Multistep Structural and Chemical Evaluation of Sugarcane Baggase, Pretreated With Alkali for Enhancing the Enzymatic Saccharification by Cellulase and Xylanase of the Pseudomonas sp. CVB-10 (MK443365) and Bacillus paramycoides T4 (MN370035) Mix-Culture System

The enzymatic saccharification of sugarcane bagasse was significantly increased by alkali pretreatment under mild conditions. The effectiveness of different concentrations of alkali and acid pretreatment of sugarcane bagasse for improving the enzymatic saccharification of lignocellulose has been evaluated. The sugarcane bagasse was characterized to contain 39.52% celluloses, 25.63% hemicelluloses, and 30.36% lignin. After that, sugarcane bagasse was pretreated with 5 and 10% of H2SO4 and NaOH at 121°C for 60 min. FTIR, XRD, and SEM analyses also showed significant molecular and surface structure changes of the sugarcane bagasse with 10% NaOH. Maximum saccharification was 489.5 mg/g from 10% NaOH pretreatment followed by 322.75, 301.25, and 276.6 mg/g from 10% H2SO4, 5% NaOH, and 5% H2SO4, respectively, which were 55.1, 32.0, 27.1, and 20.6 times higher than the that of the control. Cellulase and xylanase produced by Pseudomonas sp. CVB-10 (MK443365) and Bacillus paramycoides T4 (MN370035) were used to hydrolyze the pretreated bagasse, and the optimal condition was determined to be 30 h of the enzymatic reaction with the 3:1 ratio of enzymes under the temperature of 55°C, pH 5.0, and substrate concentration of 3%, leading to celluloses and hemicelluloses conversion in the enzymatic hydrolysis/saccharification that is more proficient.

Enhancement of Delignification and Glucan Content of Sugarcane Bagasse by Alkali Pretreatment for Bioethanol Production

The current work aimed to enhance the delignification of sugarcane bagasse (SCB) for bioethanol production. The optimization of alkali (sodium hydroxide) pretreatment parameters such as concentration and residence time was carried out by the Taguchi method using L16 orthogonal array with two factors and four levels. Sugarcane bagasse powder was mixed with sodium hydroxide (NaOH) solution (0.5-2 wt.%) and heated in an autoclave at 121°C and at varied times (30-120 min). From the statistical analysis of data, it was observed that delignification and glucan increased with the increased concentration and short time. The optimum parameters of NaOH pretreatment were 2 wt.% of NaOH concentration and 30 minutes of residence time. At the optimum conditions, 86.8% delignification and 46.6% glucan content of SCB were obtained. Thus, alkali pretreatment optimized by Taguchi design is the effective method to remove lignin and to increase cellulose or glucan content in sugarcane bagasse for facilitating the further catalytic hydrolysis in bioethanol production.

Isolation and Fractionation of the Tobacco Stalk Lignin for Customized Value-Added Utilization

The value-added utilization of tobacco stalk lignin is the key to the development of tobacco stalk resources. However, the serious heterogeneity is the bottleneck for making full use of tobacco stalk lignin. Based on this, lignin was separated from tobacco stalk through hydrothermal assisted dilute alkali pretreatment. Subsequently, the tobacco stalk alkaline lignin was fractionated into five uniform lignin components by sequential solvent fractionation. Advanced spectral technologies (FT-IR, NMR, and GPC) were used to reveal the effects of hydrothermal assisted dilute alkali pretreatment and solvent fractionation on the structural features of tobacco stalk lignin. The lignin fractions extracted with n-butanol and ethanol had low molecular weight and high phenolic hydroxyl content, thus exhibiting superior chemical reactivity and antioxidant capacity. By contrast, the lignin fraction extracted with dioxane had high molecular weight and low reactivity, nevertheless, the high residual carbon rate made it suitable as a precursor for preparing carbon materials. In general, hydrothermal assisted dilute alkali pretreatment was proved to be an efficient method to separate lignin from tobacco stalk, and the application of sequential solvent fractionation to prepare lignin fractions with homogeneous structural features has specific application prospect.

The improvement of physicomechanical, flame retardant, and thermal properties of lignocellulosic material filled polymer composites

In this study, the effects of alkali and silane coupling agents and coir fiber (CF) loading on the fundamental properties of the CF-filled polypropylene (PP) composites were investigated. Mechanical properties of the PP/CF composites, such as tensile strength, tensile modulus, impact strength, and water absorption were increased by the increase of the CF loading. The inclusion of 3-aminopropyl trimethoxy silane (ATS) and tetramethoxy orthosilicate (TOS) after the alkali pretreatment for the CF increased all the mechanical properties and water desorption of the resulting composites. This trend was more evident with the increase in CF loading. The best results were obtained for PP/TOS composites as compared to other composites. SEM images of fractured samples show improved adhesion between CF and PP matrix after treatment with ATS and TOS. The horizontal rate of combustion is significantly reduced with the inclusion of Mg(OH)2 in PP/ATS and PP/TOS composites. DSC results show improved crystallization temperature, melting temperature, and melting enthalpy as compared with virgin PP. The addition of ATS and TOS after the alkali pretreatment improved the thermal stability of the resultant composites. TOS-modified CF composites showed better resistance than ATS-modified CF composites in water medium.

Extraction and Characterization of Cellulose Nanowhiskers from TEMPO Oxidized Sisal Fibers

Cellulose nanowhiskers as one kind of renewable and biocompatible nanomaterials evoke much interest because of its versatility in various applications. Herein, the sisal cellulose nanowhiskers with length of 100–500 nm, ultrathin diameter of 6–61 nm, high crystallinity of 74.74 % and C6 carboxylate groups converted from C6 primary hydroxyls were prepared via a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)/NaBr/NaClO system selective oxidization combined with mechanical homogenization. The effects of sodium hydroxide concentration in alkali pretreatment on the final sisal cellulose nanowhiskers were explored. It was found that with the increase of sodium hydroxide concentration, the sisal fiber crystalline type would change from cellulose I to cellulose II. The versatile sisal cellulose nanowhiskers would be particularly useful for applications in the nanocomposites as reinforcing phase, as well as in tissue engineering, filtration, pharmaceutical and optical industries as additives.

Effect of Pretreatments on Wettability and Dyeing Property of Cotton Fibers in an Environmentally Friendly Dyeing System

To investigate the influence of cotton wettability on its dyeing properties in a silicone non-aqueous dyeing system, alkali pretreatment was performed before dyeing. The dyeing properties and dyeing kinetics of reactive dyes in the non-aqueous system and a conventional dyeing system were compared. Alkali pretreatment significantly improved the wettability of cotton fiber by removing wax and pectin. The adsorption rate of dye increased with increased cotton fiber wettability using the non-aqueous system, while it barely changed using the conventional system. Pseudo-second-order kinetics fit well with dye adsorption for both systems. Dye fixation improved by 30% at a concentration of 2% owf, along with better levelness and color depth of the dyed cotton fiber, using the silicone non-aqueous system without salts and dispersants.