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).
