CN114768767A

CN114768767A - Activated carbon prepared from waste biomass furnace slag, and preparation method and application thereof

Info

Publication number: CN114768767A
Application number: CN202210575112.4A
Authority: CN
Inventors: 罗倚坪; 唐俊杰; 赵治臣; 曾莉莎
Original assignee: Chengdu Lantau Blue Environmental Protection Technology Co ltd
Current assignee: Chengdu Lantau Blue Environmental Protection Technology Co ltd
Priority date: 2022-05-25
Filing date: 2022-05-25
Publication date: 2022-07-22

Abstract

The invention belongs to the field of environmental engineering, and particularly relates to activated carbon prepared from waste biomass furnace slag, a preparation method and application thereof. The specific technical scheme is as follows: an activated carbon is prepared from biomass through high-temp calcining twice at least. The invention provides a novel method for preparing activated carbon. The biomass furnace slag is used as a raw material, the water vapor is used as a single activating agent, the method is more environment-friendly than a chemical activation method for preparing the activated carbon, only the furnace slag and the water vapor are needed to be used in the preparation process, no chemical activating agent is needed to be added, no protective gas is needed to be introduced, the furnace slag is not needed to be pretreated, the obtained activated carbon has excellent adsorption performance, and the method has huge application prospect and popularization value.

Description

Activated carbon prepared from waste biomass furnace slag, and preparation method and application thereof

Technical Field

The invention belongs to the field of environmental engineering, and particularly relates to activated carbon prepared from waste biomass furnace slag, a preparation method and application thereof.

Background

With the continuous and rapid development of economy, the problems of energy crisis and environmental pollution are becoming more serious, and the development of renewable energy is concerned by more and more researchers. Among all renewable energy sources, biomass is a carbon-based renewable energy source, abundant in reserves, and environmentally friendly.

The biomass power plant can generate a large amount of slag in the power generation process, is a carbon-containing resource with huge potential, and unfortunately, the high-quality resource is not well utilized. If it can be effectively used, not only can the resource be recycled, but also the environmental problem caused by the waste discharge can be relieved. The waste biomass furnace slag is used as the raw material to prepare the active carbon, so that the carbonization step can be omitted, the energy consumption is saved, and the cost is reduced. Although some methods for preparing activated carbon by using fly ash slag and the like exist at present, raw materials and biomass slag have great difference, the existing methods all need to be pretreated by acid-alkali liquor, added with chemical activating agents, introduced with protective gas and the like, the operation is complicated, the cost is high, and the added acid-alkali liquor, chemical activating agents and the like can cause new environmental problems.

Therefore, a method which is environment-friendly, simple to operate and capable of efficiently converting waste biomass slag into activated carbon with excellent adsorption performance is urgently needed.

Disclosure of Invention

The invention aims to provide activated carbon prepared from waste biomass slag, and a preparation method and application thereof.

In order to realize the purpose of the invention, the technical scheme adopted by the invention is as follows: an activated carbon is obtained by carrying out high-temperature calcination on a biomass material at least twice.

Preferably, the second high temperature calcination is carried out while continuously introducing steam.

Preferably, the first high temperature calcination is carried out in a dry environment.

Correspondingly, the method for preparing the activated carbon comprises the following steps: and calcining the biomass material at high temperature in a dry environment to obtain slag, and calcining the slag at high temperature again in a steam environment.

Preferably, the method comprises the steps of:

(1) crushing the biomass, and calcining at 600-900 ℃ for 0.5-2 h to obtain furnace slag;

(2) and (3) crushing the furnace slag, sieving the crushed furnace slag by a sieve of 20-200 meshes, introducing water vapor, raising the temperature from room temperature to a target temperature at a speed of 2.5-10 ℃/min, wherein the target temperature is 500-900 ℃, and preserving the temperature for 0.5-2 h.

Preferably, the flow rate of the introduced water vapor is as follows: 4-600 mL/min.

Preferably, in step (1), the calcination temperature is 800 ℃.

Preferably, in step (2), the target temperature is 800 ℃.

Preferably, in the step (2), the holding time is 1 h.

Preferably, in the step (2), the temperature increase rate is 5 ℃/min.

The invention has the following beneficial effects: the invention provides a novel method for preparing activated carbon. The biomass furnace slag is used as a raw material, the steam is used as a single activating agent, the method is more environment-friendly than a chemical activation method for preparing the activated carbon, only the furnace slag and the steam need to be used in the preparation process, no chemical activating agent needs to be added, no protective gas needs to be introduced, no pretreatment is needed to be carried out on the furnace slag, the obtained activated carbon has excellent adsorption performance, and the method has huge application prospect and popularization value.

