SPE-190484-MS OilSpill Cleaning and Recovery by Polyurethane Sponge Coated with SilaneMolecules Sagardadhich,Lijo P Lalu,Pandit Deendayal Petroleum UniversityCopyright2018, Society of Petroleum EngineersThispaper was prepared for presentation at the SPE InternationalConference on Health, Safety, Security, Environment, and SocialResposibility held in Abu Dhabi, UAE, 16-18 April 2018.Thispaper was selected for presentation by an SPE program committeefollowing review of information contained in an abstract submitted bythe author(s). Contents of the paper have not been reviewed by theSociety of Petroleum Engineers and are subject to correction by theauthor(s). The material does not necessarily reflect any position ofthe Society of Petroleum Engineers, its officers, or members.
Electronic reproduction, distribution, or storage of any part of thispaper without the written consent of the Society of PetroleumEngineers is prohibited. Permission to reproduce in print isrestricted to an abstract of not more than 300 words; illustrationsmay not be copied. The abstract must contain conspicuousacknowledgment of SPE copyright.AbstractWithoil becoming scarcer and more expensive, The oil and gas industry maynow shift in favour of most neglected area that is cleaning andrecovery of oil from oil spills.Oil spills can be costly forcompanies and for the environment.
The conventional methods ofcleaning of an oil spill, are use of booms, skimmers InisituBurning, and centrifuges .But these containment and conventionalmethods have not been successful as nearly 60000 barrels of oil getreleased into water every day. However these methods can be replacedwith polyurethane foams that can help in removing the oil out ofwater through sorption. The paper presents an approach to solve thisproblem by use of porous material that not only absorbs oileffectively but also provide a way to recover the spilled oil.It isbelieved to have potential to replace present sorbents which are usedcommercially.IntroductionOilspills have been considered as one of the most serious disasters thatis threatening the marine ecosystem and human health. Variousprocesses have been developed to control oil spill, such as the useof dispersants, skimmers,Activated Charcoal, bioremediation, in- situburning or sorbent materials. Among these methods, sorption withsorbent has been considered to be one of the most effective ways foroil spill cleaning due to its ability of collection and the completeremoval of oil from oil spill sites .
An oil spill occurs when liquidpetroleum hydrocarbon is released into the environment. The termapplies to spills in the ocean or coastal waters, rivers, or on land.Oilspills can cause a huge damage to the enviornment plants ,animals andhuman beings.It is so because they lead to water pollution whichdamages the life of marine species.
The oil that is spilled is eatenby the marine animals and through food chain it reaches to humanbeings and animals .There is a huge loss of the natural resources. Asthe spilled oil remains unused . Polyurethanesare linear polymers which are formed by the addition reaction betweenisocyanate and polyols.
They contain carbamate groups (-NHCO2). Thesecarbamate groups so called urethane .When reagents are used in largequantities polyurethane is formed.
It is a superhydrophobic polymerwhich shows high oil absorption capability , fast adsorption, easyrecovery from water surface, and no water absorption because ofhydrophobic in nature. The theoretical study shows that the highsurface area of the polyurethane helps in good sorption capacitywhich means a large amount of oil can be adsorbed and absorbed . Manyproperties of Polyurethane and Silane have been theoretically studiedwhich makes them stand a chance of replacing the present oil spillcleanup methods.
Thesilane molecules are used to induce the super hydrophobictransformation..The presented approach will help in making theprocess of oil spill cleaning easy along with low costs forpractical applications (Oil Spills).Future oil spills can be veryeffectively tackled by the use of Polyurethane sponge coated withsilane moleculesConventionalMethods for Cleaning Oil Spills 1.ChemicalMethodsDispersants:Chemicals, such as detergents, break apart floating oil intosmall particles or drops so that the oil is no longer in a layer onthe water’s surface. These chemicals break up a layer of oil intosmall droplets. These small droplets of oil then disperse or mix withthe water.
The problem with this method is that dispersants oftenharm marine life and the dispersed oil remains in the body of waterwhere it is toxic to marine life (Figure 1)Figure 12.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 berelatively fresh for this method to work.There has been some successwith this technique in Canada. The burning of oil during the Gulf Warwas found not as large a problem as first thought because the amountof pollution in the atmosphere did not reach the expected highlevels. Field-testing is needed to check the feasibility of thistechnology. (Figure 2)Figure 23.BiologicalMethods: Bioremediation:There are bacteria and fungi that naturally break down oil.
