ZnFe2O4 substituted with Cu atoms for ultra-efficient formation of sulfate radicals: Extremely low catalyst dosage for thiamethoxam degradation

• Published in: Applied materials today Vol. 40; p. 102390
• Main Authors: Gao, Yuan, Li, Lian-Peng, Gong, Si-Yan, Huang, Jia-Hui, Xiang, Shuo, He, Gan, Wang, Qiong-Yu, Hu, Mian, Wang, Junliang, Pan, Zhiyan, Hu, Zhong-Ting
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2024
• Subjects: Spinel structure; Sulfate radical; Super/sub-critical fluid; Thiamethoxam; Thiamethoxam; Sulfate radical; Spinel structure; Super/sub-critical fluid
• ISSN: 2352-9407
• DOI: 10.1016/j.apmt.2024.102390

•Cu0.75Zn0.25Fe2O4 spinel structure prepared in subcritical fluid has 2 nm particle size.•Cu0.75Zn0.25Fe2O4/PMS system for thiamethoxam degradation is > 99 % in 40 min.•The driving force for PMS activation is from co-conversion Cu(Ⅰ)/Cu(Ⅱ) & Fe(Ⅱ)/Fe(Ⅲ).•EPR spectra combining with probe molecules is used for determining radical species.•Multi-metal coupling in polyhedron structure is a good way for enhancing the activity. Neonicotinoids as one of the newest major class of insecticides is a kind of persistent pollutants. Herein, copper-substituted zinc ferrites (Cu0.75Zn0.25Fe2O4) prepared in subcritical aqueous solution has a nanosize of ∼2 nm with high crystallinity and strong magnetic property. At low catalyst dosage of 0.05 g L−1, peroxymonosulfate (PMS) can be effectively converted into sulfate radicals in Cu0.75Zn0.25Fe2O4/PMS system. Thiamethoxam (THIA) degradation rate is in the order of Cu0.75Zn0.25Fe2O4 > CuFe2O4 > ZnFe2O4 (124, 84, 21 × 10−3 min−1, respectively). At pH ∼7.0, THIA degradation efficiency can be over 99 % in 40 min. The radical species (e.g., HO•, SO4•− and 1O2) were demonstrated by EPR spectra using probe molecules. The majority effects in Cu0.75Zn0.25Fe2O4/PMS system with kinetics modelling were comprehensively investigated as well. This work provides that multi-metal coupling, i.e., Cu(Ⅰ)/Cu(Ⅱ) & Fe(Ⅱ)/Fe(Ⅲ), in spinel structure by polyhedral design is an effective strategy for enhancing the catalytic activity. The Cu0.75Zn0.25Fe2O4/PMS system has promising for water treatment of neonicotinoid insecticide with ease of recycling catalysts by magnetic separation. [Display omitted]