University of Khartoum

Nafion-117 Stability And Behavior During Electrodialysis Of Conc Entrated Chromic Acid Containing Metallic Impurities

Nafion-117 Stability And Behavior During Electrodialysis Of Conc Entrated Chromic Acid Containing Metallic Impurities

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Title: Nafion-117 Stability And Behavior During Electrodialysis Of Conc Entrated Chromic Acid Containing Metallic Impurities
Author: I.Ahmed, M. Elmuntasir
Abstract: In this paper Nafion-117 ® ion-exchange membrane stability and behavior during use in an experimental cell to regenerate hard chrome plating solutions, and thus prevent pollution fr om their disposal practices, is investigated and assessed using various experimental techniques. Nafion was found to withstand the highly acidic environment of such solutions(pH≈1) with only minor rotations in the fluorocarbon backbone due to accommodation of anionic chromic acid species within its clusters. The ion- exchange selective behavior was found to suffer minor reduction and the transport resistance to metallic cations was found to be solely due to reduction in the volume of ion clusters of fixed charge sites which result from reduced water uptake and reduced ion solvation energies inside the membrane pores. While porposity was found to increase by 25%, the water content decreased by 10% when Nafion was removed from water into contaminated hard chrome plating solutions resulting in a reduced pore size (3.2 nm). The transport selectivity and tortuosity of cations was found to correlate with valence and ionic radius resulting in a selective uptake in the order + + + + ≥ ≥ ≥ Cu Ni Fe C
URI: http://hdl.handle.net/123456789/6589
Date: 2006-09


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