Silver chloride / silver-copper ferrititanium oxide composite material and preparation method and application thereof

Abstract

This invention provides a method for preparing a silver chloride / silver-copper-iron-titanium oxide composite material, comprising the following steps: Step S1, citric acid is dissolved in an ethanol solution to obtain a mixture A; Step S2, tetrabutyl titanate solution is added dropwise to mixture A to obtain a mixture B; Step S3, copper nitrate and ferric nitrate are added to deionized water to obtain a mixture C; Step S4, mixture B is added dropwise to mixture C, and the pH is adjusted to obtain a mixture D; Step S5, mixture D undergoes a solvothermal reaction to obtain a precipitate; Step S6, the precipitate is washed, centrifuged, dried, and ground to obtain a copper-iron-titanium oxide material; Step S7, silver nitrate and the copper-iron-titanium oxide material are weighed and added to a quartz reaction tube, deionized water is added, and photodeposition is performed using a mercury lamp to obtain a mixed solution; Step S8, sodium chloride solution is added dropwise to the mixed solution to obtain a mixture; Step S9, the mixture is centrifuged, washed, dried, and ground to obtain a silver chloride-copper-iron-titanium oxide composite material.

Description

Technical Field

[0001] This invention belongs to the field of drinking water treatment technology, specifically relating to a silver chloride / silver-copper-iron-titanium oxide composite material, its preparation method, and its application. Background Technology

[0002] Nitrate (NO3) - Nitrate, a common non-metallic oxide found in water, possesses high solubility and fluidity, and is widely present in both natural and artificially treated water bodies worldwide. Groundwater, as an important source of drinking water, suffers from excessive nitrate levels in northern my country and some other regions. Excessive intake can lead to the conversion of nitrite into nitrite in the body, potentially causing hemoglobinemia and other diseases, seriously threatening human health. Advanced reduction technologies (ARPs), as a novel water treatment technology, utilize activated active groups to effectively reduce nitrate to substances such as ammonium and nitrogen. Increasing the nitrogen conversion rate can render the products harmless. Furthermore, heterogeneous photocatalytic treatment technology can reduce the amount of chemical reagents added, and magnetic materials offer advantages such as easy recycling and reduced secondary pollution, making these materials and technologies more practical.

[0003] Nitrate ions are characterized by their small molecular weight and stable properties. Currently, common methods for treating drinking water include physical, chemical, and biological methods (though biological treatment is less frequently used in drinking water treatment technology), such as reverse osmosis, ion exchange, adsorption, chemical reduction, and electrochemical reduction. Compared to these methods, which suffer from high energy consumption, high chemical dosage, stringent reaction conditions, and low removal rates, advanced reduction methods based on active groups have shown great promise as a novel technology in recent years. Research has found e aq - H · CO2 ·- SO3 2- Reducing free radicals can efficiently reduce nitrates under mild conditions. Studies have shown that CO2... ·- It can improve nitrogen conversion rate (E°(CO2 / CO2)). ·- )=-2.3eV,E°(NO3 - (N2) = -1.25 eV. In-phase advanced reduction requires the addition of additional chemical reagents, which may cause secondary pollution such as metal ions and organic matter. In contrast, heterogeneous advanced reduction technology has the advantages of requiring less additives, increasing nitrogen conversion rate while effectively converting minerals into CO2, reducing secondary pollution, and thus showing great promise for application in drinking water treatment.

[0004] Current research on heterogeneous advanced reduction technologies primarily focuses on titanium-based oxides, with some studies involving sulfides, spinels, and perovskites, all of which pose a risk of secondary catalyst contamination. Silver nanoparticles exhibit surface plasmon resonance effects, and silver modification can effectively improve photoelectron lifetime and reduction efficiency. However, the effectiveness of silver-modified TiO2 declines significantly after recycling, and recovery is difficult. Copper-iron bimetallic materials and titanium-based oxide materials both possess excellent photoelectric effects. Copper-iron-titanium oxide catalysts are characterized by their wide availability of materials, simple preparation, stable properties, and non-toxicity. In particular, their magnetic properties facilitate recycling, making them a green and efficient catalyst with promising potential in drinking water treatment, yet they have received limited research. Silver chloride (Ecb = -0.13 eV, Evb = -3.02 eV), as a catalytic material, can form heterojunctions with copper-iron-titanium oxides, reducing electron-hole recombination, increasing photon yield, and effectively improving pollutant reduction efficiency and product nitrogen selectivity. However, currently, there are no reports on systematic studies of using copper-iron-titanium mixed metal catalysts in conjunction with advanced reduction technologies to remove nitrate pollutants in drinking water treatment. Summary of the Invention

[0005] This invention is made to solve the above-mentioned problems, and aims to provide a silver chloride / silver-copper-iron-titanium oxide composite material, its preparation method and application.

