Efficient Removal of As from Industrial Wastewater by Nanocomposite MnFe₂O₄@Fe-UiO-67

Arsenic is a highly toxic element, and excessive levels can affect human health. Composites possess a larger specific surface area and better adsorption performance than single-MOF materials. In this paper, a simple novel nanocomposite (MnFe₂O₄@Fe-UiO-67) was synthesized by the one-pot method for the removal of arsenic from industrial wastewater. The synthesis and adsorption mechanism of the adsorbent were analyzed by a series of characterizations. The results showed that the adsorption behavior of MnFe₂O₄@Fe-UiO-67 was consistent with the pseudo-secondary kinetics and Langmuir isotherm model, i.e., it is a monomolecular layer chemisorption. Characterization by Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) showed that the active site formed a strong coordination bond (As-O bond) with As ions to achieve efficient adsorption. At 298 K and pH = 10, the arsenic removal rate can reach 98.43%, and the adsorption capacity is 600.25 mg/g, which is more than most of the existing reported adsorbents. Through thermodynamic analysis, it is found that the adsorption of As ions by the adsorbent is a spontaneous exothermic process. It can exhibit excellent adsorption performance at room temperature without the need for additional energy consumption. This adsorbent has great development prospects in the treatment of wastewater.