The Use of Natural Dispersants and their Implications for Deepwater Horizon Oil

Spill Remediation

Dr. Dawn Fox, Dr. Maria T. Celis, Dr. Ryan Toomey, Dr. Daniela Stebbins, and

Dr. Norma A. Alcantar norma@usf.edu

Nanosurface-Chemistry and Green Materials Chemistry Laboratory

C-MEDS: Consortium for the Molecular Engineering of Dispersants Systems

Lead Institution: Tulane University

Gulf Research Initiative (GoMRI)

Cactus Mucilage The Opuntia ficus-indica cactus (a.k.a. Nopal or prickly pear) produces a gum-like substance: MUCILAGE

Nopal mucilage is an important constituent of the cactus: a thick, gum-like substance precipitates ions, heavy metals,

bacteria, and particles has special surface active

characteristics provides the cactus’ ability to store

large amounts of water

Nopal mucilage is an important constituent of the cactus: a thick, gum-like substance precipitates ions, heavy metals,

bacteria, and particles has special surface active

characteristics provides the cactus’ ability to store

large amounts of water

T = 0 min T = 10 min

20 nm

Nopal mucilage is an important constituent of the cactus: a thick, gum-like substance precipitates ions, heavy metals,

bacteria, and particles has special surface active

characteristics provides the cactus’ ability to store

large amounts of water

Nopal mucilage is an important constituent of the cactus: a thick, gum-like substance precipitates ions, heavy metals,

bacteria, and particles has special surface active

characteristics provides the cactus’ ability to store

large amounts of water

Mucilage Extracts

COMBINED GE + NE

Macerated Pads

GE Gelling extract

fraction of raw mucilage

NE Non-gelling extract

fraction of raw mucilage

Effect of mucilage on surface oil

The mucilage is able to disperse oil

Surface tension vs. concentration of cactus mucilage, NE ( %W/V)

Our initial approach is to study the surface active properties of mucilage/oil dispersions

Research Approach Static analysis Dispersion particle size and distribution Stability Effect of salt in the dispersion

Droplet size of Oil/water/NE mucilage [30:70:%W/V]

10001500200025003000350040004500500055006000

0 0.5 1 1.5

Num

ber a

vera

ge d

iam

eter

(nm

)

Cactus mucilage concentration (w/v. % )

GE

NE

Combined

Dynamic analysis Shear rate effects Structural changes of the dispersant under various

shear rates Effect of salt and mucilage (dispersant) concentration

2700

2900

3100

3300

3500

3700

3900

0 3 6 9 12 15

Num

ber

aver

age

diam

eter

(nm

)

Salt concentration (w/v .%)

Variation of droplet size Mineral oil / water / mucilage

Function of salt concentration [0.5 mucilage w/v.%]

NE

GE

Combined

Surface Forces Apparatus

Scalability, cost, and life cycle assessment

Acknowledgements

Gulf Research Initiative C-MEDS Tulane University Vijay John, Keith Johnston, Arijit Bose, Kalliat Valsaraj, All members and staff of C-MEDS

National Science Foundation CBET: 1057897 under Dr. Robert Wellek’s division

Phase-Selective Organogels (PSOs): Eco-Friendly Oil Spill Clean-Up Materials from Sugars

Objective: The goal of this proposal is to underpin the design principles to develop molecular gelators from biomass, that are biodegradable, efficiently gels crude oil and crude oil fractions, facilitate removal of oil gel from water surface and subsequent recovery of oil. Specifically:

1) to systematically study the influence of (a) the stereochemistry of sugars, and (b) the hydrophobicity of the fatty acid part of the ‘gelator’ (amphiphile).

1) to study the microstructure, viscoelasticity and thermoreversibility behavior of the gel.

Gulf of Mexico Research Initiative

George John, Depar tment of Chemistr y The City College of the City University of New York, E-mail: john@sci.ccny.cuny.edu

FRG - 3

Design and Synthesis

The concept is: i) to design amphiphilic

molecules that preferentially partition into the organic phase as well as exhibit a balance between dissolution into and crystallize out of the organic solvent.

ii) to develop a method for the gelation at ambient temperature thereby rendering it more energy efficient and practical towards oil spill clean-up technologies.

