The abstract must contain conspicuous acknowledgment of

 SPE-190484-MS 
Oil
Spill Cleaning and Recovery by Polyurethane Sponge Coated with Silane
Molecules

Sagar
dadhich,Lijo P Lalu,Pandit Deendayal Petroleum University
Copyright
2018, Society of Petroleum Engineers

This
paper was prepared for presentation at the SPE International
Conference on Health, Safety, Security, Environment, and Social
Resposibility held in Abu Dhabi, UAE, 16-18 April 2018.

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Abstract

With
oil becoming scarcer and more expensive, The oil and gas industry may
now shift in favour of most neglected area that is cleaning and
recovery of oil from oil spills.Oil spills can be costly for
companies and for the environment. The conventional methods of
cleaning of an oil spill, are use of booms, skimmers Inisitu
Burning, and centrifuges .But these containment and conventional
methods have not been successful as nearly 60000 barrels of oil get
released into water every day. However these methods can be replaced
with polyurethane foams that can help in removing the oil out of
water through sorption. The paper presents an approach to solve this
problem by use of porous material that not only absorbs oil
effectively but also provide a way to recover the spilled oil.It is
believed to have potential to replace present sorbents which are used
commercially.

Introduction

Oil
spills have been considered as one of the most serious disasters that
is threatening the marine ecosystem and human health. Various
processes have been developed to control oil spill, such as the use
of dispersants, skimmers,Activated Charcoal, bioremediation, in- situ
burning or sorbent materials. Among these methods, sorption with
sorbent has been considered to be one of the most effective ways for
oil spill cleaning due to its ability of collection and the complete
removal of oil from oil spill sites .An oil spill occurs when liquid
petroleum hydrocarbon is released into the environment. The term
applies to spills in the ocean or coastal waters, rivers, or on land.

Oil
spills can cause a huge damage to the enviornment plants ,animals and
human beings.It is so because they lead to water pollution which
damages the life of marine species.The oil that is spilled is eaten
by the marine animals and through food chain it reaches to human
beings and animals .There is a huge loss of the natural resources. As
the spilled oil remains unused .

Polyurethanes
are linear polymers which are formed by the addition reaction between
isocyanate and polyols.They contain carbamate groups (-NHCO2). These
carbamate groups so called urethane .When reagents are used in large
quantities polyurethane is formed. It is a superhydrophobic polymer
which shows high oil absorption capability , fast adsorption, easy
recovery from water surface, and no water absorption because of
hydrophobic in nature. The theoretical study shows that the high
surface area of the polyurethane helps in good sorption capacity
which means a large amount of oil can be adsorbed and absorbed . Many
properties of Polyurethane and Silane have been theoretically studied
which makes them stand a chance of replacing the present oil spill
cleanup methods.

The
silane molecules are used to induce the super hydrophobic
transformation..The presented approach will help in making the
process of oil spill cleaning easy along with low costs for
practical applications (Oil Spills).Future oil spills can be very
effectively tackled by the use of Polyurethane sponge coated with
silane molecules

Conventional
Methods for Cleaning Oil Spills

1.Chemical
Methods

Dispersants:
Chemicals, such as detergents, break apart floating oil into
small particles or drops so that the oil is no longer in a layer on
the water’s surface. These chemicals break up a layer of oil into
small droplets. These small droplets of oil then disperse or mix with
the water. The problem with this method is that dispersants often
harm marine life and the dispersed oil remains in the body of water
where it is toxic to marine life (Figure 1)
Figure 1
2.Physical Methods:

Burning:
Burning of oil can actually remove up to 98% of an oil spill.
The spill must be a minimum of three millimetres thick and it must be
relatively fresh for this method to work.There has been some success
with this technique in Canada. The burning of oil during the Gulf War
was found not as large a problem as first thought because the amount
of pollution in the atmosphere did not reach the expected high
levels. Field-testing is needed to check the feasibility of this
technology. (Figure 2)
Figure 2
3.Biological
Methods:

