Field of Invention

Water is removed from oil using hydrophil ic paramagnetic or superparamagnetic nanoparticles.

Background of the Invention

Water in oil affects the oil's base-stock value and may lead to oxidation, viscosity increase via emulsification and foaming .

Water can exist in oil in three states or phases. The first state, known as dissolved water, is characterized by individual water molecules dispersed throughout the oil. Oil can contain a significant concentration of dissolved water with no visible indication of its presence. Most industrial oils such as hydraulic fluids, turbine oils, etc., can hold 200 to 600 ppm of water in the dissolved state depending on the temperature and age of the oil, with aged oils capable of holding three to four times more water in the dissolved state than fresh oil.

Once the amount of water has exceeded the maximum level for it to remain dissolved, the oil is saturated. At this point, the water is suspended in the oil in microscopic droplets known as an emulsion.

The addition of more water to an emulsified oil/water mixture will lead to a separation of the two phases producing a layer of free water as well as free and/or emulsified oil. For oils whose specific gravity is less than 1 .0, this free water layer is found on the bottom of tanks and sumps. The amount of water a specific oil type can dissolve varies significantly, depending on e.g. the base oil, additives, oxidation, temperature and pressure.

Surveys have documented that water or moisture is the second largest contamination (after solid particles) in oil systems. Moreover, water has a damaging effect on the life time of oil and system components due to corrosion if oil is present in the water.

There are different ways to remove water from oil :

• Gravity Separation • Centrifuge - Spinning Oil Clean

• Absorption Removal

• Vacuum the Oil Dry

• Dehydration by Air Stripping

• Heating the Oil Dry

• Adding chemical demulsifiers

EP2244268A1 is directed to nanoparticles consisting of a shell and one or more magnetic cores wherein said magnetic core consist of a ferromagnetic, ferromagnetic or superparamagnetic material coated with one or more graphene layers and wherein said shell consists of an oxidic glass composition .

WO201 21 1 5814 is directed to method for oil removal in biphasic oil/water systems comprising : adding to oil a magnetisable material of micron size and with no net magnetization to form a magneto-rheological fluid; and magnetically attracting the magneto-rheological fluid to separate the oil and water phases.

US201 001 5059 relates to nanoparticles comprising a maghemite (Fe2Os) core and a shell of polyethylene oxide, as well as a method of preparation thereof. US201 001 5059 discloses these particles to be of relevance for certain medical treatments involving the injection of particles into the blood of a patient such as MRI contrast agents.

Summary of the Invention

The invention is directed to a method of removing water from oil comprising contacting the oil with hydrophil ic paramagnetic or super-paramagnetic nanoparticles so as to provide a water depleted oil . Typically, the hydrophil ic nature of the nanoparticles is due to an at least partial coat of a hydrophilic polymer.

One aspect of the invention is directed to a method for removing water from oil comprising contacting the oil with a hydrophil ic paramagnetic or

superparamagnetic nanoparticle being at least partially coated with a

hydrophilic polymer so as to provide water-depleted oil .

According to any embodiment of the first aspect, the method can comprise the following steps: i) Contacting an oil with paramagnetic or superparamagnetic nanoparticles coated with a hydrophilic polymer,

ii) Complexing at least a portion of the water in said oil with the nanoparticle so as to form a water-nanoparticle complex;

iii) Removing the water-nanoparticle complex from the oil by applying a

magnetic field so as to provide oil with depleted water content.

According to any embodiment of the first aspect, the coating of the

nanoparticles is partial or whole and at least 1 0% of the surface atoms of the nanoparticles are conjugated to a hydrophilic polymer.

According to any embodiment of the first aspect, the oil is selected from the group consisting of crude oil, refined oil, motor oil or lubrication oils.

According to any embodiment of the first aspect, the diameter of the

superparamagnetic or paramagnetic particles is in the range of 1 -500 nm, such as in the range of 3-500 nm, or in the range of 5-300 nm, such as in the range of 7.5-200 nm, typically in the range of 1 0-1 00 nm, or in the range of 1 5-50 nm.

According to any embodiment of the first aspect, the superparamagnetic or paramagnetic nanoparticles are made from iron, gold, silver, palladium, nickel or cobalt, or alloys thereof.

