The presence of pharmaceutical pollutants in the aquatic environment has become an increasing environmental concern, as many pharmaceutical compounds, due to their chemical stability, pass through conventional wastewater treatment processes and consequently accumulate in surface water and groundwater. Therefore, an increasing amount of research is focused on the development of advanced oxidation processes, among which photocatalysis has emerged as one of the most promising technologies for the degradation of persistent organic pollutants.
In this bachelor's thesis, tin oxysulfide was investigated as a potential photocatalyst for the photodegradation of pharmaceutical pollutants. Particular attention was paid to its properties, as the combination of oxygen and sulfur enables efficient light absorption. The fundamental mechanisms of photocatalysis and the factors influencing the efficiency of organic compound degradation are also presented.
The experimental part includes the synthesis of tin oxysulfide using a precipitation method mediated by garlic extract, the improvement of catalyst properties by silver modification, its characterization using appropriate analytical techniques and the evaluation of its photocatalytic efficiency in the degradation of selected pharmaceutical compounds. The concentrations of the pharmaceutical compounds were determined by high-performance liquid chromatography (HPLC) and the obtained results were used to evaluate which photocatalyst was more effective in degrading the pharmaceuticals. The photocatalytic experiments were performed using a mixture of five different pharmaceutical compounds in water under both UV and visible light irradiation.
The results showed that, under the experimental conditions used, significant photocatalytic degradation was observed only for diclofenac, whereas no degradation was detected for the other four pharmaceutical compounds. Diclofenac was selectively degraded by both photocatalysts (unmodified and silver-modified tin oxysulfide) under both light sources. The highest degradation efficiency was achieved with silver-modified tin oxysulfide under visible light irradiation.
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