Heterogeneous photocatalysis is one of the advanced oxidation processes (AOP) for the removal of poorly degradable organic as well as some inorganic substances. In the method, a semiconductor is used as a photocatalyst, which is inserted into the reactor, and the photocatalytic reaction is carried out by illumination with UV or visible light.
Various types of reactor systems are used in both laboratory and industrial settings to perform photocatalytic reactions. The reactors are divided into three groups according to the type of photocatalyst used (suspended/immobilized), the type of radiation (UV/VIS/sunlight) and the location of the radiation source used (immersed/external/distributed).
In the experimental part of the work, we investigated the efficiency of photocatalytic degradation for selected organic pollutants. Solutions of organic dye plasmocorinth B and pharmaceuticals ciprofloxacin and oxytetracycline hydrochloride were used. UV-VIS spectroscopy and HPLC methods were used to monitor the adsorption of each pollutant in the dark and to determine the photocatalytic efficiency of TiO2. This was immobilized on glass beads loaded into the tube of the photoreactor cell. In the case of the dye solution, the stability of the deposit was monitored by repeated use of the catalyst.
In the case of repeated photocatalysis of plasmocorinth B solution, we found that the immobilized TiO2 is not washed off during the degradation of the pollutant, which allows its repeated use. The efficiency of photocatalytic degradation was demonstrated with a ciprofloxacin solution, which was 95% degraded. For these solutions, the contaminant concentration was monitored by UV-VIS spectroscopy. Then, the degradation of oxytetracycline hydrochloride solution was studied, and HPLC measurements showed the formation of an intermediate, which was then successfully degraded.
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