A composite photocatalytic material and its preparation method

Abstract

This invention discloses a composite photocatalytic material and its preparation method. The composite photocatalytic material comprises: basic magnesium sulfate and a photocatalyst. The basic magnesium sulfate is an irregular cementitious body of 5Mg(OH)2·MgSO4·7H2O. The photocatalyst includes TiO2, ZnO, CuO, SnO2, FeO, Fe2O3, MnO, CoO, NiO, Bi2O3, WO3, CeO2, etc. The preparation method comprises: uniformly mixing the photocatalyst, an organic weak acid, and an aqueous solution of magnesium sulfate to form a mixed slurry; uniformly mixing active magnesium oxide and a nucleating agent to form a mixed powder; then uniformly mixing the powder with a pore-forming agent and the mixed slurry, followed by reaction molding to obtain the composite photocatalytic material. The composite photocatalytic material provided by this invention is easy to mold, has good mechanical strength, and maintains good photocatalytic activity, which can solve the problem of the difficulty in recycling existing powder photocatalytic materials.

Description

Technical Field

[0001] This invention relates to a catalytic material, and more particularly to a composite photocatalytic material and its preparation method, belonging to the field of photocatalytic material technology. Background Technology

[0002] Photocatalytic oxidation involves irradiating a semiconductor material with a specific electronic structure using a light source of a certain wavelength. Electrons in the material absorb photons and are excited from the valence band to the conduction band, creating holes in the valence band. These holes then generate highly oxidizing free radicals, which react with organic pollutants in a redox reaction, ultimately oxidizing the pollutants into carbon dioxide, water, etc., thus achieving the green removal of organic pollutants. Because photocatalytic oxidation technology has unparalleled advantages over other treatment technologies, such as mild reaction conditions, simple operation, low energy consumption, no secondary pollution, and the ability to mineralize organic matter, it shows great application potential in the treatment of organic pollution.

[0003] Commonly used photocatalysts are transition metal oxides, such as TiO2, ZnO, CuO, SnO2, FeO, Fe2O3, MnO, CoO, NiO, Bi2O3, WO3, and CeO2. TiO2 has a band gap of approximately 3.0-3.2 eV, uses ultraviolet light as its excitation source, and exhibits good chemical stability and resistance to photochemical corrosion. ZnO has a band gap of 3.37 eV, primarily absorbs ultraviolet light, and is less expensive than TiO2. CuO has a band gap of approximately 1.2-2.17 eV, with high absorption and utilization of visible light, even reaching the infrared region. SnO2 has a band gap of approximately 3.6 eV, uses ultraviolet light as its excitation source, and possesses advantages such as long-term stability, high oxidation potential, chemical inertness, and corrosion resistance. FeO has a band gap of approximately 2.4 eV and can absorb visible light. Fe2O3 has a band gap of approximately 2.3 eV and exhibits good absorption of visible light. MnO has a band gap of 3.6 eV and is excited by ultraviolet light. CoO has a band gap of 2.6 eV and exhibits good absorption of visible light. NiO has a band gap of 3.5 eV and is excited by ultraviolet light. Bi₂O₃ has a band gap of 2.8 eV and exhibits good absorption of visible light. WO₃ has a band gap between 2.5 and 3.0 eV and responds well to sunlight. CeO₂ has a band gap of approximately 3.2 eV and is excited by ultraviolet light.

[0004] However, these photocatalytic materials are mostly in powder form, and their use and recycling are often difficult when applied to the removal of pollutants in the environment, thus limiting their large-scale application. Summary of the Invention

[0005] The main objective of this invention is to provide a composite photocatalytic material and its preparation method to solve the problem that existing powder photocatalytic materials are difficult to recycle and reuse.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] This invention provides a composite photocatalytic material comprising: basic magnesium sulfate and a photocatalyst, wherein the basic magnesium sulfate is an irregular cementitious body of 5Mg(OH)2·MgSO4·7H2O, and the photocatalyst comprises any one or a combination of two or more of TiO2, ZnO, CuO, SnO2, FeO, Fe2O3, MnO, CoO, NiO, Bi2O3, WO3, and CeO2.

[0008] In some preferred embodiments, the composite photocatalytic material comprises the following components in parts by mass: 50-98 parts basic magnesium sulfate and 2-50 parts photocatalyst.

