Synthesis and characterization of cellulose from locally available rice straw

Abstract

Rice is the main agricultural food in Sri Lanka today. Paddy crops are cultivated as a wetland crop in all the districts. Rice straw is a waste product of the rice harvest that is generated in equal or greater quantities than the rice itself.Despite these larger quantities, rice straw is frequently burned in open air by farmers which makes it a significant source of pollution. In the search for possible uses of rice straw, it was found that rice straw contains considerable amount of cellulose which pave the way for the production of cellulose. This study mainly focuses on the synthesis and characterization of cellulose from rice straws of most frequently used traditional (Suwandel, Raththal) and technically modified (BG300, BG352) rice varieties in Sri Lanka. Up to date, pure cellulose has been separately isolated from rice straws of above mentioned four rice varieties after following a three-step de-waxing, delignification and hemicellulose (and silica) removal process. The formation of pure cellulose and complete removal of non-cellulosic materials from rice straw was confirmed by FTIR spectroscopy after each chemical purification step. Highest cellulose yield was observed from rice straws of Suwandel variety (35.2%). Other rice varieties showed cellulose yield BG352 (29.3%), BG300 (27.9%) and Raththal (25.1%).