Modified TiO2 photocatalyst as well as preparation method and application thereof

Abstract

The invention discloses a modified TiO2 photocatalyst as well as a preparation method and application thereof, and belongs to the technical field of agricultural waste resource utilization. The preparation method comprises the following steps: adding a polyferric sulfate solution and a polyacrylamide solution into wastewater to obtain a mixed solution, uniformly mixing the mixed solution, and then standing until solid-liquid separation to obtain flocculate; drying and crushing the flocculate, performing primary calcination in a nitrogen atmosphere, and cleaning and drying after the primary calcination is completed to obtain biochar; the preparation method comprises the following steps: by taking absolute ethyl alcohol as a solvent, tetra-n-butyl titanate as a titanium source and nitric acid as an inhibitor, adding biochar, uniformly stirring, and carrying out stirring reaction to obtain a product; and carrying out secondary calcination on the product to obtain the modified TiO2 photocatalyst. According to the method disclosed by the invention, TiO2 is modified through the culture wastewater flocculate, a new thought and technical guidance are provided for green and efficient treatment of livestock and poultry culture wastes, and a waste resource utilization treatment mode of'treating pollution with pollution 'is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural waste resource utilization, and more specifically to a modified TiO2 photocatalyst and a preparation method and application thereof. Background Art

[0002] The rapid development of the breeding industry has made breeding pollution the main source of agricultural pollution. A lot of wastewater will be discharged during the breeding process, with feces, urine and comprehensive wastewater generated by house washing as the main source of wastewater, which contains a large amount of COD (chemical oxygen demand), ammonia nitrogen, bacteria, suspended solids, etc. The effective treatment of farm wastewater has become the main factor restricting the healthy and sustainable development of livestock and poultry breeding. The scale of livestock and poultry breeding continues to increase, and the total amount of breeding is growing at an annual rate of 8%. If the breeding wastewater is directly discharged into the water body or the storage location is not suitable, it will be washed into the water body by rainwater, which may cause serious deterioration of the quality of surface water or groundwater, and cause increasing harm to the environment.

[0003] Titanium dioxide, with the chemical formula TiO2, is a white solid or powder at room temperature. Its relative molecular mass is 79.9. It is chemically stable, non-toxic, and low-cost. It is a green and environmentally friendly photocatalyst with the most promising development prospects. Its excellent photocatalytic performance has made it applicable to many fields, such as air, water, and fluid purification. However, due to its low utilization rate of visible light and the photogenerated electron-hole pairs (e - / h + )'s recombination rate, which hinders the application of TiO2 in actual production. Summary of the invention

[0004] Based on this, the present invention provides a modified TiO2 photocatalyst and its preparation method and application. The present invention modifies TiO2 by flocculants from aquaculture wastewater, provides new ideas and technical guidance for the green and efficient treatment of livestock and poultry aquaculture wastes, and realizes a waste treatment model of "treating pollution with pollution" for resource utilization.

[0005] The first object of the present invention is to provide a method for preparing a modified TiO2 photocatalyst, comprising the following steps:

[0006] Adding a polyferric sulfate solution and a polyacrylamide solution to wastewater to obtain a mixed solution, mixing the mixed solution evenly, and then standing the mixed solution until solid-liquid separation to obtain floccules;

[0007] After the flocculent is dried and crushed, it is calcined once at 600-900°C in a nitrogen atmosphere, and after the calcination is completed, it is washed and dried to obtain biochar;

[0008] Anhydrous ethanol is used as solvent, tetrabutyl titanate is used as titanium source, nitric acid is used as inhibitor, biochar is added and stirred evenly, and then stirred to react to obtain the product;

[0009] The product is subjected to secondary calcination at 300-600° C. to obtain a modified TiO2 photocatalyst.

[0010] In one embodiment of the present invention, the volume ratio of wastewater to polyferric sulfate solution is 1:0.1, and the concentration of polyferric sulfate solution is 2-12 g / L;

[0011] The volume ratio of wastewater to polyacrylamide solution is 1:0.3, and the concentration of polyacrylamide solution is 0.1-0.9 g / L.

[0012] In one embodiment of the present invention, the primary calcination condition is calcination at 600-900° C. for 2 h, with a heating rate of 5° C. / min.

[0013] In one embodiment of the present invention, the volume ratio of tetrabutyl titanate, anhydrous ethanol and nitric acid is 1-2:2:3; and the concentration of nitric acid is 0.1 mol / L.

[0014] In one embodiment of the present invention, the ratio of tetrabutyl titanate to biochar is 15-20 ml: 0.1-4 g; and the stirring reaction is carried out at 75-80° C. for 3-3.5 hours.

