Modified titanium dioxide photocatalyst from corn stalks, method of preparation and use

Abstract

The application discloses a corn straw modified titanium dioxide photocatalyst, a preparation method and application thereof. The preparation method comprises the following steps: (1) crushing corn straw, calcining the crushed corn straw, and obtaining calcined corn straw; (2) mixing the calcined corn straw, ethanol and water to obtain a mixed solution A; mixing tetrabutyl titanate, glacial acetic acid and ethanol to obtain a mixed solution B; adding the mixed solution A into the mixed solution B to react, and then standing to obtain a gel; wherein the mass ratio of the corn straw to the tetrabutyl titanate is 0.05-0.15:100; wherein the mass of the tetrabutyl titanate is calculated based on the mass of completely formed titanium dioxide; (3) drying the gel to obtain a dry gel; and calcining the dry gel to obtain the corn straw modified titanium dioxide photocatalyst. The modified titanium dioxide photocatalyst can be used for degrading organic dye sewage, and can effectively degrade methyl violet in particular.

Description

Technical Field

[0001] This invention relates to a corn stalk modified titanium dioxide photocatalyst, its preparation method, and its application. Background Technology

[0002] Crystal violet, malachite green, methyl violet, and other triarylmethane dyes are widely used in paper, leather, bio-dyeing, and plastic coloring. Wastewater from these dyes is characterized by high color and salinity, and possesses a persistent aromatic structure, which not only damages aquatic ecosystems but also potentially harms human health and the environment through the food chain. Traditional wastewater treatment methods, such as physical adsorption (e.g., activated carbon), suffer from limited adsorption capacity and high regeneration costs; chemical coagulation has low removal rates for highly water-soluble dyes (only 20-50%) and generates large amounts of toxic sludge; biological treatment is inefficient due to the high biotoxicity of dyes, and its activity is inhibited by increased salinity; while advanced oxidation methods can effectively degrade dyes, they are costly to operate and pose a risk of secondary pollution.

[0003] Photocatalysis technology is simple to operate, low in cost, and environmentally friendly, producing no secondary pollution. It utilizes sunlight to generate ·OH and ·O2 on the surface of the photocatalyst. - Active free radicals degrade organic pollutants into CO2, H2O and inorganic salts.

[0004] Titanium dioxide exists in nature in three crystal forms: anatase, rutile, and brookite. Among them, anatase nanocrystals have high photoactivity at room temperature, but their band gap is 3.0–3.2 eV, meaning that only about 4% of ultraviolet light can excite the photocatalytic activity of titanium dioxide, resulting in low visible light utilization and limiting the practical application of titanium dioxide.

[0005] CN116212845A discloses an application of a titanium dioxide / Ulva prolifera charcoal composite. The prepared titanium dioxide / Ulva prolifera charcoal composite is used for the degradation of petroleum-based water pollutants.

[0006] CN117443367A discloses a titanium dioxide / wheat straw titanium composite photocatalytic material for treating heavy metal wastewater and the recycling of the photocatalyst. The photocatalyst reduces hexavalent chromium in the wastewater through adsorption-desorption.

[0007] CN118949966A discloses a calcium / biochar / titanium dioxide composite photocatalytic material for the photocatalytic degradation of ammonia nitrogen wastewater. Clam shell powder was used as the calcium source, and calcium-doped biochar was prepared by combining it with sludge from a sweet potato plant. This biochar was then combined with TiO2 to obtain the calcium / biochar / titanium dioxide composite photocatalytic material, which achieved a maximum ammonia nitrogen removal rate of 81.37% in the wastewater.

[0008] None of the above literature addresses the application of composite photocatalytic materials in the degradation of triarylmethane dyes in wastewater.

[0009] CN106693947A discloses a calcium-doped titanium dioxide nanofiber photocatalytic material for the photocatalytic degradation of triarylmethane dyes. Calcium acetate is used as the calcium source, and a sol solution is formed through electrospinning followed by high-temperature carbonization to obtain the photocatalytic material, which then undergoes photocatalytic degradation under ultraviolet light irradiation. However, using calcium acetate as the calcium source can easily cause secondary environmental pollution, and the preparation process is relatively complex.

