Adsorption of cesium using supermolecular impregnated XAD-7 composite: isotherms,kinetics and thermodynamics

As an effective cesium complex agent, calix[4]biscrown-6 (CBC) applied at a low cost way is of interest. In this study, CBC/XAD-7 was prepared by embedding CBC into XAD-7. Subsequently the as-prepared sorbent was used for the removal of cesium from aqueous solution as functions of HNO₃ concentration, contact time, temperature and initial cesium concentration. The results revealed that the nitric concentration influenced cesium adsorption by complex and protonation interaction. The most effective adsorption happened at the nitric concentration of 1.0 M. The adsorption isotherm well described with the Langmuir model illustrated a monolayer adsorption. Its maximum adsorption capacity was 24.4 mg/g in the 2 M nitric acid aqueous solution. The adsorption kinetics was in accordance with the pseudo-second order model, which indicated a chemisorption. The thermodynamic parameters demonstrated that the adsorption process was exothermal and spontaneous. In addition CBC/XAD-7 showed highly selective recognition toward cesium and good reusability. The study offered an economical and effective material for cesium removal.