CN108117074B

CN108117074B - Preparation method of super activated carbon and method for recycling produced waste liquid and producing by-product carbonate

Info

Publication number: CN108117074B
Application number: CN201611064672.4A
Authority: CN
Inventors: 潘军青; 程杰; 杨裕生; 孙艳芝
Original assignee: Beijing University of Chemical Technology
Current assignee: Beijing University of Chemical Technology
Priority date: 2016-11-28
Filing date: 2016-11-28
Publication date: 2020-04-28
Anticipated expiration: 2036-11-28
Also published as: CN108117074A

Abstract

The invention relates to the field of biomaterial processing, energy materials and environmental protection, and discloses a preparation method of super activated carbon and a method for recycling produced waste liquid and producing a byproduct of carbonate. The preparation method of the super activated carbon comprises the following steps: contacting the carbonaceous material with an oxidizing agent and a hydrated alkaline activator under vacuum conditions to immerse the oxidizing agent and the hydrated alkaline activator into the carbonaceous material; subjecting the carbonaceous material immersed with the oxidizing agent and the hydrated alkaline activator to a first heat treatment to activate the carbonaceous material and obtain carbon dioxide gas; and cooling, washing and drying the obtained activated carbonaceous material to obtain the super activated carbon and carbon dioxide gas. The waste liquid produced by the process is treated under different pH values so as to realize the recovery of byproducts and the recycling of the waste liquid. By the method, the product yield can be effectively improved, the waste liquid is recycled, the by-product is recycled, the energy is saved, the environment is protected, and the social, environmental and economic benefits are remarkable.

Description

Preparation method of super activated carbon and method for recycling produced waste liquid and producing by-product carbonate

Technical Field

The invention relates to the field of biomaterial processing, energy materials and environmental protection, in particular to a preparation method of super activated carbon and a method for recycling waste liquid produced by a preparation process of the super activated carbon and producing a byproduct of carbonate.

Background

Natural plant materials, such as straws, wood and other biological materials are subjected to a high-temperature carbonization process to obtain the activated carbon with a high specific surface, and the activated carbon is widely applied to the traditional fields of food, chemical industry, water, air purification and the like. In recent years, it has been found that activated carbon having a higher specific surface area can be obtained from shells such as coconut shells, peach shells and apricot shells through carbonization and activation processes, and the activated carbon is generally called as high-grade activated carbon. Generally, the specific surface of the prior shell carbon activated by water vapor, air and carbon dioxide can reach 700-1100m²The activated carbon with high specific surface area has strong adsorption capacity, is widely used for indoor air purification, colored noble metal adsorption recovery, biological medicine carrier and the like, and has relative requirementsHigher field.

In order to further improve the specific surface area and the related adsorption performance of the carbon material, a great number of researchers have developed the chemical activation process research of the carbon-containing raw materials such as shell carbon, petroleum coke and the like, and the preparation process of the activated carbon with the ultrahigh specific surface area is mainly based on chemical activation at present. Common chemical activators include hydroxides of alkali metals and alkaline earth metals (CN01126708.9, CN00107740.6), inorganic salts and inorganic acids, wherein the performance of the super activated carbon prepared by using KOH as an activator is the most excellent, and the common ratio of alkali to carbon is generally 3-8:1 (coal conversion, Vol.24, No.2, 2001, 4: 29). For example, the early US patent 4082694 is to mix petroleum coke with 3 times weight of KOH, then to perform dehydration pre-activation at the temperature of 300-500 ℃, then to perform activation at the temperature of 700-1000 ℃, then to cool and fully wash, so as to obtain a product with a specific surface area of 2600m²Per gram of super activated carbon; chinese patent CN105948042A reports that biological carbon materials and potassium hydroxide are chemically activated under the action of ultrasound and vibration to obtain the super activated carbon required by a super capacitor. CN105923634A also reports that coconut shell carbon and KOH are roasted at a ratio of 1:2 to 1:5 at a temperature of 800-850 ℃ to obtain a super activated carbon material. CN105384169A also reports that high temperature activation roasting of carbonaceous material after KOH impregnation yields super activated carbon. CN105948042A also newly discloses that biomass materials such as coconut shells and straws are soaked in KOH solution, and the special super activated carbon for the super capacitor is obtained through ultrasonic dispersion and stirring and then high-temperature activation. From the number of patent applications in recent years, the KOH activation process is a very hot field of research. Relatively speaking, NaOH has relatively weak alkalinity and diffusivity, and relatively few studies on its activation are performed, for example, CN104276571A reports that a carbon-containing material and NaOH or zinc sulfate are calcined at a temperature of 500-800 ℃ to obtain a super activated carbon material, and relatively few studies on its electrochemical characteristics are performed.

KOH, which is an alkali metal hydroxide more alkaline than NaOH, has a strong corrosive effect at high temperature, even corrodes carbon materials, and creates many new inner holes in the carbon materials, thereby further improving the specific surface of the activated carbon. When the specific surface area of the activated carbon reachesTo 1500-²In the case of/g, this activated carbon with a high specific surface area is generally referred to as superactive carbon.

In recent years, it has been found that the super activated carbon has a high adsorption effect on not only gas and floating dust but also ions in a solution, so that the super activated carbon is not only used on original medicine and catalyst carriers, but also its super capacitance characteristic is recommended to be used for manufacturing super capacitors, lead carbon batteries and the like. The super activated carbon is used as a key energy storage material of a super capacitor and a lead carbon start-stop battery, can be used for absorbing recovered energy in a braking process and releasing the recovered energy in a starting process, plays roles in recovering energy, assisting starting and prolonging the service life of the battery, and has positive effects in the aspects of reducing fuel consumption, reducing tail gas emission of fuel vehicles and the like.

Since most manufacturers use KOH as an activator, the associated contamination mainly includes:

(1) because KOH has strong corrosivity, alkali steam, alkali fog and alkali spray generated in the high-temperature production process also have strong corrosive action on the respiratory tract of staff and equipment thereof, and the health of the staff is directly influenced.

(2) After the activation is finished, a large amount of alkali metal carbonate and alkaline waste liquid of residual KOH are generated during the washing of the activated carbon, the concentration is high, the alkalinity is strong, and the direct discharge also can seriously pollute the environment. If the method of acid neutralization is adopted for treatment (novel carbon materials, Vol.14, No.2, 1999.6), the acid consumption is large, the cost is high, the material waste is caused, and the method is not suitable for large-scale production.

(3) Because the specific surface of the super activated carbon is high and has strong adsorption capacity to ions, metal ion impurities adsorbed in micropores of the super activated carbon are difficult to be brought out by purified water, and generally, the washing process of the super activated carbon not only needs to consume a large amount of purified water, but also needs a week of washing time, so that the post-treatment and labor cost are high.

These reasons cause that the price of super activated carbon prepared by alkali activation in China is as high as 20-35 ten thousand yuan per ton, and the cost of labor is high in some korea and japan, the yield of super activated carbon activated by KOH is as high as 72 ten thousand yuan per ton, and in addition, the yield of super activated carbon prepared by the prior art is generally 30-40% and can only reach 50% at most, which causes the cost of super activated carbon to be high. The application of super activated carbon in the fields of super capacitors and lead carbon start-stop batteries is directly influenced by the expensive price and the heavy environmental pressure.

Unfortunately, the chemical activation process generates a large amount of acid-containing or alkali-containing industrial waste liquid in the process of preparing the super activated carbon, which is always a difficult problem in the production process of the super activated carbon. The applicant has investigated a number of activated carbon manufacturers over the last few years and has inevitably found that a large amount of purified water is consumed in the production process to clean super activated carbon, and that these strongly alkaline activation waste water and washing waste water have been environmental problems.

