Change search
Refine search result
1234 1 - 50 of 191
CiteExportLink to result list
Permanent link
Cite
Citation style
  • harvard-cite-them-right
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    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.

    Download full text (pdf)
    fulltext
  • 2. 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, p. 83-89Article 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.

  • 3.
    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, p. 3137-3145Article 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.

  • 4.
    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, p. 35-43Article 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.

    Download full text (pdf)
    FULLTEXT01
  • 5.
    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)
    Download full text (pdf)
    FULLTEXT01
  • 6.
    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)
    Download full text (pdf)
    FULLTEXT01
  • 7.
    Al-Ashor, Safana
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sustainable food packaging based on polyhydroxyalkanoate2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Norwegian Food Research Institute (Nofima) and the University of Borås worked together to develop this project. The commonly used packaging materials pose a serious threat to the environment, as they are produced from nonrenewable crude oil and cannot decompose naturally. Despite some manufacturers' claims of their products being eco-friendly or sustainable, they are not entirely made from renewable resources and are not biodegradable. Nevertheless, some bio-based materials have emerged as a viable alternative that can naturally break down and safely decompose in the environment. Despite many studies, biopolymers possess limited mechanical and barrier properties, which restricts their potential for use in products. To overcome this limitation, polymer blending can be employed to enhance their final properties and make them more suitable for various applications.

    The objective of this project was to design sustainable food packaging using biopolymers. PHBV, one of the PHA’s bio-based polymers, was blended with other polymers to enhance its properties as a sustainable food packaging material. Through blending, PHAs'physical, chemical, and thermal properties can be enhanced to obtain exceptional films for food packaging purposes.

    Finally, in this work, a bio-based polymer, polyhydroxyalkanoate, was used to producea biodegradable packaging system for potential food packaging applications. The effect of the physical modification of PHBV on mechanical and barrier properties was studied by blending it with biodegradable polymers such as PLA and PBAT. Thermal properties were analyzed using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and FourierIItransform infrared spectroscopy (FTIR) while the mechanical properties were evaluated by tensile test. Barrier properties were characterized using water vapor transmission rate (WVTR).

    The mechanical performance of PHBV 50%: PBAT 50% blend has been significantly improved, leading to better tensile properties. The high crystallinity of the PHBV 50%: PBAT 50% blend than other blends have been found to enhance the barrier properties of the polymer film, according to DSC analysis. FTIR investigations have suggested no difference in absorption peaks between the blends and the neat material. Furthermore, WVTR investigations have shown that PHBV50%: PBAT50% exhibits excellent barrier properties against water vapor, making it a highly promising material.

    Download full text (pdf)
    fulltext
  • 8.
    Arab Goueini, Shahdokht
    University of Borås, Faculty of Textiles, Engineering and Business.
    Produktion av polyhydroxialkanoater (PHA) med Bacillus megaterium2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Plastic production and use of plastic are increasing every year throughout the world and this is one of the world's biggest problems. Plastic is a persistent substance, and its biodegradation process can take hundreds of years. This in turn leads to the accumulation of plastic causing harmful effects on the climate, the environment, and people. One of the alternatives that has great potential when it comes to dealing with this problem is to reduce the use of plastics and instead increase the production and use of bioplastics or biopolymers that are biodegradable.

    Bioplastics have a shorter biodegradation time than plastics and therefore bioplastics are a good alternative instead of using ordinary plastic. There are three different groups of bioplastics, namely those that are bio-based, those that are biodegradable and those that are both bio-based and biodegradable.

    One type of bioplastic that is biodegradable and bio-based is Polyhydroxyalkanoates (PHA) which are used in various industries as PHA is one of the biopolymers that shows the greatest potential to replace plastic in the future.

    Research is underway at the University of Borås with the goal of developing a new process for the production and recycling of PHAs. The process is based on the production of PHAs from volatile fatty acids produced from acidogenic fermentation. Acid fermentation is a modified process of anaerobic digestion; the latter is used nowadays to produce biogas from waste and can be the right process for recycling PHA-based waste and for producing a cheap substrate, namely volatile fatty acids for PHA's production. This project is about a part of the process, namely the production of PHAs with bacteria. The research group at the University of Borås has a bacterial strain that has not been yet investigated for the production of PHAs. Before this bacterium can be studied for the production of PHAs from volatile fatty acids the compositionoptimization of the cultivation medium for bacterial growth is needed.

    The purpose of this work is to investigate the effect of different glucose concentrations as a source of carbon and different amounts of ammonium sulphate in the growth of the bacterium Bacillus megaterium and the production of polyhydroxyalkanoates. A comparison between the defined medium under development in this project with nutrient broth, a complex medium normally used to grow bacteria, was also carried out in order to evaluate the suitability of the defined medium to support bacterial growth. During this work several different analytical techniques have been used such as pH measurement, High-Performance Liquid Chromatography (HPLC), Spectrometer (for optical density (OD) measurement), and Fourier-Transform Infrared Spectroscopy (FTIR) to evaluate bacterial growth and production of PHA as well as PHAs composition.

    The amount of ammonium sulphate affected glucose consumption rate, where concentrations of 3 g/L and 7 g/L were shown to lead to a faster glucose consumption compared to that at 5 g/L. Therefore, 3 g/L ammonium sulphate was chosen as it represents less chemical consumption while not affecting cell growth negatively. During bacterial cultivation in a medium containing 3 g/L ammonium sulphate, 10 g/L glucose, among other compounds, glucose was completely consumed after 72 hours of bacterial growth and the maximum PHA production was 13-14% based on cell dry weight. The cultivation medium developed in this project was shown to be suitable for bacterial growth since the use of nutrient broth, normally used for bacterial growth, led to slower glucose consumption.

    Initial glucose concentration (5, 10 and 20 g/L) did not affect glucose consumption rate and should be further studied to increase cell concentration and consequently the production of PHA. One of the most studied polymers in the PHA family is polyhydroxybutyrate (PHB). During this work, it was found, through the use of FTIR, that PHB was produced.

    Download full text (pdf)
    Produktion av polyhydroxialkanoater (PHA) med Bacillus megaterium
  • 9.
    Arabi, R.
    et al.
    University of Borås, School of Engineering.
    Bemanian, S.
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Rapid Biodegradation of Methyl tert-Butyl Ether (MBTE) by Pure Bacterial cultures2007In: Iranian journal of chemistry & chemical engineering, ISSN 1021-9986, Vol. 26, no 1, p. 1-7Article in journal (Refereed)
    Abstract [en]

    Two pure bacterial strains capable of rapid degrading methyl tert–butyl ether (MTBE) were isolated from an industrial wastewater treatment plant, identified and characterized. These strains are able to grow on MTBE as the sole carbon and energy sources and completely mineralize it to the biomass and carbon dioxide. The strains were identified as Bacillus cereus and Klebsiella terrigena. Both strains are able to grow in the presence of 48 g/l MTBE in water, which is almost the maximum concentration of MTBE in the water. They were able to completely degrade 10 g/l MTBE in less than a day. The specific degradation rate of MTBE at optimum conditions were 5.89 and 5.78 g(MTBE)/g(cells). h for B. cereus and K. terrigena, respectively. The biomass yield was 0.085 and 0.076 g/g, respectively. The cultivations were carried out successfully at 25, 30 and 37 °C, while they showed the best performance at 37 °C. Neither of the strains was able to grow and degrade MTBE anaerobically.