[0009] This invention also provides a method for preparing a composite photocatalytic material, comprising:

[0010] A photocatalyst, an organic weak acid, and a magnesium sulfate aqueous solution are uniformly mixed to prepare a mixed slurry.

[0011] Active magnesium oxide and nucleating agent are uniformly mixed to form a mixed powder;

[0012] The mixed powder, pore-forming agent and mixed slurry are mixed evenly, and then reacted and shaped to obtain the composite photocatalytic material.

[0013] This invention also provides a composite photocatalytic material prepared by the aforementioned method.

[0014] Compared with existing photocatalytic materials, the beneficial effects of the present invention are at least as follows:

[0015] The composite photocatalytic material provided by this invention is easy to mold, has good mechanical strength, and still maintains good photocatalytic activity, which can solve the problem that existing powder photocatalytic materials are difficult to recycle and reuse. Detailed Implementation

[0016] In view of the shortcomings of the prior art, the inventors of this case, through long-term research and extensive practice, have proposed the technical solution of the present invention, which mainly provides a previously unreported composite photocatalytic material containing basic magnesium sulfate.

[0017] The main concept of this invention lies in the fact that basic magnesium sulfate is an environmentally friendly air-hardening gel material with good water and salt resistance, stable physicochemical properties, and easy molding. Currently, there are no reports on the application of basic magnesium sulfate in the development of composite photocatalytic materials. Therefore, the inventors of this invention innovatively apply basic magnesium sulfate to the preparation of composite photocatalytic materials.

[0018] The following will provide a further explanation of the technical solution, its implementation process, and its principles.

[0019] As one aspect of the present invention, a composite photocatalytic material is provided, comprising basic magnesium sulfate and a photocatalyst, wherein the basic magnesium sulfate is an irregular cementation of 5·1·7 whiskers (5Mg(OH)2·MgSO4·7H2O), and the photocatalyst comprises any one or a combination of two or more of TiO2, ZnO, CuO, SnO2, FeO, Fe2O3, MnO, CoO, NiO, Bi2O3, WO3, CeO2, etc.

[0020] In a preferred embodiment, the content of the basic magnesium sulfate component in the composite photocatalytic material is 50-98 parts by mass, and the content of the photocatalyst component is 2-50 parts.

[0021] Furthermore, the mechanical strength of the composite photocatalytic material can reach 0.4 MPa or higher, preferably 0.4 to 1 MPa.

[0022] In another aspect, this invention provides a method for preparing a composite photocatalytic material, comprising:

[0023] A photocatalyst, an organic weak acid, and a magnesium sulfate aqueous solution are uniformly mixed to prepare a mixed slurry.

[0024] Active magnesium oxide and nucleating agent are uniformly mixed to form a mixed powder;

[0025] The mixed powder, pore-forming agent and mixed slurry are mixed evenly, and then reacted and shaped to obtain the composite photocatalytic material.

[0026] In some preferred embodiments, the preparation method specifically includes the following steps:

[0027] (1) Mix the powdered photocatalyst, the organic weak acid and the magnesium sulfate aqueous solution to make a uniform slurry;

[0028] (2) Mix active magnesium oxide and nucleating agent to form a uniformly mixed powder;

[0029] (3) After the mixed powder and pore-forming agent are added to the mixed slurry and stirred thoroughly and mixed evenly, the mixture is reacted and shaped in the mold to obtain the composite photocatalytic material.

[0030] The preparation principle of the present invention may be as follows: (1) In magnesium sulfate solution, the metal oxide is surface activated and fully dispersed under the action of organic weak acid; (2) The nucleating agent and active magnesium oxide are fully mixed to facilitate the full occurrence of nucleation reaction and rapid mass transfer; (3) Magnesium oxide reacts with water to form hydroxide ions, and magnesium sulfate reacts with hydroxide ions under the induction of nucleating agent to generate 5·1·7 phase, while growing eutectic with metal oxide, and solidifying and forming under the action of pore-forming agent.

[0031] In some preferred embodiments, in step (1), the photocatalyst includes any one or a combination of two or more of TiO2, ZnO, CuO, SnO2, FeO, Fe2O3, MnO, CoO, NiO, Bi2O3, WO3, CeO2, etc.