Compared with hundreds of preparation processes related to super activated carbon, the treatment technology in the aspect of super activated carbon production waste liquid is always a place ignored by many researchers, and relevant data are rarely reported. At present, few relevant documents are examined, for example, granted patent, ZL201110386303.8 mentions that the post-treatment process of the low-ash super activated carbon mainly focuses on cleaning by using hydrothermal technology and using a large amount of alkali, acid and water, and no report is made about the recycling of production waste liquid and washing waste liquid, particularly recycling. Granted patent ZL201310521208.3 is a pretreatment process of raw materials in the preparation process of super activated carbon, wherein the process refers to soaking a carbon precursor for 2-24 hours by using a mixture of sulfuric acid, persulfate and phosphorus pentoxide to improve the reaction effect of the material. Patent CN102874804A discloses that in order to improve the cleaning effect of activated carbon, the precipitation process of super activated carbon in a leveling tank and the acid cleaning process of adding sulfuric acid and hydrochloric acid are studied. The invention shortens the washing time, but has no effective treatment scheme for the production waste liquid and the recycling of the washing waste liquid. Granted patent ZL201010588664.6 discloses a method for recovering KOH in super activated carbon by using water dissolution using KOH activation process. In fact, the invention also mentions in the specification that the KOH activation process is a process in which carbon reacts with KOH to form potassium carbonate and potassium oxide. Unfortunately, this invention does not consider the recovery of potassium carbonate, the major by-product of the activation waste stream.

Therefore, there is a need to develop a method for preparing super activated carbon with less pollution and high yield, and effectively recycling the process waste liquid produced in the super activated carbon preparation process and recovering the by-products.

Disclosure of Invention

The invention aims to overcome the defects, provides a preparation method of super activated carbon with low pollution and high yield, and also provides a method capable of effectively recycling waste liquid produced in the preparation process of the super activated carbon and recovering byproducts.

In order to achieve the above objects, in one aspect, the present invention provides a method for preparing super activated carbon, wherein the method comprises:

(1) contacting a carbonaceous material with an oxidizing agent and a hydrated alkaline activator under vacuum conditions such that the oxidizing agent and the hydrated alkaline activator are impregnated into the carbonaceous material;

(2) subjecting a carbonaceous material immersed with an oxidizing agent and a hydrated alkaline activator to a first heat treatment to activate the carbonaceous material and obtain carbon dioxide gas;

(3) and (3) cooling, washing and drying the activated carbonaceous material obtained in the step (2) to obtain a super activated carbon product and carbon dioxide gas.

Preferably, the method of contacting the carbonaceous material with the oxidizing agent and the hydrated alkaline activator in step (1) comprises:

(11) under the vacuum condition, a carbonaceous material is contacted with an oxidant so that the oxidant is immersed into the carbonaceous material, and then the carbonaceous material immersed with the oxidant is subjected to a heat treatment B so that the carbonaceous material is subjected to a first activation and carbon dioxide gas is obtained;

(12) contacting a first activated carbonaceous material with a hydrated alkaline activator under vacuum conditions to impregnate the hydrated alkaline activator into the first activated carbonaceous material, and then subjecting the first activated carbonaceous material impregnated with the hydrated alkaline activator to a first heat treatment under an inert gas atmosphere or a reducing gas atmosphere;

preferably, the contacting conditions include: the contact temperature is 80-300 deg.C, and the contact time is 0.5-180 min;

preferably, the hydrated alkaline activator comprises hydrated sodium hydroxide; preferably, the hydrated alkaline activator further comprises a co-activator.

Preferably, in the step (3), the washing step includes:

(31) adding water to the activated carbonaceous material for a first dissolution leaching and performing a solid-liquid separation to obtain an activated mother liquor a and a solid phase a, wherein the amount of water is such that the remaining hydrated alkaline activator can be selectively dissolution leached;

preferably, the step further comprises supplementing an alkaline activator to the activation mother liquor A to obtain the hydrated alkaline activator, and returning to the step (2) for recycling;

(32) adding water and carbon dioxide into the solid phase A obtained in the step (31) for second dissolution leaching, and performing solid-liquid separation to obtain carbonate mother liquor B and activated carbon slurry;

preferably, the water and the carbon dioxide are used in such an amount that carbonate crystals do not precipitate in the system;

preferably, the carbon dioxide used in this step is carbon dioxide generated by the above super activated carbon preparation method;

(33) and carrying out multi-stage water washing and acidification treatment on the activated carbon slurry.

Preferably, in the step (3), the drying includes:

and C, heat treatment: the temperature is 150 ℃ and 500 ℃, and the time is 10-300 min;

and (4) heat treatment D: the temperature is 400 ℃ and 1500 ℃, and the time is 10-500 min.

In a second aspect, the invention provides a method for recycling waste liquid produced in a super activated carbon preparation process and producing carbonate as a byproduct, wherein the method comprises the following steps:

(1) introducing carbon dioxide into the carbonate mother liquor B obtained in the above way at a first alkaline pH value, and carrying out solid-liquid separation, wherein the first alkaline pH value enables byproducts of hydrated silicon dioxide and carbonate mother liquor C to be obtained, and simultaneously carbonate crystals are not separated out;

(2) under a second alkaline pH value, introducing carbon dioxide into the carbonate mother liquor C, freezing, and then carrying out solid-liquid separation to obtain a byproduct carbonate crystal and a crystallization mother liquor D;

preferably, the second alkaline pH value ensures that no bicarbonate crystals are separated out from the system;

(3) introducing carbon dioxide into the crystallization mother liquor D at a third pH value, and carrying out solid-liquid separation to obtain a byproduct bicarbonate crystal and a crystallization mother liquor E;

preferably, the crystallization mother liquor E is returned as water and carbon dioxide to the solid phase a obtained in step (31) as in step (32) above; wherein the third pH value enables the water and carbon dioxide content in the obtained crystallization mother liquor E to meet the requirements of the water and carbon dioxide dosage in the step (32);

preferably, the carbon dioxide used in steps (1) to (3) is carbon dioxide produced by the above-described super activated carbon production method.

Preferably, the first basic pH is greater than a second basic pH, which is greater than a third pH;

preferably, the first alkaline pH is 12.2-13.9; the second alkaline pH value is 10.5-12.1; the third pH value is 3.9-10.4; more preferably, the first alkaline pH is between 12.5 and 13.3; the second alkaline pH value is 10.6-11.3; the third pH value is 4.5-8.2.

In a third aspect, the invention also provides a method for recycling the waste liquid produced in the preparation process of the super activated carbon and producing a byproduct of carbonate, wherein the method comprises the following steps:

(1) adding water into the carbonaceous material activated by the alkaline activator for first dissolution leaching, and performing solid-liquid separation to obtain activated mother liquor A and a solid phase A, wherein the water is used in an amount such that the residual alkaline activator can be selectively dissolved and leached;

preferably, the step also comprises the steps of supplementing an alkaline activator into the activation mother liquor A and returning to the step of recycling in the preparation process of the super activated carbon;

(2) adding water and carbon dioxide into the solid phase A obtained in the step (1) for second dissolution leaching, and performing solid-liquid separation to obtain carbonate mother liquor B and activated carbon slurry;

(3) introducing carbon dioxide into the carbonate mother liquor B obtained in the step (2) at a first alkaline pH value, and carrying out solid-liquid separation, wherein the first alkaline pH value enables byproducts of hydrated silicon dioxide and the carbonate mother liquor C to be obtained, and simultaneously, carbonate crystals are not separated out;

(4) under a second alkaline pH value, introducing carbon dioxide into the carbonate mother liquor C, freezing, and then carrying out solid-liquid separation to obtain a byproduct carbonate crystal and a crystallization mother liquor D;

(5) introducing carbon dioxide into the crystallization mother liquor D at a third pH value, and carrying out solid-liquid separation to obtain a byproduct bicarbonate crystal and a crystallization mother liquor E;

preferably, the crystallization mother liquor E is returned to the step (2) to be added as water and carbon dioxide to the solid phase A; wherein the third pH value enables the water and carbon dioxide content in the obtained crystallization mother liquor E to meet the requirements of the water and carbon dioxide dosage in the step (2);

preferably, the carbon dioxide used in each step is carbon dioxide generated in the above super activated carbon preparation process.