    Download full text (pdf)
    FULLTEXT01
  • 10.
    Asadollahzadeh, Mohammadtaghi
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mahboubi, Amir
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Lennartsson, Patrik R.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Application of Fungal Biomass for the Development of New Polylactic Acid-Based Biocomposites2022In: Polymers, E-ISSN 2073-4360, Vol. 14, no 9Article in journal (Refereed)
    Abstract [en]

    Fungal biomass (FB), a by-product of the fermentation processes produced in large volumes, is a promising biomaterial that can be incorporated into poly(lactic acid) (PLA) to develop enhanced biocomposites that fully comply with the biobased circular economy concept. The PLA/FB composites, with the addition of triethyl citrate (TEC) as a biobased plasticizer, were fabricated by a microcompounder at 150 °C followed by injection molding. The effects of FB (10 and 20 wt %) and TEC (5, 10, and 15 wt %) contents on the mechanical, thermal and surface properties of the biocomposites were analyzed by several techniques. The PLA/FB/TEC composites showed a rough surface in their fracture section. A progressive decrease in tensile strength and Young’s modulus was observed with increasing FB and TEC, while elongation at break and impact strength started to increase. The neat PLA and biocomposite containing 10% FB and 15% TEC exhibited the lowest (3.84%) and highest (224%) elongation at break, respectively. For all blends containing FB, the glass transition, crystallization and melting temperatures were shifted toward lower values compared to the neat PLA. The incorporation of FB to PLA thus offers the possibility to overcome one of the main drawbacks of PLA, which is brittleness.

    Download full text (pdf)
    fulltext
  • 11.
    Asadollahzadeh, Mohammadtaghi
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mohammadi, Marzieh
    University of Borås, Faculty of Textiles, Engineering and Business.
    Lennartsson, Patrik R.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Fungal biotechnology2023In: Current Developments in Biotechnology and Bioengineering: Filamentous Fungi Biorefinery / [ed] Mohammad J. Taherzadeh, Jorge A. Ferreira, Ashok Pandey, Elsevier, 2023, p. 31-66Chapter in book (Refereed)
    Abstract [en]

    Filamentous fungi are an amazing group of microorganisms able to both degrade and produce a plethora of different compounds. Many fungi have rather modest nutritional requirements, making them very interesting for biotechnological applications, with applications in both submerged and solid-state fermentation. Applications include agriculture, food, and feed, pharmaceutical, pulp and paper, textile industries, as well as a potential for waste valorization. Some of the current and potential products include: ethanol, citric acid, gluconic acid, itaconic acid, lactic acid, fumaric acid, and the fungal biomass as a food or feed, as well as more specific compounds such as enzymes.

  • 12.
    Aslanzadeh, Solmaz
    University of Borås, School of Engineering.
    Pretreatment of cellulosic waste and high rate biogas production2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The application of anaerobic digestion technology is growing worldwide, mainly because of its environmental benefits. Nevertheless, anaerobic degradation is a rather slow and sensitive process. One of the reasons is the recalcitrance nature of certain fractions of the substrate (e.g., lignocelluloses) used for microbial degradation; thus, the hydrolysis becomes the rate-limiting step. The other reason is that the degradation of organic matter is based on a highly dynamic, multi-step process of physicochemical and biochemical reactions. The reactions take place in a sequential and parallel way under symbiotic interrelation of a variety of anaerobic microorganisms, which all together make the process sensitive. The first stage of the decomposition of the organic matter is performed by fast growing (hydrolytic and acid forming) microorganisms, while in the second stage the organic acids produced are metabolized by the slow growing methanogens, which are more sensitive than the acidogens; thus, methanogenesis becomes the rate-limiting step. The first part of this work evaluates the effects of a pretreatment using an organic solvent, N-methylmorpholine-N-oxide (NMMO), on cellulose-based materials in order to overcome the challenge of biomass recalcitrance and to increase the rate of the hydrolysis. NMMO-pretreatment of straw separated from the cattle and horse manure resulted in increased methane yields, by 53% and 51%, respectively, in batch digestion tests. The same kind of pretreatment of the forest residues led to an increase by 141% in the methane production during the following batch digestion assays. The second part of this work evaluates the efficacy of a two-stage process to overcome the second challenge with methanogenesis as the rate-limiting step, by using CSTR (continuous stirred tank reactors) and UASB (up flow anaerobic sludge blanket) on a wide variety of different waste fractions in order to decrease the time needed for the digestion process. In the two-stage semi-continuous process, the NMMO-pretreatment of jeans increased the biogas yield due to a more efficient hydrolysis compared to that of the untreated jeans. The results indicated that a higher organic loading rate (OLR) and a lower retention time could be achieved if the material was easily degradable. Comparing the two-stage and the single-stage process, treating the municipal solid waste (MSW) and waste from several food processing industries (FPW), showed that the OLR could be increased from 2 gVS/l/d to 10 gVS/l /d, and at the same time the HRT could be decreased from 10 to 3 days, which is a significant improvement that could be beneficial from an industrial point of view. The conventional single stage, on the other hand, could only handle an OLR of 3 gVS/l/d and HRT of 7 days.

    Download full text (pdf)
    fulltext
    Download (pdf)
    omslag
    Download (pdf)
    spikblad
  • 13.
    Aslanzadeh, Solmaz
    et al.
    University of Borås, School of Engineering.
    Berg, Andreas
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Biogas Production from N-Methylmorpholine-N-oxide (NMMO) Pretreated Forest Residues2014In: Applied Biochemistry and Biotechnology, ISSN 0273-2289, E-ISSN 1559-0291, Vol. 172, no 6, p. 2998-3008Article in journal (Refereed)
    Abstract [en]

    Lignocellulosic biomass represents a great potential for biogas production. However, a suitable pretreatment is needed to improve their digestibility. This study investigates the effects of an organic solvent, N-Methylmorpholine-N-oxide (NMMO) at temperatures of 120 and 90 °C, NMMO concentrations of 75 and 85 % and treatment times of 3 and 15 h on the methane yield. The long-term effects of the treatment were determined by a semicontinuous experiment. The best results were obtained using 75 % NMMO at 120 °C for 15 h, resulting in 141 % increase in the methane production. These conditions led to a decrease by 9 % and an increase by 8 % in the lignin and in the carbohydrate content, respectively. During the continuous digestion experiments, a specific biogas production rate of 92 NmL/gVS/day was achieved while the corresponding rate from the untreated sample was 53 NmL/gVS/day. The operation conditions were set at 4.4 gVS/L/day organic loading rate (OLR) and hydraulic retention time (HRT) of 20 days in both cases. NMMO pretreatment has substantially improved the digestibility of forest residues. The present study shows the possibilities of this pretreatment method; however, an economic and technical assessment of its industrial use needs to be performed in the future.

