Sequestration of toxic Cr(VI) ions from industrial wastewater using waste biomass: A review

Heavy metal pollution is one of the most pressing environmental problems today. Several metals such as chromium, mercury, lead, copper, cadmium, zinc and nickel are considered as a highly toxic heavy metals. These metals are carcinogenic and pose a severe threat to the ecosystem and living organisms in it. Among various heavy metals, Cr(VI) is of particular interest because it is commonly found in the wastewater. Therefore, the removal of chromium is essential for environmental protection. Many conventional technologies have been developed for the removal of heavy metals from aqueous solutions such as membrane separation, ion exchange, filtration, precipitation, liquid-liquid extraction, solid-liquid extraction, reverse osmosis, etc. However, most of these are not economically feasible. Biosorption is a promising alternative biotechnological innovation for the removal of heavy metals from aqueous effluents. Biosorption method of wastewater treatment is highly competent and ecofriendly. A range of materials that act as biosorbent such as fungi, bacteria, algae, activated carbon, agro wastes, etc., have been used for the removal of heavy metals from aqueous solutions. The parameters influencing the removal of chromium, kinetics, mechanism, isotherms and thermodynamic study details were discussed in this article. This study encompasses an overview of past research and current development of the biosorption field for the effective removal of Cr(VI) ions from aqueous effluents.