Reducing Sugar Production from Teff Straw Biomass Using Dilute Sulfuric Acid Hydrolysis: Characterization and Optimization Using Response Surface Methodology.

Andinet Alemayehu Tesfaw,Belachew Zegale Tizazu,Wen-Cheng Chen

doi:10.1155/2021/2857764

Andinet Alemayehu Tesfaw, Belachew Zegale Tizazu + Show 1 more

Open Access

https://doi.org/10.1155/2021/2857764

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Abstract

The present study evaluated first the characterization of Teff straw and then Box–Behnken design (BBD), and response surface methodology was adopted to optimize the parameters (hydrolysis temperature, dilute sulfuric acid concentration, solid to liquid ratio, and hydrolysis time) of dilute sulfuric acid hydrolysis of Teff straw in order to get a maximum yield of total reducing sugar (TRS). The chemical analysis of Teff straw revealed high amounts of cellulose (41.8 wt%), hemicellulose (38 wt%), and lignin (17 wt%). The morphological analysis using SEM showed that hydrolyzed Teff straw with dilute sulfuric acid has more pores and distorted bundles than those of raw Teff straw. XRD analysis also indicated that hydrolyzed Teff straw has higher crystallinity index and smaller crystallite size than raw Teff straw, which might be due to removal of hemicellulose, amorphous cellulose, and lignin components. Under the optimized conditions for dilute sulfuric acid hydrolysis of Teff straw (120°C, 4% v/v H2SO4 concentration, 1 : 20 solid to liquid ratio, and 55 min hydrolysis time), we have found a total reducing sugar yield of 26.65 mg/g. The results of validation experiment under the optimum conditions agreed well with model predictions.

Highlights

Biomass is by far the largest energy provider contributing a total of 1,150 million tons of oil equivalent which translates into a 79% share of the total energy supply [1]
Dame [2] reported that in Ethiopia an average of 3.7 million tons of Teff cereal has been produced per annum; correspondingly large amount of Teff straw has been produced during banging, which was more than 2 million tons of Teff straw in every year
Dilute sulfuric acid pretreatment could destroy the cellulose-hemicellulose-lignin structure, thereby removing some of the external fibers. us, the lignin and hemicellulose of the dilute H2SO4 acid pretreated Teff straw were partially removed and broken or became loose. e exposure of internal structures of Teff straw with acid increases the accessibility of cellulose for further processing [10]. e results of Scanning Electron Microscope (SEM) analysis (Figure 1(b)) indicated that acid hydrolysis of Teff straw showed significant surface modification, i.e., developed honeycomb-like rough surfaces, nonuniform pores, and cavities caused by the reaction between H2SO4 and ester bonds, which led to removal of lignin and hemicellulose with cellulose domination [7]

Summary

Introduction

Biomass is by far the largest energy provider contributing a total of 1,150 million tons of oil equivalent which translates into a 79% share of the total energy supply [1]. Because of the depletion of fossil fuels and environmental pollution, researchers have been committed to studying the production of value-added chemicals and biofuels originated from lignocellulosic biomass [1]. Lignocellulosic biomass is an abundant and inexpensive source of fermentable sugars for the production of biofuels and value-added chemicals. Teff straw is among the lignocellulosic materials used for the synthesis of biofuels and value-added products [2]. Dame [2] reported that in Ethiopia an average of 3.7 million tons of Teff cereal has been produced per annum; correspondingly large amount of Teff straw has been produced during banging, which was more than 2 million tons of Teff straw in every year It has been primarily disposed of through burning in the field, rather than used as animal feed. It has been primarily disposed of through burning in the field, rather than used as animal feed. e disposed of Teff straw could cause environmental pollution

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