Metallic ions extraction and transport in supported liquid membrane using organo-phosphoric compounds as mobile carriers

The extraction and transport of cadmium (II) and lead (II) in supported liquid membrane (SLM) using tributylphosphate (TBP), tris-ethylhexyl phosphate (TEHP), trioctylphosphine oxide (TOPO) and di-2-ethlylhexyl phosphoric acid (D2EHPA) as mobile carriers was studied. The liquid–liquid extraction tests showed a maximum distribution coefficient when the carrier concentration was greater than 10−3 M. In transport experiments the transmembrane flux increased with increasing carrier concentration reaching a limiting value (∼5 × 10−10 mol cm−2 s−1) at greater than 10−3 M concentration. An impregnation time of 1 h of the support in the organic phase is necessary for giving a good efficiency to the supported liquid membrane (SLM). The other fundamental parameters optimum (carrier concentration, metal concentration and support characteristics) were determined. The permeability was significantly higher using Celgard 2400 support with respect to Celgard 5550, 3401, 2500 and 2402. A comparative study of the transport across such a membrane containing TBP, TEHP, TOPO or D2EHPA has shown that the cadmium (II) and lead (II) transport efficiency was decreased using a mixture of D2EHPA with other carriers.