1. Application of Graphene-Carbon Nanotube
Aerogels in OilSpill Clean-up
Vedant Makwana1
, Anish Singh2
Applied Petroleum Engineering - Upstream
Petroleum and Earth Sciences Department
University of Petroleum and Energy Studies
Dehradun, India
vedant.makwana@stu.upes.ac.in1
singh.anish2010@gmail.com2
Simran K Singh3
Geo-Informatics Engineering
Petroleum and Earth Sciences Department
University of Petroleum and Energy Studies
Dehradun, India
simranksingh208@gmail.com3
Abstract— To address oil spillage and chemical leakage
accidents, the development of efficient sorbent materials is of
global importance. Spilled oil characterizes a menace to the
aquatic ecosystem and the whole environment in broad-
spectrum and requires timely cleanup. Among all the
obtainable technologies, oil sorption has attracted the most
attention because of its simplicity and high level of
effectiveness. The key for the development of this technology is
convenient fabrication of high-performance oil sorbents that
can be used repeatedly. In this work, a fast microwave
irradiation-mediated approach has been proposed for
manufacturing multiwall carbon nanotube (MWCNTs)–
graphene hybrid aerogels, in which MWCNTs are vertically
anchored on the surface of cell walls of graphene aerogels. The
hybrid monoliths show super hydrophobicity and
superoleophilicity, a large pore volume, a large pore size, and
excellent compressibility, demonstrating outstanding
performance for recyclable oil sorption.
Lightweight materials that are both highly compressible
and resilient under large cyclic strains can be used in cleaning
oil spills. Graphene coated Carbon nanotubes offer a
combination of elasticity, mechanical resilience and low
density, and these properties have been exploited in nanotube-
based aerogels.
This paper proposes the use of Graphene Coated Carbon
Nanotubes Aerogels in Oil Spill Clean-up as a replacement for
of the current bungling technology.
Keywords—Oil Spillage ; Graphene ; Nano-Tubes
I. INTRODUCTION
To address oil spillage and chemical leakage accidents,
the development of efficient sorbent materials is of global
importance. Spilled oil characterizes a menace to the aquatic
ecosystem and the whole environment in broad-spectrum and
requires timely cleanup. Among all the obtainable
technologies, oil sorption has attracted the most attention
because of its simplicity and high level of effectiveness. The
key for the development of this technology is convenient
fabrication of high-performance oil sorbents that can be used
repeatedly. In this work, a fast microwave irradiation-
mediated approach has been proposed for manufacturing
multiwall carbon nanotube (MWCNTs)–graphene hybrid
aerogels, in which MWCNTs are vertically anchored on the
surface of cell walls of graphene aerogels. The hybrid
monoliths show super hydrophobicity and superoleophilicity,
a large pore volume, a large pore size, and excellent
compressibility, demonstrating outstanding performance for
recyclable oil sorption.
Lightweight materials that are both highly compressible
and resilient under large cyclic strains can be used in
cleaning oil spills. Graphene coated Carbon nanotubes offer
a combination of elasticity, mechanical resilience and low
density, and these properties have been exploited in
nanotube-based aerogels.
This paper proposes the use of Graphene Coated Carbon
Nanotubes Aerogels in Oil Spill Clean-up as a replacement
for of the current bungling technology.
II. BYGONE DAYS OF THE CONVENTIONAL TECHNOLOGY
Over the past years numerous solutions have been
proposed for dealing with the problem of oil spills. These
include:
A. Mechanical Containment or Recovery
Mechanical containment or recovery is the primary line
of defense against oil spills. Containment and recovery
equipment includes a variety of booms, barriers, and
skimmers, as well as natural and synthetic sorbent materials.
Booms are floating, physical barriers to oil, made of plastic,
metal, or other materials, which slow the spread of oil and
keep it contained. Skilled teams deploy booms using
mooring systems, such as anchors and land lines. Skimmers
are boats and other devices that can remove oil from the sea
surface before it reaches sensitive areas along a coastline.
Sometimes, two boats will tow a collection boom, allowing
oil to concentrate within the boom, where it is then picked up
by a skimmer. Mechanical containment is used to capture
and store the spilled oil until it can be disposed of properly.

2. However this method has its own drawbacks. These
include:
 It is an expensive and complex method of oil
recovery.
