Kinetics of Ozonation of 2-Mercaptothiazoline in an Electroplating Solution Combined with UV Radiation

Abstract

The enhanced ozonation of 2-mercaptothiazoline (2-MT) with ultraviolet (UV) radiation in the acid-based electroplating solution of the printed wiring board industry was studied. The substrate prescription of the electroplating solution is with high concentrations of copper sulfate, sulfuric acid, and chloride ions. Note that the contribution of the present work includes investigation of the effect of UV radiation and construction of the refined model for the O3/UV treatment of 2-MT. The catalysis of UV radiation is found to be significant for the enhancement of the mineralization rate in the ozonation of 2-MT. Furthermore, the multistep reaction kinetics has been proposed to describe the concentration variations of 2-MT, total organic carbons, dissolved ozone, and off-gas ozone in the course of ozonation. This comprehensive kinetics for the ozonation of 2-MT combined with UV radiation is developed in association with the previous study of the sole ozonation of 2-MT in the electroplating solution. The enhancement factor of the gas−liquid mass transfer of ozone is simultaneously considered by the ozonation model. The obtained results can provide useful information for modeling the removal of additives such as 2-MT in the electroplating solution of the printed wiring board industry by the ozonation with 254-nm UV light radiation.