Bioremediation:
There are bacteria and fungi that naturally break down oil.
This process is usually very slow- it would take years for oil to be
removed by microorganisms. Adding either fertilizer or microorganisms
to the water where the spill is located can speed up the breakdown
process. The fertilizer gives the bacteria and fungi the nutrients
they need to grow and reproduce quicker. Adding microorganisms
increases the population that is available to degrade the oil. A
drawback to adding fertilizers is that it also increases the growth
of algae.When the large numbers of algae die they use up much of the
oxygen & hence there isn’t enough oxygen for animals like
fish.act like a fence to keep the oil from spreading or floating
away.
3.Mechanical
Methods:
Booms: Booms float on the surface
and have three parts: A ‘freeboard’ or part that rises above the
water surface and contains the oil and prevents it from splashing
over the top (Figure 3).A ‘skirt’ that rides below the surface
and prevents the oil from being pushed under the booms and escaping.A
cable or chain that connects, strengthens, and stabilizes the boom.
Connected sections of boom are placed around the oil spill until it
is totally surrounded and contained
Figure 3
Skimmers:
Skimmers are used in conjunction with booms. (Figure 4) A
skimmer collects and remove oil from the water surface.Skimmers can
be towed, self propelled, moored in river currents, or even used from
shore.It sucks up more water than oil and it’s preferably used in
calm water.

Figure
4

Principle
of Oil sorption
Sorption
is a process in which absorption and adsorption take place at same
time. Adsorption and Absorption looks similar but there is a huge
difference between them. Adsorption may be defined as the
 accumulation of molecules on a surface in contact with an air
or water phase.Absorption is simply the
 dissolution of molecules within a phase
Adsorption:
Adsorption is a surface phenomenon in which molecules
of an adsorbate concentrates only on the surface of an adsorbent.It
is an Exothermic process in which heat is always released after it
.The concentration of the adsorbate is different in surface and
bulk.There are two types of adsorption.One is Physisorption and other
is chemisorption .In physisorption there are weak vanderwall force of
attraction whereas Chemisorption involves strong chemical bond.

Absorption:Absorption
is a bulk phenomenon in which an absorbate completely penetrates into
the body of a solid or liquid to form a compound or a solution.It is
a Endothermic process. Concentration of the absorbate is constant
throughout the material .It takes place at uniform rate

Sorbents:
Sorbents are the materials in which both
adsorption and absorption take place.This property helps in removal
of oil from water as both phenomenon are happening at the same
time.They have large surface area .

Proposed
solution and synthesis
A sorbent can
be designed which will soak only oil without absorbing water.
Sorbents are insoluble materials or mixtures of materials used to
recover liquids through the mechanism of absorption, or
adsorption, or both To be useful in combating oil spills,
sorbents need to be both Oleophilic (oil-attracting) and hydrophobic
(water-repellent). Other Properties Include: high uptake capacity,
high rate of uptake of oil , buoyancy, retention over time,
durability in aqeous medium, reusability , biodegradability and
recovery of oil. So polyurethane (PU)foam can be used as an sorbent
as it satisfies all properties required to be a good Oil spill
cleanup sorbent. For manifesting hydrophobicity and oleophilicity
nano-particles can be coated.

First
polymer foams were made in 1935’s and -45’s,in which foamed
polystyrene was the first polymer foam in 1930s.Sir Otto Bayer was
responsible for the creation of polyurethane polymer.Polyurethane
replaced rubber after its invention because of good resistive
properties and It was economical also as compared to Rubber .Due to
its light weight it was also used as a coating agent

Polyurethanes
are any type of polymer containing a urethane linkage.The urethane
linkage is -NH-CO-O-. The way to form polyurethanes is done by
reacting isocyanates with compounds that have an active hydrogen,
such as diols, that contain hydroxyl groups, in the presence of a
catalyst. Since there are many compounds containing active hydrogens
and many different diisocyanates, the number of polyurethanes that
can be synthesized is also large. The specific properties of the
polyurethane can be tailoredto a specific need by combining the
appropriate compounds.The large surface area helps in more
sorption.(Figure 5)

Source:ResearchGate
Figure
5

The
synthesis of this sponge involves 3 major steps:

1:Synthesis
of polyurethane by reaction between disiocynate and dialchol.
2:synthesis
of magnetic silane by stober method.
3:Sequential
Infiltration Synthesis of magnetic silane to polyurethane
Polyurethane
Synthesis
Polyurethanes
are the polymers which are made by the addition reaction of
isocyanates and polyols in the presence of appropriate temperature
and pressure .Care has to be taken in performing the synthesis as
cyanate is involved in the reagent side which is very toxic. When
there are two functional groups it’s termed a diisocyanate and diol
.The reaction leads to formation of polyurethane which is mainly
Constituting the amide group.