Drawings

FIG. 1 is an electron microscope scan of a waste biomass slag of the present invention;

FIG. 2 is an electron microscope scan of activated carbon prepared from waste biomass slag under nitrogen;

FIG. 3 is an electron microscope scan of activated carbon prepared using the method of the present invention.

Detailed Description

The invention provides activated carbon prepared from waste biomass slag. The preparation method comprises the following steps:

(1) crushing the waste biomass, and calcining at 600-900 ℃ for 0.5-2 h, preferably at 800-900 ℃ for 40-60 min. Calcining until the waste biomass is residue to obtain waste biomass slag.

(2) Crushing the furnace slag, sieving the crushed furnace slag by a 20-200-mesh sieve, placing the crushed furnace slag in a tubular furnace, taking water vapor as an active agent (the flow rate of the water vapor is 4-600 mL/min), raising the temperature from room temperature to 500-900 ℃ at the speed of 2.5-10 ℃/min, and activating for 0.5-2 h. Thus obtaining the active carbon. The preferred activation temperature is 800 ℃ and the preferred activation time is 1 h. In the activation process of the slag, only water vapor is added as an activator, no chemical activator is additionally added, and protective gas such as nitrogen is not used.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. The obtained data are average values obtained after at least 3 repetitions are performed, and each repetition is obtained as valid data.

The first embodiment is as follows: pretreatment combined chemical activator for preparing activated carbon under different conditions

1. And preparing waste biomass furnace slag. The waste biomass slag used in the examples of the present invention was obtained from a biomass power plant of Mianyang city, Sichuan province by burning mixed biomass (75 wt% wood, 15 wt% straw and 10 wt% bark) at a high temperature of 800 ℃ for 1 hour, unless otherwise specified. Before use, the waste biomass furnace slag is washed by water to remove surface impurities, is dried at 105 ℃ after being filtered, and is crushed and sieved by a sieve of 20-200 meshes. The waste biomass slag was determined to contain 4.52 wt% moisture, 13.57 wt% volatiles, 10.41 wt% ash, 71.50 wt% fixed carbon. And judging the adsorption performance of the waste biomass slag raw material and the prepared active carbon by using the iodine adsorption value. The iodine adsorption value of the waste biomass slag raw material is 193.89 mg/g. An electron microscope scan of the waste biomass slag is shown in fig. 1. The inventor utilizes the slag with different meshes to respectively prepare the activated carbon, and the difference of the adsorption performance is not large, so that the subsequent examples do not independently show the related experiments of the influence of the meshes on the performance of the activated carbon.

2. Pretreatment of furnace slag for preparing activated carbonThe impact of performance. After the waste biomass slag is prepared according to the step 1, 3mol/L NaOH solution is used for dipping treatment for 5 hours at 105 ℃, and the solid-to-liquid ratio of the NaOH solution to the slag is 20:3(200mL of NaOH solution is used for dipping 30g of slag). After NaOH impregnation, the filtrate was washed with water until neutral and dried at 105 ℃ to obtain NaOH impregnated slag with adsorption properties shown in group 1 of table 1. With N₂For shielding gas, the slag obtained after NaOH pretreatment is directly activated at a target temperature for 2h (from room temperature, the temperature is gradually increased to the target temperature at the speed of 5 ℃/min), and activated carbon is prepared, wherein the performance of each activated carbon is shown in a group 2 and a group 3 in a table 1. It should be noted that: without special mention, N₂The whole-course introducing mode is adopted when the protective gas is adopted (namely, the temperature of the tubular furnace is increased, and the temperature of the tubular furnace is reduced).

TABLE 1 influence of NaOH pretreatment on iodine adsorption value of activated carbon samples

Group of	N₂	Target temperature	Time of heat preservation	Iodine adsorption number
					Group 1	\	\	\	279.13mg/g
Group
	2	30mL/min	500℃	2h	248.76mg/g
Group
	3	30mL/min	800℃	2h	290.25mg/g

The results in table 1 show that compared with the iodine adsorption value (193.89mg/g) of the waste biomass slag raw material, the iodine adsorption value of the slag obtained through NaOH pretreatment is slightly increased, and the iodine adsorption value of the activated carbon cannot be effectively improved through direct high-temperature activation of the slag obtained through NaOH pretreatment.

