Hexavalent chromium adsorption from aqueous solution utilizing activated carbon developed from Rumex abyssinicus

The indiscriminate release of chromium-saturated effluent into water bodies has raised concerns regarding its effect on human health and environmental ecology. Therefore, this research aimed to remove hexavalent chromium from an aqueous solution utilizing activated carbon developed from Rumex abyssinicus. The adsorbent was prepared through chemical impregnation with H3PO4 and then thermally activated at 500 for 2 h. The optimization of the adsorption experiments was performed using the Box‒Behnken approach of response surface methodology. The characterization of the prepared activated carbon revealed good quality in terms of its amorphous structure, maximum specific surface area of 1722.9 m2/g and porous surface. Furthermore, the optimization results showed that a maximum removal efficiency of 95.97% was attained at an optimum working pH of 3, a contact time of 60 min, an initial chromium concentration of 70 mg/L and an adsorbent dosage of 0.6 mg/100 mL. The Langmuir isotherm model was found to have the best fit with the experimental data. Moreover, the kinetics study revealed that a pseudo-second-order model fit the data best, indicating the occurrence of chemisorption. Overall, this study suggested that Rumex abyssinicus could be an effective adsorbent for removing hexavalent chromium from aqueous solutions.