Removal of Ni, Cd, Pb, Zn and colour from aqueous solution using potential low cost adsorbent

Abstract

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A study was conducted to determine the removal efficiency of heavy metals (Ni, Cd, Pb and Zn) and colour from wastewater using cheap available materials in Malaysia such as charcoal, coconut shell carbon and a mixture of these carbons with limestone. As activated carbon is quite expensive, this study attempts to investigate the possibility of mixing activated carbon with these materials for cost saving. The suitability of using coconut shell after heating at 500°C in treating wastewater also formed the basis of the study. Batch studies were carried out in the laboratory with an initial concentration of heavy metals generally found in final effluents at 2 mg/L and colour at 400-ptCo. The results indicated that a mixture of activated carbon and limestone had removed 92% of heavy metals and 85% of colour from synthetic wastewater at a wide range of <i>p</i>H. When activated carbon was only used, 85% of heavy metals and 99% of colour were removed. For a mixture of charcoal with limestone, the removal efficiencies for heavy metals and colour were at 65% and 35%, respectively. The removal efficiency for heavy metals was further improved to 80% when charcoal was used, but for colour removal it was only 30%. The results of the study suggested that a mixture of activated carbon with limestone had significantly removed the amount of heavy metals and colour. Thus, the cost of the overall process can be reduced. This study also indicated that there is possibility of using coconut carbon and charcoal as an alternative absorbents for removing heavy metals and colour from wastewater. However, improvement on activation process is required.

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