CN106744949A - A kind of method for preparing activated carbon as raw material with sesame stalk - Google Patents

Abstract

The invention relates to the field of activated carbon preparation, in particular to a method for preparing activated carbon by using sesame stalks as raw materials. The sesame stalks are washed with water, dried, crushed, soaked, dried, activated by carbonization, pickled, washed with water, and finally dried and ground to obtain the activated carbon. The present invention uses sodium hydroxide, which has an outstanding pyrolysis effect on biomass, is cheap and environmentally friendly, as an activator, and can reduce the production cost of activated carbon while overcoming the environmental pollution caused by traditional activators ZnCl ₂ and H ₃ PO ₄ ; While the activated carbon can provide high adsorption performance, its bulk density is high, which is better than the bulk density of activated carbon prepared by traditional straw production.

Description

A kind of method that uses sesame straw as raw material to prepare activated carbon

technical field

The invention relates to the field of preparation of activated carbon, in particular to a method for preparing activated carbon by using sesame stalks as raw materials.

Background technique

In recent years, as the environmental problems caused by solid waste have become more and more prominent, China has paid more and more attention to the management of solid waste, and adopted management measures with the main goals of reducing the amount and turning them into resources. China is one of the largest agricultural countries in the world, which produces a huge amount of biomass waste every year. On the one hand, the huge amount of biomass waste can be used as a substitute for traditional energy, and it can also be used to produce various materials, such as adsorbents and chemical The raw material of the product. Commonly used biomass conversion technologies include heat treatment and biological treatment, and pyrolysis is considered to be an effective way to recycle biomass. Pyrolysis refers to a series of continuous cracking reactions of organic matter in vacuum or inert atmosphere to produce solid char, liquid and gaseous products. The output of these components depends on the raw materials and pyrolysis process conditions, usually low and medium pyrolysis temperature and slow heating rate are conducive to the formation of fixed char.

Activated carbon is an extremely important porous material, which is widely used in many industrial fields, such as energy storage, water purification, petrochemical, bioengineering, and environmental protection. In addition, activated carbon can reduce the impact of climate change and increase the yield of major crops, so it is also widely used in the field of agriculture. However, its production cost remains high, so it is particularly important to obtain cheap and high-quality raw materials from a wide range of sources. CN104843700A discloses a powdered activated carbon prepared from peat compounded with corn stalks, the highest methylene blue adsorption value is only 280 mg/g; CN101708845A discloses a method for preparing activated carbon from rice husks and straws, It needs to be treated with phosphoric acid, and the methylene blue adsorption rate is only 135mg/g.

Sesame is one of the main economic crops in China, and the sesame stalks produced by it are as high as 36 million tons every year. The traditional treatment of sesame straw is open burning, which not only causes serious air pollution but also wastes resources. In fact, sesame straw has a high carbon content, low ash content and appropriate hardness, and is an ideal precursor for the production of activated carbon. However, there are no public reports on the use of sesame straw to prepare activated carbon at home and abroad. The production process of activated carbon is mainly divided into physical activation method and chemical activation method. The physical activation method is to complete the preparation of activated carbon through two steps of carbonization and activation. The chemical activation method completes carbonization-activation in one step, and the temperature of carbonization is lower than that of the physical activation method. It can also improve the pores of activated carbon and increase the yield of activated carbon. Overall, activated carbon prepared by chemical activation is superior to physical activation and has more commercial value.

In addition to its excellent adsorption performance, the physical and chemical indicators of activated carbon directly affect the performance of activated carbon and subsequent transportation and application. Generally, the higher the bulk density, the better the filtration performance of activated carbon and the easier it is to store, transport and recycle. cause dust pollution. But usually the activated carbon prepared from plant stalks has a relatively low bulk density. For example, a hemp stalk activated carbon and its preparation method disclosed in CN101181993A have a bulk density of 0.25-0.30 g/cm ³ .

Therefore, it is of great significance to develop an activated carbon with high methylene blue adsorption value and high bulk density prepared from biomass straw, that is, sesame straw.

Contents of the invention

The present invention aims at the high price of existing activated carbon products, the current situation of shortage of raw materials, and the shortcomings of the activated carbon prepared by conventional plant straws with low bulk density and low methylene blue adsorption value; it provides a method for preparing activated carbon with sesame straw as raw material, thereby reducing the Burning straw will aggravate the impact of smog, expand the outlet for turning straw into treasure, realize resource recycling, and promote the development of a low-carbon economy.

