PL233206B1 - Hydrophobic filter, selectively absorbing oils and organic compounds, intended for cleaning of waters and method for production of the filter - Google Patents

Description

Description of the invention

The subject of the invention is a hydrophobic filter that selectively absorbs oils and organic compounds, intended for water purification based on wood products coated with carbon nanomaterials, and the method of its production. The filters can be used mainly in ocean oil spills, absorbing oils and organic compounds from the water surface.

The use of natural fiber filters is one of the possible methods of removing ocean oil spills. Fibers such as kapok, cotton, milkweed and clubs were the most frequently described [H. Choi et al., Environ. Sci. Technol. 1992,26 (4), 772-776; Cao et al., J. Nat. Fibers 2017, 0 (0), 1-9].

Moreover, it has been observed that pure cotton and kapok fiber exhibit hydrophobic properties, present due to the naturally present thin layer of wax while absorbing oils [Singh et al., Ind. Eng. Chem. Res. 2014, 53 (30), 11954-11961].

Also natural and synthetic polymers in the form of powder, granules or fibers, such as wood, cotton, grass, straw, cellulose with additives of metal / ammonium compounds show selective oil absorption - US Patent 4,780,518.

Not only natural and polymeric materials are used as selective filters. Carbon nanomaterials such as graphene, graphene oxide, reduced graphene oxide, graphene nanoflakes and carbon nanotubes have been formed into spongy structures or aerogels with very strong absorbent properties (for oils and organic solvents) and superhydrophobicity [Gupta et al., J. Mater. Chem. A 2016, 4 (5), 1550-1565].

However, despite very good selective absorption properties, carbon nanomaterials in the form of sponges and aerogels are not widely used so far due to the high price. Consequently, the natural fibers have been coated to obtain selective absorption.

Cotton filters were coated with, among others, silicon oxide nanoparticles [Liu et al., Carbohydr. Polym. 2014, 103 (1), 480-487.], Hydrophobizing polymers [Li et al., Phys. Chem. Chem. Phys. 2015, 17 (9), 6451-6457; Lee et al. Lee, J. H .; Kim, D. H .; Kim, Y. D. J. Ind. Eng. Chem. 2016, 35, 140-145.] And carbon nanomaterials [Ge et al., Compos. Sci. Technol. 2014,102,100-105; Hoai et al., Mater. Sci. Eng. B 2016,216,1-6; Cortese et al., J. Mater. Chem. A 2014, 2 (19), 6781.].

In addition, carbon nanotubes, including those applied to natural fibers, have also been used to purify liquids as disclosed in EP1885647 and US2005263456.

Natural fibers covered with carbon nanotubes can also serve as a liquid separator. Such a state of affairs is known from patents US2010116751 and US 9126128.

Other carbon nanomaterials, including graphene, graphite and carbon fibers, have also been described as coatings for making oil-water separators - EP 2929925 and WO 2015141902. In addition, oils can be removed or filtered from the water surface using a boom holding a filter consisting of from carbon nanotubes deposited on fibers - description US2015275452.

Carbon nanotubes embedded in fibers such as polyethylene, cotton and other natural fibers can be used to remove contaminants from the surface of solids. The contaminants described include microbial contaminants, pollen, liquids, and others - US2009196909.

The solution according to the invention focuses on the use of products derived from the wood industry, such as wood flour and others, coated with carbon nanomaterials to produce a selective oil absorber. The use of pure wood materials as a sorption material is known, however, due to their hydrophilic nature and strong water absorption, their use is limited. Moreover, their sorption properties and the possibility of reusability are slightly worse than in the case of other fibers such as kapok and cotton. However, their low price is a very significant advantage compared to all other sorption materials. Covering wood products with carbon nanomaterials causes hydrophobization and enables the invention to be used as a selective absorber. In addition, the use of mesh material around the used wood material prevents uncontrolled scattering or dissolving of the material. It is worth mentioning that the price of carbon nanomaterials has dropped several hundred times over the last 20 years and only now can it be comparable to the price of the base material of the filter. In addition, the production of carbon nanomaterials has been developed in the last few years, enabling their mass production.

PL 233 206 B1

The essence of the invention is a hydrophobic filter that selectively absorbs oils and organic compounds intended for water purification, containing wood products, in which wood products in the form of wood flour, wood shavings, wood pulp, wood shavings, wood fibers, wood wool, wood dust, sawdust or other waste wood, placed (closed) loosely in a mesh material made of natural or artificial fibers covered with carbon nanomaterial. The mesh material of natural or artificial fibers is sized in such a way that liquids can pass through freely, while the wood products used should be trapped in it.

In the optimal variant, the natural fiber mesh material is made of hydrophobized fibers woven from cotton, linen, wool, bamboo, coconut fiber or bamboo fiber, and in the case of synthetic fiber: polypropylene, polyethylene, polyester, polyurethane, polycarbonate, polyamide, polyolefin, glass fiber or carbon fiber.

Preferably, the carbon nanomaterials are single-walled and multi-walled carbon nanotubes, helical carbon nanotubes, other carbon nanofibers, graphene nanoflakes, graphite nanoflakes, reduced graphene oxide or carbon black.

