Estimation of photocatalytic degradation rate using smartphone based analysis

A simple approach to test photocatalyst activity has been described. Photocatalytic degradation of a model dye was measured using a smartphone. The color changes were registered directly in the micro-photoreactor. The model dye Rhodamine B was degraded under UV irradiation (365 nm). The effect of H2O2 concentration and titanium dioxide photocatalyst dosage has been studied. Among three color systems, RGB, CIE L*a*b* and HSV, the first one proved to be the most suitable for the dye determination. The reference measurements were carried out with a UV-Vis spectrophotometer. Two smartphones and two tablets with different camera resolutions have been examined. The best calibration curve was obtained using a Samsung Galaxy A6 smartphone with a 16MP camera. The t-test has shown with 95 % confidence that there are no significant differences between the dye concentrations measured with the smartphone and spectrophotometer. The values of the relative standard deviation of the smartphone measurements were less than 0.5 %. Therefore, the proposed method for fast estimation of photocatalyst activity can be used in the control of advanced oxidation reactions.