Pak. J. Bot., 44(1): 169-176, 2012.
OPTIMIZATION OF DILUTE ACID PRETREATMENT USING RESPONSE SURFACE METHODOLOGY FOR BIOETHANOL PRODUCTION FROM CELLULOSIC BIOMASS OF RICE POLISH ZAHID ANWAR1, MUHAMMAD GULFRAZ1, MUHAMMAD IMRAN1, M. JAVAID ASAD1, AFTAB IQBAL SHAFI1, PERVEZ ANWAR1 AND RAHMATULLAH QURESHI2,* 2 1 Department of Biochemistry, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi Department of Botany, Pir Mehr Ali Shah Arid Agriculture University Rawalpindi, Pakistan.
Abstract Lignocellulosic biomass is abundant and a renewable resource for the production of biofuel (bioethanol) by using fermentative organisms (Sacchromyces cervesiae & Fusarium oxysporum). Rice polish is a cheaper agro-waste for bioethanol production. The conversion of biomass into maximum yield of glucose, an important step for the bioethanol production, requires optimum dilute acid treatment. Inhibitory compounds reduce the ethanol production; therefore an attempt has been made in the present study to select suitable dilution by using Response surface methodology (RSM) design and to minimize the effects of inhibitory compounds during sulphuric acid (H2SO4) dilution. The treatment of biomass with H2SO4 (1.5%) at 100°C for 30 minutes exhibited optimum results. During enzymatic hydrolysis 16.52 mg/mL glucose was obtained by using 1 mL of enzymatic load at 50oC after 72 hours of hydrolysis. The Glucose thereafter converted to 5.21g/L and 3.69 g/L of ethanol during fermentation process by using Sacchromyces cervesiae and Fusarium oxysporum respectively.
Introduction A variety of lignocellulosic materials like agricultural residues, municipal and industrial wastes are being investigated for bioethanol production (Ying et al., 2009). Cellulose is an abundant biopolymer on the earth and is considered the best renewable energy resource (Rezaei et al., 2008). The major limitations exist for the productions of ethanol from agricultural wastes due to physical and chemical associations between lignin and polysaccharides of plant cell wall along with cellulose crystallinity. Lignin forms a protective covering around cellulose and hemicellulose, which restrict the enzymatic degradation (Dawson & Boopathy, 2008). Cellulose is separated from lignin by dilute acid treatment and then glucose is recovered from cellulose by enzymatic hydrolysis. However, economical production of ethanol depends on efficient conversion of cellulose to its monomeric sugars (Takagi et al., 1977). Saccharification technologies are necessary to liberate fermentable sugar for ethanol production. Therefore, efficient pretreatment method is needed to increase the efficacy of enzymatic hydrolysis to obtain maximum glucose yield (Teng-Chieh et al., 2010). Rice polish is a by-product of rice milling and is the cheapest source of cellulose material available in bulk quantity in major rice growing areas of the Pakistan (Ambreen et al., 2006). The different strains of Thermoanaerobacter and Clostridium were used for the production of ethanol from different lignocellulosic biomass. However, Saccharomyces cerevisiae or Zymomonas mobilis has advantage on other strain due their efficiency for conversion of glucose into ethanol and also being ethanol tolerant (Sommer, et al., 2004). Rice polish has potential for the production of ethanol and there is no proper utilization of this agro-waste in Pakistan. The present study was conducted to select a better dilute acid treatment by using response surface methodology and also to determine the possibly designed factor which gives less loss of glucose, better solubilization of xylose and maximum degradation of lignin leading to a better recovery of glucose by enzymatic hydrolysis and ethanol production using Sacchromyces cervesiae (Badal et al., 2005). *Corresponding author e-mail: firstname.lastname@example.org
Materials and Methods Sample collection: All chemicals used during these researches were of analytical grade manufacture by Merck (Germany)....
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