According to any embodiment of the first aspect, the superparamagnetic or paramagnetic nanoparticles are magnetite (Fe3O ₄ ) nanoparticles.

According to any embodiment of the first aspect, the hydrophilic polymer is selected from the group consisting of polyethylene glycol, polyvinyl alcohol, hexapropylmethylene glycol, polyacrylamide, polyacrylic acid,

polymethacrylate, polymethyacrylic acid, poly (N-isopropylacrylamide,

polyethylenimine, poly(2-oxazoline), poly(ethylene oxide), poly

(vinylpyrrol idinone), poly(styrenesulfonate), polyethers, poly(methyl vinyl ether), and copolymers thereof.

According to any embodiment of the first aspect, the hydrophilic polymer is selected from the group consisting of polyethylene glycol , polyvinyl alcohol, hexapropyl methylene glycol, polyacrylamide and copolymers thereof. According to any embodiment of the first aspect, the oil from which water is to be removed comprises water as microscopic water droplets i .e. an emulsion or dissolved water, particularly dissolved water.

According to any embodiment of the first aspect, a crude oil might be subjected to treatment according to any embodiment of the first aspect, resulting in a dissolved water content of less than 1 wt% water/oil .

According to a further aspect, the invention relate to an oil obtainable by the any embodiment of the first aspect.

According to yet a further aspect, the invention relates to use of paramagnetic or superparamagnetic nanoparticles for the removal of water from an organic fuel product according any embodiment of the first aspect. The organic fuel product can be a crude oil, a refined oil, a motor oil, or a lubricant oil .

Brief Description of Figures

Figure 1 depicts the treatment of oil comprising water in a preferred

embodiment of the invention . Nanoparticles coated with a hydrophilic polymer are added to the oil to be depleted in water content. Water molecules bind to the hydrophilic polymer followed by removal of the hydrated nanoparticles by applying a magnetic field so as to provide oil with depleted water content.

Detailed Description

An object of the invention is a crude oil having a water content of less than 1 wt% in oil . The invention is directed, however, to any oil obtainable by the method defined herein .

The inventors have developed a method of removing water in oil comprising contacting the oil with hydrophilic paramagnetic or superparamagnetic nanoparticles so as to provide a water depleted oil . Typically, the hydrophil ic paramagnetic or superparamagnetic nanoparticles are paramagnetic or superparamagnetic nanoparticles at least partially covered by a hydrophilic polymer.

The term "at least partially covered" is intended to mean wherein at least 1 % of the surface atoms making up the surface area of the nanoparticle is covered with a hydrophilic polymer, such as a polymer selected from the group consisting of polyethylene glycol, polyvinyl alcohol, hexapropylmetheylene glycol, polyacrylamide, polyacryl ic acid, polymethacrylate, polymethyacryl ic acid, poly (N-isopropylacrylamide, polyethylenimine, poly(2-oxazoline), poly(ethylene oxide), poly (vinylpyrrolidinone), poly(styrenesulfonate),

polyethers, poly(methyl vinyl ether), and copolymers thereof. Typically, at least 1 0% of the surface atoms making up the surface area of the nanoparticles is covered with a hydrophilic polymer, such as at least 20%, at least 30%, at least 40%, such as at least 50% or 60% of the surface atoms making up the surface area of the nanoparticles is covered with a hydrophilic polymer

A further aspect of the method of the invention is directed to depleting the water content of the oil to below 1 wt%, comprising contacting the oil with hydrophil ic paramagnetic or superparamagnetic nanoparticles so as to provide a water depleted oil . The oil to which the nanoparticles are added may be an oil-water emulsion, may comprise a water layer, may water droplets and/or may comprise dissolved water. In an interesting embodiment of the invention, the oil

comprises only water droplets of water and/or only dissolved water, particularly only dissolved water. Advantageously, the method of the invention is suitable to remove dissolved water from the oil . Various commercial applications of the method are equally appl icable to oil-water emulsions and/or to oil having a water layer.

The invention is directed to a method of removing water from oil comprising contacting the oil with hydrophil ic paramagnetic or superparamagnetic

nanoparticles so as to provide a water depleted oil . Typically, the hydrophil ic nature of the nanoparticles originates from at least partial coating of a

hydrophilic polymer.

