Synergistic interaction between organophosphorus extractants for facilitated lanthanum transport through supported liquid membrane

Abstract The development of the membrane process is an effective strategy that increases the efficiency of separation processes. Extraction of lanthanum in the category of rare earth elements with the supported liquid membrane was examined in a laboratory system by studying the synergistic effects of organophosphorus extractants. The experimental design technique (CCD approach) was used in two steps to optimize the results. In the first step, the concentrations of the organophosphorus extractants (mixtures of D2EHPA, TBP and TOPO), and in the second step, secondary parameters such as the amount of ions present in the aqueous solution, the acidity concentration of feed phase and stripping solution were optimized to reach the maximum permeability coefficient through the membrane. The optimum conditions for TOPO, TBP, and D2EHPA extractant concentration, pH of the feed solution, La(III) ion concentration, and HNO3 stripping phase were obtained equal to 0.1 M, 0.3 M, 0.8 M, 5.2, 200 ppm, and 2 M, respectively. The extraction and stripping efficiencies in optimum condition are obtained equal to 56.89, and 49.88%, respectively. The correlation coefficient equal to 0.96 and 0.94 in both steps showed the validity of models to predict permeability coefficient for lanthanum extraction.