[0010] CN106890645A discloses a perovskite oxide-doped titanium dioxide photocatalyst for the degradation of organic dyes, especially triarylmethane dyes. While using perovskite oxide as the main component of the photocatalyst results in a high degradation rate, the high cost of perovskite oxide hinders its widespread application. Summary of the Invention

[0011] In view of this, one object of the present invention is to provide a method for preparing a corn stalk modified titanium dioxide photocatalyst. The corn stalk modified titanium dioxide photocatalyst prepared by this method can be used to degrade organic dye wastewater, preferably for degrading triarylmethane organic dye wastewater, and exhibits particularly good photocatalytic degradation effect on methyl violet. Another object of the present invention is to provide a corn stalk modified titanium dioxide photocatalyst prepared according to the method described above. A further object of the present invention is to provide an application of the corn stalk modified titanium dioxide photocatalyst described above.

[0012] The present invention achieves the above objectives through the following technical solutions.

[0013] On one hand, the present invention provides a method for preparing a corn stalk modified titanium dioxide photocatalyst, comprising the following steps:

[0014] (1) Crush the corn stalks, and calcine the crushed corn stalks to obtain calcined corn stalks.

[0015] (2) The calcined corn stalks, ethanol and water are mixed to obtain mixture A; tetrabutyl titanate, glacial acetic acid and ethanol are mixed to obtain mixture B; mixture A is added to mixture B to react, and then allowed to stand to obtain a gel; wherein the mass ratio of corn stalks to tetrabutyl titanate is 0.05 to 0.15:100; wherein the mass of tetrabutyl titanate is calculated based on the mass of the fully formed titanium dioxide;

[0016] (3) Dry the gel to obtain a dry gel; calcine the dry gel to obtain a corn stalk modified titanium dioxide photocatalyst.

[0017] According to the preparation method of the present invention, preferably, the mass ratio of calcined corn stalks to tetrabutyl titanate is 0.07 to 0.12:100.

[0018] According to the preparation method of the present invention, preferably, in step (1), the calcination temperature is 450-550℃ and the calcination time is 1.5-3h.

[0019] According to the preparation method of the present invention, preferably, in step (2), the mass concentration of calcined corn stalks in mixture A is 0.01-0.05 wt%; and the ethanol is anhydrous ethanol.

[0020] According to the preparation method of the present invention, preferably, in step (2), the concentration of tetrabutyl titanate in mixture B is 0.05-1.5 mol / L, and the molar ratio of glacial acetic acid to tetrabutyl titanate is 5-20:1.

[0021] According to the preparation method of the present invention, preferably, in step (3), the drying temperature is 60-120°C and the drying time is 1-6h.

[0022] According to the preparation method of the present invention, preferably, in step (3), the calcination temperature is 400-600℃ and the calcination time is 2-12h.

[0023] On the other hand, the present invention provides a corn stalk modified titanium dioxide photocatalyst prepared by the preparation method described above.

[0024] In another aspect, the present invention provides an application of the corn stalk modified titanium dioxide photocatalyst as described above in the degradation and treatment of organic dye wastewater.

[0025] According to the application described in this invention, preferably, the organic dye in the organic dye wastewater is methyl violet.

[0026] The corn stalk modified titanium dioxide photocatalyst prepared by the method of the present invention can be used to degrade and treat triarylmethane organic dye wastewater, especially showing good photocatalytic degradation effect on methyl violet, with a photocatalytic degradation rate of up to 98.20%. Attached Figure Description

[0027] Figure 1 Scanning electron microscope image of a titanium dioxide photocatalyst modified from corn stalks.

[0028] Figure 2 X-ray diffraction pattern of the corn stalk modified titanium dioxide photocatalyst.

[0029] Figure 3 The UV-Vis diffuse reflectance spectra of titanium dioxide photocatalyst and corn stalk modified titanium dioxide photocatalyst are shown. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0031] <Preparation Method of Corn Stalk Modified Titanium Dioxide Photocatalyst>

[0032] The preparation method of a corn stalk modified titanium dioxide photocatalyst provided by the present invention includes the following steps: (1) corn stalk pretreatment step; (2) reaction to form gel step; (3) drying and calcination step.