The method of the invention typically comprises

i) Contacting an oil with paramagnetic or superparamagnetic nanoparticles coated with a hydrophilic polymer,

ii) Complexing at least a portion of the water in said oil with the nanoparticle so as to form a water-nanoparticle complex;

iii) Removing the water-nanoparticle complex from the oil by applying a

magnetic field so as to provide oil with depleted water content. The method of the invention is applicable to oil in general , such as oil selected from the group consisting of crude oil, refined oil , motor oil or lubrication oils, typically crude oil or refined oil .

The diameter of the hydrophil ic superparamagnetic or paramagnetic particles is between 1 nm - 1 0 μητι, preferably in the range of 1 - 1 000 nm. In a suitable embodiment, the particle size of the nanoparticles is in the range of 1 -500 nm, such as in the range of 3-500 nm, preferably in the range of 5-300 nm, such as in the range of 7.5-200 nm, typically in the range of 1 0-1 00 nm, more preferably in the range of 1 5-50 nm .

Nanoparticles with a diameter in the nanoscale have a large area-to-volume (given by 6/c/, c/=diameter) and hence a pool of small nanoparticles can have a very large total surface area.

The method involves the use of superparamagnetic or paramagnetic

nanoparticles comprising chemical functional groups. The particles are paramagnetic in nature in that they are attracted to a magnet when placed in a magnetic field but retain no magnetic memory upon removal of the magnetic field . This characteristic prevents aggregation and allows paramagnetic properties. The magnetism of the paramagnetic particle may be for easy dispersion of the particles. Paramagnetic materials include most chemical elements and some compounds, they have a relative magnetic permeability greater or equal to 1 (i.e., a positive magnetic susceptibil ity) and hence are attracted to magnetic fields. The particles may be a composite of a combination of any number of elements or compounds. The particle may be

superparamagnetic or paramagnetic due to the use of an organic

superparamagnetic or paramagnetic compound, a metallic superparamagnetic or paramagnetic compound or an organometallic superparamagnetic or paramagnetic compound .

The magnetism of the superparamagnetic or paramagnetic particle may be due to the particles comprising an element selected from the group consisting of lithium, oxygen, sodium, magnesium, aluminum, calcium, titanium, manganese, iron, cobalt, nickel , strontium, zirconium, molybdenum, ruthenium, rhodium, palladium, tin, barium, cerium, neodymium, samarium, europium, gadol inium, terbium, dysprosium, holmium, erbium, thulium, osmium, tungsten, tungsten iridium, tungsten and platinum. Strong paramagnetism is exhibited by compounds containing iron, palladium, platinum, and the rare-earth elements. Accordingly, the particles preferably comprise an element selected from the group consisting of iron, palladium, platinum, and the rare-earth elements. The hydrophil ic superparamagnetic or paramagnetic nanoparticles may alternatively be selected from materials made from iron, gold, silver, palladium, nickel or cobalt, or alloys thereof. In an interesting embodiment, the hydrophilic superparamagnetic or paramagnetic nanoparticles are magnetite (Fe3O ₄ )

nanoparticles.

The particles may comprise a superparamagnetic or paramagnetic core, optionally at least partially coated with an inorganic or organic compound; or may comprise a composite core of a paramagnetic and a non-paramagnetic compound . The superparamagnetic or paramagnetic particles may be at least partially coated with an organic compound or an inorganic compound .

Hydrophilic polymers are suitable for use as a component of nanoparticle core serving as non-paramagnetic compounds and would be mixed with a

superparamagnetic or paramagnetic material .

Accordingly, a hydrophilic polymer can be used to at least partially coat a superparamagnetic or paramagnetic core or may be used as a composite material in the construct of a a superparamagnetic or paramagnetic core. The hydrophilic polymer may be selected from the group consisting of polyethylene glycol, polyvinyl alcohol, hexapropylmetheylene glycol , polyacrylamide, polyacrylic acid, ploymethacrylate, polymethyacrylic acid, poly (N- isopropylacrylamide, polyethylenimine, poly(2-oxazoline), poly(ethylene oxide), poly (vinylpyrrolidinone), poly(styrenesulfonate), polyethers, poly(methyl vinyl ether), and copolymers thereof. Preferably, the hydrophilic polymer is selected from the group consisting of polyethylene glycol, polyvinyl alcohol,

hexapropylmetheylene glycol, polyacrylamide and copolymers thereof.

