Effect of quaternary ammonium salts on carrier-mediated transport of lanthanide ions through cellulose triacetate membranes

Fluxes of all lanthanides, except promethium, across cellulose triacetate membranes were determined by using mixtures of o-nitrophenyl n-octyl ether and quaternary ammonium salts as plasticizers, and 4-benzoyl-3-methyl-1-phenyl-5-pyrazolone (BMPP) and 4-trifluoroacetyl-3-methyl-1-phenyl-5-pyrazolone (TMPP) as carriers. The quaternary ammonium salts used were didodecyldimethyl-, distearyldimethyl-, tetrahexyl-, tetraoctyl-, and tetradecylammonium bromides [referred to as (C12)2NBr, (C18)2NBr, (C6)4NBr, (C8)4NBr, and (C10)4NBr, respectively]. The effect of these ammonium bromides on the flux was demonstrated. For membranes containing 0.1 M (C12)2NBr and (C18)2NBr, BMPP exhibited considerably high fluxes. The fluxes of lanthanum and cerium using BMPP for (C12)2NBr were higher than those of the other lanthanides. For the membranes containing 0.5 M (C12)2NBr and 0.1 M (C18)2NBr, however, no difference in flux among the lanthanides was observed. The fluxes using TMPP for (C12)2NBr and (C18)2NBr were very small, with the exception of some lanthanides. Appreciably high fluxes were observed for membranes containing 0.1 M (C6)4NBr using BMPP. For (C8)4NBr and (C10)4NBr, BMPP exhibited low fluxes. For these membranes using TMPP, the lanthanides were scarcely transported. 13 refs., 5 figs., 2 tabs