[0033] This invention employs a sol-gel method, using tetrabutyl titanate as a precursor and glacial acetic acid as an inhibitor, to hydrolyze and condense corn stalks in the presence of calcined corn stalks to form a gel. This gel is then dried and calcined to crystallize, ultimately yielding a corn stalk-modified titanium dioxide photocatalyst. Extensive research and experiments have revealed that controlling the mass ratio of corn stalks to titanium dioxide is crucial; only by maintaining this ratio within a specific range can a modified titanium dioxide photocatalyst exhibit good catalytic degradation effects on triarylmethane organic dyes be obtained. Furthermore, the preparation method of this invention is simple to operate and low in cost. A detailed description follows.

[0034] Corn stalk pretreatment steps

[0035] 5-10g of corn stalks are crushed into corn stalk fragments with an average particle size of 1-10mm. The crushed corn stalk fragments are then calcined to obtain calcined corn stalks.

[0036] In this invention, corn stalks can be pulverized using a pulverizer at a speed of 15,000–50,000 rpm for 15–30 minutes to obtain corn stalk fragments with an average particle size of 1–10 mm. The corn stalk fragments are then subjected to calcination and carbonization treatment to obtain calcined corn stalks. The pulverizing speed of the pulverizer can be 15,000–50,000 rpm, preferably 25,000–40,000 rpm, more preferably 28,000–33,000 rpm. The pulverizing time can be 15–30 minutes, preferably 20–25 minutes. The calcination temperature can be 450–550℃, preferably 470–530℃, more preferably 490–515℃, and even more preferably 495–505℃. The calcination time can be 1.5–3 hours, preferably 1.5–2.5 hours, more preferably 1.5–2 hours. According to a specific embodiment of the invention, the calcination temperature is 500℃ and the calcination time is 2 hours. This invention discovers that calcination temperature also has a certain impact on the catalytic performance of the obtained corn stalk modified titanium dioxide photocatalyst. Only by controlling the calcination temperature within the above range can it be more beneficial to obtain a modified titanium dioxide photocatalyst with better catalytic degradation effect.

[0037] Reaction to form gel step

[0038] Calcined corn stalks, ethanol, and water were mixed to obtain mixture A; tetrabutyl titanate, glacial acetic acid, and ethanol were mixed to obtain mixture B; mixture A was added to mixture B to react, and then allowed to stand to obtain a gel. The mass ratio of calcined corn stalks to tetrabutyl titanate was 0.05–0.15:100; the mass of tetrabutyl titanate was calculated based on the mass of the fully formed titanium dioxide.

[0039] In this invention, the mass concentration of calcined corn stalks in mixture A is 0.01–0.05 wt%, preferably 0.01–0.35 wt%, more preferably 0.01–0.15 wt%; the ethanol is anhydrous ethanol, and the water can be distilled water or purified water. The volume ratio of the anhydrous ethanol to water mixture is 0.1–1:1 L, preferably 0.3–0.8:1 L, more preferably 0.5–0.8:1 L. According to a specific embodiment of this invention, the volume ratio of the anhydrous ethanol to water mixture is 0.7:1 L.

[0040] In this invention, the concentration of tetrabutyl titanate in mixture B can be 0.05–1.5 mol / L, preferably 0.2–1.1 mol / L, and more preferably 0.5–0.8 mol / L. The molar ratio of glacial acetic acid to tetrabutyl titanate is 5–20:1, preferably 5–15:1, and more preferably 6–10:1. According to a specific embodiment of the invention, the molar ratio of glacial acetic acid to tetrabutyl titanate is 7:1. Such an addition amount can provide a moderate hydrolysis rate for tetrabutyl titanate, slowing down the hydrolysis rate of tetrabutyl titanate to avoid the formation of titanium hydroxide precipitate.

