Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide the environment-friendly formaldehyde-removing activated carbon and the preparation method thereof, and the environment-friendly formaldehyde-removing activated carbon is mainly used for removing formaldehyde gas for a long time.
The invention has the following inventive concept: the graphene oxide and the metal oxide cooperate to modify the activated carbon, so that the formaldehyde removal capacity is improved; further, the polymer-loaded 3, 5-dimethylpyrazole-1-formamidine hydrochloride and formaldehyde are subjected to nucleophilic addition reaction, so that the formaldehyde is harmlessly converted and the activated carbon is regenerated in situ, and further the formaldehyde is thoroughly and long-acting purified.
The invention is realized by adopting the following technical scheme:
a preparation method of environment-friendly formaldehyde-removing activated carbon comprises the following steps:
(1) mixing activated carbon with solid weak acid, and drying to obtain acidified activated carbon;
(2) mixing the acidified activated carbon with graphene oxide, metal oxide and ethanol, and drying at 70-90 ℃ for 20-40 hours to obtain graphene modified activated carbon;
(3) carrying out carbonization treatment on the graphene modified activated carbon to obtain carbonized activated carbon;
(4) and (3) activating the carbonized activated carbon by using water vapor to obtain the environment-friendly formaldehyde-removing activated carbon.
Preferably, the preparation method of the environment-friendly formaldehyde-removing activated carbon comprises the following steps:
(1) mixing activated carbon with solid weak acid, and drying to obtain acidified activated carbon;
the solid weak acid is citric acid or malic acid; the drying temperature is 80-140 ℃, and the drying time is 4-8 hours; the mass ratio of the active carbon to the solid weak acid is 500 (5-10); the active carbon is coconut shell active carbon or coal-based active carbon;
(2) mixing the acidified activated carbon with graphene oxide, metal oxide and ethanol, and drying at 70-90 ℃ for 20-40 hours to obtain graphene modified activated carbon;
the mass ratio of the acidified active carbon to the oxidized graphene to the metal oxide to the ethanol is 2000: (1-3): (2-6): (100-);
the metal oxide is titanium dioxide and/or manganese dioxide;
(3) carrying out carbonization treatment on the graphene modified activated carbon to obtain carbonized activated carbon;
in the carbonization step, the negative pressure is controlled to be 50-100Pa, the carbonization temperature is 500-550 ℃, and the carbonization time is 1-3 hours, so as to obtain carbonized active carbon;
(4) activating the carbonized activated carbon by using steam to obtain the environment-friendly formaldehyde-removing activated carbon;
activating the carbonized activated carbon by using water vapor, activating the carbonized activated carbon for 5 to 25 minutes at 850-900 ℃ under the pressure of 0.1 to 0.3MPa, and cooling the activated carbon to 20 to 30 ℃.
Further preferably, the inventor finds that the addition of polymer-loaded 3, 5-dimethylpyrazole-1-formamidine hydrochloride in the modification process can further improve the formaldehyde-removing performance of the activated carbon, and therefore the following technical scheme is provided.
A preparation method of environment-friendly formaldehyde-removing activated carbon comprises the following steps:
(1) mixing activated carbon with solid weak acid, and drying to obtain acidified activated carbon;
(2) mixing the acidified activated carbon with polymer-loaded 3, 5-dimethylpyrazole-1-formamidine hydrochloride, graphene oxide, metal oxide and ethanol, and drying at 70-90 ℃ for 20-40 hours to obtain graphene modified activated carbon;
the mass ratio of the acidified active carbon to the polymer-loaded 3, 5-dimethylpyrazole-1-formamidine hydrochloride to the graphene oxide to the metal oxide to the ethanol is 2000: (6-14): (1-3): (2-6): (100-);
the metal oxide is titanium dioxide and/or manganese dioxide;
(3) carrying out carbonization treatment on the graphene modified activated carbon to obtain carbonized activated carbon;
(4) and (3) activating the carbonized activated carbon by using water vapor to obtain the environment-friendly formaldehyde-removing activated carbon.
