Choice of Suitable Economic Adsorbents for\nthe Reduction of Heavy Metal Pollution Load

Abstract

Heavy metals e.g., Hg, Cd, Cr, Pb, Zn, As and Ni etc are a major sources of pollutants which enter into the food chains and cause serious health impairments, carcinogenicity and mutagenesis. They have adverse effects on blood composition, lungs, energy level, kidneys, central nervous system, liver, and other vital organs of the body. Heavy metals can be successfully removed by easily available, eco-friendly and low-cost adsorbents which include the wastes/products of natural (chitin, silicate porous material, clay and zeolites, vermiculite, cyclodextrin, chitosan, starch and its derivatives, alginates, fly ash), agricultural (walnut shell, Turkish coffee, waste tea, black gram, neem bark, coconut shell, coconut husk, coal, oil palm shell, sugarcane bagasse, rice, wool, waste tea, peat moss, Turkish coffee, exhausted coffee, crop biomass, rice straw, rice hulls, rice husk, rice, soybean hull, papaya wood, peanut shell, peanut, citrus fruits, palm date pits, black gram, wool, cassava waste, carrot residues, banana and orange peels, sugar-beet pectin gels, black gram husk) and industrial (waste rubber tire, waste slurry, lignin, fly ash, red mud)) origin. The adsorption efficiency is affected by functional groups and particle/ pore size of the adsorbent, speed of agitation, biosorbent dose, initial concentration and molecular size of metal ions, temperature and pH.