[0006] This invention provides a method for preparing silver chloride / silver-copper-iron-titanium oxide composite materials, characterized by the following steps:

[0007] Step S1: Dissolve citric acid in ethanol solution, stir and sonicate to obtain mixture A;

[0008] Step S2: Add tetrabutyl titanate solution dropwise to mixture A, stir and sonicate to obtain mixture B;

[0009] Step S3: Add copper nitrate and ferric nitrate to deionized water, stir and mix evenly to obtain mixture C;

[0010] Step S4: Add mixture B dropwise to mixture C, adjust the pH, and stir vigorously to obtain mixture D;

[0011] Step S5: Mixture D undergoes a solvothermal reaction to obtain a precipitate;

[0012] Step S6: The precipitate is washed, centrifuged, dried and ground to obtain copper-iron-titanium oxide material;

[0013] Step S7: Weigh silver nitrate and copper-iron-titanium oxide materials and add them to a quartz reaction tube. Then add deionized water, stir well, and use a mercury lamp for photodeposition to obtain a mixed solution.

[0014] Step S8: Add sodium chloride solution dropwise to the mixed solution and stir to obtain a mixture;

[0015] Step S9: The mixture is centrifuged, washed, dried and ground to obtain silver chloride / silver-copper-iron-titanium oxide composite material.

[0016] The preparation method of silver chloride / silver-copper-iron-titanium oxide composite material provided by the present invention may also have the following characteristics: in step S1, the volume of ethanol solution is 15ml-30ml, in step S3, the volume of deionized water is 60ml-75ml, and the volume ratio of ethanol solution to deionized water in step S3 is 1:2-1:5.

[0017] The preparation method of silver chloride / silver-copper-iron-titanium oxide composite material provided by the present invention may also have the following feature: wherein the mass ratio of citric acid to tetrabutyl titanate is 1.2:1.

[0018] The preparation method of silver chloride / silver-copper-iron-titanium oxide composite material provided by the present invention may also have the following feature: wherein, in step S2, the ultrasonic time is 20min-40min.

[0019] The preparation method of silver chloride / silver-copper-iron-titanium oxide composite material provided by the present invention may also have the following feature: wherein the molar ratio of copper nitrate, iron nitrate and tetrabutyl titanate is 1-2:1-3:2-4.

[0020] The method for preparing silver chloride / silver-copper-iron-titanium oxide composite material provided by the present invention may also have the following feature: in step S4, sodium hydroxide is used to adjust the pH to 9.0-12.0.

[0021] The preparation method of silver chloride / silver-copper-iron-titanium oxide composite material provided by the present invention may also have the following characteristics: in step S5, when the solvothermal reaction is carried out, the reaction temperature is 140℃-180℃ and the reaction time is 14h-18h.

[0022] The preparation method of silver chloride / silver-copper-iron-titanium oxide composite material provided by the present invention may also have the following characteristics: wherein the molar ratio of silver nitrate to sodium chloride is 5:1, and the mass percentage of silver chloride / silver in the silver chloride / silver-copper-iron-titanium oxide composite material is 20%-50%.

[0023] The present invention also provides a silver chloride / silver-copper-iron-titanium oxide composite material, characterized in that it is prepared by the above-described method for preparing silver chloride / silver-copper-iron-titanium oxide composite material.

[0024] This invention also provides the application of the above-mentioned silver chloride / silver-copper-iron-titanium oxide composite material in drinking water treatment through photocatalytic reduction of nitrates.

[0025] The role and effect of invention

[0026] According to the present invention, a method for preparing a silver chloride / silver-copper-iron-titanium oxide composite material is first prepared by a modified one-time solvothermal method to obtain copper-iron-titanium oxide material, and then silver chloride / silver heterostructure is constructed on the surface of copper-iron-titanium oxide using silver chloride / silver as a modifier to obtain a silver chloride / silver-copper-iron-titanium oxide composite material. Furthermore, by adjusting the ratio of the three metals and the ratio of the modifier, a catalytic material with high nitrate reduction efficiency and high nitrogen selectivity can be prepared.