3. Selecting the waste biomass slag impregnated by the NaOH solution in the step 2, washing the waste biomass slag with water until filtrate is neutral, drying the waste biomass slag at 105 ℃, respectively treating the waste biomass slag at different impregnation ratios by using different chemical active agents (the mass ratio of the active agent to the slag is 2-2.5 g/g), then carrying out ultrasonic treatment (40KHz and 30min), impregnating for 12 hours, drying the waste biomass slag at 105 ℃, and then carrying out N-based drying at 105 DEG₂For protection gas, the activated carbon is respectively activated for 2h at different target temperatures from room temperature (the temperature is gradually increased to the target temperature from the room temperature at the speed of 5 ℃/min), and each group of activated carbon is prepared. The prepared activated carbon was activated with a chemical activator, and a sample of the activated carbon was taken out after the tube furnace was cooled to room temperature. The activated carbon was washed with distilled water until the filtrate was neutral, dried at 105 ℃ and then subjected to iodine adsorption value measurement, the results of which are shown in table 2. A control of waste biomass slag without impregnation with NaOH solution was also set (table 2 group 5).

TABLE 2 Effect of different pretreatment-chemical active agent combinations on iodine adsorption values of activated carbon samples

Group of

Pretreatment of

Active agent

Impregnation ratio

Target temperature

Time of heat preservation

Iodine adsorption number

Group 1

NaOH

H₃PO₄

2.5

800℃

2h

138.37mg/g

Group

2

NaOH

ZnCl

₂

2

800℃

2h

226.62mg/g

Group

3

NaOH

K₂CO₃

2

800℃

2h

403.90mg/g

Group 4

NaOH

KOH

2

800℃

2h

540.64mg/g

Group 5

\

KOH

2

800℃

2h

588.20mg/g

The results show that: different chemical active agents have different effects on the preparation of the activated carbon. The KOH effect is optimal; and the pretreatment with NaOH solution negatively affected the adsorption performance of the activated carbon (group 4 compared to group 5). This is in contrast to the conventional process which requires a pretreatment with NaOH to enhance the performance of the activated carbon.

4. Without NaOH pretreatment (in the subsequent examples, NaOH is not used), the slag is soaked by KOH according to different soaking ratios (the mass ratio of the active agent to the slag is 0.5-3 g/g) and is subjected to ultrasonic treatment (40KHz and 30min) for 12h, then the slag is dried at 105 ℃, 4g of the slag after being treated by the chemical active agent is placed into a tube furnace, and N is used for N₂And (3) gradually raising the temperature to the target temperature at the speed of 5 ℃/min from the room temperature for protective gas, and keeping the temperature for 0.5-3 h. After activation, the solution is washed to be neutral by distilled water, and the iodine adsorption value is measured after drying at 105 ℃. The target temperature and iodine adsorption value of the activated carbon obtained after the treatment are shown in table 3. "\" indicates that the slag has burned off and no iodine adsorption value.

TABLE 3 comparison of the effects of different reaction conditions on the prepared activated carbon

Group of	Active agent	Impregnation ratio	Target temperature	Time of heat preservation	Iodine adsorption number
						Group 1	KOH	2	400℃	2h	296.22mg/g
Group
	2	KOH	2	500℃	2h	340.50mg/g
Group
	3	KOH	2	600℃	2h	392.42mg/g
Group 4							KOH	2	700℃	2h	463.36mg/g
	Group 5	KOH	2	800℃	1h	579.25mg/g
Group 6							KOH	2	800℃	2h	588.20mg/g
	Group 7	KOH	2	800℃	3h	\
Group 8							KOH	2	900℃	1h	\
	Group 9	KOH	2	600℃	4h	459.63mg/g
Group 10							KOH	2	700℃	4h	546.34mg/g
	Group 11	KOH	2	700℃	3h	543.77mg/g
Group 12							KOH	2	700℃	1h	559.47mg/g
	Group 13	KOH	2	700℃	0.5h	543.77mg/g
Group 14							KOH	0.5	800℃	1h	411.95mg/g
	Group 15	KOH	1	800℃	1h	408.97mg/g
Group 16							KOH	1.5	800℃	1h	461.68mg/g
	Group 17	KOH	3	800℃	1h	579.25mg/g

