Cu2+/Cu+ cycle promoted PMS decomposition with the assistance of Mo for the degradation of organic pollutant

• Published in: Journal of hazardous materials Vol. 411; p. 125050
• Main Authors: Zhou, Xin, Luo, Haopeng, Sheng, Bo, Chen, Xingyu, Wang, Yihao, Chen, Quanyuan, Zhou, Juan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.06.2021
• Subjects: 2,4-DCP; 2,4-dichlorophenol; Co-catalytic effect; Cu2+/Cu+ cycle; Cu2+/PMS; free radicals; humic acids; molybdenum; oxidation; pollutants; Cu2+/Cu+ cycle; 2,4-DCP; Mo; Cu2+/PMS; Co-catalytic effect
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.125050

The limited production of Cu+ in the Cu2+/PMS processes constrained its large-scan application for the elimination of organic pollutants. In this study, molybdenum powder (Mo) was applied as the co-catalyst to improve the degradation of 2,4-dichlorophenol (2,4-DCP) in Cu2+/PMS system at pH 5.6. By the assistance of Mo, Cu2+ was rapidly reduced to Cu+ which exhibited super activity for the peroxymonosulfate (PMS) activation. Compared with Cu2+/PMS processes, the PMS decomposition rate and 2,4-DCP degradation efficiency respectively increased by 62.1% and 83.6% in the Mo co-catalytic Cu2+/PMS system after reaction for 20 min. The degradation of 2,4-DCP was completed via both the free radical and non-radical pathways and the free radicals rather than Cu3+ contributed most to the reaction. In contrast to fresh Mo, the ratio of Mo4+ increased and Mo6+ decreased in the used Mo powder, due to the oxidation of Mo0 by Cu2+ and/or ∙OH and the reduction of Mo6+ by O2∙−. Additionally, the coexistence of Cl- and humic acid with low concentrations showed little effects on the Mo/Cu2+/PMS system while HCO3− presented an obvious depression for 2,4-DCP degradation. During five cycling runs, all the degradation rates were higher than 92.8%, indicating the good stability of Mo/Cu2+/PMS system. [Display omitted] •Cu2+/Cu+ redox cycles were achieved in the presence of metal Mo.•PMS decomposition was enhanced significantly by adding Mo.•Mo showed better co-catalytic effect than other solid co-catalysts.•The free radicals rather than Cu3+ contributed most to the degradation.•Mo/Cu2+/PMS system was highly stable during cyclic runs.