[0027] Furthermore, by controlling the pH of the mixture and the solvothermal reaction temperature, this invention can control the uniformity of the complexation process, thereby regulating the particle morphology of the synthesized material and ensuring uniform particle size. Simultaneously, by controlling the solvothermal reaction time, it can guarantee effective crystal growth time and stabilize the crystal structure. Moreover, this invention employs photodeposition and precipitation methods to construct silver chloride / silver heterojunctions on the surface of copper-iron-titanium oxides, improving the photoluminescence yield, reducing electron-hole recombination, effectively increasing reduction efficiency, and exhibiting stability and recyclability. Therefore, the silver chloride / silver-copper-iron-titanium oxide composite material prepared by this invention can serve as an advanced reduction catalyst for photocatalytic removal of nitrate contaminants from drinking water, exhibiting high catalytic efficiency and high nitrogen conversion rate, while also being easily recoverable magnetically and having a high reusability rate.

[0028] In summary, the preparation method and production process of this invention are simple, the raw materials are widely available, and the prepared silver chloride / silver-copper-iron-titanium oxide composite material has the characteristics of high degradation efficiency, no pollution of products (mainly nitrogen gas), low chemical reagent dosage, easy magnetic recovery, and multiple recycling. It has broad application prospects in removing nitrate pollution from drinking water. Attached Figure Description

[0029] Figure 1 This is a schematic flowchart of the preparation method of silver chloride / silver-copper-iron-titanium oxide composite material in the embodiments of the present invention;

[0030] Figure 2 The XRD patterns of copper-iron-titanium oxide materials and silver chloride in the silver chloride / silver-copper-iron-titanium oxide composite material prepared in Example 1 of the present invention are shown.

[0031] Figure 3 These are SEM images of silver chloride / silver-copper-iron-titanium oxide composite materials prepared under different metal contents in Example 3 of the present invention;

[0032] Figure 4 The image shows the effect of silver chloride / silver-copper-iron-titanium oxide composite material with a mass percentage of 40% silver chloride on the removal of 1 mM nitrate in Test Example 1 of the present invention.

[0033] Figure 5 The graph shows the effect of silver chloride / silver-copper-iron-titanium oxide composite material prepared in different proportions of three metals in Test Example 2 of the present invention on the removal of 1mM nitrate.

[0034] Figure 6 The graph shows the effect of a silver chloride / silver-copper-iron-titanium oxide composite material with a silver chloride / silver mass percentage of 40% on nitrate removal in deionized water, tap water, and simulated groundwater in Test Example 1 of the present invention. Detailed Implementation

[0035] To make the technical means, creative features, objectives and effects of the present invention easy to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate the silver chloride / silver-copper-iron-titanium oxide composite material of the present invention, its preparation method and application.

[0036] <Example 1>

[0037] Figure 1 This is a schematic flowchart illustrating the preparation method of silver chloride / silver-copper-iron-titanium oxide composite material in an embodiment of the present invention.

[0038] like Figure 1 As shown, the preparation method of a silver chloride / silver-copper-iron-titanium oxide composite material in this embodiment includes the following steps:

[0039] Step S1: Dissolve citric acid in an ethanol solution, stir and sonicate to obtain mixture A. The specific process is as follows:

[0040] Add 7.2 mmol of citric acid monohydrate to 15 ml of ethanol solution, stir well and sonicate for 10 min to obtain mixture A.

[0041] Step S2: Add tetrabutyl titanate solution dropwise to mixture A, stir and sonicate to obtain mixture B. The specific process is as follows:

[0042] Add 6 mmol of tetrabutyl titanate dropwise to mixture A, stir for 30 min, and then sonicate for 30 min to obtain mixture B.

[0043] Step S3: Add copper nitrate and ferric nitrate to deionized water, stir and mix thoroughly to obtain mixture C. The specific process is as follows:

[0044] Add 2 mmol Cu(NO3)3·3H2O and 4 mmol Fe(NO3)3·9H2O to 75 ml of deionized water, stir well, and obtain mixture C.

[0045] Step S4: Add mixture B dropwise to mixture C, adjust the pH, and stir vigorously to obtain mixture D. The specific process is as follows:

[0046] Add mixture B dropwise to mixture C, adjust the pH of the solution to 10.0 using 5 mol / L NaOH, and stir vigorously for 1 hour to disperse the suspension evenly, thus obtaining mixture D.

