A method for preparing an ordered porous catalytic material of carbonized hemp rod template carbon loaded TiO2

Abstract

The application discloses a preparation method of carbonized hemp rod template carbon loaded TiO2 ordered porous catalytic material, and relates to the technical field of photocatalysis. The method comprises the following steps: pretreating a hemp rod template; preparing TiO2 by a sol-gel method; precursor impregnation; drying and sintering. The application utilizes the natural hollow and ordered mesoporous structure of the hemp rod to load TiO2, thereby obtaining a kind of vacuum carbonized hemp rod template carbon loaded TiO2 ordered porous catalytic material. The application utilizes the synergistic effect of nano TiO2 and the natural, three-dimensional ordered connected structure and large specific surface area carrier, increases the TiO2 photocatalytic reaction substance concentration, improves the photocatalytic efficiency, is beneficial to the full contact with the purified substances and the material exchange in the catalytic reaction process, and achieves the purpose of efficient catalytic purification.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of titanium dioxide photocatalysis, and particularly relates to a preparation method of carbonized hemp rod template carbon loaded TiO2 ordered porous catalytic material, which is applied to the environmental technical field of wastewater treatment. BACKGROUND

[0002] In recent ten years, with the theme of sustainable development, global environmental problems have attracted more and more attention, and environmental pollution control and management are still major problems faced by human society and urgently to be solved. TiO2 can effectively degrade organic matters in wastewater into H2O, CO2, SO4 2- , PO4 3- , NO3 - , halogen ions and other inorganic small molecules, achieving the purpose of complete inorganicization; the hemp rod is naturally hollow and has rich mesoporous structure, and has excellent adsorption performance after carbonization; the surface of the TiO2 photocatalyst is modified by the graphite-like molecules, so that the charges on the conjugated pi bond interact with the semiconductor band, unique electron transport characteristics are generated, the synergistic effect with the TiO2 photocatalyst is caused, and the TiO2 photocatalytic efficiency is improved.

[0003] Among many methods for preparing and modifying TiO2, researchers at home and abroad use various natural crops as adsorbents to load TiO2 to treat industrial dye wastewater, such as using rice husk, Chinese fir, coconut shell, poplar, sugarcane residue and bamboo to prepare catalyst carriers; at present, the hemp rod is less researched, and is generally used as fuel, which not only has low economic benefits but also pollutes the environment; recycling and treating the hemp rod not only has environmental benefits, but also can reduce the economic cost of the hemp fiber industry to some extent, and further expand the development of the hemp industry. SUMMARY

[0004] The application aims to provide a vacuum carbonized hemp rod template carbon loaded TiO2 ordered porous catalytic material, which solves the recycling of hemp rod and improves the efficiency of the catalyst, and specifically comprises the following steps:

[0005] (1) Hemp rod template pretreatment: the hemp rod is cut into a required shape, activated and treated by being immersed into a phosphoric acid solution, then dehydrated and soaked by using anhydrous ethanol, taken out, and washed by using deionized water; then carbonized under vacuum, cleaned by using an ultrasonic cleaner, taken out, and dried for standby use.

[0006] (2) Preparation of TiO2 by sol-gel method: selecting TiO2 precursor, solvent, hydrolysis inhibitor and deionized water, mixing uniformly, and completely hydrolyzing under a certain water bath temperature to obtain TiO2.

[0007] (3) Hemp rod template load TiO2: hemp rod template is immersed in TiO2 solution, and is taken out after drying and is placed in a dry and ventilated place. TiO2 solution is deposited on the hemp rod template by using a dropper, and is naturally hydrolyzed. The deposition times are recorded as OMPTA-X, X is the loading times, and then is placed in TiO2 solution and is aged. After being taken out and dried, the ordered porous catalytic material is obtained.

[0008] (4) Sintering: the loaded TiO2 is placed in a muffle furnace for sintering. The sintering conditions are as follows: the temperature rising rate is not greater than 10 ℃ / min, the sintering temperature is 400 ℃-600 ℃, the holding time is 30 min-60 min, and the ordered porous catalytic material is obtained after being taken out and cooled.

[0009] Preferably, the mass percentage concentration of the phosphoric acid solution in step (2) is 40-60%, the immersion time is 6-12 h, and the dehydration soaking time in the anhydrous ethanol solution is 1-2 h.