 It is a labour intensive method.
 The recovered oil needs further treatment.
 This method is efficient in selected weather
conditions.
 It requires perennial maintenance.
 This method is incompetent.
B. Chemical Agents Recovery
Chemical and biological methods can be used in
conjunction with mechanical means for containing and
cleaning up oil spills. Dispersing agents and gelling agents
are most useful in helping to keep oil from reaching
shorelines and other sensitive habitats. However, the use of
chemical dispersants for response to oil spills has remained a
controversial subject in many countries, despite the fact that
it is one of the more efficient/proven methods. This is
because:
 Dispersion process moves oil from surface to water
column. This exposes water column & near shore
shallow bottom-dwelling organisms to oil.
 Both dispersants and dispersed oil particles are toxic
to some marine organisms
 Effectiveness of dispersant is dependent on type of oil
spilled, weather conditions & how quickly the
dispersant is applied onto oil slick.
 Heavier oils or highly emulsified oils are less
amenable to successful dispersion.
C. Insitu Burning
In situ burning, or ISB, is a technique sometimes used by
people responding to an oil spill. In situ burning involves the
controlled burning of oil that has spilled from a vessel or a
facility, at the location of the spill.
However, use of this technique leads to the loss of valuable
oil resources.
III. NEED FOR INNOVATIVE TECHNOLOGY
Conventional techniques are not adequate to solve the
problem of massive oil spills. In recent years,
nanotechnology has emerged as a potential source of novel
solutions to many of the world's outstanding problems.
Although the application of nanotechnology for oil spill
cleanup is still in its nascent stage, it offers great promise for
the future. In the last couple of years, there has been
particularly growing interest worldwide in exploring ways of
finding suitable solutions to clean up oil spills through use of
nanomaterials. Graphene coated Carbon-based aerogels have
attracted interest in various fields due to their unique physical
properties, such as low apparent density, porosity, and
specific surface area.
As sorbent materials, graphene/CNT hybrid foam, and
exhibit very high sorption capacities, good recyclability and
environmental friendliness.
IV. BENEFITS OF GRAPHENE CNT TREATMENT
A. Ultralow Density and High Porosity: Because of the
ultralow density, the hybrid structures still exhibit a
high porosity of up to 99%.This increases its oil
absorbing power.
B. Excellent mechanical stability: Graphene, a material
that is very strong and extremely elastic, bouncing back
after being compressed. It can also absorb up to 900
times its own weight in oil and do so quickly.
C. Can work in varied Temperatures: CNT/GA can work
in both high as well as low temperatures, making them
effective in working in different environment, like the
arid and the Polar Regions.
D. High hydrophobicity and Superoleophilicity: Due to its
high affinity towards Oil and Low affinity towards
water, it serves as an effective Oil/Chemical absorbing
agent.(Figure 7)
E. Environment Friendly: As this sponge does not react
with the chemicals and oil, it can simply absorb the oil
and be taken out without harming the marine
environment.
F. Recyclable: The graphene-coated aerogel exhibits no
change in mechanical properties after more than 1X106
compressive cycles, and its original shape can be
recovered quickly after compression release.
V. COMPARATIVE ANALYSIS : GRAPHENE CARBON NANO-
TUBE AEROGELS OVER CNT’S
All nanotube-based foams and aerogels developed so far
undergo structural collapse or significant plastic deformation
with a reduction in compressive strength, when they are
subjected to cyclic strain. Hence, an inelastic aerogel made of
single-walled carbon nanotubes can be transformed into a
super elastic material by coating it with between one and five
layers of graphene nanoplates. The graphene-coated aerogel
exhibits no change in mechanical properties after more than
1 × 106
compressive cycles, and its original shape can be
recovered quickly after compression release.
