Acid Hydrolysis Of Wheat Straw Research Articles

Alkaline wet oxidative pretreatment and acid hydrolysis of wheat straw for squalene and monomethyl branched chain fatty acids rich lipid production in Lentibacillus salarius BPIITR

Lignocellulosic biomass has high potential for use as a carbon substrate in microbial fermentation. However, the generation of various lignin-derived phenolic compounds, benzoic acids, and carbohydrate-derived furan aldehydes poses a major bottleneck. In this study, wheat straw was subjected to sequential alkaline wet oxidative pretreatment (AWOP) and acid hydrolysis to extract hemicellulose sugars. After statistical optimization, 251.50 mg/g total sugar (228.57 mg/g pentose, 22.93 mg/g hexose) and 19.64 mg/g hydrolysis by-products were achieved, with a theoretical pentose recovery of 89.57% and residual cellulose of 72.1%. The lignin-rich and carbohydrate-rich liquids from the AWOP treatment and acid hydrolysis, respectively, were valorised to produce squalene and branched chain fatty acid rich lipid using Lentibacillus salarius BPIITR. The lipid of 100.9 ± 3.53 and 235.75 ± 10.39 mg/g of dcw rich in squalene up to 3121.17 ± 25.49 and 676.41 ± 134.27 μg/g of lipid was produced in AWOP and acid hydrolysate, respectively. In the AWOP hydrolysate, lignin content was reduced by 63.78%, compared to a 40.18% reduction in the acid hydrolysate. GC-MS analysis of the lignin monomer and metabolites suggests the potential influence of lignin monomers on the biosynthetic pathway of squalene and carbohydrate content on the branched chain fatty acids accumulation in the halophilic bacterial lipid of L. salarius BPIITR.

An integrated biorefinery process for co-production of xylose and glucose using maleic acid as efficient catalyst

This study aims to valorize wheat straw for xylose and glucose recovery using maleic acid in the pretreatment. The process conditions of maleic acid hydrolysis of wheat straw for xylose recovery were optimized by response surface methodology, through which the maximum xylose recovery of 77.12% versus minimum furfural yield of 1.61% were achieved using 70 g/L solid-to-liquid ratio and 0.1 mol/L maleic acid for 40 min at 150 °C. Moreover, 88.58% cellulose conversion was achieved by enzymatic hydrolysis of maleic acid-pretreated wheat straw. Results showed that maleic acid was an effective pretreatment solvent for sugars recovery: 19.88 g xylose and 30.89 g glucose were respectively obtained from 100 g wheat straw due to acidic and enzymatic hydrolysis, with only 0.37 g furfural produced. This study provides a strategy for hydrolyzing wheat straw to produce fermentable sugars with low amount of degradation product.

Production of xylose from diluted sulfuric acid hydrolysis of wheat straw

The objectives of this study were to generate fermentable xylose by sulfuric acid hydrolysis of wheat straw and investigate the effect of hemicellulose removal on the physical and chemical properties of the unhydrolyzed solid residue (USR). Different reaction conditions, including concentration of sulfuric acid (COS), temperature, and time, were tested for their effects on the yield of xylose and the USR. The ideal hydrolysis conditions for xylose production were 0.5% of COS at 140 °C for 90 min, with the xylose yield of 0.185 g/g wheat straw. The Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses showed that the acid hydrolysis only caused slight changes in the functional groups and the crystal form of wheat straw at mild conditions, while higher temperature or higher COS exacerbated these changes.

Wheat straw hydrolytic pretreatment using maleic acid to enhance ethanol production from sugars

The acid hydrolysis of wheat straw was studied using a batch reactor. The hydrolysis was catalyzed by 0.01-0.09 M maleic acid for 0-50 min at 140°C-180°C. The hydrolysis kinetics of cellulose and hemicelluloses were simulated by a new model incorporating the acidity of the liquid phase. Moreover, the pH and the temperature profile during the process were included using a new modified severity factor R0*. The model parameters were calculated using nonlinear regression analysis. Process parameters investigated herein include variation in temperature, acid concentration and pH. The optimum reaction conditions resulting to maximum sugars yield were estimated according to the proposed model. For log R0* = 1.971 (0.05 M maleic acid, 180°C, 25 min) up to 18.2% w/w total glucose on cellulose basis, 91.0% w/w total xylose on xylan basis and 44.4% w/w total sugars on polysaccharides basis were obtained. The monosaccharides and oligosaccharides produced can be fermented to bioethanol. [Received: January 14, 2016; Accepted: September 26, 2016]