In the invention, carbonization is an important stage for forming the pore structure of the activated carbon. The carbonization is mainly a pyrolysis process, which removes volatile matters and water in the molding material, improves the strength of carbon particles and forms primary pores. Activated carbon activation is one of the most important steps in the production of activated carbon, and activated carbon activation is a process of imparting activity to the carbon so that the carbon eventually forms a porous structure.
The graphene oxide has a large specific surface area, can further increase the efficiency of adsorbing and purifying formaldehyde, and has a long action time. The titanium dioxide and the formaldehyde-removing of the titanium dioxide utilize the catalysis principle, and formaldehyde can be catalyzed and decomposed into carbon dioxide and water by the titanium dioxide under the irradiation of ultraviolet light. And the graphene oxide is compounded with the titanium dioxide, and the graphene oxide has good conductivity and can promote transmission of photo-generated electrons, so that the compounding probability of the photo-generated electrons and holes is reduced, and the formaldehyde removal rate and the bacteriostasis rate are improved. The addition of ethanol in the formulation serves to effect mixing and subsequent evaporation during the subsequent drying process.
Manganese dioxide is an n-type semiconductor whose composition is not completely stoichiometric, always lacks oxygen in small amounts, and when adsorbing oxygen or other oxidizing gases, will adsorb to a lesser extent to replenish oxygen vacancies. Manganese dioxide has a structure containing mixed valence (Mn) 3+ And Mn 4+ ) The octahedral molecular sieve configuration (OMS) that provides manganese dioxide with high activity in catalytic reactions. Manganese dioxide does not need light energy, and organic matters such as formaldehyde and the like can be oxidized at normal temperature through catalytic oxidation only by the strong oxidizing property and the surface property of the manganese dioxide.
In the presence of graphene oxide, titanium dioxide and manganese dioxide can act synergistically, and the catalytic oxidation effect on formaldehyde is more excellent.
The formaldehyde adsorbed on the active carbon and the 3, 5-dimethylpyrazole-1-formamidine hydrochloride loaded on the polymer and loaded on the active carbon have nucleophilic addition reaction, so that the formaldehyde is harmlessly converted and the active carbon is regenerated in situ, and further the formaldehyde is thoroughly and long-acting purified. The polymer-loaded 3, 5-dimethylpyrazole-1-formamidine hydrochloride is used as a nucleophilic addition agent for the first time to be applied to a formaldehyde-removing activated carbon modification process.
The invention also discloses the environment-friendly formaldehyde-removing activated carbon prepared by the method.
The environment-friendly formaldehyde-removing activated carbon disclosed by the invention is good in adsorption performance, has a good antibacterial effect and a good formaldehyde adsorption removal effect, and can be used for removing formaldehyde for a long time.
Detailed Description
The coal-based activated carbon is a 95-mesh model HZYM-0023 coal-based activated carbon provided by Water purification Material Co., Ltd.
Graphene oxide, graphene oxide of 100 mesh item No. 1622 of shanghai gawaring chemical ltd.
Titanium dioxide, anatase titanium dioxide, a10 anatase titanium dioxide, a new material limited of Tianxing, Jiangsu.
Manganese dioxide, Toonao Dry Yao technology, Inc. No. yj0169 manganese dioxide.
Polymer-supported 3, 5-dimethylpyrazole-1-carboxamidine hydrochloride, CAS No.: 40027-64-3, English name: 3,5-dimethylpyrazole-1-carboximidamide, hydrochloride.
Example 1
A preparation method of environment-friendly formaldehyde-removing activated carbon comprises the following steps:
(1) acidifying: mixing coal-based activated carbon and citric acid, wherein the mass ratio of the activated carbon to the citric acid is 75:1, and drying at 120 ℃ for 6 hours to obtain acidified activated carbon;
(2) carrying graphene: uniformly stirring and mixing the acidified active carbon, graphene oxide, titanium dioxide and ethanol, and then drying at 80 ℃ for 30 hours to obtain graphene modified active carbon;
the mass ratio of the acidified active carbon to the oxidized graphene to the titanium dioxide to the ethanol is 2000: 2: 4: 200 of a carrier;
(3) carbonizing: carrying out carbonization treatment on the graphene modified activated carbon to obtain carbonized activated carbon;
in the carbonization step, the negative pressure is controlled at 70Pa, and the carbonization is carried out for 2 hours at the temperature of 500 ℃;
(4) and (3) activation: and (3) activating the carbonized activated carbon by using steam, wherein the pressure of the steam is 0.2MPa, activating the carbonized activated carbon at 900 ℃ for 20 minutes, and naturally cooling the carbonized activated carbon to 25 ℃ to obtain the environment-friendly formaldehyde-removing activated carbon.
