Partial reflections

Johnston, Andrew James; Marks, Benjamin

doi:10.1145/1254960.1255001

Cited by 1 publication

(1 citation statement)

References 2 publications

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“…Oily wastewater is generated from a wide range of industrial activities. − For example, hydraulic fracturing of geologic formations in the pursuit of oil and gas generates large volumes of produced water which can contain large amounts of emulsified oil. − In the United States, there are approximately 60 million barrels of produced water generated daily . The disposal of this water often requires transportation to remote deep-well injection sites, dramatically increasing the cost of produced water treatment. , Another example is the treatment of oil-contaminated bilge water . Traditional gravity-based separation methods are effective at removing large and unstable oil droplets (>10 μm) .…”

Section: Introductionmentioning

confidence: 99%

Field-Induced Redistribution of Surfactants at the Oil/Water Interface Reduces Membrane Fouling on Electrically Conducting Carbon Nanotube UF Membranes

Zhu

Dudchenko

Khor

et al. 2018

Environ. Sci. Technol.

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Membrane-based treatment of oily wastewater remains a significant challenge, particularly under high salinity conditions. The main difficulty associated with this separation process is membrane fouling, mostly caused by wetting and coalescence of emulsified oil droplets on the membrane surface. In this study, electrically conducting carbon nanotube-based ultrafiltration membranes were used to treat an emulsified oil suspension at ionic strengths as high as 100 mM. By tuning the electrical potential applied to the membrane surface, we demonstrate how fouling can be dramatically reduced, even under high salinity conditions. Permeate water quality is shown to improve upon application of a negative potential. Using optical microscopy, we observed dramatic changes in the shape of oil droplets at the membrane/water interface in response to the applied electric potential; this change is associated with a redistribution of charged surfactant molecules at the oil/water interface in response to the external electric field. Specifically, using the membrane as a cathode repels surfactant molecules away from the oil/membrane interface, while anodic conditions lead to increased surfactant concentrations. We speculate that this change in surfactant molecule distribution is responsible for changes in the surface tension of oil droplets at the membrane/water interface, which results in a decrease in oil coalescence and subsequent fouling. The membranes used in this study offer an attractive treatment option when separating emulsified oil from water under high salinity conditions.

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