Bioethanol production from agricultural wastes: An overview

Production of bioethanol from lignocellulosic materials via the biochemical pathway: a review.

A review of lignocellulose bioconversion using enzymatic hydrolysis and synergistic cooperation between enzymes--factors affecting enzymes, conversion and synergy.

The replacement of fossil resources that currently provide more than 90% of our energy needs and feedstocks of the chemical industry in combination with reduced emission of carbon dioxide is one of the most pressing challenges of mankind. Biomass as a globally available resource has been proposed as an alternative feedstock for production of basic building blocks, which could partially or even fully replace the currently utilized fossil-based ones in well-established chemical processes. The destruction of lignocellulosic feed followed by oxygen removal from its cellulose and hemicellulose content by catalytic processes results in the formation of initial platform chemicals (IPCs). However, their sustainable production strongly depends on the availability of resources, their efficient or even industrially viable conversion processes, and replenishment time of feedstocks. Herein, we overview recent advances and developments in catalytic transformations of the carbohydrate content of lignocellulosic biomass ...

Catalytic Conversion of Carbohydrates to Initial Platform Chemicals: Chemistry and Sustainability

Bioethanol has been identified as the mostly used biofuel worldwide since it significantly contributes to the reduction of crude oil consumption and environmental pollution. It can be produced from various types of feedstocks such as sucrose, starch, lignocellulosic and algal biomass through fermentation process by microorganisms. Compared to other types of microoganisms, yeasts especially Saccharomyces cerevisiae is the common microbes employed in ethanol production due to its high ethanol productivity, high ethanol tolerance and ability of fermenting wide range of sugars. However, there are some challenges in yeast fermentation which inhibit ethanol production such as high temperature, high ethanol concentration and the ability to ferment pentose sugars. Various types of yeast strains have been used in fermentation for ethanol production including hybrid, recombinant and wild-type yeasts. Yeasts can directly ferment simple sugars into ethanol while other type of feedstocks must be converted to fermentable sugars before it can be fermented to ethanol. The common processes involves in ethanol production are pretreatment, hydrolysis and fermentation. Production of bioethanol during fermentation depends on several factors such as temperature, sugar concentration, pH, fermentation time, agitation rate, and inoculum size. The efficiency and productivity of ethanol can be enhanced by immobilizing the yeast cells. This review highlights the different types of yeast strains, fermentation process, factors affecting bioethanol production and immobilization of yeasts for better bioethanol production.

https://cyberleninka.org/article/n/143136.pdf

Yeasts in sustainable bioethanol production: A review.

Four commonly used chemical pretreatment processes based on dilute acid, lime, aqueous ammonia steeping followed by dilute acid hydrolysis, and sodium hydroxide, were evaluated to provide comparative performance data. An obverse correlation between lignin removal and enzymatic digestibility of pretreated corn stover was observed. Compared with other three pretreatments, pretreatment of corn stover with 2% NaOH substantially increased the lignin removal and enhanced the accessibility and digestibility of cellulose. The hydrolysis yield of NaOH-pretreated corn stover reached 81.2% by 48 h at 8.0% substrate concentration and cellulase dosage of 20 FPU g −1 substrate. Chemical analysis showed that the enzymatic hydrolysate from NaOH-pretreated corn stover contained higher content of fermentable sugars and less inhibitors, which is suitable for subsequent fermentation process to produce ethanol. The research results are meaningful in bioconversion and utilization of renewable lignocellulosic biomass.

Jing Zhao

Papers

Comparison of four different chemical pretreatments of corn stover for enhancing enzymatic digestibility

Enzymatic hydrolysis of maize straw polysaccharides for the production of reducing sugars

Simultaneous saccharification and fermentation of alkaline-pretreated corn stover to ethanol using a recombinant yeast strain

Bioconversion of corn stover hydrolysate to ethanol by a recombinant yeast strain