Studies on value added products from agro residue based biorefinery waste lignin by using photocatalytic process

Abstract

Sustainable development calls for proper management and optimum utilization of agricultural wastes. The current practice of large-scale stubble burning goes against this notion. It is seriously detrimental to the environment and causes underutilization of precious renewable resources. One of the options to manage this waste could be the production of second- generation bioethanol wherein the carbohydrate fraction of lignocelluloses is hydrolyzed and subsequently fermented to ethanol. Typically, about half the starting material, most of it being lignin, ends up as solid residue after bioethanol production. Rice straw is biomass as a crop s residue having main contents as cellulose hemicellulose and lignin. Rice straw is first required depolymerization to produce further liquid fuels or value-added chemicals. As per biorefinery prospects, cellulose and hemicellulose can be used directly but lignin is left as waste with limited industrial use. Lignin is an aromatic, highly irregular, and insoluble polymer consisting of phenylpropanoid subunits. Effective use of waste lignin is always a challenging task, technologies have been applied in the past to get value-added compounds from waste lignin. However, the existing technologies are not economical and efficient to produce value-added chemicals. Lignin valorization is a key issue for an economically viable lignocellulosic biorefinery and can be a crucial cog in the circular economy. Alleviation of the global energy crisis may be possible from the conversion of lignin to value-added chemicals because of its presence in lignocellulosic biomass as the second most abundant component. Photocatalysis is one of the multifarious advanced oxidation processes (AOPs), that generates highly reactive hydroxyl radicals and other strong oxidants, which shows the capabilities to produce value- added compounds from waste lignin. newline