[0010] Preferably, the solvent in step (2) is a mixture of one or more of ethanol, propanol, glycerol, acetyl, methanol and butanol.

[0011] Preferably, the hydrolysis inhibitor in step (2) is a mixture of one or more of glacial acetic acid, glacial acetic acid, hydrochloric acid and nitric acid, and the aqueous solution is deionized water.

[0012] Preferably, the TiO2 precursor in step (2) is one of tetrabutyl titanate, n-tetrabutyl titanate, isopropyl titanate, TiCl4 and TiCl3.

[0013] Preferably, the volume ratio of the TiO2 precursor, the solvent, the deionized water and the hydrolysis inhibitor in step (2) is (7-8):(28-40):1.25:(1-8).

[0014] Preferably, after being uniformly mixed, the mixture is placed in a water bath at a temperature of 40-60 ℃ for complete hydrolysis.

[0015] Preferably, the ultrasonic-assisted immersion time in step (3) is 60 min-120 min, and the TiO2 solution is taken out after forming a gel.

[0016] The beneficial effects of the present application are as follows:

[0017] (1) By controlling the vacuum carbonization conditions, the natural and three-dimensional ordered connected structure of the hemp rod can be effectively maintained.

[0018] (2) The hemp stem carbon obtained by vacuum carbonization is directly used as a template to load titanium dioxide, avoiding the complicated process of preparing a template and removing the template of ordered porous catalytic materials, and thus ordered porous catalytic materials can be obtained in a short process.

[0019] (3) The ordered structure of hemp stem carbon obtained by vacuum carbonization is beneficial to the full contact and material exchange with the purified substances in the catalytic reaction process, so as to achieve the purpose of efficient catalytic purification.

[0020] (4) The titanium dioxide is loaded on the ordered structure carrier of hemp stem to realize the immobilization of active surface substances, prevent the aggregation or loss of particles, and produce the desired synergistic effect between the catalyst and its carrier. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 SEM image of the ordered porous catalytic material of a hemp stem template carbon loaded with TiO2 in Example 2;

[0022] Figure 2 XRD image of the ordered porous catalytic material of a hemp stem template carbon loaded with TiO2 in Example 3;

[0023] Figure 3 XRD image of the C / TiO2 composite powder photocatalyst in Example 4. DETAILED DESCRIPTION

[0024] The application will be further described in detail below in conjunction with specific embodiments, but the protection scope of the application is not limited to the content described.

[0025] In the experiment, a methylene blue (MB) solution prepared in advance was used to simulate a wastewater system to analyze the photocatalytic degradation and adsorption performance thereof; 0.1 g of the ordered porous catalytic material loaded with TiO2 was taken and irradiated under natural light for 2 h (09:00-11:00) with a wastewater solution with a mass concentration of 10 mg / L, the sample was taken out, marked and sealed for storage, the sample was centrifuged in a centrifuge (5000 r / min) for 5 min, and then the concentration of the wastewater solution was analyzed and tested by using an ultraviolet spectrophotometer.

[0026] Example 1

[0027] (1) The hemp stem was cut into a columnar shape with D: 30 and H: 20 (D is the diameter and H is the height), soaked in a phosphoric acid solution with a mass concentration of 40% for activation treatment for 10 h, then soaked in an ethanol solution for 4 h, and dried for standby use.

[0028] (2) The pretreated hemp stem was carbonized in a vacuum sintering furnace, the sintering temperature was 800℃, the sintering time was 100 min, the holding time was 60 min, and the vacuum degree reached 1×10 -2Pa, and take it out after cooling in the furnace.

[0029] (3) Preparation of TiO2 by sol-gel method; the reaction was carried out in a water bath at a constant temperature of 40°C, 7 mL of tetrabutyl titanate was added dropwise to 21 mL of anhydrous ethanol to prepare solution A, and magnetic stirring was applied for 20 min; 7 mL of anhydrous ethanol and 1.25 mL of deionized water were mixed, and 1 mL of HCL was added dropwise to adjust the pH value to 1 to prepare solution B; solution B was added to solution A, and stirring was continued for 2 h. The rotation speed was set to 500 r / min to obtain a mixed solution.

