A review of sugarcane bagasse pretreatment for bioethanol production

Abstract

Bioethanol is a new and renewable energy source. The second-generation bioethanol production process from lignocellulosic materials has development opportunities. This is because the first generation of bioethanol raw materials is generally a food source. Diversification of raw materials for the bioethanol production process can be developed through the use of non-food or waste sources. The process of developing bioethanol from local non-food resources or waste can increase energy security and the added value of these sources. One of the potential sources is sugarcane bagasse. The production process of bioethanol from sugarcane bagasse consists of: (i) pretreatment; (ii) enzymatic hydrolysis; (iii) fermentation; (iv) distillation; and (v) dehydration. The major composition of sugarcane bagasse consists of cellulose, hemicellulose, and lignin. Sugarcane bagasse requires a pretreatment process to separate lignin and hemicellulose from cellulose, reduce the crystallinity of cellulose and facilitate the hydrolysis of cellulose. This review focuses on sugarcane bagasse pretreatment for bioethanol production. There are several types of pretreatment processes, including (i) physical pretreatment; (ii) acid pretreatment; (iii) alkaline pretreatment; (iv) organosolv pretreatment; (v) steam explosion; and (vi) wet oxidation. Physical pretreatment is the process of physically changing the size of the sugarcane bagasse to be smaller. Chemical pretreatment is the separation process of lignin and hemicellulose from cellulose using acid compounds. Alkaline pretreatment is the separation process of lignin and hemicellulose from cellulose using alkali compounds. Organosolv pretreatment is lignocellulosic pretreatment using organic solvents. Steam explosion is the process of disrupting the complicated structure of sugarcane bagasse using steam. Wet oxidation is the process of biomass treatment with water, oxygen, or air. Steam explosion is superior to other processes in terms of hemicellulose solubilization, reaction time and no toxic substances.