Advanced oxidation catalyst as well as preparation method and application thereof

Abstract

The invention discloses an advanced oxidation catalyst as well as a preparation method and application thereof, and relates to the technical field of water treatment. The inert middle protective layer is coated on the outer surface of the magnetic inner core; the metal oxygen halide catalytic active layer is arranged outside the inert middle protective layer; the functional group layer is modified on the outer surface of the metal oxygen halide catalytic active layer; wherein the functional group layer comprises a hydrophilic functional group and a hydrophobic-electropositive functional group. The advanced oxidation catalyst adopts a unique four-layer composite design, and a synergistic modification layer containing a hydrophilic functional group and a hydrophobic-electropositive functional group is constructed on the surface of the advanced oxidation catalyst, so that the catalyst is particularly suitable for a seawater environment, can selectively enrich hydrogen peroxide and organic pollutants respectively, effectively inhibits interfering ions such as chlorine and bromine, and has a good application prospect. Therefore, efficient removal of organic pollutants is realized under the condition of low hydrogen peroxide dosage, and generation of halogenated disinfection by-products is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and more specifically, to an advanced oxidation catalyst, its preparation method, and its application. Background Technology

[0002] With the development of industry and agriculture, various organic pollutants enter the ocean through aquaculture or land-based sources, damaging the marine ecological environment and threatening human health. Advanced oxidation processes (AOPs) utilize catalysts and oxidants to oxidize organic pollutants in water, achieving highly efficient removal and are a widely used water treatment method. Various oxidants, including hydrogen peroxide, are applied to the AOP treatment of various organic pollutants in water. However, inorganic ions such as chloride ions in water interfere with the AOP process, consuming reactive oxygen species formed during AOP, resulting in hydrogen peroxide waste and inhibiting pollutant removal. To ensure high pollutant removal rates, the dosage of hydrogen peroxide needs to be increased, leading to higher treatment costs. The problem is even more severe when the treated water medium is seawater. Seawater has a chloride ion content more than two orders of magnitude higher than freshwater and contains a higher concentration of bromide ions, not only wasting hydrogen peroxide but also leading to the formation of various halogenated disinfection byproducts after the AOP reaction.

[0003] In recent years, the contribution of oxidative polymerization to advanced oxidation processes (AOPs) has attracted considerable attention. Some organic pollutants, such as phenols, halogenated phenols, aromatic amines, or sulfonamide antibiotics, can be polymerized during AOPs, thus enabling their removal from the aqueous phase. Compared to classical degradation and mineralization pathways, oxidative polymerization purifies water through pollutant polymerization, reducing hydrogen peroxide consumption. Through catalyst structure design, AOP pathways can be directionally controlled, increasing the proportion of oxidative polymerization and reducing hydrogen peroxide consumption. However, when existing catalysts are applied to the oxidative polymerization removal of organic pollutants in seawater, the problem of interference from high concentrations of chloride and bromide ions remains unresolved. Summary of the Invention

[0004] The purpose of this invention is to overcome the aforementioned deficiencies in the prior art and provide an advanced oxidation catalyst, its preparation method, and its application. The advanced oxidation catalyst of this invention employs a unique four-layer composite design: a magnetic core enables convenient magnetic separation and recovery; an inert intermediate protective layer effectively isolates the magnetic core, preventing corrosion and avoiding its participation in the reaction, thus shifting the advanced oxidation reaction pathway towards a degradation and mineralization pathway; the metal oxyhalide can be selected from catalytic materials such as bismuth iodide, bismuth bromooxy, bismuth chloride, bismuth fluoride, iron chloride, or vanadium chloride to promote the shift of the advanced oxidation reaction towards an oxidative polymerization pathway, thereby effectively removing organic pollutants through oxidative polymerization at low hydrogen peroxide dosages. Most importantly, its surface is constructed with a synergistic modification layer including hydrophilic and hydrophobic-positively charged functional groups, wherein the hydrophobic-positively charged functional groups simultaneously contain quaternary ammonium cations and C8-C30 alkyl chains, making the catalyst particularly suitable for seawater environments. It can selectively enrich hydrogen peroxide and organic pollutants, and effectively suppress interfering ions such as chlorine and bromine, thereby achieving highly efficient removal of organic pollutants at low hydrogen peroxide dosages and significantly reducing the formation of halogenated disinfection byproducts. The key innovation of this invention lies in using a magnetic core as the core, which is then coated with an inert intermediate protective layer and a metal oxyhalide catalytic active layer. The surface of the core is then synergistically modified to form a modified layer containing hydrophilic and hydrophobic-positive functional groups. This allows the catalyst to effectively suppress interference from chlorine and bromine ions in a seawater environment, thus exhibiting superior performance beyond conventional methods.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: An advanced oxidation catalyst, the catalyst comprising: a magnetic core; an inert intermediate protective layer covering the outer surface of the magnetic core; a metal oxyhalide catalytic active layer disposed outside the inert intermediate protective layer; and a functional group layer modified on the outer surface of the metal oxyhalide catalytic active layer; wherein the functional group layer comprises hydrophilic functional groups and hydrophobic-positively charged functional groups.

