Elution of 17α 25-Norhopanes and Triaromatic Steroids from Weathered Soils by Mixed Triton X-100/Na2SiO3 Surfactant Solution

Sodium silicate(Na₂SiO₃) was used to improve the elution of super heavy oil from weathered soil on an ultrasound-enhanced elution system by the solution containing 0―6000 mg/L surfactant Triton X-100. The removal extent of three markersC_26―34 17α 25-norhopanes, C_26―28 triaromatic steroids(TAS), and C_27―29 methyl triaromatic steroids(MTAS)] was monitored. The average elution percentages of C_26―34 norhopanes, C_26―28 TAS, and C_27―29 MTAS by Triton X-100/Na₂SiO₃ solutions were increased by 11%―13%, 9%―11% and 8%―13% with increasing Triton X-100 concentrations from 150 mg/L to 6000 mg/L. All the concentrations of Triton X-100 improved the elution of TAS homologs containing fewer carbon atoms, whereas high concentrations improved the elution of larger 17α 25-norhopane and MTAS species. Addition of Na₂SiO₃ produced a noticeable increase in elution, particularly for lower-weight species. Scanning electron microscope(SEM) images and energy spectroscopy data reveal that surfactant solution of 6000 mg/L Triton X-100 and 4000 mg/L Na₂SiO₃ produced the greatest improvement in the elution of super heavy oil aggregates encapsulating the soil surface and the emulsification of particle dispersions. That is to say mixed solutions of Triton X-100 and Na₂SiO₃ in combination with ultrasound are a potential means of removing super heavy oil from weathered soils.