Environmental Remediation of Sulfamethazine Wastewaters by Iron Doped Perylene Diimide Supramolecular Catalysts in a Visible Light Driven Photocatalytic Process: Optimization and Kinetic Approach

Abstract The presence of pharmaceutical compounds in water sources threaten the environmental and human health due to their complex molecular structures and persistence. The release of improperly treated pharmaceutical wastewaters into aquatic medium may result in development of drug-resistant microorganisms and endocrine disruption. Sulfamethazine, as a type of sulfonamides is one of the most widely used agents particularly in veterinary medicine. Therefore, the effective removal of sulfamethazine from water is of importance. The main focus of the study is to search for an environmental solution for the removal of recalcitrant organic compounds by testing the performance of iron impregnated perylene diimide supramolecular photocatalysts (Fe/PDI) in photo Fenton-like oxidation of sulfamethazine. The interactive effects of the operating parameters were examined in the presence of Fe/PDI by using Box-Behnken Design. The optimum photo Fenton-like reaction conditions were determined as 0.45 g/L catalyst dosage, pH 3 and 6.46 mM H 2 O 2 dosage. The low iron leaching (1.344 ppm) detected in the treated sulfamethazine solution indicates the stability of the catalyst and its suitability for practical applications. The kinetic studies revealed that fitting is consistent with 1st and 2nd order kinetics but literature suggests that 2nd order is likely to be correct for the sulfamethazine degradation. The activation energy was determined as 11.3 kJ/mol in the presence of Fe/PDI photocatalyst. The radical quenching tests showed that the dominant reactive species is the hydroxyl radicals. The photocatalytic activity of the Fe/PDI was tested for the removal of different pollutants under the same reaction conditions. Complete Procion Red MX-5B decolorization was achieved in 15 min and 71.2% oxytetracycline hydrochloride degradation was obtained in 120 min. Optimization studies and modeling of reaction kinetics are significant for the application of environmentally friendly and effective supramolecular catalysts and industrial wastewater treatment systems. Graphical Abstract