Dilute Acid Hydrolysis of Wheat Straw Oligosaccharides

Abstract

The dilute acid posthydrolysis of wheat straw hemicellulosic oligosaccharides obtained by autohydrolysis was evaluated. An empirical model was used to describe the effect of catalyst concentration (sulfuric acid, 0.1-4% w/w) and reaction time (0-60 min) based on data from a Doehlert experimental design. Catalyst concentration is the main variable influencing posthydrolysis performance, as both its linear and quadratic coefficients are statistically significant for the majority of the studied variables, namely, the ones related to sugar and byproducts production. Reaction time influences xylose and furan derivatives concentrations but not phenolics or acetic acid content. Catalyst concentration and reaction time interact synergistically, minimizing sugar recovery and promoting furan derivatives production. Based on the proposed models, it was possible to delimit an operational range that enables to obtain high monosaccharides recovery together with a slight decrease in inhibitors content as compared to the standard acid hydrolysis treatment. Furthermore, this is achieved with up to 70% less acid spending or considerable savings on reaction time.

Hydrolysis of Oligosaccharides Over Solid Acid Catalysts: A Review

“…[76] The importance of impurities for the catalyst activity and stability present in, for example, autohydrolysis effluents has hardly been studied in the literature. It is important to note that oligosaccharide liquors contain carboxylic acids, mainly acetic acid coming from acetyl groups of hemicelluloses, furfural, HMF, [77] ex-lignin organic compounds (e.g., phenols, terpenes), [78] but also inorganic compounds (e.g., ions released during catalyst leaching) and, eventually, proteins coming from the raw lignocellulosic material. All these compounds can interact with acid catalysts and increase their deactivation, for example, by an ion-exchange reaction between the dissolved cations and the Brønsted acid sites of the catalyst, by poisoning, or by favoring the leaching of mineral compounds from the catalysts.…”

Wheat Straw Autohydrolysis: Process Optimization and Products Characterization

“…In fact, the generation of sugar degradation products was quite low, which is an advantage that enables the utilization of autohydrolysis to produce XOS-rich liquors that can be used both to obtain purified XOS mixtures (which can be potential prebiotic ingredients) or for the production of pentoses-rich culture media, e.g., using a enzymatic hydrolysis or a dilute acid post-hydrolysis as specifically optimized for wheat straw oligosaccharides [34].…”

A review of the potential of pretreated solids to improve gas biofuels production in the context of an OFMSW biorefinery

“…In addition to cellulose, hemicellulose complex is typically present in the waste feed, and the action of several enzymes, such as endoxylanases, exoxylanases, β‐xylosidases, as well as other enzymes that contribute to the hydrolysis (i.e. α‐glucuronidases, α‐arabinofuranosidases and feruloyl esterease) are required to complete their degradation . In recent work, Escamilla‐Alvarado et al pretreated the fermented organic wastes with cellulases derived from Trichoderma reesei MCG 80 to evaluate the bioH 2 potential .…”