A novel electrolytic‐manganese‐residues‐and‐serpentine‐based composite (S‐EMR) for enhanced Cd(II) and Pb(II) adsorption in aquatic environment
Mengyu Ma, Xuan Ke, Yan-Chang Liu, Zhihao Ha, Ting Wang, Jia Li, Fan Zhang, Tian C. Zhang
Abstract
Abstract 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 °C for 2 h) to prepare a composite adsorbent (S‐EMR) with its specific surface area of 11.998 m 2 ·g −1 (increased compared to the original EMR) and improved adsorption capacities for Cd 2+ (98.05 mg·g −1 ) and Pb 2+ (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 Cd 2+ /Pb 2+ , implying that the chemisorption process is the rate‐limiting step. The effects of different interfering ions on S‐EMR’s adsorption for Cd 2+ /Pb 2+ 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 Cd 2+ /Pb 2+ 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.