WO2023024365A1 - Method for preparing activated carbon by using areca nut and sludge as materials - Google Patents

Abstract

A method for preparing activated carbon by using areca nut and sludge as materials. The method comprises the following steps: S1. preparation of raw materials, involving mixing and drying areca nut and a sludge, crushing and screening same, so as to obtain mixed granules of the areca nut and the sludge; S2. high temperature carbonization, involving placing the mixed raw materials into a tube furnace, performing a primary treatment of carbonization in a nitrogen atmosphere; S3. soaking in an activator, involving mixing the mixed granules of the areca nut and the sludge after carbonization with an aqueous activator solution, the aqueous activator solution being prepared from phosphoric acid, zinc chloride and water, stirring well and soaking, so as to obtain a mixed product; S4. high temperature activation, involving placing the mixed product into a tube furnace, activating same in a nitrogen atmosphere, cooling same to obtain a crude product; and S5. obtaining a final product, involving subjecting the crude product to acid washing, washing with water and drying, so as to obtain a target activated carbon product. The areca nut-sludge activated carbon prepared by the method has the advantages of a variety of pore structures, a large specific surface area, a high iodine adsorption capacity and a high yield. Moreover, the method is low in terms of energy consumption and simple to operate.

Description

A kind of method that utilizes betel nut and sludge as material to prepare activated carbon technical field

The application relates to the field of activated carbon, in particular to a method for preparing activated carbon using areca nuts and sludge as materials.

Background technique

With the rapid development of urban sewage plants, a large amount of sludge is produced. Sewage sludge is a by-product of sewage treatment. About 50% of the weight of sewage sludge is organic matter, most of which are hemicellulose, cellulose, lignin, lipids and proteins, which can be utilized as resources.

Lignocellulosic materials (such as coconut shells, corn stalks, sawdust, plant stalks, and betel nuts, etc.) as activated carbon materials containing a large amount of organic matter and rich in carbon can be prepared simply by pyrolysis process with large specific surface area, stable physical and chemical properties and Activated carbon with excellent adsorption capacity. In addition, these cellulose-rich materials have the advantages of abundant sources, renewable, low cost of production raw materials, simple preparation methods, etc., and have excellent properties compared with traditional materials (such as coal, petroleum, etc.). However, due to the low carbon content of sludge, its wide application is limited. Therefore, these lignocellulosic materials are added to sludge precursors to enhance the performance of activated carbon, especially lignocellulosic materials (e.g. coconut shells, etc.) readily available from pharmaceutical sources.

At present, the main methods of synthesizing activated carbon are chemical activation, physical activation and the combination of the two. In physical activation, activated gases such as carbon dioxide, air, or water vapor are used during pyrolysis to etch the surface of carbon substrates at high temperature, i.e., causing significant changes in the morphology and pore structure of the carbon substrates. There are oxidative dehydrogenation reactions during pyrolysis, leading to structural disorder and the formation of pores. The activated carbon produced by physical activation is mainly microporous activated carbon, but the operating conditions of physical activation (high temperature and high energy consumption) limit its industrial application, and the surface will be severely burned, which reduces the carbon production rate. The chemical activation process is well established and involves the use of alkali metals, acids and salts such as KOH, NaOH, H ₃ PO ₄ , H ₂ SO ₄ , ZnCl ₂ and CaCl ₂ . Chemical activation causes swelling, dehydration, and aromatic condensation of activated carbon and carbon to form a large and uniform mesoporous structure and high specific surface area. Compared with physical activation methods, chemical methods have lower energy and time consumption and higher efficiency. Lin et al. observed that co-pyrolysis of oil palm solid waste and paper sludge at low temperature enhanced thermochemical reactivity. They are attributed to hydrogenation and thermocatalysis. As a porous carbon-containing adsorption material, these mixed activated carbons are low in preparation cost and are beneficial to the treatment of environmental pollution. They can not only meet the reduction, harmlessness, resource utilization and stabilization of a large amount of urban sludge, but also "turn waste into treasure". And treating waste with waste, which brings environmental benefits and promotes economic benefits at the same time, is a very meaningful research direction. However, the performance of synthetic activated carbon prepared from existing sludge is not good enough, the adsorption capacity is not strong enough, and the yield is low. Therefore, it is necessary to mix betel nut and sludge to prepare activated carbon, which can not only improve the adsorption performance and yield, but also reduce environmental pollution by waste utilization.

