A thermo-sensitive polymer network crosslinked by Prussian blue nanocrystals for cesium adsorption from aqueous solution with large capacity

Abstract

For human health and safety, it is of great importance to develop novel materials with large capacity for efficient removal of radioactive cesium from aqueous solutions. We report herein a strategy for effective adsorption of cesium from aqueous solution by using a Prussian blue nanocrystal-crosslinked thermo-sensitive polymer network. Specifically, the thermo-sensitive copolymer, poly(pentacyano(4-vinyl pyridine)ferrate-co-sulfobetaine methacrylate), is synthesized by radical copolymerization, and then Fe³⁺ is added to crosslink the copolymer to obtain PB-PSBMA for cesium adsorption. Above the upper critical solution temperature, there is an enhanced effect on the adsorption efficiency. The polymer network prevents agglomeration of Prussian blue nanocrystals and maintains an effective surface area, which facilitates adsorption and leads to a remarkably large capacity of 465.1 mg g⁻¹. A similar concept could be applicable to enhance adsorption in other system: the synergistic effect of thermo-sensitive properties and thermodynamic behavior can enhance the adsorption. The adsorption process kinetically followed a pseudo-second-order model with high selectivity. PB-PSBMA can be regenerated and reused with high adsorption efficiency. Importantly, for the first time it is found that cesium ions can be bound with cyano groups and trapped in PB crystal lattice spaces. This work indicates that PB-PSBMA is a promising adsorbent to realize effective removal of cesium ions from aqueous solutions.