[A-GE28] 地質媒体における物質移動，物質循環と環境評価

[AGE28-02] Nano-Bubble Retention in Saturated Porous Media under Different Solution Chemistry

*濱本 昌一郎¹、杉本 卓也¹、竹村 貴人²、西村 拓¹、Bradford Scott³ (1.東京大学大学院農学生命科学研究科、2.日本大学文理学部、3.アメリカ農務省塩類研究所)

キーワード：ナノバブル、輸送、多孔質体、溶液化学性

An understanding of nano-bubble (NB) migration in porous media is needed for potential environmental applications. This research investigates factors that control the transport, retention, and release of air NBs in repacked glass beads. One-dimensional column transport studies with air NBs were conducted under different solution IS, ionic composition, and pH conditions. Collected data were simulated using a mathematical model that considered advective and dispersive transport, first-order kinetic retention, and transient release. Results were interpreted with the aid of interaction energy calculations that considered electric double layer, van der Waals, and Lewis acid-base interactions on surfaces with different amounts of nanoscale roughness. NB concentrations in the effluent were reduced with an increase in ionic strength (IS) or a decrease in pH due to a reduction in the repulsive force between the glass surface and NBs, especially when the solution contained Ca²⁺ as compared to Na⁺ and for larger NBs. NB retention on the surface was explained by ubiquitous nanoscale roughness on the glass beads that significantly lowered the energy barrier, and localized attractive charge heterogeneity and/or hydrophobic interactions.