2024-01-02 パシフィック・ノースウェスト国立研究所(PNNL)
◆研究者は、アルミニウムベースの鉱物であるギブサイトの放射線による溶解挙動を調査しました。照射されたサンプルは乾燥またはNaOHの溶液中で比較され、照射により溶解速度と粒子の粗さが向上することが判明しました。
◆特にNaOH溶液中で照射されたサンプルは他のサンプルと比較して大きな増加を示しました。これは放射線が溶液とギブサイトの両方に影響を与え、水酸化ナトリウムが高反応性の過酸化物に変わり、ギッブサイト表面でさらなる反応を引き起こす効果が組み合わさった結果と考えられます。この研究は、放射線が材料の重要なプロセスに及ぼす影響を基本的に理解する手がかりとなります。
＜関連情報＞
- https://www.pnnl.gov/publications/directly-measuring-x-ray-enhanced-dissolution-gibbsite
- https://pubs.acs.org/doi/full/10.1021/acs.jpcc.3c02817
X線照射により増強された鉱物溶解の直接測定 Direct Measurement of Mineral Dissolution Enhanced by X-ray Irradiation
Shawn L. Riechers, Xin Zhang, Jay A. LaVerne, and Kevin M. Rosso
The Journal of Physical Chemistry C Published:September 6, 2023
DOI:https://doi.org/10.1021/acs.jpcc.3c02817
Abstract
Developing a predictive understanding of mineral-phase stability in extreme chemical conditions such as those found in nuclear waste is challenging given the unknown influence of ionizing radiation. The long-term impacts of cumulative radiation damage in the solid state and exposure to radiolysis products in solution can impact mineral precipitation, dissolution, and aggregation behavior. Here, we sought to disentangle some of these effects by examining the dissolution of gibbsite platelets in NaOH solutions using atomic force microscopy with an integrated X-ray source that was used to compare dissolution rates when particles were initially irradiated in a dry state versus irradiated in solution, both of which were compared to unirradiated controls. By tracking particle morphology changes and quantifying material lost over time, dissolution rates and particle roughness were found to be enhanced most when irradiation was carried out during dissolution in NaOH, and to a lesser but significant extent when irradiated dry prior to dissolution. The maximum observed dissolution enhancement in the former case suggests the importance of both a direct effect of absorbed dose on gibbsite stability and an indirect effect arising from surface interaction with solution radiolysis products.