Contents of the invention

In view of this, the present application proposes a method for preparing activated carbon using areca nuts and sludge as materials to overcome the deficiencies in the prior art.

The technical scheme of the present application is realized like this:

A kind of method that utilizes betel nut and sludge to prepare gac for material, comprises the following steps:

S1. Raw material preparation: mix and dry areca nuts and sludge, crush and sieve to obtain mixed particles of betel nuts and sludge;

S2, high-temperature carbonization: place the betel nut and sludge mixed particles obtained in step S1 in a tube furnace, and carry out carbonization initial treatment in a nitrogen atmosphere. The carbonization temperature is 600-700 ° C, and the carbonization time is 30-90 minutes. Mixed granules of betel nut and sludge;

S3, activator soaking: get the betel nut after the carbonization of step S2 and the mixed sludge of sludge and mix with activator aqueous solution, described activator aqueous solution is made by phosphoric acid, zinc chloride and water, the content of zinc chloride in described activator aqueous solution The concentration is 2.0-3.5mol/L, and the concentration of phosphoric acid is 2.5-3.5mol/L; the mass volume ratio of the betel nut and sludge mixed particles to the activator aqueous solution is 1:2.0-3.0, and soaked for 12 -48h, obtain mixed product;

S4. High-temperature activation: put the mixed product activated in step S3 into a tube furnace, and activate it in a nitrogen atmosphere, wherein the activation temperature is 700-800°C, the activation time is 0.5-2h, and the crude product is obtained after cooling;

S5. Finished product: the crude product in step S4 is pickled, washed with water, and dried to obtain the target activated carbon product.

Further, in step S1, the betel nut and the sludge are mixed and dried until the water content is 10%-20%.

Further, in step S1, the mesh size of the sieve is 100-200 mesh.

Further, in step S2, the temperature is raised to 600-700° C. at a rate of 10-20° C./min for carbonization.

Further, in step S3, the soaking temperature is 20-33°C.

Further, in step S4, the temperature is raised to 700-800° C. at a heating rate of 10-20° C./min for activation.

Further, the specific operation of step S5 is: repeatedly washing the crude product with hydrochloric acid and distilled water to remove inorganic substances, and then drying at 105° C. to constant weight.

Further, in step S3, the concentration of zinc chloride in the aqueous solution of the activator is 3.0mol/L, and the concentration of phosphoric acid is 3.0mol/L; the mass volume ratio of the mixed particles of betel nut and sludge to the aqueous solution of the activator is kg/ L is 1:2.0.

Further, in step S3, the soaking time is 20h.

Further, in step S4, the activation temperature is 800° C., and the activation time is 1 h.

Compared with prior art, the beneficial effect of the present application is:

(1) This application adopts the blending of betel nut and sludge, conducts preliminary carbonization at a specific carbonization temperature condition, then uses a certain amount of phosphoric acid, zinc chloride and water to make an activator aqueous solution for soaking, and then activates it at a specific activation temperature condition, Finally, it is washed and dried to obtain betel nut sludge activated carbon, which has the advantages of rich pore structure, large specific surface area, strong iodine adsorption capacity, and high yield. Moreover, the preparation method of the present application has the characteristics of low energy consumption and simple operation, so the preparation method of the present application is suitable for wide application, and can be preferably used as an adsorbent for wastewater treatment, gas purification technology and energy storage, and realizes waste treatment and resource utilization. use.

(2) Among them, in the carbonization process of this application, at a specific temperature (700-800 ° C), and nitrogen is used to fill the isolated air, the mixed material of betel nut and sludge can effectively prevent oxidation and excessive ablation during pyrolysis. During this process, volatiles and extractable organic compounds are removed. Therefore, the aromaticity and condensed carbon of the material can be enhanced during this carbonization process. Activated carbons prepared by the carbonization process, at which the microstructure of the carbon matrix is optimized, provide the basis for the porous structure of the activated carbons during the chemical activation step.

