7 results
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2. Comparison of organosolv and hydrotropic pretreatments of eucalyptus for enhancing enzymatic saccharification.
- Author
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Mou H and Wu S
- Subjects
- Adsorption, Cellulase metabolism, Crystallization, Eucalyptus drug effects, Glucose analysis, Hydrolysis, Lignin chemistry, Spectroscopy, Fourier Transform Infrared, Surface Properties, Biotechnology methods, Carbohydrate Metabolism drug effects, Eucalyptus chemistry, Solvents pharmacology, Water pharmacology
- Abstract
The objective of this study was to investigate the effects of organosolv and hydrotropic pretreatments on improving enzymatic hydrolysis of eucalyptus. The chemical composition of the fiber surface was analyzed using X-ray photoelectron spectroscopy (XPS) to determine the surface characteristics of pretreated eucalyptus. Other than the significant decrease of surface coverage by lignin, hydrotropic pretreatment was more effective in removing the lignin and xylose from fiber cell walls than organosolv pretreatment. The restriction of acetyl and phenolic groups in pretreated substrates was typically eliminated by hydrotropic pretreatments. Moreover, fiber structure and morphology after pretreatments were more suitable for enzymatic hydrolysis. Cellulase adsorption capacity was notably improved by hydrotropic pretreatment, which indicating the better enzyme accessibility of cellulose in pretreated substrates. Eventually, higher glucose yield was obtained with hydrotropic pretreatment. In addition, the precipitated lignin as an important by-product of pretreatments was characterized by Fourier transforms infrared spectroscopy (FTIR) also., (Copyright © 2016 Elsevier Ltd. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
3. The impact of glycerol organosolv pretreatment on the chemistry and enzymatic hydrolyzability of wheat straw.
- Author
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Sun FF, Wang L, Hong J, Ren J, Du F, Hu J, Zhang Z, and Zhou B
- Subjects
- Hydrolysis, Plant Components, Aerial chemistry, Cellulase chemistry, Glycerol chemistry, Lignin chemistry, Organic Chemicals chemistry, Solvents chemistry, Triticum chemistry
- Abstract
Given that the glycerol organosolv pretreatment (GOP) can effectively improve the hydrolyzability of various lignocellulosic substrates, physicochemical changes of the substrate before and after the pretreatment was characterized to elucidate what is responsible for it. The effect of GOP on the main components and hydrolyzability of wheat straw was revisited. Results demonstrate that the GOP should be a promising candidate for the current pretreatment. Then the composition and structure of substrates was measured at multi-dimensional scales by using various analytic equipment such as TGA, SEM, AFM, CLSM, FT-IR, XRD and solid-state CP/MAS (13)C NMR. This paper reports some new insights on the mechanism behind that, which can be beneficial for further development, optimization, and scale-up of the GOP process., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
4. Extractive-transesterification of algal lipids under microwave irradiation with hexane as solvent.
- Author
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Martinez-Guerra E, Gude VG, Mondala A, Holmes W, and Hernandez R
- Subjects
- Catalysis drug effects, Chlorella drug effects, Chlorella metabolism, Esterification drug effects, Temperature, Time Factors, Hexanes pharmacology, Lipids isolation & purification, Microwaves, Solvents pharmacology
- Abstract
This study describes the use of microwaves (MW) for enhanced extractive-transesterification of algal lipids from dry algal biomass (Chlorella sp.). Two different single-step extractive-transesterification methods under MW irradiation were evaluated: (1) with ethanol as solvent/reactant and sodium hydroxide catalyst; and (2) with ethanol as reactant and hexane as solvent (sodium hydroxide catalyst). Biodiesel (fatty-acid-ethyl-esters, FAEE) yields from these two methods were compared with the conventional Bligh and Dyer (BD) method which followed a two-step extraction-transesterification process. The maximum lipid yields for MW, MW with hexane and BD methods were 20.1%, 20.1%, and 13.9%, respectively; while the FAEE conversion of the algal lipids were 96.2%, 94.3%, and 78.1%, respectively. The algae-biomass:ethanol molar ratio of 1:250-500 and 2.0-2.5% catalyst with reaction times around 6min were determined as optimum conditions for both methods. This study confers that the single-step non-conventional methods can contribute to higher algal lipid and FAEE yields., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2014
- Full Text
- View/download PDF
5. Regioselective enzymatic undecylenoylation of 8-chloroadenosine and its analogs with biomass-based 2-methyltetrahydrofuran as solvent.
