International Journal of Scientific and Research Publications, Volume 10, Issue 7, July 2020 801 ISSN 2250-3153 This publication is licensed under Creative Commons Attribution CC BY. http://dx.doi.org/10.29322/IJSRP.10.07.2020.p10389 www.ijsrp.org Optimization of acetic acid pretreatment of corn stover for bioethanol production Lazarus K. Limo 1 , Dr. Stephen M. Talai 2 , Daniel K. Arusei 3 1,2,3 Department of Mechanical and Production Engineeing, Moi Univerity, Eldoret Kenya DOI: 10.29322/IJSRP.10.07.2020.p10389 http://dx.doi.org/10.29322/IJSRP.10.07.2020.p10389 Abstract- It has been found that different pretreatment of corn stover produces varying quantities of reducing sugars. Therefore, this study experimentally investigated the optimum conditions with respect to concentration of acetic acid, temperature and time. Response surface methodology (RSM) was employed for the analysis of the simultaneous effect of acid concentration, pretreatment temperature and time on the resulting total reducing sugar concentration obtained. A three-variable, five-level Central Composite Rotatable Design (CCRD) of experiment was used to develop a statistical model for the optimization of the process variables. The findings showed that the optimum total reducing sugar were acetic acid concentration; 91.89%, temperature; 150 ℃ and time; 5 hours. Under these conditions, the total reducing sugar concentration obtained was21.09/. Validation of the model indicated insignificant difference (±1.2) between predicted and observed values. This study found that corn stover has a potential of producing substantial amount of reducing sugars which are the major raw materials in the production of bioethanol. Index Terms- Acetic acid, Corn stover, Reducing sugars, bioethanol, Response surface methodology (RSM) I. INTRODUCTION Corn stover is lignocellulosic biomass that can be converted into fermentable sugars for the production of second generation biofuels such as cellulosic ethanol[1, 2]. The conversation process is facilitated by use of either enzymatic or chemical hydrolysis. Chemical pretreatment processes include the use of acids, alkalis, catalyzed steam-explosion, Ammonia fiber/freeze explosion (AFEX), pH-controlled liquid hot water, Ionic liquids (ILs) and organic solvents, among others[3]. Currently the world is faced with crisis of fossil fuel depletion and environmental degradation. Demirbas [4] indicated that the oil crisis and the continuous increase in oil prices have led countries to investigate new and renewable fuel alternatives. The major organic components of biomass are celluloses, hemicelluloses and lignin [1, 4-6]. There are three ways to use biomass. It can be burned to produce heat and electricity, changed to gas-like fuels such as methane, hydrogen and carbon monoxide or converted to a liquid fuel. Biofuels (liquid or gaseous fuels produced from biomass) are predominantly two forms of alcohol: ethanol and methanol. Biofuels generally offer many benefits including sustainability, reduction of greenhouse gas emissions, regional development, reduction of rural poverty and fuel security [4, 7]. The most commonly used biofuel is ethanol. This is generally produced from sugarcane, corn, and other grains. Gasoline and ethanol blends are already used in cities with high air pollution. However, ethanol made from biomass is currently more expensive than gasoline. Therefore, there is a need to find out the less expensive ways to produce ethanol from other biomass crops. Ethanol feedstocks are classified into three types: i. Sucrose-containing feedstocks. ii. Starchy materials. iii. Lignocellulosic biomass. Lignocellulosic biomass, such as agricultural residues (corn stover and wheat straw), wood and energy crops, is attractive materials for ethanol fuel production since it is the most abundant reproducible resource on Earth. Production of renewable biofuels can be classified based on the production technologies employed as illustrated in Table 1 Table 1: Classification of renewable biofuels based on their production technologies[4] Lignocellulose materials are broken down into individual sugars followed by fermentation to ethanol. The prerequisite in the utilization of lignocellulose for ethanol production is to efficiently yield fermentable hydrolyzates rich in glucose from the cellulose content present in the feedstock T Generation Feedstock Example First generation biofuels Sugar, starch, vegetable oils or animal fats Bioalcohols, vegetable oil, biodiesel, byosyngas, biogas Second generation biofuels Non-food crops, wheat straw, corn, wood, solid waste, energy crops Bioalcohols, bio-oil, bio-DMF, biohydrogen, bio- Fischer-Tropsch diesel, wood diesel. Third generation biofuels Algae Vegetable oil, biodiesel Fourth generation biofuels Vegetable oil, biodiesel Biogasoline