[0015] In one embodiment of the present invention, the secondary calcination condition is calcination at 300-600° C. for 3 h, and the heating rate is 5° C. / min.

[0016] The second object of the present invention is to provide a modified TiO2 photocatalyst prepared by the above preparation method. The third object of the present invention is to provide the use of the above modified TiO2 photocatalyst in degrading wastewater.

[0017] In one embodiment of the present invention, the wastewater is antibiotic wastewater or livestock and poultry breeding wastewater.

[0018] In one embodiment of the present invention, the antibiotic is sulfamethoxazole.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The invention uses aquaculture wastewater flocculants and tetrabutyl titanate to prepare a modified TiO2 photocatalytic material, so that the prepared modified TiO2 photocatalytic material can effectively degrade antibiotics (sulfamethoxazole) and livestock and poultry aquaculture wastewater in water under sunlight.

[0021] The present invention utilizes aquaculture wastewater and tetrabutyl titanate to prepare modified TiO2 photocatalytic material, provides a solution for the treatment of aquaculture wastewater, realizes the treatment mode of "using pollution to treat pollution" for resource utilization of waste, and provides new ideas and technical guidance for the green and efficient treatment of livestock and poultry breeding waste.

[0022] When preparing TiO2, biochar is added. Biochar contains non-metallic elements and metallic elements. After doping, impurity energy levels are formed between the energy band gaps. Light with lower energy can also excite electrons, broadening the light response range. At the same time, doping creates lattice defects, which is conducive to the formation of more active centers. This improves the catalytic ability of the photocatalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the SEM image of F2 / TiO2.

[0024] Figure 2 XRD patterns of F0TiO2 and F2 / TiO2.

[0025] Figure 3 The degradation efficiency of sulfamethoxazole in water by different photocatalytic materials under simulated sunlight.

[0026] Figure 4 The degradation efficiency of sulfamethoxazole in water under simulated sunlight with different added amounts of F2 / TiO2.

[0027] Figure 5 The degradation efficiency of sulfamethoxazole in water by F2 / TiO2 under simulated sunlight is shown in Figure 2 under the conditions of different concentrations of sulfamethoxazole solution.

[0028] Figure 6 The degradation efficiency of sulfamethoxazole in water by F2 / TiO2 under simulated sunlight under different pH conditions of sulfamethoxazole solution.

[0029] Figure 7 The degradation efficiency of aquaculture wastewater by F2 / TiO2 under simulated sunlight.

[0030] Figure 8 This is the degradation efficiency of aquaculture wastewater by F2 / TiO2 under actual sunlight.

[0031] Fig. 9 It is the free radical contribution rate of F2 / TiO2 photocatalytic removal of organic matter. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Due to the low utilization rate of visible light by TiO2 and the photogenerated electron-hole pairs (e- / h + ) is an obstacle to the application of TiO2 in actual production. There are a large number of non-metallic elements (C, N, P, etc.) and heavy metal elements (Cu, Zn, etc.) in aquaculture wastewater. Water treatment flocculants such as polyferric sulfate (SPFS) and cationic polyacrylamide (CPAM) also contain elements such as Fe and N, and these elements can be used to dope and modify photocatalytic materials to improve their catalytic efficiency. Therefore, the present invention is theoretically feasible to use aquaculture wastewater flocculants to modify photocatalysts (TiO2). Using aquaculture wastewater flocculants to modify TiO2 for the treatment of aquaculture wastewater can truly realize the resource utilization of waste treatment mode of "treating pollution with pollution". By doping or depositing some metal elements (Fe, Cu, Zn) or non-metallic elements (C, N, P) on the surface of TiO2, its visible light response can be effectively improved, and the photocatalytic efficiency can be improved.

[0034] When tetrabutyl titanate is used to prepare titanium dioxide, the rapid hydrolysis of tetrabutyl titanate will generate the intermediate product Ti(OH)4. The addition of nitric acid can inhibit the hydrolysis of tetrabutyl titanate. In the process of preparing titanium dioxide, the tetrabutyl titanate is added to anhydrous ethanol, and then nitric acid and biochar are added for stirring. During the stirring process, hydrolysis reaction and dehydroxylation reaction occur. The butyl titanate is converted into dibutyl titanate hydrolyzate (i.e., TiO2 with water and hydroxyl groups on the surface) by hydrolysis reaction, and then heated for dehydroxylation reaction to form titanium dioxide. During the reaction, ions used for semiconductor doping are added, such as transition metal ions (Fe 3+ 、Co 2+ , Cu 2+ After doping, impurity energy levels are formed in the energy band gap, and light with lower energy can also excite electrons, thus broadening the light response range. At the same time, doping causes lattice defects, which is conducive to the formation of more active centers. This improves the catalytic ability of the photocatalyst.