Wheat straw hydrolytic pretreatment using maleic acid to enhance ethanol production from sugars

The acid hydrolysis of wheat straw was studied using a batch reactor. The hydrolysis was catalyzed by 0.01-0.09 M maleic acid for 0-50 min at 140°C-180°C. The hydrolysis kinetics of cellulose and hemicelluloses were simulated by a new model incorporating the acidity of the liquid phase. Moreover, the pH and the temperature profile during the process were included using a new modified severity factor R0*. The model parameters were calculated using nonlinear regression analysis. Process parameters investigated herein include variation in temperature, acid concentration and pH. The optimum reaction conditions resulting to maximum sugars yield were estimated according to the proposed model. For log R0* = 1.971 (0.05 M maleic acid, 180°C, 25 min) up to 18.2% w/w total glucose on cellulose basis, 91.0% w/w total xylose on xylan basis and 44.4% w/w total sugars on polysaccharides basis were obtained. The monosaccharides and oligosaccharides produced can be fermented to bioethanol. [Received: January 14, 2016; Accepted: September 26, 2016]

Acid hydrolysis of wheat straw: A kinetic study

Abstract Biotechnological xylitol production can be enhanced if the needed xylose solutions can be obtained from hydrolysis of low-cost lignocellulosic wastes. The hydrolysis of wheat straw to obtain xylose solutions has a double consequence, the elimination of a waste and the generation of a value-added product. The objective of this work was to study the xylose production from wheat straw by sulphuric acid hydrolysis at 130 °C. Several mass fraction of acid (1, 2, 3, 4 or 5%) were evaluated. Kinetic models were developed to explain the variation with time of xylose, glucose, arabinose, furfural, 5-(hydroxymethyl)-2-furaldehyde and acetic acid in the hydrolysates. Optimal conditions found were a H2SO4 mass fraction of 2% at 130 °C for 29 min, which yielded a solution with xylose, 18.9 kg m−3; glucose, 3.5 kg m−3; arabinose, 3.1 kg m−3; furfural, 0.6 kg m−3; 5-(hydroxymethyl)-2-furaldehyde, 0.3 kg m−3 and acetic acid, 2.3 kg m−3. In these conditions, 99% of the hemicelluloses and 11% of the glucan were hydrolysed.

Improved sulfuric acid decrystallization of wheat straw to obtain high yield carbohydrates

Wheat straw is an abundant residue of agriculture which is increasingly considered as a feedstock for the production of fuels, energy and chemicals. The concentrated acid hydrolysis of wheat straw has been investigated in this work. Hemicellulose and cellulose have been efficiently converted into monomers of pentoses and glucose in high yields by a one-pot decrystallization-hydrolysis procedure. This process differs from usual concentrated acid biomass fractionation methodologies as a low quantity of acid is used and the supplementary use of a costly acid is not necessary to yield efficiently carbohydrates. The influence of the acid native concentration, and of the time of the decrystallization step have been studied so as to optimise yields of carbohydrates using a minimum of sulfuric acid so as to preserve a potential market value of the process. One can also imagine that this procedure will not impact dramatically the subsequent purification costs. In view of the growing importance of renewable resource-based molecules in the chemical industry, and the necessity to produce fermentable substrate for biofuels, this approach may open a new avenue for the use of wheat straw as raw material for various applications.

Lignin from Formic Acid Hydrolysis of Wheat Straw

Lignin from Formic Acid Hydrolysis of Wheat Straw

Saccharification of wheat straw for the production of alcohols

The kinetics of acid hydrolysis of wheat straw with 0.5–4.0% w/w HCl was studied at temperatures between 110 and 140°C. The experimental results obtained conformed to the following two consecutive first-order reactions: ▪ Constants K 1 and K 2 (h −1) were found to be related to the temperature (K) and the acid concentration (w/w) by the following equations: ▪ where activation energies are expressed in kJ/mol. The theoretical sugar concentrations derived from the above equations and their experimental counterparts differed by less than 10%.