This document discusses delignification, which is a pretreatment process for lignocellulosic biomass like rice straw to improve enzymatic hydrolysis for biofuel production. It explains that alkaline pretreatment using chemicals like sodium hydroxide is commonly used to degrade lignin and make cellulose more accessible. While calcium hydroxide is inexpensive, sodium hydroxide requires less water and lower temperatures. The document also notes that rice straw is a promising feedstock due to its abundance and reviews how pretreatment alters the lignocellulose structure to improve downstream processing into biofuels.