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REMOVAL OF OXYANION FORMING ELEMENTS FROM CONTAMINATED SOILS THROUGH COMBINED SORPTION ONTO ZERO-VALENT IRON (ZVI) AND MAGNETIC SEPARATION: ARSENIC AND CHROMIUM AS CASE STUDIES
Zhou, Z., Q. Alhadidi, K.Q. Deliz, H.Y. Greenslet, and J.-C. Bonzongo.
Soil and Sediment Contamination: An International Journal 29(2):180-191(2019)
Lab experiments were conducted to remediate soils contaminated with either As or Cr using zero-valent iron (ZVI) particles and magnetic separation techniques. In addition to total concentrations, the association of As and Cr with the different geochemical fractions in soils was determined before and after treatment by chemical sequential extraction. Results showed that >73% of initial total As and >92% of Cr were transferred from contaminated soils to ZVI particles. The particles were retrieved by magnetic separation with a ZVI recovery efficiency of 99%. Soil pH had a significant role in controlling As and Cr sorption onto ZVI particles. ZVI application rates (2.5% and 5%) affected the removal of Cr, but not of As. Using abandoned cattle dipping soils, with an initial arsenic concentration of 24.1 mg/kg, treatment with ZVI and magnetic separation decreased the initial concentration by 60.58%. In addition to reducing metal pollution in soil and potentially eliminating phytotoxicity, this combination of metal sorption onto ZVI and retrieval by magnetic separation could also help shift away from the current definition of remediation to a new paradigm, which would focus on the recovery of metal resources.
Soil and Sediment Contamination: An International Journal 29(2):180-191(2019)
Lab experiments were conducted to remediate soils contaminated with either As or Cr using zero-valent iron (ZVI) particles and magnetic separation techniques. In addition to total concentrations, the association of As and Cr with the different geochemical fractions in soils was determined before and after treatment by chemical sequential extraction. Results showed that >73% of initial total As and >92% of Cr were transferred from contaminated soils to ZVI particles. The particles were retrieved by magnetic separation with a ZVI recovery efficiency of 99%. Soil pH had a significant role in controlling As and Cr sorption onto ZVI particles. ZVI application rates (2.5% and 5%) affected the removal of Cr, but not of As. Using abandoned cattle dipping soils, with an initial arsenic concentration of 24.1 mg/kg, treatment with ZVI and magnetic separation decreased the initial concentration by 60.58%. In addition to reducing metal pollution in soil and potentially eliminating phytotoxicity, this combination of metal sorption onto ZVI and retrieval by magnetic separation could also help shift away from the current definition of remediation to a new paradigm, which would focus on the recovery of metal resources.
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