  • 14.
    Aslanzadeh, Solmaz
    et al.
    University of Borås, School of Engineering.
    Rajendran, Karthik
    University of Borås, School of Engineering.
    Jeihanipour, Azam
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Waste textile processing into biogas using two-stage reactors2013Conference paper (Other academic)
  • 15.
    Aslanzadeh, Solmaz
    et al.
    University of Borås, School of Engineering.
    Rajendran, Karthik
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    A comparative study between conventional and two stage anaerobic process: Effect of organic loading rate and hydraulic retention time2013In: / [ed] Shu Li, Jegatheesan Veeriah, Keir Greg, Kier Merrin, Chang Chia-Yuan, CESE 2013 , 2013Conference paper (Refereed)
  • 16.
    Aslanzadeh, Solmaz
    et al.
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Pretreatment of straw fraction of manure for improved biogas production2011In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 6, no 4, p. 5193-5205Article in journal (Refereed)
    Abstract [en]

    Pretreatment of straw separated from cattle and horse manure using N-methylmorpholine oxide (NMMO) was investigated. The pretreatment conditions were for 5 h and 15 h at 120 °C, and the effects were evaluated by batch digestion assays. Untreated cattle and horse manure, both mixed with straw, resulted in 0.250 and 0.279 Nm3 CH4/kgVS (volatile solids), respectively. Pretreatment with NMMO improved both the methane yield and the degradation rate of these substrates, and the effects were further amplified with more pretreatment time. Pretreatment for 15 h resulted in an increase of methane yield by 53% and 51% for cattle and horse manure, respectively. The specific rate constant, k0, was increased from 0.041 to 0.072 (d-1) for the cattle and from 0.071 to 0.086 (d-1) for the horse manure. Analysis of the pretreated straw shows that the structural lignin content decreased by approximately 10% for both samples and the carbohydrate content increased by 13% for the straw separated from the cattle and by 9% for that separated from the horse manure. The crystallinity of straw samples analyzed by FTIR show a decrease with increased time of NMMO pretreatment.

    Download full text (pdf)
    fulltext
  • 17.
    Aslanzadeh, Solmaz
    et al.
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Pretreatment of straw fraction of manure for improved biogas production2011In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 6, no 4, p. 5193-5205Article in journal (Refereed)
  • 18.
    Avelin, Johanna
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ta vara på äpplen som restprodukt2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In Sweden, about 1.2 million tons of food waste is thrown away per year. Much of the waste is fruit and vegetables because of the consumers misconceptions about how a fruit and vegetable should appear in order to be edible. Food waste is bad both for the economy and the environment. Therefore, a changed attitude from the consumers is needed to reduce the waste of food. Lyckans äpple is a cider factory that generates about 2.5 tons of apple waste per year. At present there is no process for handling these. Therefore, the purpose of this thesis is to find out if it is possible to make use of the apple waste. To investigate if it is possible to get an alcoholic drink and some type of dried food product. Also to find out how much growth that can be obtained out of Neurospora intermedia and Aspergillus oryzae. A variety of different methods have been used. Fermentation to get an alcoholic drink, 70°C oven to get a dried food product and Solid State Fermentation to get the growth of the fungus Neurospora intermedia and Aspergillus oryzae. The result shows that an alcoholic beverage can be extracted from apple waste. To get a good and tasty beverage from apple waste with only water and fungus added is difficult because there are a lot of flavors from the apples that disappear when the must is done. On the other hand, a good beverage could be obtained using additives because the beverage has a good taste-potential. The drying gave good results. All results had basically the same taste but different texture. Getting a food product is possible. Being able to dry apple wastes are a good option as the process is easy, it tastes good and the apple waste contains good substances for the body. Results from Solid State Fermentation varied. In some experiments, the growth was greater and in others less.

    Download full text (pdf)
    fulltext
  • 19.
    Bahrami, Bahador
    et al.
    Department of Chemical Engineering, Isfahan University of Technology, Isfahan, 84156-83111 Iran.
    Behzad, Tayebeh
    Department of Chemical Engineering, Isfahan University of Technology, Isfahan, 84156-83111 Iran.
    Salehinik, Fatemeh
    Department of Chemical Engineering, Isfahan University of Technology, Isfahan, 84156-83111 Iran.
    Zamani, Akram
    University of Borås, Faculty of Textiles, Engineering and Business.
    Heidarian, Pejman
    School of Engineering, Deakin University, Geelong, VIC, 3216 Australia.
    Incorporation of Extracted Mucor indicus Fungus Chitin Nanofibers into Starch Biopolymer: Morphological, Physical, and Mechanical Evaluation2021In: Starch, ISSN 0038-9056, Vol. 73, no 7-8, article id 2000218Article in journal (Refereed)
    Abstract [en]

    Bio-nanocomposites based on starch are reinforced by different percentages of chitin nanofibers (ChNFs) and compatibilized by glycerol. Nanofibers are extracted from Mucor indicus fungus through different chemo-mechanical pretreatments. The mechnical, chemo-physical, and morphological properties of the nanocomposite starch films were evaluated and compared with the unfilled thermoplastic starch (TPS) film. Based on the obtained results, Young's modulus of the film at 5 wt.% ChNFs indicated 239% enhancement compared to the TPS film due to the existence of good interactions between starch and ChNFs. Moreover, the ultimate strength of the reinforced film at 5 wt.% ChNFs and the unreinforced counterpart are found to be 5.5 and 1.74 MPa, indicating 216% improvement; however, the elongation at break of the films decreases from 59.3% to 19.3% by adding 5 wt.% ChNFs. In addition, the moisture absorption of the film decreases after the incorporation of ChNFs. Based on the morphological study, ChNFs increase the roughness of the starch matrix with a homogenous morphology revealing the good dispersion of nanofibers in the TPS film. Finally, the nanocomposite film with 5 wt.% ChNFs show the best properties to employ for bio-film applications.

  • 20.
    Bakare, Fatimat O.
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ramamoorthy, Sunil Kumar
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Thermomechanical properties of bio-based composites made from a lactic acid thermoset resin and flax and flax/basalt fibre reinforcements2016In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 83, p. 176-184Article in journal (Refereed)
    Abstract [en]

    Low viscosity thermoset bio-based resin was synthesised from lactic acid, allyl alcohol and pentaerythritol. The resin was impregnated into cellulosic fibre reinforcement from flax and basalt and then compression moulded at elevated temperature to produce thermoset composites. The mechanical properties of composites were characterised by flexural, tensile and Charpy impact testing whereas the thermal properties were analysed by dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The results showed a decrease in mechanical properties with increase in fibre load after 40 wt.% for the neat flax composite due to insufficient fibre wetting and an increase in mechanical properties with increase fibre load up to 60 wt.% for the flax/basalt composite. The results of the ageing test showed that the mechanical properties of the composites deteriorate with ageing; however, the flax/basalt composite had better mechanical properties after ageing than the flax composite before ageing.

