Modification and management of lignocellulosic waste as an ecofriendly biosorbent for the application of heavy metal ions sorption

Abstract

The aim of this study is more towards environmental friendly solutions by transforming the lignocellulosic waste into valuable material which improves and upgrades technology for waste management and minimization. Therefore, the recent advances are based on improvements in the removal of hazardous materials by efficient and low-cost bio-sorbents. Agricultural waste contains a high concentration of cellulose which is a low cost, biodegradable, non-toxic, thermally and mechanically stable which explores the study towards clean and sustainable development. Different types of biomass are taken as adsorbent like leaves, fibers, husk, stem, seeds etc. The present study emphasis a clean and sustainable treatment for the elimination of metal ions from the environment by the management of waste i.e. sugarcane bagasse, rice husk, coconut husk etc. Various adsorption parameters have been examined at optimized conditions such as temperature, the dosage of adsorbent, contact/agitation time, pH, flow rate, bed height and concentration of dye or metal ions. Spectrophotometric techniques are used for the evaluation of the concentration of metal ions before and after sorption. This review summarizes many modifying agents and grafting techniques for the elimination of metal ions which improves the adsorption capacity. The present study compiles the grafting on the backbone of cellulose. This review recapitulates the different routes of extraction and modification of cellulose. The properties of biosorbent will be enhanced by several modification techniques but out of all these grafting is considered as the most effective one is shown in this study. This review also summarizes the various grafting methods with free radical grafting mechanism. This review also compiles the studies based on modified and unmodified biosorbents for the comparison of sorption capacities with and without modification. The chemically modified cellulosic biomass is mostly preferred than unmodified one due to more adsorption efficiency favored by a maximum number of reactive binding sites, enhanced ion-exchange properties and availability of more functional groups after modification.