High throughput screening of photocatalytic conversion of pharmaceutical contaminants in water

The susceptibility for photon-induced degradation of over 800 pharmaceutical compounds present in the LOPAC¹²⁸⁰ library, was analyzed by UV/Vis spectroscopy in the absence or presence of TiO₂ P25 in water. In general, few compounds were effectively degraded in the absence of the TiO₂ photocatalyst (3% of all compounds tested), while in the presence of TiO₂, the majority of compounds was converted, often to a large degree. Differences in degree of degradation are evaluated on the basis of molecular weight, as well as the chemical nature of the drug compounds (functional groups and pharmacological classes). In general, if the molecular weight increases, the degradation efficacy decreases. Relatively high degrees of conversion can be achieved for (relatively small) molecules with functional groups such as aldehydes, alcohols, ketones and nitriles. A low degree of conversion was observed for compounds composed of conjugated aromatic systems. Trends in degradation efficacy on the basis of pharmacological class, e.g. comparing hormones and opioids, are not obvious.