavage of rubber chains by the biodiesel attack. The degradation of NBR in the absence of carbon black was explained as being due to oxidative crosslinking. The dissolution of ZnO crystals in the acidic components of biodiesel was retarded by removing the inter-particle porosity and surface defects through heat treating star-shaped ZnO particles. The rubber containing heat-treated ZnO particles swelled less in biodiesel than a NBR filled with commercial ZnO nanoparticles, and showed a smaller decrease in the strain-at-break and less oxidative crosslinking.

  • 28.
    Akhtar, Farid
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sjöberg, Erik
    Korelskiy, Danil
    Rayson, Mark
    Hedlund, Jonas
    Bergström, Lennart
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Preparation of graded silicalite-1 substrates for all-zeolite membranes with excellent CO2/H-2 separation performance2015In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 493, 206-211 p.Article in journal (Refereed)
    Abstract [en]

    Graded silicalite-1 substrates with a high gas permeability and low surface roughness have been produced by pulsed current processing of a thin coating of a submicron silicalite-1 powder onto a powder body of coarser silicalite-1 crystals. Thin zeolite films have been hydrothermally grown onto the graded silicalite-1 support and the all-zeolite membranes display an excellent CO2/H-2 separation factor of 12 at 0 degrees C and a CO2 permeance of 21.3 x 10(-7) mol m(-2) s(-1) Pa-1 for an equimolar CO2/H-2 feed at 505 kPa and 101 kPa helium sweep gas. Thermal cracking estimates based on calculated surface energies and measured thermal expansion coefficients suggest that all-zeolite membranes with a minimal thermal expansion mismatch between the graded substrate and the zeolite film should remain crack-free during thermal cycling and the critical calcination step.

  • 29.
    Akhtar, Farid
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Sjöberg, Erik
    Korelskiy, Danil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Rayson, Mark
    Department of Chemistry, The University of Surrey, Guildford.
    Hedlund, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Bergström, Lennart
    Department of Materials and Environmental Chemistry, Stockholm University.
    Preparation of graded silicalite-1 substrates for all-zeolite membranes with excellent CO2/H2 separation performance2015In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 493, 206–211- p.Article in journal (Refereed)
    Abstract [en]

    raded silicalite-1 substrates with a high gas permeability and low surface roughness have been produced by pulsed current processing of a thin coating of a submicron silicalite-1 powder onto a powder body of coarser silicalite-1 crystals. Thin zeolite films have been hydrothermally grown onto the graded silicalite-1 support and the all-zeolite membranes display an excellent CO2/H2 separation factor of 12 at 0 °C and a CO2 permeance of 21.3×10-7 mol m-2 s-1 Pa-1 for an equimolar CO2/H2 feed at 505 kPa and 101 kPa helium sweep gas. Thermal cracking estimates based on calculated surface energies and measured thermal expansion coefficients suggest that all-zeolite membranes with a minimal thermal expansion mismatch between the graded substrate and the zeolite film should remain crack-free during thermal cycling and the critical calcination step.

  • 30.
    Alberdi-Muniain, Ane
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Gil-Negrete, N.
    Department of Applied Mechanics, CEIT and Tecnun (University of Navarra).
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Influence of carbon black and plasticisers on dynamic properties of isotropic magnetosensitive natural rubber2012In: Plastics, rubber and composites, ISSN 1465-8011, Vol. 41, no 7, 310-317 p.Article in journal (Refereed)
    Abstract [en]

    The dynamic shear modulus of magnetosensitive (MS) natural rubber composites is experimentallystudied, where influences of carbon black, plasticiser and iron particle concentrations areinvestigated at various dynamic shear strain amplitudes and external magnetic fields within thelower structure borne frequency range. The iron particles embedded in natural rubber areirregularly shaped and randomly distributed; the plasticisers simplify the iron particle blendingprocess, while carbon black reduces the production costs and improves the mechanicalproperties. The results show that the relative MS effect on the shear modulus magnitude increaseswith increased plasticiser and iron particle concentration and decreases with increased carbonblack concentration. Furthermore, their relative contributions are quantified. Consequently, thestudy provides a basis for optimising the composition of MS natural rubber to meet a variety ofrequirements, including those of vibration isolation, a promising application area for MS materials.