Through the technical scheme, the invention can obtain the following technical effects:

1. in the preparation process of the super activated carbon, a carbonaceous material is contacted with an oxidant and a hydrated alkaline activator under a vacuum condition, the contact condition is controlled to enable the oxidant and the hydrated alkaline activator to be in a flowable state, the oxidant and the hydrated alkaline activator can be effectively immersed into the carbonaceous material, during the heat treatment process, oxidizing substances immersed in micropores of the carbonaceous material are selectively corroded in the pores, the carbonaceous material is partially activated, the immersed hydrated alkaline activator is converted into alkali and water vapor on the surfaces of the pores, and the activation effect of the carbonaceous material is further enhanced through the combined activation of the alkali and the water vapor. After the treatment, the prepared activated carbon material can meet the performance index of the super activated carbon, and the yield is greatly improved.

2, because the hydrated alkaline activator is used in the method, but not the aqueous solution of the alkaline activator, the method greatly reduces the using amount of water, the production cost and the subsequent waste liquid treatment cost while improving the activation effect.

3. Under the preferable conditions, the carbonaceous material is firstly contacted with the oxidant under the vacuum condition and then is subjected to heat treatment, and then is contacted with the hydrated alkaline activator for heat treatment, so that the yield and the specific surface area of the finally prepared super activated carbon can be further improved.

4. Under the preferable conditions, the hydrated alkaline activator uses hydrated sodium hydroxide and is supplemented with a small amount of auxiliary activator, so that the yield of the super activated carbon and the activity of the super activated carbon can be further improved. Meanwhile, the pollution is greatly reduced because a large amount of potassium hydroxide with stronger corrosivity is avoided.

5. Under the optimized conditions, a small amount of water is added into the carbonaceous material activated by the alkaline activator, the solubility of carbonate generated in the preparation process of the super activated carbon is greatly reduced due to the existence of the hydrated alkaline activator in the product, the used water amount just enables the residual hydrated alkaline activator to be just dissolved, so that the hydrated alkaline activator can be effectively separated from the generated carbonate, the obtained hydrated alkaline activator can obtain the reusable hydrated alkaline activator after being supplemented with the corresponding anhydrous alkaline activator, on one hand, the energy is saved, the pollution of the alkaline activator is also reduced, and in addition, the yield of subsequent byproducts can be greatly increased because the carbonate is basically not dissolved. In addition, because a part of water added in the process is converted into crystal water in the crystal sodium carbonate, and the other part of water in the mother liquor can be recycled, the production amount of waste water in the production process is small, and the production cost and the waste liquid treatment cost are greatly reduced.

6. Under the optimized condition, proper amount of water and carbon dioxide are added to treat the solid phase A leached with the alkaline activator, the addition of the carbon dioxide can further convert the unleached alkaline activator into recyclable byproduct carbonate, and simultaneously, the solubility of the carbonate is effectively improved due to the great reduction of the alkaline activator, so that the water amount for dissolving the carbonate can be greatly reduced, and the washing cost and the subsequent waste liquid treatment cost are further reduced. In addition, under more preferable conditions, carbon dioxide generated in the process of preparing the super activated carbon can be used, so that the process by-products can be consumed while being produced, and the requirements of an atomic economic method are met.

7. Under the optimal condition, the alkaline activator and most of the generated carbonate are separated under the combined dissolution action of water and carbon dioxide on the carbonate in the micropores of the product, so that the impurities of metal ions (such as the corresponding metal ions in the alkaline activator) adsorbed in the micropores of the super activated carbon are greatly reduced, and therefore, on one hand, the process is combined with gradient washing, the difficulty in washing the impurities is reduced, and the water quantity can be greatly saved; on the other hand, as most of the alkaline components are separated, the acid amount for neutralization is greatly reduced, the cost is reduced, the discharge of waste liquid is reduced, and the energy-saving and emission-reducing effects are remarkable.

8. Under the optimal conditions, the final drying step adopts two-step heat treatment, in the quick drying process, the pores in the activated carbon can be further opened by the vaporization and impact action of residual moisture, and the conductivity of the activated carbon can be moderately increased.

9. In the processes of recycling waste liquid produced by the preparation process of the super activated carbon and recovering byproducts, the pH value is controlled by stages to treat carbonate mother liquid after the solid phase A of the leached alkaline activator is treated by using a proper amount of water and carbon dioxide, and the carbonate mother liquid is converted into a soluble sodium silicate component in the preparation process of the activated carbon due to the existence of a certain silicon element in a carbonaceous raw material, and the carbon dioxide is introduced under the control of the first alkaline pH value, so that on one hand, the sodium silicate can be hydrolyzed into water-insoluble hydrated silicon dioxide to be separated, and then a white carbon black byproduct is obtained; on the other hand, the introduction of carbon dioxide can further convert the alkaline components in the system into carbonate so as to be beneficial to the next recycling. Experiments show that the system can be substantially completely converted into a carbonate system by introducing carbon dioxide under the control of the second pH value. The sodium carbonate freezing crystallization method adopted by the application overcomes the huge energy consumption caused by the traditional alkali activation process that the alkali waste liquid adopts the traditional heating evaporation process, and the invention also discovers that 180 parts by weight of water can be taken away in the crystallization process of every 106 parts by weight of sodium carbonate by forming sodium carbonate decahydrate in the freezing crystallization process, so that the mother liquor treatment capacity and treatment cost can be greatly reduced while the byproduct recovery capacity is improved, and the comprehensive production cost is further reduced. And under the third pH value, continuously introducing carbon dioxide to ensure that the generated bicarbonate is fully separated out, and the crystallization mother liquor is converted into an aqueous solution rich in carbon dioxide.

10. Preferably, in the processes of recycling the waste liquid produced in the super activated carbon preparation process and recovering the byproducts, the used carbon dioxide is the carbon dioxide produced in the super activated carbon preparation process, and the byproducts of the reaction can be fully utilized, so that the treatment cost is greatly reduced.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In one aspect, the present invention provides a method for preparing super activated carbon, wherein the method comprises:

The inventor of the present invention found in research that the yield of the finally obtained super activated carbon can be effectively increased and the activity thereof can be improved by immersing the oxidizing agent and the hydrated alkaline substance into the interior of the carbonaceous material to be activated under vacuum condition. The present invention does not require any particular vacuum degree under vacuum conditions, as long as the oxidizing agent and the hydrated alkaline activator can be sufficiently impregnated into the carbonaceous material. Preferably, the degree of vacuum of the vacuum condition is-0.001 MPa to-0.099 MPa.

The amounts of the oxidizing agent and the hydrated alkaline activator may also vary within wide ranges according to the present invention, as long as the carbonaceous material is sufficiently corrosion-pore-forming and activating, and for example, the amount of the oxidizing agent may be 0.01 to 4.5 parts by weight based on 100 parts by weight of the carbonaceous material; the amount of the hydrated alkaline activator is 40 to 650 parts by weight.

