Davide Vione

CHAPTER 13:Photodegradation of Drugs/Illicit Drugs in Water

Licit and illicit drugs, once discharged into the environment, can follow different transformation routes. Direct or sensitized phototransformations in natural aquatic media are important environmental depletion mechanisms for drugs. Light can promote the complete degradation of the molecule, but in some could promote the formation of transformation products that are more toxic and/or harmful than the parent compounds. In this chapter, we focus on the photoinduced processes, with particular emphasis on the drug’s phototransformation.

Modelling On Photogeneration Of Hydroxyl Radical In Surface Waters And Its Reactivity Towards Pharmaceutical Wastes

This paper reports a simple model to describe the formation and reactivity of hydroxyl radicals in the whole column of freshwater lakes. It is based on empirical irradiation data and is a function of the water chemical composition (the photochemically significant parameters NPOC, nitrate, nitrite, carbonate and bicarbonate), the lake conformation best expressed as the average depth, and the water absorption spectrum in a simplified Lambert‐Beer approach. The purpose is to derive the lifetime of dissolved molecules, due to reaction with •OH, on the basis of their second‐order rate constants with the hydroxyl radical. The model was applied to two compounds of pharmaceutical wastes ibuprofen and carbamazepine, for which the second‐order rate constants for reaction with the hydroxyl radical were measured by means of the competition kinetics with 2‐propanol. The measured values of the rate constants are 1.0×1010 and 1.6×1010u2009M−1u2009s−1 for ibuprofen and carbamazepine, respectively. The model suggests that the lif...