STABILIZATION OF SUPPORTED LIQUID MEMBRANES BY INTERFACIAL POLYMERIZATION TOP LAYERS

In this paper, a new method of stabilizing supported liquid membranes ii; presented. The stabilization is based on the application of polyme ric top layers to the surface of microfiltration membranes, preventing loss of the liquid membrane phase out of the support pores. The modif ied microfiltration membranes were used as supports for supported liqu id membranes and tested on selective nitrate transport and stability. Screening experiments revealed that most applied top layers did not hi nder the transport of nitrate ions. However, a few were able to improv e the stability of the liquid membranes. Best results were obtained wh en piperazine (PIPA) and trimesoyl chloride (TMCl) were used as monome rs. For Accurel polypropylene supports with PTPA/TMCl top layer, nitra te flux was constant at the initial 18 z: 10(-10) mol cm(-2) s(-1) for 350 h of simulated operation. For uncoated supported liquid membranes (SLMs), the flux decreased within one day from 18 x 10(-10) to almost 0 mol cm(-2) s(-1). Scanning electron microscopy investigations revea led a particular, rippled surface texture of layers prepared with thes e monomers. (C) 1998 Elsevier Science B.V.