Phototransformations of selected pharmaceuticals under low-energy UVA–vis and powerful UVB–UVA irradiations in aqueous solutions—the role of natural dissolved organic chromophoric material

摘要: The kinetics of simulated low-energy daylight (UVA–vis) and powerful combined ultraviolet B A (UVB–UVA) induced direct indirect phototransformations four pharmaceuticals, i.e., ibuprofen, metoprolol, carbamazepine, warfarin, which were investigated in dilute solutions pure laboratory natural humic waters. results strengthen the essential function chromophores dissolved organic material (CDOM) as principal photosensitizer toward pharmaceuticals conditions under available UVA–vis slight UVB radiations. confirmed that micropollutants are able to undergo a photolysis if their absorbance spectra overlap spectral range radiation but only is strong enough, e.g., ibuprofen via different pathways all realistic conditions. action nitrate anions photosensitizers applied proved be little importance. High-performance size-exclusion chromatographic experiments verified rate constants obtained UVB–UVA irradiations for decreased amounts two largest molecular size fractions CDOM quite close detected increased next five with smaller sizes. contents correlated well studied irradiation process somewhat less irradiation. photochemically decomposition aggregates appears increase simultaneously produce CDOM-stimulated radical reactions structural transformations pharmaceuticals. Apparent quantum yields estimated transformation–degradation molecular-size irradiations.