Moreover, the coating does not affect the structural
integrity of the nanotubes or the compressibility and porosity
of the nanotube network. The coating also increases Young's
modulus and energy storage modulus by a factor of ~6, and
the loss modulus by a factor of ~3. The super elasticity and
complete fatigue resistance of Graphene coated CNTs can be
attributed to the graphene coating strengthening the existing
crosslinking points or ‘nodes’ in the aerogel. (Figure 4)
VI. SYNTHESIS OF GRAPHENE CARBON NANO-TUBE
AEROGELS
First, a functionalized graphene aerogel (FGA) via an
ethylene-diamine-functionalized approach with a high
porosity and large pore sizes was exposed under MWI
(Microwave Irradiation) to give rise to ULGA (Ultralight
Graphene Aerogel).Afterward, ULGA was coated with
ferrocene by impregnating it in an acetone solution of
ferrocene and drying naturally, where π−π interactions
between them can drive the uniform distribution of ferrocene
on ULGA. Lastly, additional MWI was involved to produce
rapid in situ superheating of ULGA, resulting in the
decomposition of ferrocene into iron particles and
cyclopentadienyl, which serve as the catalyst and carbon
source, respectively, for the growth of CNTs, leading to the

3. formation of CNT/GA hybrid structure. A freeze-drying
method that involved freeze-drying solutions of carbon
nanotubes and graphene to create a carbon sponge that can be
adjusted to any shape. (Figure 1)
The other process can be describes, as mechanically
enhanced aerogels of graphene sheets and carbon nanotubes
(CNTs) were prepared via hydrothermal reduction of
graphene oxide and CNTs in the presence of ferrous ions
(FeSO4 solution). The resultant graphene–CNT aerogels
possess a 3-D network of carbon structures containing micro-
sized pores and α-FeOOH nanorods within the matrix.
The synthesis of an ultracompressible, superelastic
aerogel by coating the struts and nodes of a single-walled
carbon nanotube network with one- to few-layer graphene
had been demonstrated. These aerogels are capable of
withstanding significant (>90%) compressive strain without
plastic deformation over many cycles. In addition, they have
a highly porous and conductive structure with very large
specific surface area, properties which are ideal for
supercapacitor applications.
VII. PHYSICAL PROPERTIES OF CNT/GA
The as-prepared CNT/GA aerogel has a very low
apparent density of ca. 0.18 mg/ cm3
, which is much less
than those of the traditional carbon aerogels (100–800
mg/cubic cm) and hydrophobic nano-cellulose aerogels (20–
30 mg /cubic cm).
Because it is porous and highly hydrophobic, it can
adsorb organic solvents and oils—up to 900 times its own
weight. It draws oil out of an oil/water mixture with high
efficiency and selectivity, leaving behind pure water (Figure
2)
A piece of CNT/GA aerogel with a volume of 5.3 cm can
stand stably on top of a dandelion without deforming it
(Figure 3). The CNT/GA aerogel porosity is estimated to be
99%. A single gram of aerogel able to absorb up to 68.8
grams of organic material (such as oil) per second. The
extraordinary heat- and fire-resistance of this material are
particularly noteworthy: repeated treatment with the flame of
a torch caused no changes in its form or inner three-
dimensional pore structure.
VIII.PRACTICALITY IN OIL SPILL CLEAN-UP
The prepared aerogels exhibit outstanding adsorption
performance for the removal of petroleum products, fats and
organic solvents especially under continuous vacuum
regime showing adsorption capacity of 28L of oil per gram
of aerogel.
Graphene, a material that is very strong and extremely
elastic, bouncing back after being compressed. It can also
absorb up to 900 times its own weight in oil and do so
quickly. A very interesting application of this aerogel is in
oil spills – a single gram of aerogel able to absorb up to 68.8
grams of organic material (such as oil) per second. Thus,
pieces of CNT/GA can be used to clean oil spill.
IX. TEST AND DEMONSTRATIONS OF GRAPHENE COATED
CNTS
Due to its low apparent density, excellent mechanical
stability, high porosity, and hydrophobicity
/superoleophilicity, the CNT/GA aerogel is an ideal
candidate for the sorption of oils and other organic
pollutants.
When a small piece of the CNT/GA aerogel was placed
on the surface of oil-water mixtures, the oil layer (dyed with
Sudan III) immediately started shrinking and disappeared
completely after a few minutes (Figure 2). Similarly, when
the CNT/GA aerogel was held to approach phenoxin (also
dyed with Sudan III) under water, the phenoxin droplets were
rapidly absorbed by the aerogel upon contact.
A. Test 1 : Sorption Capacity
To further demonstrate the sorption ability of CNT/GA
aerogel, CNT/GA was tested on the basis of sorption
capacities for different commercial petroleum products (e.g.,
gasoline, diesel oil, pump oil, etc.) and toxic organic solvents
(e.g., bromobenzene, THF, n-hexane, etc.).
