Photosynthesis-inspired design approach of a liquid phase heterogeneous photoreactor

A method of photocatalytic process intensification, which can be easily used for efficient photoreactor design, inspired by the mechanism of natural photosynthesis was developed and the possible mechanism was proposed. Four model compounds (phenol, Cr(VI), acid orange 7 and p-nitrophenol) with different photocatalytic reaction mechanisms, and using a Kenics static mixer, were selected to perform experiments for validation. Experimental results showed that the static mixer can intensify the indirect radical-mediated mechanism reaction, but had no effect on the direct surface reaction mechanism reaction. Meanwhile, both the illuminated static mixer and dark static mixer had similar intensification effects. Herein, we propose that the role the static mixer played in heterogeneous photocatalysis is the creation of intense mixing and increasing the interfacial mass transfer, which resulted in the enhanced mobility of reactive radicals from the catalyst surface or boundary layer to solution, thus intensifying the whole photocatalytic efficiency. Furthermore, the proposed separation of the illumination part and the mixing part for photoreactor design allows for easier scale-up and engineering applications.