A study of photooxidation reaction in a novel batch oscillatory baffled photoreactor

Abstract

The work of this thesis focuses on a kinetic investigation into a photooxidation reaction between α-terpinene and singlet oxygen (1O2), involves several initiatives, and has generated a number of new results. Firstly, a novel batch Oscillatory Baffled Photo Reactor (OBPR) was employed in this work, LEDs were planted evenly on the surfaces of orifice baffles that move up and down the column, providing uniform light distribution. In addition, the OBRP has excellent capabilities of multiphase mixing and solid suspension. In this context, polymer supported Rose Bengal (Ps-RB) beads were used as the photosensitizer, the conversion rate achieved in this study ranged between 20-30%, which is higher than similar studies that used a different type of photosensitizer. Compared to existing studies, this work contributes novel insights into the use of oscillatory baffled reactors for photooxidation reactions, especially in the context of using a mobile photosensitizer. Secondly, the widely used NMR data analysis for determining ascaridole and α-terpinene was examined by carrying out detailed kinetic assessment of the photooxidation reaction, for the first time, conditions were identified where the data analysis is valid or invalid. Thirdly when the data analysis is valid, a methodology of quantifying the concentration of singlet oxygen was, for the first time, proposed, the concentrations so generated compared well with these from the kinetic analysis. Fourthly, definitions and methods of evaluating the efficiency of singlet oxygen utilization and the efficiency of photo conversion from molecule oxygen to singlet oxygen were, for the first time, proposed, this provides the insight of inefficiency of the reaction process. Fifthly, parameters affecting kinetics were investigated, including the mass of the beads, mixing, air flow rate, light intensity and wavelength. Finally, the durability of the Ps-RB beads was examined, the decay of activity was evaluated.