Method for preparing activated carbon

Abstract

The invention discloses a method for preparing activated carbon, which comprises the following steps: (1) washing, drying and crushing shells to obtain crushed particles; (2) immersing the crushed particles in a hydrogen peroxide solution, stirring, heating, preserving heat, and rapidly cooling to obtain preliminarily activated crushed particles; (3) uniformly mixing the preliminarily activated crushed particles with a phosphoric acid solution, carrying out first-time ball milling, pressing into sheets in a pressure increasing and maintaining manner, crushing, and carrying out second-time ball milling, so as to obtain ground particles; (4) carbonizing the ground particles in a nitrogen atmosphere: firstly heating, preserving heat, then cooling, and naturally cooling to obtain carbonized particles; and (5) immersing the carbonized particles in a phosphoric acid solution, stirring, and carrying out secondary activation in a carbon dioxide gas atmosphere: heating, carrying out vacuum heat preservation, pressurizing and cooling, and naturally cooling to obtain the activated carbon. The activated carbon prepared by the method is uniform in pore distribution and relatively uniform in pore size, and meanwhile, the strength of the activated carbon is improved.

Description

Technical Field

[0001] The invention relates to a method for preparing activated carbon, and belongs to the technical field of activated carbon. Background Art

[0002] Activated carbon is a product that is highly dependent on resources and energy. It can be used not only as a purification material, but also as an activated carbon carrier. The price is affected by many factors such as raw material supply and market demand. With the improvement of environmental awareness and the increasing shortage of resources, fruit shell activated carbon has gradually become the focus of sustainable development.

[0003] At present, activated carbon from fruit shells still has certain defects: 1) The existing preparation process still has certain deficiencies in the control of pore structure, resulting in uneven pore distribution and different pore sizes; 2) The existing activated carbon prepared from fruit shells often has problems such as insufficient strength and poor wear resistance, resulting in a short service life. Therefore, it is necessary to improve the process to prepare activated carbon materials with better performance. Summary of the invention

[0004] In order to address at least one problem existing in the above-mentioned prior art, the present invention provides a method for preparing activated carbon, using fruit shells as raw materials. The prepared activated carbon has uniform pore distribution and relatively uniform pore size, thereby improving the adsorption effect of the activated carbon on substances. At the same time, the strength of the activated carbon is improved, thereby improving the adsorption efficiency and service life of the activated carbon.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme: a method for preparing activated carbon, comprising the following steps:

[0006] (1) washing the fruit shell with deionized water, vacuum drying, and then crushing to obtain crushed particles;

[0007] (2) immersing the crushed particles in a hydrogen peroxide solution with a pH value of 5 to 6, stirring at a temperature of 30 to 35° C. for 2 to 3 hours, filtering to remove the liquid, slowly heating to 250 to 280° C. and keeping the temperature for 30 to 45 minutes, then rapidly cooling to 50 to 60° C., washing, and vacuum drying to obtain preliminarily activated crushed particles;

[0008] (3) mixing the initially activated crushed particles with the phosphoric acid solution, first performing a first ball milling, then pressing into sheets by first rapidly increasing the pressure, then slowly increasing the pressure, and then maintaining the pressure, and finally breaking them into particles, and then performing a second ball milling to obtain ground particles;

[0009] (4) carbonizing the ground particles in a nitrogen atmosphere: first, rapidly heating to 850-900° C. and keeping the temperature for 25-30 min, then slowly cooling to 150-180° C., and then naturally cooling to 30-35° C. to obtain carbonized particles;

[0010] (5) The carbonized particles are immersed in a phosphoric acid solution, and carbon dioxide gas is introduced and stirred for 40 to 45 minutes, and then a second activation is performed in a carbon dioxide atmosphere: first, the temperature is rapidly raised to 620 to 650°C, and then vacuumized and the pressure is maintained for 90 to 120 minutes. Then, carbon dioxide-water vapor is introduced to increase the pressure and the pressure is maintained for a cycle cooling to 120 to 130°C, and then naturally cooled to 50 to 60°C, washed to neutrality, and vacuum dried to obtain activated carbon.

[0011] Preferably, in step (1), the fruit shell is peach kernel, coconut shell, walnut kernel, apricot kernel, date kernel, etc., and the particle size of the crushed particles is 2 to 3 mm.

[0012] Preferably, in steps (1), (2) and (5), the vacuum drying temperature is 40 to 50°C.

