Solid-liquid mass transfer at the walls of a rectangular agitated vessel

Rates of mass transfer between the walls of a rectangular agitated vessel and solution were studied by measuring the limiting current of the cathodic reduction of ferricyanide ion at the vessel wall. Variables studied were rotation speed of 45 degrees pitched blade turbine impeller, physical properties of the solution and the presence of drag reducing polymer in the solution (Polyox WSR-301). The data were correlated for polymer free solution by the equation: Sh = 1.925 Sc-0.33 Re-0.5 Comparison of the present data with previous heat and mass transfer studies conducted in cylindrical vessels has shown that the mass transfer behaviour of agitated rectangular vessels lie between baffled and unbaffled agitated cylindrical vessels. Polyox addition was found to reduce the mass transfer coefficient by an amount ranging from 5.6 to 37% depending on polymer concentration. Practical implications of using drag reducing polymers in agitated vessels were discussed.