The Interplay of Autoclaving with Oxalate as Pretreatment Technique in the View of Bioethanol Production Based on Corn Stover.

Ali Hamdy,Rehab Ali,Hesham Hamad,Sara Abd Elhafez

doi:10.3390/polym13213762

Ali Hamdy, Rehab Ali + Show 2 more

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https://doi.org/10.3390/polym13213762

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Abstract

Bio-based treatment technologies are gaining great interest worldwide, and significant efforts are being afforded to develop technology for the use of lignocellulosic biomass. The potential of corn stover (CS) as a feedstock for bioethanol production was investigated by creating an optimal pretreatment condition to maximize glucose production. The current study undertook the impact of novel physico-chemical pretreatment methods of CS, i.e., autoclave-assisted oxalate (CSOA) and ultrasound-assisted oxalate (CSOU), on the chemical composition of CS and subsequent saccharification and fermentation for bioethanol production. The delignification was monitored by physicochemical characterizations such as SEM, XRD, FTIR, CHNs, and TGA. The results evidenced that delignification and enzymatic saccharification of the CS pretreated by CSOA was higher than CSOU. The optimum enzymatic saccharification operating conditions were 1:30 g solid substrate/mL sodium acetate buffer at 50 °C, shaking speed 100 rpm, and 0.4 g enzyme dosage. This condition was applied to produce glucose from CS, followed by bioethanol production by S. cerevisiae using an anaerobic fermentation process after 72 h. S. cerevisiae showed high conversion efficiency by producing a 360 mg/dL bioethanol yield, which is considered 94.11% of the theoretical ethanol yield. Furthermore, this research provides a potential path for waste material beneficiation, such as through utilizing CS.

Highlights

According to the UN sustainable development goals and the challenges of the energy shortage, the utilization of agricultural perspectives as renewable energy resources is a target for a sustainable economy [1]
Even though corn stover (CS) has been considered an economical and available lignocellulosic biomass for producing high-value products, including bioethanol, it essentially needs pretreatment conditions to break down its structure and enhance cellulose accessibility for enzymatic saccharification and, high bioethanol production
On the basis of the SEM images, we found that the combined effect of autoclave and oxalic acid was more efficient in disrupting the lignocellulose cell wall, removing lignin, increasing the accessibility of cellulose, and improving the enzymatic saccharification as well

Summary

Introduction

According to the UN sustainable development goals and the challenges of the energy shortage, the utilization of agricultural perspectives as renewable energy resources is a target for a sustainable economy [1]. For a more green economy, renewable biomass such as crop residues are increasingly being utilized to produce chemicals, fuels, and energy; this transition to a more sustainable economy is a fundamental problem for society nowadays. Environmental issues such as price hikes of petrol-based resources and climatic change and the limited nature of oil supplies are the driving force that is causing the shift from a fossil-based to a bio-based economy. The primary source of lignocellulosic materials is in crops such as palm tree [4], sugarcane [5], wheat straw [6], rice husk [7], and corn stover [8]. Pretreatment is the most challenging step for improving the accessibility to subsequent hydrolysis and fermentation [11,12]

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