Influence of UV Lamp Configuration on the Degradation, Transformation Products, and Toxicity of Emerging Contaminants in Rainwater During Photolysis and TiO2 Photocatalysis

This study compared the degradation of twelve emerging organic contaminants in rainwater by direct photolysis and TiO2-assisted heterogeneous photocatalysis using two UV lamp configurations with different emission spectra and wavelength-specific radiant fluxes ranging from 297 to 578 nm. Differences in micropollutant degradation were observed between the two lamp configurations; however, because their wavelength-specific radiant fluxes differed, these effects cannot be attributed exclusively to the spectral distribution of the emitted radiation. The presence of TiO2 increased the degradation of the investigated organic compounds; only for butylated hydroxytoluene (BHT), triallate (TRI) and oxadiazon (ODZ) were higher removal efficiencies observed during direct photolysis. The analysis of the kinetics of the process led to the conclusion that the type of UV lamp affects the rate of decomposition of micropollutants. GC–MS analysis revealed several transformation products, which were tentatively identified by comparison of their EI mass spectra with the NIST 17 mass spectral library. A greater number of transformation products was detected in samples irradiated with the TQ lamp than in those treated with the TQ-Z2 lamp. Toxicological analysis showed that the toxicity of some treated samples increased during irradiation, coinciding with the detection of transformation products. However, the contribution of individual transformation products to the observed toxicity could not be established.