CRITICAL REVIEW ON ADSORPTION OF HEAVY METAL IONS FROM INDUSTRIAL WASTEWATER

Abstract

Industrialization, urbanization and overpopulation have created many problems such as heavy metal ions contaminated water and the need of clean water is the utmost need in this modern era. Removal of these inorganic pollutants such as copper (Cu⁺²), lead (Pb⁺²), chromium (Cr⁺³, Cr⁺⁶) cadmium (Cd⁺²), zinc (Zn⁺²) and mercury (Hg⁺²) ions from wastewater is necessary because they are usually carcinogenic, mutagenic and non-biodegradable in nature. Therefore, its removal is necessary to decontaminate industrial, surface as well as ground water from these hazardous pollutants. Different methods such flotation, coagulation-flocculation, reverse osmosis, photocatalytic method, chemical precipitation, ion-exchange, membrane separation, advanced oxidation and adsorption are some of the techniques for remediation of wastewater. Each method has some pros and cons, like precipitation produce sludge problem and its treatment is needed after this method. Membrane separation, reverse osmosis and advanced oxidation methods are effective but they are expensive. Fouling, scaling and periodic cleaning of membrane are some of the disadvantages of membrane separation process. Photocatalytic and electrical methods are not so mature methods. Adsorption is although a slow process but its cost-effective, eco-friendly, high specific surface area, porous structure, higher uptake, multifunctional groups and ease regeneration like properties make it a best method for removal of heavy metal ions from synthetic and industrial wastewater. In this paper adsorption, its types, adsorbents and its types, factors effecting adsorption process, adsorption kinetics, adsorption equilibrium and adsorption isotherms have been discussed.