Adsorption of Pb in Water by Fe/<scp>MnO_x</scp>‐Loaded Attapulgite‐Hydrochar Composites: Efficacy and Mechanism

ABSTRACT In order to develop an effective method to remove Pb(II) from water, researchers created a novel composite material (FMHCA) using hydrochloric acid‐activated attapulgite (HATP) and hydrochar (HC) loaded with Fe/Mn oxides. The adsorption capacities of three adsorbents were comparatively analyzed: HATP, an attapulgite‐hydrochar composite (HCA), and a Fe/Mn‐modified HCA (FMHCA). The microstructure, elemental composition, and pore characteristics were determined by SEM–EDX, XPS, XRD, FTIR, and BET analyses. The beneficial functional groups, including Fe‐Mn oxides, hydroxyl, and carboxyl groups, present in the adsorbent were highly conducive to Pb(II) removal. The adsorption test demonstrated that the ratio of HATP to HC in the preparation of FMHCA material at a ratio of 1:3 was optimal, and FMHCA had a higher adsorption capacity for Pb(II) ( Q m = 320.85 mg/g) than both HATP and HCA. The adsorption of Pb(II) by FMHCA followed a pseudo‐second‐order model, with the isothermal adsorption model exhibiting a strong correlation with the Langmuir model. This suggests that the adsorption process is monolayer chemisorption. The findings of this study offer technical support for the cost‐effective and efficient removal of heavy metals from water.