A visual comparison of the gas-liquid characteristics with increasing rotation speed can be observed in Fig 8 . As expected, we observed smaller bubbles, therefore increasing interfacial areas, as the rotation speed increased. From our observation, the bubbles were smallest at the edge of the disk and increased in size as the flow moved closer to the exit of the reactor. This can also be expected since the shear forces are the highest at the rim of the rotating disk. Analysis of these bubble sizes with a high-speed camera resulted in histograms which we used to better understand how the average interfacial area was changing with the rotation speed (Fig ). As expected, with increasing rotation speed we saw an increase in interfacial area. At high, RPMs, however, the analysis suggests a plateau of the bubble sizes. This is most likely due to the inability of the camera/MATLAB to observe bubble size less than 0.2 mm, which compares to 5 pixels in the images. Nevertheless, the theoretical bubble size, which is obtained from Eq.1 , could be matched to the obtained sizes up to 2000 RPM. In this equation, derived from the correlation between the energy dissipation and mass transfer coefficient; h represents the gap distance and V r the reactor volume therefore, we can say with reasonable certainty that the theoretical trend should also be followed up to 3000 RPM. This implies that the specific interfacial area in the reactor at 3000 RPM was approximately 1000 m 2 /m 3 . More illustrations and videos of the gas-liquid characteristics are presented in Supporting Information. In the pRS-SDR, energy is required to rotate the disk, which increases the overall energy requirements of the system. The energy dissipation with rotation speed can be estimated from the correlation of de Beer et al. , presented in Eq. 2, where G represents the gap ratio and Re ω , the rotational Reynolds number. From this analysis (Fig 10 ), we can see that the excess energy taken for mixing will only account for a fraction of the light source. For our system, where we seem to reach kinetic limitations around 2000 RPM, the energy dissipation is approximately 15 W, which is 11% of the total energy consumption when taking the 120 W rated light source into account. Therefore, in a photochemical process the light source will most likely be the source of the highest energy consumption. (2)