[0030] (4) Immerse the carbonized hemp stem in the mixed solution, place it in an ultrasonic cleaner for ultrasonic assisted immersion for 1 hour, take it out and place it in a dry and ventilated place to dry naturally, use a dropper to deposit the TiO2 solution on the carbonized hemp stem for natural hydrolysis, OMPTA-5 (X is the number of loading times), then place it in the TiO2 solution for aging, and take it out to dry.

[0031] (5) The carbonized hemp stem loaded with TiO2 was placed in an electric blast drying oven and dried for 8 h at a temperature of 60°C.

[0032] (6) The dried carbonized hemp stem loaded with TiO2 was placed in a muffle furnace for sintering. The sintering temperature was set to 500°C, the sintering time was 100 min, and the heat preservation time was 60 min. After cooling in the furnace, an ordered porous catalytic material loaded with TiO2 was obtained.

[0033] The degradation rate of the TiO2-loaded ordered porous catalytic material is 92.68%. After repeated recycling and use for 5 times, the degradation efficiency reaches more than 87.36%.

[0034] Example 2

[0035] (1) Cut the hemp stalks into columns with a D:30 and H:30, soak them in a 50% phosphoric acid solution for activation for 12 hours, then soak them in an ethanol solution for 4 hours, and dry them for later use.

[0036] (2) The pretreated hemp stems were carbonized in a vacuum sintering furnace at a sintering temperature of 1000°C, a sintering time of 120 min, and a holding time of 60 min. The vacuum degree reached 1×10 -2 Pa, and take it out after cooling in the furnace.

[0037] (3) Preparation of TiO2 by sol-gel method. The reaction was carried out in a water bath at a constant temperature of 40°C. 8 mL of tetrabutyl titanate was added dropwise to 24 mL of anhydrous ethanol to prepare solution A, and magnetic stirring was applied for 30 min. 16 mL of anhydrous ethanol and 1.25 mL of deionized water were mixed, and 8 mL of glacial acetic acid was added dropwise to adjust the pH value to 1 to prepare solution B. Solution B was added to solution A, and stirring was continued for 2 h. The rotation speed was set to 600 r / min to obtain a mixed solution.

[0038] (4) The carbonized hemp stalks were immersed in the mixed solution and placed in an ultrasonic cleaner for 1.5 h of ultrasonic-assisted immersion. After being taken out, they were naturally dried in a well-ventilated place. TiO2 solution was deposited on the carbonized hemp stalks by using a dropper, and the OMPTA-10 (X is the number of loading times) was naturally hydrolyzed. Then, the OMPTA-10 was placed in the TiO2 solution for aging, and was taken out for drying.

[0039] (5) The TiO2-loaded carbonized hemp stalks were placed in an electric heating air drying oven for drying for 8 h, with a temperature setting of 60°C.

[0040] (6) The dried TiO2-loaded carbonized hemp stalks were sintered in a muffle furnace, with a sintering temperature setting of 500°C, a sintering time of 100 min, and a holding time of 60 min. After cooling in the furnace, the TiO2-loaded ordered porous catalytic material was obtained, as shown in FIG. 1, and as can be seen from FIG. 2, the TiO2-loaded ordered porous catalytic material retained the natural three-dimensional structure of the hemp stalks, with uniform pore distribution and a pore size of 10-20 μm. TiO2 particles were observed in the pores. Figure 1 Figure 1

[0041] The degradation rate of the TiO2-loaded ordered porous catalytic material was 95.68%, and after being repeatedly recycled and used for 5 times, the degradation efficiency reached more than 90.24%.

[0042] Example 3

[0043] (1) The hemp stalks were cut into columns with a diameter of 30 mm and a height of 40 mm. The hemp stalks were activated by soaking in a phosphoric acid solution with a mass concentration of 60% for 12 h, and then soaked in an ethanol solution for 4 h. The hemp stalks were dried and prepared for use.

[0044] (2) The pretreated hemp stalks were carbonized in a vacuum sintering furnace, with a sintering temperature of 1000°C, a sintering time of 120 min, and a holding time of 60 min. The vacuum degree reached 1×10 -2 Pa, and the hemp stalks were taken out after cooling in the furnace.

