Department of Environmental Science, G.B. Pant University of Agriculture and Technology, Pantnagar (U.S. Nagar), Uttarakhand, India

 This review discusses the potential use of agricultural waste based bio-sorbents for sequestering heavy metals and synthetic dyes in terms of their adsorption capacities, cost effectiveness, binding mechanisms, operating factors and pre-treatment methods. Agricultural wastes are known to be rich in functional carboxyl and hydroxyl groups which facilitate binding of cation on to the surface. Adsorption by using low cost alternative adsorbent is a fascinating area as it has dual benefits i.e. water treatment and waste management. The literature survey indicates that agricultural waste based bio-sorbents have shown equal or even greater adsorption capacities compared to conventional adsorbents. In most cases, chemical pre-treatments bring about an obvious improvement in metal uptake capacity. However, there are still several gaps, which require further investigation, such as (i) searching for novel, multi-function agricultural waste based bio-sorbents, (ii) developing cost-effective modification methods and (iii) assessing agricultural waste based bio-sorbents under multi-metal and real wastewater systems. Once these challenges are addressed, the replacement of traditional adsorbents by agricultural waste based bio-sorbents in decontaminating heavy metals and dyes from wastewater more efficiently could be achieved.

Keywords:Adsorption capacities; Agricultural wastes; Bio-sorbents; Heavy metals; Synthetic dyes.