[0013] Preferably, in step (2), the concentration of the hydrogen peroxide solution is 12-15% (w / w).

[0014] Preferably, the pH of the hydrogen peroxide solution is adjusted by hydrochloric acid or sulfuric acid.

[0015] Preferably, in step (2), the rate of slow heating is 1-2°C / min; the rate of rapid cooling is 5-8°C / min.

[0016] Preferably, in step (3), the mass of the phosphoric acid solution is 30-35% of the mass of the initially activated pulverized particles.

[0017] Preferably, in steps (3) and (4), the concentration of the phosphoric acid solution is 35-40% (w / w).

[0018] Preferably, in step (3), the diameters of the balls in the first ball milling and the second ball milling are both 0.5 to 1 mm.

[0019] Preferably, in step (3), the first ball milling: the ball milling rate is 300-350 rpm, and the ball milling time is 30-40 min.

[0020] Preferably, in step (3), the second ball milling: the ball milling rate is 200-250 rpm, and the ball milling time is 90-100 min.

[0021] Preferably, in step (3), the pressure for tableting is rapidly increased from 5 MPa to 25 to 30 MPa at a rate of 2 to 3 MPa / min, then slowly increased to 40 to 45 MPa at a rate of 0.5 to 1 MPa / min, and then maintained at this pressure for 10 to 15 min.

[0022] Preferably, in step (4), the rapid heating rate is 5-10°C / min; and the slow cooling rate is 1-2°C / min.

[0023] Preferably, in step (5), the rate of rapid heating is 15-20°C / min.

[0024] Preferably, in step (5), the pressure is evacuated to -0.06 to -0.04 MPa and the pressure is increased to 1.2 to 1.4 MPa.

[0025] The beneficial effects of the present invention are as follows: the method for preparing activated carbon of the present invention uses fruit shells as raw materials, and after crushing, goes through the process of primary activation-pressing and grinding-carbonization-secondary activation, so that the prepared activated carbon has uniform pore distribution and uniform pore size, and has higher adsorption performance and effect; at the same time, the activated carbon has higher strength, thereby improving the adsorption efficiency and service life of the activated carbon; the method for preparing activated carbon of the present invention uses relatively cheap raw materials and reagents, and the process is easy to operate, which is convenient for large-scale industrial production and application. DETAILED DESCRIPTION

[0026] The following is a clear and complete description of the technical solutions in the implementation of the present invention. The described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. If the specific conditions are not specified in the embodiments, they are carried out according to the normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents, instruments, and components used, they are all conventional products that can be purchased commercially.

[0027] Example 1

[0028] A method for preparing activated carbon, the specific steps are as follows:

[0029] (1) washing 2.5 kg of peach pits with deionized water, vacuum drying at 40° C., and then crushing to a particle size of 2 to 3 mm to obtain crushed particles;

[0030] (2) immersing the crushed particles in a 12% (w / w) hydrogen peroxide solution adjusted to pH 5 by sulfuric acid, stirring at a temperature of 30-35° C. for 3 h, filtering to remove the liquid, slowly heating to 250° C. at a rate of 1-2° C. / min and keeping the temperature for 45 min, then rapidly cooling to 60° C. at a rate of 5-8° C. / min, washing twice, and vacuum drying at a temperature of 40° C. to obtain preliminarily activated crushed particles;

[0031] (3) The initially activated crushed particles were uniformly mixed with a 40% (w / w) phosphoric acid solution which was 30% of the mass of the initially activated crushed particles, and the mixture was first ball-milled at a rate of 300 rpm for 40 min, and then the pressure was rapidly increased from 5 MPa to 25 MPa at a rate of 2-3 MPa / min, and then the pressure was slowly increased to 40 MPa at a rate of 0.5-1 MPa / min, and the pressure was maintained for 15 min, and the mixture was pressed into tablets, and then crushed into particles, and then the mixture was ball-milled for the first time at a rate of 200 rpm for 100 min to obtain ground particles, wherein the ball diameters of the first and second ball millings were both 0.5 mm;

[0032] (4) carbonizing the ground particles in a nitrogen atmosphere: first, rapidly heating the particles to 850° C. at a rate of 5 to 10° C. / min and keeping the temperature for 30 min, then slowly cooling the particles to 150° C. at a rate of 1 to 2° C. / min, and then naturally cooling the particles to 35° C. to obtain carbonized particles;

[0033] (5) The carbonized particles were immersed in a 40% (w / w) phosphoric acid solution, and carbon dioxide gas was introduced and stirred for 40 minutes, and then a second activation was carried out in a carbon dioxide atmosphere: first, the temperature was rapidly raised to 620°C at a rate of 15 to 20 / min, and then vacuumed to -0.04 MPa, and the pressure was maintained for 120 minutes. Then, carbon dioxide-water vapor was introduced to increase the pressure to 1.2 MPa and the pressure was maintained and cyclically cooled to 120°C, and then naturally cooled to 50°C, washed to neutral, and then vacuum dried at 40°C to obtain activated carbon. The results of the tests are shown in Table 1.