  • 31.
    Albero Caro, Jesus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Woldehaimanot, Mussie
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke Christoffer
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Semibatch reaction crystallization of salicylic acid2014In: Chemical engineering research & design, ISSN 0263-8762, E-ISSN 1744-3563, Vol. 92, no 3, 522-533 p.Article in journal (Refereed)
    Abstract [en]

    Reaction crystallization of salicylic acid has been investigated by experiments and modeling. In the experimental work, dilute hydrochloric acid has been added to an agitated aqueous solution of sodium salicylate in 1 L scale, and product crystals have been characterized by image analysis. The results show that the product crystal number mean size at first increases with increasing agitation rate but then gradually decreases again at further increase in stirring rate. At lower stirring rate, larger crystals are obtained when the feeding point is located close to the agitator instead of being located out in the bulk solution. The mean crystal size increases with decreasing feeding rate and with decreasing reactant concentrations. There is a decrease in mean size with increasing feed pipe diameter. These trends in the experimental results show great similarity with previous results on benzoic acid. The experimental results have been examined by a population balance model accounting for meso and micro mixing, and crystal nucleation and growth rate dispersion. It is found that the crystallization kinetic parameter estimation is quite complex, and the objective function hyper surface contains many different minima. Hence, parameter estimation has to rely on a combination of mathematical optimization strategies and a scientific understanding of the physical meaning of the parameters and their relation to current theories. As opposed to our previous work on benzoic acid, it has not been possible to find a set of kinetic parameters that provides for a good description of all experimental data.

  • 32.
    Albertsson, A-C.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Andersson, S-O.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    The mechanism of biodegradation of polyethylene1987In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 18, 73-87 p.Article in journal (Refereed)
  • 33. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Degradation of enhanced environmentally degradable polyethylene in biological aqueous media: mechanisms during the first stages1994In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 51, no 6, 1097-1105 p.Article in journal (Refereed)
  • 34. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Susceptibility of enhanced environmentally degradable polyethylene to thermal and photo-oxidation1992In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 37, no 2, 163-171 p.Article in journal (Refereed)
  • 35. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Increased biodegradation of a low-density polyethylene (LDPE) matrix in starch-filled LDPE materials1993In: Journal of environmental polymer degradation, ISSN 1064-7546, Vol. 1, no 4, 241-245 p.Article in journal (Refereed)
  • 36. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Solid-phase extraction and gas chromatographic-mass spectrometric identification of degradation products from enhanced environmentally degradable polyethylene1995In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 690, no 2, 207-217 p.Article in journal (Refereed)
  • 37. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Lindberg, T.
    Degradation product pattern and morphology changes as means to differentiate abiotically and biotically aged degradable polyethylene1995In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 36, no 16, 3075-83 p.Article in journal (Refereed)
  • 38. Albertsson, A-C.
    et al.
    Griffin, G. J. L.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Nishimoto, K.
    Watanabe, Y.
    Spectroscopic and mechanical changes in irradiated starch-filled LDPE1994In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 45, no 2, 173-178 p.Article in journal (Refereed)
  • 39. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    New tools for analyzing degradation1995In: Macromolecular Symposia, ISSN 1022-1360, E-ISSN 1521-3900, Vol. 98, no 35th IUPAC International Symposium on Macromolecules, 1995, 797-801 p.Article in journal (Refereed)
  • 40. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Abiotic degradation products from enhanced environmentally degradable polyethylene1994In: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 45, no 2, 97-103 p.Article in journal (Refereed)
  • 41. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    The Influence of Biotic and Abiotic Environments on the Degradation of Polyethylene.1990In: Progress in polymer science, ISSN 0079-6700, E-ISSN 1873-1619, Vol. 15, no 2, 177-192 p.Article in journal (Refereed)
  • 42. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Aspects of biodeterioration of inert and degradable polymers1993In: International Biodeterioration & Biodegradation, ISSN 0964-8305, Vol. 31, no 3, 161-170 p.Article in journal (Refereed)
  • 43. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Environment-adaptable polymers1993In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 41, no 3, 345-349 p.Article in journal (Refereed)
  • 44. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Biodegradable polymers1992In: Comprehensive Polymer Science, Supplement Series, Midland, Michigan: Pergamon Press, 1992, 285- p.Chapter in book (Refereed)
  • 45. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Increased biodegradation of LDPE-matrix in starch-filled LDPE materials1992In: Materials Science and Engineering, Vol. 67, 296-297 p.Article in journal (Refereed)
  • 46. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Biodegradation and testmethods for environmental and biomedical applications of polymers1990In: Degradable Materials, Boca Raton: CRC Press, 1990, 263- p.Chapter in book (Refereed)
  • 47. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Degradable Polymers1996In: The Polymeric Materials Encyclopedia: Synthesis, Properties and Applications / [ed] J. C. Salamone, Boca Raton, USA: CRC Press, 1996, 150- p.Chapter in book (Refereed)
  • 48. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Chemistry and biochemistry of polymer biodegradation1994In: Chemistry and Technology of Biodegradable Polymers / [ed] G.J.L. Griffin, London, England: Blackie Academic & Professional , 1994, 7-17 p.Chapter in book (Refereed)
  • 49. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Chromatographic fingerprinting as a means to predict degradation mechanisms1996In: Journal of environmental polymer degradation, ISSN 1064-7546, Vol. 4, no 1, 51-3 p.Article in journal (Refereed)
  • 50. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Degradable polymers for the future1995In: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 46, no 2, 114-123 p.Article in journal (Refereed)
1234567 1 - 50 of 3759
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