Application of Electrokinetics for Enhanced Oil Recovery - Electrokinetics for Petroleum and Environmental Engineers - page 139

Day 36

Baseline

100%

100%

400
6:41

800
13:41

1200
20:01

1600
26:41

2000
33:21

600
10:01

1200
20:01

1800
30:01

2400
40:01

100%

Day 70

600
10:01

1200
20:01

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40:01

Figure 3.24 EC PAH destruction documented by GCMS changes, with time, During
Treatment (after, Döring et al, 2000). Vertical axes are abundance in ppm; horizontal axes
time, in minutes.

(ECGO) provides insight for yet another potential explanation of the Santa
Maria Basin DCEOR results.
Figure 3.24 shows a series of Gas Chromatography Mass Spectrograph
(GCMS) spectras taken at various times during in-situ ECGO remediation
a large-scale poly-aromatic hydrocarbon (PAH) contaminated soil site.
The GCMS spectra vertical axes are relative to hydrocarbon (HC) species
concentration. The horizontal axes are residence times, which are related
to the HC species complexity.
The simpler PAH species are vaporized with shorter residence times
(left end of the axis), while the more complex species require longer resi-
dence times (right end of the axis). Over the course of the site remediation,
the GCMS spectra peaks shift from complex to simpler hydrocarbons (i.e.,
to the left, on the GCMS spectra), suggesting a possible in-situ breakdown
of the complex PAH molecules to simpler hydrocarbon daughter products.
The measurement samples were not collected near the electrodes, but from
the body of the contaminated soil site. As a result, the chemical changes in
the PAH were not just occurring at the cathodes, or as a result of electrode
reactions.