Study On Treament Of Chromium And Vanadium Complexes Wastewater By Natural Iron-based Minerals/peroxymonosulfate

The heavy metals in modern industrial wastewater often cooperate with organics to form heavy metal complexes,which are more stable than free heavy metal ions and are difficult to precipitate and degrade.Various wastewater treatment technologies have been developed,among which advanced oxidation processes based on sulfate radicals are promising methods.This paper used Cr(Ⅲ)-citrate a and V(Ⅳ)-citrate complexes as model pollutants to explore the feasibility study of natural iron-based ore to activate peroxymonosulfate(PMS)advanced oxidation technology to degrade model pollutants.The effects of initial pollutant concentration,initial PMS concentration,pyrite addition amount,and coexisting ions on the degradation of vanadium and chromium-citrate complexes in the pyrite/PMS-alkali precipitation system were investigated.The activation of peroxymonosulfate in the reaction system and the degradation mechanism of pollutants were studied.In this study,firstly,four natural iron-based ores siderite,pyrite,magnetite and pyrrhotite were selected to activate PMS to remove Cr(Ⅲ)-citrate complexes.Pyrite was an excellent catalyst and had the best efficiency in degrading Cr(Ⅲ)-citrate complexes.The results showed that when the initial concentration of Cr(Ⅲ)-citrate complexes was 0.6 m M,the initial concentration of PMS was 5 m M and the dosage of pyrite was 4 g/L,the removal rate of total chromium was 97.1 ± 1.26%,and the degradation rate of TOC was 68.1 ± 1.37%.Four natural iron-based ores,siderite,pyrite,magnetite and pyrrhotite,were used to activate PMS to degrade V(Ⅳ)-citrate complexes Pyrite was the best reaction material and could degrade V(Ⅳ)-citrate complexes efficiently.PMS activated by pyrite was used to remove V(Ⅳ)-citrate complexes.The results showed that when the initial concentration of V(Ⅳ)-citrate complexes was 0.4 m M,the initial concentration of PMS was 5 m M and the dosage of pyrite was 8 g/L,the removal rate of total vanadium was 99.4 ± 0.87%,and the degradation rate of TOC was 73.9 ± 1.74%.The free radical quenching experiment proved that hydroxyl and sulfate radical played a common role in the degradation of heavy metal complex system by pyrite/PMS,and sulfate radical played a leading role.The analysis of ultraviolet and infrared spectra showed that the degradation of heavy metal complexes of vanadium and chromium mainly acted on the O-H bond of carboxylic acid.Pyrite could effectively activate PMS to produce strong oxidizing substances,thus breaking the complexes between heavy metals and organic ligands,reducing the released heavy metals by iron and further mineralizing the organic ligands.Metal ions in the reaction solution were eliminated by alkali precipitation.Pyrite had been recycled.After five times of utilization,pyrite still had high efficiency and stable catalytic performance.Through the exploration and research in this article,we can expand our thinking on the treatment of heavy metal complexes in natural and industrial wastewater,and provide a strategic method for the decontamination of chromium and vanadium co-contaminated site wastewater.