• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Photocatalytic composite material and its use. The present invention refers to a new photocatalytic composite material of TiO2/glass formed by nanoparticles of TiO2, preferably of anatase, with a small proportion of low point inorganic glass fusion that acts as a binder for the nanoparticles, replacing the traditional polymeric binders. The photocatalytic composite of the invention can be used in paints and coatings, as well as in the manufacture of compact materials for construction. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2837526A1
    申请号:ES201931171
    申请日:2019-12-30
    公开日:2021-06-30
    发明作者:Corral Jose Serafin Moya；Garcia Carlos Pecharroman；ALVAREZ Mª BELEN CABAL；Valdes Adolfo Fernandez；Esteban Sonia Lopez
    申请人:Consejo Superior de Investigaciones Cientificas CSIC；
    IPC主号:
    专利说明:

    [0002] Photocatalytic composite material and its use
    [0004] TECHNICAL SECTOR
    [0006] The present invention relates to a new photocatalytic composite material based on TIO2 nanoparticles, preferably as Ti02-Anatase, and low melting point glass, as well as its use as an additive in paints and coatings and in building materials.
    [0008] STATE OF THE ART
    [0010] Today, TIO2 is the world's leading pigment for whiteness, gloss and opacity, and its use is widespread in paints. For its fixation, the presence of binding materials, generally of an organic nature, is essential. However, when titanium dioxide absorbs UV light, a chain of events begins that leads to the production of free radicals. These radicals can attack the surroundings of the pigment, which can cause decomposition of the organic medium, resulting in brittleness, loss of gloss, loose dust, etc. and, in the case of paints, when pigments or colorants are involved, the color can also be affected, giving rise to a yellowish color [A quick assessment of the photocatalytic activity of TÍO2 pigments-From lab to conservaron studio, B.A. van Driel, Microchemical Journal 126, 2016, 162-171],
    [0012] It is known that the efficiency of TIO2 photocatalytic reactions increases when its particles are nanometric in size, since they expose more surface area per unit volume than the mass equivalent with micrometer-sized particles. However, the use of TIO2 nanoparticles is limited on the one hand by their tendency to agglomerate, making their incorporation and homogeneous dispersion difficult when it is incorporated as an additive in different systems and on the other, due to their toxicity [Toxicity of TÍO2 nanoparticles on the NRK52E renal cell line, Mol Cell Toxicol (2017) 13: 419-431], to the point that they are considered carcinogenic to humans when inhaled. Likewise, they present a proven toxicity in vertebrates, invertebrates, plants and algae, with the consequent risk to health and environmental impact [Toxicity and mechanisms of action of titanium dioxide nanoparticles in living organisms, J. Hou et al, Journal of Environmental Sciences, 75 (2019) 40-53)]. This problem is especially relevant in the case of anatase, a crystallographic form of TIO2 that is more stable when the particle size of TIO2 is between 10-20 nm, since it has a greater capacity as a photocatalyst than rutile, the crystallographic form of Ti02, which is more thermodynamically stable under ambient conditions [Why is anatase a better photocatalyst than rutile - Model studies on epitaxial Ti02 films. T. Luttrell et al., Scientific Reports, 4: 4043, 2014], In the case of paints, this higher photocatalytic activity of anatase is, a priori, negative, since it has a greater capacity to create free radicals in the binder , with the consequent degradation of it. This is why rutile is commonly used in paint formulations instead of anatase.
    [0014] Currently there are methods to reduce this activity as an initiator of the degradation of binders [Self-cleaning materials on Architecture1 Heritage: Compatibility of photo-induced hydrophilicity of TÍO2 coatings on stone surfaces, Quagliarini, E., Bondioli, F., Goffredo , GB, Licciulli, A., Munafo, P., Journal of Cultural Heritage, 14 (1) pp. 1-7, 2013], but they add an added difficulty to their preparation, so that the use of anatase in paints is limited to only some special applications in which self-cleaning is required (protection of architectural pieces, etc.).
