"Value added products from waste biomass and its application"

Abstract

Rice husk is a prime agricultural derivative of rice cultivation in countries such as India where rice is cultivated and consumed as a staple food. In the current hunt for renewable resources for energy generation and production of products with high market value in a cost-efficient manner, rice husk seems to be a major contender. Starting from biofuel to the production of value-added products alike activated carbon and flavouring 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. In order to disintegrate the structure of lignocellulose followed by extraction of these compounds, different pretreatment methods have been utilised. Initially the literature survey emphasises the constituents of rice husk along with different pretreatment methods to reduce lignocellulosic biomass as a mean to extract cellulose, lignin and hemicellulose. Moreover, the synthesis of cellulose, lignin, hemicellulose, silica and phytochemicals and their usage in manufacturing of profuse value-added products such as bioethanol, biofuels, vanillin, xylitol, xylan, furfural etc. has also been addressed. In the first part of the research, effect of ultrasonication assisted acid-alkaline pretreatment on rice husk has been studied to obtain effective removal of cellulose, lignin and hemicellulose. Alongside that, synthesis of microcrystalline cellulose and silica nanoparticle has also been performed. Besides that bioethanol synthesis using Sacchromyces cerevisiae along with furfural has been done from rice husk derived cellulose. In the later part of the study, alkaline treated rice husk derived cellulose was used to remove wastewater pollutant malachite green from an aqueous solution. Effect of different parameters along with contact time were observed such as adsorbent dose, MG concentration, initial pH of the solution and process temperature. The isotherm, kinetics and thermodynamic parameters were calculated. 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.