Removal of heavy metal ions from aqueous system by ion-exchange and biosorption methods

Pollution due to heavy metals is currently a serious problems affecting water bodies. The removal of heavy metals is of great concern due to their toxicity at trace levels and accumulation in the biosystem. Here we review the technical feasibility of biosorption and ion exchange methods for the removal of various heavy metals from the aqueous media. Chemical pretreatment of low-cost biosorbents are presented. Chemically modified biosorbents exhibit far better adsorption capacities than unmodified ones. We also highlighted the effect of pH on the biosorption for maximal uptake of heavy metals, because pH modifies the surface charge of the biosorbent as well as the speciation of heavy metals.