    [0016] A possible solution to avoid the agglomeration of the TIO2-Anatase nanoparticles while allowing their use in paints without degrading them is to support said nanoparticles on an inorganic substrate. In this sense, the use of substrates such as metal oxides and clays is known, as described in document ES2401799, in which reference is made to a method to support TIO2 particles, which can be anatase, on sepiolite or attapulgite to be used in paints.
    [0018] On the other hand, the use of inorganic supports to achieve an isolated distribution of Ti02-anatase nanoparticles has been investigated in microwave devices where TIO2 provides very favorable properties at microwave frequencies. This is the case in composites formed by low melting point glasses and Ti02-anatase [Jobin Varghese, Prasadh Ramachandran, Maciej Sobocinski, Timo Vahera, and Heli Jantunen. ACS Sustainable Chemistry & Engineering 20197 (4), 4274-4283] for applications in the electronics industry. However, these glasses contain lead, a material whose repeated exposure can have serious and irreversible effects on neurological behavior and development, particularly in children. This problem derived from the use of lead has led the European Union to regulate the marketing and use of products containing this element through Regulation (EU) 2015/628 of April 22, 2015. It is therefore a chemical element which is to be avoided as far as possible.
    [0020] The present invention solves the problems of using Ti02-anatase nanoparticles as a photocatalytic additive by using a low melting point glass as a binder described by the inventors in [Synthesis, characterization and applications of low temperature melting glasses belonging to P20sCa0Na20 system , W. Liu et al, Ceramics International, 45, 9, 2019, 12234 12242], which, unlike commonly used low-melting point glasses, does not contain lead and allows said nanoparticles to remain dispersed and non-agglomerated.
    [0022] DESCRIPTION OF THE INVENTION
    [0024] The inventors have discovered a new composite material that can be used as an additive in the preparation of paints and coatings with high photocatalytic capacity from Ti02-anatase nanoparticles instead of Ti02-rutile.
    [0025] The additive is obtained by mixing the Ti02-anatase nanoparticles homogeneously with a small proportion of inorganic glass with a low melting point that replaces the traditional polymeric binders.
    [0027] In the present invention, a "nanoparticle" is understood to mean a particle with a size between 1 and 100 nm. The size of the nanoparticles has been measured by Transmission Electron Microscopy (JEOL, 2000 EX-II).
    [0029] In the present invention, "photocatalytic material" is understood as a semiconductor material that is activated by radiation of energy equal to or greater than that corresponding to "bandgap" or "band gap", giving rise to a hole / electron that can react with the water, forming highly reactive OH- radicals on the surface of the semiconductor, which can subsequently react with the organic compounds to be degraded.
    [0031] Once the additive has been added to the paint, it can be applied to the desired surface and then subjected to local heating at 500oC in situ by any of the conventional technologies available on the market (laser, torch, gas burner, etc. ) for the glass to flow, coating the TIO2 particles and "curing" the paint.
    [0033] The composite Ti02-anatase / Glass of the invention can in this way be handled and applied without any risk to human health or the environment since the nanoparticles are supported in the glass and are not released into the environment. The use of a low melting point glass as a binder, instead of using organic materials, allows the use of the additive in paints, coatings, or in the form of compact material without them suffering a deterioration in their properties.
    [0035] The use of the inorganic additive (glass) of the invention allows incorporating different advantages to the paint:
    [0036] a) The degradation of conventional paints by decomposition of the organic component is avoided, a process that gives rise to an unwanted yellowish color.
    [0037] b) Provides self-cleaning capacity to the new paint, helping to remove carbon (C and NOx, organic matter) produced by atmospheric pollution. In the same way it would also be possible graffiti, unwanted graffiti that could appear on different surfaces.
    [0039] The inventors have also discovered that the composite material of the invention can also be used to manufacture compact construction materials such as tiles, tiles, etc., for covering specific rooms or enclosures where self-cleaning is required.
