Crystal violet degradation in the ozone/persulfate/ferroferric oxide system: A heterogeneous catalytic process for simultaneous catalysis of ozone and persulfate

Crystal violet (CV) is a widely used cationic triphenylmethane dye, mostly from textile, leather and other industrial manufacturing companies. The carcinogenicity, teratogenicity and mutagenicity of crystalline violet have received widespread attention, but due to the toxicity of crystalline violet itself, the It is difficult to degrade crystal violet by conventional wastewater biological treatment system. In this study, Fe3O4 was used to activate ozone and persulfate to degrade crystal violet in water. The results showed that the degradation of crystal violet followed a pseudo-second-order kinetic model and logistic model in the O3/PDS/Fe3O4 system, there was an obvious synergistic effect among ozone, persulfate, and Fe3O4. The effect of chelating agents and background components in aqueous solution on the degradation of crystalline violet in the O3/PDS/Fe3O4 system was investigated. The Radical quenching experiments and electron spin resonance spectra show that the generation of SO4•-, •OH, and 1O2 is the main cause of crystal violet degradation. After eight reuses of ferroferric oxide, the catalytic activity of Fe3O4 slightly decreased, but it still showed a high removal effect on crystal violet. The catalysis of Fe3O4 in O3/PDS/Fe3O4 system is mainly carried out by heterogeneous catalytic process, including electron transfer in Fe(Ⅱ)/Fe(Ⅲ) redox and lattice oxygen, catalytic ozonation process of surface hydroxyl groups. The O3/PDS/Fe3O4 system has an EE/O of 139.23 kWh·m−3 per order, indicating a higher energy efficiency compared to the other process. Intermediate products of CV degradation were identified by ultraviolet absorption spectrometry and liquid chromatography-mass spectrometry (LC-MS), and the degradation pathways of CV were determined.