  • 21.
    Barghi, Hamidreza
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Synthesis and characterization of novel bulk hydrophilic acetaldehyde modified polyamide 462011Conference paper (Other academic)
  • 22. Barghi, Hamidreza
    et al.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Surface electroconductive modification of biopolymers2015In: Surface Modification of Biopolymers / [ed] Kumar, V., Singha, A.S., USA: John Wiley & Sons, 2015Chapter in book (Refereed)
  • 23.
    Bashir, Tariq
    University of Borås, School of Engineering.
    Conjugated Polymer-based Conductive Fibers for Smart Textile Applications2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Electrically conductive or electro-active fibers are the key components of smart and interactive textiles, which could be used in medical, sports, energy, and military applications in the near future. The functionalization of high-performance textile yarns/fibers with conjugated polymers can produce conductive fibers with better electro-mechanical properties, which is difficult with commonly used spinning techniques. In this thesis work, textile-based conductive yarns/fibers were prepared by coating viscose and polyester (PET) yarns with the conjugated polymer PEDOT. For coating purposes, an efficient technique called chemical vapor deposition (CVD) was used, which is a solventless technique and can produce PEDOT polymer layers with high conductivity values. The polymerization of EDOT monomer vapors and coating of oxidant (FeCl3 or FepTS) enriched viscose and PET yarns took place simultaneously. The PEDOT-coated viscose and polyester yarns showed relatively high conductivity values, which could be sufficient for many electronic applications. The polymerization process and the quality of PEDOT polymer strongly depends on different reaction conditions. In this research work, the impact of most of these reaction parameters on the electrical, mechanical, and thermal properties of PEDOT-coated conductive yarns was considered separately. Under specific reaction conditions, it was found that viscose fibers were successfully coated with PEDOT polymer and showed rather high electrical conductivity (≥ 15 S/cm). However, due to the acid hydrolysis of viscose fibers in FeCl3 solutions, the mechanical properties were drastically reduced. In order to improve the mechanical properties of conductive yarns, a relatively stable and chemical-resistant substrate (PET) was coated with PEDOT polymer. Comparative studies between PEDOT-coated viscose and PET conductive yarns showed that the electrical and mechanical properties were enhanced by changing the substrate material. Later on, PEDOT-coated conductive fibers were treated with silicone elastomer solution and due to the thin silicone layers, the hydrophobic properties, flexibility, and durability of coated yarns was improved. Furthermore, a novel electrical resistance-measuring setup was developed, which can be used not only for fibers but also for fabric structures. The electrical characterization of PEDOT-coated conductive yarns showed that it can be used effectively for sensitive fibers without damaging their surface morphology. Finally, the use of conductive yarns as stretch sensors was evaluated. For this purpose, small rectangular knitted patches of conductive yarns were prepared and then the change in electrical resistance values at different extension percentages (5–50%) was investigated. The constant variations in electrical resistance values at different extension and relaxation cycles for longer periods of time revealed that the conductive yarns produced have the potential to be used as stretch sensors for monitoring of vital signs in medical and sports applications.

    Download full text (pdf)
    FULLTEXT01
  • 24.
    Bashir, Tariq
    et al.
    University of Borås, School of Engineering.
    Ali, Majid
    Cho, Sung-Woo
    Persson, Nils-Krister
    University of Borås, Swedish School of Textiles.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    OCVD polymerization of PEDOT: effect of pre-treatment steps on PEDOT-coated conductive fibers and a morphological study of PEDOT distribution on textile yarns2013In: Polymers for Advanced Technologies, ISSN 1042-7147, E-ISSN 1099-1581, Vol. 24, no 2, p. 210-219Article in journal (Refereed)
    Abstract [en]

    The functionalization of textile fibers with intrinsically conductive polymers has become a prominent research area throughout the world. A number of coating techniques have already been utilized and optimized to get the uniform layers of conductive polymers on the surface of different substrates. In our previous study, we produced poly(3,4-ethylenedioxythiophene) (PEDOT)-coated conductive fibers by employing oxidative chemical vapor deposition (oCVD) technique. This paper describes the effects of pre-treatment steps, such as surface treatment of textile fibers with organic solvents, drying of oxidant-enriched fibers at variable temperatures and time, and oxidant type on the electrical, mechanical, and thermal properties of PEDOT-coated conductive fibers. Two well-known oxidants, ferric(III)chloride and ferric(III)p-toluenesulfonate (FepTS), were studied, and then their results were compared. In order to verify the PEDOT-coated layer and, to some extent, its impregnation inside the viscose yarns, a morphological study was carried out by using the attenuated total reflectance Fourier transform infrared spectroscopic imaging technique and computed tomography scanning across the obtained conductive fibers. Differential scanning calorimetric and thermogravimetric analysis were utilized to investigate the thermal properties and the contents of PEDOT in PEDOT-coated fibers. The mechanical properties of conductive fibers were evaluated by tensile strength testing of produced fibers. Effects of all of these pre-treatment steps on electrical properties were analyzed with Kiethly picoammeter. This study cannot only be exploited to improve the properties of conductive fibers but also to optimize the oCVD process for the production of conductive textile fibers by coating with different conjugated polymers.

  • 25.
    Bashir, Tariq
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    Persson, Nils-Krister
    E-Textiles: A Synergic Combination of Conjugated Polymers and Textile Fibers2012Conference paper (Refereed)
  • 26.
    Bazooyar, Faranak
    University of Borås, School of Engineering.
    Molecular-level Simulations of Cellulose Dissolution by Steam and SC-CO2 Explosion2014Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Dissolution of cellulose is an important but complicated step in biofuel production from lignocellulosic materials. Steam and supercritical carbon dioxide (SC-CO2) explosion are two effective methods for dissolution of some lignocellulosic materials. Loading and explosion are the major processes of these methods. Studies of these processes were performed using grand canonical Monte Carlo and molecular dynamics simulations at different pressure/ temperature conditions on the crystalline structure of cellulose. The COMPASS force field was used for both methods. The validity of the COMPASS force field for these calculations was confirmed by comparing the energies and structures obtained from this force field with first principles calculations. The structures that were studied are cellobiose (the repeat unit of cellulose), water–cellobiose, water-cellobiose pair and CO2-cellobiose pair systems. The first principles methods were preliminary based on B3LYP density functional theory with and without dispersion correction. A larger disruption of the cellulose crystal structure was seen during loading than that during the explosion process. This was seen by an increased separation of the cellulose chains from the centre of mass of the crystal during the initial stages of the loading, especially for chains in the outer shell of the crystalline structure. The ends of the cellulose crystal showed larger disruption than the central core; this leads to increasing susceptibility to enzymatic attack in these end regions. There was also change from the syn to the anti torsion angle conformations during steam explosion, especially for chains in the outer cellulose shell. Increasing the temperature increased the disruption of the crystalline structure during loading and explosion.

    Download full text (pdf)
    FULLTEXT01
  • 27. Bazooyar, Faranak
    et al.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Niklasson, C.
    Bolton, K.
    University of Borås, School of Engineering.
    Molecular modeling of cellulose dissolution2013In: Journal of Computational and Theoretical Nanoscience, ISSN 1546-1955, E-ISSN 1546-1963, Vol. 10, no 11, p. 2639-2648Article in journal (Refereed)
    Abstract [en]

    In this work we present computational studies that shed light on the molecular mechanism of the initial stages of cellulose dissolution in saturated steam, which is an important pretreatment step in the conversion of lignocellulose to biofuel. The COMPASS, Dreiding and Universal molecular mechanics force fields and the B3LYP density functional with 6-311G, 6-311++G(d,p) and 6-311++G(2d,2p) basis sets were used to study systems containing glucose, cellobiose and water. These molecular systems were studied since they are sufficiently small to perform the density functional theory calculations in a tractable time, while also being relevant to the dissolution of cellulose in saturated steam. Comparison of the energies and structures obtained from the three force fields with those obtained from the first principles method showed that the COMPASS force field is preferred to the other two and that this force field gives similar structures obtained from the first principles method. This supports the validity of the COMPASS force field for studying cellulose dissolution in saturated steam, and preliminary simulations were performed using grand canonical Monte Carlo and molecular dynamics simulations of cellulose dissolution in saturated steam at 100 °C and 1 bar, 160 °C and 6.2 bar, and 250 °C and 39.7 bar. The results show that the cellulose crystal dissolves in saturated steam at the higher temperatures and pressures.

