MEMBRANE MASS-TRANSPORT COEFFICIENT FOR THE RECOVERY OF CR(VI) IN HOLLOW-FIBER EXTRACTION AND BACK-EXTRACTION MODULES

This work has been focused to the determination of the membrane mass t ransport coefficient in the simultaneous non-dispersive extraction and back-extraction of Cr(VI). Following the methodology previously repor ted by the authors for the kinetic modelling of hollow fiber extractio n and back-extraction processes, considering the assumption that the o verall mass transport resistance is dominated by the resistance in the organic membrane, when Aliquat 336 is used as carrier. and after the description of the interfacial chemical equilibrium in the extraction process (non-Linear model, K-eq = 0.35) and in the back-extraction pro cess (linear model, H-r = 3.6), it has been possible to describe succe ssfully the experimental results obtaining the optimum value for the m embrane mass transport coefficient, K-M = 2.2 X 10(-8) m/s, which allo ws the design and optimization of the recovery of Cr(VI).