Process for the preparation of coconut shell super activated carbon for asphalt vocs inhibitors

Abstract

The application discloses a preparation method of coconut shell super activated carbon for asphalt VOCs inhibitor, and comprises the following steps: (1) selecting materials: the selected raw material is coconut shell; (2) washing: the coconut shell is washed and dried, first washed with distilled water, then washed with anhydrous ethanol, and dried completely after washing to obtain coconut shell powder for use; (3) crushing: the coconut shell is ground and sieved; (4) impregnation: the coconut shell powder is impregnated in an H3PO4-KNO3 solution; (5) carbonization: the coconut shell powder is dried and then carbonized by roasting, and the activated carbon powder is obtained after cooling to room temperature after roasting; (6) activation: the activated carbon powder is activated by microwave and ultrasonic waves to obtain coconut shell super activated carbon powder. The coconut shell super activated carbon powder is obtained by microwave and ultrasonic activation of the activated carbon powder formed by the coconut shell, the specific surface area and pore volume of the activated carbon are effectively improved, more adsorption sites are provided, and the removal effect of asphalt VOCs is significantly improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of asphalt VOCs inhibitors, and more particularly relates to a preparation method of coconut shell super activated carbon for asphalt VOCs inhibitors. BACKGROUND

[0002] A large amount of asphalt fumes is discharged in the production process of asphalt, which not only contains a variety of harmful substances to human body, but also has a strong irritating odor. The composition of asphalt fumes is complex, including carbon ring hydrocarbons, cyclic hydrocarbon derivatives and other compounds such as benzopyrene, benzanthracene, carbazole, diphenyl furan, 4-aldehyde biphenyl, phenanthridine and the like. Among them, a variety of carcinogens represented by benzopyrene are inhaled into the body through the respiratory tract, which seriously endangers human health. Under the increasingly severe environmental protection control, the normal development of the asphalt industry is seriously restricted.

[0003] Coconut shell activated carbon is a high-quality activated carbon produced from coconut shell as raw material, which is black irregular particles and processed by a series of production processes. It has the advantages of good wear resistance, developed void, high adsorption performance, high strength, easy regeneration, economic durability and the like, and more has the functions of decolorization, purification, impurity removal, deodorization, odor removal, carrier, purification, recovery and the like.

[0004] At present, the main methods for treating VOCs are catalytic combustion, condensation, absorption, biochemical method and adsorption method. Among them, the adsorption method is widely used because of its simplicity, practicality, environmental protection and the like. Activated carbon has the advantages of strong adsorption capacity, acid and alkali resistance, heat resistance, abundant raw materials and easy regeneration, and is an excellent adsorbent. Therefore, using activated carbon as an adsorbent has become a more effective method for eliminating VOCs pollution.

[0005] The coconut shell activated carbon product is mainly used for the purification, decolorization, dechlorination and deodorization of drinking water, pure water, wine making, beverages and industrial wastewater, and can also be used for the removal of mercaptans in the oil refining industry. At present, the commonly used coconut shell activated carbon has the problems of small specific surface area and relatively low total pore volume, which leads to low removal rate of asphalt VOCs by coconut shell activated carbon and limits its application in the adsorption of VOCs in the asphalt industry. SUMMARY

[0006] In view of the above defects or improvement needs of the prior art, the present application provides a preparation method of coconut shell super activated carbon for asphalt VOCs inhibitors. Coconut shell powder is added to a H3PO4-KNO3 solution with an appropriate concentration ratio, and after immersion, drying and calcination are performed to make the activated carbon powder form a rich pore structure. Then, the activated carbon powder is subjected to microwave and ultrasonic activation to obtain coconut shell super activated carbon powder, which effectively increases the specific surface area and pore volume of the activated carbon and provides more adsorption sites, thereby significantly improving the removal effect of asphalt VOCs.

[0007] To achieve the above object, according to the present application, a preparation method of coconut shell super activated carbon for asphalt VOCs inhibitor is provided, characterized by comprising the following steps:

[0008] (1) Selecting material: selecting coconut shell as raw material;

[0009] (2) Washing: washing and air-drying the coconut shell selected in step (1), first washing with distilled water, then washing with anhydrous ethanol, and drying after washing;

[0010] (3) Crushing: grinding and crushing the coconut shell dried in step (2) and sieving;

[0011] (4) Immersion: immersing the sieved coconut shell powder in step (3) in H3PO4-KNO3 solution, wherein the H3PO4-KNO3 solution contains H3PO4 and KNO3, and is a mixed solution of H3PO4 and KNO3. Since the traditional H3PO4 activation method has limited activation effect, the specific surface area of the prepared activated carbon is low, and there is no effective method for controlling the pore structure. KNO3 is introduced as an additive in the H3PO4 solution to enhance the pore-forming ability of the activator and achieve the purpose of controlling the pore size of the activated carbon.

