Transport of vanadium(V) through a tricaprylylmethylammonium solid supported liquid membrane from aqueous acetic acid/acetate solutions

A liquid membrane system for vanadium transport has been designed by using tricaprylylmethylammonium chloride (Aliquat 336®) dissolved in isopropylbenzene (cumene) or dodecane as carrier. The work has been undertaken by first determining the liquid-liquid distribution of vanadium(V) between aqueous solutions of different acidity and an organic solution containing the carrier. Optimum conditions for both extraction (4<pH<7) and stripping (8<pH<13) were established. Both cumene and dodecane carrier solutions provided similar distribution data. These conditions were implemented for the transport of vanadium(V) through the laminar supported liquid membrane. Transport experiments were carried out at low vanadium(V) concentration (ppm level). The study of the liquid membrane included the influence of hydrodynamic and chemical conditions, i.e., stirring speed, organic solvent, carrier concentration, ionic strength and pH of the aqueous phases. Dodecane membranes provided higher transport of vanadium(V) than cumene membranes. Dodecanol, ranging from 0 to 10% (v/v), was added to the dodecane solution of Aliquat 336® to enhance its solubility. The effect of acidity of the feed solution on vanadium transport showed a similar behaviour to that obtained for the liquid-liquid distribution studies. On the contrary, selectivity properties of the liquid membrane showed clear differences with the corresponding data of solvent extraction, i.e., molybdate extracted by Aliquat 336® was not transported through the liquid membrane. The results obtained in both batch distribution experiments and dynamic membrane transport indicated that vanadium(V) was extracted by means of metavanadate chemical species. © 1995.