Scheme 1: Enzymatic Synthesis of Amphiphiles

FRG - 3

Gulf of Mexico Research Initiative

Preliminary Data and Plan

• To better elucidate the gelation mechanism of the PSO in crude oil, we plan to characterize the crude oil gels by various physico-chemical techniques like microscopy (optical and SEM), scattering (X-ray diffraction) and rheology.

FRG - 3

Gulf of Mexico Research Initiative

Scheme 1: Phase-Selective Gelation of Oils

Implication of Work

The overall implication of work with crude oil is that: • The PSOs have not only exhibited the potential to be

used for cleaning up of refined oils such as diesel, but have exhibited the potential for crude oil spill remediation.

• The starting materials being biomass and abundant in

nature render the PSO derivatives to be biodegradable, environmentally friendly and relatively inexpensive to produce for large scale applications.

Gulf of Mexico Research Initiative

FRG - 3

frhung@lsu.edu http://www.che.lsu.edu/faculty/hung

Adsorption of hydrocarbons and dispersants on atmospheric air/salt water interfaces

Francisco R. Hung Cain Department of Chemical Engineering, Louisiana State University,

Baton Rouge, LA, USA

2

Rationale • Large fraction of oil from 2010 DWH

accident accumulated on sea surface

• Volatile organic compounds (VOCs) evaporate; but intermediate (IVOC) and semi-volatiles (SVOC) remain on sea surface

• Bubble-bursting, white caps will carry IVOCs, SVOCs, dispersants into atmosphere; preliminary results (Valsaraj) suggests these mechanisms are important

• Neglected in previous studies Figure courtesy of K. T. Valsaraj

• Classical molecular dynamics (MD) simulations of adsorption of organics at salt water/air interfaces, when surfactants/dispersants are absent/present

• In collaboration with K. T. Valsaraj (experiments) • Fundamental understanding of interfacial properties → determine which/how much

organics were transported into atmosphere, contribute to aerosolization

3

Proposed work • MD simulations of adsorption of organics at salt water/air

interfaces, when surfactants/dispersants are absent/present • Alkanes of different chain lengths (C15-C39) → oil mousse

samples • Water + NaCl • Standard surfactants; also model compounds from Corexit

9500/9527

• Determine: • Potentials of mean force • Interfacial properties (density profiles, order parameters,

surface tension, radial distribution functions)

Slab with aqueous salt solution

Vacuum region (air)

y

z

x

Sodium dodecyl sulfate (SDS)

O

OHOHHO

O

O

Sorbitan monooleate

0

0.2

0.4

0.6

0.8

1

-20-10

0102030405060

10.5 11.5 12.5 13.5D

ensi

ty (a

rbitr

ary

units

)

PMF

(kJ/

mol

)

Z-axis (nm)

PMF

W

4

Preliminary results Potentials of mean force

C15

• Next: interfacial properties; larger alkanes; dispersants • Combine with experiments from Valsaraj’s group → Fundamental understanding of

interfacial properties → determine which/how much organics were transported into atmosphere, contribute to aerosolization

0

0.2

0.4

0.6

0.8

1

-40-20

020406080

100

10.5 12.5 14.5

Den

sity

(arb

itrar

y un

its)

PMF

(kJ/

mol

)

Z-axis (nm)

PMF

W

C30

Environmental Implications of Alternative Dispersants

Robert Hurt and Agnes Kane

Institute for Molecular and Nanoscale Innovation;

School of Engineering, Dept. of Pathology and Laboratory Medicine

Brown University, Providence, Rhode Island, USA

Presented at the GRI Review Meeting, San Diego, March 2012

Core competencies: environmental / health implications of emerging technologies, toxicology, nanomaterial fate, transport, and transformation in enviro/bio-systems

Visiting Prof. Rene Rangel-Mendez

Ph.D. student Megan Creighton

Engineering the hydrophilic / lipophilic balance (HLB)

Performance and Implications of Particle-Based Dispersants

The extent of functionalization influences:

The free energy driving force for assembly of Pickering emulsions

The toxicity and bioaccumulative tendency of nanoparticles surface treatment to impart hydrophilicity is observed to decrease nanotoxicity by an unknown mechanism. Membrane disruption? Protein interactions? hydrophobicity favors partitioning to fatty tissues and bioaccumulation

The adsorption of toxic aromatic petroleum fractions and bioavailability reduction aromatic adsorption is driven by hydrophobic forces; reduced by hydrophilic treatment?

