Degradation of methotrexate by unactivated and solar-activated peroxymonosulfate in water: Moiety-specific reaction kinetics and transformation product-associated risks

Shengqi Zhang; Yuwei Xie; Kyriakos Manoli; Yuefei Ji; Xin Yu; Mingbao Feng

doi:10.1016/j.watres.2023.120741

Degradation of methotrexate by unactivated and solar-activated peroxymonosulfate in water: Moiety-specific reaction kinetics and transformation product-associated risks

Water Res. 2023 Nov 1:246:120741. doi: 10.1016/j.watres.2023.120741. Epub 2023 Oct 14.

Authors

Shengqi Zhang¹, Yuwei Xie¹, Kyriakos Manoli², Yuefei Ji³, Xin Yu¹, Mingbao Feng⁴

Affiliations

¹ Fujian Key Laboratory of Coastal Pollution Prevention and Control, College of the Environment & Ecology, Xiamen University, Xiamen 361102, China.
² EnviroMuse Consulting, Ontario, Canada.
³ College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
⁴ Fujian Key Laboratory of Coastal Pollution Prevention and Control, College of the Environment & Ecology, Xiamen University, Xiamen 361102, China. Electronic address: mfeng24@xmu.edu.cn.

PMID: 37864882
DOI: 10.1016/j.watres.2023.120741

Abstract

Anticancer drugs have raised worldwide concern owing to their ubiquitous occurrence and ecological risks, necessitating the development of efficient removal strategies in water and wastewater treatment. Although peroxymonosulfate (PMS) is known to be a promising chemical in water decontamination, limited information is available regarding the removal efficiency of anticancer drugs by PMS and solar/PMS systems. This study first reports the moiety-specific reaction kinetics and mechanisms of methotrexate (MTX), an anticancer drug with widespread attention, by PMS (unactivated) and solar-activated PMS in water. It was found that MTX abatement by the direct PMS oxidation followed second-order kinetics, and the pH-dependent rate constants increased from 0.4 M^-1 s^-1 (pH 5.0) to 1.3 M^-1 s^-1 (pH 8.0), with a slight decrease to 1.1 M^-1 s^-1 at pH 9.0. The presence of chloride and bromide exerted no obvious influence on the removal of MTX by PMS. Furthermore, the chemical reactivity of MTX and its seven substructures with different reactive species was evaluated, and the degradation contributions of the reactive species involved were quantitatively analyzed in the solar/PMS system. The product analysis suggested similar reaction pathways of MTX by PMS and solar/PMS systems. The persistence, bioaccumulation, and toxicity of the transformation products were investigated, indicating treatment-driven risks. Notably, MTX can be removed efficiently from both municipal and hospital wastewater effluents by the solar/PMS system, suggesting its great potential in wastewater treatment applications. Overall, this study systematically evaluated the elimination of MTX by the unactivated PMS and solar/PMS treatment processes in water. The obtained findings may have implications for the mechanistic understanding and development of PMS-based processes for the degradation of such micropollutants in wastewater.

Keywords: Anticancer drugs; Degradation kinetics; Peroxymonosulfate; Secondary risks; Solar light; Wastewater treatment.

MeSH terms

Antineoplastic Agents*
Kinetics
Methotrexate / analysis
Oxidation-Reduction
Peroxides / chemistry
Wastewater
Water / analysis
Water Pollutants, Chemical* / chemistry

Substances

peroxymonosulfate
Methotrexate
Water
Wastewater
Peroxides
Antineoplastic Agents
Water Pollutants, Chemical