Cobalt-loaded carbon nanofibers as magnetic catalyst for tetracycline degradation through peroxydisulfate activation: Non-radical dominated mechanism

Cobalt/carbon nanofibers (Co/CNF) were prepared by electrostatic spinning of CoCl2 center dot 6H2O and polyacrylonitrile solution and subsequent calcination. The physicochemical properties of Co/CNF were examined by various characterizations. The characterization results show the presence of multivalent cobalt in Co/CNF, the increased oxygen-containing groups on CNF surface, the microporous structure of Co/CNF, and the strong magnetic property. Compared with CNF, Co/CNF demonstrates a superior catalytic activity in activating peroxodisulfate (PDS) for the degradation of tetracycline (TC). The degradation of 89.5 % TC was obtained within 60 min in the Co/CNF/PDS system. The effects of process parameters such as Co/CNF dosage, PDS dosage, TC concentration, pH value, temperature, and common anions are studied on the removal of TC in the catalytic system. Electron paramagnetic resonance (EPR), quenching experiments, and electrochemical analysis confirm that TC degradation in the Co/CNF/PDS system relies on the non-radical pathway dominated by 1O2 and electron transfer. Co/ CNF not only activates PDS to generate reactive species, but also acts as an electronic intermediator from TC to the activated PDS surface for reaction. This study provides novel insights into the synthesis of efficient PDS catalysts for wastewater treatment concerning antibiotics.