CN103408011A - Preparation method of sargassum horneri matrix activated carbon - Google Patents

Abstract

The invention discloses a preparation method of sargassum horneri matrix activated carbon. The preparation method comprises the following steps: (1), mixing sargassum horneri powder and activator with water for impregnating treatment for 2-24 h; (2), placing the mixture I under an inert atmosphere, raising the temperature of the mixture I to 400-600 DEG C according to a rate of 10-30 DEG C/min; performing activating treatment on the mixture I for 1-3 h; then washing the mixture I with hot acid solution and hot distilled water in sequence until the pH value of the mixture does not change; drying the mixture I to obtain a product A; (3), mixing the product A with boiling oxidant solution to enable the product A to react with the boiling oxidant solution for 1-3 h; then, washing the mixture II with hot distilled water until the pH value of the mixture II does not change; drying the mixture II to obtain a product B; (4), performing high-heat treatment on the product B at 300-500 DEG C, so as to obtain the sargassum horneri matrix activated carbon. The activated carbon prepared through the preparation method has the advantages that most pores are mesoporous, the pores are well-developed, the ash content is low, and the adsorbability to hexavalent chromium is higher.

Description

A kind of preparation method of copper algae-based activated carbon

technical field

The invention relates to a method for preparing activated carbon, which is characterized in that copper algae is used as a raw material to prepare activated carbon.

Background technique

Activated carbon is a kind of porous substance, which has the advantages of developed pore structure, huge specific surface area, abundant surface functional groups, and stable chemical properties, so it has been widely used. However, the activated carbon industry is still basically a "resource-consuming" industry. Therefore, the source of raw materials is an important reason that restricts the development of the activated carbon industry. At present, the raw materials for activated carbon preparation at home and abroad are mainly divided into: coal, wood and industrial products, and industrial and agricultural waste. In recent years, traditional raw materials are limited by issues such as resources, energy and the environment, making the search for activated carbon raw materials gradually shift from land to sea. A large number of studies have shown that macroalgae have good adsorption properties for heavy metals and organic pollutants, and often have high cellulose content, as well as advantages such as fast growth, large yield, easy harvesting, and no competition for land with food. The field of activated carbon preparation has great potential. Internationally, since 2009, two large seaweeds, Sargassum Longifolium (S.L.) and Hypnea Valentiae (H.V.), have been used as raw materials to control the pore size distribution of activated carbon by adjusting the ratio of activator zinc chloride to produce activated carbon with mainly mesopores. , and has the advantages of high mechanical strength and low ash content; using Posidonia Oceanic (L.) fiber as raw material, activated carbon is prepared by steam activation method and zinc chloride activation method. But on the whole, there are few related reports on the use of macroalgae as raw materials for the preparation of activated carbon, and there are no reports on the specific surface area of the prepared activated carbon using copper algae as raw materials.

Activated carbon is usually divided into two steps: carbonization and activation. The traditional chemical activation method is highly corrosive to equipment, pollutes the environment, and there are chemical activators in the activated carbon, so its application is limited. The most important factors in the carbonization process are the final temperature of carbonization and the heating rate of carbonization. The quality of carbonization products is also closely related to the chemical properties and physical particle size of raw materials. Activation temperature is one of the main factors that determine the formation rate of activated carbon pore structure. The main reaction of activation is a reversible endothermic reaction. Increasing the reaction temperature is conducive to the forward reaction. However, if the temperature is too high, the pore structure of activated carbon will easily change, the micropores will decrease, the macropores will increase, the strength will decrease, and the yield will decrease. Therefore, ensuring yield, reducing energy consumption, optimizing process, and improving quality are always the basic requirements for activated carbon production.

