Interconnected superporous adsorbent prepared via yeast-based Pickering HIPEs for high-efficiency adsorption of Rb+, Cs+ and Sr2+

Abstract

High internal phase emulsions (HIPEs) template method is an emerging effective method of fabricating high-efficiency, orderly porous polymer adsorbents, but the conventional HIPEs template requires harmful surfactants, so the development of surfactant-free green emulsion templates become the subject of great significance. Herein, we prepared a green surfactant-free oil-in-water (O/W) Pickering HIPEs stabilized solely with non-toxic caustic-pretreated yeast (P-Yeast), and used it as template to prepare a novel adsorbent (P-Yeast-PAA) with interconnected superporous structure by a one-step solution polymerization of acrylic acid (AA) monomers in the emulsion. Interestingly, the surfactant-free Pickering-HIPEs exhibited superior stability due to the fine affinity between P-Yeast and AA monomer, and the pore structure of the adsorbent can be easily regulated by changing the contents of the monomer or the particles used for stabilizing the emulsion. In addition, the adsorbents prepared from P-Yeast based emulsion template have interconnected pore structure, which are significantly superior to other Pickering-HIPEs templates which are hard to form a similar pore structure. The open-cell superporous adsorbent containing a large number of COO− functional group has a fast capture rate and strong adsorption capability for radioactive Rb+, Cs+ and Sr2+ ions, and the saturated adsorption capacities are 179.69 mg/g (2.10 mmol/g), 229.52 mg/g (1.73 mmol/g) and 166.81 mg/g (1.90 mmol/g), and the equilibrium adsorption time are 30, 40 and 20 min, respectively. The porous adsorbent also has excellent regeneration ability and reusability, and maintains a high adsorption capacity after repeated use of five adsorption-desorption cycles. This study provides an environmentally-friendly and promising strategy for fabricating the interconnected superporous adsorbent for adsorption removal of radioactive metal ions.