Comparative example 1
A preparation method of environment-friendly formaldehyde-removing activated carbon comprises the following steps:
(1) acidifying: mixing coal-based activated carbon and citric acid, wherein the mass ratio of the activated carbon to the citric acid is 75:1, and drying at 120 ℃ for 6 hours to obtain acidified activated carbon;
(2) uniformly stirring and mixing the acidified active carbon, titanium dioxide and ethanol, and then drying for 30 hours at 80 ℃;
the mass ratio of the acidified active carbon to the titanium dioxide to the ethanol is 2000: 4: 200;
(3) carbonizing: carbonizing to obtain carbonized active carbon;
in the carbonization step, the negative pressure is controlled at 70Pa, and the carbonization is carried out for 2 hours at the temperature of 500 ℃;
(4) and (3) activation: and (3) activating the carbonized activated carbon by using water vapor, wherein the pressure of the water vapor is 0.2MPa, the carbonized activated carbon is activated for 20 minutes at 900 ℃, and then the carbonized activated carbon is naturally cooled to 25 ℃ to obtain the environment-friendly formaldehyde-removing activated carbon.
Comparative example 2
A preparation method of environment-friendly formaldehyde-removing activated carbon comprises the following steps:
(1) acidifying: mixing coal-based activated carbon and citric acid, wherein the mass ratio of the activated carbon to the citric acid is 75:1, and drying at 120 ℃ for 6 hours to obtain acidified activated carbon;
(2) carrying graphene: uniformly stirring and mixing the acidified activated carbon, graphene oxide and ethanol, and drying at 80 ℃ for 30 hours to obtain graphene modified activated carbon;
the mass ratio of the acidified active carbon to the graphene oxide to the ethanol is 2000: 2: 200;
(3) carbonizing: carrying out carbonization treatment on the graphene modified activated carbon to obtain carbonized activated carbon;
in the carbonization step, the negative pressure is controlled at 70Pa, and the carbonization is carried out for 2 hours at the temperature of 500 ℃;
(4) and (3) activation: and (3) activating the carbonized activated carbon by using water vapor, wherein the pressure of the water vapor is 0.2MPa, the carbonized activated carbon is activated for 20 minutes at 900 ℃, and then the carbonized activated carbon is naturally cooled to 25 ℃ to obtain the environment-friendly formaldehyde-removing activated carbon.
Comparative example 3
A preparation method of environment-friendly formaldehyde-removing activated carbon comprises the following steps:
(1) acidifying: mixing coal-based activated carbon and citric acid, wherein the mass ratio of the activated carbon to the citric acid is 75:1, and drying at 120 ℃ for 6 hours to obtain acidified activated carbon;
(2) silver is attached: uniformly stirring and mixing the acidified activated carbon, the silver-containing compound and the formaldehyde-removing metal compound, and then drying for 30 hours at the temperature of 80 ℃ to obtain silver-loaded activated carbon;
the mass ratio of the acidified active carbon to the silver-containing compound is 1000:1,
the mass ratio of the acidified active carbon to the formaldehyde-removing metal compound is 1000:1,
the silver-containing compound is formed by mixing silver fluoride and tetrasilver tetroxide according to the mass ratio of 1: 1;
the metal compound for removing formaldehyde is formed by mixing ferric trichloride and cerium nitrate according to the mass ratio of 1: 1;
(3) carbonizing: carrying out carbonization treatment on the silver-loaded activated carbon to obtain carbonized activated carbon;
in the carbonization step, the negative pressure is controlled at 70Pa, and the carbonization is carried out for 2 hours at the temperature of 500 ℃;
(4) activation: and (3) activating the carbonized activated carbon by using water vapor, wherein the pressure of the water vapor is 0.2MPa, the carbonized activated carbon is activated for 20 minutes at 900 ℃, and then the carbonized activated carbon is naturally cooled to 25 ℃ to obtain the environment-friendly formaldehyde-removing activated carbon.