The method for removal of water from oil will increase the stock-tank value of the oil due to the lower water content. Super paramagnetic nanoparticles of, e.g . magnetite Fe3O _4, may be easily coated with hydrophil ic polymers such as PEG, PVA or HPMC, which have very high water affinity. The coated particles are suspended in oil with low water content and mixed in a non-metallic or non- magnetisable tank. After incubation, the particles can be pulled out of the solution by applying a static magnetic field that will align all magnetic moments of the particles in the direction of the magnetic flux vector of the applied magnet hence creating an attractive force. When the particles are removed from the solution, the water-depleted and higher-quality oil is transport away from the tank. The water bound to the nanoparticle surface will be removed by applying an oscillating electromagnetic field resulting in transformation of electromagnetic energy into vibrational energy and hereafter into internal energy of the water. When the internal energy exceeds the heat of adsorption the water will leave the surface. Hereafter the 'cleaned' particles can be re-used for another round of water depletion .

A further aspect of the invention is directed to the use of paramagnetic or superparamagnetic nanoparticles for the removal of water from an organic fuel product. Typically, the organic fuel product is a crude oil, a refined oil , a motor oil, or a lubricant oil .

A first aspect of the invention is directed to a method for removing water from oil comprising contacting the oil with a hydrophilic paramagnetic or

superparamagnetic nanoparticle so as to provide water-depleted oil.

A second aspect of the invention is directed to a method for depleting the water content in oil, such as to below 1%, the method comprising contacting the oil with hydrophilic paramagnetic or super-paramagnetic nanoparticles so as to provide water-depleted oil.

According to any embodiment of the first or second aspect, the paramagnetic or superparamagnetic nanoparticles are at least partially coated with a hydrophilic polymer

According to any embodiment of the first or second aspect, relating to a method comprising the following steps:

iv) Contacting an oil with paramagnetic or superparamagnetic nanoparticles coated with a hydrophilic polymer,

v) Complexing at least a portion of the water in said oil with the nanoparticle so as to form a water-nanoparticle complex;

vi) Removing the water-nanoparticle complex from the oil by applying a

magnetic field so as to provide oil with depleted water content. According to any embodiment of the first or second aspect, the coating of the nanoparticles being partial or whole, wherein at least 10% of the surface atoms of the nanoparticles are conjugated to a hydrophilic polymer.

According to any embodiment of the first or second aspect, the oil is selected from the group consisting of crude oil, refined oil, motor oil or lubrication oils.

According to any embodiment of the first or second aspect, the diameter of the superparamagnetic or paramagnetic particles are between 1 nm to 10 μm, preferably in the range of 1 to 1000 nm.

According to any embodiment of the first or second aspect, the particle size of the nanoparticles is in the range of 1-500 nm, such as in the range of 3-500 nm, preferably in the range of 5-300 nm, such as in the range of 7.5-200 nm, typically in the range of 10-100 nm, more preferably in the range of 15-50 nm.

According to any embodiment of the first or second aspect, the

superparamagnetic or paramagnetic nanoparticles are made from iron, gold, silver, palladium, nickel or cobalt, or alloys thereof.

According to any embodiment of the first or second aspect, the

superparamagnetic or paramagnetic nanoparticles are magnetite (FeeO^ nanoparticles.

According to any embodiment of the first or second aspect, a hydrophilic polymer can be selected from the group consisting of polyethylene glycol, polyvinyl alcohol, hexapropylmethylene glycol, polyacrylamide, polyacrylic acid, ploymethacrylate, polymethyacrylic acid, poly (N-isopropylacrylamide,

polyethylenimine, poly(2-oxazoline), poly(ethylene oxide), poly

(vinylpyrrolidinone), poly(styrenesulfonate), polyethers, poly(methyl vinyl ether), and copolymers thereof. The hydrophilic polymer can be selected from the group consisting of polyethylene glycol, polyvinyl alcohol,

hexapropylmetheylene glycol, polyacrylamide and copolymers thereof.