Synthesis and Application of Visible Light
Active Photocatalysts in Oil Spill Remediation
Systems
Dr. Emmanuel Nyankson
Department of Materials Science and Engineering, University of Ghana, Legon-Accra Department of Materials Science and Metallurgy, University of Cambridge
([email protected] , [email protected] )
Collaborator: Prof. Vasant R. KumarDepartment of Materials Science and Metallurgy, University of Cambridge
1
Gulf of Mexico Oil Spill 2010
2
Killed 5 workers
200 million gallons of
crude oil released into
the Gulf of Mexico
Oil Spills on the African Continent
3
• 250 000 gallons of crude oil • 699 barrels of oil mud
www.ghana.gov.gh/index.php/media-center/features/3836-ten-years-of-oil-exploration-has-ghana-any-oil-spill-contingency-plan-in-place
Environmental Impact of Oil Spills
Effect on aquatic species
Effect on vegetation and beaches
www.wikipedia.com4
Mechanical
containment and
collection
In situ burning
Chemical
dispersants
Shoreline
cleanup
Natural
biodegradation
(no action)Mo
st c
om
mon o
il s
pil
l re
med
iati
on o
pti
ons
Expensive and
environmentally
harmful
Natural processes
are slow and may
allow the oil to
come ashore
Leads to
significant air
pollution
Unfeasible for
large oil spills
Dispersants are one of the few
options for minimizing the
impact of a large oil spill at sea.
Oil Spill Remediation
National Research Council (NRC). Using Oil Spill Dispersants on the Sea, 1989.
5
Dispersants are liquid blends of surfactants, hydrocarbon-based solvents,
and additives.
The active ingredient of dispersants is a surfactant, which is an amphiphilic
molecule that possesses both hydrophilic and hydrophobic parts.
o Example of surfactants used in dispersants:
Sodium dioctyl sulfosuccinate (DOSS)
Hydrophobic tail
Hydrophilic
head
SurfactantOrientation at
the interface
Dispersant Chemistry
Fiocco, R. J. et al. Pure and Applied Chemistry, (1999) ; Kujawinski, E. B. et al. Environmental Science & Technology, (2011)
Hydrophobic tail
Hydrophobic tail
Hydrophilic head
Application of energy
oil-in-water
emulsion
6
Dispersant
Hydrocarbon Based
Solvent
Surfactants
Degrade Aliphatic
Components in Crude
Oil
o Environmentally benign solvent e.g,
water
o Solvent free dispersant e.g.,
surfactants loaded onto HNT
o Natural surfactants e.g, Saponin
o Food grade surfactants e.g., Lecithin
o Combined Photodegradation and
biodegradation System
Strategies to Overcome Current Challenges
7
water
oil
Dispersant composite particles with dissolvable matrix allows for the
selective release of surfactant within an oil spill.
Advantages of surfactant microcapsules:
o Eliminate the need for hydrocarbon-based solvents
o Reduce surfactant wastage
o Minimize the amount of surfactant needed
Dispersant Composite Particles
Dispersant composite
particles can be stored as
powder and delivered by
slurry via :
o Aircrafts
o Wellhead application
with nozzles.
Surfactant (DOSS)
Dissolvable matrix
(paraffin wax)
Sea water
DOSS not released
Paraffin wax dissolves
DOSS is
released
Microparticles orient at
the oil-water interface
8Nyankson et al., Ind. Eng. Chem. Res., 2014, 53 (29), pp 11862–11872Nyankson et. al., Water Air Soil Pollution (2016) 227: 29.
Food Grade Surfactant
9
Soybean Lecithin
Nyankson et al., ACS Sustainable Chem. & Eng., 2015, 3 (5), pp 920–931;Nyankson et al., ACS Sustainable Chem. & Eng. 2016, 4(4), pp 2056-2067.Efavi et al. ACS Ind. Eng. Chem. Res., 2017, 56 (44), pp 12608–12620
Halloysite Nanotubes in Dispersant Formulations
10Owoseni and Nyankson et al., Journal of Colloid and Interface Science 463 (2016) 288–298
Owoseni and Nyankson et al., Langmuir, 2014, 30 (45), pp 13533–13541Nyankson et al., Ind. Eng. Chem. Res., 2015, 54 (38), pp 9328–9341
Halloysite Nanotube (HNT) Naturally formed and composed of double layer of Al, Si,
H and O. Ultra-tiny hollow tubes with diameters smaller than 100
nm and length ranging from 500 nm to 1.5 micrometers.
Photocatalysis for Oil Spill Remediation
11
Solar Insolation
Photocatalysis
Photocatalysis is effective in degrading aromatic components in
crude oil while biodegradation is effective on aliphatic components.
Photocatalysis for Oil Spill Remediation: Ag-Ag3PO4
12
AgNO3
Na2HPO4Formaldehyde
Ag-Ag3PO4 Ag3PO4
Photocatalysis for Oil Spill Remediation : Ag-Ag3PO4
13
Ag
300 400 500 600 700 8000
20
40
60
80
100
Ref
lect
an
ce (
%)
Wavelength (nm)
Ag3PO4
Ag-Ag3PO4
450 500 550 600 6500.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Ab
so
rban
ce
Wavelength (nm)
0 min
2 min
4 min
6 min
8 min
10 min
450 500 550 600 6500.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Ab
so
rba
nc
e
Wavelength (nm)
0 min
1 min
2 min
3 min
4 min
5 min
Ag3PO4Ag-Ag3PO4
Photocatalysis for Oil Spill Remediation : Ag-Ag3PO4
14
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Ag3PO4 Ag-Ag3PO4
Rate
Con
stan
t (K
/min
)
240 255 270 285 3000.00
0.05
0.10
0.15
0.20
Ab
sorb
an
ce
Wavelength (nm)
0 min
30 min
60 min
90 min
120 min
200 300 400 500 6000.0
0.5
1.0
1.5
2.0
2.5
3.0
Ab
so
rban
ce
Wavelength (nm)
0 min
15 min
30 min
45 min
60 min
90 min
120 min
280 320 360 400 440 4800.0
0.2
0.4
0.6
0.8
1.0
Ab
sorb
an
ce
Wavelength (nm)
0 min
15 min
30 min
45 min
60 min
90 min
120 min
Anthracene
Pyrene
Naphthalene
Photocatalysis for Oil Spill Remediation : Ag-Ag3PO4
15
photocatalyst surfactant
Collaboration
16
University
of Ghana
The Open
University
University
of
Cambridge
Prof. Vasant R. Kumar
Department of Materials Science and
Metallurgy, University of Cambridge
Dr. Satheesh Krishnamurthy
School of Engineering and Innovation
The Open University
Collaboration and Training
17
Summary
18
• Ag-Ag3PO4 has potential application in oil spill remediation.
• A combined photo degradation and biodegradation system for oil
spill remediation can be developed from halloysite nanotubes,
surfactants and photocatalysts.
• The CAPREx fellowship has:
• enabled me to establish collaboration with researchers in other
Universities.
• improved my academic research and professional development.
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