Development of Supercritical Microfluidic Chemical Separation System

2021 Fiscal Year Final Research Report

• Project/Area Number: 18H01914
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 31010:Nuclear engineering-related
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: TSUKAHARA TAKEHIKO 東京工業大学, 科学技術創成研究院, 教授 (10401126)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: 超臨界二酸化炭素 / 核燃料サイクル / マイクロ流体 / 抽出分離

Outline of Final Research Achievements

Technologies and methodologies of supercritical microfluidics chemical system, which enables to separate target radionuclides using supercritical carbon dioxide (scCO2) media in 10nm-100 um-sized micro-nano channels, has been constructed. Micro-nano channels having different shapes and surface properties were fabricated, and selective extraction of metal ions through scCO2/water segment microflows. The scCO2/water microflows after extraction were continuously separated using an oil-water separator located at an exit port of the microchannel, and the concentrations of metal ions in the recovered water phase were measured by ICP mass spectrometry. The results showed that almost 100% extraction of metal ions such as uranyl ions was succeeded with a contact time of about 30 seconds. Compared with bulk-scale extraction, this supercritical microfluidics method makes it possible to complete the separation of metal ions at 3 digits faster or more without any secondary wastes.

Free Research Field

分析化学、放射化学、環境科学、マイクロ・ナノ化学

Academic Significance and Societal Importance of the Research Achievements

本研究は、高速・高効率な反応場であるマイクロ・ナノ空間と気体の拡散性と液体の溶解性を併せ持つscCO2を組み合わせることで、既存の核種分離法に付随する課題を解消し、精緻・迅速・無廃棄物な革新的な分離システムの基盤技術を構築することに成功している。従来のバルク的発想から、極限環境（微小空間と超臨界）でのみ発現するユニークな機能を十二分に利用して効率を劇的に向上させて処理量を稼ぐ、という発想を転換した技術であり、極めて独創的である。作業環境の安全性向上や作業員の負担軽減に繋がるため、廃棄物処理処分全体の安全性が大きく向上し、原子力科学に係る学術と工学に新しい展開をもたらすことができる。