Efficient Degradation of Sulfamethoxazole via Reactive Oxygen Species Produced from Activated Peroxymonosulfate by MgCoFe-LDO Catalyst

Abstract

MgCoFe layered double oxides (MgCoFe-LDO) were fabricated to activate peroxymonosulfate (PMS) for degradation of sulfamethoxazole (SMX), and the highly efficient degradation of SMX revealed an excellent catalytic activity of Mg₂Co₁Fe₁-LDO for PMS under different pH values and water matrix. Scanning electron microscope analysis indicated the catalyst has a typical “flower-like” structure, and the X-ray powder diffraction analyses proved that the main crystal phase of Mg₂Co₁Fe₁-LDO is CoFe₂O₄ and Mg_1−xFe_xO, which is responsible for the good catalytic activity of Mg₂Co₁Fe₁-LDO. The radical scavenging experiments confirmed that ¹O₂, \({\text{SO}}_{4}^{\cdot - }\), OH and \({\text{O}}_{2}^{\cdot - }\) were involved in the degradation of SMX, but ¹O₂ and \({\text{SO}}_{4}^{\cdot - }\) played the dominant roles. According to the X-ray photoelectron spectroscopy (XPS) of Mg₂Co₁Fe₁-LDO catalyst, it was referred that the species including CoOH⁺, CoO⁺, Fe³⁺, FeOH²⁺, Fe²⁺, etc. involve in the activation process of PMS. Moreover, the possible degradation pathways of SMX were proposed according to the detected intermediates including N-hydroxy sulfamethoxazole, 3-amino-5-methylisoxazole from LC–MS analysis, and the toxicity analysis via Toxicity Estimation Software Tool software shows that most of the degradation products of SMX have lower toxicity than SMX.

Graphical Abstract