[0032] In some preferred embodiments, in step (1), the weak organic acid includes carboxylic acid R(COOH). n Hydroxycarboxylic acid HOR(COOH) n The composition comprises any one or a combination of two of the following, wherein R is a hydrocarbon group, n is an integer greater than or equal to 1, and the mass fraction is 0.5 to 5 parts. The addition of the weak organic acid in this invention serves two purposes: first, it provides a certain amount of hydrogen ions, which react with the metal oxide to activate its surface, promoting the eutectic growth of 5.1.7 whiskers and the metal oxide, ensuring the charge conduction performance of the material, and ensuring that the metal oxide is uniformly and firmly dispersed; second, the organic acid anions adsorb on the magnesium oxide surface, inhibiting the formation of magnesium hydroxide and promoting the growth of the 5.1.7 phase.

[0033] Furthermore, the organic weak acid can be any one or a combination of two or more of formic acid, itaconic acid, malic acid, tannic acid, salicylic acid, succinic acid, gluconic acid, lactic acid, maleic acid, glucoheponic acid, etc., but is not limited to these.

[0034] In some preferred embodiments, the preparation of the magnesium sulfate aqueous solution in step (1) includes: mixing magnesium sulfate with water to obtain the magnesium sulfate aqueous solution. The magnesium sulfate is present in a mass fraction of 5–25 parts, and the water is present in a mass fraction of 50–89.5 parts.

[0035] Furthermore, the powdered photocatalyst in the mixed slurry is 5 to 20 parts by mass.

[0036] In some preferred embodiments, the mixed slurry comprises the following components in parts by weight: 0.5 to 5 parts of a weak organic acid, 5 to 25 parts of magnesium sulfate, 5 to 20 parts of a photocatalyst, and 50 to 89.5 parts of water.

[0037] In some preferred embodiments, in step (2), the nucleating agent comprises powdered basic magnesium sulfate, wherein the basic magnesium sulfate is 5·1·7 whiskers (5Mg(OH)2·MgSO4·7H2O).

[0038] In some preferred embodiments, in step (2), the mass ratio of the nucleating agent to the active magnesium oxide is 5-15:85-95, that is, in other words, the mass fraction of the nucleating agent is 5-15 parts and the mass fraction of the active magnesium oxide is 85-95 parts.

[0039] In some preferred embodiments, in step (3), the pore-forming agent includes any one or a combination of two or more of hydrogen peroxide, surfactants, protein liquid (such as egg white liquid), etc., but is not limited thereto.

[0040] Furthermore, the surfactant may be any one or a combination of two or more of sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium lignosulfonate, calcium stearate, polyvinyl alcohol, lauroyl glutamic acid, sodium octadecyl sulfate, hexadecyltrimethylammonium bromide, etc., but is not limited thereto.

[0041] In some preferred embodiments, in step (3), the mass ratio of the mixed powder, the pore-forming agent and the mixed slurry is (20-50):(0.5-5):(45-79.5), that is, from another perspective, the mass fraction of the pore-forming agent is 0.5-5 parts, the mass fraction of the mixed powder is 20-50 parts, and the mass fraction of the mixed slurry is 45-79.5 parts.

[0042] In some preferred embodiments, the reaction molding temperature is room temperature, the time is basically maintained at more than 24 hours, and it is aged for more than 2 days before it can be used.

[0043] Accordingly, another aspect of the present invention provides a composite photocatalytic material prepared by the aforementioned preparation method.

[0044] Furthermore, another aspect of the present invention provides the application of the aforementioned composite photocatalytic material in the field of photocatalytic degradation. For example, the composite photocatalytic material can be used to catalytically degrade tetracycline hydrochloride, methyl orange, etc., but is not limited thereto.

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be further described in detail below with reference to several preferred embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. For test methods in the following embodiments where specific conditions are not specified, the test methods in the embodiments are all performed under conventional conditions. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0046] All reagents used in the following examples are of analytical grade.

[0047] Example 1

[0048] The preparation process of basic magnesium sulfate-TiO2 composite photocatalytic material is as follows:

[0049] (1) Mix 5 parts of powdered TiO2, 0.5 parts of formic acid, 5 parts of magnesium sulfate, and 89.5 parts of water, and stir thoroughly to make a uniform slurry;

[0050] (2) Mix 85 parts of active magnesium oxide and 15 parts of powdered basic magnesium sulfate 5·1·7 (5Mg(OH)2·MgSO4·7H2O) and stir thoroughly to make a uniform mixed powder.

