Effects of bubble size on mass transfer in two-phase nondispersing liquid-liquid contactors using bubble agitation

Mass transfer rates of an electrolyte through an aqueous film in bubble agitated two-phase nondispersing liquid-liquid square contactor were measured using an aqueous electrolyte (buffer) solution as the light phase and mercury as the heavy phase. The mass transfer data were correlated by the equation N_Sh = 22.666 N_Re^0.520 N_Sc^0.502.

The mass transfer rates were measured polarographically via the diffusion limited, electrically driven reduction of the quinone at the mercury surface in a square contactor. Confirmation of the bubble diameter was done to verify the equation to be used in correlation of the mass transfer data. The bubble diameter was determined from a static force balance. The variables tested were gas flow rate, cell size, orifice diameter, and various physical properties of the aqueous phase.

The parameters having the most significant effect on mass transfer rates were aqueous phase viscosity, gas flow rate, and orifice diameter. A correlation presented in the literature is similar to the correlation developed here except that in this study the bubble diameter was the characteristic length in the Reynold's number. The correlation developed here covers a wider range of gas flow rates than previously found in the literature.