Environment-friendly aerogel, preparation process and application thereof

Abstract

The application discloses an environment-friendly aerogel, a preparation process and application thereof, and has the advantages that the preparation process route is simple, waste paper can be recycled and utilized, and the aerogel which can be used as an air particulate matter adsorption material is generated, meanwhile, in the process route, an ultrasonic device is added to disperse and utilize cavitation effect, so that the porosity and compactness of the aerogel material can be effectively increased, the aerogel prepared by the process has excellent particulate matter adsorption effect, and after carbonization, carbonized aerogel with good mechanical properties can be obtained, has good lipophilic and hydrophobic effects, and can be used for treating oil stains in a water environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new materials, and particularly relates to an environment-friendly aerogel, a preparation process and application thereof. BACKGROUND

[0002] Environmental problems are the focus of global attention, among which air pollution and water pollution are the most urgent problems to be solved because they are closely related to people's daily life.

[0003] The problem caused by particulate matter accounts for a large proportion in air pollution. PM particulate matter is also called atmospheric aerosol particles, atmospheric particulate matter or suspended particulate matter. Particulate matter can be divided into primary particulate matter and secondary particulate matter. The primary particulate matter is directly caused by natural pollution sources and human pollution sources. The secondary particulate matter is generated by the chemical reaction of some components of the polluted gas in the atmosphere or the components in the atmosphere (such as oxygen). From the size of the particle diameter, atmospheric particulate matter is divided into inhalable coarse particles, which are called PM10, and fine particles, which are called PM2.5, with a diameter of 2.5 microns or less.

[0004] IARC and WHO consider that particulate matter is the most harmful form of air pollution (except for ultrafine particles), because they can penetrate deep into the lungs and brain from the blood, causing health problems such as heart attacks, respiratory diseases and premature death.

[0005] In addition, the current treatment of oil pollution in water pollution is to use materials for adsorption. However, in the oil-water two-phase system, the specific gravity of the water phase is large, and the existence of a large amount of water phase affects the adsorption effect of the material.

[0006] Therefore, it is of great significance to develop a material with a porous structure, which can effectively hydrophobic and lipophilic, and is environmentally friendly and low in cost.

[0007] Aerogel material is a kind of nano-porous solid material formed by replacing the liquid phase in the gel with gas by a certain drying method. It is the solid with the smallest density in the world, and is a kind of emerging porous material. It also has the performance of high-efficiency filtration of porous materials. However, the existing preparation method of aerogel is relatively complex, and the cost of raw materials is high. Meanwhile, there is no way to prepare the material by using recycled materials.

[0008] In daily and industrial activities, a large amount of waste paper is often generated. Common types of waste paper include office waste paper, newsprint, commercial packaging paper and carton products, etc. These waste papers will form urban solid pollutants, and will also cause certain harm if not properly treated.

[0009] However, there are some problems in the recycling of waste paper, for example: the performance of traditional recycled paper deteriorates in each use cycle, which cannot achieve long-term recycling; it is limited to the application of secondary materials and has no other special performance.

[0010] Therefore, we propose a preparation process of aerogel using waste paper as raw material and its application. SUMMARY

[0011] In view of the problems existing in the prior art, the present application provides an environmentally friendly aerogel, a preparation process and its application to solve the problems raised in the background art.

[0012] An environmentally friendly aerogel, which is prepared from recycled paper as raw material, so that waste paper can be recycled.

[0013] A preparation process of an environmentally friendly aerogel, comprising the following steps:

[0014] M1: take 100 parts by weight of waste paper and cut it;

[0015] M2: soak the waste paper pieces in deionized water;

[0016] M3: use a stirrer to stir thoroughly to obtain uniform paper pulp;

[0017] M4: take 60 parts by volume of the paper pulp from the previous step and add 200 parts by volume of deionized water as reactant A;

[0018] M5: take 2 parts by weight of sodium chlorite and dissolve it in 100 parts by volume of deionized water as reactant B;

[0019] M6: take 2 parts by volume of reactant B and slowly add it to reactant A and dissolve thoroughly;

[0020] M7: adjust the pH value of the solution of the previous step and continue to disperse;

[0021] M8: filter the solid and wash it with deionized water to remove water;

[0022] M9: add ethanol and stir to disperse;

[0023] M10: continue to stir and homogenize, then filter to obtain wet aerogel;

[0024] M11: place the product of the previous step in a blast drying oven to dry to constant weight to obtain aerogel.

