CN113120899A

CN113120899A - Activated carbon and preparation method and application thereof

Info

Publication number: CN113120899A
Application number: CN202110435136.5A
Authority: CN
Inventors: 沈伯雄; 张瑜
Original assignee: Hebei University of Technology
Current assignee: Hebei University of Technology
Priority date: 2021-04-22
Filing date: 2021-04-22
Publication date: 2021-07-16

Abstract

The invention relates to the technical field of preparation of activated carbon from solid waste garbage, in particular to activated carbon and a preparation method and application thereof. The invention provides a preparation method of activated carbon, which comprises the following steps: mixing the rotten biomass, the waste textile and water, and fermenting to obtain a blending fermentation product; carrying out pyrolysis carbonization on the blended fermentation product to obtain the activated carbon; the fermentation temperature is 0-60 ℃, and the fermentation time is 0.1-150 h. The activated carbon prepared by the preparation method has a large specific surface area and high activity.

Description

Activated carbon and preparation method and application thereof

Technical Field

The invention relates to the technical field of preparation of activated carbon from solid waste garbage, in particular to activated carbon and a preparation method and application thereof.

Background

The production of textiles consumes a large amount of natural fibers such as cotton, wool, silk and hemp, as well as blended and synthetic fibers which are extracted from non-renewable resources such as petroleum. Most of the textiles become waste textiles after a few years, and the recovery ratio of the waste textiles is very low, so that the waste textiles can not be recycled. Therefore, how to treat these waste textiles is the key to realizing sustainable development at present.

The traditional method for treating the waste textiles mainly comprises incineration treatment and landfill treatment. In the actual landfill treatment, the waste textile fibers not only contain pure cotton fabrics, but also have huge occupation ratio of blended fibers and synthetic fibers (such as terylene, polypropylene fibers, acrylic fibers and the like), and the process of the blended fibers and the synthetic fibers is very slow, so if the landfill treatment is carried out, not only are material resources wasted, but also the soil is hardened, the activity of the soil is damaged, and the waste of land resources is caused. The incineration treatment is used as the most direct energy recovery mode to convert high-calorific-value chemical fibers in waste textiles into heat for thermal power generation, the method is simple to operate and low in cost, a large number of waste blended fibers which are not easy to degrade can be treated, but a large amount of smoke containing toxic and harmful substances, including a large amount of persistent organic pollutants such as PM10, PM2.5 and dioxin, can be generated in the incineration process, and great damage is caused to the environment and human health.

The biological composite carbon material prepared by using the waste textiles can solve the problem of environmental pollution caused by the traditional treatment method, can solve the problems of resource shortage and waste to a certain extent, achieves real environmental protection and low carbon, and has certain economic and social benefits. The carbon material obtained by pyrolysis and carbonization has excellent conductivity, chemical stability and porosity, so that the carbon material has wide application in the aspects of air purification, sewage treatment, sensing, energy storage and conversion and biomedicine. Therefore, the recycling of textile wastes and wastes generated in the textile production process protects the limited resources in the world and the natural environment, which is the inevitable trend of the economic sustainable development of China.

At present, a lot of difficulties exist in preparing carbon by using waste textiles, and the carbon synthesized by direct pyrolysis often has poor performance (such as small specific surface area and low activity).

Disclosure of Invention

The invention aims to provide a preparation method of activated carbon, and the activated carbon prepared by the preparation method has a large specific surface area and high activity.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of activated carbon, which comprises the following steps:

mixing the rotten biomass, the waste textile and water, and fermenting to obtain a blending fermentation product;

carrying out pyrolysis carbonization on the blended fermentation product to obtain the activated carbon;

the fermentation temperature is 0-60 ℃, and the fermentation time is 0.1-150 h.

Preferably, the spoiled biomass comprises one or more of spoiled vegetables, spoiled fruits and spoiled super-enriched plants.

Preferably, the mass ratio of the rotten biomass to the waste textiles is (0.01-100): 1.

preferably, the volume ratio of the total mass of the rotten biomass and the waste textiles to the water is 1 g: (0.1-5) mL.