[0045] (3) TiO2 was prepared by a sol-gel method. The reaction was carried out in a water bath thermostat, with a reaction temperature of 60°C. 8 mL of n-tetrabutyl titanate was added dropwise to 24 mL of anhydrous ethanol to prepare solution A, which was magnetically stirred for 30 min. 16 mL of anhydrous ethanol and 1.25 mL of deionized water were mixed, and 2 mL of HCL was added dropwise to adjust the pH value to 1 to prepare solution B. Solution B was added to solution A, and stirring was continued for 2 h at a speed of 600 r / min to obtain a mixed solution.

[0046] ​​(4) The carbonized hemp rod is immersed in a mixed solution, placed in an ultrasonic cleaner for 2h of ultrasonic assisted immersion, taken out and placed in a dry and ventilated place for natural air drying, and the TiO2 solution is deposited on the carbonized hemp rod using a dropper for natural hydrolysis. OMPTA-20 (X is the number of loadings), and then placed in the TiO2 solution for aging, and taken out for drying.

[0047] (5) The TiO2-loaded carbonized hemp rod is placed in an electric heating air drying oven for drying for 8h, with a temperature setting of 60℃.

[0048] (6) The dried TiO2-loaded carbonized hemp rod is sintered in a muffle furnace, with a sintering temperature setting of 500℃, a sintering time of 100min, and a holding time of 60min. After cooling in the furnace, the TiO2-loaded ordered porous catalytic material is obtained, as shown in FIG. 1. Figure 2 As shown in FIG. 2, the diffraction peaks of TiO2 can be observed, indicating that TiO2 is successfully loaded on the carbonized hemp rod template. Figure 2

[0049] The degradation rate of the TiO2-loaded ordered porous catalytic material is 97.89%, and after 5 times of repeated recycling, the degradation efficiency reaches more than 92.47%.

[0050] Example 4

[0051] (1) The hemp rod is sawn into small pieces, soaked in a 50% mass concentration phosphoric acid solution for activation treatment for 12h, then soaked in an ethanol solution for 4h, and dried for standby use.

[0052] (2) The pretreated hemp rod is carbonized in a vacuum sintering furnace, with a sintering temperature of 1000℃, a sintering time of 120min, and a holding time of 60min. The vacuum degree reaches 1×10 -1 Pa, and after cooling in the furnace, it is taken out and ground in a mortar to pass through a 300 mesh sieve for standby use.

[0053] (3) TiO2 is prepared by sol-gel method; in a water bath constant temperature, the reaction temperature is 60℃, 8mL of n-tetrabutyl titanate is added dropwise into 24mL of anhydrous ethanol to prepare A solution, and magnetically stirred for 30min; 16mL of anhydrous ethanol and 1.25mL of deionized water are mixed, 2mL of HCL is added dropwise to adjust the PH value to 1 to prepare B solution; the B solution is added to the A solution, stirred for 30min to obtain a mixed solution; 1g of ground hemp rod carbon powder is poured into the mixed solution and continues to be stirred until a gel is formed, and the rotation speed is set to 600r / min.

[0054] (4) The C / TiO2 gel is taken out and dried in an electric heating air drying oven for 5h, with a temperature setting of 40℃.

[0055] ​(6) The dried C / TiO2 gel is sintered in a muffle furnace, the sintering temperature is set to 500 DEG C, the sintering time is 100 min, the holding time is 60 min, and the sintered product is ground into fine powder to obtain a C / TiO2 composite powder photocatalyst, as shown in FIG. 2. Figure 3 The diffraction peaks of TiO2 can be observed, and the diffraction peak intensity is higher than that of the TiO2 powder. Figure 3 . Figure 2 .

[0056] The photocatalytic degradation rate of the composite powder is 96.95%, and the degradation efficiency is above 91.64% after repeated recycling for 5 times.

[0057] Comparative Example 1

[0058] Iron-modified vinasse biochar loaded with nano-TiO2 (CN 114891511 A)

[0059] The iron-modified vinasse biochar loaded with nano-TiO2 material prepared by loading TiO2 on carbon powder prepared from vinasse and then performing iron modification treatment on the surface of the carbon powder is applied to reduce Cd in soil. The prepared method obtains a powder aggregation material, and recycling is not convenient.

