Resource recovery from iodine-containing silver-loaded silica gel: recycling of silver and immobilization of iodine

Silver-loaded silica gel is widely used in spent fuel reprocessing plant due to its high adsorption efficiency of iodine and low influence of humidity and NO x . This study proposed a novel method for the disposal of iodine-loaded silver-silica gel. The elution of iodine using Na 2 S solution, the leaching of silver through HNO 3 solution. Subsequently, Zero-valent silver was synthesized via reduction of Ag + with NaBH 4 to recover silver. Additionally, the eluted iodide ions were transformed into iodosodalite and then combined with borosilicate glass powder for secondary immobilization. The results demonstrated that the elution efficiency of Na 2 S was 99.03%, the leaching efficiency of HNO 3 was 99.20%, and the recovery efficiency of Ag reached 86.93%. The iodine static saturated adsorption capacity of the silver-loaded silica gel prepared using recycled silver was 129.95 ± 3.46   mg/g, higher than original silver-loaded silica gel. In addition, the secondary immobilization body had a dense structure. The iodine leaching rate was 1.2×10 -4   g ⋅ m -2 ⋅ d -1 , which showed a good chemical stability. This work successfully realized the recycling of silver in iodine-containing silver-loaded silica gel and the safe disposal of iodine, which can provide new ideas for the disposal of iodine waste in spent fuel reprocessing plant.