[0034] Example 2

[0035] A method for preparing activated carbon, the specific steps are as follows:

[0036] (1) washing 2.5 kg of peach pits with deionized water, vacuum drying at 45° C., and then crushing to a particle size of 2 to 3 mm to obtain crushed particles;

[0037] (2) immersing the crushed particles in a 14% (w / w) hydrogen peroxide solution whose pH is adjusted to 5.5 by sulfuric acid, stirring at a temperature of 30 to 35° C. for 2.5 h, filtering to remove the liquid, slowly heating to 260° C. at a rate of 1 to 2° C. / min and keeping the temperature for 40 min, then rapidly cooling to 55° C. at a rate of 5 to 8° C. / min, washing three times, and vacuum drying at a temperature of 45° C. to obtain preliminarily activated crushed particles;

[0038] (3) The initially activated crushed particles were uniformly mixed with a 38% (w / w) phosphoric acid solution which was 30% of the mass of the initially activated crushed particles, and the mixture was first ball-milled at a rate of 330 rpm for 35 min, and then the pressure was rapidly increased from 5 MPa to 28 MPa at a rate of 2-3 MPa / min, and then the pressure was slowly increased to 42 MPa at a rate of 0.5-1 MPa / min, and the pressure was maintained for 13 min, and the mixture was pressed into tablets, and then crushed into particles, and then the mixture was ball-milled at a rate of 220 rpm for 95 min to obtain ground particles, and the ball diameters of the first and second ball millings were both 0.5 mm;

[0039] (4) carbonizing the ground particles in a nitrogen atmosphere: firstly rapidly heating to 880°C at a rate of 5-10°C / min and keeping the temperature for 27 min, then slowly cooling to 165°C at a rate of 1-2°C / min, and then naturally cooling to 30°C to obtain carbonized particles;

[0040] (5) The carbonized particles were immersed in a 38% (w / w) phosphoric acid solution, and carbon dioxide gas was introduced and stirred for 45 minutes. Then, the carbonized particles were activated for the second time in a carbon dioxide atmosphere: first, the temperature was rapidly increased to 635°C at a rate of 15 to 20 / min, and then the temperature was evacuated to -0.05 MPa and the pressure was maintained for 105 minutes. Then, carbon dioxide-water vapor was introduced to increase the pressure to 1.3 MPa and the pressure was maintained and cyclically cooled to 125°C. Then, the particles were naturally cooled to 55°C, washed to neutrality, and then vacuum dried at 45°C to obtain activated carbon. The results of the tests are shown in Table 1.

[0041] Example 3

[0042] A method for preparing activated carbon, the specific steps are as follows:

[0043] (1) washing 2.5 kg of peach pits with deionized water, drying them in a vacuum at 50° C., and then crushing them to a particle size of 2 to 3 mm to obtain crushed particles;

[0044] (2) immersing the crushed particles in a 15% (w / w) hydrogen peroxide solution adjusted to pH 6 by hydrochloric acid, stirring at a temperature of 30 to 35° C. for 2 h, filtering to remove the liquid, slowly heating to 280° C. at a rate of 1 to 2° C. / min and keeping the temperature for 30 min, then rapidly cooling to 50° C. at a rate of 5 to 8° C. / min, washing twice, and vacuum drying at a temperature of 50° C. to obtain preliminarily activated crushed particles;

[0045] (3) The initially activated crushed particles were uniformly mixed with a 35% (w / w) phosphoric acid solution which was 35% of the mass of the initially activated crushed particles, and the mixture was first ball-milled at a rate of 350 rpm for 30 min, and then the pressure was rapidly increased from 5 MPa to 30 MPa at a rate of 2-3 MPa / min, and then the pressure was slowly increased to 45 MPa at a rate of 0.5-1 MPa / min, and the pressure was maintained for 10 min, and the mixture was pressed into tablets, and then crushed into particles, and then the mixture was ball-milled for the first time at a rate of 250 rpm for 90 min to obtain ground particles, wherein the ball diameters of the first and second ball millings were both 0.5 mm;