[0060] In Example 1, hemp stem carbon is used as a template, the natural three-dimensional structure is retained, the pore distribution is uniform, and the pore size is 10-20 μm.

[0061] Comparative Example 2

[0062] Biochar (ramie stem) loaded TiO2 composite material (CN 105688875 A)

[0063] The biomass powder is immersed in a tetra-n-butyl titanate and anhydrous ethanol aqueous solution, a biomass-containing gel is prepared, and the gel is pyrolyzed in a tube furnace under N2 atmosphere to obtain a biochar loaded TiO2 composite material. The method uses biomass powder as a template to prepare an extremely fine particle composite material for wastewater dye degradation. The fine powder is also not provided with a three-dimensional ordered structure and is aggregated.

[0064] As can be seen from the comparison, the present application utilizes the natural hollow and ordered mesoporous structure of hemp stem to load TiO2, the pores are uniform, a three-dimensional ordered interconnected structure and a large specific surface area can be formed, recycling is convenient, and the photocatalytic efficiency is improved.

Claims

1. A method for preparing an ordered porous photocatalytic material of carbonized hemp stalk template carbon loaded with TiO2, characterized in that: The specific steps include: (1) Pretreatment of hemp stem template: Cut the hemp stem into the required shape, immerse it in phosphoric acid solution for activation, then dehydrate it with anhydrous ethanol and soak it, then take it out and wash it with deionized water; then carbonize it under vacuum conditions, then wash it with an ultrasonic cleaner, take it out and dry it for later use; (2) Preparation of TiO2 by sol-gel method: Select TiO2 precursor, solvent, hydrolysis inhibitor, and deionized water, mix them evenly and then completely hydrolyze to obtain TiO2 solution; (3) TiO2 loading on hemp stem template: Immerse the hemp stem template in TiO2 solution, immerse with ultrasonic wave, take out and dry, place in dry and ventilated place, deposit the TiO2 solution on the hemp stem template and hydrolyze naturally. The number of depositions is recorded as: OMPTA-X, where X is the number of loading times. Then put it in TiO2 solution and let it stand for aging, then take it out and dry it. (4) Sintering: Place the loaded TiO2 in a muffle furnace for sintering; the sintering conditions are: heating rate no greater than 10°C / min, sintering temperature 400°C to 600°C, holding time 30min to 60min, and take it out after cooling in the furnace to obtain an ordered porous catalytic material; The mass percentage concentration of the phosphoric acid solution in step (1) is 40-60%, the immersion time is 6-12 hours, and the dehydration immersion time in the anhydrous ethanol solution is 1-2 hours.

2. The method for preparing the ordered porous photocatalytic material of carbonized hemp stalk template carbon loaded with TiO2 according to claim 1, characterized in that: The solvent in step (2) is one or more of ethanol, propanol, glycerol, methanol, and butanol.

3. The method for preparing the ordered porous photocatalytic material of carbonized hemp stalk template carbon loaded with TiO2 according to claim 2, characterized in that: The hydrolysis inhibitor in step (2) is one or more of glacial acetic acid, hydrochloric acid, and nitric acid.

4. The method for preparing the ordered porous photocatalytic material of carbonized hemp stalk template carbon loaded with TiO2 according to claim 3, characterized in that: The TiO2 precursor in step (2) is one of tetrabutyl titanate, isopropyl titanate, TiCl4, and TiCl3.

5. The method for preparing the ordered porous photocatalytic material of carbonized hemp stalk template carbon loaded with TiO2 according to claim 4, characterized in that: In step (2), the volume ratio of TiO2 precursor, solvent, deionized water and hydrolysis inhibitor is (7-8):(28-40):1.25:(1-8).

6. The method for preparing the ordered porous photocatalytic material of carbonized hemp stalk template carbon loaded with TiO2 according to claim 1 or 5, characterized in that: In step (2), the raw materials are mixed evenly and then placed in a water bath at 40-60°C for complete hydrolysis.

7. The method for preparing the ordered porous photocatalytic material of carbonized hemp stalk template carbon loaded with TiO2 according to claim 6, characterized in that: The ultrasonic-assisted immersion time in step (3) is 60 min to 120 min, until the TiO2 solution forms a gel and is then taken out.

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