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    • 专利摘要:
    Nanostructured electrolyte useful for desalination by direct osmosis. Procedure for obtaining the electrolyte and its uses. The nanostructured electrolyte based on magnetic iron oxide magnetic nanoparticles is easily separable with a magnet and comprises a ligand coating the surface strongly bound to the nanoparticle by one end and in the other it contains a functional group that provides high osmotic pressure for use in processes of potabilization of sea or continental water through direct osmosis. The electrolyte is also reusable. The invention also relates to the process for manufacturing the electrolyte and its use, for example, in desalination processes. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2554578A1
    申请号:ES201430721
    申请日:2014-05-19
    公开日:2015-12-21
    发明作者:Sabino Veintemillas Verdaguer；Maria Del Puerto MORALES HERRERO；Carlos SERNA PEREDA；Cristina MARSANS ASTORECA；Verónica LÓPEZ HERRERO
    申请人:Jayim Mayin Slu；Jayim Mayin S L U；Consejo Superior de Investigaciones Cientificas CSIC；
    IPC主号:
    专利说明:

    Field of the Invention
    The invention falls within the technical sector of filter materials for the treatment of fluids, more specifically those used in the desalination processes of
    10 inland waters as well as from the sea and in the field of nanotechnology development. In particular, the invention relates to a new nanostructured electrolyte based on magnetic iron oxide magnetic nanoparticles, which allows it to be easily separated with a magnet, and therefore reusable. The electrolyte comprises a ligand covering the surface tightly bound to the nanoparticle at one end and at the other
    15 contains a functional group that provides high osmotic pressure for use in processes of purification of sea or continental water by direct osmosis.
    Other objects of the invention are a process for obtaining the electrolyte and its use, for example, in desalination processes.
    State of the art
    Osmosis is a physical phenomenon in which water diffuses naturally through a semipermeable membrane from a zone of low concentration to a zone more
    25 electrolyte concentrate (organic salts or impurities) until equilibrium is reached. Electrolytes are any substance that generates free ions in solution, and that is dissolved in a given solution, in a smaller proportion than the solvent (salts or unwanted elements). The semi-permeable membrane is a barrier that separates two solutions and allows the passage of water through it and rejects electrolytes.
    30 Water desalination processes are based on the use of semipermeable membranes that mostly pass water molecules and retain dissolved salts or other contaminating molecules. The natural process of flow of water molecules through the membrane is from lower to higher concentration of salts,
    35 so it is necessary to increase the pressure above the osmotic pressure (pressure that must be applied to a solution to stop the natural flow of solvent through a

    semipermeable membrane) by pumping in the area with the highest concentration of electrolytes towards the one with the lowest concentration of salts so that the water flow is in the opposite direction to the natural one (reverse osmosis). In the current desalination plants, this represents 80% of the energy required, generating costs around 2 kWh / m3, for the desalination stage at best.
    There is a great interest in improving the energy efficiency of water desalination processes and recently, great efforts are being made in developing alternative processes, which make it possible to reduce the energy consumption of the osmosis process (not including pre-treatment or post-treatment processes) by reducing the Emissions of greenhouse gases. One of the possibilities is based on using the phenomenon of direct osmosis, in which unlike inverse osmosis, the pressure difference is generated by adding an electrolyte in the purified water (sol uta extractor), which increases the osmotic pressure above the value of the incoming salt water. With this strategy, water naturally passes from the contaminated source to the sun compartment or extractor.
    The extractor sol is designed so that at a later stage it can be easily removed / recycled leaving pure water (TY Cath, et al, J Membrane Science, 281, (2006J-70) The techniques for recovering the extracting solute vary depending on the properties of the same.The most used are heating / evaporation, precipitation, pH adjustment, membrane processes (ultrafiltration) or use of magnetic fields.In these conditions the osmosis process can generate drinking water from seawater to a cost only of 0.25 kWh / m3 (cost of the osmosis stage), theoretical limit presented in A. Subramani, et al, Water Research, 45, (2011), 1907. The cost of the separation stage of the extracting solute is variable depending on its nature and constitutes an important part of the energy cost of the process.