  • 28.
    Bjelkenfors, Isabelle
    University of Borås, Faculty of Textiles, Engineering and Business.
    Rening av spolvatten i dynasandfilter2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The water treatment plant in Mölndal has a maximum capacity of 200 liters/second (720 m3/h). The main step in the process consists of 20 DynaSand filters, which are continuous sand filters with an area of 5 m2. Just before the DynaSand filters a dose of coagulant, PAX-XL-100 (polyaluminium chloride), is added, to create flocks that are then collected in the filter. At the water treatment plant in Mölndal they want to take care of the flushing water that runs through the DynaSand filters and wash the contaminated sand. This flushing water represents about 13% of the stream in the process. To prevent sending the flushing water down the drain, it is cleaned by adding another flocculant, Magnafloc (see attachment). The flocks created are then settled in lamella. From lamella, about 1% of the water goes down the drain and the cleaned flushing water is then returned to the raw water intake. Soon, the water capacity of the water treatment plant in Mölndal must be increased to provide water to the increasing population of the city of Mölndal. A reconstruction of the plant is planned and hopefully an alternative way of purification of the flush water through the lamella-sedimentation will be found, since the addition of Magnaflock is not preferable. In this pilot study the feasibility to clean the flush water by adding an extra cushion sand filter is tested. The idea is that dirty water will make flocks again with PAX, the same coagulant which is already added before the main filters. This pilot study will be the basis for the decision, whether or not, DynaSand filters will be used in the future for the best purification of the flushing water. To get an idea of how the flocculation of the flush water works purely chemically, the flocculation experiments were first conducted in a laboratory, and then in pilot scale. However, it turned out that there are many operation problems can occur at the pilot scale, which made the evaluation of the results difficult.

    Download full text (pdf)
    fulltext
  • 29.
    Björk, Hans
    et al.
    University of Borås, School of Engineering.
    Rasmusson, Anders
    University of Borås, School of Engineering.
    A dynamic method for LCA environmental optimisation exemplified by an analysis of an energy-system with a superheated steam-dryer integrated in a local district heat and power plant.2001In: Proceedings of the International Symposium on Green Chemistry, Delhi, India, SL 2, 2001, 2001Conference paper (Other academic)
  • 30.
    Björk, Hans
    et al.
    University of Borås, School of Engineering.
    Rasmusson, Anders
    A method for LCA environmental optimisation of a dynamic process exemplifiel by an analysis of an energy-system with a superheated steam-dryer integraded in a local district heat and power plant.2002In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 87, no 3, p. 381-394Article in journal (Refereed)
  • 31.
    Björk, Hans
    et al.
    University of Borås, School of Engineering.
    Rasmusson, Anders
    University of Borås, School of Engineering.
    LCA as a dynamic tool for environmental design-exemplified by an analysis of an energy-system with a superheated steam-dryer integraded in a local district heat and power plant2002In: Proceedings of the 12th International Drying Symposium (IDS:´02), Bejing, China, 2002Conference paper (Other academic)
  • 32. Blomberg, Pontus
    Syntetiskt pärlemor: Producerat via in situ-kristallisation2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis describes a sequence of experiments which have been performed with the intention to produce synthetic nacre. Synthetic nacre is a biomimetic material based on nacre, a material which can be found in mollusc shells. Nacre is a nanocomposite which has improved mechanical properties compared to the principal component aragonite (95% wt%). The improved properties of nacre are derived from the polymeric components in the composite which allows from redistribution of forces under load. Carbonates sequester CO2 in the geological CO2-cycle. If precursor are sourced correctly, the CaCO3 in synthetic nacre can temporarily sequester CO2.

    Crystals with the intended pseudohexagonal morphology have been synthesised. However, subsequent quantitative analysis could not support these findings in a follow-up experiment. This discrepancy might have been caused by differences in the method. Moist nanopaper was found to be mineralisable while maintaining a layered structure.

    Download full text (pdf)
    fulltext
  • 33. Boileau, Hervé
    et al.
    Björk, Hans
    University of Borås, School of Engineering.
    Comparing household waste treatment policies between two medium size cities: Borås (Sweden) and Chambéry (France).2006Conference paper (Other academic)
  • 34.
    Bolton, Kim
    et al.
    University of Borås, School of Engineering.
    Richards, Tobias
    University of Borås, School of Engineering.
    Mohsenzadeh Syouki, Abas
    University of Borås, School of Engineering.
    DFT study of the adsorption and dissociation of water on Ni(111), Ni(110) and Ni(100) surfaces2014In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 627, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Water adsorption and dissociation on catalytic metal surfaces play a key role in a variety of industrial processes, and a detailed understanding of this process and how it is effected by the surface structure will assist in developing improved catalysts. Hence, a comparative study of the adsorption and dissociation of water on Ni(111), Ni(110) and Ni(100) surfaces, which is often used as catalyst, has been performed using density functional theory. The results show that the adsorption energies and dissociation rates depend on the surface structure. The adsorption energies for H2O and OH decrease in the order Ni(110) > Ni(100) > Ni(111), and for the O and H atoms the adsorption energies decrease in the order Ni(100) > Ni(111) > Ni(110). In addition, the splitting of water to OH and H has lower activation energies over less packed Ni(110) and Ni(100) surfaces compared to the highly packed Ni(111) surface. The subsequent splitting of the OH to O and H also has the lowest activation energy on the Ni(110) surface. At 463 K, which is typical for industrial processes that include the water gas shift reaction, the H2O splitting is approximately 6000 and 10 times faster on the Ni(110) surface compared to the Ni(111) and Ni(100) surfaces, respectively, and OH splitting is 200 and 3000 times faster, respectively. The complete water dissociation reaction rate decreases in the order Ni(110) > Ni(100) > Ni(111).

  • 35. Borges, Marisa
    et al.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Towards zero waste: a comparative study on solid waste management between Curitiba in Brazil and Borås in Sweden2014Conference paper (Refereed)
  • 36. Brandberg, T.
    et al.
    Karimi, K.
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Franzén, C.J.
    Gustafsson, L.
    Continuous fermentation of wheat-supplemented lignocellulose hydrolysate with different types of cell retention2007In: Biotechnology and Bioengineering, ISSN 0006-3592, E-ISSN 1097-0290, Vol. 98, no 1, p. 80-Article in journal (Refereed)
    Abstract [en]

    Medium supplementation and process alternatives for fuel ethanol production from dilute acid lignocellulose hydrolysate were investigated. Dilute acid lignocellulose hydrolysate supplemented with enzymatically hydrolysed wheat flour could sustain continuous anaerobic cultivation of Saccharomyces cerevisiae ATCC 96581 if further supplemented with ammonium sulphate and biotin. This medium composition allowed for a hexose utilisation of 73% and an ethanol production of 36 mmol l-1 h-1 in chemostat cultivation at dilution rate 0.10 h-1. Three different methods for cell retention were compared for improved fermentation of supplemented lignocellulose hydrolysate: cell recirculation by filtration, cell recirculation by sedimentation and cell immobilisation in calcium alginate. All three cell retention methods improved the hexose conversion and increased the volumetric ethanol production rate. Recirculation of 75% of the bioreactor outlet flow by filtration improved the hexose utilisation from 76% to 94%. Sedimentation turned out to be an efficient method for cell separation; the cell concentration in the reactor was 32 times higher than in the outflow after 60 h of substrate feeding. However, chemostat and continuous cell recirculation cultures became severely inhibited when the dilution rate was increased to 0.20 h-1. In contrast, an immobilised system kept producing ethanol at a stable level also at dilution rate 0.30 h-1. Biotechnol. Bioeng. 2007; 98: 80-90. © 2007 Wiley Periodicals, Inc.

