Efficient removal of lead ion from aqueous solution by β-Cyclodextrin modified magnetic sludge biochar

To address the contamination of water bodies by heavy metal, beta-cyclodextrin modified magnetic sludge biochar (beta-CD@MBC) was synthesized from urban sludge via a chemical co-precipitation method for removing Pb2+ from aqueous solution. The structural and morphological characteristics of the material were analyzed using various characterization techniques, and the adsorption performance for Pb2+ was evaluated through single-factor experiments. Results indicated an increase in the number of surface functional groups in beta-CD@MBC compared to the original sludge biochar (BC) and magnetic sludge biochar (MBC). Both pseudo-second-order and Langmuir models effectively described the removal process. The actual maximum adsorption capacity of beta-CD@MBC at 298 K reached 444.96 mg/g, significantly higher than that of the BC (71.82 mg/g) and MBC (172.32 mg/g). Thermodynamic suggested that the removal reactions were a spontaneous endothermic process. The removal of Pb2+ by beta-CD@MBC was influenced by the combined effects of complexation, electrostatic interactions, cation-pi interactions, and co-precipitation. After five desorption cycles, the Pb2+ removal capacity of beta-CD@MBC for 100 mg/L Pb2+ decreased by 17.29%, which was lower than that of BC (71.53%) and MBC (39.80%). These results suggested that beta-CD@MBC held significant potential for removing Pb2+.