engleski

Photocatalytic degradation of imidacloprid under natural sunlight

Pollution of the environment, especially of the aquatic ecosystem, is one of the most serious problems today. Due to their high toxicity, strong bioaccumulation in the environment and high persistence, a relatively new group of insecticides - neonicotinoids - pose a serious threat to the ecosystem and the health of living organisms. Since conventional water treatment methods do not allow the complete removal of pesticides from polluted waters, a large amount of scientific research today is focused on the development of environmentally friendly and energy-efficient treatment methods. Heterogeneous photocatalysis is carried out in the presence of a solid semiconductor material and under the influence of sunlight as a radiation source. Due to its properties such as high photochemical stability, oxidative efficiency, availability and non-toxicity, the most commonly used photocatalyst is titanium dioxide (TiO2). Despite its many advantages, the high energy of the bandgap, i.e., the need for UV radiation for excitation, is a factor limiting the use of TiO2 in solar systems. In this work, photolytic and photocatalytic degradation of the neonicotinoid insecticide imidacloprid was investigated with Sun as a radiation source. Investigations were carried out in a plate photoreactor under recirculating reaction conditions with an immobilized photocatalyst (TiO2). To reduce the bandgap, TiO2 was modified by prior irradiation with UVC radiation. The experiments were performed at a constant initial reactant concentration (10 ppm) and at a constant pH of the reaction solution (pH = 6.5). The influence of the recirculation flow (50 - 300 cm3 min-1) and the surface area of the photocatalyst exposed to radiation on the rate of degradation of the model component was studied. The course of imidacloprid degradation was followed by high performance liquid chromatography (HPLC), while the degradation intermediates were identified by QTof analysis. The test results indicated the possibility of photocatalytic degradation of imidacloprid using Sun, a clean and alternative energy source, as a radiation source. In the presence of the prepared photocatalyst, the reaction rate is significantly increased. Higher conversions of imidacloprid were achieved at higher recirculation flows and larger surface area of the photocatalyst exposed to radiation.

photolysis ; photocatalysis ; imidacloprid ; Solar radiation

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