A CsBr-TiO2 composite photodegradation catalyst and its preparation method

Abstract

The present invention provides a CsBr-TiO2 composite photodegradation catalyst and a preparation method. The CsBr-TiO2 composite photodegradation catalyst raw materials include two parts: CsBr-TiO2 powder and modified graphene oxide dispersion. Cesium bromide doping titanium dioxide enables the semiconductor material to respond to photons with longer wavelengths, broadens the semiconductor's spectral utilization range, enhances the titanium dioxide semiconductor's photocatalytic performance, and improves the efficiency of photocatalytic degradation of organic pollutants. The modified graphene oxide dispersion improves its dispersibility, addresses the defect of its small particle size and easy agglomeration, increases its contact area with TiO2, accelerates electron transmission, and thus enhances the photocatalytic effect of TiO2.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment flocculants, and in particular to a CsBr-TiO2 composite photodegradation catalyst and a preparation method thereof. Background Art

[0002] With the rapid development of my country's manufacturing industry, the consumption of various energy materials has also released a large amount of harmful substances into the environment, causing serious damage to the environment and ecosystem. In the shoe manufacturing process, the emission of organic pollutants is becoming increasingly serious. Therefore, the purification and treatment of organic pollutants has become urgent, and the selection of appropriate treatment methods has become a hot topic of research.

[0003] Rubber is a natural elastic material composed of high molecular weight molecules. Due to its excellent elasticity, wear resistance, and corrosion resistance, it is widely used in industries such as furniture, automobiles, construction, and electronics. However, rubber is not thermally degradable. Excessive use can pollute the environment and pose certain health risks to humans. Therefore, developing biodegradable rubber materials to reduce environmental pollution and protect human health is a current research priority. Rubber degradation methods include physical degradation, chemical degradation, and biodegradation. Physical degradation involves degrading rubber through physical processes, such as light exposure and heat treatment. While this method can conserve energy, it can only degrade the surface of the rubber and cannot completely degrade it. Chemical degradation involves degrading rubber through chemical processes, such as oxidation and hydrolysis. While this method can completely degrade rubber, it can be complex and energy-intensive. Biodegradation involves the use of microorganisms, such as bacteria and fungi, to break down rubber into carbohydrates, amino acids, and other substances. The advantages of rubber degradation are a simple reaction process and low energy consumption. However, the disadvantage is that it takes time to complete degradation. To effectively manage organic pollutants, the waste and pollutants generated during rubber degradation should be of minimal or no environmental concern. Harmful residues are highly detrimental to environmental pollution. The rubber degradation process must be moderate, quickly and efficiently converting waste into beneficial substances, thereby reducing resource waste and allowing more time for subsequent treatment. The cost of rubber degradation should be moderate, otherwise its industrial application will be limited. Therefore, new rubber degradation technologies must meet economic requirements. We are currently using photodegradation to increase the rate of rubber degradation. Sunlight accelerates rubber aging. Under illumination, active free radicals are generated within polymer materials. These free radicals act on molecular sites prone to chemical changes, such as unsaturated bonds and other weakly bonded sites, causing them to break or recombine. The softening of rubber and plastics due to aging is due to molecular breakage, while the hardening or brittleness of plastic products is due to molecular recombination. We have analyzed the accelerating effect of light on aging. Polymer materials are affected by light, especially particles with higher energy in the light, such as ultraviolet particles. These particles act as initiators, causing valence bonds inside the polymer materials to break and recombine, which manifests itself macroscopically as aging.The patent with publication number "CN110975894B" discloses a nano CsPbBr2 / TiO2 composite photocatalyst with high efficiency and stability in visible light response and its preparation method. The prepared composite photocatalyst has high catalytic activity, high recycling and reuse rate, can quickly degrade organic pollutants in aqueous solution and has good water resistance. It can work stably for a long time in the water system. However, the invention has insufficient dispersibility in water and cannot make the organic pollutants undergo photocatalytic reaction uniformly; the patent with publication number "CN105251453A" discloses a preparation method and application of a graphene / cellulose / titanium dioxide nanocomposite material, first using an improved Hummers method to prepare graphite oxide, then obtaining graphene oxide by ultrasound, and then reducing the graphene oxide to graphene using sodium borohydride; finally, cellulose, titanium dioxide, surfactant hexadecyltrimethylammonium bromide and graphene are evenly mixed to obtain a graphene / cellulose / titanium dioxide composite material. The material is in powder form and is mainly used as an adsorption material, not a photocatalytic material. It cannot increase the photodegradation rate under natural light, and its preparation method is complicated.