Prof. Arijit Bose, URI

Stages of Larval Development Williams, Biol. Bull., 187, 164, 1994 Ingestion of carbon black nanoparticles by a metanauplius 48 hours after hatching – exposed to

10 ppm (1mg/L) for 4 hours with no toxicity.

Preliminary Data on Aromatic Adsorption and Ecotoxicity

Adsorption behavior

Model Organism: Artemia

LC50 = 10 μg/ml 30% decrease in GSH after 24 hours Ruebhart et al., J. Toxicol. Environ. Health, 72, 1567, 2009 Criddle et al., J. Biol. Chem., 281, 40485, 2006

1. Toxicity Endpoints • Reduced motility and

death • Depletion of GSH • Lipid peroxidation

2. Stress Responses • Heat shock proteins (hsc 70,hsp 21, p26) • Iron binding protein (artemin)

Ecotoxicity in Artemia: Particles, Aromatics, and Their Mixtures

FIRST FOCUS: BENZENE / PARTICLES

Cytochrome P450 metabolism

FUTURE: BIOACCUMULATION

Thermodynamic and Interfacial Behaviors in Hydrate Forming Emulsions

Jae W. Lee, Chemical Engineering, The City College of New York

Goals: 1) Determine phase equilibria of hydrate forming emulsions. 2) Examine interfacial behaviors of hydrate particles in various

environments.

µ−DSC

Figure 1. CP hydrate equilibrium temperature.

Hydrophobicized Silica Pickering Emulsion

60 to 40 vol. % of Cyclopentane to H2O 7nm Silica Particle

1.0, 2.5, 5.0, and 7.5 wt %

CP Hydrate Equilibria Determined by DSC wt% (in

CP) Hydrate Dissociation

(oC) - Average 1 6.58

2.5 6.15 5 6.00

7.5 5.53

0.0 2.5 5.0 7.5 10.00

5

10

15

Emul

sion

Aver

age

Size

(micr

on)

Future Plans 1) Determine phase equilibria of CP hydrates in silica

emulsions with electrolytes and surface-active agents. 2) Oil-water interfacial tensions In Tensiometer (low T, electrolyte) 3) Adhesion force measurements

Oil-Soluble Components Water Soluble Components

Surface-active agents

AOT, Span 65/80, C16E1 SDS, DTAB, Triton X100, PVP, PVCap

Non-soluble particles

Fe2O3 (20 – 100 nm), Janus (0.8 – 8 µm): Hydrophobic silica-Fe deposition

Hydrate former Cyclopentane, methane Tetrahydrofuran (THF), Acetone

Non-hydrate former

Decane, Light mineral oil NaCl (0 – 600 mM)

Operating T & P 273.16 K – 280 K & 1 bar – 100 bar

Water

Oil

Water

Oil

Contact&

Detach)

c)

Microstructures of poly-(ethylene) oxide chain solute in water and

n-hexane solutions

Hot Oil-Cold Seawater Interaction at Depth

Amitava Roy J. Bennett Johnston, Sr., Center for Advanced Microstructures and

Devices (CAMD), Louisiana State University, Baton Rouge, Louisiana

Objectives: Study droplet/ bubble formation, their size distribution, composition and thermodynamic properties at the microscopic scale in the presence of dispersants at pressures comparable to DWH spill.

Concept and Physical Principles

• Based on molecular weight and solubility in different

solvents, crude oil is composed of several fractions • During production and processing phase separation can

occur easily • Interaction of hot oil mixed with seawater at depth

should lead to phase separation and precipitation

Preliminary Data/Plans All components, including gas, will be considered in this study • Small and Wide Angle Scattering (X-ray, light(?),

and neutron (?)) • X-Ray Diffraction • Differential Scanning Calorimetry 1. Experiments will be conducted in experimental cells at

pressures and temperatures comparable to DWH spill. 2. CAMD’s SAXS beamline may be an ideal beamline for

this study where the flux is not too high to volatilize low boiling point components.

