Peroxymonosulfate activation by Co-doped magnetic Mn3O4 for degradation of oxytetracycline in water.

Liyan He,Xiaoli Li,Hui Li,Jianzhi Wang,Qifei Gao

doi:10.1007/s11356-022-18929-1

Abstract

Co-doped magnetic Mn3O4 was synthesized by the solvothermal method and adopted as an effective catalyst for the degradation of oxytetracycline (OTC) in water. Synergistic interactions between Co-Mn3O4 and Fe3O4 not only resulted in the enhanced catalytic activity through the activation of peroxymonosulfate (PMS) to degrade OTC but also made Fe3O4/Co-Mn3O4 easy to be separated and recovered from aqueous solution. 94.2% of OTC could be degraded within 60min at an initial OTC concentration of 10mg L-1, catalyst dosage of 0.2g L-1, and PMS concentration of 10mM. The high efficiency of OTC removal was achieved in a wider pH range of 3.0-10.0. Co (II), Co (III), Fe (II), Fe (III), Mn (II), Mn (III), and Mn (IV) on Fe3O4/Co-Mn3O4 were identified as catalytic sites based on XPS analysis. The free radical quenching experiments showed that O2•- radicals and 1O2 played the main role in the degradation process and the catalytic degradation of OTC involved both free radical and non-free radical reactions. Eventually, the intermediates of OTC degradation were examined, and the possible decomposition pathways were proposed. The excellent catalytic performances of Fe3O4/Co-Mn3O4 came from the fact that the large specific surface area could provide abundant active sites for the activation of PMS and the redistribution of inter-atomic charges accelerated the redox reactions of metal ions. The high degradation efficiency and rate constant of OTC in actual water samples indicated that Fe3O4/Co-Mn3O4 had a good practical application potential.

Highlights

With people’s increasing attention to environmental sustainability and public health, pharmaceutical and personal care products (PPCPs) are widely used in medicines for preventing and treating human and animal diseases and as personal care in daily life (Zhang et al 2015; Hutchings et al 2019), resulting in a large amount of wastewater containing PPCPs and their metabolites being discharged into the environment
The SEM results showed that the surfaces of Fe3O4 and Fe3O4/Co-Mn3O4 were rough, and Fe3O4 was closely bonded with Co-Mn3O4
The ultimate results revealed that the catalytic activity was significantly inhibited after furfuryl alcohol (FFA) was added, which indicated that 1O2 was another reactive species that contributed to the high efficiency of OTC degradation. These results demonstrated that radicals and nonradicals were all involved in the degradation process of OTC, where O2− and 1O2 played a major role in the catalytic reaction

Summary

Introduction

With people’s increasing attention to environmental sustainability and public health, pharmaceutical and personal care products (PPCPs) are widely used in medicines for preventing and treating human and animal diseases and as personal care in daily life (Zhang et al 2015; Hutchings et al 2019), resulting in a large amount of wastewater containing PPCPs and their metabolites being discharged into the environment. The catalytic activity was investigated by adding 0.2 g L−1 catalyst and 10 mM PMS into 100 mL, 10 mg L −1 OTC solution at its natural pH value, and the reaction lasted for 60 min.

Results

Conclusion