Peroxymonosulfate activation by immobilized CoFe2O4 network for the degradation of sulfamethoxazole

Abstract

Heterogeneous activation of peroxymonosulfate (PMS) has been frequently proposed for the degradation of organic pollutants via the generation of reactive oxygen species (ROS). Spinel ferrite such as CoFe2O4 shows great advantage for PMS activation but suffers from aggregation problem and lack of microstructure. Herein, network-like CoFe2O4 immobilized on volcanic rock was synthesized for PMS activation for degrading sulfamethoxazole (SMX). The immobilized CoFe2O4 network exhibited good catalytic performance for SMX removal. Systematic investigations, including in situ ATR-FTIR and Raman spectroscopy analysis, chemical quenching experiments and electron paramagnetic resonance (EPR) tests, revealed that a redox cycle of Co2+/Co3+ induced the generation of ROS (SO4•−, OH• and 1O2) that participated in the degradation of SMX. Background constituents (e.g., inorganic ions and natural organic matters) exhibited limited influence on SMX removal. A continuous flow-through reaction in a fixed-bed column revealed the immobilized CoFe2O4 network could efficient degrade SMX with long-term durability, which therefore can be a promising catalyst for PMS activation for the degradation of SMX.