(3) The application soaks the carbonized betel nut and sludge mixed particles in a certain amount of activator aqueous solution (composed of ZnC1 ₂ , H ₃ PO ₄ and water) at room temperature, which can well enhance the carbonized carbon particles. Pore structure and specific surface area can reduce ash content and reduce energy consumption; it is also conducive to the formation of pores and the generation of volatile tar. Mainly use H ₃ PO ₄ to develop mesopore structure, while ZnCl ₂ develops microporous structure; among them, ZnC1 ₂ and H ₃ PO ₄ can dehydrate, can promote pyrolysis reaction, reduce the emission of soot gas, and produce graphite with a large number of micropores Crystal structure.

(4) This application adopts specific activation temperature and activation time to further control the micropore and mesopore structure of activated carbon.

(5) The method can effectively reduce the preparation cost of the activated carbon adsorbent, reduce the preparation process in the conventional process, improve the adsorption performance, reduce the reaction time, reduce the cost and equipment loss.

Description of drawings

Figure 1 (a) (500×) and (b) (5000×) scanning electron microscope images of activated carbon;

Fig. 2 _N2 adsorption-desorption isotherm (a) and pore size distribution (b) of activated carbon;

The influence of Fig. 3 activation temperature factor on activated carbon yield and adsorption iodine value;

The influence of Fig. 4 activation time factor on activated carbon yield and adsorption iodine value;

The influence of Figure 5 activator concentration factor on activated carbon yield and adsorption iodine value;

Figure 6 The influence of solid-liquid ratio factors on the yield and iodine value of activated carbon.

Detailed ways

In order to better understand the technical content of the present application, specific examples are provided below to further illustrate the present application.

The experimental methods used in the examples of the present application are conventional methods unless otherwise specified.

The materials and reagents used in the examples of the present application can be obtained from commercial sources unless otherwise specified.

Embodiment 1 betel nut sludge activated carbon preparation

1.1 Experimental equipment and chemicals

Reagents such as ZnCl ₂ , H ₃ PO ₄ , sodium thiosulfate, iodine, potassium iodide, and hydrochloric acid were all chemically pure; activated sludge, betel nut (local direct sampling).

Electric blast drying oven, tube furnace, crucible, electronic precision balance, nitrogen cylinder, glass instrument, etc.

1.2 Preparation of activated carbon

S1. Raw material preparation: wash the whole betel nut fruit with water to remove surface dirt, mix and dry the betel nut and sludge according to the mass ratio of 1:1 until the moisture content is 10%-20%, and the drying temperature is 105°C ±5°C; crush the dried product and pass through a 100-200 mesh sieve to obtain mixed particles of betel nut and sludge;

S2. High-temperature carbonization process: place the mixed particles of betel nut and sludge obtained in step S1 in a tube furnace, and carry out carbonization treatment in a nitrogen atmosphere. The heating rate was raised to 700°C for 60 minutes of carbonization, and finally cooled to room temperature to obtain carbonized betel nut and sludge mixed particles;

S3, activator soaking: take the carbonized betel nut and sludge mixed particles obtained in step S2 and mix them with the activator aqueous solution according to the mass volume ratio kg/L of 1:2.0, wherein the activator aqueous solution is composed of phosphoric acid, zinc chloride and water Prepared, the concentration of zinc chloride in the activator aqueous solution is 3.0 mol/L, the concentration of phosphoric acid is 3.0 mol/L, after mixing and stirring evenly, soaking at 20-33 ° C for 20 hours to obtain a mixed product;

S4. High-temperature activation: Put the mixed product activated in step S3 into a tube furnace, activate it in a nitrogen atmosphere, and heat it up to 800°C at a heating rate of 10-20°C/min from room temperature 20-33°C Activation for 1 hour; finally, cool the furnace to below 100°C, and continuously feed nitrogen into the tube furnace, and naturally cool to room temperature 20-33°C under a nitrogen atmosphere to take out the product to obtain a crude product;

S5, finished product: take the crude product obtained in step S4, carry out pickling, water washing, and dry, obtain target activated carbon product; Specific operation: the crude product obtained is washed repeatedly with 1M hydrochloric acid and distilled water, to remove ZnCl _and Other inorganic substances are then dried at 105°C to constant weight, which is the product of betel nut sludge activated carbon.

