Enhanced Removal of As(III) and Ciprofloxacin from Wastewater Using ZIF-67 Coupled with Fenton Reaction: Mechanisms and Techniques

Abstract

The efficient and effective removal of mixed pollutants from wastewater is of paramount importance for environmental remediation, given the diverse nature of contaminants present. In particular, arsenic (As) and ciprofloxacin (CIP) contamination in surface water has become increasingly severe. To address this challenge, this study synthesizes ZIF-67 and integrates it with the Fenton reaction to remove mixed As(III) and CIP pollutants from wastewater. Comprehensive characterization of ZIF-67 was conducted using FTIR, XRD, SEM, and BET analyses, as well as pHpzc measurements. As an efficient adsorbent, ZIF-67 offers a high surface area (1614 m²/g) and excels in removing pharmaceutical contaminants. A systematic investigation was conducted to evaluate the influence of key reaction parameters-including pH, H2O2/Fe2+ ratio, reaction temperature, adsorbent dosage, and reaction time-on pollutant removal efficiency, ultimately determining the optimal reaction conditions. The removal of As(III) and CIP follows a pseudo-second-order kinetic model and fits the Langmuir isotherm. Experimental results demonstrated that the maximum removal efficiencies for As(III) and CIP reached 98.07% and 99.96%, respectively, when ZIF-67 was coupled with the Fenton reaction. Mechanism studies indicate that during the coupling process, the Fenton reaction generates highly reactive hydroxyl radicals (•OH). These hydroxyl radicals (•OH) can oxidize trivalent arsenic and CIP into pentavalent arsenic and intermediate products, which are more easily adsorbed by ZIF-67, thereby enhancing the adsorption efficiency of ZIF-67 for pollutants. By leveraging the synergy of ZIF-67 and the Fenton reaction, this study proposes a promising strategy for enhanced As(III) and CIP removal, offering novel methods for wastewater treatment.