[0046] (4) carbonizing the ground particles in a nitrogen atmosphere: first, rapidly heating the particles to 900° C. at a rate of 5 to 10° C. / min and keeping the temperature for 25 min, then slowly cooling the particles to 180° C. at a rate of 1 to 2° C. / min, and then naturally cooling the particles to 35° C. to obtain carbonized particles;

[0047] (5) The carbonized particles were immersed in a 35% (w / w) phosphoric acid solution, and carbon dioxide gas was introduced and stirred for 42 minutes. Then, the carbonized particles were activated for the second time in a carbon dioxide atmosphere: first, the temperature was rapidly increased to 650°C at a rate of 15 to 20 / min, and then the temperature was evacuated to -0.06 MPa and maintained at this pressure for 90 minutes. Then, carbon dioxide-water vapor was introduced to increase the pressure to 1.4 MPa and the pressure was maintained and cyclically cooled to 130°C. Then, the particles were naturally cooled to 60°C, washed to neutrality, and then vacuum dried at 50°C to obtain activated carbon. The results of the tests are shown in Table 1.

[0048] Example 4

[0049] A method for preparing activated carbon, the specific steps are as follows:

[0050] (1) washing 2.5 kg of peach pits with deionized water, vacuum drying at 45° C., and then crushing to a particle size of 2 to 3 mm to obtain crushed particles;

[0051] (2) immersing the crushed particles in a 15% (w / w) hydrogen peroxide solution whose pH is adjusted to 5.6 by hydrochloric acid, stirring at a temperature of 30 to 35° C. for 2.5 h, filtering to remove the liquid, slowly heating to 270° C. at a rate of 1 to 2° C. / min and keeping the temperature for 30 min, then rapidly cooling to 55° C. at a rate of 5 to 8° C. / min, washing three times, and vacuum drying at a temperature of 45° C. to obtain preliminarily activated crushed particles;

[0052] (3) The initially activated crushed particles were uniformly mixed with a 40% (w / w) phosphoric acid solution which was 35% of the mass of the initially activated crushed particles, and the mixture was first ball-milled at a rate of 330 rpm for 35 min, and then the pressure was rapidly increased from 5 MPa to 30 MPa at a rate of 2-3 MPa / min, and then the pressure was slowly increased to 40 MPa at a rate of 0.5-1 MPa / min, and the pressure was maintained for 10 min, and the mixture was pressed into tablets, and then crushed into particles, and then the mixture was ball-milled for 90 min at a rate of 230 rpm to obtain ground particles, wherein the ball diameter of the first ball milling was 0.5 mm and the ball diameter of the second ball milling was 1 mm;

[0053] (4) carbonizing the ground particles in a nitrogen atmosphere: firstly rapidly heating the temperature to 890°C at a rate of 5-10°C / min and keeping the temperature for 25 min, then slowly cooling the temperature to 170°C at a rate of 1-2°C / min, and then naturally cooling the temperature to 30°C to obtain carbonized particles;

[0054] (5) The carbonized particles were immersed in a 40% (w / w) phosphoric acid solution, and carbon dioxide gas was introduced and stirred for 42 minutes. Then, the particles were activated for the second time in a carbon dioxide atmosphere: first, the temperature was rapidly raised to 640°C at a rate of 15 to 20 / min, then the particles were evacuated to -0.05 MPa and the pressure was maintained for 90 minutes. Then, carbon dioxide-water vapor was introduced to increase the pressure to 1.3 MPa and the pressure was maintained and the temperature was cooled to 130°C. Then, the particles were naturally cooled to 60°C, washed to neutrality, and then vacuum dried at 50°C to obtain activated carbon. The results of the tests are shown in Table 1.

