Efficient capture of iodine by a polysulfide-inserted inorganic NiTi-layered double hydroxides

Abstract

Effective capture of radioactive iodine is highly desirable but still remains a significant challenge. We reported here a polysulfide (Sx2−) intercalated inorganic cationic Ni-Ti layered double hydroxide, NiTi-Sx-LDH, which was prepared by coprecipitation method and ion exchange method for efficient capture of iodine. Due to the strong chemical attraction between the soft Lewis base Sx2− and the soft Lewis acid I2, and the reducing property of Sx2−, NiTi-Sx-LDH exhibits highly efficient iodine capture. During the adsorption process, I2 is reduced to I3− by the intercalated Sx2−. In combination with chemical adsorption and physical adsorption, the adsorption capacity of NiTi-Sx-LDH to iodine vapor reaches 52% (wt%). In addition, the adsorption properties of NiTi-Sx-LDH on elemental iodine in organic solvent cyclohexane were also studied, and the maximum adsorption capacity of NiTi-Sx-LDH for iodine reaches up to 527.4 mg/g. Compared with various sorbents for iodine, it is cost-effective, capable of achieving scale-up preparation, and the good performance for the iodine adsorption suggests that NiTi-Sx-LDH may be considered as a promising sorbent for efficient removal of radioactive iodine from reprocessing plant off-gas streams.