Preferably, the drying of the blended fermentation product is further included before the pyrolysis carbonization;

the drying temperature is 100-110 ℃, and the drying time is 20-25 h.

Preferably, the pyrolytic carbonization is carried out in a protective atmosphere;

the gas of the protective atmosphere is one or more of carbon dioxide, nitrogen and inert gas.

Preferably, the temperature of the pyrolysis carbonization is 300-1600 ℃, the heating rate is 0.1-1000 ℃/min, and the time is 0.1-10 h.

Preferably, after the pyrolysis carbonization is finished, ball milling is further included;

the rotation speed of ball milling is 100-1000 r/min, the time is 0.01-100 h, and the ball-material ratio is (0.01-100): 1.

the invention also provides the activated carbon prepared by the preparation method in the technical scheme.

The invention also provides application of the activated carbon in the technical scheme in the field of adsorption of heavy metals and organic pollutants in wastewater.

The invention provides a preparation method of activated carbon, which comprises the following steps: mixing the rotten biomass, the waste textile and water, and fermenting to obtain a blending fermentation product; carrying out pyrolysis carbonization on the blended fermentation product to obtain the activated carbon; the fermentation temperature is 0-60 ℃, and the fermentation time is 0.1-150 h. Because the biomass is decomposed by microorganisms such as various molds and bacteria in the process of rotting, a large amount of metabolites such as organic acid aldehyde and the like are generated in the decomposition process, and the biomass is strongly acidic. Due to the activation effect of the organic acid, the pore structure of the activated carbon prepared by pyrolysis is reasonably distributed, and hetero atoms are doped to improve the functional groups of active sites of the material, so that abundant active functional groups are obtained, and the adsorption performance of the material is improved. And the fruit residues after complete decomposition become slightly acidic or neutral, so the fermentation process is not suitable to be overlong, and the fruit residues are taken out when the content of acidic substances is proper, dried and pyrolyzed. Fermentation time is therefore an important parameter affecting the destruction of biomass-activated textile fibres. Meanwhile, the fermentation temperature also influences the fermentation speed of the zymophyte, and has great influence on the selection of the optimal fermentation time. The method comprises the steps of mixing the rotten biomass and the waste textiles, and then fermenting, wherein in the fermentation process, substances such as starch, protein, plant fibers, pectin and metabolites generated in the rotten biomass can be further decomposed and converted into amino acid, glucose, humus, mineral elements and the like, and the substances are used as a carbon source and a doping element source in the subsequent pyrolysis carbonization process, so that in the process of carrying out pyrolysis carbonization together with the waste textiles, the active carbon is obtained, the doping of the active carbon is realized, active sites on the active carbon material are further increased, the activity of the active carbon material is improved, and the adsorption performance of the material is improved. The zymophyte uses cellulose, fructose and the like as raw materials, and produces metabolites such as organic acid aldehyde and the like through anaerobic respiration and serves as an activator to activate the waste textiles. The general name of the bacteria and fungi existing in the rotten fruit and vegetable pulp and the rotten biomass of the zymophyte) are simultaneously used as a carbon source, a nitrogen source and the like, and the high-quality active carbon adsorption material which is doped with elements and has reasonable pore size distribution is generated together with the waste textile fibers.

Drawings

FIG. 1 is a graph of pH of blended fermentates as a function of fermentation time during a fermentation process as described in example 1;

FIG. 2 is an XPS plot of N1s for the activated carbon described in example 1;

FIG. 3 is a nitrogen isothermal Torr adsorption curve of the activated carbon described in example 1;

FIG. 4 is a plot of the pore size distribution of the activated carbon described in example 1.

Detailed Description

the fermentation temperature is 0-60 ℃, and the fermentation time is 0.1-50 h.

In the present invention, all the starting materials for the preparation are commercially available products known to those skilled in the art unless otherwise specified.

The method comprises the steps of mixing rotten biomass, waste textiles and water, and fermenting to obtain a blending fermentation product; the fermentation temperature is 0-60 ℃, and the fermentation time is 0.1-50 h.