[0035] The following experimental methods and detection methods, unless otherwise specified, are conventional methods; the following reagents and raw materials, unless otherwise specified, are commercially available reagents and raw materials. The livestock and poultry breeding wastewater used in the present invention is the wastewater after flushing pig feces and urine in the pig farm. The pH of the livestock and poultry breeding wastewater used is 3.27-3.91.

[0036] Example 1

[0037] Step 1: Preparation of biochar from wastewater flocculants

[0038] 1.1. Take 1L of livestock and poultry wastewater and filter out impurities with gauze;

[0039] 1.2. Add 100 mL of 5 g / L polyferric sulfate solution (SPFS) and 300 mL of 0.6 g / L cationic polyacrylamide (CPAM) to 1 L of wastewater to obtain a mixed solution;

[0040] 1.3. Stir the mixed solution magnetically for 1 h at a speed of 600 r min -1 The purpose of stirring is to fully mix and disperse the added flocculant in the water, and to promote the rapid aggregation of suspended matter in the water to form larger particles). After the stirring is completed, the mixture is allowed to stand until the solid and liquid are separated, and then the upper solid layer, i.e., flocculants, is removed.

[0041] 1.4. Dry the taken out flocculants at 80℃, crush them, and grind them through a 100-mesh sieve;

[0042] 1.5. Spread the obtained powder in a corundum crucible, place it in a tubular resistance furnace, set the heating rate to 5°C / min under nitrogen protection, and calcine at 900°C for 2h. After the calcination is completed, wait for the product to cool naturally to room temperature and then take it out;

[0043] 1.6. The product was treated with 1 mol L -1 The residue was washed with HCl and then with deionized water until the filtrate was neutral, and then dried in an oven at 80 °C to obtain biochar.

[0044] Step 2: Preparation of modified TiO2 photocatalyst using biochar and tetrabutyl titanate

[0045] 2.1. Slowly add 15 mL of tetrabutyl titanate dropwise into 20 mL of anhydrous ethanol, and then add 30 mL of 0.1 mol L -1 nitric acid solution (acidified to control the hydrolysis rate of tetrabutyl ester and inhibit the formation of precipitation to form a stable sol); then 0.1g of biochar was added to the system, and the system was vigorously stirred for 1h;

[0046] 2.2. Heat the system in a constant temperature water bath at 80°C for 3 hours. Wash the treated samples three times with deionized water and dry at 80°C.

[0047] 2.3. Then, the sample was placed in a tube furnace, the heating rate was set to 5°C / min, and calcined at 450°C for 3h. After it cooled naturally, the sample was taken out and ground through a 100-mesh sieve to obtain a modified TiO2 photocatalyst, which was recorded as F. 0.1 / TiO2.

[0048] Example 2

[0049] Step 1: Preparation of biochar from wastewater flocculants

[0050] 1.1. Take 1L of livestock and poultry wastewater and filter out impurities with gauze;

[0051] 1.2. Add 100 mL of 5 g / L polyferric sulfate solution (SPFS) and 300 mL of 0.6 g / L cationic polyacrylamide (CPAM) to 1 L of wastewater to obtain a mixed solution;

[0052] 1.3. Stir the mixed solution magnetically for 1 h at a speed of 600 r min -1 The purpose of stirring is to fully mix and disperse the added flocculant in the water, and to promote the rapid aggregation of suspended matter in the water to form larger particles). After the stirring is completed, the mixture is allowed to stand until the solid and liquid are separated, and then the upper solid layer, i.e., flocculants, is removed.

[0053] 1.4. Dry the taken out flocculants at 80℃, crush them, and grind them through a 100-mesh sieve;

[0054] 1.5. Spread the obtained powder in a corundum crucible, place it in a tubular resistance furnace, set the heating rate to 5°C / min under nitrogen protection, and calcine at 900°C for 2h. After the calcination is completed, wait for the product to cool naturally to room temperature and then take it out;

[0055] 1.6. The product was treated with 1 mol L -1 The residue was washed with HCl and then with deionized water until the filtrate was neutral, and then dried in an oven at 80 °C to obtain biochar.

[0056] Step 2: Preparation of modified TiO2 photocatalyst using biochar and tetrabutyl titanate

[0057] 2.1. Slowly add 15 mL of tetrabutyl titanate dropwise into 20 mL of anhydrous ethanol, and then add 30 mL of 0.1 mol L -1 nitric acid solution (acidified to control the hydrolysis rate of tetrabutyl ester and inhibit the formation of precipitation to form a stable sol); then 0.25g of biochar was added to the system, and the system was vigorously stirred for 1h;

[0058] 2.2. Heat the system in a constant temperature water bath at 80°C for 3 hours. Wash the treated samples three times with deionized water and dry at 80°C.

