Elimination of Cs⁺ from aquatic systems by an adsorbent prepared by immobilization of potassium copper hexacyanoferrate on the SBA-15 surface: kinetic, thermodynamic, and isotherm studies

For elimination of cesium from aqueous solutions, mesoporous SBA-15 was synthesized and employed as the support for immobilization of potassium copper hexacyanoferrate. The synthesized adsorbent was characterized by various techniques and was used for adsorption of cesium. The results indicated that its adsorption capacity was 174.80 mg/g and superior to many studied adsorbents. The adsorbent represented good selectivity in the presence of some studied co-existing. The Temkin, Redlich–Peterson, Sips, Langmuir, and Freundlich isotherm models were used to evaluate the experimental data. The error analysis performed by EABS, ERRSQ, and HYBRID methods showed that the data was in good agreement with the Langmuir model indicating that the process was monoenergetic and the uptake of cesium forwarded through monolayer process. The pseudo-second-order model was recognized as the adequate model to describe the kinetic data of the adsorption process. The adsorption process was endothermic and spontaneous. The regeneration tests revealed that the adsorbent retained most of initial capacity after recovery.