An innovative method for the solidification/stabilization of PAHs-contaminated soil using sulfonated oil

Area of Science:

• Environmental Engineering
• Geotechnical Engineering
• Soil Remediation

Background:

• Stabilization/solidification (S/S) is used for organic contaminants but has long-term effectiveness concerns and increases soil volume.
• Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants requiring effective soil remediation strategies.

Purpose of the Study:

• To develop and evaluate a novel S/S method for PAH-contaminated soil using sulfonated oil (SO).
• To assess the impact of SO on soil strength, PAH leaching, and durability under freeze-thaw cycles.

Main Methods:

• Soil samples were treated with Portland cement, activated carbon (PC-AC), and varying concentrations of SO.
• Unconfined compressive strength (UCS) tests, leaching tests, freeze-thaw durability tests, and Scanning Electron Microscopy (SEM) were performed.

Main Results:

• SO addition increased UCS values by up to 2.3 times compared to PC-AC treatment alone.
• PAH leaching concentrations were reduced to 14%-25% of control soil, with minimal leaching of high molecular weight PAHs.
• Treated soils showed improved resistance to disintegration and enhanced compactness after freeze-thaw cycles.

Conclusions:

• The novel PC-AC-SO method significantly improves the mechanical properties and contaminant immobilization of PAH-contaminated soils.
• SO enhances the long-term effectiveness and durability of S/S treatment for contaminated soils, addressing limitations of conventional methods.