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The application of chemical dispersants to oil-contaminated areas has long
been used as a primary response to mitigate the impacts of the spill. The estimate
of chemical dispersants used has ranged from 5500 gallons of dispersant used
during the 1989 Exxon Valdez spill to 2.1 million gallons of dispersant used during the DWH spill (Kujawinski et al. 2011). Chemical dispersants aid in breaking
down larger oil slicks into smaller sized oil droplets by reducing the surface tension between oil and water particles, thereby enhancing the natural dispersion.
With surfactants as the key component of their chemistry, dispersants emulsify oil
and help break down larger clumps of high molecular weight viscous oil, reducing
the risk of surface slicks to birds and mammals and preventing the stranding of oil
on sensitive shorelines. While the physical effect of breaking oil into smaller
droplets is beneficial, there are conflicting views concerning the potential risks for
human and environmental health posed by the use of dispersants (Bostrom et al.
2015; Kleindienst et al. 2015; Prince et al. 2016a). Considering the high volume
of dispersant previously used as a critical response to oceanic oil spills and the
novel deep-sea application during DWH, it becomes imperative to understand the
impact and effectiveness of dispersant addition on the partitioning of the organics
along the water column gradients.
The traditional methods for determining oil-water partition ratios use the shake
flask technique (Xie et al. 1984; Shiu et al. 1990; Taylor et al. 1997), which is performed using “dead” oil (i.e., oil at ambient pressure and temperature [PT] conditions, devoid of dissolved solution gas). This approach cannot account for the
changes in composition of the liquid hydrocarbon phase under the large variations
in pressure and the low temperatures found in deep submarine oil spill conditions.
In addition, such procedures commonly lead to the loss of volatile BTEX components due to evaporation. To experimentally simulate the partition behavior for
submarine oil spill conditions, a customized instrument to measure the partition
ratios of organic solutes between methane-charged “live” crude oil and water under
high- pressure and low-temperature conditions typical of a deep submarine oil spill
was built (Figs. 8.1 and 8.2). The data obtained from this study help to quantify the
partitioning behavior of BTEX compounds under varying environmental conditions and could be used to predict their partitioning trends in any future submarine
oil spill, as well as for pollutant plume migration and toxicity modeling.
8.2 Partition Device
The in-house-built instrument was adapted from the concepts of Bennett et al.
(2003), where partition ratios for alkylphenols in an oil-water system were investigated under reservoir conditions. This approach was modified to design and
build the Partition Device, capable of simulating deep-sea conditions of high
pressure and low temperature by adding a temperature-controlled separator region
and pressurized sampling loops. The partition device comprises five main
8 Partitioning of Organics Between Oil and Water Phases with and Without…
The application of chemical dispersants to oil-contaminated areas has long
been used as a primary response to mitigate the impacts of the spill. The estimate
of chemical dispersants used has ranged from 5500 gallons of dispersant used
during the 1989 Exxon Valdez spill to 2.1 million gallons of dispersant used during the DWH spill (Kujawinski et al. 2011). Chemical dispersants aid in breaking
down larger oil slicks into smaller sized oil droplets by reducing the surface tension between oil and water particles, thereby enhancing the natural dispersion.
With surfactants as the key component of their chemistry, dispersants emulsify oil
and help break down larger clumps of high molecular weight viscous oil, reducing
the risk of surface slicks to birds and mammals and preventing the stranding of oil
on sensitive shorelines. While the physical effect of breaking oil into smaller
droplets is beneficial, there are conflicting views concerning the potential risks for
human and environmental health posed by the use of dispersants (Bostrom et al.
2015; Kleindienst et al. 2015; Prince et al. 2016a). Considering the high volume
of dispersant previously used as a critical response to oceanic oil spills and the
novel deep-sea application during DWH, it becomes imperative to understand the
impact and effectiveness of dispersant addition on the partitioning of the organics
along the water column gradients.
The traditional methods for determining oil-water partition ratios use the shake
flask technique (Xie et al. 1984; Shiu et al. 1990; Taylor et al. 1997), which is performed using “dead” oil (i.e., oil at ambient pressure and temperature [PT] conditions, devoid of dissolved solution gas). This approach cannot account for the
changes in composition of the liquid hydrocarbon phase under the large variations
in pressure and the low temperatures found in deep submarine oil spill conditions.
In addition, such procedures commonly lead to the loss of volatile BTEX components due to evaporation. To experimentally simulate the partition behavior for
submarine oil spill conditions, a customized instrument to measure the partition
ratios of organic solutes between methane-charged “live” crude oil and water under
high- pressure and low-temperature conditions typical of a deep submarine oil spill
was built (Figs. 8.1 and 8.2). The data obtained from this study help to quantify the
partitioning behavior of BTEX compounds under varying environmental conditions and could be used to predict their partitioning trends in any future submarine
oil spill, as well as for pollutant plume migration and toxicity modeling.
8.2 Partition Device
The in-house-built instrument was adapted from the concepts of Bennett et al.
(2003), where partition ratios for alkylphenols in an oil-water system were investigated under reservoir conditions. This approach was modified to design and
build the Partition Device, capable of simulating deep-sea conditions of high
pressure and low temperature by adding a temperature-controlled separator region
and pressurized sampling loops. The partition device comprises five main
8 Partitioning of Organics Between Oil and Water Phases with and Without…