[0041] In this invention, it is preferable to add mixture A to mixture B in batches for reaction, allow it to stand, and obtain a gel. The reaction can be carried out by stirring at 100–400 rpm for 1–3 hours, followed by standing for 12–48 hours to obtain the gel. The stirring speed is preferably 200–350 rpm, more preferably 250–300 rpm; the reaction time is preferably 1.5–2.5 hours, more preferably 1.5–2 hours; and the standing time is preferably 18–36 hours, more preferably 20–24 hours. According to a specific embodiment of the invention, mixture A is added to mixture B in batches, stirred at 280 rpm for 2 hours, and then allowed to stand for 24 hours to obtain a gel. These conditions ensure that the titanium dioxide obtained from the reaction of calcined corn stalks and tetrabutyl titanate is uniformly mixed, resulting in a gel with a homogeneous composition.

[0042] In this invention, the mass ratio of calcined corn stalks to tetrabutyl titanate can be 0.05–0.15:100, preferably 0.07–0.12:100, and more preferably 0.09–0.11:100; wherein the mass of tetrabutyl titanate is calculated based on the mass of fully formed titanium dioxide. According to a specific embodiment of this invention, the mass ratio of corn stalks to tetrabutyl titanate is 0.10:100.

[0043] Drying and calcination steps

[0044] The gel was dried to obtain a dry gel; the dry gel was calcined to obtain a corn stalk modified titanium dioxide photocatalyst.

[0045] In this invention, the gel can be dried using a forced-air drying oven or a vacuum drying oven to obtain a dry gel. The drying temperature can be 60–120°C, preferably 80–115°C, more preferably 95–105°C, and the drying time can be 1–6 hours, preferably 1.5–4.5 hours, more preferably 1.5–2.5 hours. According to a specific embodiment of the invention, the drying temperature is 100°C and the drying time is 2 hours.

[0046] The calcination temperature for the dry gel can be 400–600°C, preferably 450–550°C, and more preferably 450–520°C. The calcination time can be 2–12 h, preferably 4–8 h, and more preferably 5.5–7.5 h. According to a specific embodiment of the present invention, the calcination temperature for the dry gel is 500°C, and the calcination time is 6 h. Such a calcination temperature is more conducive to ensuring that the titanium dioxide crystals exist in the anatase crystal form.

[0047] <Corn stalk modified titanium dioxide photocatalyst>

[0048] The corn stalk-modified titanium dioxide photocatalyst of the present invention is obtained by the preparation method described above. The inventors believe that calcining corn stalks can yield a biomass carbon material with a porous structure, which possesses abundant active adsorption sites and a stable chemical structure. The calcined corn stalks are hydrolyzed and polycondensed with tetrabutyl titanate to obtain a gel, which, after calcination, transforms the modified titanium dioxide into anatase, thereby improving its catalytic degradation effect on triarylmethane organic dyes.

[0049] <Application of Corn Stalk Modified Titanium Dioxide Photocatalyst>

[0050] The present invention also provides an application of corn stalk modified titanium dioxide photocatalyst in the photocatalytic degradation of organic dye wastewater, preferably the photocatalytic degradation of triarylmethane organic dye wastewater, especially showing good photocatalytic degradation effect on methyl violet, with a photocatalytic degradation rate of up to 98.20% for methyl violet.

[0051] The testing method is described below:

[0052] Scanning electron microscopy (SEM) testing: First, conductive adhesive was applied to the sample tray of the SEM. The corn stalk modified titanium dioxide photocatalyst was ground into powder. Then, a small amount of the corn stalk modified titanium dioxide photocatalyst was adhered to the conductive adhesive. The sample surface was then sputtered with gold using an ion sputtering instrument. The morphology of the sample was then analyzed and tested using a scanning electron microscope. The scanning electron microscope used was a NOVA NANO 230 from FEI Ltd., USA.

[0053] X-ray diffraction (XRD) testing: The corn stalk modified titanium dioxide photocatalyst was analyzed by X-ray diffraction (XRD) using a TD-3000 X-ray diffractometer manufactured by Liaoning Dandong Tongda Instrument Factory, under room temperature conditions using Cu Kα rays (…). The scanning speed is 1° / min, the scanning range 2θ is 10°~70°, the tube current is 40mA, and the tube voltage is 40kV.