According to the invention, the addition of the oxidant and the vacuum immersion can selectively corrode the interior of the carbonaceous material without or basically without reducing the volume of the carbonaceous material, thereby effectively improving the yield of the finally prepared super activated carbon and simultaneously carrying out primary activation on the carbonaceous material. The oxidizing agent may be a conventional substance that can act as an oxidizing agent, and may be, for example, but not limited to, ozone, oxygen, hydrogen peroxide, sodium peroxide, ammonium persulfate, potassium permanganate, potassium perchlorate, sodium perchlorate, nitric acid, sodium nitrate, sodium nitrite, potassium nitrate, lithium nitrate, and sodium chromate. These oxidizing agents may be used alone, or 2 or more of them may be used in combination to enhance the oxidizing effect. When the oxidizing agent is a non-gaseous oxidizing agent, the oxidizing agent may be used as an aqueous solution having any concentration as long as the oxidizing agent can be impregnated into the carbonaceous material.

According to the present invention, the hydrated alkaline activator may be a hydrate of an alkaline substance conventionally used in the art for activating carbonaceous materials. However, in the course of research, the inventors of the present invention found that when the hydrated alkaline activator is substantially composed of hydrated sodium hydroxide, and preferably supplemented with a small amount of a supplementary active agent, not only can an alkaline activator, which is mainly potassium hydroxide, be obtained, but also the yield of super activated carbon can be further improved, and in addition, since the solution form of the alkaline activator is not required to be used, the water consumption is effectively reduced, and the cost is reduced. Meanwhile, the pollution is greatly reduced because a large amount of potassium hydroxide with stronger corrosivity is avoided. Wherein the hydrated sodium hydroxide can be selected from NaOH. H₂O，NaOH·2H₂O and NaOH 4H₂At least one of O; the hydrated sodium hydroxide is preferably present in an amount of 50 to 99 weight percent, based on the total weight of the hydrated alkaline activator; the co-activator is preferably selected from KOH, LiOH, Ca (OH)₂At least one of; the content of the co-activator is preferably 0.1 to 35% by weight based on the total weight of the hydrated alkaline activator.

According to the present invention, the oxidizing agent and the hydrated alkaline activator may be contacted with the carbonaceous material in the form of a mixture, or the carbonaceous material may be sequentially contacted with the oxidizing agent and the hydrated alkaline activator in order to further increase the specific surface area of the finally prepared super activated carbon.

Wherein, since the hydrated alkaline activator is in a solid form at ordinary temperature, a form of a non-aqueous solution, and the object of the present invention is also achieved by using just the amount of water carried by the hydrated alkaline activator, when it is used in combination with an oxidizing agent, it is preferable to contact with the carbonaceous material at a temperature at which the hydrated alkaline activator and the oxidizing agent can be converted into a flowable state. The temperature may be, for example, 80 to 300 ℃. The time of the contact is not particularly limited as long as the oxidizing agent and the hydrated alkaline activator can be sufficiently impregnated into the carbonaceous material, and for example, the time of the contact may be 0.5 to 180 min.

In addition, when the carbonaceous material is contacted with the oxidizing agent and the hydrated alkaline activator in this order in order to further increase the specific surface area of the finally prepared super activated carbon, the contact temperature between the carbonaceous material and the oxidizing agent is not particularly limited, and for example, an oxidizing agent in the form of an aqueous solution of an arbitrary concentration may be used at normal temperature, or a molten oxidizing agent may be used at a meltable temperature of the oxidizing agent; the contact time may be 0.5-180 min. And for the contact temperature with the hydrated alkaline activator, it is a temperature at which the hydrated alkaline activator is transformed into a flowable state, for example, 80 to 300 ℃, and the contact time may be 0.5 to 180 min.

In the above manner in which the carbonaceous material is contacted with the oxidizing agent and the hydrated alkaline activator in this order, the method of the present invention further comprises subjecting the carbonaceous material impregnated with the oxidizing agent to a heat treatment B so that the oxidizing agent inside the carbon pores corrodes the carbonaceous material while performing the first activation. The temperature of the heat treatment B is 300-990 ℃, and the time is 5-60 min. The first activated carbonaceous material impregnated with the hydrated alkaline activator is then subjected to a first thermal treatment to further activate the carbonaceous material.

Here, the "first heat treatment" in the "first heat treatment of the first activated carbonaceous material impregnated with the hydrated alkaline activator" is substantially the same as the "first heat treatment" in the "first heat treatment of the carbonaceous material impregnated with the oxidizing agent and the hydrated alkaline activator" in the above step (2). The temperature of the first heat treatment can be 450-1000 ℃, and the time can be 10-600min, preferably, the temperature is 500-850 ℃, and the time is 20-300 min. The "first heat treatment" is preferably performed in an inert gas atmosphere or a reducing gas atmosphere, for example, a gas such as nitrogen or argon.

In addition, it should be noted here that, in the mode of sequentially contacting the carbonaceous material with the oxidizing agent and the hydrated alkaline activator, the contacting with the oxidizing agent and the hydrated alkaline activator is also performed under the vacuum condition, which is the same as the vacuum condition described in the step (1) above, and the details are not repeated here.

According to the present invention, in order to sufficiently activate the carbonaceous material, the method of the present invention further comprises subjecting the carbonaceous material to a heat treatment a for pre-activation before contacting the carbonaceous material with an oxidizing agent. Among them, the carbonaceous material for pre-activation is preferably a carbonaceous material having a water content of 0.5 to 80% by weight, so that a part of the carbonaceous material is pre-activated by the action of water vapor by means of oxidation of water contained therein at a high temperature. The conditions for the heat treatment a preferably include: the temperature is 300-.

According to the present invention, the method of washing the activated carbonaceous material in step (3) may be a washing method conventional in the art, for example, a conventional water washing and acid washing. However, the inventors of the present invention found in the course of their research that the amount of water and acid used in washing can be greatly reduced by washing using the following method, and that the remaining alkaline activator can be recovered and recycled, thereby greatly reducing the production cost. The washing step comprises:

According to the present invention, in step (31), a small amount of water is added to the carbonaceous material activated with the alkaline activator, which greatly reduces the solubility of the produced carbonate due to the presence of the hydrated alkaline activator in the product, and the amount of water used is just enough to allow the remaining hydrated alkaline activator to be just selectively dissolved and leached without substantially dissolving the carbonate component, thereby effectively separating the hydrated alkaline activator from the produced carbonate, and the obtained hydrated alkaline activator preferably can be recycled after being supplemented with the corresponding anhydrous alkaline activator (the amount of water is preferably such that the concentration of the alkaline activator in the obtained activation mother liquor a is 2 to 70% by weight, more preferably 5 to 45% by weight), on the one hand, energy is saved, recycling of water is also achieved, and pollution caused by discharge of the alkaline activator is also reduced, in addition, since the carbonate is not substantially dissolved, the yield of the subsequent by-product can be greatly increased. In addition, the cost is further reduced because the water consumption in the process is less.

The temperature of the first dissolution leaching may be selected from a wide range as long as the above requirements are satisfied, and a person skilled in the art can obtain an appropriate temperature in accordance with the above-described effects. Preferably, the temperature of the first dissolution leaching is 10-350 ℃, more preferably 20-330 ℃.

