Fixed bed removal of Cs+ from aqueous solutions by microporous silicate ETS 4: Measurement and modeling of loading regeneration cycles
Abstract ETS 4 was prepared by hydrothermal synthesis and characterized by powder X ray diffraction in order to assess its ion exchange capacity towards the removal of Cs+ from aqueous solutions in both batch and fixed bed operation modes. Several assays were carried out to measure isotherm (8 experiments) and breakthrough curves (5 experiments) a set of loading regeneration loading experiments was also performed highlighting the ability of ETS 4 to be used in cyclic ion exchange. Powder X ray diffraction showed that parent and Cs+ exchanged ETS 4 are isostructural. The Langmuir equation achieved good correlation results (average deviation of 6.58% while the Nernst Planck based model proposed for the fixed bed assays fitted one breakthrough curve with 18.66% error, and was able to predict the remaining four experiments with 9.55% error. The Nernst Planck parameters are the self diffusion coefficients of Cs+ and Na+ in ETS 4, whose values D Cs 3.193 x 10 16 m 2 s 1 and D Na 6.088 x 10 15 m 2 s 1 are consistent with the microporosity of ETS 4 framework and with the size of the counter ions.