The effects and the toxicity increases caused by bicarbonate, chloride, and other water components during the UV/TiO degradation of oxazaphosphorine drugs.

The influences of HCO, Cl, and other components on the UV/TiO degradation of the antineoplastic agents ifosfamide (IFO) and cyclophosphamide (CP) were studied in this work. The results indicated that the presence of HCO, Cl, NO, and SO in water bodies resulted in lower degradation efficiencies. The half-lives of IFO and CP were 1.2 and 1.1 min and increased 2.3-7.3 and 3.2-6.3 times, respectively, in the presence of the four anions (initial compound concentration = 100 μg/L, TiO loading =100 mg/L, anion concentration = 1000 mg/L, and pH = 8). Although the presence of HCO in the UV/TiO/HCO system resulted in a lower degradation rate and less byproduct formation for IFO and CP, two newly identified byproducts, P11 (M.W. = 197) and P12 (M.W. = 101), were formed and detected, suggesting that additional pathways occurred during the reaction of •CO in the system. The results also showed that •CO likely induces a preferred ketonization pathway. Besides the inorganic anions HCO, Cl, NO, and SO, the existence of dissolved organic matter in the water has a significant effect and inhibits CP degradation. Toxicity tests showed that higher toxicity occurred in the presence of HCO or Cl during UV/TiO treatment and within 6 h of reaction time, implying that the effects of these two anions should not be ignored when photocatalytic treatment is applied to treat real wastewater.