[0025] Preferably, the weight ratio of deionized water to waste paper in step M1 is greater than 30 to achieve sufficient soaking.

[0026] Preferably, acetic acid is used in step M7 to control the pH value in the range of 4.5-5.5.

[0027] Preferably, the washing in step M8 comprises the following steps:

[0028] M81: washing with deionized water until the pH is 6.0;

[0029] M82: washing with anhydrous ethanol more than 3 times to remove water.

[0030] Preferably, in step M7, the dispersion is performed by ultrasonic, the temperature is controlled in the range of 70-80℃, and the ultrasonic frequency is 10 kHz. The ultrasonic not only has the dispersion effect, but also increases the local reaction degree through cavitation, and improves the porosity and compactness.

[0031] The application of an environmentally friendly aerogel prepared by a preparation process, the aerogel can be used to filter suspended particulate pollutants in air, and the prepared aerogel has an adsorption rate of PM 2.5 , PM 10 of more than 80%, and can be effectively used for adsorption treatment of particulate matter.

[0032] The application of an environmentally friendly aerogel prepared by a preparation process, the aerogel is used to prepare carbonized aerogel under the condition of 500℃ and air isolation, and the carbonized aerogel is used to treat oil stains in water environment.

[0033] The application has the advantages that: the preparation process is simple, waste paper can be recycled, and aerogel for adsorbing air particulate matter and environmentally friendly treatment material for adsorbing oil stains in water can be generated, which can improve the diversity of waste paper secondary application to a certain extent, the raw material cost is low, the method is safe, the prepared material has good adsorption effect, the carbonized aerogel has good lipophilicity and hydrophobicity and excellent mechanical strength, and can meet the needs of industrial application. The process uses sodium chlorite as a reactant, introduces ultrasonic in the key step, uses the cavitation and dispersion effect to improve the reaction speed and increase the porosity and compactness of the aerogel material. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The electron microscope image of the material prepared by the process without ultrasonic;

[0035] Figure 2 The electron microscope image of the material prepared by the process with ultrasonic;

[0036] Figure 3 The adsorption effect of the aerogel of the application on particulate matter under different flow rates;

[0037] Figure 4 Adsorption effect of the aerogel of the present application on particulate matter in a high humidity environment;

[0038] Figure 5 Long-term continuous adsorption effect of the aerogel of the present application on particulate matter;

[0039] Figure 6 XPS survey spectrum of the aerogel of the present application;

[0040] Figure 7 C1s spectrum of the aerogel of the present application;

[0041] Figure 8 XPS survey spectrum of the carbonized aerogel of the present application;

[0042] Figure 9 C1s spectrum of the carbonized aerogel of the present application;

[0043] Figure 10 Stress-strain curve of the carbonized aerogel of the present application;

[0044] Figure 11 Tendency chart of the maximum stress value in compression of the carbonized aerogel of the present application with the number of cycles. DETAILED DESCRIPTION

[0045] The present application will be further described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0046] An environmentally friendly aerogel, the process of the present application uses recycled waste paper as the main raw material for preparation.

[0047] The preparation process of the specific aerogel includes the following steps:

[0048] M1: 50g of waste paper is cut into pieces. In the process test of the present application, office paper is used as the raw material. In actual industrialization, other types of waste paper can be expanded, of course, the pretreatment work of removing impurities such as metals and plastics should be carried out accordingly

[0049] M2: 50g of waste paper pieces is fully soaked in 1.5L of ionized water. This step can be carried out in a beaker for the laboratory;

[0050] M3: Use a mechanical stirrer to stir thoroughly (such as stirring for more than 3h), and the stirring paddle speed is 720rpm, to obtain uniform pulp;