This process is usually very slow- it would take years for oil to beremoved by microorganisms. Adding either fertilizer or microorganismsto the water where the spill is located can speed up the breakdownprocess. The fertilizer gives the bacteria and fungi the nutrientsthey need to grow and reproduce quicker. Adding microorganismsincreases the population that is available to degrade the oil. Adrawback to adding fertilizers is that it also increases the growthof algae.
When the large numbers of algae die they use up much of theoxygen & hence there isn’t enough oxygen for animals likefish.act like a fence to keep the oil from spreading or floatingaway.3.MechanicalMethods:Booms: Booms float on the surfaceand have three parts: A ‘freeboard’ or part that rises above thewater surface and contains the oil and prevents it from splashingover the top (Figure 3).A ‘skirt’ that rides below the surfaceand prevents the oil from being pushed under the booms and escaping.
Acable or chain that connects, strengthens, and stabilizes the boom.Connected sections of boom are placed around the oil spill until itis totally surrounded and containedFigure 3Skimmers:Skimmers are used in conjunction with booms. (Figure 4) Askimmer collects and remove oil from the water surface.Skimmers canbe towed, self propelled, moored in river currents, or even used fromshore.It sucks up more water than oil and it’s preferably used incalm water.
Figure4 Principleof Oil sorption Sorptionis a process in which absorption and adsorption take place at sametime. Adsorption and Absorption looks similar but there is a hugedifference between them. Adsorption may be defined as the accumulation of molecules on a surface in contact with an airor water phase.Absorption is simply the dissolution of molecules within a phaseAdsorption:Adsorption is a surface phenomenon in which moleculesof an adsorbate concentrates only on the surface of an adsorbent.
Itis an Exothermic process in which heat is always released after it.The concentration of the adsorbate is different in surface andbulk.There are two types of adsorption.One is Physisorption and otheris chemisorption .In physisorption there are weak vanderwall force ofattraction whereas Chemisorption involves strong chemical bond.Absorption:Absorptionis a bulk phenomenon in which an absorbate completely penetrates intothe body of a solid or liquid to form a compound or a solution.It isa Endothermic process. Concentration of the absorbate is constant throughout the material .
It takes place at uniform rate Sorbents:Sorbents are the materials in which bothadsorption and absorption take place.This property helps in removalof oil from water as both phenomenon are happening at the sametime.They have large surface area .Proposedsolution and synthesisA sorbent canbe designed which will soak only oil without absorbing water.Sorbents are insoluble materials or mixtures of materials used torecover liquids through the mechanism of absorption, oradsorption, 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 andrecovery of oil.
So polyurethane (PU)foam can be used as an sorbentas it satisfies all properties required to be a good Oil spillcleanup sorbent. For manifesting hydrophobicity and oleophilicitynano-particles can be coated. Firstpolymer foams were made in 1935’s and -45’s,in which foamedpolystyrene was the first polymer foam in 1930s.Sir Otto Bayer wasresponsible for the creation of polyurethane polymer.Polyurethanereplaced rubber after its invention because of good resistiveproperties and It was economical also as compared to Rubber .Due toits light weight it was also used as a coating agent Polyurethanesare any type of polymer containing a urethane linkage.The urethanelinkage is -NH-CO-O-. The way to form polyurethanes is done byreacting isocyanates with compounds that have an active hydrogen,such as diols, that contain hydroxyl groups, in the presence of acatalyst.
Since there are many compounds containing active hydrogensand many different diisocyanates, the number of polyurethanes thatcan be synthesized is also large. The specific properties of thepolyurethane can be tailoredto a specific need by combining theappropriate compounds.The large surface area helps in moresorption.(Figure 5) Source:ResearchGate Figure5 Thesynthesis of this sponge involves 3 major steps:1:Synthesisof polyurethane by reaction between disiocynate and dialchol.2:synthesisof magnetic silane by stober method.3:SequentialInfiltration Synthesis of magnetic silane to polyurethanePolyurethaneSynthesisPolyurethanesare the polymers which are made by the addition reaction of isocyanates and polyols in the presence of appropriate temperatureand pressure .Care has to be taken in performing the synthesis ascyanate is involved in the reagent side which is very toxic.
