Preparation of a novel clay loaded with Fe (VI) for degradation of cefazolin: performance, pathway, and mechanism

Abstract

Cephalosporin antibiotics, a group of widely prescribed antibiotics, are frequently detected in wastewater effluent and in the natural aquatic environment. Materials have been sought to effectively degrade the antibiotics. In this study, a novel high-iron clay was prepared with potassium ferrate and montmorillonite via a strong alkaline in situ synthesis method. Degradation of cefazolin sodium (CFZ) by this novel Fe (VI)-clay was investigated. The optimal conditions for the degradation of CFZ were determined using a single factor experiment and response surface optimization method. We found that 89.84% removal efficiency was obtained in 137 min when pH value was 5.16 and Fe (VI)-clay dosage was 0.79 g. The CFZ degradation mechanism was studied by computations on the Frontier Electron Density (FED) in combination with spectroscopic and mass spectroscopic analysis. The spectroscopic characteristics of the products at different stages showed that the oxidation decomposition reaction occurred during the degradation of CFZ by Fe (VI)-clay. Furthermore, FED calculation combined with GC-MS results showed that the degradation pathways of CFZ by the Fe (VI)-clay was mainly the cleavage of β-lactam, thiadiazole, tetrazole, and dihydrothiazine rings.

Keywords: Cefazolin sodium; Degradation; FED; Fe (VI)-clay; Mechanism.