Elution of 17α 25-Norhopanes and Triaromatic Steroids from Weathered Soils by Mixed Triton X-100/Na_2SiO_3 Surfactant Solution

Sodium silicate（NazSiO3） 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 markers[C26-34 17a 25-norhopanes, C26-28triaromatic steroids（TAS）, and C27-29methyl triaromatic steroids（MTAS）] was monitored. The average elution percentages of C26-34 norhopanes, C26-28 TAS, and C27-29 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 elu- tion of TAS homologs containing fewer carbon atoms, whereas high concentrations improved the elution of larger 17a 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 surfac- rant 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.