Peroxydisulfate activation by enhanced catalytic activity of CoFe2O4 anchored on activated carbon: A new sulfate radical-based oxidation study on the Cefixime degradation

Abstract

This work focused mainly on anchoring cobalt ferrite (CF) nanoparticles onto the surfaces of activated carbon (AC) for preparation of recoverable AC@CF composite as a heterogeneous peroxydisulfate (PDS) activator towards cefixime (CEF) degradation. Catalytic-mediated PDS activation potential of CF nanoparticles was significantly enhanced after anchoring onto the AC surfaces, indicating the efficient role of AC in inhibition of CF agglomeration. AC@CF/PDS system could achieve the complete degradation of CEF (with the reaction rate constant of 0.11 min−1) and 63.7% mineralization within only 40 min in the presence of 0.4 g/L catalyst and 3.0 mM PDS at pH 7.0. Comparative tests verified a strong synergistic effect (with synergy factor value of 2.75) between AC@CF and PDS towards CEF decontamination. The possible mechanisms of PDS activation, the generation of reactive species and the degradation pathway were proposed and discussed in details. AC@CF showed an excellent recyclability and stability in terms of CEF and TOC elimination and the removal efficiencies of 82.4 and 46.7% were attained in the fifth cycle, respectively. The quantity of leached metal ions from the catalyst surface to the reaction solution in each studied cycle was approximately < 2 % mass of used AC@CF. Based on the reactive species capture tests, the importance of their contribution in degradation process was in order of: SO4•– > HO• > O2•−. This work provides the key role of AC in improving the CF catalytic activity for activating PDS and efficient degradation of antibiotics from contaminated-water resources with high performance and safe application.