From Farm to Fuel

Rice husk is a major agricultural by-product of rice cultivation in countries like China and India, where rice is cultivated and consumed as a staple food. In the current hunt for renewable resources for energy generation and the production of value-added products in a cost-efficient manner, rice husk seems to be a major contender. Starting from biofuel to the production of activated carbon and flavoring agents, rice husk can play an important role as lignocellulosic biomass. As a source of nature’s most dominant biopolymer, rice husk constitutes cellulose, lignin, and hemicellulose as the major building blocks, along with silica and phytochemicals. To break down the structure of lignocellulose and extract these compounds, different pretreatment methods including physical, chemical, and biological, have been utilized. This review emphasizes the constituents of rice husk, along with different pretreatment methods to reduce lignocellulosic biomass to extract cellulose, lignin, and hemicellulose. Moreover, the synthesis of cellulose, lignin, hemicellulose, silica, and phytochemicals and their usage in the production of various value-added products such as bioethanol, biofuels, vanillin, xylitol, xylan, furfural, etc., has also been addressed. In other words, the journey of rice husk from being a landfilling agricultural waste to the synthesis of numerous value-added products has been studied in this chapter.