Example 2
A preparation method of environment-friendly formaldehyde-removing activated carbon comprises the following steps:
(1) acidifying: mixing coal-based activated carbon and citric acid, wherein the mass ratio of the activated carbon to the citric acid is 75:1, and drying at 120 ℃ for 6 hours to obtain acidified activated carbon;
(2) carrying graphene: uniformly stirring and mixing the acidified active carbon, graphene oxide, manganese dioxide and ethanol, and then drying at 80 ℃ for 30 hours to obtain graphene modified active carbon;
the mass ratio of the acidified active carbon to the oxidized graphene to the manganese dioxide to the ethanol is 2000: 2: 4: 200 of a carrier;
(3) carbonizing: carrying out carbonization treatment on the graphene modified activated carbon to obtain carbonized activated carbon;
in the carbonization step, the negative pressure is controlled at 70Pa, and the carbonization is carried out for 2 hours at the temperature of 500 ℃;
(4) and (3) activation: and (3) activating the carbonized activated carbon by using water vapor, wherein the pressure of the water vapor is 0.2MPa, the carbonized activated carbon is activated for 20 minutes at 900 ℃, and then the carbonized activated carbon is naturally cooled to 25 ℃ to obtain the environment-friendly formaldehyde-removing activated carbon.
Example 3
A preparation method of environment-friendly formaldehyde-removing activated carbon comprises the following steps:
(1) acidifying: mixing coal-based activated carbon and citric acid, wherein the mass ratio of the activated carbon to the citric acid is 75:1, and drying at 120 ℃ for 6 hours to obtain acidified activated carbon;
(2) carrying graphene: uniformly stirring and mixing the acidified active carbon, graphene oxide, titanium dioxide, manganese dioxide and ethanol, and then drying at 80 ℃ for 30 hours to obtain graphene modified active carbon;
the mass ratio of the acidified active carbon to the oxidized graphene to the titanium dioxide to the manganese dioxide to the ethanol is 2000: 2: 3: 1: 200 of a carrier;
(3) carbonizing: carrying out carbonization treatment on the graphene modified activated carbon to obtain carbonized activated carbon;
in the carbonization step, the negative pressure is controlled at 70Pa, and the carbonization is carried out for 2 hours at the temperature of 500 ℃;
(4) and (3) activation: and (3) activating the carbonized activated carbon by using steam, wherein the pressure of the steam is 0.2MPa, activating the carbonized activated carbon at 900 ℃ for 20 minutes, and naturally cooling the carbonized activated carbon to 25 ℃ to obtain the environment-friendly formaldehyde-removing activated carbon.
In the invention, in the presence of graphene oxide, titanium dioxide and manganese dioxide can act synergistically, and the catalytic oxidation effect on formaldehyde is more excellent. Preferably, the mass ratio of titanium dioxide to manganese dioxide is (2-8): 1.
example 4
A preparation method of environment-friendly formaldehyde-removing activated carbon comprises the following steps:
(1) acidifying: mixing coal-based activated carbon and citric acid, wherein the mass ratio of the activated carbon to the citric acid is 75:1, and drying at 120 ℃ for 6 hours to obtain acidified activated carbon;
(2) carrying graphene: uniformly stirring and mixing the acidified active carbon, the polymer-loaded 3, 5-dimethylpyrazole-1-formamidine hydrochloride, the graphene oxide, the titanium dioxide and the ethanol, and then drying for 30 hours at 80 ℃ to obtain graphene modified active carbon;
the mass ratio of the acidified active carbon to the polymer-loaded 3, 5-dimethylpyrazole-1-formamidine hydrochloride to the graphene oxide to the titanium dioxide to the ethanol is 2000: 10: 2: 4: 200 of a carrier;
(3) carbonizing: carrying out carbonization treatment on the graphene modified activated carbon to obtain carbonized activated carbon;
in the carbonization step, the negative pressure is controlled at 70Pa, and the carbonization is carried out for 2 hours at the temperature of 500 ℃;
(4) and (3) activation: and (3) activating the carbonized activated carbon by using water vapor, wherein the pressure of the water vapor is 0.2MPa, the carbonized activated carbon is activated for 20 minutes at 900 ℃, and then the carbonized activated carbon is naturally cooled to 25 ℃ to obtain the environment-friendly formaldehyde-removing activated carbon.