[0047] Step S5: Mixture D undergoes a solvothermal reaction to obtain a precipitate. The specific process is as follows:

[0048] The mixture D was transferred into a 110ml polytetrafluoroethylene reactor and placed in an oven for a solvothermal reaction at a temperature of 180±2℃ for 16 hours. After the reactor cooled naturally to room temperature, the supernatant was discarded to obtain the precipitate.

[0049] Step S6: The precipitate is washed, centrifuged, dried, and ground to obtain copper-iron-titanium oxide material. The specific process is as follows:

[0050] The precipitate was washed with ethanol and deionized water respectively and centrifuged three times at 10,000 rpm for 10 min. The resulting solid was dried in an oven at 80℃ for 8–12 h. After drying, it was ground into a powder using an agate mortar to obtain copper-iron-titanium oxide material (CuFe2Ti3O). x ).

[0051] Step S7: Weigh silver nitrate and copper-iron-titanium oxide materials and add them to a quartz reaction tube. Then add deionized water, stir well, and perform photodeposition using a mercury lamp to obtain a mixed solution. The specific process is as follows:

[0052] Weigh 0.2g of copper-iron-titanium oxide material. Take silver nitrate from the AgNO3 mother liquor, ensuring the AgCl / Ag content in the prepared silver chloride / silver-copper-iron-titanium oxide composite material reaches 40wt%, and add it to a quartz reaction tube. Add 50ml of deionized water, stir thoroughly, and then place the quartz reaction tube in a photoreactor. Use a 500W mercury lamp as the light source. The reaction time is 3 hours. During the reaction, use a magnetic stirrer at 100-120 rpm. After the reaction is complete, allow the reaction tube to cool naturally to room temperature to obtain a mixed solution (AgNO3 / Ag-CuFe2Ti3O). x ).

[0053] Step S8: Add sodium chloride solution dropwise to the mixed solution, stir, and obtain a mixture. The specific process is as follows:

[0054] Add 9.4 ml of 10 mmol sodium chloride solution dropwise to the mixed solution and stir at room temperature for 12 h to obtain the mixture.

[0055] Step S9: The mixture is centrifuged, washed, dried, and ground to obtain silver chloride / silver-copper-iron-titanium oxide composite material. The specific process is as follows:

[0056] The mixture was centrifuged and washed three times with ethanol and deionized water, respectively. The resulting solid was dried in an oven at 80°C for 12 hours to obtain silver chloride / silver-copper-iron-titanium oxide composite material (AgCl / Ag-CuFe2Ti3O). x ).

[0057] In this embodiment, the molar ratio of added copper nitrate, iron nitrate, and tetrabutyl titanate is 1:2:3. The mass percentage of silver chloride / silver in the silver chloride / silver-copper-iron-titanium oxide composite material prepared in this embodiment is 40wt% (i.e., the preparation product in this embodiment is 40wt% AgCl / Ag-CuFe2Ti3O). x ).

[0058] The surface physicochemical properties of the silver chloride / silver-copper-iron-titanium oxide composite material prepared in this embodiment were obtained through testing and are as follows: CuFe2Ti3O x The average pore size is 2.35 nm, and the specific surface area is 91.08 m². 2 / g, with an average particle size of 50–185 nm; AgCl specific surface area is 4.10 m² / g. 2 / g; The specific surface area of ​​the silver chloride / silver-copper-iron-titanium oxide composite material is 67.34m². 2 / g.

[0059] Figure 2 The image shows the XRD patterns of copper-iron-titanium oxide materials and silver chloride in the silver chloride / silver-copper-iron-titanium oxide composite material prepared in Example 1 of this invention.

[0060] like Figure 2 As shown, the composite material is mainly composed of silver chloride, copper ferrite and titanium dioxide crystals.

[0061] <Example 2>

[0062] In this embodiment, based on the same preparation method as in Example 1, the amount of ethanol solution in step S1 was replaced with 18 ml, 22.5 ml or 30 ml, and the ultrasonic time after stirring in step S2 was replaced with 40 min. Subsequent preparation was then carried out to obtain the silver chloride / silver-copper-iron-titanium oxide composite material.