[0055] Example 5

[0056] A method for preparing activated carbon, the specific steps are as follows:

[0057] (1) washing 2.5 kg of peach pits with deionized water, vacuum drying at 45° C., and then crushing to a particle size of 2 to 3 mm to obtain crushed particles;

[0058] (2) immersing the crushed particles in a 14% (w / w) hydrogen peroxide solution whose pH is adjusted to 5.3 by hydrochloric acid, stirring at a temperature of 30 to 35° C. for 2.5 h, filtering to remove the liquid, slowly heating to 250° C. at a rate of 1 to 2° C. / min and keeping the temperature for 30 min, then rapidly cooling to 60° C. at a rate of 5 to 8° C. / min, washing twice, and vacuum drying at a temperature of 45° C. to obtain preliminarily activated crushed particles;

[0059] (3) The initially activated crushed particles were uniformly mixed with a 40% (w / w) phosphoric acid solution which was 30% of the mass of the initially activated crushed particles, and the mixture was first ball-milled at a rate of 300 rpm for 35 min, and then the pressure was rapidly increased from 5 MPa to 25 MPa at a rate of 2-3 MPa / min, and then the pressure was slowly increased to 40 MPa at a rate of 0.5-1 MPa / min, and the pressure was maintained for 10 min, and the mixture was pressed into tablets, and then crushed into particles, and then the mixture was ball-milled for 90 min at a rate of 200 rpm to obtain ground particles, wherein the ball diameter of the first ball milling was 1 mm and the ball diameter of the second ball milling was 0.5 mm;

[0060] (4) carbonizing the ground particles in a nitrogen atmosphere: firstly rapidly heating the temperature to 850°C at a rate of 5-10°C / min and keeping the temperature for 25 min, then slowly cooling the temperature to 150°C at a rate of 1-2°C / min, and then naturally cooling the temperature to 30°C to obtain carbonized particles;

[0061] (5) The carbonized particles were immersed in a 40% (w / w) phosphoric acid solution, and carbon dioxide gas was introduced and stirred for 40 minutes, and then a second activation was carried out in a carbon dioxide atmosphere: first, the temperature was rapidly raised to 620°C at a rate of 15 to 20 / min, and then vacuumed to -0.04 MPa, and the pressure was maintained for 90 minutes. Then, carbon dioxide-water vapor was introduced to increase the pressure to 1.2 MPa and the pressure was maintained and cyclically cooled to 130°C, and then naturally cooled to 60°C, washed to neutral, and then vacuum dried at 50°C to obtain activated carbon. The results of the tests are shown in Table 1.

[0062] Example 6

[0063] A method for preparing activated carbon, the specific method steps are as follows and are partially the same as those in Example 2, except that walnut kernels are used.

[0064] Example 7

[0065] A method for preparing activated carbon, the specific method steps are as follows and are partially the same as those in Example 2, except that apricot kernels are used.

[0066] Comparative Example 1

[0067] A method for preparing activated carbon, the specific method steps are as follows and are partially the same as those in Example 4, except that: there is no step (2), the crushed particles are not preliminarily activated, and the crushed particles are directly mixed with a phosphoric acid solution for subsequent preparation steps.

[0068] Comparative Example 2

[0069] A method for preparing activated carbon, the specific method steps are as follows and are partially the same as those in Example 4, except that: there is no step (3), the preliminary activated pulverized particles are not ground and pressed, and the preliminary activated pulverized particles are directly carbonized.

[0070] Comparative Example 3

[0071] A method for preparing activated carbon, the specific method steps are as follows and are partially the same as those in Example 4, except that: there is no step (5), and in step (4), the carbonized particles are directly washed to neutrality and then vacuum dried at a temperature of 50°C to obtain activated carbon. After testing, the results are shown in Table 1.

[0072] Comparative Example 4

[0073] A method for preparing activated carbon, the specific method steps are as follows, which are partially the same as those in Example 4, except that: (2) the crushed particles are immersed in a 15% (w / w) hydrogen peroxide solution adjusted to pH 5.6 by hydrochloric acid, and then stirred at a temperature of 30-35°C for 2.5 hours. After filtering to remove the liquid, the mixture is washed three times and then vacuum dried at a temperature of 45°C to obtain initially activated crushed particles.

[0074] Comparative Example 5

[0075] A method for preparing activated carbon, the specific method steps are as follows, which are partially the same as those in Example 4, except that: (2) the crushed particles are immersed in a 15% (w / w) hydrogen peroxide solution adjusted to pH 5.6 by hydrochloric acid, and then stirred at a temperature of 30-35°C for 2.5 hours. After filtering to remove the liquid, the mixture is slowly heated to 300°C at a rate of 1-2°C / min and kept warm for 30 minutes, and then quickly cooled to 55°C at a rate of 5-8°C / min, washed three times, and then vacuum dried at a temperature of 45°C to obtain initially activated crushed particles.