1.3 Results

1) calculate productive rate, the mass yield of gac is calculated as follows:

where m is the actual weight of the product activated carbon, m _MS and m _BN are the actual weights of the initial precursors. The results show that the betel nut sludge activated carbon product of embodiment 1 has a yield of 45.30%.

2) The iodine value is an index to characterize the adsorption capacity of activated carbon. The higher the iodine value, the stronger the adsorption capacity of the prepared activated carbon. Refer to the national standard GB/T 12496.8-2015 to test the iodine value of the product to obtain the microscopic surface information of activated carbon. The results show that the betel nut sludge activated carbon product of embodiment 1 has an iodine value of 723.19mg/g.

3) In order to understand the morphology characteristics of activated carbon, the morphology of pyrolyzed activated carbon under different magnifications, the surface morphology of the samples was studied using a scanning electron microscope (USA, thermoscientificVerios G4 UC).

As shown in Fig. 1, it can be observed that the betel nut sludge activated carbon has a well-developed irregular surface and is rich in loose texture. At the same time, there are many abundant pore structures on the surface of activated carbon, and many slit structures are formed. These slits facilitate the transfer of pollutants to the interior of the activated carbon, thereby increasing the adsorption capacity. The reason for this phenomenon is as follows: During the carbonization process, the activated carbon forms a preliminary network structure, which accelerates the further corrosion of the pores and the deeper pore structure during the activation process. This result shows that the areca nut sludge activated carbon prepared in Example 1 of the present application can effectively increase the surface area of activated carbon. Therefore, pyrolysis at 800 °C leads to more pores, widens the pores into macropores, and promotes the transformation of organic molecules into a well-developed porous structure.

4) Use a specific surface area analyzer (ASAP 2460, USA) to obtain the structural characteristics of the solid sample. The _N2 adsorption/desorption curves and pore characteristics were examined at low temperature (77K), and the surface area and pore volume were calculated using the brunauer-emmet-teller equation.

The adsorption and desorption isotherms and pore size distribution of the areca nut sludge activated carbon prepared in Example 1 of the present application are shown in Figure 2 . The adsorption of nitrogen in the low-pressure area may be related to the adsorption of the single layer of micropores, and the adsorption amount of nitrogen can reach 175cm ³ /g. Obvious hysteresis loops (0.4<P/P ₀ <1.0) were observed in the relative pressure region, which is considered to be characteristic of mesoporous materials. According to the IUPAC classification, the isotherm shows the H4 hysteresis loop, revealing the existence of parallel slit pores formed by the accumulation of sheet-like carbon. The pore size distribution can directly reveal the pore properties of activated carbon. The classification defined by IUPAC also includes micropores (diameter<2nm), mesopores (2-50nm) and macropores (diameter>50nm). According to the pore size distribution of activated carbon, a broad peak appears in the range of 5-50nm, indicating that activated carbon There are micropores and macropores. These results indicated that activated carbons with microporous and mesoporous structures were activated with a mixed chemistry of phosphoric acid and zinc chloride. The texture parameters of activated carbon are shown in Table 1. Among them, the S _tot and V _tot of the betel nut sludge activated carbon prepared in this application are 777.32m ² /g and 0.79cm ³ /g respectively, indicating that the prepared product has a relatively high specific surface area and can absorb pollutants well. In addition, the micropore volume of the areca nut activated carbon prepared by the present application and its proportion in the total pore volume are relatively large. This means that the pore structure and surface area of activated carbon are greatly improved due to the co-pyrolysis at 800 °C.

Table 1 Porous structure parameters of activated carbon

The results show that the areca nut sludge activated carbon prepared in this application has an irregular pore structure, the total surface area is 777.32m ² /g, and the pore volume is 0.79cm ³ /g.

