TPPS₄—Sensitized Photooxidation of Micropollutants—Singlet Molecular Oxygen Kinetic Study

Abstract

Visible light-sensitized oxidation of micropollutants (MPs) in the presence of meso-tetrakis(4-sulfonatophenyl)porphyrin photosensitizers was studied. In order to explore the role of type I (ROS generation) or type II (singlet oxygen) photooxidation, radical scavengers were used to obtain insight into the mechanism of photodegradation. It was revealed that singlet oxygen is the main ROS taking part in TPPS4- sensitized photooxidation of micropollutants. The interaction of MPs with 1O2 in deuterium oxide (D2O) was investigated by measuring the phosphorescence lifetime of 1O2. The rate constant (kq) for the total (physical and chemical) quenching of 1O2 by MPs was determined in a D2O buffer (pD 7, 9 and 10.8). The rate constants of singlet oxygen quenching and reaction with MPs were determined, and the rate constant of excited TPPS4 quenching by MPs was also estimated.

Keywords

• singlet oxygen
• reaction rate constants
• photooxidation
• photosensitizer
• kinetic