Review on Heavy Metal Removal and Efficacy of Biosorbents

Abstract

Industries release a significant amount of wastewater contaminated with heavy metals. It is a major cause of pollution and a potential health hazard when discharged into the environment without treatment. Standard adsorbents for removing heavy metals have certain limitations, like incomplete metal removal, high energy requirements, and undesirable waste generation. Therefore, the use of biosorbents is an effective alternative to conventional procedures. This critical review evaluates and summarizes the optimum results obtained from different papers covering different parameters such as biosorbent removal efficiency and their adsorption capacity, adsorbent dosage, and effect of pretreatment for removal of single and combination of heavy metals. The influence of pH, contact time, and sorbent dose on biosorption has been discussed. The Langmuir model and the Freundlich model are studied for various biosorbents, and the respective results are obtained and summarised. The pseudo-first and second-order models have been evaluated to study the sorption kinetics. Through this review, it can be concluded that biosorbents can be a promising alternative to treat industrial effluents, mainly because of their high metal binding capacity, low cost, high efficiency in diluted effluents, and environmentally friendly nature.