[0076] Comparative Example 6

[0077] A method for preparing activated carbon, the specific method steps are as follows, which are partially the same as those in Example 4, except that: (2) the crushed particles are immersed in a 15% (w / w) hydrogen peroxide solution adjusted to pH 5.6 by hydrochloric acid, and then stirred at a temperature of 30-35°C for 2.5 hours. After filtering to remove the liquid, the temperature is slowly raised to 230°C at a rate of 1-2°C / min and kept warm for 30 minutes, and then the temperature is quickly lowered to 55°C at a rate of 5-8°C / min, washed three times, and then vacuum dried at a temperature of 45°C to obtain initially activated crushed particles.

[0078] Comparative Example 7

[0079] A method for preparing activated carbon, the specific method steps are as follows, which are partially the same as those in Example 4, except that: (2) the crushed particles are immersed in a 15% (w / w) hydrogen peroxide solution adjusted to pH 5.6 by hydrochloric acid, and then stirred at a temperature of 30-35°C for 2.5 hours, after filtering to remove the liquid, and then placed at 270°C for 40 minutes, and then naturally cooled to 55°C, washed 3 times, and then vacuum dried at a temperature of 45°C to obtain initially activated crushed particles.

[0080] Comparative Example 8

[0081] A method for preparing activated carbon, the specific method steps are as follows and are partially the same as those in Example 4, except that: (3) the initially activated crushed particles are evenly mixed with a 40% (w / w) phosphoric acid solution which is 35% of the mass of the initially activated crushed particles, and ball milled at a speed of 330 rpm for 35 minutes to obtain ground particles with a ball diameter of 0.5 mm.

[0082] Comparative Example 9

[0083] A method for preparing activated carbon, the specific method steps are as follows, which are partially the same as those in Example 4, except that: (3) the initially activated crushed particles are evenly mixed with a 40% (w / w) phosphoric acid solution which is 35% of the mass of the initially activated crushed particles, and the mixture is first ball-milled at a speed of 330 rpm for 35 min, and then ball-milled for a second time at a speed of 230 rpm for 90 min to obtain ground particles, wherein the ball diameter of the first ball milling is 0.5 mm and the ball diameter of the second ball milling is 1 mm.

[0084] Comparative Example 10

[0085] A method for preparing activated carbon, the specific method steps are as follows, which are partially the same as those in Example 4, except that: (3) the initially activated pulverized particles are evenly mixed with a 40% (w / w) phosphoric acid solution that is 35% of the mass of the initially activated pulverized particles, firstly ball-milled at a speed of 330 rpm for 35 minutes, then pressed at 45 MPa for 35 minutes into sheets, and then broken into particles, and then ball-milled for a second time at a speed of 230 rpm for 90 minutes to obtain ground particles, the ball diameter of the first ball milling is 0.5 mm and the ball diameter of the second ball milling is 1 mm.

[0086] Comparative Example 11

[0087] A method for preparing activated carbon, the specific method steps are as follows, which are partially the same as those in Example 4, except that: (3) the initially activated crushed particles are evenly mixed with a 40% (w / w) phosphoric acid solution that is 35% of the mass of the initially activated crushed particles, and then the pressure is quickly increased from 5 MPa to 30 MPa at a rate of 2 to 3 MPa / min, and then slowly increased to 40 MPa at a rate of 0.5 to 1 MPa / min, and then the pressure is maintained for 10 minutes, pressed into tablets, and then broken into particles, and then ball milled at a rate of 230 rpm for 90 minutes to obtain ground particles, and the ball diameter of the ball mill is 1 mm.

[0088] Comparative Example 12

[0089] A method for preparing activated carbon, the specific method steps are as follows, which are partially the same as those in Example 4, except that: (3) the initially activated crushed particles are first ball-milled at a rate of 330 rpm for 35 minutes, then the pressure is rapidly increased from 5 MPa to 30 MPa at a rate of 2 to 3 MPa / min, then slowly increased to 40 MPa at a rate of 0.5 to 1 MPa / min, and the pressure is maintained for 10 minutes, pressed into tablets, and then broken into particles, and then ball-milled for the first time at a rate of 230 rpm for 90 minutes to obtain ground particles, the ball diameter of the first ball milling is 0.5 mm and the ball diameter of the second ball milling is 1 mm.

[0090] Comparative Example 13

[0091] A method for preparing activated carbon, the specific method steps are as follows and are partially the same as those in Example 4, except that: (4) the ground particles are carbonized in a nitrogen atmosphere: first, the temperature is rapidly raised to 890°C at a rate of 15-20°C / min and kept at this temperature for 25 minutes, and then naturally cooled to 30°C to obtain carbonized particles.

