It is important to understand nano-scale bubble (NB) transport in porous media for potential application of NBs in soil/groundwater remediation. It is expected that the bubble characteristics and solution chemistry of NB water highly influences the surface characteristics of NBs and porous media and the interaction between them, thus affecting the transport characteristics of NB. In this study, one-dimensional column transport experiments using glass beads with 0.1 mm size were conducted, where either air- or O2-NBs water were injected to the column with different flow rates. The turbidity, pH, EC, DO, and bubble size distribution in the effluent were measured. The bubble size distributions were measured using a resonant mass method. Effects of flow rate, bubble characteristics (gas species and bubble concentration), and solution chemistry (pH and ionic strength) on the NBs transport were investigated based on the column experiments. The results showed that relative turbidities (measured turbidity in the effluents / turbidity in the applied NBs water) during the NBs water injection were lower for NBs water at lower bubble concentration. In addition, O2-NBs showed higher relative turbidities in the effeluents as compared to air-NBs. Since zeta potential measurements showed that O2-NBs are more negatively charged than air-NBs, enhanced repulsive force between O2-NBs and glass beads might increase the mobility of O2-NBs. Attachment of NBs was enhanced for NBs water with higher ionic strength and lower pH conditions. The results can be also explained by the effects of solution chemistry on the surface charge of NBs.

Effects of bubble characteristics and solution chemistry on nano bubbles transport in saturated porous media

256th National Meeting (2018)

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