Industrial Chemistry

Biography

Biography: Katarzyna Piwowar

Abstract

Photoexcitation of atmospheric oxygen by several photosensitizers leads to generation of singlet oxygen molecule having exceptionally high oxidation potential. Due to its millisecond lifetime a continuous, in situ generation is required in the environment in which it is reacting. This strategy is a case of green technology which employs sunlight energy to improve the efficiency of many processes, especially in organic synthesis or wastewater treatment. Novel heterogeneous systems generating singlet oxygen seem to be a perspective option for an application of singlet oxygen oxidation capacity. These systems involve two phases with the active interface. The first phase consists a photosensitizer, which is responsible for singlet oxygen generation, and the second holds the species being oxidized. The photoactive phase should combine an effective solar radiation absorption and the direct energy conversion together with a high photostability, whereas the second accumulates the oxidized product. We report on oxidation of organic model compounds like phenol, citronellol or α-terpinen in two types of heterogeneous systems. First, with a solid material as an active phase, and second with a liquid solution. Photo-active material was prepared by simple electrochemical method using electropolymerization of well-known photosensitizers - phenothiazines. The liquid-liquid phase contain the liquid active phase in which the photosensitizers are dissolved in common organic solvents or in ionic liquids. Under visible light illumination these heterogeneous systems were able to generate singlet oxygen directly to the interface with the second phase where it was employed in the oxidation process. The effectiveness of the process was monitored by UVVis spectroscopy and the activation was achieved by diode laser with the excitation wavelength at 638 nm.