[0006] This invention also discloses a method for preparing the advanced oxidation catalyst as described above, comprising the following steps: S1. Prepare magnetic particles as magnetic cores; S2. An inert intermediate protective layer is coated onto the magnetic core to obtain composite structure one; S3. A metal oxide halide catalytic active layer is grown in situ on the surface of the first composite structure to obtain the second composite structure. S4. The surface of the composite structure II is modified by sequentially introducing hydrophilic functional groups and hydrophobic-positively charged functional groups to form a functional group layer, thereby obtaining the advanced oxidation catalyst.

[0007] The present invention also discloses the application of the advanced oxidation catalyst as described above, or the advanced oxidation catalyst prepared by the preparation method described above, in the advanced oxidation removal of organic pollutants in seawater.

[0008] Implementing the embodiments of the present invention will have the following beneficial effects: (1) The magnetic core in the advanced oxidation catalyst provided by the present invention endows the catalyst with magnetic separation characteristics, and the catalyst can be conveniently separated from the treated water by an external magnetic field after the reaction.

[0009] (2) The inert intermediate protective layer in the advanced oxidation catalyst provided by the present invention isolates the magnetic core inside, which has two functions: on the one hand, it prevents the magnetic core from being corroded, so that the magnetic separation characteristics of the catalyst can be maintained; on the other hand, the iron, cobalt, nickel and their oxides in the magnetic core are common catalysts for advanced oxidation reactions, which will cause the advanced oxidation reaction pathway to shift to the degradation and mineralization pathway. The inert protective intermediate layer isolates them inside, prevents them from participating in the reaction, and reduces the contribution of the degradation and mineralization pathway to the removal of organic pollutants.

[0010] (3) The metal oxyhalide catalytic active layer in the advanced oxidation catalyst provided by the present invention can promote the advanced oxidation reaction to shift to the oxidative polymerization pathway, thereby effectively removing organic pollutants through oxidative polymerization with low hydrogen peroxide dosage and reducing the amount of hydrogen peroxide added.

[0011] (4) The advanced oxidation catalyst provided by this invention is simultaneously modified with hydrophilic functional groups and hydrophobic-positively charged functional groups on its surface, which can effectively suppress the interference effects of chloride ions and bromide ions: First, the hydrophobic-positively charged functional group is composed of C8-C30 alkyl chains and quaternary ammonium cations. Seawater has a naturally alkaline pH. At this alkaline pH, easily polymerizable organic pollutants in seawater carry a negative charge and are attracted to the positively charged quaternary ammonium cations through electrostatic interactions. While chloride and bromide ions in seawater also carry a negative charge, their smaller ionic radii result in a more negative Gibbs free energy of hydration and stronger hydration compared to organic pollutants, thus suppressing the electrostatic interactions with the quaternary ammonium cations. Simultaneously, easily polymerizable organic pollutants are hydrophobic, and hydrophobic-hydrophobic interactions exist between them and the hydrophobic alkyl chains. Chloride and bromide ions are hydrophilic and have weak interactions with hydrophobic alkyl chains. Furthermore, easily polymerizable organic pollutants contain benzene rings, which have π electron clouds and can interact with positively charged quaternary ammonium cations via π-cation interactions. Chloride and bromide ions, on the other hand, lack π electron clouds and only have simple electrostatic attraction with quaternary ammonium cations. In addition, easily polymerizable organic pollutant ions have larger ionic radii, and because electrostatic forces are not saturated, they can interact with multiple positive potential points on the surface. As a result of the combined effect of these factors, hydrophobic-positively charged functional groups can selectively enrich easily polymerizable organic pollutants rather than interfering ions such as chloride and bromide ions.

