Investigation of mass transfer and hydrodynamics of liquid-liquid extraction in spinning disc reactor by computational fluid dynamics simulation

This research investigated the mass transfer performance of the extraction of benzoic acid in water/n-heptane system in a spinning disc reactor (SDR). The effects of rotational disc speed (R), volumetric flow rate (Q) and disc surface on the liquid flow pattern, extraction efficiency (E) and overall mass transfer coefficient (kLa) were studied. Three disc surface types were considered including 1) smooth disc, 2) roughness A disc (metal sandpaper P36), and 3) roughness B disc (metal sandpaper P24). The highest values of E and kLa were 69.7% and 9.59 s-1 when using the roughness B disc surface operated at R of 1000 rpm and Q of 5 mL/s. A 3D-multiphase CFD model was applied to investigate the hydrodynamic characteristics in the SDR for further understanding of the mass transfer performance in the SDR. The dissipation rate (epsilon) and micromixing time (tm) were proposed to compare the turbulent degree of each disc surface. The mass transfer performance was significantly enhanced by using the metal sandpaper as the disc surface. In addition, the metal sandpaper disc surface has a great ability to reduce energy consumption in comparison with the smooth disc surface.