    The extractor or electrolyte sol can be formed by magnetic nanoparticles coated by ligands and are used in an aqueous solution in which the magnetic nanoparticles coated with the electrolyte are dispersed. The salt water solution and the magnetic nanoparticle solution are contacted through the membrane. Water flows through the membrane of the most diluted side (salt water) to the most concentrated side (solution of magnetic nanoparticles).
    The use of nanostructured materials as solute extractor allows to concentrate the molecular groups that generate osmotic pressure in a discrete electrolyte of zero toxicity,

    Easy recovery and low recovery cost. In this case, the electrolyte is a coated organic or inorganic nanoparticle that has sufficient charges to generate osmotic pressure. The use of these electrolytes allows to increase the efficiency and capacity of the desalination system in terms of the recovery of drinking water and the recycling of the material for its new use. Recovery can be carried out by changing pH, ultrafiltration or magnetic fields.
    Within nano structured materials, magnetic nanoparticles provide the ability to use immobilizing magnetic fields for separation. Unlike the separation processes of the extracting solute based on the heating of the solution or ultrafiltration, the magnetic field acts exclusively on the electrolyte that is intended to separate and not on the whole of the solution (heating) or on the water (ultrafiltration ) and is, in principle, an alternative of lower energy cost. Recovery can be carried out through the use of external magnetic fields and their recycling is possible thanks to the nanometric character of the nanoparticles. The magnetic behavior of these electrolytes is superparamagnetic, that is to say they have zero remanence to zero field, so they do not remember that they have been magnetized as soon as the magnetic field is eliminated, thus minimizing their aggregation and enabling their recirculation.
    W010043914 discloses a process of water purification by direct osmosis, where the stream of water to be treated and an extracting solution with magnetic nanoparticles are contacted through a semipermeable membrane, so that pure water passes from the stream to treat the current containing the solute extractor, then separating said solute magnetically.
    Document W011099941 also discloses the use of an electrolyte based on hydrophilic magnetic nanoparticles in direct osmosis procedures. The electrolyte comprises a magnetic nanoparticle that can be of Fe20 3 and a hydrophilic polymer covalently bonded to the core.
    For direct osmosis, the synthesis of nanoparticles with a small size and therefore with a large specific surface is necessary, a property that relates the total surface area and the mass of the solid (m2 / g) where the smaller the particle size, the larger The number of nanoparticles is in a gram, so the total surface area is greater so that the surface modification allows a large number of functional groups to be incorporated. Those

    Functional groups are those that dissociate in aqueous solution to give high osmotic pressure. However, smaller magnetic nanoparticles are difficult to capture with low energy costs using a magnetic separator due to their low magnetic moment per particle.
    The ideal sun extract should have both high specific surface area and high magnetic moment per particle. The current techniques used only allow nanoparticles with a size of up to 10 nm to be obtained (by coprecipitation techniques), which limits their specific volume. Larger nanoparticles synthesized at high temperature in organic solvents have shown a smaller magnetic moment per particle than would be expected due to structural defects which would make their separation difficult (A Quarta, al, Chemislry 01 Malerials, 23, (18), (2011), 4170). It would therefore be advantageous to have a magnetic electrolyte that had a higher volume and high magnetic moment so that it could be easily separated by means of magnetic fields.
    So far, most electrolyte desalination processes based on magnetic nanoparticles have been tested on a laboratory scale, using maximum initial solutions of 50 ml (O. Ge el al, Industrial Engineering. Chemical Research 50, (2011), 382) . An important limitation of the direct osmosis method is that it is necessary to use suspension of highly concentrated nanoparticles to obtain sufficient osmotic pressure (of the order of 400 gIL), this entails the need to synthesize relatively large quantities of magnetic nanoparticles. Current methods of synthesis in organic media that allow nanoparticles to be synthesized with adequate magnetization have the disadvantage of the high price of organic solvents that make the final product more expensive and the difficulty of scaling the process. Normally these syntheses produce milligrams of nanoparticles as seen in W011099941. For real-scale application it is necessary to have procedures that increase performance and remain cheap.
    Explanation of the invention.
