Low cost adsorbents for cadmium removal from wastewater

Abstract

Contamination of water by toxic heavy metals through the discharge of industrial wastewater is a worldwide environmental problem. Heavy metals form complexes or "ligands" with organic compounds. These modified biological molecules lose their ability to function properly, and result in malfunction or death of the affected cells. Cadmium has many uses, including batteries, pigments, metal coatings, and plastics. Cadmium and several cadmium-containing compounds are known carcinogens and can induce many types of cancer. Long-term exposure to lower levels of cadmium in air, food, or water leads to kidney disease. Other long-term effects are lung damage and fragile bones. Awareness of these effects has led to introduction of more strict legislations to control water pollution. Among the various techniques available to remove metal ions from water, adsorption is found to be an effective method. Over the last few years number of investigations has been carried out to test natural low cost adsorbents for heavy metal ion removal (Wan Ngah and Hanafiah (2007).