REMOVAL OF HEAVY METALS FROM POLLUTED WATER BY DEALUMINATED KAOLINITE

Abstract

Heavy Metals pollutants affect the human health when their concentrations exceed the permissible limits. The dealuminated kaolinite is used as a cost effective adsorbent to remove heavy metals such as Mn, Zn, Ni, Cd contaminants from contaminated water. The dealiminated kaolin was characterized and compared to raw kaolin. The factors affecting the adsorption process, such as pH, time, and S/L ratio, were investigated by statistical design of experiments. The statistical design results indicated that the optimum manganese removal is about 64.5% at high pH and extraction time of 3 hours. In addition, a strong interaction was noticed between pH and solid-liquid ratio. The order of heavy metals removal was Mn > Cu > Zn > Cd. This order was attributed to the ionic radius of metals. Finally, the adsorption mechanism was elucidated in terms of dealuminated kaolinite structure and high surface area of DAK, ionic species of heavy metal as a function of pH. The higher removal at alkaline pH range was explained by precipitation of metals hydroxide.