Cs+ removal and optical detection by microporous lanthanide silicate Eu-AV-20 in a fixed-bed column

Abstract

Microporous silicate Eu-AV-20 has recently proved to be a promising ion exchange material for cesium removal from aqueous solutions, and its potential for Cs+ photoluminescence sensing was additionally demonstrated. In this work, Cs+ removal was performed in a fixed-bed column, and the influence of linear velocity and mass of ion exchanger on the breakthrough curves was analysed. The experimental data were modelled on the basis of Nernst–Planck (NP) equations and with four well-known analytic models. The analytic expressions provided low errors (root mean square deviation, RMSD, between 3.20% and 6.47%); the 2-parameter NP-based model fitted the data quite well (RMSD=6.66% for correlation and 6.54% for prediction), yielding crucial information on both the transport mechanism within the Eu-AV-20 particles, and the intrinsic dynamic behaviour of the fixed-bed ion exchange column. Taking into account that Eu-AV-20 samples loaded with different amounts of Cs+ exhibited distinct photoluminescence spectra, our results reinforce the potential of AV-20 materials for Cs+ sensing, which raises the possibility of online monitoring the ion exchange in a fixed-bed column using an optical fibre and a spectrometer.