Copper algae (Sargassum Horneri) is a dominant species in the southeast coast of my country, and has been listed as the preferred species for the restoration of warm sea temperate marine ecological environment and one of the important species for rebuilding seabed algae farms. However, the industrialization and resource utilization of copper algae are still far from mature and urgently need to be developed. Therefore, the use of copper algae to prepare activated carbon has become a frontier topic in the development and application of copper algae. The research results obtained in this patent can provide the basis and reference for the research of macroalgae-based activated carbon, and also make preliminary preparations for the urgently needed industrial utilization after large-scale breeding of non-edible macroalgae in marine ecological restoration projects.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for preparing copper algae-based activated carbon. The activated carbon prepared by this method has mainly mesopores, well-developed pores, low ash content, and high adsorption performance for hexavalent chromium.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

A method for preparing activated carbon with copper algae, comprising the steps of:

(1) Mix copper algae powder, activator and water, and perform immersion treatment for 2 to 24 hours; the activator is zinc chloride or phosphoric acid or potassium hydroxide; wherein the weight ratio of copper algae powder to the activator is 1: 3~5;

(2) Put the impregnation in an inert atmosphere and raise the temperature to 400-600°C at a rate of 10-30°C/min, perform an activation treatment for 1-3 hours, then wash with hot acid solution, and then wash with hot distilled water until the pH remains unchanged , drying to obtain product A;

(3) Mix product A with boiling oxidant solution, react for 1-3 hours, then wash with hot distilled water until the pH remains constant and dry to obtain product B;

(4) The product B is subjected to high-temperature heat treatment at 300-500°C for 1-3 hours to obtain copper algae-based activated carbon products.

In the present invention, the copper algae powder can be obtained by the following treatment: the collected fresh copper algae is washed with water to remove impurities, cut after drying, and pulverized in a pulverizer. head.

In the step (1), the activator is zinc chloride or phosphoric acid or potassium hydroxide, preferably zinc chloride or phosphoric acid, most preferably zinc chloride. The impregnation treatment is carried out at room temperature under stirring. The weight ratio of the copper algae powder to water is generally 1:5.

In the step (2), the inert atmosphere is preferably nitrogen, and the gas flow rate is 50-150 L/h. The hot acid solution for washing is preferably a boiled hydrochloric acid solution. The temperature of hot distilled water for washing is generally 70-100°C.

In the step (3), the oxidizing agent is 10-50% by mass fraction of nitric acid or sulfuric acid or hydrochloric acid solution, preferably nitric acid solution. In every 1g of product A, the addition amount of oxidizing agent solution is 5～20mL. The temperature of hot distilled water for washing is generally 70-100°C. The oxidation reaction is carried out at room temperature.

In the steps (2) and (3), the drying is carried out at a temperature of 100-110° C., and the drying time is 3-24 hours.

The copper algae-based activated carbon product prepared by the method of the present invention has the following specifications: specific surface area ^1014-2314m2 ·g ^-1 , iodine value 1005.7-1197.8mg·g ^-1 , methylene blue value 9.0-12.0mL·0.1g ^-1 , the decolorization rate of caramel is 90-115%, the saturated adsorption capacity of hexavalent chromium is 24.2-83.5 mg·g ^-1 , and the ash content is 0.2-0.8%.

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

(a) The present invention uses copper algae as the raw material for the preparation of activated carbon. The oxygen content of copper algae is high. During the carbonization process, due to the breakage of oxygen-containing functional groups, the oxygen released in the form of H ₂ O, CO, and CO ₂ further improves the expansion. Pore performance; at the same time, due to the high oxygen content, it is easy to combine with hydrogen to form water during thermal decomposition, and the generated tar or other colloids will be relatively small.

(b) The present invention adopts further oxidative modification and high-temperature heat treatment on the activated carbon after chemical activation, and the content of acidic oxygen-containing functional groups such as carboxyl, phenolic hydroxyl, and lactone groups on the surface of the activated carbon is significantly increased, and it is found that after high-temperature treatment under appropriate conditions, certain After a period of time, the pore blockage caused by oxidation can be better improved without destroying the oxidation functional group, so that the activated carbon has high specific surface area, strong specific adsorption performance and With the advantages of low ash content, it is especially suitable for the purification and adsorption of wastewater containing heavy metal ions. At the same time, it can also be used for the adsorption and purification process of other gases.

Description of drawings

Fig. 1 is the scanning electron micrograph of the copper algae-based activated carbon of example 1-4 respectively, wherein A-embodiment 1, B-example 2, C-example 3, D-example 4.

Detailed ways

The technical characteristics of the present invention are further described below in conjunction with examples, but the protection scope of the present invention is not limited thereto.