Whenthere are two functional groups it’s termed a diisocyanate and diol.The reaction leads to formation of polyurethane which is mainlyConstituting the amide group. SilanesynthesisCoating of Fe3O4 nanoparticles by silica can beachieved according Stöber method that consists of the hydrolysis andcondensation of a silica precursor, such as tetraethyl orthosilicate(TEOS) Sequential infiltration synthesisis used to create sponges to soak up oil spills SIS is a form of atomic layerdeposition (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 asubstrate for an oleophilic (oil-loving) substance(ANL LABORATORY)Sequential Infiltration Synthesisallows the coating of nooks and crannies of the foam with aluminiumoxide. The aluminium oxide serves as a base coat on whichNanoparticle-silane can be depositedPropertiesThe theoreticaland experimental studies have shown that the Polyurethane sponge canAbsorb upto 90 times its own weight in oil(only oil no water) TheWater contact angle rated greater than 125 degree means that it isstrongly oil wet which means it will show Excellent hydrophobicityand oleophilicity. Source:IIT Kanpur,VirtualLaboratoryIt is lighterthan water so Remains afloat when saturated with oil for months Mostimportant property is that they are Reusable ,so economically viable.
Performs equally well with mixture of different crude oils.Due toelasticity both the oil absorbed and polyurethane sponge can bereused. 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 changeduring contact with sunlight. The material is biologically andchemically inert( it’s resistant to fungal growth and insect), tofungal growth and insect),so no chances of corrosionHowdoes Sponge WorksThemajor working principle of this is that It attracts Oil,preferentially than water, i.e. It should act both hydrophobic andoleophilic.The oil is preferentially absorbed to the surface of thefoam and water molecules are repelled by the surface.
So whenthe thin sheets of PU foam coated with magnetic silane the oil getsabsorbed and after some time the foam absorbs whole oil and onlywater is left alone.The oil Uptake is very very large as compared towater uptake .Oil difffuse into the matrix of PU foam by a processsimilar to capillary action,causing it to combine with the materialas it will not leak out or can ‘t be squeezed out underpressure.The large surface area helps in rapid absorption Source:ScienceDirectInitiallyprolonged water is squirt on the sponge. Consider blue color as oiland white color as water.Now as the sponge is hydrophobic andoleophilic so sponge will not wet water but will wet oil.
Sogradually the sponge is wetted by the blue color and water remainsafloat .EconomicViabilityAsour whole oil and gas industry rely on the economics that is the netpresent value must be greater than zero,it is important that themethods which we use should be economical.The Polyurethane spongeused is very economic and environmental friendly.Foam sheets costs $80 to $165. Every year 706 million gallonsof oil is wasted in the form of spills. It means that $840 million islost every year. The Lifespan of a polyurethane foam is approximately25 years.
$12.5 billion was the cost in the cleaning process of oilspill in Gulf of Mexico .$34 billion was the cost in the cleaningprocess of oil spill in coral sea,Queensland, Australia. Xingangport, China $50 million.Therefore, the PU foam is having a greateconomic viability as compared to conventional methods EnviornmentalDiscussionPolyurethane foams are light in weight so they remainafloat in water so less chances for the marine organism to getaffected .
Polyurethane foams are non toxic and non inflammable.Previously they had the disadvantage that during their synthesis theyrelease harmful chemicals which pollute the enviornment and causedamage to humans and animals as they suffered from asthama and eyedamage but Now a days,It is made by using in part renewablenatural resources i.e. polyols(from petroleum is replaced bypolyols made from soybean, castor, sunflower or a mix of all. So Itbecomes biodegradable and does not have any toxicity.
ConclusionTheuse of Polyurethane Foam coated with silane can be a good alternativefor oil spill cleanup as compared to current conventional methodsused in the oil and gas industry.The sponge has lot of advantages andproperties which make them unique and a good substitute for oil spillcleanup method. Nanoparticles have that capability that many renownedprocess have not been capable to do so that is cleaning of oilspills. They have superior properties which canhelp in cleanup of oil spills.May be one day when oil spilloccurs ,we can scatter these nanoparticles and they will absorb oilQuickly without damaging the environment. At the same time these cancause negative impact on animal health ,if they are not properlyremoved from the sea or the place where oil spill has taken place.ReferencesFingasM. 1995.
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