According to the invention, in step (32), the addition of carbon dioxide enables the unleached alkaline activator to be further converted into the recyclable byproduct carbonate, and at the same time, the solubility of the carbonate is effectively improved due to the great reduction of the alkaline activator, so that the amount of water used for dissolving the carbonate can be greatly reduced, and in this step, the water and carbon dioxide are used in such an amount that carbonate crystals are not precipitated in the system (preferably, the concentration of the carbonate in the carbonate mother liquor B is 1 to 40% by weight, more preferably 2 to 35% by weight). As mentioned above, the amount of water used can be further reduced after the treatment, thereby reducing the cost and the treatment cost of subsequent waste liquid.

The temperature of the second dissolution leaching may be selected from a wide range as long as the above requirements are satisfied, and a person skilled in the art can obtain an appropriate temperature in accordance with the above-described effects. Preferably, the temperature of the second dissolution leaching is 10-150 ℃, more preferably 30-120 ℃.

According to the invention, in the step (3), the multistage hydrolysis and acidification treatment method can be carried out according to the conventional method in the field, but it is noted here that, as the alkaline activating agent and the generated carbonate are mostly separated, the amount of water and acid used in the washing and pickling process is greatly reduced, thus not only reducing the cost, but also reducing the discharge of waste liquid, saving energy and protecting environment.

The acid used for the acid washing may be any one of various acids conventionally used in the art, and may be, for example, but not limited to, one or more of sulfuric acid, hydrochloric acid, nitric acid, formic acid, acetic acid, perchloric acid, fluorosilicic acid, phosphoric acid, and hydrofluoric acid. Preferably, the acid solution has a concentration of 1 to 35% by weight. More preferably 3 to 15 wt%.

According to the present invention, in step (3), in order to further improve the activation effect and the conductivity of the finally prepared activated carbon, the drying step preferably includes: and C, heat treatment: the temperature is 150 ℃ and 500 ℃, and the time is 10-300 min; and (4) heat treatment D: the temperature is 400 ℃ and 1500 ℃, and the time is 10-500 min. Through the two-step heat treatment, in the quick drying process, the pores in the activated carbon can be further opened under the vaporization and impact effects of the residual moisture, and the conductivity of the activated carbon can be properly increased.

According to the invention, in the heat treatment step, due to the corrosion to the carbonaceous material and the high temperature effect, part of carbon can be converted into carbon dioxide to be released, and the preferable water washing step skillfully utilizes the generated carbon dioxide, thereby not only realizing the low emission of waste liquid, but also realizing the utilization of waste gas.

According to the present invention, the carbonaceous material may be a carbonaceous material conventionally used in the art for preparing super activated carbon, and for example, may be shell carbon, petroleum coke or coke. Wherein the shell carbon is preferably selected from one or more of coconut shell carbon, apricot shell carbon, rice bran carbon, Chinese chestnut carbon, peach shell carbon and rapeseed shell carbon; more preferably, the carbonaceous material has a particle size of 20-100 mesh and an ash content of <3 wt%, preferably less than 0.5 wt%, more preferably less than 0.3 wt%.

According to a second aspect of the present invention, the present invention further provides a method for recycling waste liquid produced in a super activated carbon preparation process and producing carbonate as a byproduct, wherein the method comprises:

(1) introducing carbon dioxide into the carbonate mother liquor B obtained in the step (32) at a first alkaline pH value, and performing solid-liquid separation, wherein the first alkaline pH value enables byproducts of hydrated silicon dioxide and carbonate mother liquor C to be obtained without precipitating carbonate crystals;

(3) and (3) introducing carbon dioxide into the crystallization mother liquor D at a third pH value, and carrying out solid-liquid separation to obtain a byproduct bicarbonate crystal and a crystallization mother liquor E.

According to the invention, in the step (1), due to a certain silicon element generally existing in the carbonaceous raw material, the carbonaceous raw material is converted into a water-soluble sodium silicate component in the preparation process of the activated carbon, the sodium silicate can be hydrolyzed into water-insoluble hydrated silica by controlling the pH value of the carbonate mother liquor B and introducing carbon dioxide, so that a silica byproduct (namely white carbon black) is obtained, and meanwhile, the introduction of the carbon dioxide can further convert an alkaline component in the system into carbonate to be beneficial to the next recycling.

According to the invention, in the step (2), the second basic pH value ensures that no bicarbonate is generated or bicarbonate crystals are separated out in the system; so as to obtain a relatively pure carbonate product.

The conditions of the freezing treatment can be selected within a wide range, and the conditions are determined according to the solubility of the carbonate which can be reduced to the maximum extent. Preferably, the temperature of the freezing treatment is-15 ℃ to 25 ℃ and the time is 1-300 min.

Under the control of a second alkaline pH value, the system is basically and completely converted into a carbonate system by introducing carbon dioxide, and on the other hand, the traditional heating evaporation process is converted into the freezing process, so that the solubility of carbonate can be greatly reduced, carbonate byproducts can be fully recovered, and compared with heating evaporation crystallization, the energy consumed by the freezing process is much lower, and the cost is further reduced.

According to the invention, in the step (3), preferably, the pH value and the introduction amount of the carbon dioxide are controlled so that the carbonate in the system is completely converted into the bicarbonate to be precipitated, and meanwhile, the crystallization mother liquor E which is rich in the carbon dioxide and meets the requirements of the step (32) on the amount of water and the carbon dioxide is obtained. Under such preferred conditions, the crystallization mother liquor E may be returned to the step (32) as described above and added as water and carbon dioxide to the solid phase a obtained in the step (31). Under the optimal condition, the crystallization mother liquor E is recycled to the washing step of the super activated carbon, so that zero emission of waste liquid can be realized, and part of water added in the production process is recycled.

Wherein, the pH value of each stage can be selected in a wider range as long as the requirements in the treatment process of each stage are met. Preferably, the first basic pH is greater than a second basic pH, which is greater than a third pH; more preferably, the first alkaline pH is 12.2-13.9; the second alkaline pH value is 10.5-12.1; the third pH value is 3.9-10.4; further preferably, the first alkaline pH is between 12.5 and 13.3; the second alkaline pH value is 10.6-11.3; the third pH value is 4.5-8.2.

According to the invention, the carbon dioxide used in the steps (1) to (3) is the carbon dioxide generated in the preparation of the super activated carbon, so that the byproducts are fully changed into valuable substances, and the cost is reduced.

According to a third aspect of the present invention, the present invention further provides a method for recycling waste liquid produced in a super activated carbon preparation process and producing carbonate as a byproduct, wherein the method comprises:

(5) and (3) introducing carbon dioxide into the crystallization mother liquor D at a third pH value, and carrying out solid-liquid separation to obtain a byproduct bicarbonate crystal and a crystallization mother liquor E.

The processing conditions and requirements of the above steps have been described in detail in the first and second aspects of the present invention, and will not be described in detail herein.

According to the present invention, the carbonaceous material activated with an alkaline activator may be a carbonaceous material activated with an alkaline activator obtained according to a conventional super activated carbon preparation process in the art, for example, a carbonaceous material activated with an alkaline activator obtained in CN01126708.9, CN00107740.6, etc., and may also be a carbonaceous material activated with an alkaline activator obtained according to the method of the present invention.

The present invention will be described in detail below by way of examples. In the following examples of the present invention,

the specific surface area of the super activated carbon was measured by the standard nitrogen adsorption BET method.

Example 1

This example is used to illustrate the preparation method of super activated carbon, the recycling of the produced waste liquid and the by-production of sodium carbonate.

