Engineered design of MnFe2O4-Zn/Co ZIFs@MIL-53(Fe) composite for arsenic-bearing wastewater remediation: Performance optimization and mechanism elucidation

Arsenic (As) contamination is a global problem that requires innovative remediation, this study successfully synthesized a novel MnFe 2 O 4 -Zn/Co ZIFs@MIL-53(Fe) (MFZM) using a solvent method to remove As(V) from contaminated water. The MFZM exhibited a rhomboidal dodecahedron structure with a high specific surface area of 158.93 m 2 /g, which contributed to its exceptional adsorption performance under both acidic and neutral pH conditions. Notably, the adsorption capacity for As(V) reached approximately 599.90 mg/g at an equilibrium concentration of 500 mg/L, surpassing the performance of several previously reported adsorbents. The kinetic modelling results indicated that the adsorption process followed a pseudo-second-order mechanism, suggesting chemisorption as the dominant process. However, the isotherm studies demonstrate favorable single-layer adsorption, with the Langmuir model providing the best fit for the experimental data. The X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) analysis revealed that the Fe/Mn/Co on the MFZM surface can hydrolyze and generate Fe/Mn/Co-OH groups under pH conditions ranging from 3 to 7, facilitating the formation of stable coordination complexes with As(V). Furthermore, the MFZM provided abundant positively charged adsorption sites that effectively attracted HAsO 4 2− via electrostatic interactions, leading to efficient As(V) removal. These findings underscore the potential of the MFZM as a promising adsorbent for the effective remediation of As-contaminated wastewater, supporting sustainable environmental management.