MX2013000552A - Method for obtaining a porous polymeric material for absorbing oil and some derivatives thereof in aqueous spills. - Google Patents

Abstract

The absorbent materials are attractive for some applications due to the possibility of completely recollecting the oil from the polluted site. The addition of absorbents in zones polluted with oil generates a phase change from solid to semisolid, once this change has been performed, the removal of the oil by means of removing the absorbent is much easier. Ina addition, these materials may be recycled, in some cases. The present invention refers to the obtention of a polymeric material that includes a mixture of a-cellulose and a synthetic copolymer of a high molecular weight obtained by polymerization by the diffusion of styrene and butyl acrylate. Said material has the ability to absorb high amounts of crude oil. In the particular case of crude oil in aqueous spills, the material is efficient since it is highly hydrophobic and porous. The material may be applied in a powder form and has the characteristic of acting as a binding agent; also, at the end of the absorption, the material would able to float over the aqueous surface, this may facilitate the easy removal thereof. Another advantage of the material is that it is formed by a high percentage of completely biodegradable material, which turns it into an environmentally friendly product.

Description

METHOD FOR OBTAINING A POROUS POLYMERIC MATERIAL FOR THE The present invention relates to the development of a low cost polymeric material formed by an a-cellulose coating and a synthetic copolymer of molecular weight between 500,000 and 1,000,000 g / mol, obtained by diffusion copolymerization of a monomer mixture. to an aqueous solution of surfactant. The resulting material, which is a fine, porous powder, has the capacity to absorb high amounts of crude oil in aqueous spills in a very short period of time and remains floating on the water surface at the end of the absorption.

BACKGROUND OF THE INVENTION Due to the oil spills that have occurred in the last decade such as the one that occurred in April 2010 in the Gulf of Mexico in which a platform operated by the British Petroleum company exploded causing an oil spill for 87 days, they have caused a global concern about the urgent need to control accidental and caused oil spills during transportation and storage. The adverse impact on ecosystems and the long-term effects of environmental pollution require the development of materials for the remediation and cleaning of these areas.

For the remediation of areas contaminated with oil, a great variety of materials such as dispersants, absorbers, solidifiers and foamers have been used. The dispersants simply disperse the oil to lighten it and separate it from the water by absorption. Absorbents collect oil and separate it from water by absorption. Solidifiers are dry granules, hydrophobic polymers that react with oil to form a cohesive, solidified mass that floats on water. Foamers physically encapsulate the oil for collection and are used to recover oil from the surface of the water.

The absorbent materials are attractive for some applications due to the possibility of collection and complete removal of the oil from the contaminated site. The addition of sorbents in oil contaminated areas generates a change from liquid to semi-solid phase and once this change has been made, the removal of the oil by removing the absorbent is much easier. In addition, these materials can, in some cases, be recycled. Some properties of a good absorbent material include high hydrophobicity and oleophilicity, high capacity and high rate of absorption, retention, simple separation of oil from the absorbent, reusability and biodegradation of the absorbent.

Various absorbents have been developed which exhibit at least some of said properties, for example modified clays, silicas, exfoliated graphite, hydrocarbon and plastic polymers, cellulose-based materials and elastomers. All these materials have porosity and ability to absorb oil in the presence of water. It has been proposed that petroleum-absorbing materials can be grouped into three main classes: inorganic mineral products, synthetic organic products and organic vegetable products. Mineral products include materials such as zeolites, silica, perlite, graphite, vermiculites, absorbent clays and diatomites. Synthetic organic products include polymeric materials such as polypropylene and polyurethane foams, which are the commercial absorbents most commonly used to clean oil spills due to their oleophilic and hydrophobic characteristics. An important disadvantage of these materials is that they degrade very slowly compared to mineral or vegetable products. Some examples of organic vegetable products (also known as absorbent natural) that have been studied include straw, corn cob, cotton fiber and cellulose fibers. However, such organic plant products have shown poor flotation characteristics, relatively low oil or hydrocarbon absorption capacity and low hydrophobicity.