Embodiment 2-activation temperature research

The activation process mainly includes the contact between the activator and the carbonized product and the change process of the pore structure after carbonization. Activation temperature is a key factor in the preparation of high-performance activated carbon. On the basis of Example 1, the activation temperatures were adjusted to 400°C, 500°C, 600°C, 700°C, 800°C, and 900°C. The iodine values and yields at different activation temperatures are shown in Figure 3.

As shown in Figure 3, the iodine value increases rapidly with the activation temperature from 400 °C to 800 °C, but when the temperature exceeds 800 °C, the iodine value decreases. This may be due to the increased diffusion of activated molecules into the interior of the carbonized product at higher temperatures; thus, more carbons were activated with phosphoric acid and hydrogen chloride, resulting in a rich pore structure. Excessively high activation temperature will also destroy the network structure of carbon, which should be avoided when synthesizing porous materials. In addition, the yield decreased with increasing activation temperature. This is because organic matter is continuously decomposed in the form of gas as carbon is consumed. In summary, the preferred activation temperature is 700-800°C, and the activation temperature is 800°C is the best condition for synthesizing activated carbon, its iodine value is 723.19mg/g, and the yield is 45.3%.

Example 3 - Activation Time Study

On the basis of Example 1, the activation time was adjusted to be 30-120 minutes respectively.

As shown in Figure 4, the iodine value of AC increased sharply from 545.69 mg/g to 634.72 mg/g before 60 minutes, and then decreased from 634.72 mg/g to 493.99 mg/g. A better iodine value of 634.72 mg/g was exhibited with a yield of 51% as the carbonized precursor was obtained at 600°C for 60 minutes. The reason may be that the shorter the activation time, the incomplete activation, and the lower the adsorption capacity; the highly developed pore structure needs enough time to stimulate micropore corrosion to meet the adsorption demand; and the prolonged activation time has a negative impact on the formation of pores, It even causes adjacent micropores to expand into pores. With the activation time ranging from 30 min to 120 min, a continuous decrease in yield could be observed, which may be due to further decomposition of organic and inorganic salts in the material. Ultimately, the preferred activation time is 50-70 minutes, and the most preferred activation time is 60 minutes.

Example 4 - Activator Concentration Study

In addition to reacting with the carbon precursor to generate pores, the activator also plays an important role in oxidation and dehydration during the preparation process. Some activators can remain in the micropores and mesopores to prevent pore collapse. This application studies the influence of different concentrations of mixed activator (phosphoric acid and zinc chloride) solutions on iodine value and yield. On the basis of Example 1, adjust the concentrations of zinc chloride and phosphoric acid in the activator aqueous solution to be 1.0mol/L, 1.5mol/L, 2.0mol/L, 2.5mol/L, 3.0mol/L, 3.5mol/L , 4.0mol/L, 4.5mol/L.

As shown in Figure 5, the experimental data show that with the increase of activator concentration, 3.0mol/L mixed activator can provide better conditions for the preparation of activated carbon with high iodine value (607.88mg/g), and its yield is 59.44%. This may be because the mixed activator reacts with the oxygen-containing functional groups on the surface of the previously carbonized product to form a large number of pores, which is different from the basic activator. The concentration of the mixed activator exceeding 3.0mol/L obviously leads to the decrease of the iodine value of the blended activated carbon. This can be explained as follows: too high a concentration of mixed activators has a negative impact on the iodine value, causing micropores to widen into macropores due to overactivation; moreover, crystals produced at high temperatures may block the pores. Changes in activator concentration had little effect on yield. From the perspective of cost and iodine value, the preferred concentration of zinc chloride in the activator aqueous solution is 2.0-3.5mol/L, the preferred concentration of phosphoric acid is 2.5-3.5mol/L, and 3.0mol/L is the optimum concentration.

Embodiment 5-solid-liquid ratio research

The solid-to-liquid ratio is critical to the development of pores in adsorbent materials. On the basis of Example 1, the solid-to-liquid ratio kg/L of the carbonized betel nut and sludge mixed particles and the activator aqueous solution were adjusted to be 1:1.0, 1:1.5, 1:2.0, 1:2.5, 1:3.0, 1:3.5.