[0012] (5) Carbonization: drying the immersed coconut shell powder in step (4) and then performing roasting and carbonization, cooling to room temperature after roasting and carbonization, and obtaining activated carbon powder;

[0013] (6) Activation: microwave activation and ultrasonic activation of the activated carbon powder obtained in step (5) to obtain coconut shell super activated carbon powder.

[0014] Preferably, in step (2), the distilled water washing is 2-3 times, the anhydrous ethanol washing is 3-5 times, the drying temperature is 80-120℃, and the drying time is 18-24h, so that the coconut shell can be washed and dried sufficiently.

[0015] Preferably, in step (3), the particle size of the crushed coconut shell is 100-300μm. Too small or too large particle size is not conducive to the subsequent activation treatment.

[0016] Preferably, in step (4), the H3PO4-KNO3 solution is prepared as follows: adding B grams of H3PO4 solution and C grams of KNO3 solution into A milliliters of distilled water in sequence, wherein A:B:C=20:(3-18):(0.1-0.5), the molar concentration of the H3PO4 solution is 0.2-0.4mol / L, and the molar concentration of the KNO3 solution is 0.05-0.2mol / L. If the ratio of H3PO4 to KNO3 is too high, i.e. too little KNO3 as an additive, NO3 -The nitration reaction with lignin structure in the biomass is insufficient, the etching and hole expansion effect is not obvious, and the specific surface area of the sample is reduced; if the ratio of H3PO4 to KNO3 is too low, that is, too much KNO3 is added as an additive, the oxidation and catalytic hydrolysis of KNO3 are too strong, secondary activation occurs on the pore wall formed by the micro-pores, and excessive etching occurs, which causes the formed pore wall to be penetrated and collapsed, so that the proportion of the micropores of the activated carbon is reduced, and the specific surface area is reduced, therefore, the above numerical range is preferred. When the concentration of H3PO4 and KNO3 in the H3PO4-KNO3 solution is too high, clusters are easily formed on the surface of the activated carbon, and when the concentration is too low, the impregnation effect is not good.

[0017] Preferably, in step (5), the temperature of the calcination is 600-800 DEG C, and the time of the calcination is 3-7 h. The original pores of the activated carbon can be expanded and penetrated by selecting the temperature and time.

[0018] Preferably, in step (6), the microwave power is 300-600 W, the irradiation time of the microwave is 2-4 min, the ultrasonic frequency is 60-80 KHz, and the ultrasonic time is 5-15 min. If the microwave activation power is too low and the time is too short, the activation effect is not obvious; if the microwave activation power is too high and the time is too long, the existing pore structure will be ablated by the microwave radiation, and part of the carbon skeleton will collapse. If the ultrasonic power is too low and the time is too short, the fine activated carbon powder cannot be completely dispersed; if the ultrasonic power is too high and the time is too long, the pore channel will collapse and the particles will be broken, which will reduce the adsorption performance.

[0019] According to another aspect of the present application, an asphalt VOCs inhibitor is also provided, which is characterized in that the preparation method is used for preparation.

[0020] Preferably, the specific surface area of the asphalt VOCs inhibitor is 953 m 2 / g-1247 m 2 / g, and the pore volume of the asphalt VOCs inhibitor is 0.97 m 3 / g-1.03 m 3 / g.

[0021] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0022] 1) The present application uses H3PO4-KNO3 solution as an activator, and the coconut shell powder is immersed in the H3PO4-KNO3 solution with an appropriate concentration ratio. H3PO4 undergoes three stages of diffusion-hydrolysis-impregnation, and forms a H3PO4-biomass crosslinking body with the biomass macromolecules of the coconut shell. After high temperature, the pore channel is formed after washing. In the H3PO4 environment, KNO3 produces NO3 -The nitration reaction occurs with the lignin structure in the biomass, changes the structure of the lignin, reduces the diffusion resistance of H3PO4 in the raw material, and improves the impregnation effect. The NO3 - has strong catalytic degradation ability of lignocellulose, and can quickly hydrolyze macromolecular sugars such as hemicellulose into small molecular substances; at the same time, the NO3 - has strong oxidizing property, can oxidize the biomass raw material or the formed carbon atom at high temperature of calcination, realizes the "etching" of the coconut shell powder raw material and realizes the pore forming. Therefore, the introduction of KNO3 in the H3PO4 solution can enhance the impregnation effect and the pore forming effect of the activator body, and form a rich pore structure.

