Synergistic Integration of Fenton Oxidation and ZIF-8 Adsorption: A Novel Strategy for Dual Arsenic Species Removal in Wastewater

The removal of both organic and inorganic arsenic is crucial for safeguarding the environment and human health, which constitutes a key aspect of sustainable development. In this study, a novel method integrating Fenton oxidation with ZIF-8 adsorption was developed for the simultaneous treatment of roxarsone (ROX) and arsenite (As(III)) from wastewater. ZIF-8 was hydrothermally synthesized and characterized using X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Elemental Mapping (EM), Brunauer–Emmett–Teller (BET) surface area analysis, and zeta potential analysis. Comprehensive characterization demonstrated that the synthesized ZIF-8 exhibited a well-defined rhombic dodecahedral morphology with smooth crystal surfaces and an exceptionally high specific surface area of 1836.23 m²/g. Under the optimized conditions for Fenton oxidation (4.90 mmol/L H₂O₂, 0.1380 g/L FeSO₄·7H₂O, pH 3, 30 min) and ZIF-8 adsorption (0.1 g/L ZIF-8, pH 6, 180 min, 25℃), the integrated system exhibited remarkable removal efficiencies of 92.32% for ROX (20 mg/L) and 95.16% for As(III) (1 mg/L). Specifically, compared to the individual processes, the removal efficiency of ROX was increased by 20.59% (versus Fenton-only) and 52.63% (versus ZIF-8-only), while that of As(III) was enhanced by 29.17% and 35.51%, respectively. Additionally, the integrated system exhibited maximum adsorption capacities of 107.76 mg/g for ROX and 17.70 mg/g for As(III), further confirming the presence of synergistic effects between Fenton oxidation and ZIF-8 adsorption. The adsorption processes for ROX and As(III) followed pseudo-second-order kinetics and were best described by the Langmuir adsorption model, suggesting chemisorption and monolayer adsorption on a homogeneous surface. The removal mechanism in the synergistic method involved three primary pathways: oxidation reactions (•OH), electrostatic interactions (-OH/-NH₂), and precipitation (FeAsO₄). This study demonstrates that the proposed synergistic method (Fenton@ZIF-8) is a promising technology for the simultaneous removal of both organic and inorganic arsenic species from contaminated water, with strong potential for practical application in wastewater remediation.