[0012] Second, the hydrophilic functional group is hydrophilic and has a hydrophilic-hydrophilic interaction with hydrogen peroxide, which is also hydrophilic. However, under the natural alkaline pH of seawater, the hydrophilic functional group is negatively charged and has an electrostatic repulsion with chloride and bromide ions, which are also negatively charged. The hydrophilic functional group contains oxygen atoms and has a hydrogen bond with hydrogen peroxide, while there is no hydrogen bond between chloride and bromide ions and the hydrophilic functional group. As a result of the combined effect of multiple factors, the hydrophilic functional group can selectively enrich easily polymerizable hydrogen peroxide rather than interfering ions such as chloride and bromide ions.

[0013] Third, in heterogeneous advanced oxidation processes, hydrogen peroxide needs to be adsorbed on the catalyst surface and activated by the catalyst before it can participate in subsequent oxidation reactions. Since hydrogen peroxide is enriched on the hydrophilic functional groups on the catalyst surface, while easily polymerizable organic pollutants are enriched on the hydrophobic functional groups on the catalyst surface, the two are spatially closer and more likely to react. In contrast, chloride ions and bromide ions are dispersed in seawater and are far away from the hydrogen peroxide enriched on the catalyst surface, and cannot directly react with the unadsorbed hydrogen peroxide in the water.

[0014] In summary, when the catalyst of this invention is applied to the removal of easily polymerizable organic pollutants in seawater, it can effectively suppress the interference of chloride and bromide ions, efficiently remove organic pollutants with low hydrogen peroxide dosage, and reduce the generation of halogenated disinfection byproducts. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the advanced oxidation catalyst of the present invention. Detailed Implementation

[0016] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0017] This invention discloses an advanced oxidation catalyst, comprising: a magnetic core; an inert intermediate protective layer covering the outer surface of the magnetic core; a metal oxyhalide catalytic active layer disposed outside the inert intermediate protective layer; and a functional group layer modified on the outer surface of the metal oxyhalide catalytic active layer; wherein the functional group layer comprises hydrophilic functional groups and hydrophobic-positively charged functional groups.

[0018] In one specific embodiment, the hydrophobic-positive functional group includes a quaternary ammonium cation and a C8-C30 alkyl chain directly bonded thereto.

[0019] In one specific embodiment, the hydrophilic functional group is selected from at least one of sulfonic acid group, carboxyl group, phosphonic acid group, hydroxyl group, amino group and polyethylene glycol chain.

[0020] In one specific embodiment, the hydrophobic-positive functional group is introduced through a functionalized molecule having the general formula (I): (R 1 O) 3-a (R 2 ) a Si — R 3 — N + (R 4 (R) 5 )R 6 · X - (General Formula I) Among them, R 1 Independently C1-C4 alkyl; R 2 Independently C1-C4 alkyl; a is 0, 1, or 2; R 3 It is a C1-C12 alkylene linkage; R 4 and R 5 Independently a C1-C4 alkyl group; R 6 The hydrophobic portion is composed of a C8-C30 straight-chain or branched alkyl group; X - To counteract anions.

[0021] In one specific embodiment, the counter anion is selected from Cl. - ,Br - I - At least one of them.

[0022] In one specific embodiment, the functionalized molecule is at least one of dimethyloctadecyl[tri-(trimethoxysilyl)propyl]ammonium chloride and dimethyldodecyl[tri-(trimethoxysilyl)propyl]ammonium chloride.

[0023] In one specific embodiment, the magnetic core is selected from at least one of an iron core, a cobalt core, a nickel core, a magnetite core, a cobalt ferrite core, and a nickel ferrite core.

[0024] In one specific embodiment, the inert intermediate protective layer is selected from at least one of the following: silicon dioxide protective layer, aluminum oxide protective layer, zirconium dioxide protective layer, amorphous carbon protective layer, and polydopamine protective layer.

[0025] In one specific embodiment, the material of the metal oxyhalide catalytic active layer is selected from at least one of bismuth oxyiodide layer, bismuth oxybromide layer, bismuth oxychloride layer, bismuth oxyfluoride layer, iron oxychloride layer, and vanadium oxychloride layer.

