浸渍活性炭性能和微观结构老化效应研究

为了研究老化引起的核级浸渍活性炭性能、结构上的变化,对现场应用老化及同批次自然老化后的浸渍活性炭,开展了吸附效率、关键物理性能、微观结构、热稳定性等变化特征的实验分析。研究发现,自然老化54个月的浸渍活性炭各性能指标变化不显著,但对于现场老化后吸附放射性甲基碘效率降至不足60%的浸渍活性炭,其CCl₄吸附率由初始的近60%显著下降至15%,pH值从9.7下降至7.2,碘吸附值下降至新浸渍活性炭的3/4,与除碘效率的下降趋势一致;SEM、N₂吸附测试表明,现场老化后的样品微观孔结构变化显著,孔道堵塞、磨损严重,比表面积减小,孔径增大;TG(失重实验)结果表明,现场老化后的浸渍活性炭在200~500 ℃失重约10%。这些理化性能及自身结构的变化是造成浸渍活性炭老化及除碘性能下降的重要原因。

Study on properties and structure changes of impregnated activated carbon induced by aging

In order to study the properties and structure changes of impregnated activated carbon caused by aging, the adsorption efficiency, key physical properties, microstructure and thermal stability of impregnated activated carbon aging through in-place application and natural aging in the same batch were analyzed. It was found that that the performance indicators change of impregnated activated carbon was not significant after natural aging for 54 months. While for the impregnated activated carbon aging in-place, its efficiency for adsorbing radioactive methyl iodine dropped to less than 60%, the CCl₄ adsorption rate dropped significantly from the initial nearly 60% to 15%, pH value decreased from 9.7 to 7.2, the iodine adsorption value fell to three-quarters that of new impregnated activated carbon, which is consistent with the declining trend of iodine removal efficiency. SEM and N₂ adsorption tests showed that the microscopic pore structure of the activated carbon samples after aging in-place changed significantly, the pores were blocked and worn seriously, the specific surface area decreased, and the pore width increased. Thermogravimetry (TG) test showed that the weight loss of impregnated activated carbon aging in-place was about 10% at 200-500 ℃. These changes in physical and chemical properties and structure are the main reasons for the aging and declining of iodine-removing properties of impregnated activated carbon.