Synthesis and characterization of a novel nanocomposite ([(SBA-15)-(Cu(BTC)]-[KZn(Fe(CN)6)]) for cesium removal from aqueous media and optimization condition using central composite design

Abstract

This research aimed to remove cesium ions (Cs+) from aqueous solutions using a new synthetic nanocomposite [(SBA-15)-Cu(BTC)]-[KZn Fe(CN)6)]. To this end, a metal-organic framework [Cu(BTC)] was combined with silica (SBA-15) to improve its properties. This porous structure was employed as the support to immobilize [KZn(Fe(CN)6)] ion exchanger on its surface. The physical and chemical properties of the synthesized compounds were characterized. The response surface methodology (RSM) based on central composite design (CCD) was used to determine optimal operating conditions and interaction effects of the parameters influencing Cs adsorption. The optimal operating conditions were determined based on the ANOVA results (C = 200 mg/L, t = 1 h, T = 60 °C, and pH = 5.4). The kinetic and isotherm studies were carried out, and the thermodynamic properties of the system were investigated. The experimental kinetic data fitted well with the Elovich kinetic model. The Temkin isotherm suitably described equilibrium adsorption condition. The maximum equilibrium adsorption capacity was 115 mg g−1, and the experiment reached equilibrium whit in 1 h. The thermodynamic properties suggested that Cs adsorption was endothermic, spontaneous, and accompanied by an increase in the system's randomness. The presence of K+, Na+, and Sr2+ ions did not affect Cs adsorption. Finally, the experiments on adsorbent recovery showed that the adsorbent could be used with desirable results for three cycles. The eco-friendly nanocomposite presented in this research is suggested as an efficient adsorbent for Cs removal from aqueous solutions.