Study On The Construction Of Collagen Composite Nano-aerogel And The Adsorption Of Iodine

With the rapid development of the nuclear industry,radionuclides will inevitably leak and remain in the environment during nuclear applications and spent fuel reprocessing.Radioactive iodine has attracted much attention due to its ultra-long half-life,high activity,and easy accumulation.In view of the problems of high cost,complex preparation process and low adsorption capacity of existing iodine removal materials,this paper uses low-cost tannery waste collagen fibers,collagen（gelatin）and hydroxyapatite as raw materials.Three adsorption materials,Ag⁰@BT-n CF,Ge Aerogel,and HAP-Ge Aerogel,were prepared by a simple and convenient method,and their adsorption and removal performance for constant iodine vapor（I₂）in a simulated gaseous environment was studied,which was a collagen-based material for the adsorption and removal of radioactive iodine in the actual environment provides a new idea.（1）A multi-layer active interface material（Ag⁰@BT-n CF）with highly dispersed collagen fibers loaded with zero-valent silver nanoparticles was prepared by chemical cross-linking combined with redox method.The capture results of constant iodine vapor（I₂）in a simulated gaseous environment show that the adsorption capacity of Ag⁰@BT-n CF for iodine reaches1,704.34 mg/g within 72 h at 75℃,which was 64.5%and 34.9%higher than that of n CF and BT-n CF,respectively.It is found that Ag⁰ mainly reacts with iodine vapor to form Ag I,and-OH,-CONH₂ and-NH on the surface of BT-n CF also participate in the chemical adsorption of iodine.In addition,within a certain temperature range,Ag⁰@BT-n CF exhibits excellent stability after capturing iodine,which can effectively prevent the volatilization and escape of iodine.（2）In order to improve the adsorption performance of the material for iodine,we prepared a porous aerogel adsorption material（Ge Aerogel）by freeze-drying with gelatin as the raw material.The capture results of constant iodine vapor（I₂）in a simulated gaseous environment show that Ge Aerogel has the best adsorption performance for iodine at 75℃when the mass fraction of gelatin is 1.5%.At 72 h,the adsorption amount reached 1,449.53 mg/g.Compared with n CF,Ge Aerogel showed a significant increase in the adsorption amount of iodine.The analysis results show that Ge Aerogel with a mass fraction of 1.5%has a good pore structure,and its specific surface area,pore diameter and pore volume are 15.0325 m²/g,6.37498 nm and 0.024456 cm³/g,respectively.These properties endow the material with better adsorption.performance.In addition,the results also demonstrate that the effective adsorption of iodine vapor（I₂）by Ge Aerogel is attributed to the chemical bonding with the exposed valence structure inside the aerogel as well as the physical adsorption.（3）Based on the previous research basis,we used the cross-linking effect of glutaraldehyde to introduce hydroxyapatite into the collagen substrate,and prepared the porous material HAP-Ge Aerogel by a simple freeze-drying technology.The capture results of constant iodine vapor（I₂）in a simulated gaseous environment show that when the dosage ratio of hydroxyapatite to gelatin was 0.1:1,the obtained material has a good pore structure,and its specific surface area,pore diameter,pore volume 24.9266 m²/g,9.61208 nm and0.059899 cm³/g,respectively.The material not only showed excellent adsorption performance for iodine vapor,its adsorption capacity reached 2,423.97 mg/g at 75℃,but also the adsorption efficiency was significantly improved（24 h）.Through characterization analysis,it was found that the adsorption of HAP-Ge Aerogel with iodine vapor（I₂）was attributed to the active groups on the surface of the material,that is,chemical complexation and physical adsorption between-OH,-CONH₂,and-NH and iodine molecules.