REMOVAL OF CADMIUM IONS FROM WATER / WASTE WATER USING CHITOSAN - A REVIEW

Abstract

The removal of Cd2+ions from wastewaters is gaining wide interest from both environmental and economic viewpoints due to its serious hazardous impact on humans, animals and plants. Various adsorbents have been used viz., activated carbons, plant or lignocellulosic wastes, clay, biopolymers etc. Chitosan, a crustacean waste has gained wide attention as an effective biosorbent due to its low cost and high contents of amino and hydroxyl functional groups. Chemical modifications leading to the formation of chitosan derivatives, grafting chitosan and chitosan composites are extensively studied and widely reported in the literatures. The aim of this review is to summarize the sorption efficiencies of chitosan and its derivatives in the removal of Cd2+ ions from electroplating effluents and synthetic waters. A comparison on the chitosan derivatives prepared by five different methods as reported by researchers (thiocarbonyl, PVA blend, xanthate, Nano based and grafting) and an outline of their potential applications in the adsorption of Cd2+ ions are dealt in this paper. Amongst the mentioned composites reported, chitosan grafted with γ- cyclodextrin is found to possess better chelating ability in sequestering Cd2+ ions.