[0004] In view of the problems existing in the prior art, the present application aims to solve the problems of slow degradation speed and difficulty in dispersion of photodegradation catalysts. Summary of the Invention

[0005] Purpose of the invention:

[0006] The purpose of the present invention is to provide a CsBr-TiO2 composite photodegradation catalyst, which is doped with cesium bromide into titanium dioxide and compounded with a modified graphene oxide dispersion. The catalyst overcomes the problems of slow degradation of organic matter and poor dispersibility in treating sewage by current photodegradation catalysts, and effectively reduces the damage of organic pollutants to the environment.

[0007] The technical solution of the present invention:

[0008] A CsBr-TiO2 composite photodegradation catalyst is characterized in that the raw materials of the CsBr-TiO2 composite photodegradation catalyst include: CsBr-TiO2 powder and modified graphene oxide dispersion.

[0009] The preparation method of the CsBr-TiO2 powder comprises the following steps:

[0010] (1) CsBr-TiO2 gel was prepared by sol-gel method: butyl titanate was added to anhydrous ethanol, stirred for 10-20 min, and then glacial acetic acid was added and stirred to obtain solution A;

[0011] (2) Take nitric acid solution, add it to anhydrous ethanol, and stir evenly to obtain solution B;

[0012] (3) Solution B is slowly added dropwise to solution A, and stirred for 1 to 2 hours after the addition is complete. Then, cesium bromide is added and magnetic stirring is performed until a transparent gel is formed. The resulting gel is allowed to stand at room temperature, dried, ground, calcined, and then cooled to room temperature to obtain CsBr-TiO2 powder.

[0013] Preferably, in the preparation method of the CsBr-TiO2 powder, the mass ratio of cesium bromide to butyl titanate is 1:4-10.

[0014] Preferably, in the method for preparing the CsBr-TiO2 powder, the gel obtained in step (3) is allowed to stand at room temperature for 12 to 48 hours, the drying temperature is 75 to 95°C, the drying time is 12 to 24 hours, the calcination temperature is 400-800°C, and the calcination time is 4 to 6 hours.

[0015] The preparation method of the modified graphene oxide dispersion comprises the following steps:

[0016] (1) dissolving graphene oxide in a mixture of an organic solvent and deionized water to obtain a graphene oxide dispersion, adding ethylenediamine to the dispersion, and performing a heating reaction;

[0017] (2) After adjusting the temperature of the reaction system in step (1) to an appropriate range, continue to add toluene diisocyanate to step (1) to react;

[0018] (3) The product obtained from the reaction in step (2) is washed with acetone and dried to obtain a modified graphene oxide dispersion.

[0019] Preferably, the raw materials of the modified graphene oxide dispersion include, by weight, 10-15 g of graphene oxide, 10-50 g of ethylenediamine, 20-100 g of toluene diisocyanate, and 500-2000 g of an organic solvent.

[0020] Preferably, the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and 1,4-dioxane.

[0021] Preferably, the reaction temperature in step (1) is 90-120° C., and the reaction time is 4-12 hours; the temperature in step (2) is adjusted to a suitable range of 50-80° C., and the reaction time is 4-12 hours; and the drying temperature in step (3) is 45-60° C., and the drying time is 1-2 hours.

[0022] The present application provides a method for preparing a CsBr-TiO2 composite photodegradation catalyst, which is characterized by comprising: adding a modified graphene dispersion into a three-necked flask with a stirring device under nitrogen protection, then adding CsBr-TiO2 powder, stirring, ultrasonicating, heating, drying, and grinding to obtain the CsBr-TiO2 composite photodegradation catalyst.

