Hydrogen Sulfide Removal from Downstream Wastewater Using Calcium-Coated Wood Sawdust-Based Activated Carbon

Hydrogen sulfide is very toxic and dangerous. It can be observed in a huge amount in petroleum wastewater. In this study, residual wood sawdust was chemically modified by potassium hydroxide to produce wood sawdust activated carbon (ACWSD) and subsequently coated with calcium (Ca) extracted from eggshell. The Ca-coated ACWSD was applied in the sorption of dissolved H2S and its ions (HS− and S2−) from simulated wastewater. Response surface methodology was employed to investigate the impact of various variables such as calcination temperature, concentration of calcium solution, and calcination contact time on the responses. The result showed that the highest adsorption capacity and product of impregnated activated carbon (IAC) were obtained at the following optimum conditions: calcination temperature of 890.86 °C, calcium concentration in the solution of 49 v%, and impregnated contact time of 61.58 min for the preparation of Ca-ACWSD, resulting in the highest removal efficiency (RE%) and IAC yield % of 96.86% and 30.161%, respectively. X-ray powder diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopies were used to confirm the physicochemical properties of the Ca-ACWSD adsorbent. Modified activated carbon has higher RE % compared with unimpregnated one. Freundlich isotherm model is more fitted to adsorption capacity. The result IAC has shown the best performance for the removal of these priority water pollutants.