Silane
synthesis
Coating of Fe3O4 nanoparticles by silica can be
achieved according Stöber method that consists of the hydrolysis and
condensation of a silica precursor, such as tetraethyl orthosilicate
(TEOS)

Sequential infiltration synthesis
is used to create sponges to soak up oil spills

SIS is a form of atomic layer
deposition (ALD) in which a polymeric material (e.g., polyurethane)
is infused with inorganic material. In the case of the Oleo Sponge,
the inorganic material is a metal oxide. The metal oxide is a
substrate for an oleophilic (oil-loving) substance(ANL LABORATORY)
Sequential Infiltration Synthesis
allows the coating of nooks and crannies of the foam with aluminium
oxide. The aluminium oxide serves as a base coat on which
Nanoparticle-silane can be deposited

Properties
The theoretical
and experimental studies have shown that the Polyurethane sponge can
Absorb upto 90 times its own weight in oil(only oil no water) The
Water contact angle rated greater than 125 degree means that it is
strongly oil wet which means it will show Excellent hydrophobicity
and oleophilicity.

Source:IIT Kanpur,Virtual
Laboratory
It is lighter
than water so Remains afloat when saturated with oil for months Most
important property is that they are Reusable ,so economically viable.
Performs equally well with mixture of different crude oils.Due to
elasticity both the oil absorbed and polyurethane sponge can be
reused. It is buoyant,Resilient, moisture resistance and durable
.They are Thermally stable(can work in both high and low temperature)
so can be used in any environment and their property will not change
during contact with sunlight. The material is biologically and
chemically inert( it’s resistant to fungal growth and insect), to
fungal growth and insect),so no chances of corrosion

How
does Sponge Works
The
major working principle of this is that It attracts Oil
,preferentially than water, i.e. It should act both hydrophobic and
oleophilic.The oil is preferentially absorbed to the surface of the
foam  and water molecules are repelled by the surface.So when
the thin sheets of PU foam coated with magnetic silane the oil gets
absorbed and after some time the foam absorbs whole oil and only
water is left alone.The oil Uptake is very very large as compared to
water uptake .Oil difffuse into the matrix of PU foam by a process
similar to capillary action,causing it to combine with the material
as it will not leak out or can ‘t be squeezed out under
pressure.The large surface area helps in rapid absorption

Source:ScienceDirect
Initially
prolonged water is squirt on the sponge. Consider blue color as oil
and white color as water.Now as the sponge is hydrophobic and
oleophilic so sponge will not wet water but will wet oil. So
gradually the sponge is wetted by the blue color and water remains
afloat .
Economic
Viability
As
our whole oil and gas industry rely on the economics that is the net
present value must be greater than zero,it is important that the
methods which we use should be economical.The Polyurethane sponge
used is very economic and environmental friendly.
Foam sheets costs $80 to $165. Every year 706 million gallons
of oil is wasted in the form of spills. It means that $840 million is
lost every year. The Lifespan of a polyurethane foam is approximately
25 years. $12.5 billion was the cost in the cleaning process of oil
spill in Gulf of Mexico .$34 billion was the cost in the cleaning
process of oil spill in coral sea,Queensland, Australia. Xingang
port, China $50 million.Therefore, the PU foam is having a great
economic viability as compared to conventional methods

Enviornmental
Discussion

Polyurethane foams are light in weight so they remain
afloat in water so less chances for the marine organism to get
affected .Polyurethane foams are non toxic and non inflammable.
Previously they had the disadvantage that during their synthesis they
release harmful chemicals which pollute the enviornment and cause
damage to humans and animals as they suffered from asthama and eye
damage but Now a days,It is made by using in part renewable
natural resources i.e. polyols(from  petroleum is replaced by
polyols made from soybean, castor, sunflower or a mix of all. So It
becomes biodegradable and does not have any toxicity.

Conclusion
The
use of Polyurethane Foam coated with silane can be a good alternative
for oil spill cleanup as compared to current conventional methods
used in the oil and gas industry.The sponge has lot of advantages and
properties which make them unique and a good substitute for oil spill
cleanup method. Nanoparticles have that capability that many renowned
process have not been capable to do so that is cleaning of oil
spills. They have superior properties which can
help in cleanup of oil spills.May be one day when oil spill
occurs ,we can scatter these nanoparticles and they will absorb oil
Quickly without damaging the environment. At the same time these can
cause negative impact on animal health ,if they are not properly
removed from the sea or the place where oil spill has taken place.

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