  • 37.
    Börjesson, Anders
    University of Borås, School of Engineering.
    Computational Studies of Metal Clusters and Carbon Nanotubes2008Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Carbon nanotubes constitute a promising candidate material in the realisation of nanoscaled electronics. This requires the ability for systematic production of carbon nanotubes with certain properties. This is called selective carbon nanotube growth. Two important aspects related to carbon nanotube growth are investigated in order to shed some light on this issue. First the melting behaviour of nanometer sized iron particles is investigated using molec- ular dynamics simulations. The iron nanoparticles studied are mounted on a porous Al2 O3 substrate in order to mimic the experimental situation during nanotube growth with the chemical vapour deposition method. This showed that the melting temperature of a cluster on a porous substrate may be lower than the melting temperature of a cluster on a flat sub- strate. This means that the catalyst particles used for nanotube growth may be liquid. In association with these studies the role of surface curvature to melting behaviour is explored further. The second presented study concerns the docking of nickel clusters to open single wall carbon nanotube ends. The motivation for this study was the possibility to continue growth of a carbon nanotube by docking of catalyst particles to its end. This work may also be of importance for the creation of electric junctions between carbon nanotubes and metal elec- trodes. This study showed that independent of whether the metal was gently put on the nanotube end or brutally forced to the end, it is the metal that adapts to the nanotube and not vice versa. For forced docking it was seen that carbon might dissolve in to the metal. This was not seen for the gently docked clusters. Carbon dissolution might affect the electronic properties of the metal (carbide) and nanotube-metal junction.

  • 38.
    Börjesson, Anders
    University of Borås, School of Engineering.
    In silico studies of carbon nano tubes and metal clusters2010Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Carbon nanotubes have been envisioned to become a very important material in various applications. This is due to the unique properties of carbon nanotubes which can be exploited in applications on length scales spanning from the nano world to our macroscopic world. For example, the electronic properties of carbon nanotubes makes them utterly suitable for nano electronics while the strength of them makes them suitable for reinforcements in plastics. Both of these applications do however require... mer the ability for systematic production of carbon nanotubes with certain properties. This is called selective carbon nanotube growth and today this has not been achieved with total success. In the work presented in the thesis several different computational methods have been applied in our contribution to the systematic search for selective carbon nanotube growth. Put in a context of previous knowledge about carbon nanotube growth our results provide valuable clues to which parameters that control the carbon nanotube growth. In association with the latest results we even dare to, with all modesty, speculate about a plausible control mechanism. The studies presented in the thesis addressed different stages of carbon nanotube growth, spanning from the properties affecting the initiation of the growth to the parameters affecting the termination of the growth. In some more detail this included studies of the melting temperatures of nanoscaled metal clusters. The expected size dependence of the melting temperatures was confirmed and the melting temperatures of clusters on substrates were seen to depend both on the material and shape of the surface. As this constitute the premises prior to the carbon nanotube growth it was followed by studies of the interaction between carbon nanotubes and metal clusters of different size and constitution. This was done using different computational methods and at different temperatures. It soon became apparent that the clusters adapted to the carbon nanotube and not vice versa. This held true irrespectively of the constitution of the cluster, that is for both pure metal and metal carbide. It was also seen that there exist a minimum cluster size that prevent the carbon nanotube end from closing. Closure of the carbon nanotube end is likely to lead to the termination of the growth which lead to studies of other reasons for growth termination, e.g., Ostwald ripening of the catalyst particles. This was investigated with the result that the rate of the Ostwald ripening may depend on both the chirality and diameter of the carbon nanotubes. It is suggested that this may provide some answers to the controlled growth of carbon nanotubes.

    Download full text (pdf)
    fulltext
    Download (pdf)
    spikblad
  • 39.
    Börjesson, Anders
    et al.
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    First Principles Studies of the Effect of Nickel Carbide Catalyst Composition on Carbon Nanotube Growth2010In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, no 42, p. 18045-18050Article in journal (Refereed)
    Abstract [en]

    Density functional theory calculations were used to investigate the stability of single-walled carbon nanotubes (CNTs) attached to nanoparticles. The total energies and the adhesion energies between the CNTs and the nanoparticles were calculated for systems where the nanoparticles were either pure Ni or Ni carbide. It was found that the adhesion between the CNT and a pure Ni cluster is stronger than between the same CNT and a Ni carbide cluster although the energy difference was small compared to the total adhesion energies. This adhesion strength implies that CNTs are likely to remain attached to both pure Ni and Ni carbide clusters and that either pure Ni or Ni carbide clusters may be docked onto the open CNT ends to achieve continued growth or electronic contacts between CNTs and electrode materials. The system with a CNT attached to a pure Ni cluster was found to be energetically favored compared to a system containing the same CNT attached to a Ni carbide. The difference in total energy implies that a CNT should act as a sink for C atoms dissolved in the Ni carbide cluster, which means that the dissolved C atoms will be drained from the cluster, yielding a pure metal in the zero Kelvin thermodynamic limit. It is argued that this draining procedure is likely to occur even if carbon is added to the cluster at a proper rate, for example, during CNT growth.

    Download full text (pdf)
    fulltext
    Download (pdf)
    supporting information
  • 40. Cabrera-Rodríquez, Emir
    et al.
    Curbelo-Hernández, Caridad
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Effect of sodium hydroxide pretreatment at low temperature on chemical composition and enzymatic hydrolysis of spruce2013In: Revista CENIC Ciencias Químicas, ISSN 2221-2442, Vol. 43, no 1, p. 1-9Article in journal (Refereed)
    Abstract [en]

    The availability of fermentable sugars is a limiting factor for large-scale production of biological products such as bioethanol. Therefore, processes to produce sugars are being developed from lignocellulosic materials by enzymatic hydrolysis. However, the cellulose fraction are not readily accessible for the hydrolyzing enzymes and an efficient hydrolysis requires pretreatment. Several processes have been investigated for this pretreatment. Pretreatment of lignocelluloses with NaOH is among the promissing methods. In the present work, the effect of NaOH pretreatment at low temperature on chemical composition and subsequent enzymatic hydrolysis of spruce was investigated. A native spruce specie obtained from the forest around Borås city in Sweden was used in an the experiments. This wood was analyzed for carbohydrate and lignin fractions according to NREL methods. The wood was chemically pretreated using 7 % (w/w) sodium hydroxide solution with 5 % (w/v) solid content at 0 °C for 0.5, 1, 2 and 3 h. Commercial enzymes, cellulase (Celluclast 1.5 L, Novozyme, Denmark) and β-glucosidase (Novozyme 188, Novozyme, Denmark) were used in the enzymatic hydrolysis with activities of 30 FPU and 50 IU per gram of wood, respectively. The pretreatments changed the material composition. It was a very low loss of carbohydrate, about 98 % recovery, suggesting no significant carbohydrate hydrolysis. Xylans were the most affected by the pretreatments. The largest xylan removal was almost 50 %, using sodium hydroxide solution for 3 h. The profile of released sugars were also analyzed and compared. An improvement of enzymatic hydrolysis yield was observed as a result of the applied pretreatments, near 40 % glucose yield could be achieved.