[0059] 2.3. Then, the sample was placed in a tube furnace, the heating rate was set to 5°C / min, and calcined at 450°C for 3h. After it cooled naturally, the sample was taken out and ground through a 100-mesh sieve to obtain a modified TiO2 photocatalyst, which was recorded as F. 0.25 / TiO2.

[0060] Example 3

[0061] Step 1: Preparation of biochar from wastewater flocculants

[0062] 1.1. Take 1L of livestock and poultry wastewater and filter out impurities with gauze;

[0063] 1.2. Add 100 mL of 5 g / L polyferric sulfate solution (SPFS) and 300 mL of 0.6 g / L cationic polyacrylamide (CPAM) to 1 L of wastewater to obtain a mixed solution;

[0064] 1.3. Stir the mixed solution magnetically for 1 h at a speed of 600 r min -1 The purpose of stirring is to fully mix and disperse the added flocculant in the water, and to promote the rapid aggregation of suspended matter in the water to form larger particles). After the stirring is completed, the mixture is allowed to stand until the solid and liquid are separated, and then the upper solid layer, i.e., flocculants, is removed.

[0065] 1.4. Dry the taken out flocculants at 80℃, crush them, and grind them through a 100-mesh sieve;

[0066] 1.5. Spread the obtained powder in a corundum crucible, place it in a tubular resistance furnace, set the heating rate to 5°C / min under nitrogen protection, and calcine at 900°C for 2h. After the calcination is completed, wait for the product to cool naturally to room temperature and then take it out;

[0067] 1.6. The product was treated with 1 mol L -1 The residue was washed with HCl and then with deionized water until the filtrate was neutral, and then dried in an oven at 80 °C to obtain biochar.

[0068] Step 2: Preparation of modified TiO2 photocatalyst using biochar and tetrabutyl titanate

[0069] 2.1. Slowly add 15 mL of tetrabutyl titanate dropwise into 20 mL of anhydrous ethanol, and then add 30 mL of 0.1 mol L -1 Nitric acid solution (acidified to control the hydrolysis rate of tetrabutyl ester and inhibit the formation of precipitation to form a stable sol); then 1g of biochar was added to the system and the system was vigorously stirred for 1h;

[0070] 2.2. Heat the system in a constant temperature water bath at 80°C for 3 hours. Wash the treated samples three times with deionized water and dry at 80°C.

[0071] 2.3. Then, the sample was placed in a tube furnace, the heating rate was set to 5°C / min, and calcined at 450°C for 3h. After it cooled down naturally, the sample was taken out and ground through a 100-mesh sieve to obtain a modified TiO2 photocatalyst, which was recorded as F1 / TiO2.

[0072] Example 4

[0073] Step 1: Preparation of biochar from wastewater flocculants

[0074] 1.1. Take 1L of livestock and poultry wastewater and filter out impurities with gauze;

[0075] 1.2. Add 100 mL of 5 g / L polyferric sulfate solution (SPFS) and 300 mL of 0.6 g / L cationic polyacrylamide (CPAM) to 1 L of wastewater to obtain a mixed solution;

[0076] 1.3. Stir the mixed solution magnetically for 1 h (600 r min -1 ), stirring is to make the added flocculant fully mixed and dispersed in the water, and promote the rapid aggregation of suspended matter in the water to form larger particles), after the stirring is completed, let it stand until the solid and liquid are separated, and then the upper solid, i.e., flocculent, is removed;

[0077] 1.4. Dry the taken out flocculants at 80℃, crush them, and grind them through a 100-mesh sieve;

[0078] 1.5. Spread the obtained powder in a corundum crucible, place it in a tubular resistance furnace, set the heating rate to 5°C / min under nitrogen protection, and calcine at 900°C for 2h. After the calcination is completed, wait for the product to cool naturally to room temperature and then take it out;

[0079] 1.6. The product was treated with 1 mol L -1 The residue was washed with HCl and then with deionized water until the filtrate was neutral, and then dried in an oven at 80 °C to obtain biochar.

[0080] Step 2: Preparation of modified TiO2 photocatalyst using biochar and tetrabutyl titanate

[0081] 2.1. Slowly add 15 mL of tetrabutyl titanate dropwise into 20 mL of anhydrous ethanol, and then add 30 mL of 0.1 mol L -1 Nitric acid solution (acidified to control the hydrolysis rate of tetrabutyl ester and inhibit the formation of precipitation to form a stable sol); then 2g of biochar was added to the system and the system was vigorously stirred for 1h;

[0082] 2.2. Heat the system in a constant temperature water bath at 80°C for 3 hours. Wash the treated samples three times with deionized water and dry at 80°C.

