REMOVAL OF TOXIC METAL IONS FROM WASTEWATER USING POLYMERIC GELS

Abstract

Due to rapid industrialization, it has been brought ever increasing compounds in waste streams, both as rejected products of industrial processes and as residues of common commercial products. This has resulted in the degradation of quality of receiving bodies of water and land and thereby impairing their beneficial use. The chromium and cadmium are also found in the waste water. There are various methods available for the removal of chromium and cadmium from waste water. Methods used are reduction, ion-exchange, evaporative recovery, adsorption on activated carbon, fly ash, hard coke dust etc. Adsorption is an efficient and widely used technique for the treatment and recovery of metal ions from the waste water. Polymeric gels has currently created an interest among the various workers to use it as an adsorbent for various metal ions. In this dissertation, an effort has been made to study the adsorption behaviour of Cr(VI) and Cd (II) ions on polyacrylamide gels. Experimental data are collected at different initial metal ion concentration, pH variation, contact time variation and result are suitably interpreted. A decreasing trend in present uptake amount of metal ions on increasing the initial concentration of metal ions at fixed temperature has been observed. On increasing the pH of medium, the uptake amount of the metal ion by the polymeric gels has shown increasing trend. There was more uptake of metal ions on increasing the pH, which clearly indicated that polymeric gels can efficiently be used in alkaline media. Studies of contact time variation show that the adsorption is more at initial stage when gradually decreases and remain almost constant after certain optimum time. The experimental data have been fitted well in Freundlich isotherm and the values of constants (k1) and lin for metal ions concentration has been calculated. On comparing the adsorption data for Cr(VI) and Cd(II) metal ions, it has been observed that percentage removal of Cr(VI) is more than that of Cd(II) under same experimental conditions such as initial metal ion concentrations, pH and contact time so it is observed that polyacrylamide gels are relatively more efficient adsorbent for the Cr(VI) metal ions than the Cd (II) from the aqueous phase.