Effective removal of chromium from aqueous solution by adsorption on powdered wool: In-silico studies of adsorption mechanism

Abstract

• Molecular docking gives mechanism of adsorption of Cr(VI) on powdered wool. • Adsorption of Cr(VI) on powdered takes place at low pH and desorption at high pH. • Most of Cr(VI) is adsorbed on powdered wool within 30 s. • The process of adsorption is spontaneous and exothermic. • The Langmuir adsorption capacity of powdered wool for Cr(VI) is 23 mg/g. Industrial wastewater contains a significant quantity of Chromium (VI) which is greatly mobile in water and soil. It is genotoxic, carcinogenic and accumulates in plant and animal bodies. Current work reports the chromium removal by adsorption on powdered wool. Wool was powdered mechanically to 90–120 mesh size. Powdered wool before and after chromium adsorption was characterized using FTIR, BET, EDX, XRD, TGA, and FE-SEM. Powdered wool (175 mg) removed 99.43% of Cr(VI) from the solution at pH 2.1 on shaking for 3.5 min at 20 °C. Observed Langmuir adsorption capacity on powdered wool for Cr(VI) was 23 mg at 20 °C. Used powdered wool was regenerated by washing with pH 12.6 buffer solutions and reused without much decrease in its adsorption capacity up to three cycles (91.0% removal). Cr(VI) binding mechanism with powdered wool protein was studied using molecular docking and observed predominant interacting forces were hydrogen bonding and Van-der-Waals forces revealed.