Example 1

The copper algae collected in the Wenzhou sea area in southern Zhejiang were simply air-dried, washed with tap water to remove salt and impurities, then washed several times with deionized water, drained, and dried at 100°C for 24 hours to constant weight. The dried copper algae is crushed again, and the powder of 20-40 meshes is screened out. Weigh 10g of dry copper algae powder, add 100g of zinc chloride solution with a mass fraction of 50%, and stir at 25°C for 2h. Then the impregnated mixture was transferred to a vacuum tube furnace, and under the protection of nitrogen with a flow rate of 120 L·h ^-1 , the temperature was raised to 500°C at a rate of 10°C·min ^-1 and activated for 1 h. The activated sample was boiled with 1 mol L ^- 1 HCl solution for 30 min, washed several times with boiled HCl solution, washed with deionized water at 95°C until the pH remained constant, and then baked at 100°C for 24 h to constant weight. The product A ₁ is obtained.

Add 10mL of 10% boiling nitric acid solution to 1g of product _A1 , and let it stand for oxidation at 25°C for 2h. The oxidized sample was washed with deionized water at 95°C until the pH remained constant, and then baked at 100°C for 24 hours to constant weight to obtain product B ₁ . Put the product B ₁ into a muffle furnace at 300°C for high-temperature heat treatment for 2 hours to obtain the activated carbon product C ₁ , whose properties are shown in Table 1.

Example 2

The copper algae collected in the Wenzhou sea area in southern Zhejiang were simply air-dried, washed with tap water to remove salt and impurities, then washed several times with deionized water, drained, and dried at 100°C for 24 hours to constant weight. The dried copper algae is crushed again, and the powder of 20-40 meshes is screened out. Weigh 10g of dry copper algae powder, add 100g of zinc chloride solution with a mass fraction of 50%, and stir at 25°C for 10h. Then the impregnated mixture was transferred to a vacuum tube furnace, and under the protection of nitrogen with a flow rate of 100L·h ^-1 , the temperature was raised to 600°C at a rate of 20°C·min ^-1 for activation for 3h. The activated sample was boiled with 1 mol L ^- 1 HCl solution for 30 min, washed several times with boiled HCl solution, washed with deionized water at 95°C until the pH remained constant, and then baked at 100°C for 24 h to constant weight. The product _A2 is obtained.

Add 10mL of 20% boiling nitric acid solution to 1g of product _A2 , and let it stand for oxidation at 25°C for 1h. The oxidized sample was washed with deionized water at 95°C until the pH remained unchanged, and then baked at 100°C for 24 hours to constant weight to obtain product B ₂ . The product B ₂ was placed in a muffle furnace at 400°C for high temperature heat treatment for 3 hours to obtain the activated carbon product C ₂ , and its properties are shown in Table 1.

Example 3

The copper algae collected in the Wenzhou sea area in southern Zhejiang were simply air-dried, washed with tap water to remove salt and impurities, then washed several times with deionized water, drained, and dried at 100°C for 24 hours to constant weight. The dried copper algae is crushed again, and the powder of 20-40 meshes is screened out. Weigh 10g of dry copper algae powder, add 100g of zinc chloride solution with a mass fraction of 30%, and stir at 25°C for 10h. Then the impregnation mixture was transferred to a vacuum tube furnace, and under the protection of nitrogen with a flow rate of 150 L·h ^-1 , the temperature was raised to 600°C at a rate of 30°C·min ^-1 and activated for 1 h. The activated sample was boiled with 1 mol L ^- 1 HCl solution for 30 min, washed several times with boiling HCl solution, washed with deionized water at 95°C until the pH remained constant, and then baked at 100°C for 24 h to constant weight. The product _A3 is obtained.

Add 10mL of 10% boiling nitric acid solution to 1g of product _A3 , and let it stand for oxidation at 25°C for 3h. The oxidized sample was washed with deionized water at 95°C until the pH remained unchanged, and then baked at 100°C for 24 hours to constant weight to obtain product B ₃ . Put the product B ₃ into a muffle furnace at 500°C for high-temperature heat treatment for 2 hours to obtain the activated carbon product C ₃ , whose properties are shown in Table 1.