[0054] The following describes the sources of raw materials and the main instruments and equipment:

[0055] <Source of Raw Materials>

[0056] Corn stalks, sourced from Nanpi County, Cangzhou City, Hebei Province.

[0057] Glacial acetic acid (analytical grade), Tianjin Bohua Chemical Reagent Co., Ltd.

[0058] Anhydrous ethanol (analytical grade), Tianjin Bohua Chemical Reagent Co., Ltd.;

[0059] Tetrabutyl titanate (analytical grade), Tianjin Chemical Reagent Supply and Marketing Company;

[0060] Methyl violet (analytical grade), CAS No.: 8004-87-3, Shanghai Mairui Biochemical Technology Co., Ltd.

[0061] <Main Instruments and Equipment>

[0062] Xenon lamp light source, model CEL-HXF300, Beijing Zhongjiao Jinyuan Technology Co., Ltd.;

[0063] Ultraviolet spectrophotometer, model UV-1100, Shanghai Meixi Instrument Co., Ltd.;

[0064] Electric thermostatic drying oven, model DHG-9070A, manufactured by Tianjin Xingke Technology Co., Ltd.

[0065] Microwave muffle oven, model UP-700, Beijing Xianghu Technology Development Co., Ltd.

[0066] Example 1

[0067] 7g of corn stalks were crushed in a pulverizer. The average particle size of the crushed corn stalks was 5mm. The crushed corn stalks were then placed in a muffle furnace and calcined at 500℃ for 2 hours to obtain calcined corn stalks.

[0068] 2.35 mg of calcined corn stalks were added to a mixture of 7 mL of anhydrous ethanol and 10 mL of distilled water (volume ratio of anhydrous ethanol to distilled water: 0.7:1) to obtain mixture A. 10 mL of tetrabutyl titanate was added to a mixture of 12 mL of glacial acetic acid and 30 mL of anhydrous ethanol to obtain mixture B. Mixture A was added to mixture B, and the mixture was stirred for 2 hours and allowed to stand for 24 hours to obtain a gel. The mass ratio of corn stalks to tetrabutyl titanate was 0.1:100; the mass of tetrabutyl titanate was calculated based on the mass of the fully formed titanium dioxide.

[0069] The gel was dried at 100℃ for 2 hours to obtain a dry gel. The dry gel was then calcined at 500℃ for 6 hours to obtain a corn stalk modified titanium dioxide photocatalyst.

[0070] The SEM results of the obtained corn stalk modified titanium dioxide photocatalyst are as follows: Figure 1 As shown. The XRD results of the corn stalk modified titanium dioxide photocatalyst are shown below. Figure 2 As shown.

[0071] Depend on Figure 1 It can be seen that the obtained corn stalk modified titanium dioxide photocatalyst consists of spherical particles with a particle size of 20-30 nm.

[0072] Depend on Figure 2 It can be seen that the 2θ values ​​of the corn stalk modified titanium dioxide photocatalyst are 26.1°, 48.7°, 54.9° and 61.6°, corresponding to anatase titanium dioxide crystal planes (101), (200), (211) and (213). Therefore, it can be seen that the titanium dioxide in the corn stalk modified titanium dioxide photocatalyst is anatase.

[0073] Example 2

[0074] The only difference from Example 1 is that the mass ratio of calcined corn stalks to tetrabutyl titanate is 0.05:100; wherein the mass of tetrabutyl titanate is calculated based on the mass of fully formed titanium dioxide.

[0075] Example 3

[0076] The only difference from Example 1 is that the mass ratio of calcined corn stalks to tetrabutyl titanate is 0.15:100; wherein the mass of tetrabutyl titanate is calculated based on the mass of fully formed titanium dioxide.

[0077] Comparative Example 1

[0078] The only difference from Example 1 is that the calcined corn stalks are omitted.

[0079] Comparative Example 2

[0080] The only difference from Example 1 is that the mass ratio of calcined corn stalks to tetrabutyl titanate is 0.20:100; wherein the mass of tetrabutyl titanate is calculated based on the mass of fully formed titanium dioxide.