[0063] In this embodiment, the volume ratio of ethanol solution to deionized water was controlled to be 1:4, 1:3, or 1:2 during preparation, and the mixture was sonicated for 40 minutes after stirring. This resulted in the preparation of silver chloride / silver-copper-iron-titanium oxide composite materials. The preparation product obtained in Example 1 under the conditions of a volume ratio of ethanol solution to deionized water of 1:5 and sonication for 30 minutes after stirring was compared with the product obtained in Example 1. It can be seen that the dispersion of titanium elements increases with the increase of the proportion of ethanol solution and the increase of sonication time in the solvothermal reaction.

[0064] <Example 3>

[0065] In this embodiment, based on the same preparation method as in Example 1, only the molar ratio of added copper nitrate, iron nitrate and tetrabutyl titanate was replaced with 2:1:3, 1:1:2 or 1:3:4, and the corresponding preparation was carried out to obtain silver chloride / silver-copper-iron-titanium oxide composite material.

[0066] Figure 3 This is a SEM image of the silver chloride / silver-copper-iron-titanium oxide composite material prepared under different metal contents in Example 3 of the present invention. Figure 3 In the images (1), (2), (3), and (4), respectively, are SEM images of silver chloride / silver-copper-iron titanium oxide composite materials prepared under conditions where the molar ratios of copper nitrate, iron nitrate, and tetrabutyl titanate are 2:1:3, 1:1:2, 1:2:3, and 1:3:4.

[0067] like Figure 3 As shown, copper-iron-titanium metal oxide materials prepared under different molar ratios of copper nitrate, iron nitrate, and tetrabutyl titanate all exhibit good crystallinity with particle sizes ranging from 50 nm to 185 nm.

[0068] <Example 4>

[0069] In this embodiment, based on the same preparation method as in Example 1, only the temperature of the solvothermal reaction in step S5 was adjusted to 140°C or 160°C, and the reaction time was adjusted to 14h or 18h, and the silver chloride / silver-copper-iron-titanium oxide composite material was prepared accordingly.

[0070] Testing of the prepared products showed that the silver chloride / silver-copper-iron-titanium oxide composite material finally prepared in this embodiment under solvothermal reaction conditions of 140℃ and 14h already exhibited good catalytic performance. At higher temperatures and longer reaction times, such as 160℃ and 18h, the catalytic performance of the material was further improved.

[0071] <Test Example 1>

[0072] In this test example, the silver chloride / silver-copper-iron-titanium oxide composite material prepared in Example 1 was used as a photocatalyst to reduce nitrate to nitrogen gas for corresponding performance testing. The specific test method is as follows:

[0073] 0.04 g of the silver chloride / silver-copper-iron-titanium oxide composite material (40 wt% AgCl / Ag-CuFe2Ti3O) prepared in Example 1 was used. x 200 ml of a mixture of nitrate and 1 mM nitrate solution was added to a quartz reactor and stirred in the dark for 30 min until adsorption equilibrium was reached. Then, formic acid, a hole-trapping agent, was added to bring the formic acid concentration in the reactor to 3 mM. After the circulation system stabilized, the photoreactor was turned on, and a 500 W mercury lamp was preheated for 5 min before being placed in the quartz reactor for photoreaction at room temperature, with the circulating cooling water temperature at 20 ± 1 °C. 3 ml of the mixture was taken at regular intervals for measurement. The mixture was then centrifuged at 10,000 rpm for 10 min to separate the solid and liquid components, and the supernatant was used for measurement. The concentrations of nitrate, nitrite, and formate were determined using ion chromatography (Thermo Fisher Scientific, Dionex™ Aquion™), ammonium was determined using UV spectrophotometry (Hach, DR6000), total nitrogen was quantitatively analyzed using a total organic carbon analyzer (Shimadzu, TOC-L), and nitrogen was indirectly calculated from the total nitrogen and total solution detection single-element balance to obtain the nitrate removal rate and nitrogen conversion rate.

[0074] Figure 4 This is a graph showing the removal effect of a silver chloride / silver-copper-iron-titanium oxide composite material with a silver chloride / silver mass percentage of 40% in Test Example 1 of the present invention on 1 mM nitrate. The vertical axis of the graph represents the changes in the concentrations of total nitrogen, nitrate nitrogen, nitrite nitrogen, and ammonia nitrogen over time.

