Modelling approaches to predict light absorption in gas-liquid flow photosensitized oxidations

Photo-Oxidation in Three-Phase Flow with Continuous Photosensitizer Recycling

“…The stabilization of conversion for G/L/L:35/15/50 and G/ L/L:50/15/35 at ∼35% above RB concentrations of 0.1 mM correlates with the increasing light attenuation, as 61.04% of the incident light is absorbed at 0.1 mM (Table S7). Additional possible reasons are the presence of mass transfer limitations observed in gas/liquid flow for RB concentrations above 0.2 mM, 14 the quenching of singlet oxygen by excess RB molecules, 10 and the formation of RB aggregates in water. 55 The experiments were also conducted without RB under the same conditions, and the results are displayed in Table S3.…”

“…The characteristics of the three-phase flow were analyzed by acquiring images of the entire microreactor channels. This method developed by our group has successfully been applied for two-phase flow characterization in the same reactor. , Images were obtained using a full-frame complementary metal oxide semiconductor (CMOS) sensor camera (Nikon, D810) and a 24–70 mm lens (Nikon, AF-S NIKKOR) with a focal length of 35 mm and an f -number of 2.8. A shutter speed of 1/3200 s and a resolution of 7360 × 4912 pixels were used for this purpose.…”

“…The formation and use of singlet oxygen are increasingly investigated in photochemical flow reactors. ,− Microreactors having high surface-to-volume ratios and accompanied short optical pathlengths provide a suitable environment for photosensitized oxidations due to enhanced mass transfer properties and precise control over reaction time that minimizes side reactions. − Moreover, performing the photo-oxidations in multiphase flow brings improved mass transfer compared to single-phase flow . Jacobs et al compared the efficiency of photo-oxidation of 9,10-diphenylanthracene in single- and two-phase (gas/liquid) Taylor flow and reported that higher conversion is obtained for two-phase conditions .…”