The sorption efficiency can be assessed by weight gain,
defined as
Wt %=( Weight after saturated sorption – initial
weight)/initial weight
Study Data
The CNT/GA aerogel showed outstanding sorption
ability for these liquids. In general, the sorption capacities
range from 51 to 139 times the weight of the CNT/GA
aerogel for a variety of oils and organic solvents). The
organics were mainly stored in the macro pores of the
CNT/GA aerogels, so the differences of sorption capacities
were related to the densities of organic liquids.
The sorption capacities of CNT/GA are superior to those
of activated carbon (< 1 times), marshmallow-like
macroporous gels (6–14 times), graphene/α-FeOOH aerogel
(13–27 times), micro-porous polymers (< 33 times), and our
previously reported PDMS-coated carbonaceous nanofiber
aerogel (40–115 times); and CNT sponge (80–180 times).
B. Test 2 : Sorption Kinetics
The sorption kinetics of CNT/GA aerogel to four organic
liquids were investigated. The sorption capacity Qt of each
organic liquid was plotted as a function of the sorption time
(Figure 8).
Study Data
The sorption capacities increase with sorption time until
saturation. The saturation sorption time of low-viscosity
organic solvents (ethanol and phenoxin) is much shorter than
that of high-viscosity oils (soybean oil and diesel oil); the
saturation sorption time of the two organic solvents is less
than 30 s, while it takes more than 900 s to reach saturation
for the two oils.

4. The kinetics can be described by a second-order model
1/Qm-Qt=1/Qm +Kt
Where Q indicates the saturated sorption capacity, Qt is
the amount of sorption at time t, t represents the sorption
time, and K is the sorption constant that is viscosity-
dependent.
The fitting values of Qm are nearly equal to the weight
gains further indicating an excellent agreement between the
sorption kinetics model and experimental data.
C. Test 3 : Sorption of Oil Under Harsh Conditions
In addition to sorbents suitable to face oil leakage
accidents under ambient conditions, there is a need for
materials working effectively.
Under harsh conditions, such as high or low
temperatures, traditional sorbents (such as polyurethane-
based and polyethylene-based materials) cannot be used at
temperatures above 200 degree C, and others will become
very brittle at low temperatures. In this regard, our CNT/GA
aerogel exhibits exceptional features.
To test sorption capacity of Graphene coated Carbon
Nanotube Aerogels under Extreme Temperatures. After
continuous 30 s of such extreme heating, it was immediately
immersed into liquid nitrogen (Liq. N2).
Study Data
When exposed to an ethanol flame, the CNT/GA aerogel
did not support any burning and remained inert (After ca. 30
s of such extreme heating, it was immediately immersed into
liquid nitrogen. No decomposition or material change
occurred; even upon repetition of this treatment for several
times, the shape, volume, and inherent 3D porous structure of
CNT/GA aerogel remained unchanged, demonstrating that
the CNT/GA aerogel can withstand extreme temperatures
and rapid temperature change.
 Further, thermogravimetric analysis (TGA) shows
that the CNT/GA aerogel has a weight loss of less
than 8% at a temperature of up to 850 degree C in N2
and can tolerate a high temperature of approximately
400 o C in air.
 After the CNT/GA aerogel was heated in an ethanol
flame or frozen in N2 for five minutes, it still
exhibited a good mechanical property and supported
at least 500 times its own weight. There was only a
slight difference among the original, burned, and
freezed samples in the compressive strain– stress test
.(Meanwhile, the high and low temperature treatments
had no obvious influence on the hydrophobic and
oleophilic properties of the CNT/GA aerogel. As the
sorption properties are insensitive to temperatures, the
CNT/GA aerogel is considered to be an ideal oil
sorbent for dealing with accidents.
Hot soybean oil (164.7 o
C) and cold ethanol (2103.2 o
C)
are absorbed by the CNT/GA aerogel equally completely as
room temperature. Limited only by the measuring range of
our thermometer, even hotter (e.g., 400 0
C) and colder (e.g.,
2196 o
C) organic liquids were also absorbed by our
CNT/GA aerogel, demonstrating overall excellent
performance over a wide temperature range. These results
indicate that the CNT/GA aerogel can be used in some
special situations, such as oil spillage in the polar zone and
high or low temperature organic solvents leakage accidents,
for which conventional sorbent materials.