1. Preparation process of super activated carbon

(1) 1kg of apricot hull charcoal was crushed to 40-60 mesh, followed by pre-washing, and the water content of the apricot hull charcoal was made 20 wt%. Then, the heat treatment A process is carried out at 600 ℃ and is kept for 50min to obtain the pre-activated carbon. After cooling, 90 g of 3% sodium peroxide aqueous solution was immersed in a vacuum reactor having a vacuum degree of-0.015 MPa for 5 min.

(2) Heating the pre-activated carbon soaked in sodium peroxide to 640 deg.C again, maintaining for 20min to obtain first activated carbon, cooling the first activated carbon to 120 deg.C, soaking 1.8kg of hydrated sodium hydroxide (NaOH. H) in a vacuum reaction kettle with vacuum degree of-0.06 MPa₂O), and 0.05kg of LiOH is added as an auxiliary activating agent, and the immersion time is controlled to be 30 min;

immersing in NaOH & H in nitrogen atmosphere₂Heating the apricot shell carbon containing O and LiOH to 620 ℃, and keeping the reaction for 65min to perform first heat treatment to obtain the apricot shell carbon subjected to the first heat treatment.

(3) Cooling the first heat-treated apricot shell carbon to 110 ℃, leaching the first activated apricot shell carbon at 110 ℃ by using 1.5kg of water, and centrifugally separating to obtain an activated mother liquor A mainly containing sodium hydroxide and a solid A;

wherein, the obtained activated mother liquor A is analyzed and titrated, and then solid NaOH is supplemented to form hydrated sodium hydroxide (NaOH. H)₂And O) returning to the step (2) for recycling, thereby realizing the recovery of the waste liquid.

(4) Adding 2.9kg of water into the solid A obtained in the step (3), introducing 2L of carbon dioxide, leaching a sodium carbonate byproduct at the temperature of 40 ℃, and performing solid-liquid separation to obtain a carbonate mother liquor B mainly containing sodium carbonate and activated carbon slurry;

wherein, the carbon dioxide is generated in the heat treatment process in each stage, thereby realizing the effective utilization of the waste gas.

(5) Carrying out four-stage washing on the activated carbon slurry, carrying out acidification treatment by using 1.5L of 8% hydrochloric acid solution, and then washing to be neutral to obtain an activated carbon crude product;

wherein, the hydrochloric acid solution in the acid cleaning process can be returned to the acid cleaning process of the next batch of activated carbon for continuous use until the weight percentage of the hydrochloric acid is less than 4.5 percent.

(6) And (4) heating the crude activated carbon product obtained in the step (5) to 320 ℃, keeping the reaction time for 20min, then heating to 850 ℃, and keeping the reaction temperature for crystallization for 70min to obtain the super activated carbon product.

2. Process for recycling produced waste liquid and recycling byproducts

(a) Introducing carbon dioxide into the carbonate mother liquor B obtained in the step (3) until the pH value of the solution is reduced to 13.2, and separating to obtain trace hydrated silicon dioxide (white carbon black) and sodium carbonate mother liquor C;

wherein, at the above pH value, no sodium carbonate and sodium bicarbonate crystal are basically precipitated in the system.

(b) Introducing carbon dioxide into the carbonate mother liquor C until the pH of the solution is reduced to 10.9, freezing the mother liquor C at 5 deg.C, and separating to obtain a large amount of sodium carbonate decahydrate crystals (Na)₂CO₃·10H₂O, sodium carbonate crystals for short hereinafter) and a crystallization mother liquor D;

wherein at the above pH, substantially no sodium hydrogencarbonate crystals precipitated in the system.

(c) Continuously introducing carbon dioxide into the crystallization mother liquor D until the pH value is reduced to 6.9, separating out a small amount of sodium bicarbonate crystals, and separating to obtain sodium bicarbonate solid and crystallization mother liquor E;

wherein the crystallization mother liquor E is rich in carbon dioxide, and can be returned to the step (4) for recycling.

The weight and specific surface area of the obtained super activated carbon were measured, and the dry weights of the obtained byproducts, white carbon black, sodium carbonate and sodium bicarbonate were weighed, and in addition, the amounts of water and acid used in the whole process were recorded. The results are shown in Table 1.

Example 2

1. Preparation process of super activated carbon

(1) 1kg of coconut shell charcoal was crushed to 40-80 mesh, followed by pre-washing, and the moisture content of apricot shell charcoal was made 30% by weight. Then, the heat treatment A process is carried out at 350 ℃, and the temperature is kept for 60min to obtain the pre-activated carbon. After cooling, 50 g of 1% aqueous hydrogen peroxide solution was immersed in a vacuum reactor having a vacuum degree of-0.01 MPa for 10 min.

(2) Heating the pre-activated carbon soaked in hydrogen peroxide to 700 deg.C again, maintaining for 5min to obtain first activated carbon, cooling the first activated carbon to 95 deg.C, soaking 1.5kg of sodium hydroxide hydrate (NaOH.2H2H2H2H2H2O) in a vacuum reaction kettle with vacuum degree of-0.08 MPa₂O), adding 0.3kg of KOH as an auxiliary activating agent, and controlling the immersion time to be 15 min;

immersing in NaOH 2H in nitrogen atmosphere₂Heating the apricot shell charcoal of O and KOH to 680 ℃, and keeping the reaction for 200min to carry out first heat treatment to obtain first heat-treated coconut shell charcoal.

(3) Cooling the first heat-treated coconut shell carbon to 100 ℃, leaching the first activated apricot shell carbon at 105 ℃ by using 1.6kg of water, and performing centrifugal separation to obtain an activation mother liquor A mainly containing sodium hydroxide and a solid A;

wherein, the obtained activated mother liquor A is analyzed and titrated, and then solid NaOH is supplemented to form hydrated sodium hydroxide (NaOH.2HH)₂O) returning to the step (2) for circulationThe waste liquid is recycled.

(4) Adding 3.2kg of water into the solid A obtained in the step (3), introducing 1.5L of carbon dioxide, leaching a sodium carbonate byproduct at the temperature of 45 ℃, and performing solid-liquid separation to obtain a carbonate mother liquor B mainly containing sodium carbonate and activated carbon slurry;

(5) Carrying out four-stage washing on the activated carbon slurry, carrying out acidification treatment by using 1.5L of 10% acetic acid solution, and then cleaning to be neutral to obtain an activated carbon crude product;

wherein, the acetic acid solution in the acid washing process can be returned to the acid washing process of the next batch of activated carbon for continuous use until the weight percentage of the acetic acid is less than 6 percent.

(6) And (4) heating the crude activated carbon product obtained in the step (5) to 200 ℃, keeping the reaction time for 60min, then heating to 500 ℃, and keeping the reaction temperature for crystallization for 150min to obtain the super activated carbon product.

2. Process for recycling produced waste liquid and recycling byproducts

(a) Introducing carbon dioxide into the carbonate mother liquor B obtained in the step (3) until the pH value of the solution is reduced to 12.5, and separating to obtain trace hydrated silicon dioxide (white carbon black) and sodium carbonate mother liquor C;

(b) Introducing carbon dioxide into the carbonate mother liquor C until the pH value of the solution is reduced to 11.3, freezing the mother liquor C at the temperature of 0 ℃, and separating to obtain a large amount of sodium carbonate crystals and a crystallization mother liquor D;

(c) Continuously introducing carbon dioxide into the crystallization mother liquor D until the pH value is reduced to 5.5, separating out a small amount of sodium bicarbonate crystals, and separating to obtain sodium bicarbonate solid and crystallization mother liquor E;

Example 3

1. Preparation process of super activated carbon

(1) 1kg of petroleum coke was sieved with a 50-80 mesh sieve, followed by pre-washing, and the water content of the petroleum coke was brought to 35 wt%. Then, the heat treatment A process is carried out at 850 ℃ and is kept for 10min to obtain the pre-activated carbon. After cooling, 90 g of 1% nitric acid aqueous solution was immersed in a vacuum reactor having a vacuum degree of-0.005 MPa for 35 min.