[0023] Preferably, the mass ratio of the CsBr-TiO2 powder to the modified graphene oxide dispersant is 100:1-10.

[0024] Preferably, the ultrasonic power is 250-300W, the ultrasonic time is 20-50min, and the ultrasonic frequency is 20-50kHz; the heating temperature is 120-180°C, and the heating time is 12-18h; the drying is vacuum drying, the vacuum drying temperature is 60-80°C, and the vacuum drying time is 12h-24h.

[0025] The present invention dopes titanium dioxide with cesium bromide to broaden the spectral utilization range of semiconductors, has excellent photocatalytic performance, enhances the efficiency of photocatalytic degradation of organic pollutants, modifies the graphene oxide dispersion, improves its dispersibility, solves the defect of its small particle size and easy agglomeration, increases its contact area with TiO2, accelerates electron transmission, and thus enhances the photocatalytic effect of TiO2.

[0026] Beneficial effects:

[0027] The CsBr-TiO2 composite photodegradation catalyst provided by the present invention utilizes CsBr-TiO2 powder, exhibiting excellent photocatalytic performance and high efficiency in photocatalytic degradation of organic pollutants. The modified graphene oxide dispersion overcomes the drawbacks of small particle size and easy agglomeration, increasing the contact area between the graphene oxide and the TiO2 and enhancing the photocatalytic effect of the TiO2. The prepared CsBr-TiO2 composite photodegradation catalyst exhibits a rapid photodegradation rate and has promising development prospects for environmental protection. DETAILED DESCRIPTION

[0028] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following examples are illustrative of the present invention and are intended only to illustrate the present invention and are not intended to limit the present invention. Other combinations and various modifications within the scope of the present invention may be made without departing from the spirit or scope of the present invention.

[0029] Unless otherwise specified, the chemical reagents used in the present invention are all commercially available analytical grade.

[0030] Preparation of CsBr-TiO2 powder A:

[0031] (1) CsBr-TiO2 gel was prepared by sol-gel method: 10 g of butyl titanate was added to 30 ml of anhydrous ethanol, stirred for 10 min, and then 5 ml of glacial acetic acid was added and stirred to obtain solution A;

[0032] (2) Take 6 mL of 1.6 mol / L nitric acid solution, add it to 8 mL of anhydrous ethanol, and stir magnetically for 30 min to form solution B;

[0033] (3) Solution B was added dropwise to solution A for 20 minutes. After the addition was complete, stirring was continued for 1 hour. Then 1 g of cesium bromide was added and magnetic stirring was applied until a transparent gel was formed. The resulting gel was allowed to stand at room temperature for 12 hours, dried at 90°C for 18 hours, ground, and then calcined at 500°C for 6 hours. The mixture was cooled to room temperature to obtain CsBr-TiO2 powder A.

[0034] Preparation of CsBr-TiO2 powder B:

[0035] (1) CsBr-TiO2 gel was prepared by sol-gel method: 4 g of butyl titanate was added to 30 ml of anhydrous ethanol, stirred for 10 min, and then 5 ml of glacial acetic acid was added and stirred to obtain solution A;

[0036] (2) Take 6 mL of 1.6 mol / L nitric acid solution, add it to 8 mL of anhydrous ethanol, and stir magnetically for 30 min to form solution B;

[0037] (3) Solution B was added dropwise to solution A for 20 minutes. After the addition was complete, stirring was continued for 1 hour. Then, 1 g of cesium bromide was added and magnetic stirring was applied until a transparent gel was formed. The resulting gel was allowed to stand at room temperature for 12 hours, dried at 90°C for 18 hours, ground, and then calcined at 500°C for 6 hours. The mixture was cooled to room temperature to obtain CsBr-TiO2 powder B.

