Recent advances in pretreatment technologies for efficient hydrolysis of lignocellulosic biomass

To improve world energy security, lignocellulosic substrates are being used to generate inexpensive renewable biofuel. Pretreatment of these biomasses is pre-requisite to obtain fermentable sugar for production of ethanol. Crystallinity, degree of polymerization, particle size, and accessible surface area of biomass often limits decrystallization of cellulose and depolymerization of hemicellulose during pretreatment. Various pretreatment technologies employed to diverse biomasses, their mechanism of action, feasibility and practicability for production of bioethanol and other bio-based products has been compared in this article. Intelligent combinatorial pretreatment approaches such as microwave-acid-alkali, ultrasound-surfactant, supercritical carbon dioxide and hot water-acid have been applied to increase sugar yield from a wide variety of feedstocks such as sugarcane bagasse, sugarcane top, corn stover, and switchgrass. Biological pretreatment using white, brown and soft rot fungi are attractive in terms of being cost effective, low energy requiring, and eco-friendly. Emphasis to optimize integrated biorefining processes, delineate pretreatment chemistries and their impact on cellulosic biomass to obtain greater yield of fuels and co-products are the highlights of this article. (c) 2015 American Institute of Chemical Engineers Environ Prog, 35: 489-511, 2016