As shown in Fig. 6, the iodine value of activated carbon varies with the change of solid-liquid ratio. When the solid-to-liquid ratio is less than 1:2.0, almost no activator participates in the formation of carbon skeleton and the development of pores, so the iodine value is relatively low. As long as the solid-to-liquid ratio exceeds 1:2.0, when the solid-to-liquid ratio is 1:2.0, the iodine value decreases and reaches the maximum value (624.9 mg/g), with a yield of 57.6%. However, a further increase in this ratio would widen the generated micropores into macropores, which may be closely related to the contact reaction between the carbon matrix and the activator. Considering the difference in yield, the preferred solid-to-liquid ratio is 1:2.0-3.0, and the most preferred solid-to-liquid ratio is 1:2.0.

Embodiment 6 betel nut sludge activated carbon preparation

S1, adopt the raw material that embodiment 1 prepares;

S2. High-temperature carbonization process: place the betel nut and sludge mixed particles obtained in Example 1 in a tube furnace, and carry out carbonization treatment in a nitrogen atmosphere. The tube furnace starts at a room temperature of 20-33° C. The heating rate was raised to 600°C for 90 minutes of carbonization, and finally cooled to room temperature to obtain carbonized betel nut and sludge mixed particles;

S3, activator soaking: take the carbonized betel nut and sludge mixed particles obtained in step S2 and mix the activator aqueous solution according to the mass volume ratio kg/L of 1:3.0, wherein the activator aqueous solution is composed of phosphoric acid, zinc chloride and water Prepared, the concentration of zinc chloride in the activator aqueous solution is 2.0mol/L, the concentration of phosphoric acid is 2.5mol/L, after mixing and stirring evenly, and soaking at 20-33°C for 12h, a mixed product is obtained;

S4. High-temperature activation: put the mixed product activated in step S3 into a tube furnace, and activate it in a nitrogen atmosphere. From a room temperature of 20-33°C, heat it up to 700°C at a heating rate of 10-20°C/min and keep it warm Activation for 2 hours; finally, cool the furnace to below 100°C, and continuously feed nitrogen into the tube furnace, and naturally cool to room temperature 20-33°C under a nitrogen atmosphere to take out the product to obtain a crude product;

S5, finished product: take the crude product obtained in step S4, carry out pickling, water washing, and dry, obtain target activated carbon product; Specific operation: the crude product obtained is washed repeatedly with hydrochloric acid and distilled water, to remove _ZnCl and other The inorganic matter is then dried at 105°C to constant weight, which is the betel nut sludge activated carbon product, with a yield of 48.00% and an iodine value of 661.15mg/g.

Example 7 Preparation of betelnut sludge activated carbon

S1. Raw material preparation: Wash the selected betel nuts with water to remove surface dirt, mix and dry the betel nuts and sludge until the moisture content is 10%-20%, and the drying temperature is 105°C±5°C; The product is crushed and passed through a 100-200 mesh sieve to obtain mixed particles of betel nut and sludge;

S2. High-temperature carbonization process: place the mixed particles of betel nut and sludge obtained in step S1 in a tube furnace, and carry out carbonization treatment in a nitrogen atmosphere. The heating rate was raised to 700°C for 30 minutes of carbonization, and finally cooled to room temperature to obtain carbonized betel nut and sludge mixed particles;

S3, activator soaking: take the carbonized betel nut and sludge mixed particles obtained in step S2 and mix them with the activator aqueous solution according to the mass volume ratio kg/L of 1:2.0, wherein the activator aqueous solution is composed of phosphoric acid, zinc chloride and water Prepared, the concentration of zinc chloride in the activator aqueous solution is 3.5 mol/L, the concentration of phosphoric acid is 2.5 mol/L, after mixing and stirring evenly, soaking at 20-33 ° C for 48 hours to obtain a mixed product;