[0038] Preparation of CsBr-TiO2 powder C:

[0039] (1) CsBr-TiO2 gel was prepared by sol-gel method: 15 g of butyl titanate was added to 30 ml of anhydrous ethanol, stirred for 10 min, and then 5 ml of glacial acetic acid was added and stirred to obtain solution A;

[0040] (2) Take 6 mL of 1.6 mol / L nitric acid solution, add it to 8 mL of anhydrous ethanol, and stir magnetically for 30 min to form solution B;

[0041] (3) Solution B was added dropwise to solution A for 20 minutes, and stirring was continued for 1 hour. Then, 1 g of cesium bromide was added and magnetic stirring was applied until a transparent gel was formed. The resulting gel was allowed to stand at room temperature for 12 hours, dried at 90°C for 18 hours, ground, and then calcined at 500°C for 6 hours. The mixture was cooled to room temperature to obtain CsBr-TiO2 powder C.

[0042] Preparation of modified graphene oxide dispersion A:

[0043] (1) dissolving 10 g of graphene oxide in 1000 g of N,N-dimethylformamide and 1000 g of deionized water to obtain a graphene oxide dispersion, adding 10 g of ethylenediamine to the dispersion for heating reaction at a reaction temperature of 90° C. for 8 h;

[0044] (2) The temperature of the reaction system in step (1) was adjusted to 50° C., and 20 g of toluene diisocyanate was added to step (1) for reaction for 8 h.

[0045] (3) The product obtained from the reaction in step (2) was washed with acetone, dried at 45° C., and dried for 1 h to obtain a modified graphene oxide dispersion A.

[0046] Preparation of modified graphene oxide dispersion B:

[0047] (1) dissolving 10 g of graphene oxide in 1000 g of N,N-dimethylformamide and 1000 g of deionized water to obtain a graphene oxide dispersion, adding 50 g of ethylenediamine to the dispersion for heating reaction at a reaction temperature of 90° C. for 8 h;

[0048] (2) adjusting the temperature of the reaction system in step (1) to 50° C., and continuing to add 100 g of toluene diisocyanate to step (1) for reaction for 8 h;

[0049] (3) The product obtained in step (2) was washed with acetone, dried at 45° C., and dried for 1 h to obtain a modified graphene oxide dispersion B.

[0050] Preparation of modified graphene oxide dispersion C:

[0051] (1) dissolving 15 g of graphene oxide in 1000 g of N,N-dimethylformamide and 1000 g of deionized water to obtain a graphene oxide dispersion, adding 60 g of ethylenediamine to the dispersion for heating reaction at 90° C. for 8 h;

[0052] (2) adjusting the temperature of the reaction system in step (1) to 50° C., and continuing to add 10 g of toluene diisocyanate to step (1) for a reaction time of 8 h;

[0053] (3) The product obtained in step (2) was washed with acetone, dried at 45° C., and dried for 1 h to obtain a modified graphene oxide dispersion C.

[0054] Preparation of CsBr-TiO2 composite photodegradation catalyst:

[0055] Under nitrogen protection, modified graphene dispersion was added to a three-necked flask with a stirring device, and then CsBr-TiO2 powder was added. The mixture was stirred at a speed of 200 rpm / min for 1 hour, the ultrasonic power was set to 250 W, the ultrasonic frequency was set to 20 kHz, and the ultrasonication was carried out for 20 minutes. The reaction was heated, the reaction temperature was set to 120°C, and the reaction time was 12 hours. The mixture was vacuum dried at a drying temperature of 60°C, dried for 12 hours, and then ground to obtain a CsBr-TiO2 composite photodegradation catalyst.

[0056] Examples 1 to 6

[0057] The CsBr-TiO2 composite photodegradation catalyst was prepared according to the above-mentioned preparation method. Table 1 is the ingredient list of the CsBr-TiO2 composite photodegradation catalyst of Examples 1 to 6.

[0058] Table 1 Ingredients of CsBr-TiO2 composite photodegradation catalysts of Examples 1 to 6

[0059]

[0060] Comparative Examples 1 to 6

[0061] The CsBr-TiO2 composite photodegradation catalyst was prepared according to the above-mentioned preparation method. Table 2 is the ingredient list of the CsBr-TiO2 composite photodegradation catalyst of Comparative Examples 1 to 6.