Some patents on materials and procedures for absorbing oil in aqueous spills have also been registered. For example, US Pat. No. 3607741 (1971) deals with a cellulose-based material (from newspapers or wood shavings) and adds an amount of air inside the cellulose structures in order to float and also they give it a treatment with certain water repellents (silicone, paraffin, stearate and emulsifier). On the other hand, the patent US 5609667 (1997) talks about the treatment of cotton seeds with sulfuric acid with the aim of obtaining a solid material rich in cellulose (95-97%), which is subsequently treated with ammonium sulfate, the result is a powder. In this patent they mention all the advantages of the material such as the great affinity to hydrocarbons and the ease of supporting microbial growth for its biodegradation, however, none of the patents mentioned talks about any method of synthesis of some copolymer to be used in the absorption of the Petroleum.

The patent US 4832852 (1989) deals with the manufacture of a fibrous material where at least the first fibers (of the surface) are not woven, said material serves for the recovery of oil in aqueous spills or other surfaces. This material uses cotton fibers of waste with various lengths, this material recovers the oil through a compression process. The patent number US 4006079 (1977) speaks of a method to remove oil, oil, etc., which consists of woven cloths containing fiberglass filaments which are put in the contaminated waters to absorb the liquid and subsequently said fiber is Pressed mechanically to extract the oil.

Some patents have also been registered on polymeric materials for the absorption of petroleum, such is the case of the patent US 4340486 (1982) which deals with the manufacture of a device that consists of a network of an oleophilic-hydrophobic material that is molded and then a handle is adapted for handling. The material is made from polyethylene and polypropylene. This material has the advantage of retaining the oil or hydrocarbon by absorption within the internal spaces of the network, allowing a rapid absorption that is 2 to 3 times greater than the references of the US 3748682 and US 3748682 patents and the oil can be Removed in just 60 seconds after its absorption. However, these patents also do not talk about any synthesis method of a synthetic copolymer to be used in the absorption of oil.

The invention CN101550261 A (China, 2009) discusses a composite containing a cellulose filler (waste) and a method for its preparation. Which consists of an acrylic polymer as a base material in which the cellulose is dispersed in the form of "islands" or agglomerates and which is capable of absorbing high amounts of oil. The preparation includes obtaining the acrylic polymer and mixing it with cellulose. The invention CN101565487A (China, 2009) deals with a method for preparing a petroleum absorbent material from cellulose grafted with polymerized alkyl acrylate monomers, that is, the synthetic polymer forms chemical bonds with the cellulose macromolecules, which is possible because to the formation of radicals in the cellulose macromolecule that bind with the synthetic polymer. The method consists of pulverizing the cellulose from plants, placing it in aqueous nitric acid solution containing cerium ionic initiator, stirring, removing the excess of the pre-treatment fluid, washing the residual cerium with distilled water until pH 7 and subsequent filtration vacuum by placing the filtrate in an aqueous solution of nitric acid and adding copper lamellae to inhibit the formation of homopolymer. The monomer and a crosslinker are then added to the reactor under a nitrogen atmosphere with stirring at a constant temperature. The product is precipitated and filtered, and then washed with ethanol and dried. The invention CN101565488 A (China, 2009) deals with a method of preparing a cellulose-based material for the absorption of oil, which consists of the activation of cellulose, addition of polyvinyl alcohol in aqueous solution, stirring and heating in the presence of nitrogen, addition of the initiating agent, reaction of monomer and crosslinker, heating under stirring at constant temperature. The product is precipitated, filtered, washed with hot water and dried. The invention CN101565604 deals with a method of preparing a petroleum absorbing material synthesizing di-butyl sebacate grafted to cellulose. This method consists of pulverizing plant cellulose, adding an aqueous solution of sodium hydroxide, stirring with reflux, filtering, washing with neutral water, compression for its placement in di-butyl sebacate synthesized previously from decadicioic acid, n-butanol and catalyst by heating with reflux and adding water and an initiator, stirring with heating in the presence of nitrogen and reacting at constant temperature. The product is precipitated, filtered, washed with water and ethanol to proceed to dry. As you can see, these last four mentioned patents talk about polymer synthesis processes but these polymers are chemically grafted to the cellulose macromolecules, that is, as mentioned previously, the synthetic polymer forms chemical bonds with the cellulose macromolecules, which is possible due to the formation of radicals in the cellulose macromolecules that are bound to the synthetic polymer, but at no time do they speak about a cellulose coating with said polymers, that is, a physical mixture of cellulose with synthetic copolymers where the Cellulose is in proportions between 50% to 90%. In addition, the synthesis processes mentioned are in aqueous solution but do not refer to a diffusion polymerization of the monomers towards an aqueous solution of surfactants (surface tension modifiers). On the other hand, they refer to the use of cerium initiators, but do not mention the use of initiators such as persulfates.

