engleski

Optimization of imidacloprid photocatalytic degradation under UVA-LED irradiation conditions

This research deals with the photocatalytic degradation of the neonicotinoid insecticide imidacloprid. The reaction was carried out in a flat plate photoreactor in recirculated batch mode over an immobilized layer of a nitrogen-doped TiO2 photocatalyst. The characterization of the prepared photocatalyst was performed using different instrumental techniques. The irradiation sources used were UV 365 nm high power LEDs with different power (20 and 30 W) and irradiation intensities. The radiation intensities were changed by adjusting the voltage supplied to the UVA-LED radiation source. Design of experiments was used to evaluate the influence of three selected variables such as initial concentration of imidacloprid solution, pH, and UVA-LED irradiance on the photodegradation efficiency. Doping the photocatalyst with nitrogen using urea as the nitrogen source leads to a decrease in the bandgap, Eg, compared to the characteristic values obtained for the commercial unmodified TiO2-P25 photocatalyst (2.92 +/- 0.021 eV vs 3.38 +/- 0.015 eV). Analysis of the results using the Design- Expert software package showed that irradiance was the most significant factor in the process studied. Treatment of TiO2 with urea is more efficient method of TiO2 modification than the N2 plasma pretreatment which resulted in a smaller decrease in Eg. The statistical parameters of the model equation obtained from ANOVA confirmed the satisfactory fit of the proposed reduced cubic model to the experimental data. The results of the kinetic analysis showed that the photocatalytic degradation of imidacloprid can be described by pseudo-first order kinetics.

flat-plate photoreactor (FPP) ; nitrogen-doped TiO2 (N-TiO2) ; UVA-LED irradiation source ; imidacloprid ; design of experiments (DoE) ; kinetics

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