Journal of Membrane Science, Vol.164, No.1-2, 229-240, 2000
Comparison of liquid membrane processes for the removal of cadmium from wet phosphoric acid
The viability of the cadmium removal from wet phosphoric acid by means of three liquid membrane processes (emulsion liquid membranes, supported liquid membranes and non-dispersive solvent extraction) has been demonstrated in previous works where the kinetics of cadmium removal were successfully studied [A.I. Alonso, A.M. Urtiaga, S. Zamacona, A. Irabien, I. Ortiz, J. Membr. Sci. 130 (1997) 193; J.A. Daoud, S.A. El-Reefy, H.E Aly, Sep. Sci. Technol. 33 (1998) 537; T Gallego, E.S. Perez de Ortiz, Separation of cadmium from phosphoric acid containing Cu2+ and Cd2+ using surfactant liquid membranes, in: D.M. Maron, Begell (Ed.), Int. Symp. on Liquid-Liquid Two Phase Flow and Transport Phenomena, Antalya, Turkey, 3-7 November 1997, Begell House, New York, 1998, pp. 301-310]. This work has been focused on the comparison of the three liquid membrane technologies for the removal of Cd, working with cadmium initial concentrations in the range of 1.8 x 10(-4)-4.45 x 10(-3) M and using Cyanex 302 as organic extractant in the concentration range 0.025-0.63 M. The comparison has been made in terms of the values of mass transfer flux. The mass transfer models and the corresponding mass transport parameters provided the system tools for the quantitative comparison. By simulation of the cadmium flux and of the evolution of the cadmium concentration with time it was concluded that the rate of Cd removal and the values of mass transfer flux under the studied conditions varied in the order NDSX > ELM > SLM. (C) 2000 Elsevier Science B.V. All rights reserved.