(2) Heating the pre-activated carbon soaked in dilute nitric acid to 350 deg.C again, maintaining for 60min to obtain first activated carbon, cooling the first activated carbon to 80 deg.C, and soaking in 1.9kg of hydrated sodium hydroxide (NaOH. 4H) in a vacuum reaction kettle with vacuum degree of-0.75 MPa₂O), adding 0.2kg of LiOH as an auxiliary activating agent, and controlling the immersion time to be 25 min;

immersing the glass tube in NaOH 4H in a nitrogen protective atmosphere₂Heating the apricot shell carbon containing O and LiOH to 750 ℃, and keeping the reaction for 20min to perform first heat treatment to obtain petroleum coke subjected to the first heat treatment.

(3) Cooling the petroleum coke subjected to the first heat treatment to 80 ℃, leaching the first activated apricot shell carbon by using 1.6kg of water at the temperature of 80 ℃, and performing centrifugal separation to obtain an activated mother liquor A mainly containing sodium hydroxide and a solid A;

wherein, the obtained activated mother liquor A is analyzed and titrated, and then solid NaOH is supplemented to form hydrated sodium hydroxide (NaOH.4H)₂O) returns to the step (2) for recycling, thereby realizing the aim ofAnd (5) recovering waste liquid.

(4) Adding 3.0kg of water into the solid A obtained in the step (3), introducing 1.5L of carbon dioxide, leaching a sodium carbonate byproduct at the temperature of 55 ℃, and performing solid-liquid separation to obtain a carbonate mother liquor B mainly containing sodium carbonate and activated carbon slurry;

(5) Carrying out four-stage washing on the activated carbon slurry, carrying out acidification treatment by using 1.5L of 5% sulfuric acid solution, and then cleaning to be neutral to obtain an activated carbon crude product;

wherein, the sulfuric acid solution in the pickling process can be returned to the pickling process of the next batch of activated carbon for continuous use until the weight percentage of the sulfuric acid is less than 3 percent.

(6) And (4) heating the crude activated carbon product obtained in the step (5) to 500 ℃, keeping the reaction for 10min, then heating to 1000 ℃, and keeping the reaction temperature for crystallization for 10min to obtain the super activated carbon product.

2. Process for recycling produced waste liquid and recycling byproducts

(a) Introducing carbon dioxide into the carbonate mother liquor B obtained in the step (3) until the pH value of the solution is reduced to 13.0, and separating to obtain trace hydrated silicon dioxide (white carbon black) and sodium carbonate mother liquor C;

(b) Introducing carbon dioxide into the carbonate mother liquor C until the pH value of the solution is reduced to 10.6, freezing the mother liquor C at the temperature of-5 ℃, and separating to obtain a large amount of sodium carbonate crystals and a crystallization mother liquor D;

(c) Continuously introducing carbon dioxide into the crystallization mother liquor D until the pH value is reduced to 7.0, at the moment, precipitating a small amount of sodium bicarbonate crystals, and separating to obtain sodium bicarbonate solid and crystallization mother liquor E;

Example 4

Preparation of super activated carbon and treatment of waste liquid were carried out in the same manner as in example 1 except that the hydrated alkaline activator was 1.52kg of hydrated sodium hydroxide (NaOH. multidot.2HH)₂O) and 0.58kg of hydrated potassium hydroxide (KOH. multidot.2H)₂O). Meanwhile, conventional water washing and acid washing are directly carried out after activation and cooling by using a hydrated alkaline activator. The results are shown in Table 1.

Example 5

The preparation of super activated carbon and the treatment of waste liquid were carried out according to the method of example 1, except that the pre-activated carbon of step (1) was directly immersed using a mixture of an oxidizing agent and a hydrated alkaline activator while controlling the immersion temperature at 110 ℃, and the first heat treatment step was directly carried out after the immersion was completed. The results are shown in Table 1.

Example 6

The preparation of super activated carbon and the treatment of the waste liquid were carried out in the same manner as in example 1 except that the step (6) was combined into one heat treatment, that is, heating at 850 ℃ for 90 min. The results are shown in Table 1.

Example 7

The preparation of super activated carbon and the treatment of waste liquid were carried out according to the method of example 2, except that no auxiliary activator was added in the step (2). The results are shown in Table 1.

Example 8

The preparation of super activated carbon and the treatment of waste liquid were carried out according to the method of example 2, except that the alkaline activation solution used in the activation mother liquor A obtained in step (3) of example 2 was supplemented with 520g of solid NaOH to obtain the alkaline activation solution, which was returned to step (2) for further recycling.

Example 9

The preparation of super activated carbon and the treatment of the waste liquid were carried out in the same manner as in example 2, except that in the recycling of the waste liquid and the recovery of by-products, the pH in step (a) was controlled to 12.0, the pH in step (b) was controlled to 10.0, and the pH in step (c) was controlled to 5.0. The results are shown in Table 1.

Comparative example 1

This comparative example serves to illustrate the reference method

The preparation of super activated carbon and the treatment of the waste liquid were carried out according to the method of example 1, except that the treatment with an oxidizing agent was not carried out, and the corresponding heat treatment B was not carried out. The results are shown in Table 1.

Comparative example 2

This comparative example serves to illustrate the reference method

The preparation of super activated carbon and the treatment of waste liquid were carried out in the same manner as in example 1, except that hydrated sodium hydroxide was not used, but an aqueous solution of sodium hydroxide having a concentration of 35% by weight was directly used. The results are shown in Table 1.

Comparative example 3

This comparative example serves to illustrate the reference method

The preparation of super activated carbon and the treatment of waste liquid were carried out in the same manner as in example 1 except that the impregnation of the oxidizing agent and the hydrated alkaline activator was not carried out under vacuum. The results are shown in Table 1.

TABLE 1 yield, specific surface area and by-product yield of the inventive super-activated carbon

As can be seen from Table 1, the method improves the yield of the super activated carbon while preparing the high-quality super activated carbon, and realizes the recycling of the alkaline activator component in the activated waste liquid and the separation and crystallization processes of the carbonate component to the greatest extent so as to recycle the by-products, and in addition, realizes the recovery of the white carbon black so as to greatly reduce the discharge of the alkaline waste liquid in the production process of the super activated carbon, change the waste production liquid into valuable, and has remarkable social, environmental and economic benefits.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

1. A preparation method of super activated carbon is characterized by comprising the following steps:

(3) cooling, washing and drying the activated carbonaceous material obtained in the step (2) to obtain a super activated carbon product and carbon dioxide gas;

wherein, in the step (3), the washing step comprises:

2. The method of claim 1, wherein the step (1) of contacting the carbonaceous material with the oxidizing agent and the hydrated alkaline activator comprises:

(12) the method includes the steps of contacting a first activated carbonaceous material with a hydrated alkaline activator under vacuum conditions to impregnate the hydrated alkaline activator into the first activated carbonaceous material, and then subjecting the first activated carbonaceous material impregnated with the hydrated alkaline activator to a first heat treatment under an inert gas atmosphere or a reducing gas atmosphere.

3. The preparation method according to claim 2, wherein the oxidizing agent is used in an amount of 0.01 to 4.5 parts by weight based on 100 parts by weight of the carbonaceous material in step (11).