[0083] 2.3. Then, the sample was placed in a tube furnace, the heating rate was set to 5°C / min, and calcined at 450°C for 3h. After it cooled naturally, the sample was taken out and ground through a 100-mesh sieve to obtain a modified TiO2 photocatalyst, which was recorded as F2 / TiO2. The element content of F2 / TiO2 is shown in Table 1.

[0084] Table 1 Element content of F2 / TiO2

[0085]

[0086] Example 5

[0087] Step 1: Preparation of biochar from wastewater flocculants

[0088] 1.1. Take 1L of livestock and poultry wastewater and filter out impurities with gauze;

[0089] 1.2. Add 100 mL of 5 g / L polyferric sulfate solution (SPFS) and 300 mL of 0.6 g / L cationic polyacrylamide (CPAM) to 1 L of wastewater to obtain a mixed solution;

[0090] 1.3. Stir the mixed solution magnetically for 1 h (600 r min -1 ), stirring is to make the added flocculant fully mixed and dispersed in the water, and promote the rapid aggregation of suspended matter in the water to form larger particles), after the stirring is completed, let it stand until the solid and liquid are separated, and then the upper solid, i.e., flocculent, is removed;

[0091] 1.4. Dry the taken out flocculants at 80℃, crush them, and grind them through a 100-mesh sieve;

[0092] 1.5. Spread the obtained powder in a corundum crucible, place it in a tubular resistance furnace, set the heating rate to 5°C / min under nitrogen protection, and calcine at 900°C for 2h. After the calcination is completed, wait for the product to cool naturally to room temperature and then take it out;

[0093] 1.6. The product was treated with 1 mol L -1 The residue was washed with HCl and then with deionized water until the filtrate was neutral, and then dried in an oven at 80 °C to obtain biochar.

[0094] Step 2: Preparation of modified TiO2 photocatalyst using biochar and tetrabutyl titanate

[0095] 2.1. Slowly add 15 mL of tetrabutyl titanate dropwise into 20 mL of anhydrous ethanol, and then add 30 mL of 0.1 mol L -1 Nitric acid solution (acidified to control the hydrolysis rate of tetrabutyl ester and inhibit the formation of precipitation to form a stable sol); then 4g of biochar was added to the system and the system was vigorously stirred for 1h;

[0096] 2.2. Heat the system in a constant temperature water bath at 80°C for 3 hours. Wash the treated samples three times with deionized water and dry at 80°C.

[0097] 2.3. Then, the sample was placed in a tube furnace, the heating rate was set to 5°C / min, and calcined at 450°C for 3h. After it cooled down naturally, the sample was taken out and ground through a 100-mesh sieve to obtain a modified TiO2 photocatalyst, which was recorded as F4 / TiO2.

[0098] Example 6

[0099] Step 1: Preparation of biochar from wastewater flocculants

[0100] 1.1. Take 1L of livestock and poultry wastewater and filter out impurities with gauze;

[0101] 1.2. Add 100 mL of 2 g / L polyferric sulfate solution (SPFS) and 300 mL of 0.1 g / L cationic polyacrylamide (CPAM) to 1 L of wastewater to obtain a mixed solution.

[0102] 1.3. Stir the mixed solution magnetically for 1 h (600 r min -1 ), stirring is to make the added flocculant fully mixed and dispersed in the water, and promote the rapid aggregation of suspended matter in the water to form larger particles), after the stirring is completed, let it stand until the solid and liquid are separated, and then the upper solid, i.e., flocculent, is removed;

[0103] 1.4. Dry the taken out flocculants at 80℃, crush them, and grind them through a 100-mesh sieve;

[0104] 1.5. Spread the obtained powder in a corundum crucible, place it in a tubular resistance furnace, set the heating rate to 5°C / min under nitrogen protection, and calcine at 600°C for 2h. After the calcination is completed, wait for the product to cool naturally to room temperature and then take it out;

[0105] 1.6. The product was treated with 1 mol L -1 The residue was washed with HCl and then with deionized water until the filtrate was neutral, and then dried in an oven at 80 °C to obtain biochar.

[0106] Step 2: Preparation of modified TiO2 photocatalyst using biochar and tetrabutyl titanate

[0107] 2.1. Slowly add 10 mL of tetrabutyl titanate dropwise into 20 mL of anhydrous ethanol, then add 30 mL of 0.1 mol L -1 Nitric acid solution (acidified to control the hydrolysis rate of tetrabutyl ester and inhibit the formation of precipitation to form a stable sol); then 2g of biochar was added to the system and the system was vigorously stirred for 1h;

[0108] 2.2. Heat the system in a constant temperature water bath at 78°C for 3.2 hours. Wash the treated samples three times with deionized water and dry at 80°C.