[0081] Comparative Example 3

[0082] The only difference from Example 1 is that the mass ratio of calcined corn stalks to tetrabutyl titanate is 0.25:100; wherein the mass of tetrabutyl titanate is calculated based on the mass of fully formed titanium dioxide.

[0083] Comparative Examples 4-6

[0084] The only difference from Example 1 is that the calcination temperatures of the dry gel were 400°C, 450°C, and 600°C, respectively.

[0085] Experimental Example

[0086] 1. The products obtained in Examples 1 to 3 were subjected to catalytic performance testing.

[0087] 40 mg of the corn stalk-modified titanium dioxide photocatalyst prepared in Examples 1, 2, and 3 were added to a 10 mg / L methyl violet dye solution and subjected to a dark reaction for 20 minutes. The solutions were then irradiated under a xenon lamp (wavelength 300 nm–2500 nm) for 0–120 minutes. Samples were taken every 10 minutes, filtered, and the absorbance of the clear solution was measured. The maximum absorption wavelength of methyl violet was 584 nm. The photocatalytic degradation rate was calculated using the formula: Photocatalytic degradation rate (%) = (Initial solution absorbance - Post-degradation solution absorbance) / Initial solution absorbance × 100%.

[0088] Table 1 shows the photocatalytic degradation rate of methyl violet by corn straw-modified titanium dioxide photocatalyst under different light exposure times.

[0089] Table 1

[0090]

[0091] Table 1 shows that the photocatalytic degradation rate of methyl violet reached its maximum when the illumination time reached 90 min, and remained basically unchanged with the extension of time. When the mass ratio of corn stalk to tetrabutyl titanate was 0.1:100, the corn stalk-modified titanium dioxide photocatalyst exhibited the highest photocatalytic degradation rate of methyl violet.

[0092] 2. The catalytic performance of the products obtained in Example 1 and Comparative Examples 1 to 3 was tested.

[0093] 40 mg of the corn stalk-modified titanium dioxide photocatalyst prepared in Examples 1 and 1 to 3 were added to a 10 mg / L methyl violet dye solution and subjected to a dark reaction for 20 minutes, followed by irradiation under a xenon lamp for 90 minutes. Samples were taken every 10 minutes, filtered, and the absorbance of the clear solution was measured. The maximum absorption wavelength of methyl violet was 584 nm. The degradation rate was calculated according to the formula described above. The photocatalytic degradation rates of methyl violet by different photocatalysts are shown in Table 2.

[0094] Table 2

[0095] mass ratio 0 0.10:100 0.20:100 0.25:100 Photocatalytic degradation rate / % 56.33 98.20 90.90 86.45

[0096] A comparison of Tables 1 and 2 shows that undoped titanium dioxide exhibits poor photocatalytic performance. However, an excessively high mass ratio (i.e., a large amount of calcined corn stalks) may block the contact between methyl violet and the modified titanium dioxide photocatalyst, thus reducing the catalytic performance.

[0097] 3. The catalytic performance of the products obtained in Comparative Examples 4 to 6 and Example 1 was tested.

[0098] 30 mg of the corn stalk-modified titanium dioxide photocatalyst prepared in Comparative Examples 4-6 and Example 1 were added to a 10 mg / L methyl violet dye solution and subjected to a dark reaction for 20 minutes, followed by irradiation under a xenon lamp for 90 minutes. Samples were taken every 10 minutes, filtered, and the absorbance of the clear solution was measured. The maximum absorption wavelength of methyl violet was 584 nm. The photocatalytic degradation rate was calculated according to the formula described above. The results of the photocatalytic degradation rate of methyl violet by the corn stalk-modified titanium dioxide photocatalyst at different calcination temperatures are shown in Table 3.