[0023] 2) The activated carbon powder is activated by microwave and ultrasonic. When the microwave works at a set frequency, the particles absorb microwave energy and generate heat in the process of movement and friction, so as to heat the activated carbon powder. The vibration of the polar molecules in the activated carbon powder material in the microwave environment also helps to generate pore structure of the material. The ultrasonic activation disperses the activated carbon particles and prevents their agglomeration, so that the coconut shell super activated carbon powder is finally obtained, the specific surface area and pore volume of the activated carbon powder are effectively improved, and more adsorption sites are provided, so that the removal effect of asphalt VOCs is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a process flow chart of the preparation method of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0026] Example 1

[0027] A preparation method of coconut shell super activated carbon for asphalt VOCs inhibitor, the preparation process of the coconut shell super activated carbon for asphalt VOCs inhibitor comprises the following steps:

[0028] (1) Selecting materials: selecting coconut shell as raw material;

[0029] (2) Washing: washing and drying the coconut shell selected in step (1), washing twice with distilled water first, and then washing three times with anhydrous ethanol, and drying completely in a 100℃ oven for 20h after washing;

[0030] (3) Crushing: grinding and crushing the coconut shell dried in step (2), and sieving to make the particle size 200μm;

[0031] (4) Impregnation: the sieved coconut shell powder of step (3) is impregnated in a H3PO4-KNO3 solution; wherein the H3PO4-KNO3 solution is prepared as follows: B grams of H3PO4 solution and C grams of KNO3 solution are sequentially added into A milliliters of distilled water, wherein A:B:C = 20:12:0.1, the molar concentration of the H3PO4 solution is 0.2 mol / L, and the molar concentration of the KNO3 solution is 0.05 mol / L;

[0032] (5) Carbonization: the impregnated coconut shell powder of step (4) is dried and then carbonized by calcination at 600°C for 3 hours, and after the calcination is completed, it is cooled to room temperature to obtain activated carbon powder;

[0033] (6) Activation: the carbonized activated carbon powder of step (5) is activated by microwave and ultrasonic, wherein the microwave power is 600 W, the irradiation time is 2 min, the ultrasonic frequency is 60 KHz, and the ultrasonic time is 10 min, to obtain coconut super activated carbon powder.

[0034] Example 2

[0035] A preparation method of coconut super activated carbon for asphalt VOCs inhibitor, the preparation process of the coconut super activated carbon for asphalt VOCs inhibitor comprises the following steps:

[0036] (1) Selecting raw materials: selecting coconut shell as raw material;

[0037] (2) Cleaning: the coconut shell selected in step (1) is cleaned and dried, washed with distilled water for 2 times, and then washed with anhydrous ethanol for 4 times, and after the washing is completed, it is completely dried in an oven at 80°C for 24 hours;

[0038] (3) Crushing: the dried coconut shell of step (2) is ground and crushed, and sieved to have a particle size of 100 μm;

[0039] (4) Impregnation: the sieved coconut shell powder of step (3) is impregnated in a H3PO4-KNO3 solution; the H3PO4-KNO3 solution is prepared as follows: B grams of H3PO4 solution and C grams of KNO3 solution are sequentially added into A milliliters of distilled water, wherein A:B:C = 20:18:0.2, the molar concentration of the H3PO4 solution is 0.4 mol / L, and the molar concentration of the KNO3 solution is 0.2 mol / L.

[0040] (5) Carbonization: the impregnated coconut shell powder of step (4) is dried and then carbonized by calcination at 800°C for 7 hours, and after the calcination is completed, it is cooled to room temperature to obtain activated carbon powder;

[0041] (6) Activation: The activated carbon powder after carbonization in step (5) is subjected to microwave and ultrasonic activation, wherein the microwave power is 300 W, the irradiation time is 4 min, the ultrasonic frequency is 80 KHz, and the ultrasonic time is 5 min, to obtain the coconut shell super activated carbon powder.

