Removal of heavy metals from wastewater using modified agricultural adsorbents

Abstract

Agricultural waste has been investigated as an efficient adsorbent for heavy metal removal because of their low cost. The functional groups present in agricultural wastes such as carbonyl, phenolic, acetamido, alcoholic, amido, amino and sulphydryl group etc. have an affinity for heavy metal ions to form metal complexes or chelates. The removal of heavy metal ions from wastewater using agricultural waste is based upon metal biosorption. The mechanism of biosorption includes chemisorption, complexation, adsorption on the surface, diffusion through pores and ion exchange etc. These heavy metal ions cause life-threatening problems for the humans and aquatic ecosystem. Certain modifications in these adsorbents enhance the adsorption capacity of these adsorbents. Some chemicals such as mineral and organic acids, bases, oxidising agent are used for modification of adsorbents. The purpose of this article is to compare removal efficiency of different adsorbents.