Photo-Fenton degradation of sulfamethoxazole using MIL-53(Fe) under UVA LED irradiation and natural sunlight

Abstract

The MOF MIL-53(Fe) was synthesized, activated and evaluated in photo-Fenton reactions assisted by UVA LED irradiation and natural sunlight using the antibiotic sulfamethoxazole (SMX) as a degradation target molecule. A 23 full factorial design of experiments was carried out in order to determine the effects of several parameters' influence on the degradation of SMX. The effect of different operational parameters such as pH, hydrogen peroxide and catalyst concentration was analyzed, and tests of reuse of the catalyst were performed. Likewise, the dissolved organic carbon (DOC), iron leached from the MIL-53(Fe) structure and H2O2 consumption were monitored, and the degradation products of the reaction were identified. The use of MIL-53(Fe) as a heterogeneous photo-Fenton catalyst using natural sunlight as an irradiation source allowed the degradation of 96% of the SMX in solution in just 120 min under near-neutral conditions. Likewise, removal of 30% of the DOC in solution was achieved, being the leached iron concentration less than 0.20 mg L−1, a value within the quality standard of water intended for human consumption imposed by the European Union (Directive 98/83/CE). Efficiency and stability after multiple cycles postulate the MOF MIL-53(Fe) as a potential heterogeneous catalyst to be considered in the development of alternative water purification systems based on the photo-Fenton process. An appropriate combination of solid-state characterization and chemical analysis techniques were applied, including PXRD, DRS, ZP, SEM, FTIR, HPLC-DAD, HPLC-MS/MS, and UV-Vis, which provided the experimental evidence that supports this study.