4. The production method according to claim 2, wherein in step (11), the conditions of the heat treatment B include: the temperature is 300-990 ℃, and the time is 5-60 min.

5. The production method according to claim 2, wherein in the step (11), the oxidizing agent is at least 1 selected from the group consisting of ozone, oxygen, hydrogen peroxide, sodium peroxide, ammonium persulfate, potassium permanganate, potassium perchlorate, sodium perchlorate, nitric acid, sodium nitrate, sodium nitrite, potassium nitrate, lithium nitrate, and sodium chromate.

6. The production method according to claim 2, wherein in the step (11), the oxidizing agent is at least 2 selected from the group consisting of ozone, oxygen, hydrogen peroxide, sodium peroxide, ammonium persulfate, potassium permanganate, potassium perchlorate, sodium perchlorate, nitric acid, sodium nitrate, sodium nitrite, potassium nitrate, lithium nitrate, and sodium chromate.

7. The preparation method according to claim 2, wherein the hydrated alkaline activator is used in an amount of 40 to 650 parts by weight based on 100 parts by weight of the carbonaceous material in step (12).

8. The method of claim 2, wherein the conditions for contacting the first activated carbonaceous material with the hydrated alkaline activator in step (12) comprise: the contact temperature is 80-300 deg.C, and the contact time is 0.5-180 min.

9. The production method according to claim 2, wherein in step (12), the conditions of the first heat treatment include: the temperature is 450 ℃ and 1000 ℃, and the time is 10-600 min.

10. The method according to claim 2, wherein in the step (12), the hydrated alkaline activator contains hydrated sodium hydroxide selected from NaOH. H₂O，NaOH·2H₂O and NaOH 4H₂At least one of O; the hydrated sodium hydroxide is present in an amount of 50 to 99 weight percent based on the total weight of the hydrated alkaline activator.

11. The method according to claim 10, wherein in the step (12), the hydrated alkaline activator further comprises a co-activator selected from KOH, LiOH, Ca (OH)₂At least one of; the content of the auxiliary activator is 0.1 to 35% by weight based on the total weight of the hydrated alkaline activator.

12. The production method according to claim 1, wherein the vacuum condition has a degree of vacuum of-0.001 MPa to-0.099 MPa.

13. The method of claim 2, further comprising: pre-activating a carbonaceous material prior to contacting the carbonaceous material with an oxidant, while obtaining carbon dioxide gas, the pre-activation comprising heat treating a carbonaceous material having a water content of 0.5-80 wt.% a; the conditions of the heat treatment A comprise: the temperature is 300 ℃ and 900 ℃, and the time is 5-100 min.

14. The method of claim 1, wherein the first dissolution leaching temperature is 10-350 ℃ in step (31).

15. The preparation method of claim 1, wherein in the step (31), the step further comprises supplementing an alkaline activator to the activation mother liquor A to obtain the hydrated alkaline activator, and returning the hydrated alkaline activator to the step (2) for recycling.

16. The production method according to claim 1, wherein in the step (32), the water and the carbon dioxide are used in such amounts that carbonate crystals are not precipitated in the system.

17. The method of claim 1, wherein the temperature of the second dissolution leaching in step (32) is 10-150 ℃.

18. The production method according to claim 1, wherein in the step (32), the carbon dioxide used in the step is carbon dioxide produced by the production method according to claim 1, 2 or 13.

19. The production method according to claim 1, wherein in the step (33), the acid used for the acidification treatment is one or more selected from sulfuric acid, hydrochloric acid, nitric acid, formic acid, acetic acid, perchloric acid, fluorosilicic acid, phosphoric acid, and hydrofluoric acid.

20. The production method according to any one of claims 1 to 17 and 19, wherein, in the step (3), the drying includes:

21. The method of any one of claims 1-17 and 19, wherein the carbonaceous material is selected from the group consisting of husk carbon, petroleum coke, and coke.

22. The method according to claim 21, wherein the shell carbon is selected from one or more of coconut shell carbon, apricot shell carbon, rice bran carbon, chestnut carbon, peach shell carbon and rapeseed shell carbon.

23. The method of claim 21 wherein the carbonaceous material has a particle size of 20 to 100 mesh and an ash content of <3 wt.%.

24. A method for recycling waste liquid produced by a super activated carbon preparation process and producing carbonate as a byproduct is characterized by comprising the following steps:

(1) introducing carbon dioxide into the carbonate mother liquor B obtained in step (32) of claim 1 at a first alkaline pH value which allows by-products hydrated silica and carbonate mother liquor C to be obtained without precipitation of carbonate crystals, and carrying out solid-liquid separation;

wherein the crystallization mother liquor E is returned to the step (32) of claim 1 as water and carbon dioxide to be added to the solid phase A obtained in the step (31); wherein the third pH value enables the water and carbon dioxide content of the obtained crystallization mother liquor E to meet the requirements of the water and carbon dioxide dosage in the step (32).

25. The process of claim 24, wherein the second basic pH is such that no bicarbonate crystals precipitate in the system.

26. The process of claim 24, wherein the freezing process is carried out at a temperature of-15 ℃ to 25 ℃ for a period of 1-300 min.

27. The process according to claim 24, wherein the carbon dioxide used in steps (1) to (3) is carbon dioxide produced by the production process according to claim 1, 2 or 13.

28. The treatment process of claim 24, wherein the first basic pH is greater than a second basic pH, the second basic pH being greater than a third pH.

29. The process of claim 28, wherein the first basic pH is 12.2-13.9; the second alkaline pH value is 10.5-12.1; the third pH value is 3.9-10.4.

30. The process of claim 28, wherein the first basic pH is between 12.5 and 13.3; the second alkaline pH value is 10.6-11.3; the third pH value is 4.5-8.2.

31. A method for recycling waste liquid produced by a super activated carbon preparation process and producing carbonate as a byproduct is characterized by comprising the following steps:

wherein, in the step (1), the step further comprises supplementing an alkaline activating agent to the activation mother liquor A and returning the activation mother liquor A to the preparation method of the super activated carbon according to any one of claims 1 to 23 for recycling.

32. The process of claim 31, wherein the temperature of the first dissolution leaching in step (1) is 10-350 ℃.

33. The process according to claim 31, wherein in the step (2), the water and the carbon dioxide are used in such amounts that no carbonate crystals are precipitated in the system.

34. The process defined in claim 31 wherein in step (2) the temperature of the second dissolution leach is from 10 to 150 ℃.

35. The process of claim 31, wherein in step (4), the second basic pH is such that no bicarbonate crystals precipitate from the system.

36. The process of claim 31, wherein in step (4), the temperature of the freezing process is from-15 ℃ to 25 ℃ for 1 to 300 min.

37. The process according to claim 31, wherein, in step (5), the crystallization mother liquor E is returned to step (2) to be added as water and carbon dioxide to the solid phase A; and (3) the third pH value enables the water and carbon dioxide content of the obtained crystallization mother liquor E to meet the requirements of the water and carbon dioxide dosage in the step (2).

38. The process according to claim 31, wherein the carbon dioxide used in the steps (2) to (5) is carbon dioxide produced by the method for producing super activated carbon according to any one of claims 1 to 23.

39. The treatment process of claim 31, wherein the first basic pH is greater than a second basic pH, the second basic pH being greater than a third pH.

40. The process of claim 39, wherein the first basic pH is from 12.2 to 13.9; the second alkaline pH value is 10.5-12.1; the third pH value is 3.9-10.4.

41. The process of claim 39, wherein the first basic pH is between 12.5 and 13.3; the second alkaline pH value is 10.6-11.3; the third pH value is 4.5-8.2.