Natural bornite as an efficient and cost-effective persulfate activator for degradation of tetracycline: Performance and mechanism

Natural bornite (NBo), a kind of Fe-Cu bimetallic sulfide mineral, was selected as an efficient activator for persulfate (PS) to degrade a typical antibiotic, tetracycline (TC). The removal percentage of TC got up to 81.6% in 180 min in the NBo/PS system with a mineralization efficiency of 48.7%. Experiment results showed that the released Fe had played a more important role than Cu in the degradation process. Reductive sulfur in the NBo catalyst could enhance the regeneration of Fe2+ and thus improve the degradation efficiency of TC by activated PS. The results of radical-quenching and electron paramagnetic resonance tests demonstrated that the dominant reactive oxygen species responsible for TC degradation were center dot OH, SO4 center dot- and O-2(center dot-) in the NBo/PS system. The generated O-2(center dot-) was originated from dissolved oxygen rather than PS, but PS could accelerate the reduction process of O-2 to O-2(center dot-) by NBo. NBo dosage, PS concentration, initial solution pH and common inorganic anions (Cl- and H2PO4-) all had significant effects on TC removal. NBo was considerable stable in catalyzing PS for TC degradation. This work demonstrates an efficient and cost-effective catalyst towards PS for organic pollutant removal and provides new insight into the mechanism of heterogeneous activation of PS by Fe-Cu bimetallic sulfide.