Comparative Analysis of Photodegradation of Ibuprofen and Clotrimazole Water Pollutant using UVC Rays in presence and absence of ZnO Photocatalyst

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 are focused on 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 photodegradation of drug molecules using UVC ray with and without the ZnO catalyst. Ibuprofen (IBP) and clotrimazole are used for analysis. We found that the use of ZnO catalyst does not always produce better results. In some case, we found that IBP was degraded up to 94.8% more than that with the ZnO up to 91.4% in 60 mins. However, without ZnO we observed secondary metabolite by-products of IBP that require longer treatment period to fully degrade. The inferior degradation strength for treatment with ZnO can be explained by increasing turbidity from adding greater concentrations of ZnO which decreases the UV transmission to the IBP solution. To support the results, an investigation on the photocatalytic degradation of clotrimazole, an antifungal, with varying concentrations of ZnO as catalyst was also carried out. The optimum ZnO concentration was determined to be ~1000 ppm, above or under which the efficiency of the degradation suffers. Thus, the use of ZnO catalyst require strict dosage control. Such tight regulation is not required for the system using just UVC ray, but it would require a longer treatment time to completely degrade drug molecules and its by-products.