3. All these techniques can be combined at a synchrotron beamline (for example, the Photon Factory, at Tsukuba, Japan; DND-CAT at the Advanced Photon Source, Chicago).

Phase separation during surface degradation. Do the same processes occur when the hot oil emerges from the seabed?

Angle (2θ)10 20 30 40

Inte

nsity

(cps

)

0

25

50

75

100

Emulsified In Situ Burn

from near Venice, LA

n-napthene

X-Ray Diffractometry

Asphaltene

Implications of work • This study will produce data necessary for

modeling dispersion of hydrocarbons in the deep sea in the presence of dispersants.

UPTAKE AND DISPERSION OF CRUDE OIL FROM WATER USING (R)-N-ALKYL-12-HYDROXYOCTADECYLAMMONIUM

SALTS AND AMMONIUM DITHIOCARBAMATES OF AMINO-SUBSTITUTED POLYSILOXANES

Richard G. Weiss Department of Chemistry Georgetown University

Washington, DC 20057-1227 Email: weissr@georgetown.edu

Background Where we are Future research

Background

N(CH2)nH

H HOH

+Y-

HSnY

xPSil

Si

CH3

CH3

OSi

O

CH2

CH3

1-X XNH3

H3N

HN

H3N

HN

H3NS

S

S

SH3N

NH

H3N

NH3

SS

CH2

CH2

NH2xPSil-S

Mallia, Terech, Weiss J. Phys. Chem. B, 2011, 115, 12401–12414

Yu, Wakuda, Blair, Weiss, J. Phys. Chem. C 2009, 113, 11546-11553

HSN-n-Y

gasoline naphtha xylol 30 min after adding an equal wt of 10PSil-S water (bottom) and

before contact with vial samples appearance of 10PSil-S

after removal from vial samples

Where we are: Gels with xPSil-S

% Swelling (w/w) = [(Wg-Wp)/Wp] х 100%

Where we are: Dispersions with HSN-n-Y ~ 2 mg N-propyl-(R)-12-hydroxyoctadecylammonium salts (HSN-3-Y) in 20-50 mg methanol added to mixture of 100 mg gasoline and ~2.5

g water and agitated by hand

Future research With xPSil-S Measure rates of swelling Measure rates of deswelling Determine mechanism of uptake and loss Investigate different x

With HSN-n-Y Investigate different n Investigate different Y Determine nature of dispersions and changes

over time Correlate nature of dispersions and efficiency

of dispersion formation with n and Y

PERHAPS: PERFORM EXPERIMENTS WITH CRUDE OIL

Compare fresh and salt water results

Effects of Pressure on Surfactant

Micellization

Hank Ashbaugh and Bin Meng

Tulane University

Goal: Examine the effects of pressure on

dispersant micellization using molecular

simulations with an eye toward

understanding roles of surfactant, chemistry

and formulation additives on assembly.

Volume of Assembly

G RT lnCMC

V assembly RT lnCMC

PT

C8E5 in water

Lesemann et al. Langmuir (1998)

Up to 2 miles (324 bar)

Deepwater Horizon ~1 mile

Semi-Submersible

Oil Rig

Partial Molar Volumes

Sodium Decyl

Sulfate

Molar Volume of Assembly

Monomer

Micelle

Kirkwood-Buff Analysis

Head Group Domain

Tail Group Domain

surf kT 1 g r drV

Design on Nanoparticles for Stable

Emulsion Droplets at Subsea Conditions

Department of Chemical Engineering

University of Texas Austin

PI: Keith P. Johnston

Students: Zheng (Eric) Xue, Ki Youl Yoon, Andrew Worthen

Research scientist: Hitesh Bagaria

Bryant, Huh, Nguyen (Petroleum, Geosyst.) Milner (BME), Bielawski (polymer org. chemist) Polymer coatings: interfacial properties CO2 sequestration and EOR

Image reservoirs

Nanoparticles at interfaces in porous media: nanomaterials

synthesis, colloid/interface science with polymer science

q q water

CO2

CO2

water

CO2

water

DOE Frontiers of Subsurface

Energy Security (UT-Sandia)

vdWvdW

Steric

Steric

Objectives

• Design nanoparticles for stabilization of emulsions

– Surface coatings to influence contact angle

– high salinity, range of temperatures

– high pressure and presence of light gases

• Fundamental understanding of emulsion stability as a function of surface coating on nanoparticles

– Relationship to emulsion phase behavior

– Interfacial tension and nanoparticle adsorption at oil/water interface

– Oil/water phase ratio and oil composition to understand inversion

• Emulsion phase type and int. and contact angle at the brine-gas expanded liquid interface (Dickson, Binks, 2004) analogous to water-CO2 system.

