Use Of Supported Liquid Membranes Research Articles

A study on Neodymium recovery from aqueous solutions for designing a new generation of sandwich liquid membrane

Liquid Membrane (LM) based processes, as Supported Liquid Membranes (SLMs), have been proposed, for over 30 years, as effective methods for the selective separation of inorganic/organic species from different water streams. The industrial use of SLMs has been limited mainly by their insufcient stability. To investigate on the main cause of system destabilization and the optimal conditions for mass transport, a good reference system is the traditional SLM. To this aim the recovery of neodymium (Nd) from acidic media by a traditional SLM has been studied, giving particular attention to permeation and stability. The results clearly evidenced that system stability was strongly influenced by the solubilization of the carrier in the aqueous phases. The consideration and the experimental results reported in this work give useful information to shift the next research step versus the development of a 2nd generation of SwLM able to give satisfactory system performance in view of industrial application, such as Nd as well as rare earth elements or salt recovery from aqueous media.

Separation of nickel(II) and cadmium(II) ions with ion-exchange and membrane processes

ABSTRACTSeparation of nickel(II) and cadmium(II) ions with use of ion-exchange resins—Amberlyst 15 and Lewatit OC 1026—supported liquid membranes (SLM), polymer inclusion membranes (PIM) and ion-exchange membranes (IM) from sulphate solution has been studied. Di(2-ethylhexyl) phosphoric acid (D2EHPA) was used as the ion-carrier in PIM and SLM separation. It was shown that use of SLM or PIM membranes enables separation of Ni(II)/Cd(II) ions. Experimental results data show that the highest recovery factor values were obtained for supported liquid membranes. The SEM surface and cross-sectional images of SLM support, polymer inclusion membrane and ion-exchange membrane have been also prepared.

Stability and Selectivity of Supported Liquid Membranes with Ionic Liquids for the Separation of Organic Liquids by Vapor Permeation

The stability of supported liquid membranes (SLMs) was partially improved by using a room-temperature ionic liquid (RTIL) as the membrane liquid and by employing a vapor permeation process for the separation of toluene/cyclohexane systems and the dehydration of aqueous 1-propanol and aqueous ethanol mixtures. Because the basic characteristics of RTILs are that they have high surface tension and no detectable vapor pressure, the loss of membrane liquid by evaporation was avoided completely. The separation of toluene/cyclohexane mixtures was conducted for as long as 550 h, and the separation factor was kept within the range of 15−25, with the membrane showing good durability in vapor permeation. The use of SLMs with ionic liquids was shown to be a promising method for separating organic/organic and organic/water mixtures.