[0026] In one specific embodiment, based on the total mass of the catalyst, the mass percentage of each component is as follows: 10%~50% magnetic core, 5%~30% inert intermediate protective layer, 20%~60% metal oxyhalide catalytic active layer and 1%~10% functional group layer.

[0027] Specifically, the magnetic core in the catalyst endows it with magnetic separation properties, allowing it to be easily separated from the treated water after the reaction by an external magnetic field. An inert intermediate protective layer isolates the magnetic core, preventing corrosion and avoiding its participation in the reaction, thus preventing the advanced oxidation pathway from shifting towards degradation and mineralization. The metal oxyhalide catalytic active layer promotes the shift of the advanced oxidation reaction towards oxidative polymerization, effectively removing organic pollutants through oxidative polymerization even with low hydrogen peroxide dosage. The surface-modified hydrophobic-positively charged functional groups selectively enrich readily polymerizable organic pollutants instead of interfering ions such as chloride and bromide ions, while the surface hydrophilic functional groups selectively enrich hydrogen peroxide instead of interfering ions such as chloride and bromide ions, effectively suppressing the interference of chloride and bromide ions on the advanced oxidation reaction. Therefore, the catalyst provided by this invention, with its multiple components working synergistically, effectively solves the problems of high hydrogen peroxide dosage and excessive halogenated disinfection byproducts when applied to the removal of organic pollutants from seawater in existing technologies.

[0028] This invention also discloses a method for preparing the advanced oxidation catalyst as described above, comprising the following steps: S1. Prepare magnetic particles as magnetic cores.

[0029] In one specific embodiment, there is no particular limitation on the preparation method of the magnetic core in step S1. Any synthesis method known to those skilled in the art can be used, including but not limited to co-precipitation method, solvothermal method or high-temperature calcination method.

[0030] In one specific embodiment, when using the co-precipitation method, the preparation temperature is 50°C and the preparation time is 1 hour.

[0031] In one specific embodiment, taking the iron oxide core as an example, it is prepared by coprecipitation method: ferric chloride hexahydrate and ferric chloride tetrahydrate are dissolved in deionized water, and ammonia is added dropwise under nitrogen protection and mechanical stirring. The reaction is carried out at 50°C for 1 hour. The product is separated by a magnet and washed with water and ethanol until neutral. It is then dried under vacuum at 60°C to obtain the iron oxide core.

[0032] S2. An inert intermediate protective layer is coated on the magnetic core to obtain composite structure one.

[0033] In one specific embodiment, the coating method includes the sol-gel method, precipitation method, or solvothermal method.

[0034] In one specific embodiment, the coating temperature is 40~80℃; the coating time is 6~18h.

[0035] In one specific embodiment, taking the silica protective layer as an example, the preparation method includes: dispersing the magnetic core in a mixture of ethanol and water by ultrasonic dispersion; then adding ammonia water and slowly adding tetraethyl orthosilicate, reacting at 40°C for 6 hours; and then sequentially performing magnetic separation, washing and drying to obtain composite structure one.

[0036] S3. A metal oxyhalide catalytic active layer is grown in situ on the surface of composite structure one to obtain composite structure two.

[0037] In one specific embodiment, the in-situ growth method includes the sol-gel method, the solvothermal method, or the coprecipitation method.

[0038] In one specific embodiment, the in-situ growth temperature is 120~200℃; the in-situ growth time is 8~48h.

[0039] In one specific embodiment, taking the bismuth oxychloride layer as an example, the preparation method includes: dispersing composite structure one in ethylene glycol to obtain a dispersion; dissolving bismuth nitrate pentahydrate in ethylene glycol and adding it to the above dispersion; subsequently, dissolving potassium chloride in ethylene glycol and slowly adding it dropwise to the reaction system; transferring the mixture to a high-pressure reactor and reacting at 160°C for 12 hours; after the reaction, cooling, magnetic separation, ethanol washing, and drying at 60°C are performed sequentially to obtain composite structure two.

[0040] S4. The surface of composite structure II is modified by sequentially introducing hydrophilic functional groups and hydrophobic-positive functional groups to form a functional group layer, thereby obtaining an advanced oxidation catalyst.