[0042] Example 3

[0043] A preparation method of coconut shell super activated carbon for asphalt VOCs inhibitor, the preparation process of the coconut shell super activated carbon for asphalt VOCs inhibitor comprises the following steps:

[0044] (1) Selecting materials: the raw material is coconut shell;

[0045] (2) Washing: the coconut shell selected in step (1) is washed and dried, washed with distilled water for 3 times, and then washed with anhydrous ethanol for 5 times, and then dried in an oven at 120°C for 18h;

[0046] (3) Crushing: the coconut shell dried in step (2) is ground and crushed, and sieved to have a particle size of 300μm;

[0047] (4) Immersion: the sieved coconut shell powder in step (3) is immersed in a H3PO4-KNO3 solution; the H3PO4-KNO3 solution is prepared as follows: B grams of H3PO4 solution and C grams of KNO3 solution are sequentially added into A milliliters of distilled water, wherein A:B:C = 20:3:0.5, the molar concentration of the H3PO4 solution is 0.3mol / L, and the molar concentration of the KNO3 solution is 0.1mol / L.

[0048] (5) Carbonization: the immersed coconut shell powder in step (4) is dried and then subjected to calcination at 700°C for 5h, and then cooled to room temperature to obtain activated carbon powder;

[0049] (6) Activation: the activated carbon powder after carbonization in step (5) is subjected to microwave and ultrasonic activation, wherein the microwave power is 500 W, the irradiation time is 3 min, the ultrasonic frequency is 75 KHz, and the ultrasonic time is 15 min, to obtain the coconut shell super activated carbon powder.

[0050] Example 4

[0051] A preparation method of coconut shell super activated carbon for asphalt VOCs inhibitor, the preparation process of the coconut shell super activated carbon for asphalt VOCs inhibitor comprises the following steps:

[0052] (1) Selecting materials: the raw material is coconut shell;

[0053] (2) Cleaning: The coconut shell selected in step (1) is cleaned and dried, washed with distilled water for 3 times, and washed with anhydrous ethanol for 4 times, and then dried completely in an oven at 100°C for 18h after washing;

[0054] (3) Breaking: The coconut shell dried in step (2) is ground and crushed, and sieved to have a particle size of 100μm;

[0055] (4) Immersion: The sieved coconut shell powder in step (3) is immersed in a H3PO4-KNO3 solution; the H3PO4-KNO3 solution is prepared as follows: B grams of H3PO4 solution and C grams of KNO3 solution are sequentially added to A milliliters of distilled water, wherein A:B:C = 20:8:0.2, the molar concentration of the H3PO4 solution is 0.4mol / L, and the molar concentration of the KNO3 solution is 0.2mol / L.

[0056] (5) Carbonization: The immersed coconut shell powder in step (4) is dried and then carbonized by calcination at 700°C for 5h, and then cooled to room temperature after calcination to obtain activated carbon powder;

[0057] (6) Activation: The carbonized activated carbon powder in step (5) is activated by microwave and ultrasonic, wherein the microwave power is 550W, the irradiation time is 3min, the ultrasonic frequency is 70KHz, and the ultrasonic time is 10min, to obtain coconut shell super activated carbon powder.

[0058] Performance detection

[0059] (1) Specific surface area: The coconut shell super activated carbon obtained in Examples 1-4 for use as a VOCs inhibitor for asphalt is tested for specific surface area by using a full-automatic specific surface area and porosity analyzer with a model number of WBL-830, and the results are shown in Table 1.

[0060] (2) VOCs removal rate of asphalt: 94 parts of 90# asphalt are heated to 130°C, and 6 parts of the coconut shell super activated carbon obtained in Example j for use as a VOCs inhibitor for asphalt is added during stirring; the shear speed is 8000r / min, and the shear time is 40min, to obtain modified asphalt, wherein j = 1, 2, 3, 4, i.e., 94 parts of 90# asphalt + 6 parts of the coconut shell super activated carbon of Example j are mixed to obtain modified asphalt.

[0061] The VOCs release of the modified asphalt is quantitatively analyzed and characterized by using a gas chromatograph-mass spectrometer (GC-MS).

[0062] (3) VOCs removal rate calculation formula of asphalt:

[0063] VOCs removal rate of asphalt = [(M1-M2)M1]*100%

[0064] M1 is the total VOCs concentration of 90# asphalt;

[0065] M2 is the total VOCs concentration of modified asphalt after 90# asphalt is mixed with the coconut shell super activated carbon powder of Example j, wherein j = 1, 2, 3, 4, i.e. the 90# asphalt is mixed with the coconut shell super activated carbon of the above four examples respectively.