The results according to table 3 show that: after the waste biomass furnace slag is calcined at 800 ℃ (namely the waste biomass is changed into furnace slag at 800 ℃), the surface structure is completely hardened. The lower temperature activation condition can not realize the purpose of hole expansion, while the higher activation temperature can lead the slag to be completely burnt into ash and can not form active carbon, so 800 ℃ is selected as the optimal activation temperature. Increasing the activation time is beneficial to increasing the performance of the activated carbon, but too long activation time can cause the slag to be burnt to ash, the iodine adsorption values of 1h and 2h of activation time are not greatly different, and the yield is higher when the activation time is 1h, so 1h is selected as the activation time. The iodine adsorption value is gradually increased with the increase of the dosage of the activating agent, but the use of a chemical agent with an excessively high content not only increases the cost, but also causes more environmental pollution. Thus, in the alternative, it is recommended not to use a chemical activator alone or, preferably, not.

The second embodiment: effect of chemical Agents coupled with steam on activated carbon preparation

1. The effect of the protective gas. Without using chemical activator, 4g of waste biomass slag was placed in a tube furnace, and the presence or absence of protective gas N was examined under the condition that water vapor was continuously introduced at a flow rate of 200mL/min₂Influence on the performance of the prepared activated carbon. At the same time, only N is introduced₂For the purpose of protecting gas, the adsorption performance of activated carbon prepared without introducing steam for activation was used as a comparison. The tube furnace was started from room temperature and gradually warmed up to 800 ℃ at a rate of 5 ℃/min and held for 1 h. After the reaction is finished, stopping introducing the water vapor when the tubular furnace is cooled to 200 ℃. It should be noted that: in this example, the introduction of water vapour is only started when the tube furnace is heated to 100 ℃ in order to ensure that the introduction of water vapour is completely in gaseous form. During the cooling stage, the water vapor is continuously introduced to enhance the activation capability. When the temperature is reduced to below 200 ℃, the water vapor activation capacity is not high, and the condensation phenomenon occurs when the temperature is lower than 100 ℃. In order to ensure that water vapor is present in the tube furnace and has a strong activation capacity and no condensation occurs, the introduction of water vapor is stopped at 200 ℃. And (4) not specifically describing, and stopping introducing the water vapor when the temperature in the tubular furnace is reduced to 200 ℃ after the activation. When the tube furnace is cooled to room temperature, the product is taken out and weighed, and the yield is calculated. The yield is calculated by the formula: the yield of activated carbon (mass of activated carbon/initial mass of slag) × 100%, and the performance of the activated carbon produced was evaluated by the iodine adsorption value. The results are shown in Table 4. Table 4 electron microscopy scans of the activated carbon prepared in group 2 are shown in figure 2.

TABLE 4 comparison table of the effect of the protective gas on the prepared activated carbon

Introducing only protective gas N₂The iodine adsorption value of the prepared activated carbon is lower than that of the activated carbon prepared in the presence of water vapor, which shows that the performance of the activated carbon can be improved by water vapor activation. In the prior art, when the activated carbon is prepared, protective gas such as nitrogen is usually introduced to discharge redundant oxidizing gas generated at high temperature in time so as to prevent the surface structure of the prepared activated carbon from collapsing. However, Table 4 shows that the addition of protective gas under the steam activation conditions does not significantly increase the performance of the activated carbon produced. And consider the introduction of N₂The production cost is increased. Therefore, the following examples without specific description do not consider N₂As a shielding gas.

2. The influence of the manner of introduction of the water vapor. 4g of waste biomass slag is put into a tubular furnace, water vapor with the flow rate of 200mL/min is used as an activating atmosphere, and the influence of the water vapor introduction mode on the adsorption performance of the prepared activated carbon is examined. The tube furnace was started from room temperature and gradually warmed up to 800 ℃ at a rate of 5 ℃/min and held for 1 h. Table 5 set 1 shows that steam was introduced only when the tube furnace reached 100 ℃, while table 5 set 2 shows that steam was introduced when the tube furnace was initially warmed.

TABLE 5 comparison of the effects of steam introduction on the activated carbon prepared

Group of	Steam of water	Water vapor introduction mode	N₂	Iodine adsorption number	Loss on ignition (%)
						Group 1	200mL/min	After the temperature is raised to 100 DEG C	/	608.31mg/g	35.87
Group 2	200mL/min	Initiation of the reaction	/	705.19mg/g	35.77

The results show that the introduction of water vapor was continued from the beginning of the reaction, and activated carbon having a higher iodine adsorption value could be obtained. The possible reasons are: although the tubular furnace wall contains small water drops in the initial stage of the reaction, the water drops can be gasified to generate steam as the temperature reaches 105 ℃, so that the activation process is promoted, and the adsorption performance of the prepared activated carbon is improved. Therefore, in the following examples, which are not specifically described, steam was introduced at the initial stage of the reaction.