[0041] In one specific embodiment, step S4 includes: By modifying the surface of composite structure 2 with hydrophilic properties and introducing hydrophilic functional groups, composite structure 3 was obtained. By modifying the surface of the composite structure III with hydrophobic-positive charge to introduce hydrophobic-positive charge functional groups, an advanced oxidation catalyst was obtained.

[0042] It should be understood that the hydrophilic functional group can be constructed in the following ways: First, by directly introducing a hydrophilic modifier, which is a silane compound with the target hydrophilic functional group (such as sulfonic acid group, carboxyl group, amino group, hydroxyl group, polyethylene glycol chain, etc.), which is bonded to the catalyst surface through a silanization reaction; Second, by first introducing an easily convertible group (such as a mercapto group) and then converting it into the target hydrophilic functional group (such as a sulfonic acid group) through subsequent oxidation or other reactions. Based on the above mechanism, the hydrophilic surface modification of the present invention preferably uses a modifier that can form a strong covalent bond with the catalyst surface through a silanization reaction.

[0043] In one specific embodiment, the hydrophilic surface modification includes the following steps: dispersing composite structure II in a solvent, adding a hydrophilic modifier, and refluxing at 60-100°C for 8-24 hours under nitrogen protection; then magnetically separating and washing with toluene and ethanol; redispersing the product in a mixture of hydrogen peroxide and nitric acid, and stirring at 50-90°C for 4-12 hours; then magnetically separating, and washing and drying with water to obtain composite structure III.

[0044] In one specific embodiment, the solvent used for hydrophilic surface modification is anhydrous toluene.

[0045] In one specific embodiment, the mass-to-volume ratio of composite structure II, hydrophilic modifier, and mixture is 100 mg: 0.05~0.2 mL: 30~60 mL.

[0046] In one specific embodiment, the concentration of hydrogen peroxide in the mixture is 20-40%, and the concentration of nitric acid is 0.5-2M.

[0047] In one specific embodiment, the hydrophobic-positive surface modification includes the following steps: the composite structure is triply dispersed in a solvent, a hydrophobic-positive modifier is added, and the mixture is refluxed at 60-100°C for 8-24 hours under nitrogen protection; then magnetic separation is performed, followed by washing with toluene and ethanol, and then vacuum drying at 40-80°C to obtain an advanced oxidation catalyst.

[0048] In one specific embodiment, the solvent used for hydrophobic-positive surface modification is anhydrous toluene.

[0049] In one specific embodiment, the mass-to-volume ratio of the composite structure and the hydrophobic-positively charged modifier is 100 mg: 0.1~0.3 mL.

[0050] In one specific embodiment, the hydrophilic surface modification uses a hydrophilic modifier comprising at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-(trihydroxysilyl)-propanesulfonic acid, 3-(trimethoxysilyl)propionic acid, 4-(trimethoxysilyl)butyric acid, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-hydroxypropyltrimethoxysilane, and methoxypolyethylene glycol propyltrimethoxysilane.

[0051] In one specific embodiment, the hydrophobic-positive surface modification uses at least one of dimethyloctadecyl[tri-(trimethoxysilyl)propyl]ammonium chloride and dimethyldodecyl[tri-(trimethoxysilyl)propyl]ammonium chloride.

[0052] The present invention also discloses the application of the advanced oxidation catalyst as described above, or the advanced oxidation catalyst prepared by the preparation method described above, in the advanced oxidation removal of organic pollutants in seawater.

[0053] In one specific embodiment, the organic pollutant is an organic pollutant that is prone to polymerization.

[0054] In one specific embodiment, readily polymerizable organic pollutants refer to organic compounds whose molecular structures have active sites that readily couple to form dimers or higher molecular weight polymers during advanced oxidation processes.

[0055] In one specific embodiment, the easily polymerizable organic pollutant is at least one of phenols, halogenated phenols, aromatic amines, and sulfonamide antibiotics.

[0056] In one specific embodiment, the easily polymerizable organic pollutant is at least one of phenol, bisphenol A, 2,4-dichlorophenol, aniline, and sulfamethoxazole.

[0057] In one specific embodiment, the application method includes: adding an advanced oxidation catalyst and hydrogen peroxide to seawater containing readily polymerizable organic pollutants, and carrying out an advanced oxidation reaction under stirring or ultrasonic conditions.

