Pt-TiO2-assisted photocatalytic degradation of the cytostatic drugs ifosfamide and cyclophosphamide under artificial sunlight

The aim of this work was to develop an effective photocatalytic technique for the removal of two cytostatic drugs from water. To this end, the kinetics, efficiency and decomposition pathway of the photocatalytic decay of ifosfamide (IF) and cyclophosphamide (CF) was investigated. The samples of Pt-doped (0.15 at.%) and undoped TiO2 photocatalysts were prepared by a simple sol-gel method and then structurally characterized. The effects of operating parameters such as loading of photocatalyst, drug concentration, and photoactivity in solar and visible light were studied. The degradation processes in both drugs followed a pseudo-first-order kinetics. A degradation mechanism was proposed based on the identification of inorganic intermediates (NH4+, Cl−, PO43−) and organic by-products. The results showed that PO43− ions released during the decomposition of drugs were adsorbed on the photocatalyst, but this phenomenon had no negative effect on its photoactivity. The experimental results of the reactive species quenching showed that OH radicals were the predominant oxidant species participated in reaction, and the oxidation of drugs occurred in the bulk solution. Moreover, Pt-doped TiO2 was more effective at generating OH radicals than TiO2, probably due to the significantly promoted electron/hole separation in the modified photocatalyst. The results also demonstrated that the decomposition pathways of IF and CF differed.