[0051] (3) Add 20 parts of mixed powder and 0.5 parts of 30% hydrogen peroxide to 79.5 parts of mixed slurry, stir thoroughly and mix quickly and evenly, then package into 4cm×4cm×1cm molds to react and form, and obtain basic magnesium sulfate-TiO2 composite sheets.

[0052] Tests showed that the basic magnesium sulfate-TiO2 composite sheet obtained in this embodiment has a compressive strength of 0.5 MPa. Under specific conditions of irradiation for 2 hours under a light source of 280-380 nm, it can degrade 42.3% of tetracycline hydrochloride (100 mg / L) and 65.1% of methyl orange (100 mg / L).

[0053] Example 2

[0054] The preparation process of basic magnesium sulfate-ZnO composite photocatalytic material is as follows:

[0055] (1) Mix 20 parts powdered ZnO, 5 parts itaconic acid, 10 parts magnesium sulfate, and 65 parts water, and stir thoroughly to make a uniform slurry.

[0056] (2) Mix 95 parts of active magnesium oxide and 5 parts of powdered basic magnesium sulfate 5·1·7 (5Mg(OH)2·MgSO4·7H2O) and stir thoroughly to make a uniform mixed powder.

[0057] (3) Add 50 parts of mixed powder and 5 parts of sodium dodecylbenzenesulfonate to 45 parts of mixed slurry, stir thoroughly and mix quickly and evenly, then pack into 4cm×4cm×4cm molds for reaction molding, grind and pass through 5-60 mesh sieves to obtain basic magnesium sulfate-ZnO composite particles.

[0058] Tests showed that the basic magnesium sulfate-ZnO composite particles obtained in this embodiment have a compressive strength of 0.4 MPa. Under specific conditions of irradiation for 2 hours under a light source of 280-380 nm, they can degrade 40.5% of tetracycline hydrochloride (100 mg / L) and 58.2% of methyl orange (100 mg / L).

[0059] Example 3

[0060] The preparation process of basic magnesium sulfate-Bi2O3 composite photocatalytic material is as follows:

[0061] (1) Mix 10 parts of powdered Bi2O3, 2.5 parts of malic acid, 15 parts of magnesium sulfate, and 72.5 parts of water, and stir thoroughly to make a uniform slurry;

[0062] (2) Mix 90 parts of active magnesium oxide and 10 parts of powdered basic magnesium sulfate 5·1·7 (5Mg(OH)2·MgSO4·7H2O) and stir thoroughly to make a uniform mixed powder.

[0063] (3) Add 40 parts of the mixed powder and 4 parts of sodium lauryl sulfate to 56 parts of the mixed slurry, stir thoroughly and mix quickly until uniform, then dispense into 4cm containers. 2 The reaction was carried out in a 0.5cm mold to obtain a basic magnesium sulfate-Bi2O3 composite sheet.

[0064] Tests showed that the basic magnesium sulfate-Bi2O3 composite sheet obtained in this embodiment has a compressive strength of 0.7 MPa. Under specific conditions of irradiation for 2 hours under a light source of 280-460 nm, it can degrade 67.5% of tetracycline hydrochloride (100 mg / L) and 88.6% of methyl orange (100 mg / L).

[0065] Example 4

[0066] The preparation process of basic magnesium sulfate-WO3 composite photocatalytic material is as follows:

[0067] (1) Mix 12 parts of powdered WO3, 3 parts of tannic acid, 10 parts of magnesium sulfate, and 75 parts of water, and stir thoroughly to make a uniform slurry.

[0068] (2) Mix 90 parts of active magnesium oxide and 10 parts of powdered basic magnesium sulfate 5·1·7 (5Mg(OH)2·MgSO4·7H2O) and stir thoroughly to make a uniform mixed powder.

[0069] (3) Add 35 parts of the mixed powder and 2 parts of egg white liquid to 63 parts of the mixed slurry, stir thoroughly and mix quickly until uniform, then dispense into 4cm containers. 2 The reaction is carried out in a 0.5cm mold to obtain a basic magnesium sulfate-WO3 composite sheet.

[0070] Tests showed that the basic magnesium sulfate-WO3 composite sheet obtained in this embodiment has a compressive strength of 0.6 MPa. Under specific conditions of irradiation for 2 hours under a light source of 280-600 nm, it can degrade 82.5% of tetracycline hydrochloride (100 mg / L) and 93.6% of methyl orange (100 mg / L).