[0051] M4: If the uniform pulp is stratified after standing, the upper clear liquid is removed, and 60 ml of the lower pulp is taken, diluted with 200 ml of deionized water and stirred uniformly, and used as reactant A;

[0052] M5: 2 g of sodium chlorite is dissolved in 100 ml of deionized water as reactant B;

[0053] M6: 2 ml of reactant B is slowly added to reactant A and dissolved thoroughly;

[0054] M7: The pH value is controlled in the range of 4.5-5.5 with acetic acid, and dispersion is continued, and the temperature is recommended to be maintained at 70-80°C, and the optimal mode is 80°C, and the pH is controlled at 4.5.

[0055] M8: The solid is filtered, washed with deionized water until the pH is 6.0, and then washed with ethanol at least 3 times until the water is removed;

[0056] M9: 300 ml of ethanol is added and stirred and dispersed;

[0057] M10: After continuous mechanical stirring and homogenization, the product is filtered by suction filtration, and the material on the filter paper is a wet aerogel;

[0058] M11: The product of the previous step is placed in a forced air drying oven to dry to constant weight, and an aerogel is obtained.

[0059] In the above M7 step, we introduce an ultrasonic device, which can be a tank-type ultrasonic generator and a probe-type generator. The tank-type generator has uniform ultrasonic waves but generally has low power, and the probe-type generator has high power but has a limited range, so the actual situation is selected (the difference between the two is not large in the laboratory), for example, the probe type can be used for small reactors, and the tank type is recommended for large industrial reactors, but more ultrasonic transducers should be provided.

[0060] For the above-mentioned increase in ultrasonic equipment, the conventional idea is only to use ultrasonic waves as a dispersion means, and the high pressure and high heat generated by cavitation are not considered for process application. According to the conventional thinking, the dispersion effect is increased, and the ultrasonic frequency is increased to increase the energy density. For the process of the present application, the ultrasonic frequency is 10 kHz, although 20 kHz is a commonly used frequency, but in actual tests, 10 kHz is better, which is related to the reaction temperature of 80°C. The increase in temperature makes the microbubbles under cavitation more likely to form, but the increase in frequency makes the microbubbles break down before they are fully inflated, thereby reducing the cavitation effect, i.e., reducing the pressure and temperature generated when the microbubbles break. The process of the present application reduces the ultrasonic frequency so that the microbubbles generated by cavitation have enough time to break down, thereby improving the cavitation effect and facilitating the process.

[0061] The two aerogels prepared by the process of the application are characterized by electron microscopy, and the characterization graphs are as shown in Figure 1 and 2 wherein the aerogel product introduced with the ultrasonic condition is 2, it can be seen that the fibrous structure is more delicate, so the porosity is higher, that is, the specific surface area is larger, which is more conducive to adsorption. The introduction of ultrasonic conditions can effectively improve the dispersion effect by using the cavitation effect generated by ultrasonic, and the high heat and high pressure generated by cavitation are conducive to the formation of porous structure and the densification of the material.

[0062] Further, in order to verify the adsorption effect of the aerogel prepared by the process of the application, the aerogel material prepared by the ultrasonic condition is cut into a film shape with a diameter of 25 mm and a thickness of 1 mm, and is packaged in a self-made filter device for filtration performance test.

[0063] The adsorption efficiency of PM 0.3 , PM 2.5 and PM 10 in flue gas and flow rate were studied, and the flow rate of flue gas was controlled at 0.2 L / min, 0.4 L / min, 0.6 L / min, 0.8 L / min and 1.0 L / min. The filtration efficiency under different flow rates was studied, and the data graph is as shown in Figure 3 It can be seen that the filtration efficiency of PM 2.5 and PM 10 maintains above 90%, which has good filtration efficiency.

[0064] The flow rate of flue gas was maintained at 1.0 L / min, and the environmental humidity was controlled above 90%. After continuous test for 6 h, the data graph is as shown in Figure 4 It can be seen that the filtration effect of the three different particle sizes of particles can be maintained above 90%

[0065] In addition, a long-term filtration test of the aerogel was also conducted, that is, the flow rate of flue gas was controlled at 1.0 L / min, and the filtration under continuous filtration for 72 h was studied, and the data is as shown in Figure 5 It can be seen that the filtration effect of the three particles is above 95%, which reflects high stability.

