Sorption of electrochemically generated V(IV) on a Cation Exchanger and its Separation from W

The sorption of V(IV) onto a strong cation exchanger was investigated from a solutions containing sodium cations and tungsten. V(V) was reduced to V(IV) on a carbon felt cathode at a constant potential of -1500 mV vs. Ag/AgCl. V(IV) was completely captured by the cation exchanger in presence of Na+ ions. The breakthrough capacity was 0.63 mol vanadium/L. In presence of W, a high leakage of V(IV) occurred. Formation of mixed V(IV)/W heteropolyanions is considered. W was not taken up by the cation exchanger. V(IV) was released from the cation exchanger with 1 M HCl within 15 BV and a concentrated solution of average 2.2 g vanadium/L was obtained.