Enhanced photodegradation of sulfadimidine via PAA/g-C3N4-Fe0 polymeric catalysts under visible light

The sever antibiotics pollution in water environment has been a worldwide concern. In this research, a poly acrylic acid (PAA)/graphitic C3N4 (g-C3N4) matrix loaded with zero valent iron (Fe-0) was synthesized. The PAA/g-C3N4-Fe-0 was confirmed to be an efficient photocatalyst for the degradation of sulfadimidine (SM2) under visible light. The dosage of g-C3N4 and Fe-0 were optimized in line with photocatalytic performance. The as-prepared samples were comprehensively characterized through chemical structure, morphology, electrochemical and optical measurements. The photodegradation kinetics under different conditions (e.g. pollutant concentration, pH values, various ionic species and common organic component) were studied. The enhanced photocatalytic activity was due to the improved electron transfer efficiency by the evenly dispersed Fe-0 in PAA/g-C3N4 network. The photodegradation of SM2 was confirmed to be driven by center dot O-2(-) and center dot OH radicals originating from the active components induced by visible light. Based on the above experimental analysis, a possible photodegradation mechanism of PAA/g-C3N4-Fe-0 photocatalyst was thoroughly elucidated. Besides, the degradation intermediates of sulfadimidine were analyzed by liquid chromatography - mass spectrometer (LC-MS), and possible degradation pathways were proposed in coordination with the calculated results based on Density Functional Theory (DFT). Thus, this study revealed the great prospect of the as-prepared PAA/g-C3N4-Fe-0 photocatalyst in wastewater remediation.