Core-shell Bi2S3 nanorods loaded ZIF-8 nanocomposites for efficient and reversible capture of radioactive iodine

Abstract

Large amounts of radioiodine are released during spent nuclear fuel reprocessing and nuclear reactor accidents. Effective capture and long-term storage of volatile radioactive iodine from aqueous as well as in the vapor phase are imperative due to its inherent properties of a long half-life, environmental mobility and high toxicity. However, the development of a fast adsorption rate, high adsorption capacity and thermally stable radioiodine adsorption material remains a challenge. Herein, a novel core-shell Bi 2 S 3 nanorods loaded ZIF-8 nanocrystals have been prepared via a facile, self-assembly procedure. The characteristics of as-synthesized Bi 2 S 3 @ZIF-8 (BZ) nanocomposites were investigated by various techniques such as scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), powder X-ray diffraction (P-XRD) and Fourier transform infrared spectroscope (FT-IR) spectra, revealing ZIF-8 nanocrystals with an average size of 150 nm securely loaded on the surface of the Bi 2 S 3 nanorods. Nitrogen sorption-desorption analysis showed that the as-synthesized BZ nanocomposites possess a high specific surface area (up to 1190.77 m 2 g −1 ). The absorption experiments demonstrated that as-synthesized BZ nanocomposites exhibited excellent iodine adsorption capacities for vapor-phase iodine (2627.0 mg g −1 at 350 K and under ambient pressure within 6 h) and liquid-phase iodine (up to 786.4 mg g −1 within 14 h). The removal mechanism study revealed that the remarkable performance might be ascribed to the combined action of the large specific surface area of ZIF-8 crystals and the strong chemical interaction of Bi 2 S 3 for I 2 to form thermodynamically stable BiI 3 . Given these excellent iodine adsorption capacity, ease of preparation as well as good thermal stability, the BZ nanocomposites could be a promising candidate for radioactive iodine elimination. • Core-shell Bi 2 S 3 Nanorods loaded ZIF-8 nanocomposites were synthesized via a facile, self-assembly procedure. • The maximum adsorption capacity of the BZ nanocomposites toward I 2 were 2627.0 mg g −1 and 786.4 mg g −1 for iodine vapor and solution, respectively. • Chemical adsorption accompanied by physical adsorption of I 2 played a key role in iodine capture.