[0099] Table 3

[0100] Calcination temperature / °C 400 450 500 600 Photocatalytic degradation rate / % 55.14 61.41 71.63 52.55

[0101] As shown in Table 3, with increasing calcination temperature, the photocatalytic degradation of methyl violet by the corn stalk-modified titanium dioxide photocatalyst first increases and then decreases, reaching its highest rate at 500℃. At this temperature, the titanium dioxide in the corn stalk-modified titanium dioxide photocatalyst is anatase. When the calcination temperature exceeds 500℃, the titanium dioxide transforms from anatase to rutile.

[0102] 4. Effect of the dosage of corn stalk modified titanium dioxide photocatalyst on catalytic efficiency

[0103] A certain mass of the corn stalk-modified titanium dioxide photocatalyst prepared in Example 1 and Comparative Example 1 was weighed and added to 100 mL of a 10 mg / L methyl violet dye solution. A dark reaction was carried out for 20 min, followed by degradation under a xenon lamp as the light source for 90 min. Samples were taken every 10 min, the solution was filtered, and the absorbance of the clear liquid was measured. The photocatalytic degradation rate was calculated using the formula described above. The masses of corn stalk-modified titanium dioxide photocatalyst added were 0 mg, 20 mg, 30 mg, 40 mg, 50 mg, and 60 mg, respectively. The results of the degradation of the corn stalk-modified titanium dioxide photocatalyst in methyl violet solution for 90 min are shown in Table 4.

[0104] Table 4

[0105] Photocatalyst dosage / mg 0 20 30 40 50 60 Photocatalytic degradation rate / % 56.33 58.89 71.63 98.20 80.82 62.77

[0106] As shown in Table 4, the corn stalk-modified titanium dioxide photocatalyst of the present invention significantly improves the photocatalytic degradation rate of methyl violet solution. Furthermore, with the increase of photocatalyst dosage, the photocatalytic degradation rate of methyl violet first increases and then decreases. The highest photocatalytic degradation rate of methyl violet is achieved when the dosage of corn stalk-modified titanium dioxide photocatalyst is 40 mg. However, as the dosage of corn stalk-modified titanium dioxide photocatalyst continues to increase, the photocatalytic degradation rate of methyl violet gradually decreases. This may be because excessive photocatalyst can prevent light from passing through the solution, thus affecting light absorption.

[0107] This invention is not limited to the above-described embodiments. Any modifications, improvements, or substitutions that can be conceived by those skilled in the art without departing from the essential content of this invention fall within the scope of this invention.

Claims

1. A method for preparing a corn stalk modified titanium dioxide photocatalyst, characterized in that, Includes the following steps: (1) Crush the corn stalks, and calcine the crushed corn stalks to obtain calcined corn stalks; (2) Mix calcined corn stalks, ethanol and water to obtain mixture A; mix tetrabutyl titanate, glacial acetic acid and ethanol to obtain mixture B; add mixture A to mixture B to react, and then let stand to obtain gel; wherein, the mass ratio of calcined corn stalks to tetrabutyl titanate is 0.07 to 0.11:100; wherein, the mass of tetrabutyl titanate is calculated based on the mass of fully formed titanium dioxide; (3) Dry the gel to obtain a dry gel; calcine the dry gel to obtain corn straw modified titanium dioxide photocatalyst; wherein the calcination temperature is 500℃ and the calcination time is 2 to 12h.

2. The preparation method according to claim 1, characterized in that, In step (1), the calcination temperature is 450-550℃ and the calcination time is 1.5-3h.

3. The preparation method according to claim 1, characterized in that, In step (2), the mass concentration of calcined corn stalks in mixture A is 0.01-0.05 wt%; the ethanol is anhydrous ethanol.

4. The preparation method according to claim 1, characterized in that, In step (2), the concentration of tetrabutyl titanate in mixture B is 0.05-1.5 mol / L, and the molar ratio of glacial acetic acid to tetrabutyl titanate is 5-20:

1.

5. The preparation method according to claim 1, characterized in that, In step (3), the drying temperature is 60-120℃ and the drying time is 1-6h.

6. A corn stalk modified titanium dioxide photocatalyst prepared by the preparation method according to any one of claims 1 to 5.

7. The application of the corn stalk modified titanium dioxide photocatalyst according to claim 6 in the degradation and treatment of methyl violet wastewater.

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