STABILITY OF SUPPORTED LIQUID MEMBRANES CONTAINING LONG-CHAIN ALIPHATIC-AMINES AS CARRIERS

The stability of liquid membranes containing as carriers three different commercially available long-chain aliphatic amines, Primene JM-T (primary), Amberlite LA-2 (secondary) and trilaurylamine (TLA, tertiary) has been investigated in experiments where the feed solution was synthetic Hanford site groundwater, the strip solution was 1 M NaOH and n-dodecane was the diluent. By using flat-sheet supports the following order of stability was measured: tertiary > secondary > primary. This is the reverse order of the interfacial tension lowering at a water-n-dodecane interface. The water solubility of the amines also seems to play an important role in determining the membrane stability. Experiments performed with much thicker hollowfiber supports have shown that a larger inventory of organic phase absorbed in the membrane pores ensures a remarkably higher membrane stability. The secondary amine provides the best overall performance and is the carrier of choice for a SLM process for groundwater decontamination from anionic species. Possible alternative uses of the primary and tertiary amines for the same decontamination process are also discussed.