Agro-based Adsorbents for Dye Removal from Aqueous Solutions: A Review

Dyes or coloring agents are discharged into the environment from numerous industries. These pollutants pose a serious threat to the ecosystem due to their inherent characteristics. New and innovative technologies have been emerging in the field of pollutant removal. However, most of these methods are energy intensive and demand high cost. Adsorption is assumed to be an easy and effective approach for pollutant removal. Apart from the conventional adsorbents, agricultural wastes have shown their ability to act as excellent adsorbents for pollutant removal from wastewaters. Owing to the large availability and the intrinsic adsorption characteristics, the farming byproducts such as leaf wastes, hull wastes, husk wastes, seeds, and bird feathers can substitute costly adsorbents. Physical or chemical modifications are usually incorporated into such adsorbents to alter their surface characteristics in order to enhance the adsorption capabilities. Modeling studies can be carried out to understand the relationship between the adsorbent and the dye molecule and to determine the dye removal capabilities of the adsorbents. This review incorporates the various reported studies on adsorptive removal of dyes using common, locally available agro-based adsorbents.