The present invention achieves the above object through the following technical solutions, a method for preparing activated carbon with sesame stalks as a raw material, comprising the following steps:

1) Wash the sesame stalks with water twice to remove dust, then air-dry them naturally, and dry them at 105°C for 4 hours;

2) Crushing the dried sesame straw to 60-80 mesh to obtain sesame straw particles;

3) Mix the sesame straw particles treated in step 2) with sodium hydroxide (purity 99%) at a weight ratio of 1:0.5-4, add deionized water for stirring, and then place in a water bath shaker to shake at room temperature Mix it evenly for 60 minutes, and filter out the solution after standing for 24 hours; dry the soaked sesame straw particles at 100°C until completely dry;

4) Carbonize and activate the sesame straw particles treated in step 3), and then cool to obtain a sample before pickling; the carbonization activation temperature is 400-900° C., and the carbonization activation time is 30-180 minutes;

5) Cook the sample before pickling with 10wt% hydrochloric acid aqueous solution at 60°C for 30 minutes, then fully rinse with distilled water until the pH of the filtrate is 6.5 to 7.5, dry at 120°C after rinsing, and put it into a desiccator after drying Cool in the middle, and then grind to 200 mesh to get activated carbon.

A method for preparing activated carbon using sesame stalks as a raw material according to the present invention, its further technical solution may be that the weight ratio of sesame stalk particles to sodium hydroxide in step 3) is 1:1-3;

A method for preparing activated carbon using sesame stalks as a raw material according to the present invention, its further technical solution can be, step 4) the carbonization activation time is 60 to 140 minutes;

The method for preparing activated carbon by using sesame stalks as a raw material according to the present invention has a further technical proposal as follows: Step 4) The carbonization activation temperature is 600-800°C.

A method for preparing activated carbon using sesame stalks as a raw material according to the present invention, its further technical solution may be that the weight ratio of 10wt% hydrochloric acid aqueous solution to the sample before pickling in step 5) is 8-10:3.

Compared with prior art, the present invention has following advantage:

1) For the first time, the present invention utilizes the biomass waste sesame stalks produced during the harvesting process of the agricultural economic crop sesame, and the raw materials are easy to obtain and cheap, which can make up for the defect of limited quantity of husk biomass and reduce the production cost of activated carbon;

2) Sodium hydroxide, which has an outstanding pyrolysis effect on biomass, is cheap and environmentally friendly, is used as an activator, which can reduce the production cost of activated carbon while overcoming the environmental pollution caused by traditional activators ZnCl ₂ and H ₃ PO ₄ ;

3) The method requires less investment in equipment, simple operation, and low energy consumption. While the obtained activated carbon can provide high adsorption performance, its bulk density is high, which is better than that of activated carbon prepared by traditional straw production.

Description of drawings

Figure 1 is a process flow chart for the preparation of sesame straw activated carbon.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that these descriptions are exemplary only, and are not intended to limit the scope of the present invention.

Example 1

The sesame straws taken from the Hanshan area of Anhui Province were washed twice with clean water to remove dust, and air-dried under natural conditions; the air-dried sesame straws were dried at 105°C for 4 hours, and the dried sesame straws were crushed to 60-80 meshes; Mix 10g of sesame straw granules and NaOH granules at a ratio of 1:2, add 100ml of deionized water and stir evenly, place the mixture in a water bath shaker and shake it at room temperature for 60 minutes to make it evenly mixed, after standing for 24h, filter out the solution and impregnate the sample Dry at 100°C until completely dry; the mixed sample is placed in a tube electric furnace at a heating rate of 5°Cmin ^-1 to 640°C for carbonization activation, the nitrogen flow rate is 30mLmin ^-1 , and the maintenance time is 87 minutes; after cooling 1. Boil with 10% hydrochloric acid at 60°C for 30 minutes (the weight ratio of 10% hydrochloric acid to sample weight is 10:3), then fully rinse with distilled water until the pH of the filtrate is 6.5 to 7.5, and dry at 120°C. Cool and grind to 200 mesh to obtain activated carbon. The prepared activated carbon methylene blue has an adsorption value of 224 mg/g and a bulk density of 0.46 g/cm ³ .