[0092] Comparative Example 14

[0093] A method for preparing activated carbon, the specific method steps are as follows and are partially the same as those in Example 4, except that: (4) the ground particles are carbonized under a nitrogen atmosphere: directly placed at 890°C for 30 minutes, and then naturally cooled to 30°C to obtain carbonized particles.

[0094] Comparative Example 15

[0095] A method for preparing activated carbon, the specific method steps are as follows, which are partially the same as those in Example 4, except that: (5) the carbonized particles are immersed in a 40% (w / w) phosphoric acid solution, carbon dioxide gas is introduced and stirred for 42 minutes, and then a second activation is performed in a carbon dioxide atmosphere: directly placed at 640°C for 90 minutes, then naturally cooled to 60°C, washed to neutral, and then vacuum dried at 50°C to obtain activated carbon. The results of testing are shown in Table 1.

[0096] Comparative Example 16

[0097] A method for preparing activated carbon, the specific method steps are as follows, which are partially the same as those in Example 4, except that: (5) the carbonized particles are immersed in a 40% (w / w) phosphoric acid solution, carbon dioxide gas is introduced and stirred for 42 minutes, and then a second activation is performed in a carbon dioxide atmosphere: directly placed at 640°C, then evacuated to -0.05Mpa, and the pressure is maintained for 90 minutes, and then carbon dioxide-water vapor is introduced to increase the pressure to 1.3Mpa and the pressure is maintained and cyclically cooled to 130°C, and then naturally cooled to 60°C, washed to neutral, and then vacuum dried at 50°C to obtain activated carbon. The results of testing are shown in Table 1.

[0098] Comparative Example 17

[0099] A method for preparing activated carbon, the specific method steps are as follows, which are partially the same as those in Example 4, except that: (5) the carbonized particles are immersed in a 40% (w / w) phosphoric acid solution, carbon dioxide gas is introduced and stirred for 42 minutes, and then a second activation is performed in a carbon dioxide atmosphere: first, the temperature is rapidly raised to 640°C at a rate of 15-20 / min, and the pressure is maintained and the temperature is maintained for 90 minutes, then naturally cooled to 60°C, washed to neutral, and then vacuum dried at a temperature of 50°C to obtain activated carbon. The results of testing are shown in Table 1.

[0100] Table 1

[0101]

[0102] From Table 1 above, it can be found that the preparation method of the present invention, through the process of preliminary activation-pressing and grinding-carbonization-secondary activation, the activated carbon of Examples 1 to 7 has high strength and concentrated pore size distribution characteristics; more specifically: compared with Example 4, Comparative Example 1 lacks the initial activation of the crushed particles using hydrogen peroxide, although the compressive strength of the activated carbon is high, the pore size distribution is relatively poor, and the ash content is high; Comparative Example 2 lacks the operation process of grinding-pressing-grinding the initially activated crushed particles, resulting in very low compressive strength of the activated carbon and high ash content; Comparative Example 3 lacks Activating the carbonized carbonized particles results in relatively poor specific surface area and pore size distribution of the activated carbon, and high ash content, which will affect the adsorption effect of the activated carbon; from Comparative Examples 4 to Comparative Examples 7, it is found that during the initial activation process, the initial activation temperature, heating method and temperature change rate will further affect the specific surface area and pore size distribution of the activated carbon. In Example 4, the initial activation temperature, heating method and temperature change rate are more suitable, so that the specific surface area of ​​the activated carbon is increased and the pore size distribution is more concentrated; from Comparative Examples 8 to 11, it is found that during the grinding and pressing process, The combination of grinding and grinding and the pressurization method will further affect the compressive strength of the activated carbon. The combination of grinding and grinding and the pressurization method selected in Example 4 are more suitable, so that the activated carbon has a higher compressive strength; compared with Example 4, Comparative Example 12 does not add additives during the grinding and pressing process, and the specific surface area of ​​the activated carbon obtained is relatively low, the pore size distribution is relatively dispersed, and the ash content is very high; It is found from Comparative Examples 13 and 14 that during the carbonization process, the heating method and the rate of temperature change will further affect the ash content of the activated carbon, and also make the specific surface area relatively low. and the pore size distribution is also relatively dispersed. The heating method and the temperature change rate selected in Example 4 are more suitable, so that the activated carbon has a lower ash content, a better specific surface area, and a more concentrated pore size distribution. It is found from Comparative Examples 15 to 17 that in the secondary activation process, the heating method, the insulation method and the temperature change method have a certain influence on the ash content, specific surface area and pore size distribution of the activated carbon. The heating method, the insulation method and the temperature change method selected in Example 4 are more suitable, so that the activated carbon has a lower ash content, a better specific surface area, and a more concentrated pore size distribution.

