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presentacion institucional.pptx

  1. ● Álvarez Jove Keyla Ester ● Hernández Miranda Keren María ● Miranda Arrieta Esteban José ● Petro Cantero Reny Sofía ● Suárez Zúñiga Luz Dey Professor: Monica Cecilia Cantero Benites In situ soil flushing to remediate confined soil contaminated with PFOS- an innovative solution for emerging environmental issue
  2. 1. INTRODUCTION Perfluorooctane sulfonate (PFOS) is a toxic anthropogenic chemical Soil and groundwater remediation strategies ● For soil remediation, activated carbon (AC) and montmorillonite ● For groundwater remediation, extraction with ion exchange resins, nonionic exchange resins, and AC adsorption. Other, such as thermal treatment, chemical oxidation methods and bioremediation. ETC In situ soil flushing is a mature technology to remediate soil contaminated with various organic and inorganic contaminants as it requires minimum excavatio, in addition, it involves minimum disturbance to the existing soil structure
  3. 2. METHODOLOGY 2.1. Proposed stages in the in situ flushing process 1- Solvent recovery 2- water treatment 3- mix treated water with organic solvent 4- spray the contaminated soil with the prepared solvent 5- transfer PFOS from soil to water 6- pump the contaminated water. Fig. 1. Suggested process of in situ flushing technology to remediate PFOS contaminated soil
  4. 2.2. Adsorbent pre-treatment 2.3. Soil collection, preparation and analysis ● K6362, Amberlite IRA 67, PFA694E, MP 62, Dowexoptopore V493, Dowexoptopore L493, Dowex MarathonA, Jacobi, Filtrasorb 400, Ovivo, Amberlite XAD 2, Amberlite IRA400 and Amberlite XAD 4) ● The filter materials were washed with deionized water ● The activated carbon types were first rinsed with deionized water and then washed in deionized water at 80 °C for 2 h. ● They were then dried in an oven at 105 °C for 48 h, crushed in a mortar and passed through a 0.25-0.5 mm sieve. ● A mini excavator was used ● They were stored in airtight polypropylene. ● They were air dried, homogenized and passed through sieves. ● The solid-liquid extraction method was used ● The soil samples were placed in polypropylene bottles. ● 100 ml of methanol were added ● Shaken for 24 hours and centrifuged ● The samples were analyzed by mass spectrometry.
  5. 2.4. Isothermal and kinetic experiment
  6. 2.5. Optimization of washing solvents and resins
  7. 2.6. Column experiment The soil physical characteristics of the site were simulated in the column by accurately maintaining soil density, moisture content, and permeability. Fig. 2. A schematic view of the column experiment test.
  8. 3. RESULTS AND DISCUSSION. 3.1. Potential site to implement the method 137 groundwater samples were collected from existing boreholes in the contaminated site and analysed for PFOS concentration using EPA method 537 Fig 3. Frequency distribution of PFOS concentrations in the analysed samples. The median PFOS level measured in this study was 64 times higher than the guideline set for drinking water.
  9. 3.2.Solvent optimisation Fig 4. Variation of equilibrium liquid phase PFOS concentration with various solvent concentrations of Ethanol, Methanol and Propanol. 50% ethanol is selected due to its better dissipation efficiency, lower environmental and human toxicity than methanol (metabolic acidosis, renal failure and blindness) and its very frequent application in other studies.
  10. It was observed that over 45%, 75% and 82% of PFOS was eliminated by the first, second and third bed volumes, respectively. Less than 2% of PFOS was retained in the soil after five bed volumes of solvent flushing. Fig 5. Efficiency of PFOS removal from column experiment on sandy soil. 3.3.Column experiment
  11. 3.4. Resin optimisation They showed comparatively higher adsorption capacity and faster adsorption kinetics. 3 types of granular activated carbon (GAC) The commercially available granular sorbent "Jacobi" showed better performance than the other two types of GAC. 3 types of non-ion exchange resins Amberlite IRA400 and Amberlite XAD 4, showed a PFOS adsorption capacity 2 to 3 times higher than that of Jacobi. 7 types of ion exchange resins
  12. Table 1 Freundlich constants and Pseudo-second-order kinetic parameters for PFOS with different adsorbents. Kinetic characteristics and isotherms of PFOS for various granular materials available on the market. PFOS adsorption capacity of adsorbents ↓ pH increases. Monovalent and divalent cations such as K + , Na + , Mg 2+ and Ca 2+↑ cap. adsorption of PFOS from the adsorbent
  13. The effectiveness of a method in soils with high permeability. The heterogeneity of the soil prevents the uniform distribution of the sln. of washing. Porosity is reduced-surfactants adhere to soil particles. PFAS and solvent can migrate to other areas- vadose zone-subterranean. Loss of groundwater quality due to solvents. The containment of soil contaminated with PFAS prevents migration of contaminants.
  14. Bibliography Senevirathna, S. T. M. L. D., Mahinroosta, R., Li, M., & KrishnaPillai, K. (2021). In situ soil flushing to remediate confined soil contaminated with PFOS-an innovative solution for emerging environmental issue. Chemosphere, 262, 127606.