In the present invention, the spoiled biomass preferably comprises one or more of spoiled vegetables, spoiled fruits and spoiled super-enriched plants; the type of the rotten vegetables is not limited in any way in the present invention, and may be any type known to those skilled in the art, and in the embodiment of the present invention, the rotten vegetables are specifically rotten tomatoes; in the invention, the rotten fruit is more preferably one or more of rotten apples, rotten pears, rotten lemons and rotten grapes; the type of the super-enriched plants with rotten rot is not particularly limited in the present invention, and the types well known to those skilled in the art can be used.

Before mixing, the invention preferably breaks the spoiled biomass; the process of crushing is not limited in any way, and the crushed rotten biomass is made into slurry by a process well known to those skilled in the art.

In the invention, the waste textile is preferably one or more of waste denim, waste cotton cloth, waste linen and waste blended cloth; the waste blended fabric is not limited in any way, and the waste blended fabric can be prepared by the method well known to those skilled in the art.

Before mixing, the waste textiles are preferably crushed; the crushing process is not limited at all, and the area of the crushed waste textiles is 0.1-1 cm by adopting the process known by the technical personnel in the field²The block shape is just needed.

In the present invention, the mixing is preferably performed by mixing the spoiled biomass and the waste textile and then mixing the mixture with water. In the invention, the mixing mode of the rotten biomass and the waste textiles is preferably stirring, grinding or ball milling; the stirring, grinding or ball milling process is not particularly limited in the present invention, and may be performed by a process known to those skilled in the art. The mixing process with water is not particularly limited, and may be performed by a process known to those skilled in the art.

In the invention, the mass ratio of the rotten biomass to the waste textiles is preferably (0.01-100): 1, more preferably (0.1 to 60): 1, most preferably (1-30): 1.

in the invention, the volume ratio of the total mass of the spoiled biomass and the waste textiles to the water is preferably 1 g: (0.1-5) mL, more preferably 1 g: (0.1-3) mL.

In the invention, the fermentation temperature is 0-60 ℃, preferably 16-45 ℃; the time is 0.1 to 150 hours, preferably 1 to 100 hours, and more preferably 10 to 50 hours.

In the invention, metabolites such as organic acid, aldehyde and the like obtained by fermentation can be used as an activator to activate the waste textiles, the rotten biomass and fermentation bacteria (a general term for bacteria and fungi existing in the rotten biomass) in the waste textiles and the rotten biomass can be simultaneously used as a carbon source and a heteroatom doping source to generate heteroatom-doped activated carbon together with the waste textiles.

After the blending fermentation product is obtained, the blending fermentation product is pyrolyzed and carbonized to obtain the activated carbon.

Before the pyrolysis carbonization, the invention also preferably comprises drying the blended fermentation product; the drying temperature is preferably 100-110 ℃, and more preferably 105 ℃; the time is preferably 20-25 h, and more preferably 24 h.

In the present invention, the pyrolytic carbonization is preferably performed in a protective atmosphere; the gas of the protective atmosphere is preferably one or more of carbon dioxide, nitrogen and inert gas; the inert gas is preferably argon or helium.

In the invention, the temperature of the pyrolysis carbonization is preferably 300-1600 ℃, more preferably 400-1200 ℃, and most preferably 500-1000 ℃; the heating rate is preferably 0.1-1000 ℃/min, more preferably 1-100 ℃/min, and most preferably 5-50 ℃/min; the time is preferably 0.1 to 10 hours, and more preferably 1 to 5 hours.

In the present invention, the pyrolysis carbonization is preferably performed in a tube furnace.

In the invention, the pyrolysis carbonization temperature is too low, the pyrolysis carbonization retention time is too short, the pyrolysis carbonization is insufficient, the situation that the active carbon is not formed with pores or has small pore volume is caused, and the pyrolysis temperature is too high, the pyrolysis retention time is too long, the pore structure of the prepared active carbon is subjected to structural collapse due to excessive pyrolysis, so that the adsorption performance of the active carbon is weakened. Therefore, the temperature and time for pyrolysis carbonization can be controlled within the above ranges, so that the prepared activated carbon has stronger adsorption performance.

