Model of using Vietnamosasa pusilla as starting material for the production of ethanol and xylitol

Abstract

Lignocellulosic biomass can be used as a renewable and sustainable energy source to help reduce the consequences of global warming. In the new energy age, the bioconversion of lignocellulosic biomass into green and clean energy displays remarkable potential and makes efficient use of waste. Bioethanol is a biofuel that can reduced reliance on fossil fuels while minimizing carbon emissions and increasing energy efficiency. Various lignocellulosic materials and weed biomass species have been selected as potential alternative energy sources. Vietnamosasa pusilla, a weed belonging to the Poaceae family, contains more than 40% glucan. However, research on the applications of this material is limited. Thus, we aimed to achieve maximum fermentable glucose recovery and bioethanol production from V. pusilla. Two pretreatment reagents were applied, H3PO4 (phosphoric acid) and NaOH (sodium hydroxide), to disrupt the recalcitrant structure of the lignocellulosic biomass.

First section, V. pusilla feedstocks were treated with varying concentrations (70%, 75%, 80%, and 85%) of H3PO4 and then subjected to enzymatic hydrolysis. The results indicated that after pretreatment with different concentrations of H3PO4, the glucose recovery and digestibility at each concentration were markedly enhanced. Moreover, 87.5% of cellulosic ethanol was obtained from V. pusilla biomass hydrolysate medium without detoxification.

In the next section, the V. pusilla feedstocks were again pretreated by NaOH pretreatment-assisted autoclaving. The V. pusilla enzymatic hydrolysate was used as a substrate for bioethanol and xylitol synthesis. After treating the feedstock with varying concentrations (1%, 2%, 3%, and 4%) of NaOH at different temperatures (110 °C, 120 °C, and 130 °C), the glucose and xylose recovery yields were substantially higher than those of the untreated material. The hydrolysate generated by enzymatic hydrolysis was fermented into bioethanol using Saccharomyces cerevisiae TISTR 5339. The liquid byproduct of ethanol production was utilized by Candida tropicalis TISTR 5171 to generate xylitol.

Overall, our findings reveal that V. pusilla biomass can be introduced into sugar-based biorefineries to produce biofuels and other valuable chemicals.

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