Methotrexate degradation by UV-C and UV-C/TiO2 processes with and without H2O2 addition on pilot reactors

Methotrexate (MTX) is an anti-cancer drug that can be excreted up to 90% after administration due to its low biodegradability. Advanced Oxidation Processes (AOPs) are a feasible alternative for the elimination of MTX in the environment. In this research, AOPs were performed in specialized patented reactors (UBE Photocatalytic systems and BrightWater Titanium Advanced Oxidation Process) under experimental pilot conditions. Photolysis and heterogeneous photocatalysis (UV and UV/TiO2) experiments were performed with and without addition of H2O2 and at different initial pHs. Best degradation percentage was achieved by photolysis when initial pH was 3.5 and added H2O2 was 3 mM, reaching a MTX degradation of 82% after 120 min of reaction. HPLC-MS analysis of the resulting samples showed four possible byproducts of MTX degradation, which presented a higher ecotoxicity than the starting compound.