Selective pertraction of Pd(II) across a solid supported liquid membrane using thiamacrocycle S-6-pentano-36 as an ionophore

Thiamacrocycle-facilitated co-transport of Pd(II) from dilute nitrate acidic solutions has been examined across solid supported liquid membrane (SSLM) deploying S-6-P-36 as the novel ionosphere. Under the optimum conditions, micro amounts of palladium could be effectively transported from a feed (1 M HNO3) solution across an organic thiacrown membrane into the product side containing strippants like 2 M NH4SCN. Its concentration in the source phase decreased as [Pd](f,t)=[Pd](f,o) exp(-K-obs t). The apparent rate constant (K-obs) increased with increasing carrier concentration and became nearly constant above 0.02 M S-6-Pentano-36. With increase in nitric acid concentration from 0.1 to 5 M HNO3, K-obs decreased. A polytetrafluorethylene thin film support coded as TE-35 and toluene as membrane solvent were invariably used. Among the several reagents tested, ammonium thiocyanate served most efficiently as the strippant. More than 95% of palladium could be readily transported from diverse matrices through 0.05 S-6-Pentano-36 into dilute aqueous ammonium thiocyanate strippant in about 6-7 h.