Degradation of ciprofloxacin by magnetic CuS/MnFe2O4 catalysts efficiently activated peroxymonosulfate

Abstract

Background

Ciprofloxacin (CIP) is a broad-spectrum antibacterial agent. Its extensive use has led to high frequency detection in various water environments, resulting in environmental pollution. The peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) is a promising method for the removal of organic pollutants due to its low cost and high redox potential.

Methods

Magnetic CuS/MnFe₂O₄ composites were successfully prepared using hydrothermal and solvothermal methods. The catalysts were characterized by XRD, SEM, TEM and VSM, and the degradation efficiency and mechanism of CIP by CuS/MnFe₂O₄/PMS system were investigated.

Significant findings

The results demonstrated that the magnetic CuS/MnFe₂O₄ composites exhibited superior catalytic performance than pure CuS and pure MnFe₂O₄. Under optimized degradation conditions (CuS/MnFe₂O₄=15 mg/L, PMS=1 mM, CIP=20 mg/L, initial pH = 5.89, T = 25 ℃), 98.9 % of CIP was degraded within 60 min. Metal ions (Cu, Mn, Fe) on the catalysts surface played an important role in activating PMS, whereas low-sulfur species (S²⁻ and S_n²⁻) promoted the Cu(II)/Cu(I), Mn(III)/Mn(II) and Fe(III)/Fe(II) cycles to accelerate the generation of free radicals. Additionally, $S{O}_4^{•-}$ and 1O₂ were considered to be important reactive species in the CuS/MnFe₂O₄/PMS system. Finally, the magnetic CuS/MnFe₂O₄ composites exhibited excellent recyclability and universality.