    Download full text (pdf)
    fulltext
  • 41. Cahyari, Khamdan
    et al.
    Syamsiah, Siti
    Sarto,
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Harvesting biohydrogen (BioH2) and biomethane (BioCH4) from fruit waste through sequential thermophilic fermentation2011Conference paper (Refereed)
    Abstract [en]

    A sequential two stages thermophilic fermentation of fruit waste i.e. orange, banana, apple, grape, melon to produce biofuels i.e. biohydrogen (BioH2) and biomethane (BioCH4) was investigated. In the first stage, fermentative BioH2 from each waste was successfully carried out without any methane being detected. Among the wastes, apple generated more gas with cumulative BioH2 yield (CHY) as 19.91 mmol/g VS (90% of theoretical value), while the lowest one resulted from melon (8.14 mmol/g VS or 36.8%). In the second stage, fermentative BioCH4 of residual liquid from the first stage was achieved successfully for banana, VEMF, apple, grape, melon, and orange with the cumulative BioCH4 yield (CHY) as 10.62, 14.23, 15.88, 16.26, 16.74, and 18.50 mmol CH4/g VSadded respectively. It was also showed from chemical oxygen demand (COD) measurement that COD removal efficiency achieved significantly high from 48% up to 60% for all the waste except orange which was only 16.7%. It was presumed that orange contained difficult-to-degrade materials such as limonene. In fact, fermentative BioH2 of orange in higher limonene concentration at 18 mg/l was totally inhibited. A simulation of potential generated energy (PGE) from the fruits waste being treated through this method was carried out based on the quantity of worldwide harvested fruits in 2009 (FAO UN), in consideration that 10% of the fruits were wasted. It is surprisingly understood that each of the fruits waste can deliver more than 64 MWh of electricity.

  • 42. Celik, Kamile Burcu
    et al.
    Cengiz, Elif Ceylan
    Sar, Taner
    University of Borås, Faculty of Textiles, Engineering and Business.
    Dursun, Burcu
    Ozturk, Osman
    Akbas, Meltem Yesilcimen
    Demir-Cakan, Rezan
    In-situ wrapping of tin oxide nanoparticles by bacterial cellulose derived carbon nanofibers and its application as freestanding interlayer in lithium sulfide based lithium-sulfur batteries2018In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 530, p. 137-145Article in journal (Refereed)
    Abstract [en]

    Lithium-Sulfur (Li-S) batteries are mostly known for their high energy density and cost-effectiveness. However, their intrinsic problems hinder their implementation into the marketplace. The most pronounced problems are the parasitic reactions which occur between lithium polysulfides species and lithium metal anode, the volume expansion of sulfur (80%) at the end of discharge and the safety issues which are linked with the use of lithium metal. Herein this work, two approaches are applied to prevent these effects; one approach is the use of Li2S as cathode material, instead of starting from sulfur powder, both to circumvent the volume expansion of sulfur taking place during discharge and to enable lithium-free anodes cell assembling (i.e. Si-Li2S or Sn-Li2S cell configurations). Second approach deals with the lithium anode protection by SnO2 containing freestanding pyrolyzed bacterial cellulose interlayers located between anode and cathode electrodes. Since bacterial celluloses are formed in the presence of SnO2 nanoparticles, the resulting structure enables intimate contact between carbon and SnO2 nanoparticles. By employing Li2S cathode and freestanding interlayer concurrently, 468 mAh g−1 discharge capacity is obtained at C/10 current density over 100 cycles.

  • 43. Dehnavi, Gholamali Z.
    et al.
    Lauceria, Jose L.
    Rodriguez, Dani
    Beaton, Milagros
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Martin, Carlos
    Fractionation of the main components of barley spent grains from a microbrewery2011In: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 45, no 5-6, p. 339-345Article in journal (Refereed)
    Abstract [en]

    The chemical composition of barley spent grains generated in a microbrewery and their fractionation by acid hydrolysis and delignification were investigated. The material contained high amount of carbohydrates (60%), while its lignin content was lower than that reported for other sorts of barley spent grains. Different dilute-acid hydrolysis methods were evaluated for separating the main components of the spent grains, without affecting the sugars generated by starch hydrolysis. The utilization of a two-step dilute-acid hydrolysis approach allowed to hydrolyse starch in a first step, at 100 ºC, and hemicelluloses in a second step, at 121 ºC. Acetosolv and alkaline delignification were used for solubilising the lignin fraction. A higher lignin solubilisation (95% of the lignin contained in the raw material) was achieved after alkaline delignification, whereas only 34% of the initial lignin was removed by direct acetosolv. When the acetosolv treatment was combined with acid hydrolysis, lignin solubilisation increased to 74%. Lignin was precipitated from the liquors at recovery rates from 40 to 93%, as depending on the hydrolysis/delignification method used.

  • 44.
    Dursun, Burcu
    et al.
    Department of Material Science and Engineering, Gebze Technical University, 41400, Gebze, Turkey.
    Sar, Taner
    Department of Molecular Biology and Genetics, Gebze Technical University, 41400, Gebze, Turkey.
    Ata, Ali
    Department of Material Science and Engineering, Gebze Technical University, 41400, Gebze, Turkey.
    Morcrette, Mathieu
    Laboratoire de Réactivité et Chimie des Solides, CNRS UMR 7314, Université de Picardie Jules Verne, 80039, Amiens, France.
    Akbas, Meltem Yesilcimen
    Department of Molecular Biology and Genetics, Gebze Technical University, 41400, Gebze, Turkey; Institute of Biotechnology, Gebze Technical University, 41400, Gebze, Turkey.
    Demir-Cakan, Rezan
    Department of Chemical Engineering, Gebze Technical University, 41400, Gebze, Turkey.
    Pyrolyzed bacterial cellulose-supported SnO2 nanocomposites as high-capacity anode materials for sodium-ion batteries2016In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 4, p. 2597-2607Article in journal (Refereed)
    Abstract [en]

    Room-temperature sodium-based batteries have the potential for meeting large-scale grid energy storage needs. Inspired by the advancement of the design and building of electrode materials in lithium-ion batteries, improved nano-architectured electrodes can be created for sodium-ion batteries, allowing increased electron transport kinetics and conductivities. Here, nanocomposites with 3D porous structures are reported as a high-capacity anode material for sodium-ion batteries by using an easy, low-cost and environmentally friendly synthesis of pyrolyzed bacterial celluloses (PBCs). Bacterial celluloses (BCs) produced by the Gluconacetobacterxylinus strain are pyrolyzed at 500, 750 and 1000 C, resulting 50, 130 and 110 mAh g-1 capacities over 80numbers of cycles, respectively, in the presence of the binary ethylene carbonate–propylene carbonate mixture. In order to increase the cell performances, in situated SnO2 nanoparticles with bacterial cellulose(SnO2@PBC) are produced by addition as synthesized5-nm-sized SnO2 nanoparticles into the BC growth medium together with the G. xylinus strain. Following the pyrolysis at 500 C, the SnO2@PBC composite is better able to handle the accommodation of the dramatic volume change of the incorporated SnO2nanoparticles because of the interaction of oxygen-containing moieties of bacterial cellulose nanofibrils with the SnO2 nanoparticles during cellulose production. The resulting SnO2@PBC composite presents highly stable capacity retention of around400 mAh g-1 capacities at C/10 current density over 50 numbers of cycles.

