Photocatalytic reactors and their scale up: literature review

Abstract

Photocatalysis reactions have been extensively studied for the degradation of recalcitrant substances. It is known that the activation of the photocatalyst occurs with the absorption of photons of energy greater than or equal to the band gap, causing electrons from the valence band to be transferred to the conduction band, resulting in a gap in the valence band. On a laboratory scale, many works have already been developed. The most used configuration is the cylindrical reactor, where the light source is placed in the center, immersed in the reaction medium, protected by a quartz cell. Xenon, LED and mercury lamps are the most used due to the wavelength at which they emit electromagnetic radiation. Heterogeneous catalysts are also used to improve the efficiency of the process, but when used dispersed in the medium, there is a difficulty in separating them after the operation, and when used immobilized, there are barriers related to their fixation in the system. For the scale up, a change in the lighting source to sunlight, replacement of quartz by glass, and different ways of reusing the catalysts for greater economy were observed.