[0062] Table 2 Ingredients of CsBr-TiO2 composite photodegradation catalysts for comparative examples 1 to 6

[0063]

[0064] Comparative Example 7:

[0065] Under nitrogen protection, 5 g of modified graphene dispersion A was added to a three-necked flask with a stirring device, and then 100 g of CsBr-TiO2 powder A was added. The mixture was stirred at a speed of 200 rpm / min for 2 h and then directly dried at 60 ° C for 1 h to prepare a CsBr-TiO2 composite photodegradation catalyst.

[0066] Performance test experiment:

[0067] 1. Tensile elongation at break: Plastic specimens measuring 2*2*0.2cm (plastic specimens purchased from Shanghai Petrochemical Co., Ltd. as polystyrene plastic) were subjected to a photodegradation test. The photodegradation exposure method was exposure in an artificial accelerated aging chamber using a xenon lamp. According to standard GB / T16422.2, the xenon lamp radiation energy was 26MJ / m3, the black mark temperature was 65±5°C, the relative humidity was 65±5%, the water spraying cycle was 18min±0.5min per spray, and the interval between two water sprays was 102min±0.5min. The test was performed after five water sprays. According to GB / T 1040, five specimens were tested in each group, and the results were expressed as the arithmetic mean of the test results of the five specimens. The tensile speed was (50±5)mm / min, and the evaluation standard was less than or equal to 5%.

[0068] 2. The activity of the catalyst was studied using photocatalytic degradation of methylene blue as the evaluation standard. The catalytic reaction was implemented as follows: 20 ml of methylene blue solution (100 mg / L) was measured and diluted to 100 mL. 30 mg of the catalyst prepared above was then added to the solution. The solution was first placed in a dark environment for 30 minutes under magnetic stirring, and then moved to a MICROSOLAR300 light source. The reaction was continued for 180 minutes under magnetic stirring. Samples were taken every 30 minutes during the reaction. After each sampling, the solution was filtered with a 0.22 μm filter membrane. After the fifth sampling, the solution was filtered with a 0.22 μm filter membrane and detected by a UV-visible spectrophotometer. The photodegradation rate of the organic pollutants was calculated based on the drawn standard curve.

[0069] Performance test results Table 3:

[0070] Material Tensile elongation at break / % Photodegradation rate / % Example 1 4 87 Example 2 5 90 Example 3 5 88 Example 4 5 88 Example 5 4 89 Example 6 4 87 Comparative Example 1 1 65 Comparative Example 2 1 70 Comparative Example 3 1 68 Comparative Example 4 2 58 Comparative Example 5 1 63 Comparative Example 6 1 62 Comparative Example 7 5 80

[0071] As can be seen from Table 3, the CsBr-TiO2 composite photodegradation catalyst of the present invention has a high photodegradation rate, which is specifically reflected in that, from Comparative Example 1 and Example 2, when the composite photodegradation catalyst containing modified graphene oxide dispersant is used for aging test, the tensile elongation at break is greater and the photodegradation effect is better; Comparative Example 2 is compared with Example 2, and the mass ratio of graphene oxide, ethylenediamine and toluene diisocyanate is unreasonable, and the composite photodegradation catalyst prepared by the modified graphene oxide dispersion has a poor photodegradation effect in the aging test and a low photodegradation rate; From Comparative Example 3 and Examples 2 and 5, it can be seen that when the mass ratio of cesium bromide to butyl titanate is unreasonable, the composite photodegradation catalyst prepared by CsBr-TiO2 powder is poor. The photodegradation effect of the catalyst aging test is not good and the photodegradation rate is low. From the comparison of Comparative Example 4 and Example 4, it can be seen that when the prepared CsBr-TiO2 powder and the prepared modified graphene oxide dispersion do not meet the requirements, the aging effect and photodegradation rate of the prepared composite photodegradation catalyst do not meet the expected effects. From the comparison of Comparative Examples 5 and 6 with Examples 2 and 5, it can be seen that the aging effect and photodegradation rate of the composite photodegradation catalyst prepared using TiO2 powder not doped with cesium bromide and modified graphene oxide dispersion or unmodified graphene oxide dispersion do not meet expectations. From the comparison of Comparative Example 7 with Example 2, it can be seen that different preparation methods of the CsBr-TiO2 composite photodegradation catalyst will affect the photodegradability of the catalyst.

