TRANSPORT OF GOLD ION FROM A HYDROCHLORIC-ACID SOLUTION ACROSS A SUPPORTED LIQUID MEMBRANE CONTAINING SULFIDE PODAND

The transport of gold ions (5X10(-5) M) from a diluted hydrochloric ac id solution to a stripping solution across a supported liquid membrane (SLM) containing 0.1 M solution of polydentate neutral sulfide podand 1,12-di-2-thienyl-2,5,8,11-tetrathiadodecane (TTD) in m-chlorotoluene was studied. The rate of transport of gold ions increased in the sequ ence of the stripping solutions, NaBr much less than NH3, thiourea<NaS CN<NaI<thiosulfate. Among three microporous polymers used, the rate wi th Celgard 2500 membrane is ca. 23% higher than for Celgard 4510 or 25 02. The present result shows that the selectivity for gold ion is good against copper, zinc and iron ions present in 200:1 excess. The gold flux (J) increases almost linearly with an increase in the initial gol d concentration over the range 10(-5) - 10(-4) M; for 5X10(-5) M Au it is equal to 10.3X10(-8) mol cm(-2) h(-1).