[0075] like Figure 4 As shown, using silver chloride / silver-copper-iron-titanium oxide composite material as a catalyst can achieve good removal effect of nitrate. During the nitrate removal process, formic acid is adsorbed on the surface of copper ferrite material and recombines with vacancies to generate carbon dioxide free radicals (CO2). - Nitrate is adsorbed on the surface of copper-iron-titanium oxide materials and decomposes into easily reduced intermediate products. The main pathway is that the intermediate products are reduced to nitrogen gas by carbon dioxide free radicals. A small amount of nitrite and ammonium ions are generated during the reaction. The added hole scavenging agent formic acid is consumed at the end of the reduction process, and no secondary pollution is caused.

[0076] <Test Example 2>

[0077] In this test example, the silver chloride / silver-copper-iron-titanium oxide composite materials prepared in Examples 1 and 3 at different copper-iron-titanium molar ratios were used to perform performance testing on the photocatalyst for reducing 1mM nitrate to nitrogen. The specific test method was the same as that in Test Example 1, and the photoreaction time was controlled to be greater than 150 min. Figure 5 The image shows the effect of silver chloride / silver-copper-iron-titanium oxide composite material prepared in different proportions of the three metals in Test Example 2 of the present invention on the removal of 1mM nitrate.

[0078] like Figure 5 As shown, after a reaction time exceeding 150 min, the silver chloride / silver-copper-iron-titanium oxide composite materials prepared with copper-iron-titanium molar ratios of 3:1:4, 2:1:3, 1:1:2, 1:2:3, and 1:3:4, respectively, achieved nitrate removal rates of 42.5%, 57.4%, 77.3%, 95.6%, and 72.1%. Among them, the nitrogen conversion rates of the silver chloride / silver-copper-iron-titanium oxide composite materials prepared with copper-iron-titanium molar ratios of 2:1:3 to 1:3:4 were all above 80%.

[0079] <Test Example 3>

[0080] In this test example, the silver chloride / silver-copper-iron-titanium oxide composite material prepared in Example 1 was applied to remove nitrates from simulated groundwater for performance testing. It was also applied to remove nitrates from deionized water and tap water for comparative testing. In this test example, the simulated groundwater quality was based on reported characteristics of groundwater in the Hexi Corridor region. A mixed solution of 2mM MgSO4, 2mM Na2SO4, 1mM CaCl2, 2mM NaCl, 2mM NaHCO3, 2mM KNO3, and 3 mg-C / L humic acid was prepared for groundwater simulation experiments. The specific test methods are as follows:

[0081] Weigh 0.08g of silver chloride / silver-copper-iron-titanium oxide composite material (40wt% AgCl / Ag-CuFe2Ti3O) x Add 200 ml of formic acid and 200 ml of water sample (deionized water, tap water, or simulated groundwater) to the quartz reaction trap. The subsequent procedures are the same as in Test Example 1, except that the formic acid concentration is replaced with 6 mM.

[0082] Figure 6 The graph shows the effect of a silver chloride / silver-copper-iron-titanium oxide composite material with a silver chloride / silver mass percentage of 40% on nitrate removal in deionized water, tap water, and simulated groundwater in Test Example 1 of the present invention.

[0083] like Figure 6As shown, the silver chloride / silver-copper-iron-titanium oxide composite material prepared in Example 1 has high nitrate removal rate and nitrogen conversion rate for deionized water, tap water and simulated groundwater. The nitrate removal rates after 3 hours are 94.6%, 87.4% and 80.9% respectively, and the nitrogen conversion rate is over 70%.

[0084] The role and effect of the embodiments

[0085] As shown in Examples 1-4, the preparation method of the silver chloride / silver-copper-iron-titanium oxide composite material of the present invention firstly prepares copper-iron-titanium oxide material by a modified one-time solvothermal method, and then uses silver chloride / silver as a modifier to construct silver chloride / silver heterojunction on the surface of copper-iron-titanium oxide by photodeposition and precipitation methods to prepare silver chloride / silver-copper-iron-titanium oxide composite material. This method can improve the quantum yield, reduce electron-hole recombination, effectively improve the reduction efficiency, and has the characteristics of being stable and reusable multiple times.

[0086] As can be seen from Examples 1 and 4, the present invention can control the uniformity of the complexation process by improving the pH of the mixture and the solvothermal reaction temperature, thereby regulating the particle morphology of the synthesized material and making the particle size uniform; at the same time, by controlling the solvothermal reaction time to 16h, the effective crystal growth time can be guaranteed, the crystal structure can be stabilized, and the size of the prepared copper-iron-titanium oxide particles is 50-185nm.

