Backscattering spectrometry studies on metal ion distribution in polymer inclusion membranes

Abstract

Polymer inclusion membranes based on cellulose triacetate polymer, containing 2-nitrophenyloctyl ether as plasticizer and dinonyl napthalene sulfonic acid as cation exchanger were loaded with Cs⁺ and Ag⁺ and were studied by backscattering spectrometry technique to measure the distribution of the metal ions across the membrane using a proton beam. The study showed that the distribution of the metal ions across the membrane is uniform, thereby suggesting the uniform distribution of the cation exchanger. This indicates that the hydrophilic nature of the sulfonic acid group in the cation exchanger does not significantly influence its distribution in the predominantly hydrophobic matrix of cellulose triacetate. However, the microstructure of the membrane, obtained by atomic force microscopy, shows the formation of blobs on the surface of the PIM indicating the inhomogeneity at the sub-micron scale.