The removal of heavy metal ions from aqueous effluents by modified clays: Retention of Cd(II) and Ni(II) ions

Industrial effluents discharged into aquatic bodies without proper treatment have contributed to the increasing pollution of water by heavy metals. The development of efficient processes for the treatment of industrial effluents is becoming more and more vital since legislation concerning the disposal of metal-contaminated effluents is becoming ever more rigorous. In the present work, the adsorption of Cd(II) and Ni(II) ions by chelate-impregnated clays has been examined. Montmorillonite K10, an acid-treated industrial clay purchased from Fluka Chemicals, was impregnated with di(2-ethylhexyl)phosphoric acid (D(2)EHPA), sodium diethyldithiocarbamate (DDTC) and the disodium salt of iminodiacetic acid (IDA). We have investigated the sorption process from both the static (batch) and kinetic viewpoint, and have studied the influence of pH and temperature on the process. It was observed that the clays exhibited rapid adsorption capabilities and that those impregnated with IDA and DDTC had a high efficiency in the removal of Cd(II) and Ni(II) ions.