Heterogeneous Fenton degradation of persistent organic pollutants using natural chalcopyrite: effect of water matrix and catalytic mechanism.

Abstract

Natural chalcopyrite was evaluated as heterogeneous Fenton catalyst. Catalytic performance was evaluated considering different systems, catalyst dosage, H2O2 concentration, and reaction temperature, and increasing the parameters favors rhodamine B degradation. Effect of aqueous matrix was systematically examined, involving solution pH, anions, cations, dissolved organic matter, and initial pollutant concentration. The degradation performance is slightly influenced by these parameters. Rhodamine B removal is 96.5% within 120min, the rate constant ranges from 0.0086min-1 to 0.0415min-1 depending on temperature, and the activation energy is 79kJ/mol. Effective degradation of different persistent organic pollutants including methylene blue, malachite green, sodium butyl xanthate, tetracycline, and p-nitrophenol is verified by UV-vis spectra. Natural chalcopyrite was characterized by advanced techniques including scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Reactions between chalcopyrite and H2O2 cause copper leaching and iron oxidation. Quenching experiments and electron paramagnetic resonance reveal the dominant role of hydroxyl radical in catalytic process. The catalytic mechanism induced by surface iron and leached copper derived from chalcopyrite is proposed.