engleski

Optimization of photocatalytic degradation of neonicotinoids under UVA-LED irradiation conditions using the response surface methodology

Population growth and increasing food demand require a shift from traditional to modern and intensive agricultural production, leading to increased use of insecticides. Neonicotinoid insecticides, including imidacloprid, have been added to the European Commission’s expanded “Watch” list within the Water Framework Directive since 2018, due to confirmed risk and danger to the aquatic environment. In this work, photocatalytic degradation of imidacloprid was investigated using immobilized TiO2 and two UVA-LED modules as irradiation source. A suitable mineral binder and an abrasive material as a support were used to prepare a stable immobilized photocatalytic layer with acceptable mechanical properties. Surface functionalization of TiO2 with urea was carried out to reduce the energy band gap (Ebg) of TiO2 as confirmed by UV-Vis diffuse reflectance spectroscopy (DRS). The chemical and structural properties of the catalyst were investigated by X- ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX). Photolytic and photocatalytic experiments were performed in the flat-plate photoreactor in recirculated batch mode, equipped with two UVA-LED modules connected to a voltage source. The intensity of the radiation was changed by applying a different voltage to the module. Influences of different process parameters such as initial concentration of imidacloprid, irradiation intensity and pH were studied using response surface methodology (RSM). An experimental design was prepared using Design-Expert. The kinetic study was also carried out for imidacloprid photodegradation at optimum conditions. According to the results of the model, the predicted response values showed high agreement with the actual response values. Finally, the model was found to be suitable for the design conditions of the experiment.

photocatalytic degradation ; imidacloprid ; immobilized TiO2 ; Design-Expert

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