Example 2

Rinse the sesame stalks taken from the Hanshan area of Anhui twice with clean water to remove dust, and air-dry them under natural conditions; dry the air-dried sesame stalks at 105°C for 4 hours, and the dried sesame stalks are broken to about 60-80 mesh; Take 10g of sesame straw granules and NaOH granules and mix them at a ratio of 1:3, add 100ml of deionized water and stir evenly, place the mixture in a water bath shaker and shake it at room temperature for 60 minutes to make it evenly mixed, after standing for 24h, filter out the solution and impregnate The sample was dried at 100°C until it was completely dry; the mixed sample was placed in a tube electric furnace at a heating rate of 5°Cmin ^-1 to 800°C for carbonization activation, the nitrogen flow rate was 30mLmin ^-1 , and the holding time was 120 minutes; Cool, boil with 10% hydrochloric acid at 60°C for 30 minutes (the weight ratio of 10% hydrochloric acid to sample weight is 8:3), then fully rinse with distilled water until the pH of the filtrate is 6.5-7.5, and dry at 120°C , cooled, and ground to obtain activated carbon. The prepared activated carbon methylene blue has an adsorption value of 321 mg/g and a bulk density of 0.52 g/cm ³ .

Example 3

Rinse the sesame stalks taken from the Hanshan area of Anhui twice with clean water to remove dust, and air-dry them under natural conditions; dry the air-dried sesame stalks at 105°C for 4 hours, and the dried sesame stalks are broken to about 60-80 mesh; Take 10g of sesame straw granules and NaOH granules and mix them according to 1:2.5, add 100ml of deionized water and stir evenly, place the mixture in a water bath shaker and shake it at room temperature for 60 minutes to make it evenly mixed, after standing for 24h, filter out the solution and impregnate The sample was dried at 100°C until it was completely dry; the mixed sample was placed in a tube electric furnace at a heating rate of 5°Cmin ^-1 to 800°C for carbonization activation, the nitrogen flow rate was 30mLmin ^-1 , and the holding time was 120 minutes; Cool, boil with 10% hydrochloric acid at 60°C for 30 minutes (the weight ratio of 10% hydrochloric acid to sample weight is 10:3), then fully rinse with distilled water until the pH of the filtrate is 6.5-7.5, and dry at 120°C , cooled, and ground to obtain activated carbon. The prepared activated carbon has an adsorption value of methylene blue of 288 mg/g and a bulk density of 0.43 g/cm ³ .

Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions and alterations could be made hereto without departing from the spirit and scope of the invention.

Claims (6)

1. a kind of method for preparing activated carbon as raw material with sesame stalk, comprises the following steps：

1) sesame stalk washes natural air drying after 2 removal dusts, is dried 4 hours at 105 DEG C；

2) sesame stalk after drying is crushed to 60-80 mesh and obtains sesame stalk particle；

3) by step 2) sesame stalk particle and NaOH after treatment is by weight being 1:0.5~4 mixing, adds deionization Water is stirred, and is subsequently placed in water bath shaker to shake at room temperature 60 minutes and is allowed to well mixed, stand filter after 24h it is molten Liquid；By the sesame stalk particle of dipping at 100 DEG C to being completely dried；

4) by step 3) the sesame stalk particle after treatment carries out carbonization-activation, then carries out cooling down obtaining sample before pickling；It is described 400~900 DEG C of carbonization-activation temperature, 30~180 minutes carbonization-activation time；

5) aqueous hydrochloric acid solution that sample concentration before pickling is 10wt% is boiled 30 minutes at 60 DEG C, it is then abundant with distilled water Rinsing is 6.5~7.5 to filtrate pH, and 120 DEG C of drying after rinsing are put into drier after drying and are cooled down, and are then ground to 200 mesh obtain final product activated carbon.

2. method according to claim 1, it is characterised in that：Step 3) in sesame stalk particle and NaOH weight ratio It is 1:1~3.

3. method according to claim 1, it is characterised in that：Step 4) 60~140 minutes carbonization-activation time.

4. method according to claim 1, it is characterised in that：Step 4) 600~800 DEG C of carbonization-activation temperature.

5. method according to claim 1, it is characterised in that：Step 5) in 10wt% aqueous hydrochloric acid solution and pickling before sample The weight ratio of product is 8~10:3.

6. method according to claim 1, it is characterised in that：The activated carbon bulk density prepared is 0.43-0.52g/ cm³。