Pb Separation from Aqueous Media through a Liquid Membrane Process

Gheorghe, Emil; Barbu, Luminita; Luca, Constantin

Emil Gheorghe, Luminita Barbu, Constantin Luca

Pb Separation from Aqueous Media through a Liquid Membrane Process

Abstract:

This work presents two versions of the Pb2+ separation method from aqueous phases through a membrane separation process with a liquid membrane of chloroform. The selectivity for Pb2+, in both ways, results from the presence in the membrane of macrocycle carrier benzo 18-crown-6. In the first one, yields higher than 90% are assured through coupling with the co-transported picrate anion involved in proton transfer process which provides the necessary energy for a pH gradient active transport mechanism. This mechanism requires a high acidity level of the aqueous receiving phase (pH =2). In the second version, which is based on the same membrane system, we use P2O74- anion as a complexing agent in the receiving phase, but the anion doesn’t disturb the transport mechanism and the yield at pH = 2 in receiving phase; at pH =11 the mechanism is completely changed and the yield tends to 90% again. The pyrophosphate anion has a high complexing effect for Pb2+ and the complex formed at the membrane-receiving phase interface diffuses in the receiving phase. In both versions, the transport of Pb2+ is an active process and it takes place in a reversed way versus the concentration gradient. It is important to note that Cd2+ is characterized by a very small transport yield, in comparison with Pb2+ which is weakly complexed by both carriers benzo 18-crown-6 and pyrophosphate anion. Both versions of this lead separation method are carried out in a double jet liquid membrane set-up which permits to operate in continuous working conditions.

Keywords:
membrane separation; liquid membrane; macrocycle carrier; benzo 18-crown-6; Pb2+; Cd2+; pyrophosphate anion

Issue: 2008, Volume 59, Issue 3

Pages: 277-282

Publication date: 2008/4/9

https://doi.org/10.37358/RC.08.3.1748

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This article is published under the Creative Commons Attribution 4.0 International License

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