[0058] In one specific embodiment, the temperature of the advanced oxidation reaction is 20°C to 40°C; the pressure of the advanced oxidation reaction is atmospheric pressure.

[0059] In one specific embodiment, the concentration of easily polymerizable organic pollutants in seawater is 1 mg / L to 1000 mg / L, the dosage of advanced oxidation catalyst is 0.05 g / L to 1 g / L, and the dosage of hydrogen peroxide is 0.005 g / L to 0.5 g / L.

[0060] In one specific embodiment, the pH of the seawater is 7.5 to 8.5.

[0061] In one specific embodiment, the reaction time is 5 min to 6 h.

[0062] Specifically, the advanced oxidation catalyst used in this invention can effectively suppress the interference of chloride and bromide ions under seawater conditions, reduce the amount of hydrogen peroxide added, and reduce the generation of halogenated disinfection byproducts, exhibiting excellent catalytic performance.

[0063] The following are specific embodiments. Example 1 1. Preparation of magnetite (Fe3O4) magnetic cores: A co-precipitation method was used. 5.2 g of ferric chloride hexahydrate and 2.0 g of ferric chloride tetrahydrate were dissolved in 100 mL of deionized water. Under nitrogen protection and mechanical stirring, 10 mL of ammonia (28%) was added dropwise, and the reaction was carried out at 50 °C for 1 h. The product was separated using a magnet, washed with water and ethanol until neutral, and dried under vacuum at 60 °C to obtain magnetite magnetic particles.

[0064] 2. Coating with a silica intermediate protective layer: 100 mg of the above-mentioned ferric oxide was dispersed in a mixture of 80 mL ethanol and 20 mL water and ultrasonically dispersed. 2 mL of ammonia water was added, followed by slow dropwise addition of 0.5 mL of tetraethyl orthosilicate. The mixture was reacted at 40 °C for 6 h. After magnetic separation, washing, and drying, ferric oxide@silica was obtained.

[0065] 3. In-situ growth of the bismuth oxychloride catalytic active layer: 100 mg of iron(III) oxide@silica was dispersed in 40 mL of ethylene glycol. Separately, 2.4 g of bismuth nitrate pentahydrate was dissolved in 20 mL of ethylene glycol and added to the dispersion. Subsequently, 0.6 g of potassium chloride was dissolved in 10 mL of ethylene glycol and slowly added dropwise to the reaction system. The mixture was transferred to a 100 mL high-pressure reactor and reacted at 160 °C for 12 h. After cooling, magnetic separation was performed, followed by washing with ethanol and drying at 60 °C to obtain iron(III) oxide@silica@bismuth oxychloride.

[0066] 4. Hydrophilic Surface Modification: 100 mg of iron(II) oxide@silica@bismuth oxychloride was dispersed in 50 mL of anhydrous toluene, and 0.1 mL of 3-mercaptopropyltrimethoxysilane was added. The mixture was refluxed at 80 °C for 12 h under nitrogen protection. Magnetic separation was performed, followed by washing with toluene and ethanol. The product was redispersed in a mixture of 30 mL of 30% hydrogen peroxide and 20 mL of 1 M nitric acid, and stirred at 60 °C for 6 h to oxidize the mercapto groups to sulfonic acid groups. Magnetic separation was performed, and the mixture was thoroughly washed with water to remove hydrogen peroxide and other residual substances to avoid interference with subsequent preparation steps and performance testing. The product was dried to obtain iron(II) oxide@silica@bismuth oxychloride-sulfonic acid group.

[0067] 5. Hydrophobic-Positive Surface Modification: 100 mg of iron(II) oxide@silicon dioxide@bismuth oxychloride-sulfonic acid group was dispersed in 50 mL of anhydrous toluene, and 0.15 mL of dimethyloctadecyl[tris-(trimethoxysilyl)propyl]ammonium chloride (CAS No.: 27668-52-6) was added. The mixture was refluxed at 80 °C for 24 h under nitrogen protection. After magnetic separation, the mixture was washed with toluene and ethanol, and dried under vacuum at 60 °C to obtain advanced oxidation catalyst 1, named Cat-1.

[0068] Example 2: The only difference between this embodiment and Embodiment 1 is that: In step 3, sodium bromide is used instead of potassium chloride to prepare the catalytic active layer of iron tetroxide@silicon dioxide@bismuth oxybromide.

