Ag-TiO2 assisted photocatalytic degradation of cytostatic drug cyclophosphamide under UV-vis light

Abstract

Cyclophosphamide (CP) is a commonly prescribed cytostatic drug that has cytotoxic, genotoxic, mutagenic, carcinogenic and teratogenic effects on living organisms, which asks for its elimination from any water source. The photocatalytic degradation of CP under UV-VIS irradiation was studied, using non-doped TiO2 and Ag- doped TiO2 (0.5-1.7% wt.). The catalysts were synthesized by vacuum deposition method. The influence of Ag concentration on the degradation performance of CP was investigated and an optimal content of 1.0% Ag was established. Using of this catalyst assures the pollutant degradation with a rate constant kCP = 6.59 x 10-4 s-1 and an efficiency ηCP = 99% after120 min irradiation time. Based on the results of the quenching experiments in the presence of suitable scavengers, a mechanism of photocatalytic degradation of CP has been proposed. This consists in the attack of free hydroxyl radicals and superoxide radicals on the pollutant. Also, the contribution of Ag to inhibition of charge recombination and the additional generation of superoxide radicals, which are responsible for the higher photocatalytic activity of Ag doped TiO2 compared to non-doped TiO2, was emphasised.