Environmental Sciences Proceedings (Mar 2023)
Comparative Analysis of Photodegradation of Ibuprofen and Clotrimazole Water Pollutant Using UVC Rays in Presence and Absence of ZnO Photocatalyst
Abstract
The recent surge in pharmaceutical micro-pollutants in water bodies calls for an efficient method to neutralize wastewater to sustain the ecosystem. One of the ways to degrade drug molecules is through photocatalytic degradation using UV rays. ZnO is known to be a common catalyst in the degradation of contaminants found in wastewater. However, due to its toxicity to the environment, there is a need to objectively re-evaluate its necessity and alternatives. In addition, most studies have focused on the utilization of UVA/UVB rays for the photocatalytic degradation process, as such, there are currently limited studies evaluating the efficacy of UVC for such purpose. In this work, we provide a comparative analysis of the photodegradation of drug molecules using UVC rays with and without the ZnO catalyst. Ibuprofen (IBP) and clotrimazole were used for analysis. We found that the use of a ZnO catalyst did not always produce better results. In some cases, we found that IBP was degraded more without ZnO (up to 94.4%) than with the ZnO (1 g/L) (up to 86.6%) in 60 min. However, without ZnO, we observed secondary metabolite by-products of IBP that required a longer treatment period to fully degrade. The inferior degradation strength for treatment with ZnO could be explained by increasing turbidity from adding greater concentrations of ZnO, which decreased the UV transmission to the IBP solution. To support the results, an investigation of the photocatalytic degradation of clotrimazole (an antifungal) with varying concentrations of ZnO as a catalyst was also carried out. The optimum ZnO concentration was determined to be ~1000 ppm, above or under which the efficiency of the degradation suffered. Thus, the use of a ZnO catalyst requires strict dosage control. Such tight regulation is not required for the system using just UVC rays, but it requires a longer treatment time to completely degrade the drug molecules and their by-products.
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