[0109] 2.3. Then, the sample was placed in a tube furnace, the heating rate was set to 5°C / min, and calcined at 300°C for 3h. After the sample was cooled naturally, it was taken out and ground through a 100-mesh sieve to obtain a modified TiO2 photocatalyst.

[0110] Example 7

[0111] Step 1: Preparation of biochar from wastewater flocculants

[0112] 1.1. Take 1L of livestock and poultry wastewater and filter out impurities with gauze;

[0113] 1.2. Add 100 mL of 12 g / L polyferric sulfate solution (SPFS) and 300 mL of 0.9 g / L cationic polyacrylamide (CPAM) to 1 L of wastewater to obtain a mixed solution.

[0114] 1.3. Stir the mixed solution magnetically for 1 h (600 r min -1 ), stirring is to make the added flocculant fully mixed and dispersed in the water, and promote the rapid aggregation of suspended matter in the water to form larger particles), after the stirring is completed, let it stand until the solid and liquid are separated, and then the upper solid, i.e., flocculent, is removed;

[0115] 1.4. Dry the taken out flocculants at 80℃, crush them, and grind them through a 100-mesh sieve;

[0116] 1.5. Spread the obtained powder in a corundum crucible, place it in a tubular resistance furnace, set the heating rate to 5°C / min under nitrogen protection, and calcine at 800°C for 2h. After the calcination is completed, wait for the product to cool naturally to room temperature and then take it out;

[0117] 1.6. The product was treated with 1 mol L -1 The residue was washed with HCl and then with deionized water until the filtrate was neutral, and then dried in an oven at 80 °C to obtain biochar.

[0118] Step 2: Preparation of modified TiO2 photocatalyst using biochar and tetrabutyl titanate

[0119] 2.1. Slowly add 20 mL of tetrabutyl titanate dropwise into 20 mL of anhydrous ethanol, then add 30 mL of 0.1 mol L -1 Nitric acid solution (acidified to control the hydrolysis rate of tetrabutyl ester and inhibit the formation of precipitation to form a stable sol); then 2g of biochar was added to the system and the system was vigorously stirred for 1h;

[0120] 2.2. Heat the system in a constant temperature water bath at 75°C for 3.5 hours. Wash the treated samples three times with deionized water and dry at 80°C.

[0121] 2.3. Then, the sample was placed in a tube furnace, the heating rate was set to 5°C / min, and calcined at 600°C for 3h. After the sample was cooled naturally, it was taken out and ground through a 100-mesh sieve to obtain a modified TiO2 photocatalyst.

[0122] Comparative Example 1

[0123] Slowly add 15 mL of tetrabutyl titanate dropwise into 20 mL of anhydrous ethanol, then add 30 mL of 0.1 mol / L -1 nitric acid solution (acidified to control the hydrolysis rate of tetrabutyl ester and inhibit the formation of precipitation to form a stable sol); the system was vigorously stirred for 1 hour;

[0124] 2.2. Heat the system in a constant temperature water bath at 80°C for 3 hours. Wash the treated samples three times with deionized water and dry at 80°C.

[0125] 2.3. Then, the sample was placed in a tube furnace, the heating rate was set to 5°C / min, and calcined at 450°C for 3h. After it cooled down naturally, the sample was taken out and ground through a 100-mesh sieve to obtain a modified TiO2 photocatalyst, which was recorded as F0 / TiO2.

[0126] Figure 1 The SEM image of F2 / TiO2 prepared in Example 4 is shown in FIG. Figure 1 It can be seen that the prepared composite material is a sphere of uniform size.

[0127] Figure 2 The photocatalytic materials F0 / TiO2 and F 2 / XRD image of TiO2, using XRD to analyze the sample, Figure 2 It can be seen that the diffraction peaks of F0 / TiO2 appear at 27.43°, 39.19°, and 54.31°, which correspond to the (110), (200), and (211) crystal planes of TiO2, respectively. By comparing the standard PDF card of TiO2 (PDF#71-0650), it can be seen that the synthesized material is TiO2. At the same time, other diffraction peaks were found on F2 / TiO2, indicating that new substances were generated on the synthesized composite material.

[0128] Application Example 1 Photocatalytic material degrades antibiotics under simulated sunlight

[0129] The modified TiO2 photocatalyst prepared in Examples 1-5 was used to degrade the antibiotic sulfamethoxazole (SMZ) under simulated sunlight (350W xenon lamp light source, equipped with a 290nm filter), and TiO2 purchased from Sinopharm Group was used as a control group. The antibiotic sulfamethoxazole was treated with light without adding a catalyst as a blank group, recorded as CK.