    [0041] In this way, the object of the present invention is a photocatalytic composite material that consists of a matrix of nanoparticles of TIO2 in which a glass is dispersed, where the glass is characterized because it belongs to the P20s-Ca0 -M system, where M can be LÍ2O, Na2Ü, K2O or a combination thereof, it has a P2O5 content of 45% mol., A CaO content between 10 and 15% mol. and a content of M between 40 and 45% mol.
    [0043] Glasses with the composition described have a low melting point, in particular, they have a melting point below 600oC.
    [0045] In a particular embodiment of the invention, the glass content in the composite material is less than 25% by volume, and more preferably less than 5% by volume. This low glass content allows the composite material to have excellent photocatalytic properties. For any embodiment, the minimum glass content in the material is preferably 0.5% by volume.
    [0047] The glass is homogeneously dispersed in the Ti02 nanoparticle matrix.
    [0048] In a particular embodiment of the invention, at least 79% by weight of TIO2 is Ti02-anatase.
    [0050] The material of the present invention is prepared by mixing HO2 powder and glass in a mortar until a homogeneous mixture is obtained. Subsequently, the mixture is pressed in a die to form a tablet, preferably in a 1-ton uniaxial press, which is heated in an oven at 10 ° C / min up to 500 ° C, without room, and cooling to room temperature.
    [0052] During the heating cycle that the composite material is subjected to in the oven, the glass reaches its softening temperature, wetting the surface of the TIO2 nanoparticles.
    [0054] The inventors have verified by X-ray diffraction (Figure 1) that, at the softening temperature of the glass, anatase retains its crystalline morphology, and a transformation from anatase to rutile of only 4% -5% by weight occurs. , so the photocatalytic properties of the composite material are not affected compared to TIO2 without glass.
    [0056] Another aspect of the invention relates to the use of the photocatalytic composite material described in the first aspect of the invention as a photocatalyst.
    [0058] A preferred embodiment relates to the use of the photocatalytic composite material described in the first aspect of the invention as a photocatalyst additive in paints, coatings or building materials.
    [0060] DESCRIPTION OF THE FIGURES
    [0062] Fig. 1. RX diffractograms of the sample Ti02 / 5% vol. glass: (a) before heating and (b) after heating to 500oC.
    [0063] Fig. 2. Comparison of the evolution of the degradation of methylene blue projected on pure TIO2, and on compacted tablets of Ti02 / 1% vol. glass, Ti02 / 3% vol. glass and Ti02 / 5% vol. glass.
    [0065] Fig. 3. Detail of the degradation of methylene blue on the tablet of the compound Ti02 / 5% vol. glass under exposure to ultraviolet radiation of 380 nm.
    [0067] EXAMPLES OF REALIZATION
    [0068] The following example is presented as an additional guide for the average person skilled in the art and should in no way be construed as a limitation of the invention.
    [0070] Example 1.- Preparation of photocatalytic tablets of TIO 2 -Anatase nanoparticles and low melting point glass according to the present invention.
    [0072] A low melting point glass belonging to the P20s-Ca0-Na20 system and composition 45 mol% P2O5, 10 mol% CaO, 45 mol% Na20 (45P10C45N) obtained by a fusion process from the precursors (NH4H2PO4, CaC03 and Na2C03). The precursors were thoroughly mixed in the proportion suitable for the composition. The heat treatment was carried out in two stages in a 10% Pt / Rh crucible. In the first stage, the mixture of precursors was treated at 350 ° C for 1 h to promote their decomposition. In the second stage the resulting mixture was treated at 900 ° C for 1 hr and quenched. The cooled glass frit was ground in agate mortar and sieved to obtain a particle size below 45 pm. This glass preparation has been previously described in: Synthesis, characterization and applications of low temperature melting glasses belonging to P20 sCa0 Na20 system, W. Liu et al, Ceramics International, 45, 9, 2019, 12234-12242
    [0074] Pure commercial TIO2 powder (Aeroxide® TIO2 P 25, from the company TOLSA SA) was used. This commercial compound contains mostly anatase, and a small proportion of rutile (see, for example, Figure 1).
    [0075] The TIO2 and glass powders were mixed in the appropriate proportion (1%, 3% and 5% vol. Glass) and passed through mortar, until obtaining a homogeneous powder.