S4. High-temperature activation: Put the mixed product activated in step S3 into a tube furnace, activate it in a nitrogen atmosphere, and heat it up to 800°C at a heating rate of 10-20°C/min from room temperature 20-33°C Activation for 0.5h; finally, cool the furnace to below 100°C, and continuously feed nitrogen into the tube furnace, and naturally cool to room temperature 20-33°C under a nitrogen atmosphere to take out the product to obtain a crude product;

S5, finished product: take the crude product obtained in step S4, carry out pickling, water washing, and dry, obtain target activated carbon product; Specific operation: the crude product obtained is washed repeatedly with hydrochloric acid and distilled water, to remove _ZnCl and other The inorganic matter is then dried at 105°C to constant weight, which is the betel nut sludge activated carbon product, with a yield of 57.62% and an iodine value of 675.94 mg/g.

Comparative example 1

The main difference between this Comparative Example 1 and Example 1 is that no betel nut was added in step S1, that is, sludge particles were obtained in step S1.

Comparative example 2

The main difference between this Comparative Example 1 and Example 1 is that no sludge is added in step S1, that is, betel nut particles are obtained in step S1.

Comparative example 3

The main difference between this Comparative Example 1 and Example 1 is that the carbonization temperature in step S2 is 500° C., and the carbonization time is 120 min.

Comparative example 4

The main difference between this Comparative Example 1 and Example 1 is that the activator aqueous solution in step S3 is prepared from zinc chloride and water with a concentration of 3.0 mol/L.

Comparative example 5

The main difference between this Comparative Example 1 and Example 1 is that the activator aqueous solution in step S3 is prepared from phosphoric acid and water, with a concentration of 3.0 mol/L.

Comparative example 6

The main difference between this Comparative Example 1 and Example 1 is that the activator aqueous solution in step S3 is prepared from zinc chloride, H ₂ SO ₄ and water, and the concentrations of zinc chloride and H ₂ SO ₄ are both 3.0 mol/L.

Comparative example 7

The main difference between this Comparative Example 1 and Example 1 is that the activator aqueous solution in step S3 is prepared from calcium chloride, phosphoric acid and water, and the concentrations of calcium chloride and phosphoric acid are both 3.0 mol/L.

The product yield and the iodine value result of above-mentioned embodiment 6-7, comparative example 1-7 are as follows table 2, and compare with embodiment 1:

the	Product yield (%)	Iodine value (mg/g)
Example 1	45.30	723.19
Example 6	48.00	661.15
Example 7	57.62	675.94
Comparative example 1	35.12	256.31
Comparative example 2	55.71	765.42
Comparative example 3	59.77	649.63
Comparative example 4	50.11	680.88
Comparative example 5	43.19	669.77
Comparative example 6	40.45	617.52
Comparative example 7	38.62	633.74

Referring to Comparative Example 1, it can be known that the preparation of activated carbon from sludge not only has a low yield, but also has a very low iodine value and low application value. Referring to Comparative Example 2, it can be seen that the preparation of activated carbon from betel nut has a high yield and high iodine value, but its preparation cost is high, which is not conducive to popularization and application. The betel nut sludge activated carbon product obtained in the embodiment of the present application has a strong iodine value adsorption capacity, and the product yield is maintained at about 50%, which has high application value, and at the same time, the production cost is low, which is conducive to popularization and application, and maximizes the use value of the sludge. , and good for the environment. Wherein, the iodine value adsorption capacity of Example 1 is relatively high, and Comprehensive Evaluation Example 1 is the preferred solution.

In addition, compared with Example 1, Comparative Example 3 has lower carbonization temperature and longer carbonization time, and the iodine value adsorption capacity of the obtained product is obviously decreased.

Compared with Example 1, comparative example 4 uses activator aqueous solution to only be made by zinc chloride and water, comparative example 5 uses activator aqueous solution to only be made by phosphoric acid and water, comparative example 6 utilizes sulfuric acid to replace phosphoric acid, comparative example 7 Calcium chloride replaces zinc chloride, and the iodine value adsorption capacity of its obtained product all drops obviously. This application uses a certain amount of activator aqueous solution (composed of ZnC1 ₂ , H ₃ PO ₄ and water) for soaking to effectively improve the performance of betel nut sludge activated carbon.

