Effect of impinging angles of liquid–liquid distributor on the extraction and mass transfer performance in a rotating packed bed

Liquid-liquid extraction is a typical separation process that is widely used in various chemical processes. However, the effect of two-liquid feeding mode on the liquid–liquid Murphree efficiency ( E ) of rotating packed bed (RPB) remains unclear, limiting its applications. In this work, liquid–liquid distributor with different impinging angles (2 θ ) of two feeding liquid jets in the RPB was designed to evaluate the E , taking water as the extractant to extract benzoic acid from kerosene into the aqueous phase. The effects of operating conditions such as the 2 θ , high gravity level ( β ), and liquid initial velocity ( u 0 ) on the E and overall volumetric mass transfer coefficient ( K L a ) of the RPB were studied. Experimental results revealed that both E and K L a increased with the increase of 2 θ , β , and u 0 . In particular, when 2 θ  = 90°, E and K L a exhibit optimal values. At β  = 49.25, u 0  = 1.75 m/s, and 2 θ  = 90°, since the average diameter of the daughter droplets was smaller and the effective mass transfer area was larger, E reached a maximum of 64.7 % and K L a was 0.489 s −1 . A correlation for predicting K L a has been established, with deviations falling within ± 20 %. This work provides theoretical basis for guiding the enhancement of mass transfer in liquid–liquid systems.