3. The effect of the addition of the chemical active on the activation by water vapor. 4g of waste biomass slag was placed in a tube furnace, chemical activators of different impregnation ratios were added as shown in Table 6, and subjected to ultrasonic treatment (40KHz, 30min) for 12 hours, followed by drying at 105 ℃. And continuously introducing water vapor with the flow rate of 200mL/min from the beginning of the reaction, gradually heating to 800 ℃ from the room temperature in the tubular furnace at the speed of 5 ℃/min, and keeping for 1 h. After the reaction is finished, stopping introducing the water vapor when the tubular furnace is cooled to 200 ℃. Using chemical activator, washing activated carbon with distilled water after activation till the filtrate is neutral, drying at 105 deg.C, and measuring iodine adsorption value. The results are shown in Table 6.

TABLE 6 comparison of the effects of different active agents on the activated carbon produced

The results show that: the general activated carbon activation and preparation method is not suitable for waste biomass furnace slag, and when a chemical active agent and steam are used in a combined manner, the adsorption effect of the prepared activated carbon is not ideal, and the activated carbon with excellent performance can be prepared only under the condition of pure steam.

Example three: influence of other reaction parameters on the preparation of activated carbon

1. The effect of the water vapor flow. At N₂30mL/min (N is introduced during the heating and cooling stages₂As protective gas, N is not introduced in the heat preservation stage₂) In this case, the flow rate of steam was adjusted (steam was started to flow only after the temperature of the tube furnace reached 100 ℃), and the parameters and results were as shown in Table 7. At the same time, the comparison has no N₂As a protective gas, steam was introduced at the beginning of the reaction, and the effect of changing the flow rate of steam on the production of activated carbon was as shown in Table 8. The other reaction conditions were the same as those in Table 5 and group 2 of example 2 (the temperature in the tube furnace was gradually increased from room temperature to 800 ℃ at a rate of 5 ℃/min, and the temperature was maintained for 1 hour; after the reaction was completed, the introduction of steam was stopped when the tube furnace was cooled to 200 ℃). Table 8 the electron micrograph of group 3 is shown in figure 3.

TABLE 7 comparison table of the effect of steam flow on the prepared activated carbon

Group of

Steam vapor

Water vapor introduction mode

N₂

N₂Introduction mode

Iodine adsorption number

Loss on ignition

Group 1

5mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

411.42mg/g

12.89％

Group 2

10mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

419.22mg/g

14.30％

Group 3

15mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

428.42mg/g

14.82％

Group 4

30mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

449.22mg/g

15.02％

Group 5

45mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

516.24mg/g

18.24％

Group 6

60mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

598.00mg/g

24.63％

Group 7

90mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

624.44mg/g

23.41％

Group 8

120mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

672.62mg/g

28.24％

Group 9

150mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

658.59mg/g

29.14％

Group 10

250mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

722.02mg/g

36.15％

Group 11

300mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

778.65mg/g

41.14％

Group 12

400mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

740.92mg/g

42.93％

Group 13

500mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

770.24mg/g

47.24％

Group 14

600mL/min

After the temperature is raised to 100 DEG C

30mL/min

Temperature rising and falling stage

800.15mg/g

47.69％

TABLE 8 comparison of the effects of steam flow on the activated carbon produced

Group of	Steam vapor	Introduction mode	N₂	Iodine adsorption number	Loss on ignition
						Group 1	300mL/min	Initiation of the reaction	/	739.86mg/g	41.14％
Group
	2	400mL/min	Initiation of the reaction	/	774.69mg/g	42.93％
Group
	3	500mL/min	Initiation of the reaction	/	817.42mg/g	47.24％
Group 4							600mL/min	Initiation of the reaction	/	782.09mg/g	47.69％

The results show that:with N₂When the protective gas is used, the performance of the prepared activated carbon is gradually increased along with the increase of the flow of the water vapor. However, when there is no N₂When the protective gas is used, the performance of the prepared activated carbon is gradually increased along with the increase of the flow of the water vapor. However, when the flow rate of water vapor exceeds 500mL/min, the performance of the activated carbon begins to decline. This may be because there is no N₂To protect the gas, excess water vapor causes the pore-like structure of the activated carbon surface to begin to collapse.

