Energy efficient process for valorization of corn cob as a source for nanocrystalline cellulose and hemicellulose production

Int J Biol Macromol. 2020 Jul 2;163:260-269. doi: 10.1016/j.ijbiomac.2020.06.276. Online ahead of print.

Abstract

Synthesis of nanoparticle from biopolymers present in agricultural waste residue is significant as they are eco-friendly and serve as alternative to unrenewable petroleum resources. This research focuses on utilizing Corn cob, a lignocellulosic biomass for the simultaneous production of cellulose and hemicellulose using an energy efficient method. A sequential process of microwave irradiation and ultrasound technique is carried out to obtain cellulose and hemicellulose at a faster rate. Microwave assisted delignification showed that delignification of about 97.31% was achieved at an optimum condition of 180 W power, 12.86% Sodium chlorite and 16 min reaction time. Ultrasound assisted alkali extraction resulted in a yield of 0.445 g of cellulose /g of corn cob and 0.327 g of hemicellulose /g of corn cob at an optimum condition of 41 °C, 14% NaOH for 46 min. The extracted cellulose and hemicellulose were converted into nanoparticles as they show unique properties in nanoscale size. Acid hydrolysis was found to reduce the average particle size of cellulose from 894 nm to 131.4 nm and alkylation and nanoprecipitation was shown to decrease the size of hemicellulose from 876.9 nm to 130.4 nm. Nano Cellulose structure with a crystallinity index of 72.36% was retained which increases their applications as reinforcement material in polymer matrices.

Keywords: Corn cob; Delignification; Nanocellulose; Nanohemicellulose; Ultrasound.