[0071] Example 5

[0072] The preparation process of basic magnesium sulfate-CuO / SnO2 composite photocatalytic material is as follows:

[0073] (1) Mix 15 parts of powdered CuO, 5 parts of powdered SnO2, 3 parts of salicylic acid with 15 parts of magnesium sulfate and 73 parts of water, stir thoroughly, and make a uniform slurry.

[0074] (2) Mix 95 parts of active magnesium oxide and 5 parts of powdered basic magnesium sulfate 5·1·7 (5Mg(OH)2·MgSO4·7H2O) and stir thoroughly to make a uniform mixed powder.

[0075] (3) Add 40 parts of the mixed powder and 5 parts of sodium lignosulfonate to 55 parts of the mixed slurry, stir thoroughly and mix quickly until uniform, then dispense into 4cm containers. 2 The reaction is shaped in a 0.5cm mold, ground, and passed through a 5-60 mesh sieve to obtain basic magnesium sulfate-CuO / SnO2 composite particles.

[0076] Tests showed that the basic magnesium sulfate-CuO / SnO2 composite particles obtained in this embodiment have a compressive strength of 0.6 MPa. Under specific conditions of irradiation with simulated sunlight for 2 hours, they can degrade 76.0% of tetracycline hydrochloride (100 mg / L) and 90.1% of methyl orange (100 mg / L).

[0077] Example 6

[0078] The preparation process of basic magnesium sulfate-Fe2O3 / SnO2 composite photocatalytic material is as follows:

[0079] (1) Mix 5 parts of powdered Fe2O3, 5 parts of powdered SnO2, 2 parts of succinic acid, 15 parts of magnesium sulfate, and 73 parts of water, and stir thoroughly to make a uniform slurry.

[0080] (2) Mix 90 parts of active magnesium oxide and 10 parts of powdered basic magnesium sulfate 5·1·7 (5Mg(OH)2·MgSO4·7H2O) and stir thoroughly to make a uniform mixed powder.

[0081] (3) Add 30 parts of the mixed powder and 2 parts of 30% hydrogen peroxide to 68 parts of the mixed slurry, stir thoroughly and mix quickly until uniform, then dispense into 4cm containers. 2 The reaction was carried out in a 0.5cm mold to obtain a basic magnesium sulfate-Fe2O3 / SnO2 composite sheet.

[0082] Tests showed that the basic magnesium sulfate-Fe2O3 / SnO2 composite sheet obtained in this embodiment has a compressive strength of 0.6 MPa. Under specific conditions of irradiation for 2 hours under a light source of 280-600 nm, it can degrade 65.9% of tetracycline hydrochloride (100 mg / L) and 80.3% of methyl orange (100 mg / L).

[0083] Example 7

[0084] The preparation process of basic magnesium sulfate-FeO / NiO composite photocatalytic material is as follows:

[0085] (1) Mix 2 parts of powdered FeO, 8 parts of powdered NiO, 5 parts of gluconic acid, 10 parts of magnesium sulfate, and 75 parts of water, and stir thoroughly to make a uniform slurry.

[0086] (2) Mix 95 parts of active magnesium oxide and 5 parts of powdered basic magnesium sulfate 5·1·7 (5Mg(OH)2·MgSO4·7H2O) and stir thoroughly to make a uniform mixed powder.

[0087] (3) Add 40 parts of the mixed powder and 2 parts of calcium stearate to 58 parts of the mixed slurry, stir thoroughly and mix quickly until uniform, then dispense into 2cm containers. 2 The reaction is shaped in a 0.5cm mold to obtain a basic magnesium sulfate-FeO / NiO composite sheet.

[0088] Tests showed that the basic magnesium sulfate-FeO / NiO composite sheet obtained in this embodiment has a compressive strength of 0.7 MPa. Under specific conditions of irradiation for 2 hours under a light source of 280-600 nm, it can degrade 59.3% of tetracycline hydrochloride (100 mg / L) and 55.0% of methyl orange (100 mg / L).

[0089] Example 8

[0090] The preparation process of basic magnesium sulfate-MnO / NiO composite photocatalytic material is as follows:

[0091] (1) Mix 5 parts powdered MnO, 5 parts powdered NiO, 5 parts lactic acid with 18 parts magnesium sulfate and 67 parts water, stir thoroughly to make a uniform slurry;

[0092] (2) Mix 93 parts of active magnesium oxide and 7 parts of powdered basic magnesium sulfate 5·1·7 (5Mg(OH)2·MgSO4·7H2O) and stir thoroughly to make a uniform mixed powder.