[0072] The present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A CsBr-TiO2 composite photodegradation catalyst, characterized in that: The CsBr-TiO2 composite photodegradation catalyst raw material Including: CsBr-TiO2 powder, modified graphene oxide dispersion; The preparation method of the CsBr-TiO2 powder comprises the following steps: (1) Preparation of CsBr-TiO2 gel by sol-gel method: Add butyl titanate to anhydrous ethanol, stir for 10-20 min, then add glacial acetic acid and stir to obtain solution A; (2) Take nitric acid solution, add it to anhydrous ethanol, stir evenly, and obtain solution B; (3) Solution B was slowly added to solution A, and the mixture was stirred for 1 to 2 hours after the addition was complete. Then, cesium bromide was added and magnetic stirring was performed until a transparent gel was formed. The resulting gel was allowed to stand at room temperature, dried, ground, calcined, and then cooled to room temperature to obtain CsBr-TiO2 powder. In the preparation method of the CsBr-TiO2 powder, the mass ratio of cesium bromide to butyl titanate is 1:4-10; The preparation method of the modified graphene oxide dispersion comprises the following steps: S1: dissolving graphene oxide in a mixture of an organic solvent and deionized water to obtain a graphene oxide dispersion, adding ethylenediamine to the dispersion, and heating the dispersion for reaction; S2: After adjusting the temperature of the reaction system in step S1 to an appropriate range, continue to add toluene diisocyanate to step S1 to react; S3: The product obtained after the reaction in step S2 is washed with acetone and dried to obtain a modified graphene oxide dispersion.

2. The CsBr-TiO2 composite photodegradation catalyst according to claim 1, characterized in that The gel obtained in step (3) of the preparation method of the CsBr-TiO2 powder is allowed to stand at room temperature for 12 to 48 hours, dried at a temperature of 75 to 95°C for 12 to 24 hours, and calcined at a temperature of 400-800°C for 4 to 6 hours.

3. The CsBr-TiO2 composite photodegradation catalyst according to claim 1, characterized in that The raw materials of the modified graphene oxide dispersion include, by weight, 10-15 g of graphene oxide, 10-50 g of ethylenediamine, 20-100 g of toluene diisocyanate, and 500-2000 g of an organic solvent.

4. The CsBr-TiO2 composite photodegradation catalyst according to claim 1, characterized in that In the preparation method of the modified graphene oxide dispersion, the reaction temperature in step S1 is 90-120° C. and the reaction time is 4-12 hours. In the preparation method of the modified graphene oxide dispersion, the temperature in step S2 is adjusted to a suitable range of 50-80° C. and the reaction time is 4-12 hours. In the preparation method of the modified graphene oxide dispersion, the drying temperature in step S3 is 45-60° C. and the drying time is 1-2 hours.

5. The method for preparing the CsBr-TiO2 composite photodegradation catalyst according to any one of claims 1 to 4, characterized in that: include: Under nitrogen protection, a modified graphene dispersion was added to a three-necked flask with a stirring device, and then CsBr-TiO2 powder was added, stirred, ultrasonicated, heated, dried and ground to prepare a CsBr-TiO2 composite photodegradation catalyst.

6. The method for preparing the CsBr-TiO2 composite photodegradation catalyst according to claim 5, characterized in that: The mass ratio of the CsBr-TiO2 powder to the modified graphene oxide dispersant is 100:1-10.

7. The method for preparing the CsBr-TiO2 composite photodegradation catalyst according to claim 5, characterized in that: The ultrasonic power is 250-300W, the ultrasonic time is 20-50min, and the ultrasonic frequency is 20-50kHz; the heating temperature is 120-180°C, and the heating time is 12-18h; the drying is vacuum drying, the vacuum drying temperature is 60-80°C, and the vacuum drying time is 12h-24h.

Images