Search

Sugarcane bagasse is abundant agro-industrial waste that can be potentially utilized as a source of valuable compounds and biopolymers. In the present study, sugarcane bagasse from Brazil was fractionated employing an environmentally friendly hydrotropic process. Several treatments were carried out at 150 and 170 °C and dwell times of 60 and 120 min using unmodified 30% hydrotropic solutions as well as the solutions acidified with formic acid. The major produced fraction was cellulose pulp obtained with the yield of 44–67% (bagasse based) and the cellulose content of 60–92%. Lignins dissolved during the treatments were isolated from the spent solutions by dilution with water and filtration. The yields of the lignins were 11.8–14.7% (bagasse based) and their purity ranged from 88 to 94%. Generally, the purity of both fractions and the yield of lignin were higher at more severe process conditions. However, the more severe conditions resulted in lower average molar masses of the lignins and lower intrinsic viscosity values of the cellulose fractions. The composition of the spent solutions also varied with the treatment conditions, and, besides the lignins, they contained different amounts of dissolved hemicelluloses, sugar monomers, furfural and acetic and formic acids. The results of the present study showed that the hydrotropic process could be successfully applied for the valorization of sugarcane bagasse by its fractionation into lignin, cellulose and other products. [ABSTRACT FROM AUTHOR]

Highlights • Hemicelluloses were obtained via alternative wood biorefining strategies. • Hemicelluloses were compared as biobased emulsion stabilizers. • Sustainable alkyd paint emulsions were characterized. • Natural hemicellulose-rich isolates showed promising functionality. • The crude technical hemicellulose fractions were the most efficient stabilizers. Abstract Wood biorefining currently involves large-scale industrial processes where a notable portion of raw materials, namely hemicelluloses and lignin, are either lost with the process water, degraded, or burnt for energy. Value-added utilization of polymeric hemicelluloses is challenging due to their intermediate molar mass and the presence of other wood components, such as phenolic residues or wood extractives. Oil-in-water (O/W) emulsions represent a diverse and abundant class of applications in which the natural properties of wood hemicelluloses are beneficial. In the current work, we present highly promising new technical alkyd paint emulsion systems stabilized with hardwood glucuronoxylans (GX) and softwood galactoglucomannans (GGM). Samples from three isolation methods and their further fractionation by ethanol precipitation were systematically compared with regard to hemicellulose composition, interfacial activity, and functionality in emulsions. Emulsification of alkyd resins was successful with both GX and GGM obtained by various biorefining strategies. The highest emulsion stability over storage was achieved using crude non-purified GX and GGM fractions, and was correlated with the presence of phenolic compounds and extractives, interfacial activity, and small droplet size. Hardwood GX and softwood GGM are envisioned as natural emulsifiers of alkyd O/W emulsions, which are examples of diverse and abundantly-used technical dispersions. This study can be utilized as a guideline for targeted extraction of hemicelluloses with desired functionality, and as a protocol for developing environmentally-compatible industrial dispersions. [ABSTRACT FROM AUTHOR]

Abstract: The changes in the amount and composition of suberin monomers of Scots pine outer bark, which is grown natively in Turkey, was investigated as a function of growing altitude. Samples were taken from every 100m to 1300m which was the highest point of the sampling area. While the total amount of suberin monomers is varied within the range 17.56–47.20mg/g, there was no correlation between total amount and altitude. Total amount of alkanols of suberin monomers decreased when the altitude increased. Alcohol 24:0 was seen as the dominant constituent and its amount decreased from 100m to 1300m. There was not a clear change in the total amount of alkanoic, dioic and hydroxy acids. Acid 1,18-hydroxy-18:1 and acid 1,18-dioic-18:1 were determined as the main compounds in all samples. [Copyright &y& Elsevier]

Abstract: Acid hydrolysis, acid methanolysis, and enzymatic hydrolysis were compared for depolymerization of five different plant materials containing uronic acids. The analyzed plant materials were oat spelt, wheat straw, spruce thermomechanical pulp, aspen stemwood, and totally chlorine-free (TCF) bleached hardwood kraft pulp. Furthermore, GC (using both HP-1 and HP-5 capillary columns and FID and MSD detectors), HPAEC-PAD, and HPAEC-Borate techniques were compared for subsequent analysis of the released monosaccharides. It was shown that acid methanolysis combined with GC analysis is a convenient method for obtaining the sugar unit composition and amount of non-crystalline polysaccharides in different plant materials. The methanolysis method was generally superior to the hydrolysis method for xylan- and uronic acid-containing samples. However, acid and enzymatic hydrolysis showed the highest recoveries for bleached chemical pulp samples. Acid hydrolysis is also required for crystalline polysaccharides, but the strong acid conditions evidently lead to degradation of labile sugars. The plant methanolysates were not suitable as such for analysis on an HPAEC-PAD system. For analysis of the total amount of sugar units, hence including cellulose, other non-crystalline hemicelluloses, and pectins, a combination of the methanolysis and hydrolysis methods is recommended. [Copyright &y& Elsevier]

• Successive chemical treatments were optimized to purify cellulose fibers from raw Ampelodesmos mauritanicus. • Nanocellulose substrates were isolated from Ampelodesmos mauritanicus by mechanical treatment or acid hydrolysis. • TEMPO-mediated oxidation pretreatment was used for the production of cellulose nanofibrils with controled degree of oxidation. • Cellulose nanocrystals and cellulose nanofibrils isolated from Ampelodesmos mauritanicus form stable suspensions in water. In this work nanocellulose substrates e. g. cellulose nanofibrils and nanocrystals were isolated from an abundant renewable resource Ampelodesmos mauritanicus fibers. Cellulose nanocrystals CNCs were isolated from the fibers by means of acid hydrolysis while cellulose nanofibrils (CNFs) were isolated by combination of TEMPO-mediated oxidation and mechanical shearing using high-pressure homogenizer. The chemical composition of Ampelodesmos mauritanicus fibers was analyzed prior to the isolation of the different nanocellulose substrates in order to optimize their extraction processes. The morphology, geometry, and distribution of the cellulosic nanoparticles were performed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the crystalline structure and the crystallite size were evaluated by X-ray diffraction (XRD). The surface charge of CNCs and the degree of oxidation of CNFs were examined by Zeta potential and conductometric titration. The nanocellulose substrates extracted from Ampelodesmos mauritanicus fibers exhibit a diameter of 5.64 ± 1.5 nm and length of 108.95 ± 13.7 nm for CNCs and 6.1 ± 1.5 nm and a few micrometers for CNFs. [ABSTRACT FROM AUTHOR]