Highly selective adsorption of radioactive cesium by novel calix[4]biscrown-6 functionalized millimetre-sized hierarchically porous carbon spheres

Abstract

The efficient removal of Cs(I) from high-level liquid wastewaters (HLLW) is vital to the environmental remediation and development of nuclear energy. Herein, the novel millimeter-sized carbon-based supramolecular recognition material (C4BisC6/MMCs-P) were designed and constructed by coating polystyrene-divinylbenzene onto millimeter-sized hierarchically porous carbon spheres as matrix immobilization of calix[4]biscrown-6 (C4BisC6). The unique structure endows C4BisC6/MMCs-P with millimeter-sized, convenient recycling, and high selective adsorption capacity for Cs(I). The C4BisC6/MMCs-P-5 (where the weight percent of C4BisC6 was 28.4 %) achieved the greatest distribution coefficient of Cs(I) (225.79 mL·g−1), which is almost nine times higher than that of C4BisC6/MMCs. The optimal adsorption acidity was 3.0 mol∙L-1 HNO3 that was similar acidity of common HLLW. The maximum adsorption capacity of Cs(I) by C4BisC6/MMCs-P-5 was 22.72 mg·g−1, surpassing to most currently-reported adsorbents. Meanwhile, C4BisC6/MMCs-P-5 showed high selectivity for Cs(I) competing with cations (Rb+, K+, Na+, Sr2+ and Ba2+). This work paves an efficient strategy for separation of Cs(I) from HLLW by ingeniously designing a supramolecular recognition material C4BisC6/MMCs-P-5 to address environmental contamination issue.