The influence of viscosity on the liquid-phase mass transfer resistance in packed columns

The correlations available in the literature cannot be used to est. the liq.-phase mass-transfer coeff. (kL) for viscous solns. Even correlations that agree for water-like viscosities diverge by an order of magnitude for viscosities of only 10 mPa-s. Here, kL (kLa) measurements are given that are performed by stripping O from aq. solns. in a column of 0.3-m diam. filled with 0.025-m glass Raschig rings. The viscosity is varied by varying the amt. of Na alginate, glycerol, or polyethylene glycol in the water. The viscosity not only has an effect on the diffusivity of the absorbed gas (this highlights the importance of accurate diffusivity estns., both for data interpretation and for design work), but also has an addnl. net effect such that kLa/D1/2 (D = diffusivity of solute in liq.) decreases in approx. inverse proportion to the square root of the viscosity. [on SciFinder (R)