After the pyrolysis carbonization is completed, the present invention also preferably includes ball milling. In the invention, the rotation speed of the ball milling is preferably 100-1000 r/min, more preferably 200-800 r/min, and most preferably 300-600 r/min; the time is preferably 0.01-100 h, more preferably 1-80 h, and most preferably 10-50 h; the ball-to-feed ratio is preferably (0.01-1000): 1, more preferably (1-500): 1, and most preferably (10-200): 1. In the invention, the grinding balls used in the ball milling treatment are preferably agate balls.

In the invention, the ball milling treatment has the effects of increasing the specific surface area of the activated carbon and increasing the content of functional groups on the surface of the carbon material, thereby improving the adsorption efficiency.

The invention also provides application of the activated carbon in the technical scheme in the field of adsorption of heavy metals and organic pollutants in wastewater. The method of the present invention is not particularly limited, and the method may be performed by a method known to those skilled in the art.

The activated carbon provided by the present invention, its preparation method and application are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.

Example 1

Crushing 100g of rotten apples into pulp and 10g of waste cotton cloth into pieces with an area of 0.1cm²Stirring and mixing the blocks in a crushing stirrer to obtain a blend, mixing the blend with 15mL of water, and fermenting in a clean fermentation tank at the temperature of 25 ℃ for 12 hours to obtain a blended fermentation product;

drying the blended fermentation product in a tube furnace (the temperature is 105 ℃ and the time is 24 hours); sequentially carrying out pyrolysis carbonization and ball milling in a nitrogen atmosphere, wherein the pyrolysis carbonization temperature is 600 ℃, the heating rate is 5 ℃/min, and the time is 2 h; the ball milling time is 10h, and the mass ratio of the agate balls to the materials is 80: 1, rotating at a speed of 400r/min to obtain the active carbon (marked as DCP);

and (2) placing 5mg of the activated carbon in 50mL of solution with the cadmium ion concentration of 50mg/L and the Congo red dye of 40mg/mL, and after absorbing for 48 hours at the temperature of 25 ℃, the cadmium ion concentration is 2.5mg/L and the Congo red dye is 1.9 mg/mL. Therefore, the activated carbon has good adsorption effect on cadmium ions and dyes in water, and the removal efficiency can reach more than 95%;

FIG. 1 is a graph showing the pH of the mixed fermentation product during the fermentation process as a function of the fermentation time, wherein the abscissa indicates the fermentation time (h) and the ordinate indicates the pH; as can be seen from FIG. 1, when the fermentation time reaches 12h, the pH value reaches the lowest, the acidity is the strongest at the moment, and the activation effect is the best;

FIG. 2 is an XPS plot of N1s of the activated carbon, wherein the abscissa Binding Energy (ev) indicates Binding Energy, and the ordinate Intensity (a.u) indicates strength, and it can be seen from FIG. 2 that N element is successfully doped on the activated carbon, so that the functional groups on the surface of the activated carbon are increased to increase the polarity of the surface of the activated carbon and improve the adsorption efficiency;

FIG. 3 is a nitrogen isothermal desorption curve of the activated carbon; wherein the abscissa P/P0 indicates the relative pressure and the ordinate quality adsorption indicates the adsorption amount, and it can be seen from FIG. 3 that nitrogen adsorption conforms to type IV of IUPAC classification. The adsorption process is S-shaped. In the desorption process, due to the existence of a large number of mesopores, the capillary condensation of the adsorbate in a certain relative pressure range is in a saturated state, and an H-shaped hysteresis curve appears;

the surface area and pore characteristics of the activated carbon were measured using a nitrogen adsorption and desorption apparatus (asap 2020, micromeritics, usa), and the results are shown in table 1 and fig. 4, fig. 4 being a pore size distribution curve of the activated carbon; wherein the abscissa Pore width (nm) refers to the Pore width, the ordinate Incremental Pore volume refers to the Incremental Pore volume,

table 1 BET analysis of activated carbon as described in example 1

Note: wherein "SBET" represents specific surface area; "VT" represents total pore volume; "V μ" represents the micropore volume; "VM" represents the mesopore volume; "DP" represents the average pore diameter;

as can be seen from fig. 4 and table 1, the pore distribution of the activated carbon also has micropores and mesopores, and the micropore structure accounts for 44%.

