| 1. |
- Yu, Xiaowen, et al.
(author)
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Hydrogen Evolution Linked to Selective Oxidation of Glycerol over CoMoO4—A Theoretically Predicted Catalyst
- 2022
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In: Advanced Energy Materials. - : Wiley. - 1614-6832 .- 1614-6840. ; 12:14
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Journal article (peer-reviewed)abstract
- Electrochemical valorization of biomass waste (e.g., glycerol) for production of value-added products (such as formic acid) in parallel with hydrogen production holds great potential for developing renewable and clean energy sources. Here, a synergistic effort between theoretical calculations at the atomic level and experiments to predict and validate a promising oxide catalyst for the glycerol oxidation reaction (GOR) are reported, providing a good example of designing novel, cost-effective, and highly efficient electrocatalysts for producing value-added products at the anode and high-purity hydrogen at the cathode. The predicted CoMoO4 catalyst is experimentally validated as a suitable catalyst for GOR and found to perform best among the investigated metal (Mn, Co, Ni) molybdate counterparts. The potential required to reach 10 mA cm−2 is 1.105 V at 60 °C in an electrolyte of 1.0 ᴍ KOH with 0.1 ᴍ glycerol, which is 314 mV lower than for oxygen evolution. The GOR reaction pathway and mechanism based on this CoMoO4 catalyst are revealed by high-performance liquid chromatography and in situ Raman analysis. The coupled quantitative analysis indicates that the CoMoO4 catalyst is highly active toward C—C cleavage, thus presenting a high selectivity (92%) and Faradaic efficiency (90%) for formate production.
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| 2. |
- Farzaneh, Amirfarrokh, et al.
(author)
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Adsorption of Butanol and Water Vapors in Silicalite‑1 Films with a Low Defect Density
- 2016
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In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 32, s. 11789-11798
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Journal article (peer-reviewed)abstract
- Pure silica zeolites are potentially hydrophobic and have therefore been considered to be interesting candidates for separating alcohols, e.g., 1-butanol, from water. Zeolites are traditionally synthesized at high pH, leading to the formation of intracrystalline defects in the form of silanol defects in the framework. These silanol groups introduce polar adsorption sites into the framework, potentially reducing the adsorption selectivity toward alcohols in alcohol/water mixtures. In contrast, zeolites prepared at neutral pH using the fluoride route contain significantly fewer defects. Such crystals should show a much higher butanol/water selectivity than crystals prepared in traditional hydroxide (OH−) media. Moreover, silanol groups are present at the external surface of the zeolite crystals; therefore, minimizing the external surface of the studied adsorbent is important. In this work, we determine adsorption isotherms of 1-butanol and water in silicalite-1 films prepared in a fluoride (F−) medium using in situ attenuated total reflectance−Fourier transform infrared (ATR−FTIR) spectroscopy. This film was composed of well intergrown, plate-shaped b-oriented crystals, resulting in a low external area. Single-component adsorption isotherms of 1-butanol and water were determined in the temperature range of 35− 80 °C. The 1-butanol isotherms were typical for an adsorbate showing a high affinity for a microporous material and a large increase in the amount adsorbed at low partial pressures of 1-butanol. The Langmuir−Freundlich model was successfully fitted to the 1-butanol isotherms, and the heat of adsorption was determined. Water showed a very low affinity for the adsorbent, and the amounts adsorbed were very similar to previous reports for large silicalite-1 crystals prepared in a fluoride medium. The sample also adsorbed much less water than did a reference silicalite-1(OH−) film containing a high density of internal defects.The results show that silicalite-1 films prepared in a F− medium with a low density of defects and external area are very promising for the selective recovery of 1-butanol from aqueous solutions.
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| 3. |
- Benavente, Veronica, et al.
(author)
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Influence of lipid extraction and processing conditions on hydrothermal conversion of microalgae feedstocks – Effect on hydrochar composition, secondary char formation and phytotoxicity
- 2022
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In: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 428
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Journal article (peer-reviewed)abstract
- This study investigated the effect of lipid extraction of microalgae feedstocks subjected to hydrothermal carbonization (HTC) with regard to the carbonization degree, chemical composition and phytotoxicity of hydrochars produced under different reaction temperatures and residence times. Special attention was given to the formation and composition of secondary char, as this part of the hydrochar may be of particular importance for environmental and technical applications. A microalgae polyculture grown in municipal wastewater was extracted to retrieve lipids, and both unextracted (MA) and extracted microalgae (EMA) were used to produce hydrochars at 180–240 °C for 1–4 h. The composition of the hydrochars was thoroughly characterized by elemental analysis, thermogravimetric analysis and pyrolysis–gas chromatography/mass spectrometry analysis. MA exhibited a greater carbonization degree than EMA and contained higher amounts of secondary char under the same processing conditions. During the carbonization of EMA, more decomposition products remained in the liquid phase and less polymerization occurred than for MA, which explained the lower solid yield of EMA-derived hydrochars in comparison to MA hydrochars. Consequently, although they contained potentially toxic substances (i.e., carboxylic acids, aldehydes and ketones), the EMA-derived hydrochars exhibited a lower phytotoxic potential. This indicates that low-temperature hydrochars containing less than 10% of extractives might be suitable as soil amendments, whereas extractive-rich hydrochars would be more appropriate for other long-term applications, such as adsorbents for contaminant removal, energy storage and composite materials. Detailed characterization of microalgae-derived hydrochars is required to enable the most suitable application areas to be identified for these materials, and thereby make full use of their function as carbon sinks.