[0066] In addition, the aerogel prepared in the application is carbonized at 500℃ under nitrogen atmosphere to prepare carbonized aerogel.

[0067] The XPS total spectrum and C1s spectrum of the original aerogel are as shown in Figure 6 and 7 It can be seen that there are obvious C and O element peaks, specifically C-C, C-O-C and O-C=O three carbon peaks;

[0068] The XPS total spectrum and C1s spectrum of the carbonized aerogel are as shown inFigure 8 and 9 As shown in FIG. 6, it is found that the O peak after carbonization is weakened, indicating that the O element in the material structure is released from the structure as the temperature rises, and the C element increases, while the carbon peak of the oxygen-containing group decreases with carbonization, indicating the successful carbonization of the material. Thus, it is proved that it has strong lipophilicity and hydrophobicity effect, and can be used for treating oil pollution in water environment.

[0069] In addition, the carbonized aerogel prepared by the process of the present application also has high mechanical strength, and can be industrialized and applied. Specifically, the carbonized aerogel is compressed to 20%, 40% and 60% of the original height, respectively, and the stress-strain curves under different strains are tested as shown in FIG. 9, and the carbonized aerogel is compressed to 60% of the original height, and the stress-strain curves after 10 times of continuous cyclic compression are measured, and the change trend of the maximum stress value in the 10 times of compression with the cycle number is analyzed as shown in FIG. 10. Figure 10 Figure 11 As shown in FIG. 10, it can be seen that the maximum stress value changes little and has good stability, so the aerogel prepared by the process of the present application has excellent mechanical strength after carbonization and can cope with collision conditions such as throwing, impact and compression in actual application, and maintains its state, thereby maintaining high stability, meeting the actual application.

[0070] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.​

Claims

1. A preparation process for an environmentally friendly aerogel, characterized in that, Includes the following steps: M1: Take a certain weight of waste paper and chop it into small pieces; M2: Soak the waste paper scraps thoroughly in deionized water; M3: Stir thoroughly with a mixer to obtain a uniform pulp; M4: Take a certain volume of pulp from the previous step and add a certain volume of deionized water as reactant A; M5: Dissolve a certain weight of sodium chlorite in a certain volume of deionized water as reactant B; M6: Take a certain volume fraction of reactant B and slowly add it to reactant A until it is fully dissolved; M7: Adjust the pH of the solution from the previous step and continue dispersing; M8: Filter the solids and wash them with deionized water to remove water; M9: Add ethanol and stir to disperse; M10: After continuous stirring and homogenization, the wet aerogel was obtained by filtration. M11: Place the product from the previous step in a forced-air drying oven and dry to constant weight to obtain an aerogel. In step M2, the weight ratio of deionized water to waste paper is greater than 30. In step M7, acetic acid is used to control the pH value within the range of 4.5-5.

5. The washing process in step M8 includes the following steps: M81: Wash with deionized water until pH 6.0; M82: Wash repeatedly with anhydrous ethanol to remove moisture. In step M7, dispersion is performed using ultrasound, with the temperature controlled at 70-80℃ and the ultrasonic frequency at 10kHz. M1 contains 100 parts by weight of waste paper; The M4 contains 60 parts by volume of pulp and 200 parts by volume of deionized water; The M5 contains 2 parts by weight of sodium chlorite and 100 parts by volume of deionized water; The M6 ​​contains 2 parts by volume of reactant B.

2. The application of the aerogel prepared by the process according to claim 1, characterized in that, The aerogel can be used to filter particulate pollutants suspended in the air, and the prepared aerogel is effective against PM2.

5. 2.5 PM 10 The adsorption rate is greater than 80%.

3. The application of the aerogel prepared by the process according to claim 1, characterized in that, The aerogel is prepared by isolating air at 500°C and the carbonized aerogel is used to treat oil pollution in aquatic environments.

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