- Author
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Gao WL, Liu H, Li N, and Zong MH
- Subjects
- 2-Chloroadenosine metabolism, Enzyme Stability, Enzymes, Immobilized, Nucleosides chemistry, Nucleosides metabolism, Penicillium enzymology, Stereoisomerism, Substrate Specificity, Temperature, 2-Chloroadenosine analogs & derivatives, Biomass, Furans metabolism, Lipase metabolism, Solvents metabolism
- Abstract
2-Methyltetrahydrofuran (MeTHF), a biomass-derived compound, is a promising medium for biocatalysis and organometallic reactions. The regioselective acylation of 8-chloroadenosine (8-Cl-Ado) and its analogs was carried out in MeTHF with immobilized Penicillium expansum lipase. The lipase displayed more than twofold higher catalytic activity and much better thermostability in MeTHF than in other organic solvents and co-solvent systems. The optimum reaction medium, enzyme dosage, molar ratio of viny ester to nucleoside and reaction temperature for the enzymatic acylation of 8-Cl-Ado were MeTHF, 25 U/mL, 7.5 and 35 °C, respectively, under which the desirable 5'-O-undecylenoyl-8-Cl-Ado was obtained with a yield of 95% and a regioselectivity of >99% in 3 h. In addition, the lipase catalyzed regioselective undecylenoylation of other purine nucleosides, producing 5'-undecylenic acid esters with moderate to high yields (63-94%) and excellent 5'-regioselectivities (94->99%). Use of biomass-derived solvents might open up novel opportunities for sustainable and greener biocatalytic processes., (Copyright © 2012 Elsevier Ltd. All rights reserved.)
- Published
- 2012
- Full Text
- View/download PDF
6. A facile whole-cell biocatalytic approach to regioselective synthesis of monoacylated 1-β-D-arabinofuranosylcytosine: influence of organic solvents.
- Author
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Li XF, Lu ZH, Zhao GL, Wu H, and Yu YG
- Subjects
- Acylation, Catalysis, Cytarabine isolation & purification, Freeze Drying, Pseudomonas fluorescens isolation & purification, Cytarabine chemical synthesis, Organic Chemicals chemistry, Pseudomonas fluorescens chemistry, Solvents chemistry
- Abstract
The lyophilized Pseudomonas fluorescens cell was an efficient alternative catalyst to enzymes for highly regioselective acylation of a polar nucleoside, 1-β-D-arabinofuranosylcytosine (ara-C). The cells showed an evident solvent dependence in the reaction. Among the tested solvents except for acetonitrile-pyridine, catalytic activity of the cells clearly increased with increasing the polarity of the organic solvents used. Among all the tested solvents both pure and binary, the best results were observed in isopropyl ether-pyridine system, in which the catalyst also showed good thermal and operational stabilities. For the biocataylsis in isopropyl ether-pyridine, the optimal isopropyl ether concentration, water content, acyl donor/ara-C ratio, biocatalyst dosage and reaction temperature were 30% (v/v), 4%, 45, 50mg/mL and 30 °C, respectively, under which the initial rate, yield and 5'-regioselectivity were 2.93 mM/h, 77.1% and 97.3%, respectively. The bacterial cells exhibited comparable 5'-regioselectivity to the expensive immobilized enzyme, which could also have environmental and cost advantages., (Copyright © 2012 Elsevier Ltd. All rights reserved.)
- Published
- 2012
- Full Text
- View/download PDF
7. Effect of pulping variables with dimethyl formamide on the characteristics of bagasse-fiber.
- Author
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Rezayati-Charani P and Mohammadi-Rovshandeh J
- Subjects
- Iran, Materials Testing, Pressure, Temperature, Time Factors, Cellulose chemistry, Dimethylformamide chemistry, Lignin chemistry, Paper, Solvents chemistry
- Abstract
Organosolv pulping of bagasse was conducted following a central composite design using a two-level factorial plan involving three pulping variables (temperature: 190-210 degrees C, time: 120-180 min, organic solvent ratio: 40-60% dimethyl formamide). Responses of pulp and handsheets properties to the process variables were analyzed using statistical software (MINITAB 14). Using values of the independent variables the variation ranges considered provided the following optimum values of the dependent variables: 82.7% (yield), 92.9 (kappa number), 1.403% (ash), 370 ml (freeness), 6290 m (breaking length), 9.4 (folding endurance), 5.955 mN m2 g(-1) (Tear index) and 2.811 kN g(-1) (Burst index) for pulps and handsheets. Results showed that acceptable physical and mechanical properties of pulps and papers similar the pulp used for bleaching could be achieved at 210 degrees C for 150 min and 50% DMF. These are the most suitable conditions for obtaining paper sheets with a high breaking length, tear and burst indices. Also bagasse could be pulped with ease to about 55.72% yield with kappa number approximately 35. The cooking temperature was a significant factor while the DMF ratio and cooking time were not as important in term of the properties of the resultant pulps and papers.
- Published
- 2005
- Full Text
- View/download PDF
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