Dispersants and Related Oil Spill Technologies at the Nanoscale!

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vj@tulane.edu Dispersants and Related Oil Spill Technologies at the Nanoscale! Vijay T.

1 Dispersants and Related Oil Spill Technologies at the Nanoscale! Vijay T. John Department of Chemical and Biomolecular Engineering Tulane University Funding: Gulf of Mexico Research Initiative

2 Spill Conditions Limit Response Options Wave Height (feet) Natural Degradation and Dispersion Sea Conditions Mechanical Recovery Dispersant Application In-Situ Burning Courtesy of Al Allen Millimeters 1 10 Average Oil Thickness Courtesy ExxonMobil

3 The use of dispersants is an important oil spill response strategy. Dispersant Application Image courtesy Exxon Mobil Dispersant is a mixture of surfactants and solvents. Surfactant molecule Hydrophilic group Hydrophobic group Droplet formation and entrainment Oil droplets dispersed in water column

A Simple Dispersant Formulation with Food Grade Surfactants.

, Corexits), contain synthetic, non-food-grade surfactants.

emulsifier in mayonnaise, chocolate etc.

4 A Simple Dispersant Formulation with Food Grade Surfactants. Motivation: Current dispersants used to remediate oil spills, (e.g., Corexits), contain synthetic, non-food-grade surfactants. Overall Goal: To develop new dispersants for oil spills using nontoxic, food-grade amphiphiles. The dispersant should be comparable (or better) in its effectiveness compared to the Corexits. Our Main Result Zwitterionic, 2-tailed phospholipid: Used as emulsifier in mayonnaise, chocolate etc. + Tween 80 Nonionic, 1-tailed surfactant: Used as emulsifier in many foods, especially ice cream. = Effective dispersant of crude oil in sea water at 60:40 lecithin:t80 (comparable to Corexit).

Lecithin+Tween 80: Emulsifying Crude Oil Lecithin

homogenous and stable Initial After 30 min Corexit

5 minutes. Initial After 30 min Athas, J. C., Jun, K.

5 Lecithin+Tween 80: Emulsifying Crude Oil Lecithin (60%) + Tween 80 (40%) Observations: Emulsions remain homogenous and stable Initial After 30 min Corexit Observations: Emulsions became unstable within about 5 minutes. Initial After 30 min Athas, J. C., Jun, K., McCafferty, C., Owoseni, O., John, V. T., & Raghavan, S. R. (2014). An Effective Dispersant for Oil Spills Based on Food-Grade Amphiphiles. Langmuir, 30 (31),

Oil Spill Remediation: Gel Dispersants Dispersion by ocean waves and Biodegradation http://ehp.niehs.nih.

6 Oil Spill Remediation: Gel Dispersants Dispersion by ocean waves and Biodegradation oil oil Time Bacterial Colonization oil oil Oil-degrading Bacteria Biodegradation of suspended oil droplets Dispersants: surfactant blends dissolved in a hydrocarbon solvent applied to reduce oil-water interfacial tension. Liquid dispersants - suffer from spray drift, gets washed off by ocean currents when applied onto heavy or weathered oils and pose health risk to responders Gel based dispersants - potential advantages include (a) adherence to weathered oil (b) increased contact time with oil due to buoyancy (c) minimal solvent use (d) high surfactant concentrations Lessard, R.; Demarco, G. The significance of oil spill dispersants. Spill Sci Technol B 2000, 6 (1), Nedwed T. New dispersant delivered as a gel IOSC 2008; 121

Gel Buoyancy and Oil Dispersion Characteristics a c b d

PC/DOSS/Tween 80 gel (a) Oil is added to water surface (b)

gently with a stirrer (d) The oil is dispersed when the

droplets suspended in the water column by gel dispersant The

7 Gel Buoyancy and Oil Dispersion Characteristics a c b d Figure: Buoyancy and oil dispersion mechanism of PC/DOSS/Tween 80 gel (a) Oil is added to water surface (b) Dispersant gel is added to oil layer (c) the system is mixed gently with a stirrer (d) The oil is dispersed when the mixing speed is increased (e) Side-view of photograph in c (f) Side-view of photograph in d. Buoyant gel anchors to oil e f Oil is dispersed into droplets suspended in the water column by gel dispersant The DOSS/PC/Tween 80 gel anchors to the surface oil layer and disperses the oil into droplets suspended in the water column

8 Seeing phenomena at the micro and nanoscale using optical and electron microscopy Transmission Electron Microscope Scanning Electron Microscope

9 Cryo-Electron Microscopy to visually observe attachment of bacteria on oil droplet and exopolymer formed when the emulsion is formed by A.borkumensis bacterial culture 6 6 exposed surface of crude oil 200 μm 5 μm exopolymer 50 μm bacterial cell A.borkumensis populating a hexadecane droplet 50 μm exposed surface of crude oil 2 μm 500 nm A.borkumensis interconnected by exopolymer on the surface of Anadarko crude oil

10 Chemical Herding and In-Situ Burning BSEE- Bureau of Safety and Environmental Enforcement Using surfactants to thicken surface oil slicks chemical herding oil_spill_research/mitigation.html

11 Thank you!

APPLIED CHEMISTRY SURFACE TENSION, SURFACTANTS TYPES OF SURFACTANTS & THEIR USES IN TEXTILE PROCESSING

APPLIED CHEMISTRY SURFACE TENSION, SURFACTANTS TYPES OF SURFACTANTS & THEIR USES IN TEXTILE PROCESSING Lecture No. 13 & 14 2 Surface Tension This property of liquids arises from the intermolecular forces