BRIEF DESCRIPTION OF THE INVENTION The invention whose protection is requested, is capable of absorbing crude oil present in aqueous spills, where two phases are formed: a lower aqueous and a higher organic constituted mainly by petroleum hydrocarbons, reducing the time and cost of the oil absorption process raw. In addition to being a highly hydrophobic polymeric material, that is, it has affinity only for non-polar chemical substances such as hydrocarbons and completely repels polar substances such as water. Said hydrophobic property is imparted by the synthetic copolymers of styrene and butyl acrylate which constitute the polymeric material. The material is constituted mainly by 50% to 90% of α-cellulose and 50% to 10% of copolymer of styrene and butyl acrylate. In addition, it is applied in the form of powder and when the absorption is carried out, it agglutinates and remains floating on the surface, thus facilitating its recovery. Another advantage of the polymeric material is that it is constituted by at least 50% to 90% of a-cellulose, which is completely biodegradable, which makes it environmentally friendly.

DETAILED REALIZATION OF THE INVENTION Manufacturing of the petroleum absorbent material: obtaining the absorbent material consists of two stages, one which is the obtaining of the copolymer and another which is the coating of α-cellulose with the copolymer.

I. Obtaining the synthetic copolymer. The copolymer is obtained by means of a diffusion process. A quantity of between 60 and 90% of water is mixed, between 1 and 15% of surfactant (which can be sodium dodecyl sulphate whose chemical formula is CH3 (CH2) i, OS03Na or sodium dioctyl sulfosuccinate whose chemical formula is C2oH37Na07S), between 0.2 and 0.5% of an initiator that can be potassium persulfate or ammonium persulfate with an agitation of between 100 and 300 revolutions per minute (so as not to form a vortex) until a homogeneous and transparent solution is obtained. Subsequently add between 40 and 10% of a mixture of monomers of styrene and butyl acrylate in a ratio of between 75% styrene / 25% butyl acrylate to 95% styrene / 5% butyl acrylate, so as to form an upper phase of the monomer mixture and a lower phase of aqueous surfactant solution and initiator. The mixture is heated between 40 and 80 ° C to start the polymerization and is kept at this temperature for 6 hours. As the copolymerization is carried out, the monomers in the upper phase diffuse continuously into the aqueous phase where the copolymerization occurs. The resulting mixture containing the copolymer consisting of repeating units of styrene and butyl acrylate (See Figure 1) is subjected to drying at a temperature between 40 and 70 ° C for 48 hours until a material with the appearance of a colored powder is obtained. White.

II. Mix of synthetic copolymer and α-cellulose. The copolymer obtained in step I is mixed with α-cellulose in a ratio of copolymer to α-cellulose of between 50%: 50% and 90%: 10% (mixture A). The mixture A is homogenized and then a solvent is added which may be tetrahydrofuran (C4H80) or toluene (C7H8) in a proportion of mixture A to solvent of between 10%: 60% and 50%: 50%. The resulting mixture is homogenized and dried in a forced convection drying oven at a temperature between 30 ° C and 70 ° C for a period of between 24 and 48 hours.