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| 4. |
- Gonska, Nathalie, et al.
(author)
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Structure-Function Relationship of Artificial Spider Silk Fibers Produced by Straining Flow Spinning
- 2020
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In: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 21:6, s. 2116-2124
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Journal article (peer-reviewed)abstract
- The production of large quantities of artificial spider silk fibers that match the mechanical properties of the native material has turned out to be challenging. Recent advancements in the field make biomimetic spinning approaches an attractive way forward since they allow the spider silk proteins to assemble into the secondary, tertiary, and quaternary structures that are characteristic of the native silk fiber. Straining flow spinning (SFS) is a newly developed and versatile method that allows production under a wide range of processing conditions. Here, we use a recombinant spider silk protein that shows unprecedented water solubility and that is capable of native-like assembly, and we spin it into fibers by the SFS technique. We show that fibers may be spun using different hydrodynamical and chemical conditions and conclude that these spinning conditions affect fiber mechanics. In particular, it was found that the addition of acetonitrile and polyethylene glycol to the collection bath results in fibers with increased beta-sheet content and improved mechanical properties.
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| 5. |
- Wahlström, Niklas, 1990-, et al.
(author)
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Cellulose from the green macroalgae Ulva lactuca: isolation, characterization, optotracing, and production of cellulose nanofibrils
- 2020
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In: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X.
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Journal article (peer-reviewed)abstract
- We report (1) successful extraction and characterization of cellulose from northern hemisphere green macroalgae Ulva lactuca (Ulva fenestrata) collected along the Swedish west coast and cultivated indoors under controlled conditions, followed by (2) its utilization in the production of lignin-free cellulose nanofibrils (CNF). Cellulose was extracted by sequential treatment with ethanol, hydrogen peroxide, sodium hydroxide, and hydrochloric acid, yielding a cellulose-rich insoluble fraction. The extracted cellulose was disintegrated into CNF using a mechanical homogenization process without any further enzymatic pre-treatments. In addition, regenerated cellulose was prepared. XRD characterization of the CNF showed characteristic peaks for the cellulose I allomorph and confirmed that the nanofibrils were semicrystalline with a crystallinity index of 48%. Regenerated cellulose was mostly amorphous with an XRD pattern indicating the presence of the cellulose II allomorph. The cellulose fractions were essentially free from inorganic substances and thermally stable up to around 260 degrees C. Structural mapping with CP-MAS C-13-NMR sustains the cellulose content of CNF and regenerated cellulose, respectively, yet ion chromatography identified the presence of 10-15% xylose in the fractions. Optotracing was used as a novel and non-disruptive tool to selectively assess the polysaccharide composition of the cellulose fractions and produced CNF aiming to shed light on this hitherto non-resolved origin of xylose in Ulva cell wall matter. Fluorescence excitation and emission spectra of a panel of 4 oligothiophenes identified and verified the presence of cellulose and sustain the conclusion that the isolated fractions consist of cellulose intertwined with a small amount of a xylose-containing glucan copolymer. [GRAPHICS] .
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| 6. |
- Akhtar, Farid, et al.
(author)
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Preparation of graded silicalite-1 substrates for all-zeolite membranes with excellent CO2/H-2 separation performance
- 2015
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In: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 493, s. 206-211
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Journal article (peer-reviewed)abstract
- 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.
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| 7. |
- Granlund, Moa Z., et al.
