Adsorption of Pb(II) and Cd(II) by magnetic activated carbon and its mechanism

• Published in: The Science of the total environment Vol. 757; p. 143910
• Main Authors: Zhang, Zhen, Wang, Tao, Zhang, Huixue, Liu, Yonghong, Xing, Baoshan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 25.02.2021
• Subjects: Activated carbon; adsorbents; Adsorption; aqueous solutions; coprecipitation; electrostatic interactions; endothermy; environment; Heavy metals; hot water treatment; kinetics; magnetism; Manganese ferrite; sorption isotherms; straw; thermodynamics; Manganese ferrite; Adsorption; Activated carbon; Heavy metals
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.143910

Magnetized activated carbons (MAC) were prepared by activating rape straw powder, and pyrolyzing at different temperatures, then magnetizing activated carbon by hydrothermal method. MAC-300 had the largest adsorption capacity of Pb(II) (253.2 mg/g) and Cd(II) (73.3 mg/g). The adsorption isotherms and kinetics could conform to the Freundlich model and pseudo-second-order kinetic model, respectively, indicating that the adsorptive behavior of the adsorbent mainly depends on the non-uniform active points on the surface of the material. Meanwhile, the thermodynamic parameters showed that the adsorption of Pb(II) and Cd(II) by MAC-300 was a spontaneous and endothermic reaction. The adsorption capacity of MAC-300 could be improved by properly increasing the pH of the original solution. There was competitive adsorption when high-valent ions were present in solution. In combination with various characterizations and comparison tests of samples after adsorption, the adsorption mechanisms include surface electrostatic attraction, surface complexation, and co-precipitation. The results indicated that the MAC material was a potential material to remove heavy metal ions from the aqueous solution. [Display omitted] •Activation carbon embedded with MnFe2O4 magnetic particles (MAC-T) was fabricated.•MAC-T had excellent ferromagnetic properties, stability, and reusability.•MAC-T showed high adsorption ability for Pb(II) and Cd(II).•The mechanisms were electrostatic attraction, complexation, and co-precipitation.