Test example 1
And (3) testing antibacterial performance: escherichia coli DH5 alpha is selected as the strain of the experiment, and the culture medium adopts LB culture medium.
The experiment was performed using a shaking flask method. Preparing LB culture medium, respectively adding 0.05g of the environment-friendly formaldehyde-removing activated carbon in the conical flask with the plug containing 100ml of the culture medium, and respectively inoculating escherichia coli in the culture medium to ensure that the concentration of initial bacterial liquid is 1.0 multiplied by 10 5 cfu/ml. The cells were put into a constant temperature shaking incubator and subjected to shaking culture at 37 ℃. The concentration of the bacterial suspension was measured by the dilution plate method at 120 minutes of culture.
LB solid medium: 1% tryptone, 0.5% yeast extract powder, 1% sodium chloride, 1.5% agar powder and distilled water. Preparation: adding distilled water into the above components, stirring to dissolve, adjusting pH to 7.2 with 0.1mol/L sodium hydroxide solution, and autoclaving at 121 deg.C for 30 min.
The antibacterial performance of the environment-friendly formaldehyde-removing activated carbon is tested, and the results are shown in table 1.
Table 1: silver-loaded activated carbon antibacterial performance test result table
|
E.coli concentration, cfu/ml
|
Example 1
|
315
|
Example 2
|
360
|
Example 3
|
275
|
Comparative example 1
|
570
|
Comparative example 2
|
665
|
Comparative example 3
|
545 |
Test example 2
0.5g of the environment-friendly formaldehyde-removing activated carbon is placed in a 500mL closed space, and 0.50 mu g of formaldehyde is injected. Standing for 24 hours, extracting gas in the closed space, introducing the gas into a mixed solution of acetylacetone and ammonium acetate, heating in a constant-temperature water bath at 60 ℃ for 15 minutes, and measuring an ultraviolet-visible spectrum after the solution changes color to obtain the absorbance of the sample. Then the residual formaldehyde content in the sample can be calculated according to a regression equation so as to obtain the content of the absorbed formaldehyde, and the test method and the process are based on an acetylacetone spectrophotometry of GB/T15516-1995 air quality formaldehyde. The specific data are shown in Table 2.
Table 2: 24 hour formaldehyde adsorption scale
|
Formaldehyde adsorption amount, μ g
|
Example 1
|
0.40
|
Example 2
|
0.35
|
Example 3
|
0.44
|
Example 4
|
0.42
|
Comparative example 1
|
0.27
|
Comparative example 2
|
0.23
|
Comparative example 3
|
0.29
|
Coal quality activityCharcoal
|
0.09 |
Test example 3: test for removing Formaldehyde Long-term effectiveness
And (3) testing by adopting a standard JCT2188-2013 indoor air purification and adsorption material purification performance (I type products: granular adsorption materials and objects: formaldehyde), and calculating the formaldehyde purification efficiency (%).
Table 3: purification efficiency meter
|
Efficiency of formaldehyde purification%
|
Example 1
|
90.2
|
Example 4
|
98.4
|
Comparative example 3
|
86.6 |
The formaldehyde adsorbed on the activated carbon and the 3, 5-dimethylpyrazole-1-formamidine hydrochloride loaded on the polymer and loaded on the activated carbon generate nucleophilic addition reaction to achieve harmless conversion to the formaldehyde and in-situ regeneration to the activated carbon, thereby realizing thorough and long-acting purification effect to the formaldehyde. The polymer-loaded 3, 5-dimethylpyrazole-1-formamidine hydrochloride is used as a nucleophilic addition agent for the first time to be applied to a formaldehyde-removing activated carbon modification process. The long-lasting formaldehyde removal effect of example 4 is significantly superior to that of example 1.