Pretreatment of cotton spinning residues for optimal enzymatic hydrolysis: a case study using green solvents

ABSTRACT: The effectiveness of imidazole and ionic liquid pretreatments for the conversion of cotton spinning residues (dirty cotton residue - DCR and cotton filter powder - CFP) into soluble sugars was investigated. DCR was pretreated with imidazole using temperatures and reaction times that were arranged in a 2(2) factorial design and pretreatment performance was evaluated by enzymatic hydrolysis. High glucan to glucose and xylan to xylose yields (78.0 and 94.9 mol %) were obtained from the solids produced at 140 degrees C and 2h (center point), which provided delignification levels of 45.5% (w.v(-1)). The same pretreatment condition was applied to CFP yielding only 16.0% (w.v(-1)) of delignification, but 75.8 mol % of glucan and 95.7 mol % of xylan were converted as their corresponding monomeric sugars after enzymatic hydrolysis. Both pretreated materials were subjected to a central composite design to find the best enzymatic hydrolysis conditions regarding substrate total solids (TS) and enzyme loading. More than 40 g.L-1 glucose was obtained from both pretreated materials at 13.7% w.w(-1) TS and 20 FPU.g(-1) glucan after 96 h of hydrolysis. Ionic liquid pretreatment of the same cotton spinning residues showed moderate delignification levels, accompanied by a change in biomass crystallinity from cellulose 1 beta to cellulose II. This turned to be very important to improve enzymatic hydrolysis yields. Therefore, biomass delignification and crystallinity confirmed to be key factors governing the enzymatic saccharification of cotton spinning residues.info:eu-repo/semantics/publishedVersio

Contribution to the production and use of biomass-derived solvents : a review

ABSTRACT: In this review key processes for the synthesis of greener or more sustainable solvents derived from renewable sources (saccharides, lignocellulose and triglycerides) are discussed. It is shown that a series of platform chemicals such as glycerol, levulinic acid and furans can be converted into a variety of solvents through catalytic transformations that include hydrolysis, esterification, reduction and etherification reactions. It was also considered several aspects of each class of solvent regarding performance within the context of the reactions or extractions for which it is employed.info:eu-repo/semantics/publishedVersio

Insight into the high-pressure CO2 pre-treatment of sugarcane bagasse for a delivery of upgradable sugars

ABSTRACT: This work provides an insight into sugarcane bagasse pre-treatment carried out with greener and more sustainable CO2/H2O system. Temperatures and residence times at a fixed initial CO2 pressure were studied to verify their effects on pre-treatment efficiency with regard to the chemical composition of both water-soluble and water-insoluble fractions as well as to the susceptibility of the latter to enzymatic hydrolysis at high total solids. Also, trends in enzymatic hydrolysis were analysed in function of biomass crystallinity. This work provides an integrated approach in the analysis of upgradable sugars that are released as a result of pre-treatment and enzymatic hydrolysis. At optimal pre-treatment conditions, 17.2 g.L-1 sugars were released in the water-soluble fraction mainly as pentoses in monomeric and oligomeric forms. The enzymatic hydrolysis of solids produced at these pre-treatment conditions gave 76.8 g.L-1 glucose in the substrate hydrolysate. The overall sugar yield delivered in both pre-treatment and enzymatic hydrolysis was 73,9 mol%. These results were compared to the chemical effect of hydrothermal and/or physico-chemical effects of N-2-aided hydrothermal processes and showed that the greener processing of biomass pre-treatment with CO2 is advantageous for the integrated valorisation of industrial residues and delivery of upgradable sugars within the biorefinery concept.info:eu-repo/semantics/publishedVersio

The green biorefinery concept for the valorisation of pistachio shell by high-pressure CO2/H2O system