[0103] In summary, the activated carbon prepared by the present invention has good pore distribution uniformity and uniform pore size, and also has high strength, which can not only improve the adsorption performance and effect of the activated carbon, but also improve the adsorption efficiency and service life of the activated carbon; in addition, the method for preparing activated carbon of the present invention can use different fruit shell raw materials such as walnut shells, apricot kernels, peach kernels, coconut shells, and date kernels.

[0104] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit and essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0105] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing activated carbon, characterized in that: The following steps are involved: (1) washing the fruit shell with deionized water, vacuum drying, and then crushing to obtain crushed particles; (2) immersing the crushed particles in a hydrogen peroxide solution with a pH value of 5 to 6, stirring at a temperature of 30 to 35° C. for 2 to 3 hours, filtering to remove the liquid, slowly heating to 250 to 280° C. and keeping the temperature for 30 to 45 minutes, then rapidly cooling to 50 to 60° C., washing, and vacuum drying to obtain preliminarily activated crushed particles; (3) mixing the initially activated crushed particles with the phosphoric acid solution, first performing a first ball milling, then pressing into sheets by first rapidly increasing the pressure, then slowly increasing the pressure, and then maintaining the pressure, and finally breaking them into particles, and then performing a second ball milling to obtain ground particles; (4) carbonizing the ground particles in a nitrogen atmosphere: first, rapidly heating to 850-900° C. and keeping the temperature for 25-30 min, then slowly cooling to 150-180° C., and then naturally cooling to 30-35° C. to obtain carbonized particles; (5) The carbonized particles are immersed in a phosphoric acid solution, and carbon dioxide gas is introduced and stirred for 40 to 45 minutes, and then a second activation is performed in a carbon dioxide atmosphere: first, the temperature is rapidly raised to 620 to 650°C, and then vacuumized and the pressure is maintained for 90 to 120 minutes. Then, carbon dioxide-water vapor is introduced to increase the pressure and the pressure is maintained for a cycle cooling to 120 to 130°C, and then naturally cooled to 50 to 60°C, washed to neutrality, and vacuum dried to obtain activated carbon.

2. A method for preparing activated carbon according to claim 1, characterized in that: In step (2), the rate of slow heating is 1-2°C / min; the rate of rapid cooling is 5-8°C / min.

3. A method for preparing activated carbon according to claim 1, characterized in that: In step (3), the ball diameters of the first ball milling and the second ball milling are both 0.5 to 1 mm.

4. A method for preparing activated carbon according to claim 1, characterized in that: In step (3), the first ball milling: the ball milling rate is 300-350 rpm, and the ball milling time is 30-40 min; the second ball milling: the ball milling rate is 200-250 rpm, and the ball milling time is 90-100 min.

5. A method for preparing activated carbon according to claim 1, characterized in that: In step (3), the pressure for tableting is rapidly increased from 5 MPa to 25-30 MPa at a rate of 2-3 MPa / min, then slowly increased to 40-45 MPa at a rate of 0.5-1 MPa / min, and then maintained at this pressure for 10-15 min.

6. A method for preparing activated carbon according to claim 1, characterized in that: In step (4), the rapid heating rate is 5 to 10°C / min; the slow cooling rate is 1 to 2°C / min.

7. A method for preparing activated carbon according to claim 1, characterized in that: In step (5), the rate of rapid heating is 15-20°C / min.

8. A method for preparing activated carbon according to claim 1, characterized in that: In step (5), the pressure is evacuated to -0.06 to -0.04 MPa and the pressure is increased to 1.2 to 1.4 MPa.

9. A method for preparing activated carbon according to claim 1, characterized in that: In step (1), the particle size of the crushed particles is 2 to 3 mm; and the fruit shell is one of peach kernel, coconut shell, walnut kernel, apricot kernel or jujube kernel.

10. A method for preparing activated carbon according to claim 1, characterized in that: In step (4), in steps (1), (2) and (5), the vacuum drying temperature is 40 to 50°C.

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