    Download full text (pdf)
    fulltext
  • 45.
    Duzyer Gebizli, Sebnem
    et al.
    Department of Textile Engineering, Faculty of Engineering, Bursa Uludag University, Bursa, Turkey.
    Guclu, Nihal
    Department of Polymer Materials, Graduate School of Natural and Applied Sciences, Bursa Uludag University, Bursa, Turkey.
    Tiritoglu, Mehmet
    Department of Textile Engineering, Faculty of Engineering, Bursa Uludag University, Bursa, Turkey.
    Tezel, Serkan
    Department of Textile Engineering, Faculty of Engineering, Bursa Uludag University, Bursa, Turkey.
    Orhan, Mehmet
    University of Borås, Faculty of Textiles, Engineering and Business.
    Reversible Thermochromic Polycaprolactone Nanofibers for Repetitive Usage2023In: Fibers And Polymers, ISSN 1229-9197, E-ISSN 1875-0052, Vol. 24, no 10, p. 3393-3403Article in journal (Refereed)
    Abstract [en]

    Color change technology offers unique and challenging opportunities. Thermo-responsive color-changing nanofibers with reversibility have great potential as thermal sensors due to their increased sensitivity and fast response. Herein, polycaprolactone (PCL) nanofibers were produced by adding a leuco-based thermochromic dye with various concentrations (1%, 3%, and 5% wt corresponding to PCL1, PCL3, and PCL5, respectively). The color-changing properties with repetitive heating and cooling were studied, and the effect of dye concentration on the nanofiber properties was determined. The surface properties, dye presence, thermal and mechanical properties were analyzed by SEM–EDS, FTIR, DSC, and tensile tests. Finally, the color change properties were monitored by 1000 heating and cooling cycles between 20 and 40 °C. Thermochromic PCL nanofibers were successfully produced by electrospinning. However, some agglomerates were observed on the nanofibers with increasing dye concentration in SEM images. It was seen that the optimum dye concentration was 3% in terms of the electrospinnability. For PCL5, both presence of carbon, oxygen, nitrogen, and fluorine in EDS spectra, the shifted peaks at 2917 and 2849 cm−1, and the new peaks at 1558, 1517, 1330, 1274, 1213 and 883 cm−1 in FTIR spectra confirmed that dye had been successfully incorporated into the PCL structure. The dye addition caused a decrease in the crystallization degrees, which resulted in lower mechanical properties. PCL5 had the lowest modulus. Color measurements showed that 1% of dyes concentration was not sufficient for the thermochromic property, and the color change was still visually detectable for PCL3 and PCL5 even after 1000 heating and cooling cycles. Color change activation temperature (TA) was confirmed between 30 and 32 °C, and the stability of color change was confirmed for 1000 heating and cooling cycles. After 1000 heating and cooling cycles, the color change was still detectable for PCL3 and PCL5. Consequently, this study showed that reversible thermochromic PCL nanofibers could be promising materials for future sensor applications.

  • 46.
    Eliasson, Anna
    University of Borås, Faculty of Textiles, Engineering and Business.
    A study of the performance of biochar as adsorbing agent in o‐DGT devices2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A new complex aspect in the matter of water quality is the occurrence of emerging organic pollutants and contaminants in waste water. The currently low extent to which treatment of waste water is performed in Brazil, and in the world as a whole, there is a considerable need for development of cheap and accurate in-situ sampling methods for far-reaching studies of surface water quality. The lack of such methods today makes the maintenance and establishing of sanitary safety difficult. This diploma work gives a brief introduction to the basic principles of the passive sampling method known as Diffusive Gradient in Thin-films (DGT). A method that could be useful for such monitoring of quality in water bodies world wide. The aim of this study is to develop a method, for the detection of organic emerging pollutants and contaminants – i.e. compounds, which usually are present at very low concentrations when found in the environment as a result of human activity. More specifically, this work investigates the potential and usefulness of the application of DGT devices in detection of organic compounds that can affect human health and ecosystems, even at low concentrations, however, their effects still are in need of further investigations. This study focuses on both purely technical as well as practical points of views. The efficiency of organic DGT (o-DGT) with biochar as the adsorbing agent is examined targeting the detection of organic pollutants and contaminants in surface water. In this sense, the specific aim of the work is to evaluate the performance of biochar as adsorbing agent. This work showed that the performance of biochar as the adsorbing agent in binding layers in o-DGT sample devices can be considered as satisfactory since all compounds of interest in this study was successfully detected, quantified an identified. Further investigations in the future are needed to determine the effects of varying pH, temperature and ion concentration in the deployment media, as well as the properties of the binding layer in relation to concentration of biochar and the thickness of the layer. These in order to optimize the method for in-situ water sampling, aiming conventional use of biochar as the adsorbing agent in the future.

    Download full text (pdf)
    fulltext
  • 47.
    Eliasson, Anna
    University of Borås, Faculty of Textiles, Engineering and Business.
    En studie av egenskaperna hos biokol som adsorberande agent i o‐DGTanordningar2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A new complex aspect in the matter of water quality is the occurrence of emerging organicpollutants and contaminants in waste water. The currently low extent to which treatment ofwaste water is performed in Brazil, and in the world as a whole, there is a considerable needfor development of cheap and accurate in‐situ sampling methods for far‐reaching studies ofsurface water quality. The lack of such methods today makes the maintenance andestablishing of sanitary safety difficult. This diploma work gives a brief introduction to thebasic principles of the passive sampling method known as Diffusive Gradient in Thin‐films(DGT). A method that could be useful for such monitoring of quality in water bodies worldwide.The aim of this study is to develop a method, for the detection of organic emerging pollutantsand contaminants – i.e. compounds, which usually are present at very low concentrationswhen found in the environment as a result of human activity. More specifically, this workinvestigates the potential and usefulness of the application of DGT devices in detection oforganic compounds that can affect human health and ecosystems, even at lowconcentrations, however, their effects still are in need of further investigations.This study focuses on both purely technical as well as practical points of views. The efficiencyof organic DGT (o‐DGT) with biochar as the adsorbing agent is examined targeting thedetection of organic pollutants and contaminants in surface water. In this sense, the specificaim of the work is to evaluate the performance of biochar as adsorbing agent. This workshowed that the performance of biochar as the adsorbing agent in binding layers in o‐DGTsample devices can be considered as satisfactory since all compounds of interest in this studywas successfully detected, quantified an identified. Further investigations in the future areneeded to determine the effects of varying pH, temperature and ion concentration in thedeployment media, as well as the properties of the binding layer in relation to concentrationof biochar and the thickness of the layer. These in order to optimize the method for in‐situwater sampling, aiming conventional use of biochar as the adsorbing agent in the future.

    Download full text (pdf)
    fulltext
  • 48. Emanuelsson, Viktor
    et al.
    Simonson, Margaret
    Gevert, Thomas
    The effect of accelerated ageing of building wires2007In: Fire and Materials, ISSN 0308-0501, E-ISSN 1099-1018, Vol. 31, no 5, p. 311-Article in journal (Refereed)
  • 49.
    Erdtman, Edvin
    et al.
    University of Borås, School of Engineering.
    Gebäck, Tobias
    University of Borås, School of Engineering.
    Ahlström, Peter
    University of Borås, School of Engineering.
    Atomistic Modelling of Protein Superabsorbents2012Conference paper (Other academic)
  • 50. Fatarella, Enrico
    et al.
    Corsi, Leopoldo
    Nesti, Solitario
    Mylläri, Ville
    Järvelä, Pentti
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Syrjala, Seppo
    Polymeric composition comprising functionalized PEEK2014Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention relates to a polymeric composition comprising functionalized polyetheretherketone (PEEK) of formula (II), in admixture with a co-polymer having a melting point lower than the melting point of the non-functionalized PEEK of formula (I). The invention further relates to the use of said composition for the preparation of fibers having antibacterial, decontaminant and self-cleaning properties, useful, for example, for making sanitary garments, such as sanitary coats and masks and for making, for example, filters for ventilation systems and filters for kitchen hoods.

1234 1 - 50 of 191
CiteExportLink to result list
Permanent link
Cite
Citation style
  • harvard-cite-them-right
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf