Flooding characteristics of aqueous two-phase systems in a countercurrent sieve-plate column

The hydraulic capacity of countercurrent liquid-liquid extractors is constr ained by its flooding characteristics. This study presents flooding data fo r aqueous two-phase systems containing PEG 4000 and Na2SO4 at various conce ntrations in a countercurrently operated sieve-plate column in the absence of solutes. Flooding limits, average droplet sizes and dispersed phase hold -ups at flooding conditions were measured as well as densities, interfacial tensions and viscosities. A correlation proposed by Richardson and Zaki (T rans IChemE 32:35-53 (1954)) was used successfully for the description of t he slip velocities and thus maximum column throughputs. (C) 1999 Society of Chemical Industry.