It is advantageous when the filter paper produced is additionally modified with a hydrophobic polymer.

The essence of the invention is also a method of producing a hydrophobic filter intended for water purification, in which, in the first place, loose wood products in the form of wood flour, wood shavings, wood pulp, wood clippings, wood fibers, wood wool, wood dust, sawdust or other wood waste, is placed loosely in a mesh material made of natural or artificial fibers, then the whole is covered with a suspension of carbon nanomaterial in an organic compound such as: chloroform, dichloromethane, dichloroethane, acetone, benzene, isopropanol, ethanol, methanol, N-methylpyrrolidone, toluene and the like , or mixtures of these compounds or a mixture thereof with water, by means of immersion or spraying methods, and then the organic compound is evaporated. It is also allowed to replace the suspension of carbon nanomaterial in an organic compound or mixtures of these compounds or their mixture with water - suspension of carbon nanomaterial in a solution of water with a surfactant, such as sodium dodecyl sulfate, polysorbate 80 and the like, or a stabilizing polymer such as cellulose, starch, polyalcohol vinyl and the like, adequately removing the surfactant or stabilizing polymer by first evaporating the water.

It is preferred that the suspension of carbon nanomaterial in an organic compound, or mixtures of these compounds or their mixture with water, is previously stabilized by adding a stabilizing polymer such as cellulose acetate, methyl cellulose, polyethylene, polyethylene oxide and the like.

It is also advantageous when as a natural fiber mesh material fibers woven from cotton, linen, wool, bamboo, coir or bamboo fiber are used, and from synthetic fibers: polypropylene, polyethylene, polyester, polyurethane, polycarbonate, polyamide, polyolefin, glass fiber mesh. or carbon fiber.

In a variant of the method according to the invention, prior to placing the wood products in the netting material, the natural netting material is covered with carbon nanomaterial for the purpose of its hydrophobization.

It is preferred that single-walled and multi-wall carbon nanotubes, helical carbon nanotubes, other carbon nanofibers, graphene nanoflakes, graphite nanoflakes, reduced graphene oxide or carbon black are used as carbon nanomaterials.

Optionally, carbon nanomaterials can be modified with a hydrophobic polymer.

In an embodiment variant, after production, the filters are additionally covered with a hydrophobic polymer.

The use of nanomaterials in the solutions according to the invention is aimed at hydrophobizing the surface of wood products, so that they do not absorb water. At the same time, their ability to absorb other liquids is not limited. The use of wood-based products, such as, for example, wood flour coated with nanomaterials, such as carbon nanotubes and graphene nanoflakes, will allow for the creation of a cheap composite for removing oil from the water surface. The use of the suggested filters will absorb only the spilled crude oil, without absorbing any water. Low cost of filter production is necessary for ocean applications around the mining platform.

The filter according to the invention is used in the field of water purification and environmental protection for the purposes of oil-water separation, selective absorption of oil from water, absorption of oily substances and crude oil from the water surface, as a protective barrier against ocean spills,

They will also allow the absorption of water-insoluble organic compounds from the surface or volume of water.

The invention, in an embodiment, is shown in the drawing, in which Fig. 1 shows a schematic diagram of the bag and the cycle of its production. In Fig. 1, under the letter A), there is shown a wood material 1 (chipped wood) and a mesh material 2 (a hydrophobic natural fiber, in a variant also a naturally water-repellent polymer or carbon fiber). B) shows the application of the material 1 to the mesh material 2 - the fiber mesh, and then it is wrapped with it. C) shows wood material 1 wrapped with mesh material - fiber 2.

Then, the carbon nanomaterial is applied by immersing the carbon nanomaterial in a suspension in an organic compound, for example chloroform, and drying the sample. It is advantageous to repeat the dipping procedure several times in order to obtain the most hydrophobic layer possible.

It is obvious to those skilled in the art that the procedure can also be performed in a different order, that is, apply the appropriate amount of nanomaterial to loose wood flour and then place it in the mesh.

In an embodiment, the filter was made using graphene as carbon nanomaterial, cotton gauze as mesh material 2 and wood flour as wood material 1.

In method I of the embodiment, 1 g of graphene nanoflakes was thrown into 1000 ml of chloroform. The suspension was homogenized using an ultrasonic homogenizer. The power supplied by the homogenizer was 100 W. The process time was 20 min. Then, 20 g of the defibrated wood was placed in the vessel, and then poured over 200 ml of the prepared solution. The soaked wood flour was dried at 70 ° C for 2 hours until the chloroform was completely evaporated. Soaking and drying was repeated 5 times. The wood flour coated with graphene nanoflakes was then wrapped with a polyamide mesh with a mesh size of 1.2 mm.

