Removal of Heavy Metal Cadmium from Industrial Wastewater Using Chitosan Coated Coconut Charcoal

Of the various toxic heavy metals discharged into the environment, cadmium is highly toxic and has a serious health concern. Removal of metals from industrial wastewaters has conventionally been accomplished by precipitation, ion exchange and electrolytic technology. More recently, adsorption using commercial activated carbon and carbon from different plant materials is in force. Use of activated carbon is quite expensive. Hence, the use of carbon from natural biopolymers has attracted attention of industrialists. Recently, surface modified carbon has generated diversity with far superior adsorption capacity. Among the various low cost adsorbents identified, chitosan has the highest adsorption capacity for several metals. But chitosan is slightly soluble at low pH, soft and has a tendency to agglomerate or form a gel in aqueous solutions, which makes the active binding sites of chitosan not readily available for sorption. Hence, providing a physical support will increase the accessibility of the metal binding sites. In the present investigation an attempt has been made to overcome these mass transfer limitations by synthesizing a biosorbent by coating chitosan on the surface of coconut shell charcoal. The chitosan coated charcoal showed higher efficiency of adsorption of cadmium than the pure charcoal.