Degradation of humic acid via peroxymonosulfate activation by FeCo2O4 nanoparticles supported on modified coal gangue

Industrial solid waste can be used as nanoparticles potential supports to form heterogeneous catalysts for removing organic substances. Herein, coal gangue was modified by sulfuric acid pickling and high-temperature calcination, and FeCo2O4/modified coal gangue (FC-MCG) catalysts were synthesized via a citric acid combustion method. The crystal structures, surface morphology and elemental valence of the synthesized composites were investigated. The 20% FC-MCG possessed higher catalytic performance for HA degradation than other composites, achieving almost 85% degradation efficiency of HA (20 mg/L) in the presence of PMS. The fluorescence EEMs and FTIR spectra revealed the effective destruction of HA structure after reaction in the 20% FC-MCG/PMS system. Electron paramagnetic resonance (EPR) tests and quenching experiments showed that the SO4 center dot-, (OH)-O-center dot and O-1(2) were produced in the PMS activation process. Additionally, the 20% FC-MCG catalyst still kept excellent catalytic performance after four times repeated use. This study was a meaningful exploration for conversion of industrial solid waste to high effective catalyst for wastewater treatment.