ABSTRACT: The use of high-pressure CO2/H2O in valorisation of pistachio shell to produce hemicellulose-derived, oligomeric and monomeric sugars and their further transformation to furfural as well as enzymatic transformation of cellulose-rich solids is presented in this work. Different pre-treatment conditions i.e. temperature ranged from 160 to 200 degrees C; reaction time varied between 0 and 30 min and liquid to solid mass ratio between 4 and 8 with constant initial pressure of CO2 of 50 bars were examined. At the optimal pre-treatment conditions, the concentrations of xylose and xylo-oligosaccharide were of 1.7 and 35.5 g/L. Furthermore, this work demonstrates the high-pressure CO2 catalysed production of furfural in an aqueous/tetrahydrofuran system. For model solution containing a mixture of xylose and acetic acid, the optimised furfural yield was as high as 53.3 mol%, while for real sample of hemicellulose hydrolysate, the furfural yield of 39.6 mol% and the selectivity of 40.0 mol% were obtained. Additionally, quantitative glucan to glucose conversion by enzymatic hydrolysis of pre-treated cellulose-rich biomasses was achieved.info:eu-repo/semantics/publishedVersio

Male-Produced Sex Pheromone of the Carrion Beetles, Oxelytrum discicolle and its Attraction to Food Sources

Abstract Carrion beetles are part of the great diversity of insects collected on cadavers. In Brazil, beetles of the genus Oxelytrum have great forensic importance in post mortem interval (PMI) estimation. We investigated the system of chemical communication in the attraction of these necrophagous beetles. Gas chromatographic analysis (GC) of female and male aeration extracts revealed the presence of two male-specific compounds, produced in a ratio of 94:6. Bioassays showed that the combination of male produced volatiles and the odor of a food source (carcass volatiles) were attractive to females. Mass and infrared spectral analyses of the male-specific compounds suggested that they were both unsaturated hydrocarbons. Several microderivatizations were carried out with the natural products, and the target structures were identified as (Z)-1,8-heptadecadiene (major) and 1-heptadecene (minor). The structure of the minor component was assigned by co-injection with a commercial standard. A seven-step synthesis was developed to synthesize (Z)-1,8-heptadiene, which co-eluted with the major natural product on three different GC stationary phases. Y-tube olfactometer assays showed that the mixture of synthetic standards in the naturally occurring proportion was slightly attractive to females. The results contribute both to the understanding of the chemical ecology of O. discicolle and to its potential to improve the accuracy of PMI estimation

Enzymatic Hydrolysis of Steam-Treated Sugarcane Bagasse: Effect of Enzyme Loading and Substrate Total Solids on Its Fractal Kinetic Modeling and Rheological Properties

Rheological studies and fractal kinetic modeling were applied to investigate the enzymatic hydrolysis of steam-exploded sugarcane bagasse (195 °C, 7.5 min) using Cellic CTec3 cellulases (Novozymes). Initially, a central composite rotatable design (CCRD) was performed to evaluate the effect of different enzyme loadings and substrate total solids (TS) on both substrate apparent viscosity and kinetic parameters of enzymatic hydrolysis. Hydrolysis at 20% TS for 12 and 96 h using 38.6 FPU g^–1 glucan released 52 and 110 g L^–1 glucose equivalents from the steam-exploded material, respectively, with cellobiose being always below 1.7% of these readings. Fractal kinetic modeling provided a good fit of both glucan and xylan conversions, and the fractal kinetic parameters <i>k</i> and <i>h</i> had a strong correlation with changes in both substrate TS and enzyme loading. At the center point of the CCRD, Cellic CTec3 caused a decrease of 1 order of magnitude in the substrate apparent viscosity at every 6 h of hydrolysis. Cellic HTec3 had a boosting effect on the enzymatic hydrolysis of cane bagasse glucans regardless of the low hemicellulose content of the steam-treated material. Glucan hydrolysis was improved by 8% when 10% Cellic HTec3 was added to a hydrolysis mixture containing Cellic CTec3 at 38.6 FPU g^–1 glucan. With this, a total production of 120 g L^–1 glucose was achieved at 72 h using 20% TS