Selective exchange of alkali metal ions on EAB zeolite

EAB zeolite was successfully prepared and applied to selective adsorption of Li', Na' and K' ions. The physical and chemical properties of the adsorbent were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope (SEM) and thermogravimetry (TG) methods. The ion exchange behaviours for Li', Na' and K' ions in monomcomponent and multicomponent solutions were studied. In independent ion exchange, the ion exchange capacities ratios a(Na/Li) and a(K/Li) were 3.8 and 6.2, respectively. In competitive ion exchange, the selectivities b(Na/Li) and b(K/Li) increased with the initial concentrations and reached 409 and 992 when the initial concentrations was 100 mmol/L. The thermodynamic study results showed that Gibbs free energy change (DGH) of ion exchange reaction between Li-EAB and K' was-34.96 kJ/mol, indicating that ion exchange of K' ions was more energetically favourable than Li' ions. The calculation results showed that the energy barriers of ion exchange increased in the order K' < Na' < Li'. The study shows that EAB zeolite is potential to be used in the sep-aration of alkali ions. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.