Removal of the chemotherapeutic drugs 5-fluorouracil and cyclophosphamide by UV/peracetic acid: Reaction kinetics and mechanism

Abstract

5-Fluorouracil and cyclophosphamide, the two most commonly used chemotherapeutic drugs, are widely detected in aquatic environments and cause cytotoxic and other adverse effects in ecosystems. In this work, UV/peracetic acid (UV/PAA) treatment was investigated for the first time for 5-fluorouracil and cyclophosphamide removal. The results showed that 5-fluorouracil and cyclophosphamide can be efficiently removed via UV/PAA within 20 min, with pseudo-first-order rate constants (kobs) of 0.197 and 0.135 min−1, respectively. The influences of PAA dosage, initial compound concentration, solution pH and common water constituents (Cl−, HCO3−, NO3− and dissolved organic matter) were systematically studied. OH was the predominant species involved in the degradation of the two pharmaceuticals, while direct UV photolysis and R–C were also involved in removing 5-fluorouracil. Two and five byproducts were detected in UV/PAA degradation of 5-fluorouracil and cyclophosphamide, respectively, and the possible degradation pathways were proposed. Although total organic carbon was not completely removed during the reaction, the Microtox® toxicity trend (an increase and further decrease) implied further detoxification of the byproducts. Additionally, UV/PAA treatment applied to real water samples (river water and effluent from a wastewater treatment plant) still exhibited good efficiency for removing the two compounds, revealing its applicability in water/wastewater treatment.