Mn–Ce oxide-modified activated carbon composites as efficient adsorbents for removing As(iii) from water: adsorption performance and mechanisms

Abstract

The efficient removal of toxic heavy metal As(III) from water environments has become increasingly urgent due to its adverse health effects. In this study, Mn–Ce oxide-modified activated carbon (Mn–Ce/AC_x) composites were synthesized using a simple hydrothermal process and investigated for their As(III) adsorption performance. The Mn–Ce/AC₃ composites exhibited exceptional adsorption properties, with high oxidation and adsorption capacity for As(III), owing to their high specific surface area (213.45 m² g⁻¹) and the presence of surface hydroxyl groups with high affinity. At pH = 7.0, the adsorption capacity of Mn–Ce/AC₃ composites for As(III) reached 73.16 mg g⁻¹. Even at very low equilibrium As(III) concentrations, Mn–Ce/AC₃ composites could further reduce the concentration to less than 10 μg L⁻¹ at an initial As(III) concentration of 10 mg L⁻¹, which meets WHO standards. Moreover, over a wide pH range of 2–9, Mn–Ce/AC₃ composites effectively removed As(III) by oxidation followed by adsorption, indicating that this material is a highly promising adsorbent for the treatment of As(III)-contaminated water.