2. Influence of reaction parameters. The activation temperature, time, and rate of temperature rise were adjusted as in Table 9, and the rest of the conditions were the same as in Table 8 and set 3 of step 1 of this example. The results are shown in Table 9.

TABLE 9 temperature Effect on activated carbon prepared

Group of	Activation temperature	Time of activation	Rate of temperature rise	Iodine adsorption number	Loss on ignition (%)
						Group 1	500℃	1h	5℃/min	270.90mg/g	9.91
Group 2	600℃	1h	5℃/min	312.88mg/g	6.80
						Group 3	700℃	1h	5℃/min	495.23mg/g	17.76
Group 4	900℃	1h	5℃/min	\	\
						Group 5	800℃	0.5h	5℃/min	603.09mg/g	29.27
Group 6	800℃	1.5h	5℃/min	794.66mg/g	50.82
						Group 7	800℃	2h	5℃/min	717.40mg/g	61.39
Group 8	800℃	1h	2.5℃/min	632.96mg/g	38.47
						Group 9	800℃	1h	7.5℃/min	681.73mg/g	42.02
Group 10	800℃	1h	10℃/min	678.01mg/g	37.87

The results show that: the aim of reaming cannot be achieved at a lower activation temperature, and all the waste biomass furnace slag is changed into ash when the temperature reaches 900 ℃; 800 ℃ is the optimum activation temperature. In addition, the activation time, the temperature rise rate, and the like also have a significant influence on the performance of the produced activated carbon.

4. The influence of different raw materials. The raw materials used in this example were: pure corn stalk slag, pure miscellaneous wood (i.e., various types of wood) slag, and corn stalk. Wherein, the preparation methods of the corn straw slag and the miscellaneous tree slag are all obtained by high-temperature calcination. The corn stalk is dried corn stalk without calcination treatment. The respective slags and corn stover were used to prepare activated carbon according to group 3 of Table 8, and the results are shown in Table 10.

TABLE 10 comparison of the effects of different raw materials on the prepared activated carbon

Group of	Raw material	Steam of water	Steam introduction mode	Iodine adsorption number	Loss on ignition (%)
						Group 1	Corn stalk slag	500mL/min	Initiation of the reaction	635.17mg/g	63.21
Group 2	Miscellaneous tree furnace slag	500mL/min	Initiation of the reaction	595.32mg/g	48.11
						Group 3	Corn stalk	500mL/min	Initiation of the reaction	\	\

The results show that: the corn stalks are directly burned into ash under the high-temperature environment with steam, the slag is firstly calcined under the high temperature under the dry environment and then calcined under the steam environment, and the produced activated carbon is activated carbon.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various changes, modifications, alterations, and substitutions which may be made by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. An activated carbon characterized by: the biomass material is obtained by carrying out high-temperature calcination on the biomass material at least twice.

2. The activated carbon according to claim 1, wherein: and continuously introducing water vapor during the second high-temperature calcination.

3. The activated carbon according to claim 1 or 2, characterized in that: the first high temperature calcination is carried out in a dry environment.

4. A method for producing the activated carbon according to any one of claims 1 to 3, characterized in that: the method comprises the following steps: and calcining the biomass material at high temperature in a dry environment to obtain slag, and calcining the slag at high temperature again in a steam environment.

5. The method of claim 4, further comprising: the method comprises the following steps:

(1) crushing biomass, and calcining at 600-900 ℃ for 0.5-2 h to obtain furnace slag;

(2) crushing the furnace slag, sieving the crushed furnace slag by a sieve of 20-200 meshes, introducing water vapor, raising the temperature from room temperature to a target temperature at the speed of 2.5-10 ℃/min, wherein the target temperature is 500-900 ℃, and preserving the temperature for 0.5-2 h.

6. The method of claim 5, further comprising: the flow of the introduced water vapor is as follows: 4-600 mL/min.

7. The method of claim 5, further comprising: in the step (1), the calcination temperature is 800 ℃.

8. The method of claim 5, wherein: in step (2), the target temperature is 800 ℃.

9. The method of claim 5, wherein: in the step (2), the heat preservation time is 1 h.

10. The method of claim 5, further comprising: in the step (2), the heating rate is 5 ℃/min.