[0069] In step 5, dimethyldodecyl[tri-(trimethoxysilyl)propyl]ammonium chloride (CAS No.: 27668-53-7) was used as a hydrophobic-positive modifier.

[0070] The advanced oxidation catalyst of this embodiment was prepared according to the preparation method of Example 1 and named Cat-2.

[0071] Comparative Example 1 The only difference between this comparative example and Example 1 is that the preparation of the intermediate protective layer of silicon dioxide in step 2 is omitted. After obtaining the magnetic core of iron oxide according to the preparation method in step 1 of Example 1, the in-situ growth of the bismuth oxychloride catalytic active layer of iron oxide@bismuth oxychloride is prepared according to the method in step 3 of Example 1. The remaining steps are the same as in Example 1 to obtain catalyst Comp-1.

[0072] Comparative Example 2 The only difference between this comparative example and Example 1 is that the surface modification steps 4 and 5 are omitted.

[0073] The catalyst Comp-2 was prepared by following steps 1-3 in Example 1 to obtain the catalyst Fe3O4@Silicon Dioxide@Bismuth Oxide.

[0074] Comparative Example 3 The only difference between this comparative example and Example 1 is that the hydrophobic-positive surface modification step 5 is omitted.

[0075] The catalyst Comp-3 was prepared by following steps 1-4 in Example 1, which yielded a mixture of iron(II) oxide, silicon dioxide, and bismuth oxychloride-sulfonic acid.

[0076] Comparative Example 4 The only difference between this comparative example and Example 1 is that the hydrophilic modification step in step 4 is omitted. Following steps 1-3 and 5 of Example 1, Fe3O4@Silica@Bismuthoxychloride-quaternary ammonium salt / C18 was prepared to obtain catalyst Comp-4.

[0077] Comparative Example 5 The only difference between this comparative example and Example 1 is that the modifier used in step 5 is octadecyltrimethoxysilane (without quaternary ammonium salt) for hydrophobic modification.

[0078] The catalyst Comp-5 was prepared by following steps 1-5 in Example 1 to obtain the catalyst ferric oxide@silicon dioxide@bismuth oxychloride-sulfonic acid-C18.

[0079] Advanced oxidation performance test experiment The removal performance of various catalysts for bisphenol A (10 mg / L) was evaluated in simulated seawater (salinity 3.5%, pH=8.0). Catalyst (0.2 g / L) and hydrogen peroxide (0.01 g / L) were added to 100 mL of simulated seawater containing bisphenol A. After reacting at 25℃ for 2 h, samples were taken, and the residual concentration of bisphenol A in the water was determined after magnetic separation. The total organic halogen (TOX) formation in the reaction solution was also measured. The results are shown in the table below: Table 1

[0080] Comparing the bisphenol A removal rate and total organic halogen formation in the seawater treatment examples with the comparative examples demonstrates the necessity of magnetic core protection and surface modification. The precise surface modification synergistic system, composed of hydrophilic regions, hydrophobic alkyl chains, and quaternary ammonium salt positively charged centers, effectively improves pollutant removal rates and reduces the formation of disinfection byproducts even with low hydrogen peroxide dosage.

[0081] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An advanced oxidation catalyst, characterized in that, The catalyst includes: Magnetic core; An inert intermediate protective layer covering the outer surface of the magnetic core; A metal oxide halide catalytic active layer disposed outside the inert intermediate protective layer; and, A functional group layer modified on the outer surface of the metal oxyhalide catalytic active layer; wherein the functional group layer includes hydrophilic functional groups and hydrophobic-positively charged functional groups.

2. The advanced oxidation catalyst according to claim 1, characterized in that, The hydrophobic-positively charged functional group includes a quaternary ammonium cation and a C8-C30 alkyl chain directly bonded thereto; The hydrophilic functional group is selected from at least one of sulfonic acid group, carboxyl group, phosphonic acid group, hydroxyl group, amino group and polyethylene glycol chain.