Congo red has a molecular weight of 696.68 and belongs to an organic macromolecule. When the pore diameter of the porous material is less than 1.7 times the size of the adsorbate molecule, the repulsion between adsorbate molecules increases significantly, which requires higher adsorption energy. Thus, congo red molecules cannot enter the obtained micropores. Cadmium ions just fill up the vacancy of the micropores, and the micro-mesoporous space is fully utilized.

Example 2

Crushing 100g of rotten lemon into pulp and 10g of waste cotton cloth into pieces with area of 0.1cm²Mixing the blocks in a ball milling mode to obtain a blend, mixing the blend with 13mL of water, and fermenting in a clean fermentation tank at the temperature of 30 ℃ for 10 hours to obtain a blended fermentation product;

drying the blended fermentation product in a tube furnace (the temperature is 105 ℃ and the time is 24 hours); sequentially carrying out pyrolysis carbonization and ball milling in a nitrogen atmosphere, wherein the pyrolysis carbonization temperature is 700 ℃, the heating rate is 10 ℃/min, and the time is 2 h; the ball milling time is 12h, the mass ratio of the agate balls to the materials is 100: 1, rotating at a speed of 500r/min to obtain the activated carbon;

and (2) placing 5mg of the activated carbon in 50mL of solution with the cadmium ion concentration of 60mg/L and the Congo red dye of 50mg/mL, and adsorbing for 48 hours at the temperature of 25 ℃, wherein the cadmium ion concentration is 2.3mg/L and the Congo red dye is 2.0 mg/mL. Therefore, the activated carbon has good adsorption effect on cadmium ions and dyes in water, and the removal efficiency can reach more than 96%;

the pore structure of the activated carbon was tested and the test results were similar to example 1.

Example 3

Crushing 100g of rotten grapes into slurry and 10g of waste cotton cloth into pieces with an area of 0.1cm²Mixing the blocks in a crushing and stirring manner to obtain a blend, mixing the blend with 11mL of water, and fermenting in a clean fermentation tank at the temperature of 45 ℃ for 11 hours to obtain a blended fermentation product;

drying the blended fermentation product in a tube furnace (the temperature is 105 ℃ and the time is 24 hours); sequentially carrying out pyrolysis carbonization and ball milling in a nitrogen atmosphere, wherein the pyrolysis carbonization temperature is 600 ℃, the heating rate is 5 ℃/min, and the time is 3 h; the ball milling time is 14h, and the mass ratio of the agate balls to the materials is 120: 1, rotating at the speed of 600r/min to obtain the activated carbon;

and (2) placing 5mg of the activated carbon in 50mL of solution with the cadmium ion concentration of 60mg/L and the Congo red dye of 50mg/mL, and adsorbing for 48 hours at the temperature of 25 ℃, wherein the cadmium ion concentration is 3.0mg/L and the Congo red dye is 2.5 mg/mL. Therefore, the activated carbon has a good adsorption effect on cadmium ions and dyes in water, and the removal efficiency can reach 95%;

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

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

2. The method of claim 1, wherein the spoiled biomass comprises one or more of spoiled vegetables, spoiled fruits and spoiled super-enriched plants.

3. The preparation method according to claim 1 or 2, wherein the mass ratio of the spoiled biomass to the waste textiles is (0.01-100): 1.

4. the method of claim 1, wherein the ratio of the total mass of the spoiled biomass to the waste textile to the volume of water is from 1 g: (0.1-5) mL.

5. The method of claim 1, further comprising drying the blended fermentation product prior to the pyrolytically carbonizing;

the drying temperature is 100-110 ℃, and the drying time is 20-25 h.

6. The production method according to claim 1 or 5, wherein the pyrolytic carbonization is performed in a protective atmosphere;

7. The preparation method according to claim 6, wherein the pyrolysis carbonization temperature is 300 to 1600 ℃, the temperature rise rate is 0.1 to 1000 ℃/min, and the time is 0.1 to 10 hours.

8. The method of claim 1 or 7, wherein the pyrolysis carbonization is completed, and further comprising ball milling;

9. the activated carbon prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the activated carbon of claim 9 in the field of adsorption of heavy metals and organic pollutants in wastewater.