[0130] The concentration of sulfamethoxazole was 10 mg / L, and the amount of modified TiO2 photocatalyst added was 2 g / L. Figure 3 .

[0131] The degradation rates of sulfamethoxazole in the control group and Examples 1-5 were 67.69%, 74.79%, 75.76%, 78.95%, 85.32% and 79.77% respectively. When the amount of biochar added was 2g, the prepared material had the best effect, with a removal rate of sulfamethoxazole of 85.32%, which was 102.32% higher than that of CK and 26.05% higher than that of the purchased TiO2.

[0132] The present invention shows that the flocculant is calcined in a tube furnace for 2h (900℃, 5℃min -1 , N2 protection) to obtain biochar, add 2g of biochar to 15mL of butyl titanate, and continue to heat the obtained gel in a tube furnace (450℃, 3h, 5℃min -1 ), the modified TiO2 photocatalyst prepared under this condition has the best photocatalytic efficiency.

[0133] The concentration of sulfamethoxazole was 10 mg / L, and the addition amounts of the modified TiO2 photocatalyst prepared in Example 4 were 1 g / L, 2 g / L, 4 g / L, and 6 g / L, respectively. Figure 4 ,It can be seen that with the increase of modified TiO2 photocatalyst, when the addition amount is 4g / L and 6g / L, the removal rate of sulfamethoxazole is equivalent. Considering the following tests comprehensively, 4g / L is selected.

[0134] When the addition amount of the modified TiO2 photocatalyst prepared in Example 4 was 4 g / L, the concentration of sulfamethoxazole was 5 mg / L, 10 mg / L, 15 mg / L, and 20 mg / L, respectively, all of which were above 70%. Figure 5 It can be seen that the modified TiO2 photocatalyst prepared by the present invention has a higher photocatalytic efficiency.

[0135] The amount of modified TiO2 photocatalyst prepared in Example 4 is 4 g / L, the concentration of sulfamethoxazole is 10 mg / L, and the pH of the antibiotic solution is adjusted by 1 mmol / L hydrochloric acid or 1 mmol / L sodium hydroxide. Figure 6 It can be seen that when the pH range is 3.0-5.0, sulfamethoxazole has a better removal rate.

[0136] Application Example 2 Photocatalytic material degrades actual wastewater under simulated sunlight

[0137] 100 mL of polyferric sulfate (SPFS, 5 g L) was added to 1 L of livestock and poultry wastewater. -1) and 300 mL cationic polyacrylamide (CPAM, 0.6 g L -1 ). After solid-liquid separation, the liquid was taken to measure the relevant water quality indicators, see Table 2.

[0138] Table 2 Related water quality indicators of wastewater before and after flocculation

[0139]

[0140] The wastewater after flocculation treatment and the wastewater diluted 2, 10, and 20 times were used for photocatalytic experiments. The modified TiO2 photocatalyst prepared in Example 4 was used to explore the photocatalytic removal effect of the main pollutants in the wastewater.

[0141] Reaction conditions: Catalyst dosage: 4 g L -1 ; Wastewater volume: 50mL; Reaction time: 2h; Reaction temperature: 25℃; Light source: 350W xenon lamp + 290nm filter.

[0142] The COD, TOC, TN, TP and turbidity of the degraded wastewater (undiluted) are: 572 mg L -1 、72.92mg L -1 、321.7mg L -1 、16.75mg L -1 , 71.17NTU.

[0143] The COD, TOC, TN, TP and turbidity of the degraded wastewater (diluted 2 times) are: 234 mg L -1 、28.77mg L -1 、131.9mg L -1 、7.74mg L -1 、29.5NTU.

[0144] The COD, TOC, TN, TP and turbidity of the wastewater (diluted 10 times) after degradation are: 36 mg L -1 , 4.3mg L -1 、19.66mg L -1 , 0.97mg L -1 、4.16NTU.

[0145] The COD, TOC, TN, TP and turbidity of the degraded wastewater (diluted 20 times) are: 14 mg L -1 , 1.3mg L -1 , 6.1mg L -1 , 0.33mg L -1 , 1.67NTU.

[0146] Degradation rate Figure 7As the wastewater was diluted and the initial pollutant concentration decreased, the degradation rate of pollutants in the wastewater by the photocatalyst gradually increased. COD increased from 86.42 to 93.35%; the degradation rate of total phosphorus increased the most, from 37.96% to 75.56%.

