Size recognized separation of submicron particles by using acoustic cavitation bubbles

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05199
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 27010:Transport phenomena and unit operations-related
• Research Institution: Kagoshima University
• Principal Investigator: Nii Susumu 鹿児島大学, 理工学域工学系, 教授 (90262865)
• Co-Investigator(Kenkyū-buntansha): 五島 崇 鹿児島大学, 理工学域工学系, 助教 (90709560)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: submicron particle / Ultrasound / Separation / Cavitation

Outline of Final Research Achievements

It was confirmed that localization of submicron particles occurs through ultrasound irradiation. Increasing the concentration of dissolved gases in the sample suspension enhances separation and continuous bubbling of the gas enhanced the separation. Under the same conditions as particle separation, ultrasound irradiation of water saturated with argon gas resulted in approximately ten times more bubble generation compared to air-saturated water. The bubble diameter was approximately 100 nm for both gases, indicating that the presence of bubbles strongly influences the separation mechanism. High-speed video footage revealed explosive mist generation from the liquid column followed by liquid droplet fragmentation, suggesting the involvement of this phenomenon in particle separation.

Free Research Field

化学工学

Academic Significance and Societal Importance of the Research Achievements

本研究の成果は、サブミクロンサイズの粒子懸濁液への超音波照射という簡単な操作で粒子のサイズによる分離を可能にすることで、分離エネルギー低減と革新的な分離技術の創出の点で意義がある。従来法ではフィルターや膜などの消耗品を必要とする一方、超音波照射で生成する液柱の一部を取り出すという、非常に簡単な操作で分離ができる点が特徴である。本研究の学術的な意義として、複雑な分離メカニズムの解明に取り組み、分離場の形成には液中の溶存気体量、液中の気泡個数と液柱の挙動が深く関っていることまでを明らかにした。複数の相と速度が関わる分離場を理解することで、新しい分離場を創り出すことに貢献できる。