engleski

Photocatalytic degradation of acetamiprid in a rotating photoreactor – determination of reactive species

The development of photocatalytic systems has led to great advances in environmental remediation and environmentally friendly energy production. Due to their high efficiency and potential to remove various priority pollutants, the focus of modern research is to overcome existing challenges, which include several key parameters, such as the distribution of radiation intensity, suitable modifications of photocatalysts to extend the range of their catalytic activity in the visible light region, the preparation of an immobilized layer of photocatalysts on a suitable substrate, the preparation of stable and efficient photocatalysts for use in real systems, etc. With rapid industrialization, the number of priority pollutants has increased significantly, so their removal from the environment requires the use of advanced oxidation processes as a promising technology. Acetamiprid (N-[(6-chloropyridin-3-yl)methyl]-N'- cyano-N-methylethanimidamide ; C10H11ClN4) is a commonly used neonicotinoid insecticide in practice due to its exceptional insecticidal activity, broad spectrum of activity, high stability and water solubility. However, due to its long half-life, it can accumulate in many plants and microorganisms, leading to adverse effects on human health (toxicity, carcinogenicity, mutagenicity). Therefore, it is extremely important to develop a reliable and effective technique for its removal from the environment. There are several types of photoreactors used for photocatalytic degradation of various persistent and toxic organic compounds in an aqueous medium. In this work, an advanced design of a photoreactor was used which was developed considering the basic methodology of process intensification. Photocatalytic degradation of acetamiprid was studied in a rotating photoreactor with recirculation of the reaction mixture using an immobilized layer of TiO2 photocatalyst. Two 15 W UV-A lamps were used as an external source for photoinduced excitation of the photocatalyst, and modified TiO2 was used as the photocatalyst. The modification of TiO2 was carried out to decrease its band gap energy and shift its photoactivity to the visible light region. The aim of the study was to determine the reactive oxygen radicals and to investigate the influence of some interfering compounds, crucial for the successful performance of the photocatalytic degradation of the selected model component. For this purpose, various scavengers were used that exhibit high reactivity with individual oxygen and other reactive species. Based on the determination of the change in concentration of the model component as a function of irradiation time, conclusions were drawn about the efficiency of photocatalytic degradation. The experimentally obtained results during photocatalytic degradation were tested with the adopted reactor and kinetic model, and the model parameters were estimated. The analysis of the obtained results showed that superoxide anion radicals and singlet oxygen play a crucial role in the photocatalytic degradation mechanism of acetamipride. In the presence of low concentrations of hydrogen peroxide, the efficiency improves, which is explained by the formation of additional superoxide anion radicals. In the presence of potassium persulfate, the degradation of acetamiprid is significantly improved due to the formation of sulfate radicals, which are extremely strong oxidants. Based on the obtained results, recommendations were made for future research to determine the role of reactive oxygen radicals, which are crucial for the successful performance of photocatalytic degradation.

photocatalytic degradation ; acetamipride ; rotating photoreactor

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