[0147] Application Example 3 Photocatalytic material degrades livestock and poultry breeding wastewater under actual sunlight

[0148] Take the livestock and poultry breeding wastewater after flocculation treatment, add TiO2 purchased by Sinopharm Group and F2 / TiO2 prepared by the present invention, respectively, and place it outdoors in a place with sufficient light for photocatalytic degradation. Samples are taken on the 1st, 2nd, 3rd, 4th, 5th, 10th, and 15th days to measure the degradation of COD in the breeding wastewater. And the blank group without adding catalyst is recorded as CK. It should be noted that the flocculation treatment steps of livestock and poultry breeding wastewater in this application example are the same as those in application example 2.

[0149] Reaction conditions: livestock and poultry wastewater: 200 mL; catalyst dosage: 4 g L -1 ; Reaction time: 15 days; Reaction temperature: 25°C; Light source: natural sunlight. Results are shown in Figure 7 .

[0150] Figure 8 In the experiment, under actual light, the degradation rates of COD in livestock and poultry wastewater by TiO2 and F2 / TiO2 were 55.45% and 83.31% respectively. The degradation rate of COD by F2 / TiO2 was 1.59 times that of CK and 1.50 times that of TiO2.

[0151] Fig. 9 is the contribution rate of free radicals in the photocatalytic removal of organic matter by F2 / TiO2. After adding IPA, EDTA-2Na and p-BQ, the degradation rates of SMZ are 9.84%, 12.68% and 56.97% respectively. Therefore, in the photocatalytic process, water molecules or hydroxyl radicals are replaced by photogenerated holes (h + ) is the main free radical that causes SMZ degradation. In addition, the dissolved oxygen in the water receives ·O 2- It also plays a certain role.

[0152] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0153] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a modified TiO2 photocatalyst, characterized in that: The following steps are involved: Adding a polyferric sulfate solution and a polyacrylamide solution to wastewater to obtain a mixed solution, mixing the mixed solution evenly, and then standing the mixed solution until solid-liquid separation to obtain floccules; After the flocculent is dried and crushed, it is calcined once at 600-900°C in a nitrogen atmosphere, and after the calcination is completed, it is washed and dried to obtain biochar; Anhydrous ethanol is used as solvent, tetrabutyl titanate is used as titanium source, nitric acid is used as inhibitor, biochar is added and stirred evenly, and then stirred to react to obtain the product; The product is subjected to secondary calcination at 300-600° C. to obtain a modified TiO2 photocatalyst.

2. The method for preparing a modified TiO2 photocatalyst according to claim 1, characterized in that: The wastewater is wastewater generated by flushing feces and urine in livestock and poultry breeding; the volume ratio of the wastewater to the polyferric sulfate solution is 1:0.1, and the concentration of the polyferric sulfate solution is 2-12 g / L; The volume ratio of wastewater to polyacrylamide solution is 1:0.3, and the concentration of polyacrylamide solution is 0.1-0.9 g / L.

3. The method for preparing a modified TiO2 photocatalyst according to claim 1, characterized in that: The primary calcination condition is calcination at 600-900°C for 2h, with a heating rate of 5°C / min.

4. The method for preparing a modified TiO2 photocatalyst according to claim 1, characterized in that: The volume ratio of tetrabutyl titanate, anhydrous ethanol and nitric acid is 1-2:2:3; the concentration of nitric acid is 0.1 mol / L.

5. The method for preparing a modified TiO2 photocatalyst according to claim 1, characterized in that: The ratio of tetrabutyl titanate to biochar is 15-20 ml: 0.1-4 g; the stirring reaction is carried out at 75-80° C. for 3-3.5 hours.

6. The method for preparing a modified TiO2 photocatalyst according to claim 1, characterized in that: The secondary calcination conditions are calcination at 300-600°C for 3h and a heating rate of 5°C / min.

7. A modified TiO2 photocatalyst prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the modified TiO2 photocatalyst according to claim 7 in degrading wastewater, characterized in that: The wastewater is antibiotic wastewater or livestock and poultry breeding wastewater.

9. The use of a modified TiO2 photocatalyst in degrading wastewater according to claim 8, wherein the livestock and poultry wastewater is flocculated, and then the modified TiO2 photocatalyst is added and degraded under sunlight, and the addition amount of the modified TiO2 photocatalyst is 1-6 g / L.

10. The use of a modified TiO2 photocatalyst in degrading wastewater according to claim 8, characterized in that: The antibiotic is sulfamethoxazole; The modified TiO2 photocatalyst is added to the antibiotic wastewater and degraded under sunlight. The concentration of the antibiotic in the antibiotic wastewater is 10-50 mg / L, and the added amount of the modified TiO2 photocatalyst is 1-6 g / L.

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