[0087] As shown in Test Example 1, the silver chloride / silver-copper-iron-titanium oxide composite material prepared in this invention can achieve good removal effect when used as a photocatalyst to reduce nitrate to nitrogen.

[0088] As can be seen from Example 3 and Test Example 2, the preparation method of the present invention can prepare catalytic materials with high nitrate reduction efficiency and high nitrogen selectivity by adjusting the proportions of the three metals and the modifier. Furthermore, when the silver chloride / silver-copper-iron-titanium oxide composite materials prepared under different copper-iron-titanium molar ratios are applied to the photocatalyst for nitrate reduction, the nitrogen conversion rate is above 80%, and excellent nitrate removal rates can be obtained. In particular, when the copper-iron-titanium molar ratio is 1:2:3, a nitrate removal rate of 95.6% can be achieved.

[0089] As shown in Test Example 3, the silver chloride / silver-copper-iron-titanium oxide composite material prepared in this invention can remove nitrates in different water qualities and has good applicability.

[0090] In summary, the preparation method and production process of this invention are simple, the raw materials are widely available, and the prepared silver chloride / silver-copper-iron-titanium oxide composite material has the characteristics of high degradation efficiency, no pollution of products (mainly nitrogen gas), low chemical reagent dosage, easy magnetic recovery, and multiple recycling. It has broad application prospects in removing nitrate pollution from drinking water.

[0091] The above embodiments are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A method for preparing a silver chloride / silver-copper-iron-titanium oxide composite material, characterized in that, Includes the following steps: Step S1: Dissolve citric acid in ethanol solution, stir and sonicate to obtain mixture A; Step S2: Add tetrabutyl titanate solution dropwise to the mixture A, stir and sonicate to obtain mixture B; Step S3: Add copper nitrate and ferric nitrate to deionized water, stir and mix evenly to obtain mixture C; Step S4: Add the mixture B dropwise to the mixture C, adjust the pH, and stir vigorously to obtain mixture D; Step S5, the mixture D undergoes a solvothermal reaction to obtain a precipitate; Step S6: The precipitate is washed, centrifuged, dried and ground to obtain copper-iron-titanium oxide material; Step S7: Weigh silver nitrate and the copper-iron-titanium oxide material and add them to a quartz reaction tube. Then add deionized water, stir evenly, and use a mercury lamp for photodeposition to obtain a mixed solution. Step S8: Add sodium chloride solution dropwise to the mixed solution and stir to obtain a mixture; Step S9: The mixture is centrifuged, washed, dried, and ground to obtain a silver chloride / silver-copper-iron-titanium oxide composite material. In step S1, the volume of the ethanol solution is 15ml-30ml. In step S3, the volume of the deionized water is 60ml-75ml. The volume ratio of the ethanol solution to the deionized water in step S3 is 1:2 to 1:

5. In step S2, the ultrasound time is 20 min-40 min.

2. The method for preparing the silver chloride / silver-copper-iron-titanium oxide composite material according to claim 1, characterized in that: in, The molar ratio of citric acid to tetrabutyl titanate is 1.2:

1.

3. The preparation method of the silver chloride / silver-copper-iron-titanium oxide composite material according to claim 1, characterized in that: in, The molar ratio of copper nitrate, ferric nitrate and tetrabutyl titanate is 1~2:1~3:2~4.

4. The preparation method of the silver chloride / silver-copper-iron-titanium oxide composite material according to claim 1, characterized in that: in, In step S4, sodium hydroxide is used to adjust the pH to 9.0-12.

0.

5. The method for preparing the silver chloride / silver-copper-iron-titanium oxide composite material according to claim 1, characterized in that: in, In step S5, the solvothermal reaction is carried out at a temperature of 140℃-180℃ for a reaction time of 14 h-18 h.

6. The method for preparing the silver chloride / silver-copper-iron-titanium oxide composite material according to claim 1, characterized in that: in, The molar ratio of silver nitrate to sodium chloride is 5:1, and the mass percentage of silver chloride / silver in the silver chloride / silver-copper-iron-titanium oxide composite material is 20%-50%.

7. A silver chloride / silver-copper-iron-titanium oxide composite material, characterized in that, The composite material is prepared by the method described in any one of claims 1 to 6.

8. The application of the silver chloride / silver-copper-iron-titanium oxide composite material as described in claim 7 in drinking water treatment through photocatalytic reduction of nitrates.

Images