Department of Nuclear Engineering, Kyoto University, Kyoto, Japan.
Institute for Integrated Radiation and Nuclear Science (KURNS), Kyoto University, Osaka, Japan.
J Hazard Mater. 2021 Jun 5;411:125071. doi: 10.1016/j.jhazmat.2021.125071. Epub 2021 Jan 7.
Solutions of humic acid (HA) were irradiated with 0, 1, 5, 10, 50, and 100 kGy of gamma irradiation using a Co source. The non-irradiated and irradiated HA molecules were fractionated by ultrafiltration into four categories: > 100, 50-100, 10-50, and < 10 kDa. Total organic carbon measurements and potentiometric titration analysis suggested that (1) some gamma-irradiated HA molecules were degraded into smaller molecules and (2) radiolytic degradation caused phenolic -OH became the predominant functional group in the small molecular-weight fractions of HA. The effect of absorbed dose of gamma rays on the distributions of Cs, Sr, and Eu ions in the molecular-weight fractions of the metal-HA systems was examined to discuss the complexation affinity. The metal ions were distributed in the smaller molecular-weight fractions at different doses, which corresponded to the degradation of HA molecules. For a predetermined absorbed dose, Cs ions did not change the molecular-weight distribution of the total organic carbon content of the degraded HA molecules. Conversely, the Sr and Eu ions redistributed organic carbon toward the larger molecular-weight fractions.
腐殖酸（HA）溶液经 Co 源 0、1、5、10、50 和 100 kGy 的γ射线辐照。未辐照和辐照的 HA 分子通过超滤分为四类：＞100、50-100、10-50 和＜10 kDa。总有机碳测量和电位滴定分析表明：（1）一些γ辐照的 HA 分子被降解成较小的分子；（2）辐射降解导致酚-OH 成为 HA 中小分子量分数中的主要官能团。研究了γ射线吸收剂量对金属-HA 体系中 Cs、Sr 和 Eu 离子在分子量分数中分布的影响，以讨论配合亲和力。金属离子在不同剂量下分布在较小的分子量分数中，这与 HA 分子的降解相对应。对于预定的吸收剂量，Cs 离子不会改变降解 HA 分子的总有机碳含量的分子量分布。相反，Sr 和 Eu 离子将有机碳重新分配到较大的分子量分数中。
