A novel electrolytic-manganese-residues-and-serpentine-based composite(S-EMR) for enhanced Cd(Ⅱ) and Pb(Ⅱ) adsorption in aquatic environment

作者：Meng-Yu Ma; Xuan Ke; Yan-Chang Liu; Zhi-Hao Ha; Ting Wang; Jia Li^*; Fan Zhang; Tian C.Zhang

来源：Rare Metals, 2023, 42(01): 346-358.

Electrolytic manganese residue(EMR) is the waste slag generated from the electrolysis manganese industry.As a promising exploitable adsorbent,EMR has become a hot research topic.However,EMR’s low adsorption capacity has limited its applications as an efficient adsorbent.In this study,the EMR was mixed with serpentine and calcined(at 800℃ for 2 h) to prepare a composite adsorbent(S-EMR) with its specific surface area of 11.998 m2·g-1(increased compared to the original EMR) and improved adsorption capacities for Cd2+(98.05 mg·g-1) and Pb2+(565.81 mg·g-1).Kinetic studies have shown that the pseudo-first-order kinetics(PSO)model could best describe the adsorption kinetics of S-EMR for Cd2+/Pb2+,implying that the chemisorption process is the rate-limiting step.The effects of different interfering ions on S-EMR’ s adsorption for Cd2+/Pb2+may be due to the difference in their electronegativity.Results of response surface methodology tests showed that pH had the highest influence on adsorption,and the removal efficiency of S-EMR reached 99.92% for Cd(Ⅱ) and 94.00%for Pb(Ⅱ).X-ray photoelectron spectroscopy(XPS) analyses revealed that chemical precipitation was the predominant mechanism for Cd2+/Pb2+ removal,and the adsorption mechanisms were associated with ion exchange and electrostatic attraction.The results showed that S-EMR could be used as an effective adsorbent for the removal of Cd(Ⅱ)/Pb(Ⅱ) from water bodies,rendering dual benefits of pollution control and resource recovery.