    The invention provides in a first aspect a nanostructured electrolyte useful for direct osmosis desalination that is composed of magnetic iron oxide nanoparticles whose core is magnetite, coated with solid state polyacids, wherein:

    - the polyacid constitutes a weight percentage of between 5 and 10% of the electrolyte,
    - the nanoparticles have a size between 20 and 100 nm and a specific surface area between 70 and 23 m2 / g, and - the electrolyte has a magnetization greater than 3.1 E-14 emu / nanoparticle; and the zeta potential of the electrolyte in aqueous suspension at pH = 7, is less than -20 mV and greater than -30 mV.
    The polyacid may be composed of the union of monomers containing acidic groups including at least one of the following: polyacrylic acid and its derivatives, understood as derivatives other polymers where polyacrylic acid blocks are included together with blocks of other polymers or polymethacrylic acid . Preferably polyacrylic acid of a molecular weight less than 3000 Da.
    The average electrolyte size deviation is less than 20%.
    The invention provides in a second aspect a method for obtaining the
    electrolyte of the first aspect, said process comprising the following steps: a) preparing magnetic nanoparticles, whose core is magnetite, by oxidative precipitation of iron salts (11) in basic medium in the absence of oxygen; b) thermally treat the nanoparticles, in the presence of polyacids and in the presence of a non-aqueous solvent of boiling point greater than 200 ° C in a nitrogen atmosphere, and simultaneously distill the residual water at a temperature between 200-300 ° C; And c) separate the electrolyte.
    In an exemplary embodiment, step a) comprises the following steps: a1) prepare under nitrogen a solution A containing sodium nitrate and sodium hydroxide in degassed water, a2) prepare a solution B with ferrous sulfate heptahydrate in a solution of sulfuric acid, a3) add solution B on A under stirring at more than 300 rpm, a4) transfer a suspension of green iron oxohydroxide, e, formed from the
    mixing the solution B over the A in the previous step a3, to a thermostatic vessel previously heated to 90 ° C where the suspension is left at said temperature and without stirring for more than 20 hours,
    a5) extract the cold suspension from the nitrogen atmosphere,a6) separate the nanoparticles from the suspension, anda7) Dry the nanoparticles to remove traces of moisture.
    5 According to an exemplary embodiment in step a7), the nanoparticles are dried at 200 ° C for 1 to 4 hours to remove traces of moisture.
    The agitation of step a3) must be vigorous at more than 300 rpm because it influences the size of nanoparticles that are formed. The stirring may be magnetic but preferably mechanical.
    In another exemplary embodiment, the heat treatment of step b) comprises the following steps: b1) preparing a polyacid solution in a non-aqueous solvent of
    15 boiling above 200 oC, b2) adding the nanoparticles prepared in step a) to the poly acid solution prepared, b3) heating the mixture obtained in step b2) using a stirred reactor at a temperature of between 200 -300oC ,
    20 b4) distill the water until the boiling temperature of the solvent is reached, b5) maintain the boiling temperature for at least 30 min, b6) cool to room temperature, and b7) separate the electrolyte from the solution.
    The non-aqueous solvent may be triethylene glycol and, in this case, the temperature of the heat treatment is between 200 and 300 ° C, more preferably at 275 ° C. 1: 25 nanoparticle / polyacrylic acid weight ratios can be used for nanoparticles of 20 nm or less and 1:15 for those larger than 20 nm.
    The electrolyte separation from step c) can be carried out by adding acetone by means of a magnetic separator or by natural decantation.
    The process of the second aspect can be carried out in cavities with means for the introduction and removal of the necessary chemical compounds, in a particular embodiment the reactor is of the reflux stirred tank type.
    In a particular embodiment the electrolytes of the solution are separated by the addition
    of acetone by means of a magnetic separator.
    In previous publications such as W011099941 the procedure for obtaining
    5 coated nanoparticles occur in a single step, so they don't have so much control overthe size and crystallinity of the nanoparticles. In the process of the invention,they obtain the nanoparticles first and then they are coated with the polyacid. In this processThe nanoparticles are synthesized in water and must be removed well to be able to coat withpolyacid forming covalent bond. This has been solved by distilling water to it.
    10 time to cover to allow the reaction temperature to rise.