[0093] (3) Add 42 parts of the mixed powder and 3 parts of polyvinyl alcohol to 55 parts of the mixed slurry, stir thoroughly and mix quickly until uniform, then dispense into 2cm containers. 2 The reaction is shaped in a 0.5cm mold to obtain basic magnesium sulfate-MnO / NiO composite sheet.

[0094] Tests showed that the basic magnesium sulfate-MnO / NiO composite sheet obtained in this embodiment has a compressive strength of 0.8 MPa. Under specific conditions of irradiation for 2 hours under a light source of 280-600 nm, it can degrade 82.0% of tetracycline hydrochloride (100 mg / L) and 87.4% of methyl orange (100 mg / L).

[0095] Example 9

[0096] The preparation process of basic magnesium sulfate-CoO composite photocatalytic material is as follows:

[0097] (1) Mix 20 parts of powdered CoO, 5 parts of maleic acid, 15 parts of magnesium sulfate, and 60 parts of water, and stir thoroughly to make a uniform slurry.

[0098] (2) Mix 85 parts of active magnesium oxide and 15 parts of powdered basic magnesium sulfate 5·1·7 (5Mg(OH)2·MgSO4·7H2O) and stir thoroughly to make a uniform mixed powder.

[0099] (3) Add 25 parts of mixed powder and 3 parts of lauroyl glutamic acid to 72 parts of mixed slurry, stir thoroughly and mix quickly and evenly, then package into 2cm×2cm×2cm molds for reaction molding, grind and pass through 5-60 mesh sieves to obtain basic magnesium sulfate-CoO composite particles.

[0100] Tests showed that the basic magnesium sulfate-CoO composite particles obtained in this embodiment have a compressive strength of 0.5 MPa. Under specific conditions of irradiation for 2 hours under a light source of 280-600 nm, they can degrade 55.9% of tetracycline hydrochloride (100 mg / L) and 70.3% of methyl orange (100 mg / L).

[0101] Example 10

[0102] The preparation process of basic magnesium sulfate-CoO / CeO2 composite photocatalytic material is as follows:

[0103] (1) Mix 10 parts CoO, 10 parts powdered CeO2, 5 parts glucohepatic acid with 25 parts magnesium sulfate and 50 parts water, stir thoroughly, and make a uniform slurry.

[0104] (2) Mix 90 parts of active magnesium oxide and 10 parts of powdered basic magnesium sulfate 5·1·7 (5Mg(OH)2·MgSO4·7H2O) and stir thoroughly to make a uniform mixed powder.

[0105] (3) Add 30 parts of mixed powder and 2 parts of sodium octadecyl sulfate to 78 parts of mixed slurry, stir thoroughly and mix quickly and evenly, then package into 2cm×2cm×2cm molds for reaction molding, grind and pass through 5-60 mesh sieves to obtain basic magnesium sulfate-CoO / CeO2 composite particles.

[0106] Tests showed that the basic magnesium sulfate-CoO / CeO2 composite particles obtained in this embodiment have a compressive strength of 0.5 MPa. Under specific conditions of irradiation for 2 hours under a light source of 280-600 nm, they can degrade 86.5% of tetracycline hydrochloride (100 mg / L) and 91.2% of methyl orange (100 mg / L).

[0107] Compare with Example 1

[0108] This comparative example is basically the same as Example 1, except that formic acid was not added in step (1). However, the material is difficult to mold and turns into powder in water.

[0109] Compare with Example 2

[0110] This comparative example is basically the same as Example 1, except that powdered basic magnesium sulfate was not added in step (2).

[0111] Tests showed that the compressive strength of the composite photocatalytic material obtained in this embodiment was 0.2 MPa. Under specific conditions of irradiation for 2 hours under a light source of 280-600 nm, it could degrade 40.5% of tetracycline hydrochloride (100 mg / L) and 51.2% of methyl orange (100 mg / L).

[0112] Compare with Example 3

[0113] This comparative example is basically the same as Example 1, except that active magnesium oxide was not added in step (2). However, the material could not be formed.

[0114] Compare with Example 4

[0115] This comparative example is basically the same as Example 1, except that hydrogen peroxide was not added in step (3).

