Prediction of carbofuran degradation based on the hydroxyl radical's generation using the Fe^III impregnated N doped-TiO₂/H₂O₂/visible LED photo-Fenton-like process

Hydroxyl radicals (^[rad]OH) are the dominant reactive species during most photocatalytic reactions. Therefore, ^[rad]OH generation as an index could be beneficial in comparing the obtained results in different experimental setup designs, thereby providing new insights for understanding the photocatalytic mechanism. Heterogeneous photo-Fenton like processes are one of the most effective technologies for degradation of organic pollutants through ^[rad]OH production. Nevertheless, kinetic models that take into account the dependence of the contaminant degradation on ^[rad]OH generation under homogeneous oxidant supply, are still limited in such processes. In this paper, a photo-Fenton like reagent (Fe^III impregnated N-doped TiO₂ (FeNT)/H₂O₂) involving both heterogeneous and homogeneous phases was employed for carbofuran (CBF) degradation, frequently used pesticide in many developing countries from the carbamate group. In addition, a commercial visible LED lamp (Vis LED) with high power output was utilized as an innovative and efficient visible light source to simulate solar energy. Accordingly, a new kinetic model was proposed to predict CBF degradation in the FeNT/H₂O₂/Vis LED process under high Vis LED light intensities based on intrinsic reaction parameters, including the Vis LED light intensity, FeNT dosage, initial H₂O₂ concentration, and ^[rad]OH generation. The developed model was verified and validated successfully under various reaction conditions. However, a standard error ranging from 3% to 15% was observed at extreme cases such as high [FeNT] and I or low [H₂O₂]₀ when comparing model predictions and experimental results. This is due to the use of averaged conditions to forecast the rate constants.