Selective adsorption of potassium and rubidium by metal–organic frameworks supported supramolecular materials

A new MOFs-based adsorbent UiO-66@iPCC5 was prepared by hybridization of 25,27-bis(iso-propoxyl)-calix[4]arene-26,28-crown-5 (iPCC5) into the pores of UiO-66, one of the Zr-MOFs. The adsorption of K and Rb onto UiO-66@iPCC5 from 0.4 to 6.0 M HNO3 was studied. UiO-66@iPCC5 showed strong adsorption ability and selectivity for K and Rb over others. The removal efficiency was 98.19% for K and 98.25% for Rb. The adsorption mechanism was discussed by XPS and EDS. The adsorption isotherms of K and Rb well fitted with Langmuir model. The thermodynamics and kinetics of K and Rb adsorption onto UiO-66@iPCC5 were investigated.