    [0077] Finally, a die and a 1 ton uniaxial press were used to obtain the tablets. The tablets were subsequently subjected to heating in an oven at 10 ° C / min up to 500 ° C, without room, and cooling to room temperature.
    [0079] Methylene blue was applied with a spray gun on the surface of the samples and the degradation of methylene blue by photocatalysis on them, as well as of the pure TIO2 tablet, was studied under the application of ultraviolet light (380 nm) for different periods of time, from fractions of a minute to periods of 2.6 hours (Figure 2). The resulting degradation slope in all cases turned out to be the same, thus demonstrating that the photocatalytic capacity of TIO2 is not altered by the presence of glass. In Figure 3 the degradation of methylene blue on the tablet of the compound Ti02 / 5% vol is specifically shown. glass.
    [0081] The measurement of the BET surface of the tablets heated to 500oC of TIO2 and Ti02 / 5% vol was also carried out. made from the adsorption-adsorption isotherms of N2 at -1960C, Micromeritics ASAP 2420 equipment). It is concluded that the BET surface is reduced by only 15% with the presence of glass, which justifies that the photocatalytic properties of TIO2 are hardly affected.
    [0083] Table 1. BET surface.
    [0085]
    [0088] The biaxial flexural strength of TIO2 discs and Ti02 / glass composite materials with different glass contents (1%, 3% and 5% vol., Respectively) was evaluated in a universal machine (Shimadzu Auto Graph AG-X5kN, Japan). Resistance was measured using the piston method on 3 balls, spaced 120 ° apart in a 10 mm diameter circle. The tests were carried out at room temperature at a crosshead speed of 0.5 mm / min. For this method, samples of 16 mm diameter and thickness between 1.2 and 1.8 mm were used.
    [0090] The resistance of the pure TIO2 is of the order of 10 MPa, and increases with the glass content, until reaching approximately twice the resistance in the compound Ti02 / 5% vol. glass. Therefore, glass improves the mechanical properties of pure TIO2. Glass plays the role of cement for the TIO2 particles.
    [0092] Table 2. Flexural strength.
    [0094]
    权利要求:
    Claims (6)
    [1]
    1. Photocatalytic composite material consisting of a matrix of TIO2 nanoparticles in which a glass is dispersed, where the glass is characterized by:
    - belongs to the P2Os-CaO-M system, where M can be Li20, Na20, K20 or a combination thereof and
    - It has a content of P2Os of 45% mol., a content of CaO between 10 and 15% mol. and a content of M between 40 and 45% mol.
    [2]
    2. Photocatalytic composite material according to claim 1 wherein at least 79% by weight of Ti02 is Ti02-anatase.
    [3]
    3. Photocatalytic composite material according to any of claims 1 2 wherein the percentage of glass is less than 25% by volume.
    [4]
    4. Photocatalytic composite material according to claim 3 where the percentage of glass is less than 5% by volume.
    [5]
    5. Use of the photocatalytic composite material described in any of claims 1-4 as a photocatalyst.
    [6]
    6. Use of the photocatalytic composite material according to claim 5 as a photocatalyst additive in paints, coatings or construction materials.
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    同族专利:
    公开号 | 公开日
    WO2021136857A1|2021-07-08|
    ES2837526B2|2021-11-02|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US20050119105A1|2002-01-18|2005-06-02|Schott Ag|Glass-ceramic composite containing nanoparticles|
    法律状态:
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    优先权:
    申请号 | 申请日 | 专利标题
    ES201931171A|ES2837526B2|2019-12-30|2019-12-30|PHOTOCATALYTIC COMPOSITE MATERIAL AND USE OF THE SAME|ES201931171A| ES2837526B2|2019-12-30|2019-12-30|PHOTOCATALYTIC COMPOSITE MATERIAL AND USE OF THE SAME|
    PCT/ES2020/070790| WO2021136857A1|2019-12-30|2020-12-14|Composite photocatalytic material and uses thereof|
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