X. OIL-UPTAKE AND RECYCLABILITY STUDIES OF THE
CNT/GA AEROGELS
The recyclability of CNT/GA, is in high demand in oil
cleanup applications. The sorbed oils can be easily harvested
by compressing the carbon mat and mechanically extruding
the sorbed oil (Figure 5).
The oil gradually squeezes out from the monolith under
compression. The sorption and desorption processes of
different oils are different, and the recovery percentage by
compression is also viscosity-dependent; ethyl acetate with
the lowest viscosity shows 90% recovery, while the most
viscous pump oil exhibits a recovery of 72% for the first
cycle.
Considering multiple sorption−desorption cycles for
diesel fuel, where 70% of the saturated sorption capacity can
be maintained over many cycles. Surprisingly, the recovery
ratio increases to almost 100% after the second cycle.
Because of the interaction between oils and the monolith,
part of the volume has been occupied by oil, which cannot be
regenerated by mechanical extrusion, but the remaining pores
can be fully utilized in cyclic applications. Thus, the full
reclaim of sorbed oils is shown after the first cycle.
XI. CONCLUSION
 In summary, we have developed a novel and simple
method to fabricate macroscopic CNT/GA aerogels
composed of interconnected 3D networks of nanofibers
on a large scale. The CNT/GA aerogel possesses unique
physical features, such as low apparent density, high
porosity, excellent mechanical stability, high
hydrophobicity and superoleophilicity.
 As an oil sorbent, the CNT/GA aerogel exhibits high
sorption capacity, excellent recyclability and high
selectivity.
 Importantly, the sorption performance of the CNT/GA
aerogel can be maintained over a wide temperature range,
from liquid nitrogen temperature up to ca. 400o
C, which
extends its potential applications.

5. XII. TABLES AND FIGURES
Figure 1: Synthesis of Graphene coated Carbon Nanotube Aerogels
Figure 2:( a) the sequential photographs of the CNT/GA Aerogel absorbing diesel oil on water surface. (b) Sorption capacities of CNT/GA
aerogels for various organic liquids in terms of weight gain. (c) Schematic diagram of the CNT/GA aerogel recycling process by heat treatment
method. (d) The sorption recyclability of CNT/GA aerogel over ten cycles.

6. Figure 3: A graphene carbon nanotube aerogels placed on a flower
Figure 4: Graphene coated nanotube aerogel Vs Nanotube Aerogel
Figure 5: Recyclability of Graphene Carbon Nanotube Aerogels

7. Figure 6: High-magnification images for Graphene Carbon Nanotube Aerogels
Figure 7: Water droplets as quasi-sphere and soybean on the surface of

8. CNT/GA
Figure 8: Sorption kinetics of four organic liquids: (a) ethanol, (b) phenoxin, (c) soybean oil, and (d) diesel oil.
Figure 9: Microstructure of graphene-coated single-walled carbon nanotube aerogels.

9. Table 1: Pore volumes of CNT/GA aerogels calculated from the uptake of various organic liquids.
Weight gain (g g-1
) Density (g cm-3
) Pore volume (cm3
g-1
)
Gasoline 61.14 0.73 84.33
Diesel oil 74.82 0.83 89.87
Pump oil 86.34 0.87 99.24
Sesame oil 92.92 0.92 89.84
Soybean oil 90.19 0.93 97.37
Ethanol 71.47 0.79 90.47
Bromobenzene 124.55 1.5 83.03
Chloroform 120.17 1.5 80.11
Phenoxin 139.08 1.6 86.93
THF 78.94 0.89 88.70
n-hexane 51.55 0.66 78.18
Acetone 71.24 0.8 89.05
Table 2: Fitting parameters of sorption kinetics of four organic liquids. Table 3: Fitting parameters of sorption kinetics of four organic liquids.
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Organic liquids K (s-1
) Qm (%)
Ethanol 1.1063×10-2
7285.5
Phenoxin 1.7648×10-2
13827
Diesel oil 2.0669×10-4
7712.0
Soybean oil 5.3708×10-4
8893.2