    The nanoparticles are synthesized in water and subsequently dried at high temperature so that the amount of water they contain is minimal. To coat the nanoparticles, triethylene glycol or other boiling point solvents close to 275 ° C are used. If these
    15 solvents contain a percentage of water, that percentage must be removed to reach the reaction temperature and get the polyacid to covalently bind to the nanoparticles, this can be done simultaneously with distillation.
    The reactor used consists of a system that allows to extract the water that condenses 20 in the reflux system of the reactor.
    The invention provides in a third aspect a use of the electrolyte defined in direct osmosis processes, in particular in desalination systems, both seawater and continental water, including brackish water or low salt content (with a content
    25 of between 50-50000 ppm of salts).
    The invention allows energy savings associated with the substitution of current desalination plants with reverse osmosis by others that use direct osmosis. This consumption savings can also be manifested in the production devices of
    30 water on a reduced scale, which in this way can be fed by photovoltaic cells or other renewable sources of energy. These devices are of great interest in applications where independence from the power grid is desired.

    Brief description of the figures
    The above and other advantages and features will be better understood by reference to the following detailed description in conjunction with the following attached drawings, in which:
    Figure 1. Image of the 50 nm nanoparticles obtained in step a) of the procedure performed in a transmission electron microscope (TEM), 200 kV JEOL-2000 FXI.
    Figure 2. Magnetization curve as a function of the magnetic field applied for the 10 50 nm nanoparticles of this invention in compacted powder measured on a magnetometer, (MLVSM9 MagLab 9 T, Oxford Ins / rumen /).
    Figure 3. Thermogravimetric analysis (at 100 ° C / min in flow of 100 cm 3 / min of air, Seiko Exstar 6300 instrument) indicating the weight loss as a function of the temperature of A) the 15 magnetic nanoparticles of 20 nm obtained in step a of the process and B) the electrolyte of the invention, when they have already gone through step b) of the process.
    Figure 4. Surface charge (Potential Z) of the electrolyte at two concentrations of polyacrylic acid as a function of pH in the presence of N03K at 10-3 M concentration, measured on a ZETASIZER NANO-ZS dispersion analyzer (Malvern Ins / rumen / s Lid., UK).
    Figure 5. TEM image of the electrolyte (200 kV JEOL-2000 FXI and JEOL JEM 2100.), at different magnifications.
    25 Figure 6. Infrared spectrum of the electrolyte obtained with a NICOLET 20 SXC FTIR spectrophotometer.
    Figure 7. Design of a water purification plant by direct osmosis on a laboratory scale.
    Detailed description of the invention and some examples of realization
    The present invention allows, in a single synthesis process, to obtain a greater amount of electrolyte with great ease for its magnetic extraction, which in turn makes it possible to increase the yield of the osmosis process in desalination plants.

    The invention consists of a new nanostructured electrolyte that has a larger nanoparticle size, up to 100 nm, and that is easily separable by magnetic means. The electrolyte is based on high-magnetization iron oxide nanoparticles, close to magnetite values in the form of massive material, 90 emu / g (around 3.1 E-14 emu per nanoparticle) coated with a functional group, in particular with a polymer, polyacrylic acid, which provides high osmotic pressure (values greater than 27 atm) and that can be used as a water extractor in direct osmosis processes.
    The nanostructured electrolyte, hereinafter electrolyte, of the first aspect of the invention, consists of magnetic iron oxide nanoparticles whose core is magnetite, coated with polyacid. The electrolyte preferably has a coating between 5 and 10% by weight of the electrolyte, the nanoparticle has a size between 20 and 100 nm and a specific surface area between 70 and 23 m2 / g. Also, the electrolyte has a magnetization greater than 3.1E-14 emu per nanoparticle and its zeta potential in aqueous suspension at pH = 7 is less than -20 mV and greater than -30 mV.
    In a particular embodiment, the polyacid is composed of the union of monomers containing acid groups including at least one of the following: polyacrylic acid or its derivatives or polymethacrylic acid, understood as derivatives other polymers where polyacrylic acid blocks are included next to blocks of other polymers or polymethacrylic acid. Preferably polyacrylic acid of a molecular weight less than 3000 Da.
    In general, the higher the molecular weight of the electrolyte, the less amount is fixed to the surface of the nanoparticle, this would manifest itself in a zeta potential outside the range mentioned at pH 7 And the dispersion would be unstable with which the nanoparticles would precipitate.
    An important advantage of the electrolyte is the larger size of the nanoparticles in the
    present invention (20-100 nm) compared to those usually employed at 10 nm in other developments. The magnetic moment is two orders of magnitude greater than in the best case (see W010043914), which ensures an easy and total recovery of the material after the osmosis process. This difference is crucial because it allows easy and complete separation by using permanent low-cost magnets.

    The electrolyte has a high crystallinity of a cubic shape with well-defined faces unlike the spherical shape of nanoparticles synthesized by other methods in both aqueous and organic media, presenting a greater magnetic anisotropy that allows a better magnetic separation.
    In another particular embodiment, the electrolyte has a size distribution characterized by an average size deviation of less than 20%.
    The greater average size and the uniformity in the particle size with deviations of the average size inferior to the nanoparticles synthesized by coprecipitation in aqueous medium of other works, which present deviations greater than 40%, allow obtaining a high magnetic moment. This uniformity makes it possible to better optimize magnetic separation by avoiding the need for high magnetic fields for the retention of smaller nanoparticles. The good magnetic response is a consequence of the presence of a magnetite core (the most magnetic iron oxide) without structural defects, which does not exist in the case of nanoparticles of similar size prepared in organic media such as Q. Zhao , et al, ACS Applied Materials and Interfaces, 5, (2013), 11453
    As described above, the process of the second aspect of the invention comprises performing the following steps: a) the preparation of magnetic nanoparticles by oxidative precipitation of iron salts (11) in basic medium in the absence of oxygen, b ) heat treatment in the presence of polyacids, using high boiling solvents, greater than 200oe, and simultaneous distillation of water at a temperature between 200 -300 ° C, and c) electrolyte separation.
    The preparation of the magnetic nanoparticles of step a) can be carried out under a nitrogen or argon atmosphere.
    In a particular embodiment, the previous step a) is carried out by preparing, under a nitrogen atmosphere, a solution A comprising sodium nitrate and sodium hydroxide in degassed water and by preparing a solution B with ferrous sulfate heptahydrate in a solution of sulfuric acid. Once the two solutions are prepared, solution B is added on A under stirring at more than 300 rpm to form a solution C. Next, the suspension of formed green iron oxohydroxide is transferred, e, to a previously heated thermostatic vessel up to 90oe,

    where the temperature is maintained at 90 ° C without stirring for 20 hours. At the end of this maturation time, it is allowed to cool and the suspension is removed from the nitrogen atmosphere and the nanoparticles are separated from the suspension by decantation. Finally, the nanoparticles are dried, preferably at 200 ° C for 1 to 4 hours to remove moisture residues.
    Said mechanical agitation is preferably performed vigorously at more than 300 rpm, thus influencing the size of nanoparticles that are formed. The stirring can be magnetic or preferably mechanical.
    In another exemplary embodiment, the heat treatment of step b) is carried out by preparing a solution of polyacid in the high-boiling non-aqueous solvent (greater than 200 OC) and the subsequent addition of the nanoparticles prepared in the step a) in the polyacid solution prepared. Then, the mixture is heated using a reactor at a temperature between 200-300 oC and the water is distilled until the boiling temperature of the solvent is reached. The boiling temperature is maintained for at least 30 min and then the mixture is cooled to an ambient temperature. Finally, the electrolytes are separated from the solution by natural or magnetically assisted decantation.
    Preferably, the above heat treatment during step b3) is performed with vigorous stirring at more than 100 rpm to prevent the nanoparticles from sedimenting during coating.
    Also, the solvent must have a boiling temperature high enough for the polyacid to adhere to the nanoparticles without reacting with it but not so much that it degrades or alters the shape or size of the nanoparticles by partial dissolution.
    In a particular embodiment the solvent is triethylene glycol.
    The heat treatment can also be carried out at the temperature reached by boiling triethylene glycol even in the presence of traces of water, preferably between 200 ° C and 300 ° C, more preferably at 275 ° C. On the other hand, the weight ratios between the nanoparticles and the polyacrylic acid used are preferably 1:25 for nanoparticles of 20 nm or less and 1:15 for those larger than 20 nm.
    Example 1.-Electrolyte of obtaining and obtaining procedure.
    Preparation of magnetic nanoparticles
    5 Magnetic nanoparticles are prepared by the oxidative precipitation method of ferrous sulfate solutions in alkaline medium (M. Andrés-Vergés et al., J. Phys. D: Appl. Phys., 41, (2008), 134003) . A typical preparation procedure is as follows: In a glove box under a nitrogen atmosphere, solution A containing 34 g of sodium nitrate, 36.8 g of sodium hydroxide in 500 mL of degassed water is prepared, the solution
    10 B contains 111.21 g of ferrous sulfate heptahydrate in 200 mL of a 0.01 M solution of degassed sulfuric acid. Solution B is added on A with strong mechanical stirring and after mixing the suspension of formed green iron oxohydroxide is transferred, e, to a thermostatic vessel previously heated to 90 ° C where the suspension is left at said temperature and without stirring for 20 hours After this time is left
    15 cool and the suspension is removed from the glove box. The nanoparticles are separated by means of a magnetic separator SEPMAG500® which will also be used for successive washes (5x) of the product with distilled water.
    The product is finally dried at 200 ° C for one hour in the air to remove traces of moisture. The nanoparticles obtained correspond to those in Figure 1.
    Table 1 shows the characteristics of the magnetic nanoparticles synthesized for direct osmosis.
    Diameter (nm) Saturation Magnetization (emu / g)Volume of a nanoparticle (nm ')Mass of a nanoparticle (g)Moment per nanoparticle (emu)
    10 30523.62,67036E-188.01108E-17
    12 60904,78084,61438E-182,76863E-16
    17 412572.44681,31195E-175,37899E-16
    51 87.569456.06363,54226E-163,09948E-14
    Table 1. Characteristics of the nanoparticles obtained.
    The 50 nm nanoparticle has a smaller specific surface area (23 m 2 / g) with respect to the surface of smaller nanoparticles but with a magnetic moment two orders

    of greater magnitude (3,09948E-14 emu). The magnetic moment data have been obtained
    from the magnetization curve at room temperature, where a saturation magnetization of Ms = 87.5 emu / g and a coercivity of He = 100 Oe at room temperature was measured (Figure 2). The presence of magnetite is clear in the thermogravimetric analysis showing a mass increase with heating above 200 ° C as a result of the oxidation of magnetite to maghemite (Figure 3).
    Coating of the magnetic nanoparticles.
    Subsequently, the magnetic nanoparticles are coated with low molecular weight polyacrylic acid «3000 Da) by heating at 275 ° C under an inert atmosphere using triethylene glycol as solvent. The weight ratios nanoparticles: polyacrylic acid used were 1:25 for nanoparticles of 20 nm or less and 1:15 for those larger than 20 nm. The dispersion and coating process was done in a solution of 160 9 of polyacrylic acid in a liter of triethylene glycol in which the appropriate amount of nanoparticles obtained in step a of the process had been added. The mixture was heated with stirring using a reactor. Once the working temperature was reached, it was maintained for at least 30 min with good stirring and allowed to cool. The coated nanoparticles were separated by magnetic decantation after the addition of acetone and subjected to successive washing with water to remove the remains of the reaction.
    In the final product, the electrolyte, once dry, the amount of coating adhered was determined by means of thermogravimetric analysis, resulting in 5-10% depending on the particle size used. The coating obtained for 20 nm nanoparticles of average size was 10% by weight determined by thermogravimetry (Figure 3).
    It has been proven by studies of dynamic light scattering (DLS) that the zeta potential of the nanoparticles in aqueous suspension at pH = 7 is -30 mV instead of the near zero value of the uncoated iron oxide nanoparticles. The dependence with the pH of the nanoparticles is shown in Figure 4.
    Finally, by means of transmission electron microscopy, the homogeneity of the nanoparticles in size and shape has been observed and that the coating does not alter or dissolve the nanoparticles (Figure 5), maintaining the magnetic properties of the nanoparticles and allowing their recycling and reuse.
    Total volume (cm3) Concentrations of solution C (Mol / l)
    Elder brother, NaOHFeSO,
    2000 0.20.460.2
    It has been proven that the proposed procedure eliminates the remains of water that prevent reaching the necessary temperature (275 ° C), achieving a strong covalent bond between the polymer and the nanoparticles as indicated in the infrared spectroscopy measurements (Figure 6).
    Example 2.- Procedure for obtaining the electrolyte in large quantities in a preparation
    The procedure used in this invention has been scaled to obtain up to 20
    10 grams of nanoparticles in a synthesis, in aqueous medium and using commonly used reagents. For this reason it has been possible to test its effectiveness as a solute extractor in a plant of larger dimensions than those published so far based on solutions of up to 2 liters (Table 2). Table 2 shows the data.
    .. ..
    15 Table 2. Descapclon of the slnteslS scaled to obtain 20 grams of 50 nm nanoparticles:
    Example 3.-Use of the electrolyte in a direct osmosis process.
    In order to verify the electrolyte performance obtained in example 1, a direct osmosis water purification plant has been used on a laboratory scale (Figure 7), the plant comprises a flat membrane for direct osmosis that has a surface area of 0.014872 m2 type Cartridge Membrane (110707-ES-1) from Hydration Technology Innovations (http://www.brickform.com/products/files/MSDS-CS-700.pdfa6deMayode2014).La
    The membrane is located within a cellulose triacetate module which also comprises two 180x230x30 mm cells. The union between both cells is made by 6 through screws, three on each side of the cell. The cell through which salt water circulates has the entrance at the top and the exit at the bottom. Both ports are 9,525 mm holes. A groove has been engraved inside the plate,
    30 of 90x178x2 mm, as a channel through which water will circulate. the surface of said slit is grated from top to bottom so that the water is distributed evenly through the channel. In the plate another groove has been made, around the channel, in which
    Place an O-ring that will put pressure on the membrane and the other cell to prevent water leakage. The cell through which the electrolyte solution circulates has the entrance at the bottom and the exit at the top. Both ports are 9,525 mm holes. As in the other plate, a 90x178x2 mm slit has been made inside, shaped
    5 of channel through which the water circulates. The surface of said channel is grated from top to bottom so that water is distributed evenly through the channel.
    The water purification plant was operated using a salt water reservoir of 151 and a salt concentration of 1 -3.5% NaCI, an initial suspension volume of 10 nanoparticles of 300 ml at a concentration of 53% (160 g of electrolyte / 300 mL)% by weight. A flow of 0.7-0.8 Umin of salt water and a flow of 0.7-0.8 Llmin in electrolyte dispersion were used. The weight gain of the electrolyte dispersion was recorded by means of a scale as a function of time and of the regression lines weight versus time the water production was determined. Finished the experiment the electrolyte separated
    15 with the help of a permanent NdFeB magnet and excess water was removed from the electrolyte reservoir to return to the initial concentration. The results obtained are shown in Table 3 where the production of purified water obtained using waters of different salinity is indicated as well as its cost considering the power consumed from the plant (6W) and the cost of electricity € 0,15094 / kW / h.
    Daily production (Lid) Consumption (kWh / L)Cost (€ / L)
    xp.1 -Water Tap 74 ~ S / cm 11, 90.01210.0018
    Exp. 2 - Brackish water 16,640 ~ S / cm 9.30.01550.0023
    Exp. 3 - Water Sea 32,150 ~ S / cm 9.40.01540.0023
    ExpA -Water Sea 47.200 ~ S / cm 9.40.01530.0023
    Exp. 5 -Water Sea 47,200 ~ S / cm 9.00.01600.0024
    ..
    Table 3.-Production of purified water The scope of the invention is defined by the following set of claims.
    权利要求:
    Claims (13)
    [1]
    1.-Nanostructured electrolyte, characterized in that it is composed of magnetic iron oxide nanoparticles whose core is magnetite coated with polyacids in
    5 solid state, where:
    - the polyacid constitutes a weight percentage of between 5 and 10% of the electrolyte;-the nanoparticles have a size between 20 and 100 nm and a surfacespecific between 70 and 23 mZlg;-the electrolyte has a magnetization greater than 3.1 E-14 emu / electrolyte; Y
    10 -the zeta potential of the eleclrolite in aqueous suspension at pH = 7 is less than -20 mV and greater than -30 mV.
    [2]
    2. Electrolyte according to claim 1, characterized in that the polyacid is composed
    by binding monomers containing acid groups including at least acid
    15 polyacrylic or its derivatives or polymethacrylic acid.
    [3]
    3.-Electrolyte according to claim 2, characterized in that the polyacid is acidic
    polyacrylic molecular weight less than 3000 Da
    20 4.-Electrolyte according to any of claims 1 to 3, characterized in that the
    electrolyte comprises a deviation of the average size of less than 20%.
    [5]
    5.-Procedure for obtaining a nanostructured electrolyte according to any one of
    claims 1 to 4, characterized in that it comprises the following steps: a) preparing magnetic nanoparticles whose core is magnetite by oxidative precipitation of iron salts (11) in a basic medium in the absence of oxygen; b) heat treat, in the presence of polyacids and in the presence of a non-solvent
    aqueous boiling point greater than 200 ° C in nitrogen atmosphere, said
    magnetic nanoparticles and proceed to a simultaneous distillation of water at a
    30 temperature between 200 -300 ° C; And c) separate the electrolyte.
    [6]
    6. Method according to claim 5, characterized in that step a) comprises the
    following steps: 35 a1) prepare under nitrogen a solution A containing sodium nitrate, sodium hydroxide in degassed water;
    a2) prepare a solution B with ferrous sulfate heptahydrate in a solution
    sulfuric acid;a3) add solution B on A under stirring at more than 300 rpm;a4) transfer the green iron oxohydroxide suspension, e, formed in theprevious stage a3), to a previously heated thermostatic vessel up to 900eleaving the suspension at said temperature and without stirring for more than 20 hours;a5) extract the cold suspension from the nitrogen atmosphere;a6) separating the nanoparticles from the suspension; Ya7) Dry the nanoparticles to remove traces of moisture.
    [7]
    7. Method according to claim 6, characterized in that it comprises drying in step a7) at 200 ° C for 1 to 4 hours.
    [8]
    8. Method according to any of claims 5 to 7, characterized in that the
    step b) comprises the following steps: b1) preparing a solution of polyacid in a non-aqueous solvent of boiling point greater than 200 ° C;
    b2) adding the nanoparticles prepared in step a) to said solution ofprepared polyacid;b3) heat the mixture obtained in step b2) using a reactor with stirring aa temperature between 200 -300 oC;b4) distill the water until the boiling temperature of the solvent is reached;b5) maintain the boiling temperature for at least 30 min andb6) cool to room temperature.
    [9]
    9. Process according to claim 8, characterized in that the non-aqueous solvent is triethylene glycol.
    [10]
    10. Method according to claim 9, characterized in that the boiling temperature of the non-aqueous solvent is between 200 and 300 ° C.
    [11]
    11. Method according to claim 10, characterized in that the weight ratios
    nanoparticle / poly acrylic acid used are 1: 25 for nanoparticles of 20 nm or less and 1: 15 for nanoparticles larger than 20 nm.
    [12]
    12. Method according to any of claims 8 to 11, characterized in that
    The electrolytes in the solution are separated by the addition of acetone by means of a
    magnetic separator.
    [13]
    13. Use of the electrolyte defined in any one of claims 1 to 4 in direct osmosis processes.
    [14]
    14. Use according to claim 13 in desalination systems.
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    同族专利:
    公开号 | 公开日
    WO2015177391A1|2015-11-26|
    ES2554578B1|2016-09-28|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    WO2011099941A1|2010-02-10|2011-08-18|National University Of Singapore|Forward osmosis process using hydrophilic magnetic nanoparticles as draw solutes|
    KR101211376B1|2010-09-30|2012-12-13|한국에너지기술연구원|Fischer-tropsch bubble column reactor feasible multi reaction|WO2018104957A1|2016-12-09|2018-06-14|Arvind Envisol Ltd.|Anionic nanoparticle system for desalination and method thereof|
    CN110049950A|2016-12-09|2019-07-23|阿瓦恩德因维索有限公司|The synthesis devices and methods therefor of nanoparticle system for desalination|
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    PCT/ES2015/070391| WO2015177391A1|2014-05-19|2015-05-18|Nanostructured electrolyte useful for direct osmosis desalination, method for obtaining the electrolyte and uses of same|
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