• Alkane-water phase diagram of nonylphenol ethoxylate (Igepal co520) undergoes phase inversion from propane to dodecane at 200 bar (McFann and Johnston, 1993).

Influence of oil, temperature and pressure on emulsion phase

behavior and interfacial properties versus nanoparticle coating

Design sulfonate copolymer coated ion oxide nanoparticles to control interfacial properties

FeCl2 & FeCl3

+

sulfonate

Polymer

Nucleation

0

20

40

60

80

100

120

0 100 200 300

Rel

ativ

e V

olu

me

Per

cen

t[%

]

Sizes[nm]

DLS Measurement

Nanoparticlestable

at high salinities

pH6 pH8 growth

• Iron oxide superparamagnetic nanoparticles (primary nanoparticle size ~8 nm) synthesized by hydrolysis of ferrous and ferric chlorides.

• Copolymer influences interfacial properties, eg. PAA and PSS

• Design electrosteric stabilization for seawater conditions

TEM Image

3% NaCl

5% NaCl

Captive CO2 bubble for IFT measurement axisymmetric drop shape analysis: Laplace equation

Known surf. concentration in water

Iron oxide nanoclusters Stabilized with amphiphilic polymer to adsorb strongly at the oil/water interface

oil

water

PAA114-b-PBA26 PAA114-b-PBA67 PAA114-b-PBA38

No emulsion

with PAA coated

Iron Oxide

O/W emulsion with amphiphilic

copolymer coated iron oxide

50 um 50 um 50 um

PAA114-b-PBA26 PAA114-b-PBA38 PAA114-b-PBA67

•Larger hydrophobic portion increases the emulsion droplet sizes

• Amphiphilic polymer stabilizers caused the iron oxide nanoclusters to adsorb

strongly at the oil/water interface

• Long-term dispersion stability (more than 1 month)

O/W

Emulsion

Iron oxide nanoclusters Stabilized with amphiphilic polymer to adsorb strongly at the oil/water interface

Coating γ [mN/m] ΔE [kT]

Dodecane-water 52.8 N/A

PAA114-b-PBA26 25.2 -3.9.E×104

PAA114-b-PBA38 28 -3.5.E×104

PAA114-b-PBA67 30.3 -2.4.E×104

PAA 133-r-PBA44 28.2 -1.2.E×105

PAA No change :too

hydrophilic N/A

IFT of 0.27% coated NPs at oil-water

interface

• Large reductions in ift of up to 27.6 mN/m with 0.27 wt% NPs

• Nanoparticle polymer coating

governs ift reduction

• Strong adsorption energy favors droplet stability

2)0

( aE

a :The particle radius η : The 2-dimensional packing fraction 𝛾o = 52.8 mN/m (Dodecane-Water) 𝛾 : Interfacial tension

Adsorption Energy

00

Objectives

• Design nanoparticles for stabilization of emulsions

– Surface coatings to influence contact angle

– high salinity, range of temperatures

– high pressure and presence of light gases

• Fundamental understanding of emulsion stability as a function of surface coating on nanoparticles

– Relationship to emulsion phase behavior

– Interfacial tension and nanoparticle adsorption at oil/water interface

– Oil/water phase ratio and oil composition to understand inversion

Biodegradable Oil Dispersants (Chris Bielawski, Chem. Dept.)

Modify side chain to optimize

interfacial activity

(R = alkyl, aryl, protected

alcohols, etc.)

Controlled molecular weight

Current producers of polylactide: Cargill Dow LLC, Mitsui Toatsu

Optimize:

• Nanoparticle (clay, SiO2, FexOy) • Polymer structure • Particle size • Degradation ability (surfactant structure)

Biodegradable Polymer Nanoparticles:

Biodegradable Polymers:

Large Scale Synthesis: