Application of Agricultural Wastes as a Low-cost Adsorbent for Removal of Heavy Metals and Dyes from Wastewater: A Review Study

Water chemical pollution originates from a wide range of toxic derivatives, especially heavy metals and dyes. Its destructive effects on humans and the ecosystem have been considered as a serious environmental disaster. Therefore, there is a need to develop technologies to remove toxic pollutants from the environment. Adsorption is one of the most common methods of removing contaminants from wastewater among all the proposed methods. Adsorption is an optional method for industrial sewage treatment and a useful instrument for environmental protection. In recent years, numerous studies have been conducted to achieve low-cost, efficient, and environmentally friendly adsorbents. Among the low-cost adsorbents, the application of agricultural waste, as bio-adsorbent, is the most widely used for removing heavy metals and dyes. The advantages of using these compounds are low cost, good efficiency, minimal energy, simple maintenance and high adsorption capacity. This study deals with the risks, effects, and resources of manufacturers of heavy metal and dyes in addition to examination of agricultural wastes as low-cost adsorbents. Moreover, equilibrium, kinetic, and thermodynamic behaviors of the process of adsorption of heavy metal ions and dyes, using Langmuir and Freundlich adsorption isotherms, and Pseudo first and second-order kinetic models, and thermodynamic parameters were studied.