Comparative example 8

Document ^[1] prepared activated carbon by blending coconut shell and sludge. The iodine value of the areca nut sludge activated carbon prepared by the application was compared with the coconut shell sludge activated carbon prepared by the document ^[1] .

[1] Bing Yang, Yucheng Liu, Qingling Liang, Mingyan Chen, Lili Ma.Evaluation of activated carbon synthesized by one-stage and two-stage co-pyrolysis from sludge and coconut shell[J].Ecotoxicology and Environmental Safety,2019, 170:

The result shows that the iodine value of the areca nut sludge activated carbon prepared by the present application is obviously higher than that of the coconut shell sludge activated carbon.

The above is only a preferred embodiment of the application, and is not intended to limit the application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the application should be included in the application. within the scope of protection.

Claims (10)

1. A kind of method that utilizes betel nut and sludge is that material is prepared gac, is characterized in that, comprises the following steps:

   S1. Raw material preparation: mix and dry areca nuts and sludge, pulverize and sieve to obtain mixed particles of betel nuts and sludge;

   S2, high-temperature carbonization: place the betel nut and sludge mixed particles obtained in step S1 in a tube furnace, and carry out carbonization initial treatment in a nitrogen atmosphere. The carbonization temperature is 600-700 ° C, and the carbonization time is 30-90 minutes. Mixed granules of betel nut and sludge;

   S3, activator soaking: get the betel nut after the carbonization of step S2 and the mixed sludge of sludge and mix with activator aqueous solution, described activator aqueous solution is made by phosphoric acid, zinc chloride and water, the content of zinc chloride in described activator aqueous solution The concentration is 2.0-3.5mol/L, and the concentration of phosphoric acid is 2.5-3.5mol/L; the mass volume ratio of the betel nut and sludge mixed particles to the activator aqueous solution is 1:2.0-3.0, and soaked for 12 -48h, obtain mixed product;

   S4. High-temperature activation: put the mixed product activated in step S3 into a tube furnace, and activate it in a nitrogen atmosphere, wherein the activation temperature is 700-800°C, the activation time is 0.5-2h, and the crude product is obtained after cooling;

   S5. Finished product: pickling the crude product in step S4, washing with water, and drying to obtain the target activated carbon product.
2. The method for preparing activated carbon using areca nuts and sludge as materials according to claim 1, characterized in that, in step S1, areca nuts and sludge are mixed and dried until the moisture content is 10%-20%.
3. The method for preparing activated carbon using areca nuts and sludge as materials according to claim 1, characterized in that, in step S1, the mesh size of the sieve is 100-200 mesh.
4. The method for preparing activated carbon using areca nuts and sludge as materials according to claim 1, characterized in that, in step S2, carbonization is carried out by raising the temperature to 600-700°C at a heating rate of 10-20°C/min.
5. The method for preparing activated carbon using areca nuts and sludge as materials according to claim 1, characterized in that, in step S3, the soaking temperature is 20-33°C.
6. The method for preparing activated carbon using betel nut and sludge as materials according to claim 1, characterized in that in step S4, the temperature is raised to 700-800°C at a heating rate of 10-20°C/min for activation.
7. The method for preparing activated carbon using areca nuts and sludge as materials according to claim 1, characterized in that the specific operation of step S5 is as follows: the crude product is repeatedly washed with hydrochloric acid and distilled water to remove inorganic substances, and then dried at 105 ° C to constant Heavy.
8. The method for preparing activated carbon by utilizing betel nut and sludge according to claim 1, characterized in that, in step S3, the concentration of zinc chloride in the aqueous solution of the activator is 3.0mol/L, and the concentration of phosphoric acid is 3.0mol /L; the mass volume ratio of the betel nut and sludge mixed particles to the activator aqueous solution kg/L is 1:2.0.
9. The method for preparing activated carbon using areca nuts and sludge as materials according to claim 8, characterized in that, in step S3, the soaking time is 20 hours.
10. The method for preparing activated carbon using betel nut and sludge as materials according to any one of claims 1-9, characterized in that, in step S4, the activation temperature is 800° C., and the activation time is 1 h.

Images