[0116] Tests showed that the compressive strength of the composite photocatalytic material obtained in this embodiment was 0.9 MPa. Under specific conditions of irradiation for 2 hours under a light source of 280-600 nm, it could degrade 25.7% of tetracycline hydrochloride (100 mg / L) and 31.5% of methyl orange (100 mg / L).

[0117] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0118] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the described embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims.

Claims

1. A composite photocatalytic material, characterized in that, The product comprises the following components by mass: 50-98 parts basic magnesium sulfate and 2-50 parts photocatalyst, wherein the basic magnesium sulfate is an irregular cementitious body of 5Mg(OH)2·MgSO4·7H2O, and the photocatalyst is selected from any one or a combination of two or more of TiO2, ZnO, CuO, SnO2, FeO, Fe2O3, MnO, CoO, NiO, Bi2O3, WO3, and CeO2. The composite photocatalytic material was prepared by the following method: A photocatalyst, an organic weak acid, and a magnesium sulfate aqueous solution are uniformly mixed to prepare a mixed slurry. Active magnesium oxide and a nucleating agent are uniformly mixed to form a mixed powder; the nucleating agent is basic magnesium sulfate, which is an irregular cementitious body of 5Mg(OH)2·MgSO4·7H2O; The mixed powder, pore-forming agent, and mixed slurry are mixed evenly, and then reacted and shaped to obtain the composite photocatalytic material; the pore-forming agent is selected from any one or a combination of two or more of hydrogen peroxide, surfactant, and protein solution; the surfactant is selected from any one or a combination of two or more of sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium lignosulfonate, calcium stearate, polyvinyl alcohol, lauroyl glutamic acid, sodium octadecyl sulfate, and hexadecyltrimethylammonium bromide.

2. The composite photocatalytic material according to claim 1, characterized in that: The mechanical strength of the composite photocatalytic material is above 0.4 MPa.

3. The composite photocatalytic material according to claim 2, characterized in that: The mechanical strength of the composite photocatalytic material is 0.4~1 MPa.

4. A method for preparing the composite photocatalytic material according to any one of claims 1-3, characterized in that, include: A photocatalyst, an organic weak acid, and a magnesium sulfate aqueous solution are uniformly mixed to prepare a mixed slurry. Active magnesium oxide and a nucleating agent are uniformly mixed to form a mixed powder; the nucleating agent is basic magnesium sulfate, which is an irregular cementitious body of 5Mg(OH)2·MgSO4·7H2O; The mixed powder, pore-forming agent, and mixed slurry are mixed evenly, and then reacted and shaped to obtain the composite photocatalytic material. The pore-forming agent is selected from any one or a combination of two or more of hydrogen peroxide, surfactant, and protein solution; the surfactant is selected from any one or a combination of two or more of sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium lignosulfonate, calcium stearate, polyvinyl alcohol, lauroyl glutamic acid, sodium octadecyl sulfate, and hexadecyltrimethylammonium bromide.

5. The preparation method according to claim 4, characterized in that: The photocatalyst is selected from any one or a combination of two or more of TiO2, ZnO, CuO, SnO2, FeO, Fe2O3, MnO, CoO, NiO, Bi2O3, WO3, and CeO2.

6. The preparation method according to claim 4, characterized in that: said organic weak acid is selected from any one or a combination of two of R(COOH) n , HOR(COOH) n wherein R is a hydrocarbon group and n is an integer greater than or equal to 1.

7. The preparation method according to claim 6, characterized in that: The organic weak acid is selected from any one or a combination of two or more of the following: formic acid, itaconic acid, malic acid, tannic acid, salicylic acid, succinic acid, gluconic acid, lactic acid, maleic acid, and glucoheponic acid.

8. The preparation method according to claim 4, characterized in that, include: Magnesium sulfate is mixed with water to prepare the magnesium sulfate aqueous solution.

9. The preparation method according to claim 8, characterized in that, The mixed slurry comprises the following components by mass: 0.5-5 parts of organic weak acid, 5-25 parts of magnesium sulfate, 5-20 parts of photocatalyst, and 50-89.5 parts of water.

10. The preparation method according to claim 4, characterized in that: The mass ratio of the nucleating agent to active magnesium oxide is 5~15:85~95.

11. The preparation method according to claim 4, characterized in that: The mass ratio of the mixed powder, pore-forming agent and mixed slurry is (20~50):(0.5~5):(45~79.5).

12. The preparation method according to claim 4, characterized in that: The reaction is carried out at room temperature for more than 24 hours and aged for more than 2 days.