[0066] The performance test data of the coconut shell super activated carbon prepared in Examples 1-4 and used as VOCs inhibitor of asphalt are shown in Table 1.

[0067] Table 1 Performance test data table of coconut shell super activated carbon prepared in Examples 1-4

[0068] Test item Specific surface area (m 2 / g) m 3 / g) Example 1 1026 0.99 Example 2 1247 1.03 Example 3 953 0.97 Example 4 1159 1.01

[0069] As can be seen from Table 1, the coconut shell super activated carbon prepared by the method provided by the application and used as VOCs inhibitor of asphalt has high specific surface area and pore volume, wherein the specific surface area is up to 1247 m 2 / g and the highest pore volume is up to 1.03 m 3 / g.

[0070] The asphalt VOCs removal performance test data of the coconut shell super activated carbon prepared in Examples 1-4 and used as VOCs inhibitor of asphalt are shown in Table 2.

[0071] Table 2 Asphalt VOCs removal performance test data table of coconut shell super activated carbon

[0072]

[0073] As can be seen from Table 2, after the coconut shell super activated carbon powder of Examples 1-4 is added into 90# asphalt respectively, the asphalt VOCs removal rates are 35.74%, 55.48%, 35.43% and 46.44% respectively. Among them, the VOCs removal rate of Example 2 is the most significant, which is mainly due to its high specific surface area and large pore volume.

[0074] The application adds an appropriate concentration of H3PO4-KNO3 solution, and after impregnation, drying and calcination are performed, the activated carbon forms a rich pore structure.

[0075] The application activates the activated carbon powder by microwave and ultrasonic, obtains the coconut shell super activated carbon powder, effectively improves the specific surface area and pore volume of the activated carbon, and provides more adsorption sites, which significantly improves the removal effect of asphalt VOCs.

[0076] Those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing coconut shell super activated carbon for use as a VOCs inhibitor in asphalt, characterized in that, Includes the following steps: (1) Material selection: Coconut shells are selected as raw materials; (2) Cleaning: Clean and dry the coconut shells selected in step (1). First wash with distilled water, then wash with anhydrous ethanol, and dry after washing. (3) Crushing: Grind the dried coconut shells from step (2) into powder and then sieve them; (4) Impregnation: The coconut shell powder after sieving in step (3) is impregnated in H3PO4-KNO3 solution, wherein the H3PO4-KNO3 solution contains H3PO4 and KNO3. The H3PO4-KNO3 solution is prepared as follows: B grams of H3PO4 solution and C grams of KNO3 solution are added sequentially to A ml of distilled water, wherein A:B:C = 20:(3~18):(0.1~0.5), the molar concentration of the H3PO4 solution is 0.2mol / L~0.4mol / L, and the molar concentration of the KNO3 solution is 0.05mol / L~0.2mol / L; (5) Carbonization: After drying the coconut shell powder impregnated in step (4), it is roasted and carbonized. After the roasting and carbonization is completed, it is cooled to room temperature to obtain activated carbon powder. (6) Activation: The activated carbon powder obtained in step (5) is subjected to microwave activation and ultrasonic activation in sequence. The microwave power is 300W to 600W, the microwave irradiation time is 2min to 4min, the ultrasonic frequency is 60KHz to 80KHz, and the ultrasonic time is 5min to 15min to obtain coconut shell super activated carbon powder.

2. The method for preparing coconut shell super activated carbon for asphalt VOCs inhibitors according to claim 1, characterized in that, In step (2), the distilled water washing is performed 2-3 times, the anhydrous ethanol washing is performed 3-5 times, the drying temperature is 80℃-120℃, and the drying time is 18h-24h.

3. The method for preparing coconut shell super activated carbon for asphalt VOCs inhibitors according to claim 1, characterized in that, In step (3), the particle size of the crushed coconut shell is 100μm-300μm.

4. The method for preparing coconut shell super activated carbon for asphalt VOCs inhibitors according to claim 1, characterized in that, In step (5), the roasting temperature is 600℃-800℃ and the roasting time is 3h-7h.

5. An asphalt VOCs inhibitor, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 4.

6. The asphalt VOCs inhibitor according to claim 5, characterized in that, The specific surface area of ​​the asphalt VOCs inhibitor is 953 m². 2 / g~1247m 2 / g, the pore volume of the asphalt VOCs inhibitor is 0.97m. 3 / g~1.03m 3 / g.

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