Adsorption of mercury from the aquatic environment using a novel nano-gel of Descurainia Sophia plant stem

Abstract

Mercury is one of the environmental toxic pollutants required to be removed. Mercury can interfere with the vital functions of the cells by binding to the sulfhydryl groups in enzymes and proteins. The purpose of this study was to investigate the adsorption of mercury ions from aqueous solutions using a novel adsorbent prepared by the nano-gel of Descurainia Sophia plant stem. Adsorption of mercury was performed in a discontinuous system. Detection of the adsorbent structure before and after the adsorption process was performed by SEM, TEM and FTIR analysis. The optimal mercury adsorption conditions were determined as 0.6 g/100 ml of mercury solution, the contact time of 100 min, and pH of 8. Under such conditions, the adsorption efficiency of 87.3% was obtained. Three parameters including Morris-Weber, pseudo-first-order, and pseudo-second-order kinetics were investigated to understand the kinetics of the removal process. Langmuir, Freundlich, and Dubinin-Radushkevich isotherms were also used to calculate adsorption capacity. The results showed that the nano-gel of Descurainia stem has a high ability to remove mercuric ions from aqueous solutions at different concentrations. Moreover, the temperature increase has a positive effect on the removal efficiency. The thermodynamic investigations indicate that the adsorption of mercury on the nano-gel of Descurainia stem is spontaneous and endothermic.