PREFERRED EMBODIMENT OF THE INVENTION I. Obtaining the synthetic copolymer. Mix an amount of between 80% water, 2.4% sodium dodecyl sulfate, 0.48% potassium persulfate with an agitation of between 150 revolutions per minute (so that a vortex is not formed) until a homogeneous solution is obtained and transparent. Subsequently, between 16.18% of a mixture of styrene and butyl acrylate monomers is added in a ratio of 80% styrene / 20% butyl acrylate, so that when an upper phase of the monomer mixture is formed and a lower phase is added of aqueous solution of surfactant and initiator. The mixture is heated to 60 ° C to start the copolymerization and is maintained at this temperature for 6 hours. As the copolymerization is carried out, the monomers in the upper phase diffuse continuously into the aqueous phase where the copolymerization occurs. The resulting mixture containing the copolymer is subjected to drying at a temperature of 60 ° C for 48 hours.

II. Mix of synthetic copolymer and α-cellulose. The copolymer obtained in the previous step is mixed with α-cellulose in a ratio of copolymer to α-cellulose of 30%: 70% (mixture A). The mixture A is homogenized and then tetrahydrofuran is added in a proportion of mixture A to tetrahydrofuran of 40%: 60%. The resulting mixture is homogenized and dried in a forced convection drying oven at a temperature of between 60 ° C for a period of 48 hours.

Claims (3)

BRIEF DESCRIPTION OF IAS FIGURAS Figure 1 . Copolymerization reaction between the monomers of styrene and butyl acrylate showing the repeating unit of the resulting copolymer. Figure 2. Schematic representation of the application form of the polymeric material in the absorption of oil in aqueous spills. CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. Method for obtaining a polymeric material consisting of a copolymerization by a diffusion process and characterized by mixing an amount of between 60 and 90% of water, between 1% and 15% of surfactant (which can sodium dodecyl sulfate whose chemical formula is CH3 (CH2) iiOS03Na or sodium dioctyl sulfosuccinate whose chemical formula is C2oH37Na07S), between 0.2 and 0.5% of an initiator that can be potassium persulfate or ammonium persulfate with an agitation of between 100 and 300 revolutions per minute (so that a vortex is not formed) until obtaining a homogenous and transparent solution; Subsequently, between 40 and 10% of a mixture of styrene and butyl acrylate monomers is added in a ratio of between 75% styrene / 25% butyl acrylate at 95% styrene / 5% butyl acrylate, so as to form a upper phase of the monomer mixture and a lower phase of aqueous solution of surfactant and initiator; the mixture is heated between 40 and 80 ° C to start the polymerization and is kept at this temperature for 6 hours; to As the copolymerization is carried out, the monomers in the upper phase diffuse continuously into the aqueous phase where the copolymerization takes place; the resulting mixture containing the copolymer consisting of repeating units of styrene and butyl acrylate (See Figure 1) is subjected to a drying at a temperature of between 40 and 70 ° C for 48 hours until a material with the appearance of a colored powder is obtained White; the obtained copolymer is mixed with α-cellulose in an a-cellulose copolymer ratio of between 50%: 50% and 90%: 10% (mixture A); Mixture A is homogenized and then a solvent that can be tetrahydrofuran (C4H80) or toluene (C7H8) is added in a mixture ratio of A to solvent of between 10%: 60% and 50%: 50%; The resulting mixture is homogenized and dried in a forced convection drying oven at a temperature between 30 ° C and 70 ° C for a period of between 24 and 48 hours.

2. Polymeric material obtained according to claim 1, characterized in that it can be used for the absorption of oil and some of its derivatives when put in physical contact; and because it is also hydrophobic and porous.

3. Polymeric material obtained according to claim 1, characterized in that it can absorb oil and some of its derivatives in aqueous spills when put in physical contact, as explained in Figure 2, so that it acts as a binder and that At the end of the absorption process, the saturated hydrocarbon material remains floating on the water surface.