In method II of the embodiment, 1 g of graphene nanoflakes was thrown into 1000 ml of dichloromethane. The suspension was homogenized using an ultrasonic homogenizer. The power supplied by the homogenizer was 100 W. The process time was 20 min. Then 20 g of wood flour was wrapped with a cotton mesh with a mesh size of 2 mm. The wood flour, wrapped in a cotton net, was placed in the vessel and then poured with 200 ml of the prepared solution. The soaked wood flour was dried at 70 ° C for 2 hours until the chloroform was completely evaporated. The soaking and drying were repeated 5 times. Then, 2 ml of the hydrophobizing polymer, poly (dimethylsiloxane), was diluted with 200 ml of chloroform. The resulting cotton-netted wood flour was then dipped in a dilute solution of poly (dimethylsiloxane). The soaked filter was dried at 70 ° C for 2 hours until the chloroform was completely evaporated.

In an embodiment variant, the filter paper produced may be additionally modified with a hydrophobic polymer. Optionally, the carbon nanomaterials themselves can also be modified with a hydrophobic polymer.

The effectiveness of the solution is confirmed by the tests performed. The weighed sample was soaked in water and an organic solvent (chloroform), reweighed and dried after each immersion. The selectivity of the absorption and the absorbency were calculated. The selectivity of the absorption, measured as the quotient of the weight of the absorbed organic compound to the sum of the weight of the absorbed water and organic compound, increased from 53% for pure wood flour to 97.8% for graphene-coated wood flour. On the other hand, the absorbency, measured as the weight of water absorbed per 1 g of filter, dropped from 15.4 g / g to 0.4 g / g.

Claims (11)

Patent claims 1. A hydrophobic filter, selectively absorbing oils and organic compounds, intended for water purification, containing wood products, characterized by the fact that it is made of wood products (1) in the form of wood flour, wood shavings, wood pulp, wood scraps, wood fiber, wood wool, wood dust , sawdust or other wood waste coated with carbon nanomaterial, preferably a modified hydrophobic polymer, which are loosely placed in the mesh material (2) made of natural or artificial fibers. PL 233 206 B1 2. A filter according to claim 1, characterized in that the natural fiber mesh material (2) is made of hydrophobized fibers woven from cotton, linen, wool, bamboo, coconut fiber or bamboo fiber, and from synthetic fiber: polypropylene, polyethylene, polyester, polyurethane, polycarbonate, polyamide mesh, polyolefin, glass fiber or carbon fiber. 3. A filter according to claim 5. The method of claim 1 or 2, wherein the carbon nanomaterial is single-walled and multi-walled carbon nanotubes, helical carbon nanotubes, other carbon nanofibers, graphene nanoflakes, graphite nanoflakes, reduced graphene oxide or carbon black. 4. A filter according to claim A method according to any of the claims 1 to 3, characterized in that it is additionally covered with a hydrophobic polymer. 5. The method of producing a hydrophobic filter selectively absorbing oils and organic compounds intended for water purification, characterized in that loose wood products (1) in the form of wood flour, wood shavings, wood pulp, wood clippings, wood fiber, wood dust, sawdust or other waste wood, are placed loosely in the mesh material (2) made of natural or artificial fibers, and then the whole is covered with a suspension of carbon nanomaterial in an organic compound, such as: chloroform, dichloromethane, dichloroethane, acetone, benzene, isopropanol, ethanol, methanol, N- Methylpyrrolidone, toluene and the like, or mixtures of these compounds or a mixture thereof with water, or a suspension of carbon nanomaterial in a solution of water with a surfactant such as sodium dodecyl sulfate, polysorbate 80 and the like, or a stabilizing polymer such as cellulose, starch, polyvinyl alcohol and the like, by immersion or spray methods followed by evaporation of the organ compound or the surfactant or stabilizing polymer is removed by previously evaporating the water. 6. A method for producing a hydrophobic filter according to claim 1 The process of claim 5, characterized in that the suspension of carbon nanomaterial in an organic compound or mixtures of these compounds or their mixture with water is previously stabilized by adding a stabilizing polymer such as cellulose acetate, methyl cellulose, polyethylene, polyethylene oxide and the like. 7. A method for producing a hydrophobic filter according to claim 1, 5 or 6, characterized in that hydrophobized fibers woven from cotton, linen, wool, bamboo, coconut fiber or bamboo fiber are used as the mesh material (2), and the synthetic fibers are: polypropylene, polyethylene, polyester, polyurethane mesh, polycarbonate, polyamide, polyolefin, glass fiber or carbon fiber. 8. A method for producing a hydrophobic filter according to claim 1, 5. The method of claim 5, 6 or 7, characterized in that prior to placing the wood products (1) in the mesh material (2), the natural mesh material (2) is covered with carbon nanomaterial. 9. A method for producing a hydrophobic filter according to claim 1, The method of 5, 6, 7 or 8, characterized in that single-wall and multi-wall carbon nanotubes, helical carbon nanotubes, other carbon nanofibers, graphene nanoflakes, graphite nanoflakes, reduced graphene oxide or carbon black are used as carbon nanomaterials. 10. A method for producing a hydrophobic filter according to any one of the preceding claims. 5. The method according to 5 to 9, characterized in that the carbon nanomaterials can be modified with a hydrophobic polymer. 11. A method for producing a hydrophobic filter according to any one of the preceding claims. The method according to 5-10, characterized in that the filters, after their production, are additionally covered with a hydrophobic polymer.