Novel continuous in situ measurement of photocatalyst efficiency in liquid dispersions by laser absorption method

This work presents a novel method and reactor design for measuring photocatalytic activity. This method allows continuous in situ monitoring of the decrease in pollutant concentration in a liquid dispersion containing the tested photocatalyst. Due to the presence of the photocatalyst in the liquid dispersion, the standard Beer-Lambert absorption law cannot be used directly to determine pollutant concentration in photocatalytic measurements. Therefore, the presented in situ measurement method also utilizes a newly derived modification of the absorption law, which, in addition to absorption, also considers the scattering effect caused by the dispersed photocatalyst. Repeated correlation analysis showed an average deviation of only 1.04% from approximately 500 measurements. At the same time, the measured points obtained by the presented method were within the uncertainty intervals of the standard method for measuring photocatalytic activity. It has been demonstrated that this novel continuous in situ measurement method can replace the current standard measurement method and can provide an even more consistent and faster way of testing photocatalytic materials. In addition, a novel and open source (patented experimental setup for the photocatalytic reactor system, consisting of a spectrometric laser and probe, is fully described in this paper.