3. The advanced oxidation catalyst according to claim 1, characterized in that, The hydrophobic-positive functional group is introduced through functionalized molecules having the general formula (I): (R 1 O) 3-a (R 2 ) a Si — R 3 — N + (R 4 )(R 5 )R 6 · X - (General formula I) Among them, R 1 Independently C1-C4 alkyl; R 2 Independently C1-C4 alkyl; a is 0, 1, or 2; R 3 It is a C1-C12 alkylene linkage; R 4 and R 5 Independently a C1-C4 alkyl group; R 6 It is an alkyl group of C8-C30; X - To counteract anions.

4. The advanced oxidation catalyst according to claim 1, characterized in that, The magnetic core is selected from at least one of iron core, cobalt core, nickel core, iron(II,III) oxide core, cobalt ferrite core and nickel ferrite core; The inert intermediate protective layer is selected from at least one of the following: silicon dioxide protective layer, aluminum oxide protective layer, zirconium dioxide protective layer, amorphous carbon protective layer, and polydopamine protective layer; The material of the metal oxyhalide catalytic active layer is selected from at least one of the following: bismuth oxyiodide layer, bismuth oxybromide layer, bismuth oxychloride layer, bismuth oxyfluoride layer, iron oxychloride layer, and vanadium oxychloride layer.

5. The advanced oxidation catalyst according to claim 1, characterized in that, Based on the total mass of the catalyst, the mass percentage of each component is as follows: 10%~50% magnetic core, 5%~30% inert intermediate protective layer, 20%~60% metal oxyhalide catalytic active layer and 1%~10% functional group layer.

6. A method for preparing an advanced oxidation catalyst as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Prepare magnetic particles as magnetic cores; S2. An inert intermediate protective layer is coated onto the magnetic core to obtain composite structure one; S3. A metal oxide halide catalytic active layer is grown in situ on the surface of the first composite structure to obtain the second composite structure. S4. The surface of the composite structure II is modified by sequentially introducing hydrophilic functional groups and hydrophobic-positively charged functional groups to form a functional group layer, thereby obtaining the advanced oxidation catalyst.

7. The preparation method according to claim 6, characterized in that, Step S4 includes: The second composite structure was modified with a hydrophilic surface to introduce hydrophilic functional groups, resulting in the third composite structure. The composite structure was modified with a hydrophobic-positive surface to introduce the hydrophobic-positive functional group, thus obtaining the advanced oxidation catalyst.

8. The preparation method according to claim 6, characterized in that, The hydrophilic surface modification includes the following steps: dispersing the second composite structure in a solvent, adding a hydrophilic modifier, and refluxing at 60-100°C for 8-24 hours under nitrogen protection; then magnetically separating and washing with toluene and ethanol; redispersing the product in a mixture of hydrogen peroxide and nitric acid, and stirring at 50-90°C for 4-12 hours; then magnetically separating, washing and drying with water to obtain the third composite structure; The hydrophobic-positive surface modification includes the following steps: the composite structure is triply dispersed in a solvent, a hydrophobic-positive modifier is added, and the mixture is refluxed at 60-100°C for 8-24 hours under nitrogen protection; then magnetic separation is performed, followed by washing with toluene and ethanol, and then vacuum drying at 40-80°C to obtain the advanced oxidation catalyst.

9. The preparation method according to claim 8, characterized in that, The mass-to-volume ratio of the second composite structure, the hydrophilic modifier, and the mixture is 100 mg: 0.05~0.2 mL: 30~60 mL; in the mixture, the concentration of hydrogen peroxide is 20~40%, and the concentration of nitric acid is 0.5~2 M. The mass-to-volume ratio of the composite structure 3 and the hydrophobic-positively charged modifier is 100 mg: 0.1~0.3 mL; The hydrophilic surface modification uses at least one of the following hydrophilic modifiers: 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-(trihydroxysilyl)-propanesulfonic acid, 3-(trimethoxysilyl)propionic acid, 4-(trimethoxysilyl)butyric acid, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-hydroxypropyltrimethoxysilane, and methoxypolyethylene glycol propyltrimethoxysilane. The hydrophobic-positive surface modification uses at least one of dimethyloctadecyl[tri-(trimethoxysilyl)propyl]ammonium chloride and dimethyldodecyl[tri-(trimethoxysilyl)propyl]ammonium chloride.

10. The application of an advanced oxidation catalyst as described in any one of claims 1-5, or an advanced oxidation catalyst prepared by any one of claims 6-9, in the advanced oxidation removal of organic pollutants in seawater.

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