(author)
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Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel : Aging and characterization
- 2015
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In: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 172, s. 145-153
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Journal article (peer-reviewed)abstract
- In this study, three bimetallic catalysts are evaluated for autothermal reforming (AIR) of fuels (1 wt.% Rh and 6 wt.% X (X= Co, La or Mn) supported on high-surface area CeO2-ZrO2). The catalysts are aged for approximately 35 h and carefully characterized both as fresh and aged materials. The objective is to illuminate the changes in material properties after time on stream as well as the differences among the materials. The changes in material properties are evaluated by H-2-TPR, BET surface area analysis, TEM, SEM, and STEM. The material's tendency to coke is investigated by TPO analysis. The three materials exhibit promising initial activity. However, the Co-promoted sample decreases sharply in activity after 25 h of operation. Meanwhile, the other two materials display a more stable activity throughout the evaluated time. The deactivation of the Co-promoted material could be linked to the high amount of coke deposited during operation. Based on the results from the activity evaluation and characterization, the material promoted with lanthanum displays the most promising results. The addition of lanthanum resulted in a catalyst that was both stable and had high activity, even though a low rhodium loading is used. The material also shows superior thermal resistance compared to the other two materials. In addition, the tendency to coke is significantly lower compered to the other materials, which is especially beneficial when dealing with AIR of complex fuels.
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| 8. |
- Karim, Zoheb, et al.
(author)
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Nanocellulose based functional membranes for water cleaning : Tailoring of mechanical properties, porosity and metal ion capture
- 2016
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In: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 514, s. 418-428
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Journal article (peer-reviewed)abstract
- Multi-layered nanocellulose membranes were prepared using vacuum-filtration of cellulose nanofibers suspensions followed by dip coating with cellulose nanocrystals having sulphate or carboxyl surface groups. It was possible to tailor the specific surface area, pore structure, water flux and wet strength of the membranes via control of drying conditions and acetone treatment. Cellulose nanofibers coated with cellulose nanocrystal with carboxyl surface groups showed the highest tensile strength (95 MPa), which decreased in wet conditions (approximate to 3.7 MPa) and with acetone (2.7 MPa) treatment. The membrane pore sizes, determined by nitrogen adsorption/desorption were in nanofiltration range (74 angstrom) and the acetone treatment increased the average pore sizes to tight ultrafiltration range (194 angstrom) with a concomitant increase (7000%) of surface area. The water flux, also increased from zero to 25 L m(-2) h(-1) at a pressure differential of 0.45 MPa, for acetone treated membranes. Modeling of the permeance showed that the middle layer of cellulose nanofibers was responsible for the majority of the resistance to flux and the flux can be improved by increasing the porosity or decreasing the thickness of this layer. The membranes irrespective of the surface functionality showed exceptional capability (approximate to 100%) to remove Ag+, Cu2+ and Fe3+/Fe2+ ions from mirror industry effluents. Surface adsorption followed by micro-precipitation was considered as the possible mechanism of ion removal, which opens up a new generation of ultra filtration membranes with high rejection towards metal ions.
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| 9. |
- Valencia, Luis, et al.
(author)
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Nanolignocellulose extracted from environmentally undesired prosopis juliflora
- 2019
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:2, s. 4330-4338
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Journal article (peer-reviewed)abstract
- Rising sustainability demands the search of new low-market-value sources of lignocellulosic biomass as raw material for nanocellulose processing. In this paper, we accordingly propose the isolation of nanocellulose from Prosopis juliflora, an abundant but environmentally undesired tree. P. juliflora wood was powered, refined by steam explosion and bleaching, and subsequently used to isolate cellulose nanocrystals and nanofibers by means of acid hydrolysis and mechanical fibrillation. The derived nanocrystals had a rod-shaped structure with an average diameter of 20 nm and length of 150 nm, whereas the nanofibers had a diameter of 10 nm and length in micron size. Moreover, we report a simple method to isolate nanolignocellulose by using partially bleached P. juliflora as feedstock. The presence of lignin provided antioxidant and antimicrobial activity to nanocellulose, as well as hydrophobicity and increased thermal stability. The study demonstrates the successful use of P. juliflora to extract functional nanomaterials, which compensate for its environmental concern and declining market interest.
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| 10. |
- Adler, Anneli, et al.
(author)
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Lignin-first biorefining of Nordic poplar to produce cellulose fibers could displace cotton production on agricultural lands
- 2022
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In: Joule. - : Elsevier BV. - 2542-4351. ; 6:8, s. 1845-1858
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Journal article (peer-reviewed)abstract
- Here, we show that lignin-first biorefining of poplar can enable the production of dissolving cellulose pulp that can produce regenerated cellulose, which could substitute cotton. These results in turn indicate that agricultural land dedicated to cotton could be reclaimed for food production by extending poplar plantations to produce textile fibers. Based on climate-adapted poplar clones capable of growth on marginal lands in the Nordic region, we estimate an environmentally sustainable annual biomass production of ∼11 tonnes/ha. At scale, lignin-first biorefining of this poplar could annually generate 2.4 tonnes/ha of dissolving pulp for textiles and 1.1 m3 biofuels. Life cycle assessment indicates that, relative to cotton production, this approach could substantially reduce water consumption and identifies certain areas for further improvement. Overall, this work highlights a new value chain to reduce the environmental footprint of textiles, chemicals, and biofuels while enabling land reclamation and water savings from cotton back to food production.
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