Dimer formation during UV photolysis of diclofenac

Diclofenac removal by simulated solar assisted photocatalysis using TiO2-based zeolite catalyst; mechanisms, pathways and environmental aspects

“…5, there are three main routes. If the "ring-closure" route is considered as dominant for direct photolysis [25,39,41], which was negligible in our study ( Fig. 4.…”

“…However, these structures were not detected by the HPLC/MS/MS analyses employed in this study. Besides, structures 5 and 6 are more typical for direct photolysis [25,38,39,41]. Taking into account that open-ring products are mostly not chlorinated due to the fact that saturation of benzene ring, which precede ring-opening, usually occurs upon elimination of chloro-and amino-groups and subsequent hydroxylation, the remain chlorine bonded to organic structures can be contributed to single-benzene ring structures.…”

“…5). Such by-product is recognized as the main structure formed by direct photolysis, including solar irradiation[25,39,41]. Another possibility within 2 nd route considers initial hydroxylation of phenylacetic acid moiety, yielding ring closure and subsequent formation of indoline derivative (6,Fig.…”

Novel pilot scale continuous photocatalytic membrane reactor for removal of organic micropollutants from water

“…The maximum UV absorption of DCF was found at 278 nm in neutral and alkaline solutions, whereas in acidic solution a decrease was observed both in the absorbance and in the maximum wavelength (271 nm). The latter can be attributed to the reduced water solubility of the acidic DCF in its non-ionized form (pKa=4.15) [22].…”

Degradação de fármacos em meio aquoso por meio de fotólise e peroxidação fotoassistida.

“…No caso da mistura de fármacos, a Equação (21) Observa-se que os comportamentos dos espectros são bastante similares entre si, com exceção do diclofenaco (DIC), para o qual se nota que a curva correspondente ao tempo zero está inferior às demais após os experimentos de fotólise; isso está associado à coloração formada (alaranjado) após o processo de fotólise, o que, segundo Keen et al (2013), deve-se à formação de dímero (subproduto 5 -Figura 11) durante a radiação (UV) do DIC. Para os outros fármacos sempre há redução da absorbância com o decorrer da fotólise, o que se deve a sua degradação.…”