A Review on Organic Adsorbents for the Removal of Toxic Metals from Waste Water

Abstract

The contamination of water due to explosive population growth rate, industrial operations, various toxic components particularly trace metals are affecting on the flora and fauna including on the human well-being. Water is essential requirement for process, developmental activities and all the living being. Due to manmade activities, there is an instant necessity to find different techniques for the removal of toxins in wastewater. Industrial processed effluent contains like nickel, lead, chromium, zinc, arsenic, cadmium, selenium and uranium. So far, a various type efficient methods are available for the removal of heavily metals such as chemical precipitation, ion exchange, reverse osmosis, ultrafiltration, electrodialysis, nanofiltration, coagulation, flocculation, floatation, etc. However available methods have numerous disadvantages like more reagent requirement, random removal of metal ion, generation of toxic sludge etc. At present, treatment of water in the economical process is very important. So the various natural adsorbents were used for the treatment of water. Adsorption techniques being very simple, economical, successful and flexible has become the most ideal methods for removal of toxic metals from wastewater. In this paper reviewed on readily available about 98 published articles (1990-2020) various natural materials as adsorbents for removal of heavy metals from wastewater. It is evident from the review of articles that ion-exchange, adsorption and membrane filtration are the most frequently apprised for the removal of heavy metal in wastewater. As these industries disposes untreated or poorly treated waste water containing toxic metals to the water bodies which in turn affect the human health those who are consuming it causing serious carcinogenic health effects. This review paper presents an overview of different adsorption techniques of heavy metal treatment from several wastewater samples. All of the cited authors and articles give the adsorption kinetics adopting isotherm models. By comparing many research values presented by an earlier number of papers. We draw conclusions for two new adsorption methods first one is with biosorbent and second one with synthetic materials. In this paper an attempt is made to study the effort done by the various researchers those who have made an attempt to treat the toxic waste water by using natural adsorbents and the results are discussed.