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Dissolution and remobilization of NAPL in surfactant-enhanced aquifer remediation from microscopic scale simulations

Ramezanzadeh, M ; Sharif University of Technology | 2022

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  1. Type of Document: Article
  2. DOI: 10.1016/j.chemosphere.2021.133177
  3. Publisher: Elsevier Ltd , 2022
  4. Abstract:
  5. In this paper, the dissolution and mobilization of non-aqueous phase liquid (NAPL) blobs in the Surfactant-Enhanced Aquifer Remediation (SEAR) process were upscaled using dynamic pore network modeling (PNM) of three-dimensional and unstructured networks. We considered corner flow and micro-flow mechanisms including snap-off and piston-like movement for two-phase flow. Moreover, NAPL entrapment and remobilization were evaluated using force analysis to develop the capillary desaturation curve (CDC) and predict the onset of remobilization. The corner diffusion mechanism was also applied in the modeling of interphase mass transfer to represent NAPL dissolution as the dominant mass transfer process. In addition, the effect of pore-scale heterogeneity on mass transfer rate coefficient and recovered residual NAPL was considered in the simulations. Sodium dodecyl sulfate (SDS) and Triton X-100 were used as the surfactant for the SEAR process. The results indicate that although surfactants enhance NAPL recovery during two-phase flow, surfactant-enhanced remediation of residual NAPL through dissolution is highly dependent on surfactant type. When SDS ─as a surfactant with high critical micelle concentration (CMC) and low micelle partition coefficient (Km)─ was injected into a NAPL contaminated site, the mass transfer rate coefficient decreased (due to considerable changes in interface chemical potentials) which leads to a significant reduction in NAPL recovery after the end of two-phase flow. In contrast, Triton X-100 (with low CMC and high Km) improved NAPL recovery, by enhancing solubility at surfactant concentrations greater than CMC which overcompensates the interphase mass transfer reduction. © 2021 Elsevier Ltd
  6. Keywords:
  7. Dynamic pore network modeling ; NAPL dissolution ; NAPL remobilization ; Pore-scale heterogeneity ; Surfactant-enhanced aquifer remediation ; Aquifers ; Critical micelle concentration ; Micelles ; Recovery ; Remediation ; Sodium dodecyl sulfate ; Sulfur compounds ; Two phase flow ; Dynamic pore-network models ; Non-aqueous phase liquid dissolution ; Non-aqueous phase liquid remobilization ; Nonaqueous phase liquids ; Pore-scale heterogeneities ; Remobilization ; Surfactant enhanced aquifer remediation ; Surfactants-enhanced aquifer remediations ; Upscaling ; Dissolution ; Dodecyl sulfate sodium ; Surfactant ; Triton x 100 ; Ground water ; Mass transfer ; Modeling ; Nonaqueous phase liquid ; Aquifer ; Diffusion ; Flow ; Mass ; Partition coefficient ; Reduction (chemistry) ; Simulation ; Theoretical model ; Water flow ; Water pollutant ; Groundwater ; Models, Theoretical ; Solubility ; Surface-Active Agents ; Water Movements ; Water Pollutants, Chemical
  8. Source: Chemosphere ; Volume 289 , 2022 ; 00456535 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S0045653521036493