Example 4

The copper algae collected in the Wenzhou sea area in southern Zhejiang were simply air-dried, washed with tap water to remove salt and impurities, then washed several times with deionized water, drained, and dried at 100°C for 24 hours to constant weight. The dried copper algae is crushed again, and the powder of 20-40 meshes is screened out. Weigh 10g of dry copper algae powder, add 100g of phosphoric acid solution with a mass fraction of 50%, and stir at 25°C for 10h. Then the impregnation mixture was transferred to a vacuum tube furnace, and under the protection of nitrogen with a flow rate of 100 L·h ^-1 , the temperature was raised to 400°C at a rate of 10°C·min ^-1 and activated for 1 h. The activated sample was boiled with 1 mol L ^- 1 HCl solution for 30 min, washed several times with boiled HCl solution, washed with deionized water at 95°C until the pH remained constant, and then baked at 100°C for 24 h to constant weight. The product _A4 is obtained.

Add 10mL of 30% boiling nitric acid solution to 1g of product _A4 , and let it stand for oxidation at 25°C for 2h. The oxidized sample was washed with deionized water at 95°C until the pH remained unchanged, and then baked at 100°C for 24 hours to constant weight to obtain product B ₄ . Put the product B ₄ into a muffle furnace at 400°C for high-temperature heat treatment for 1 hour to obtain the activated carbon product C ₄ , whose properties are shown in Table 1.

Example 5

The copper algae collected in the Wenzhou sea area in southern Zhejiang were briefly air-dried, washed with tap water to remove salt and impurities, then washed several times with deionized water, drained, and dried at 100°C for 24 hours to constant weight. The dried copper algae is crushed again, and the powder of 20-40 meshes is screened out. Weigh 10g of dry copper algae powder, add 100g of phosphoric acid solution with a mass fraction of 30%, and stir at 25°C for 10h. Then the impregnation mixture was transferred to a vacuum tube furnace, and under the protection of nitrogen with a flow rate of 100L·h ^-1 , the temperature was raised to 400°C at a rate of 20°C·min ^-1 for activation for 2h. The activated sample was boiled with 1 mol L ^- 1 HCl solution for 30 min, washed several times with boiling HCl solution, washed with deionized water at 95°C until the pH remained constant, and then baked at 100°C for 24 h to constant weight. The product _A5 is obtained.

Add 10mL of 20% boiling nitric acid solution to 1g of product _A5 , and let it stand for oxidation at 25°C for 3h. The oxidized sample was washed with deionized water at 95°C until the pH remained constant, and then baked at 100°C for 24 hours to constant weight to obtain product B ₅ . Put the product B ₅ into a muffle furnace at 300°C for high-temperature heat treatment for 2 hours to obtain the activated carbon product C ₅ , whose properties are shown in Table 1.

Structural performance test of copper algae-based activated carbon:

The specific surface area of activated carbon was measured by ASAP2020 automatic adsorption instrument from American Micromeritics Company, and its specific surface area was calculated by the standard BET method. The surface morphology and pore structure of activated carbon were observed with a Hitachi S-4700 scanning electron microscope from Hitachi, Japan.

The determination of activated carbon ash content is carried out according to the "GB/T12496.3-1999" determination method of wood activated carbon ash content; The determination of the rate is carried out according to the "GB/T12496.9-1999" method for the determination of the caramel decolorization rate of woody activated carbon; the determination of the adsorption value of methylene blue is carried out according to the "GB/T12496.10-1999" method for the determination of the iodine adsorption value of woody activated carbon; Cr ⁶⁺ The concentration was determined by o-phenylcarbazide chromogenic method, and the Cr ⁶⁺ concentration was calculated according to the Lambert-Beer law, and the adsorption capacity of activated carbon was calculated.

Table 1 Performance of copper algae-based activated carbon

Claims (8)

1. the preparation method of a Sargassum horneri matrix activated carbon, comprise the steps:

(1) Sargassum horneri powder, activator and water are mixed, carry out dip treating 2～24h; Described activator is zinc chloride or phosphoric acid or potassium hydroxide; Wherein the weight ratio of Sargassum horneri powder and activator is 1:3～5;

(2) macerate is placed in to the speed by 10～30 ℃/min under inert atmosphere and is warming up to 400～600 ℃, carry out the activation treatment of 1～3h, then use the hot acid solution washing, the reusable heat distilled water wash is constant to pH, and drying obtains product A;

(3) product A is mixed with the oxidizing agent solution of boiling, reaction 1～3h, then wash the constant and dry product B that obtains to pH with hot distilled water;

(4) product B is carried out to high-temperature heat treatment 1～3h in 300～500 ℃, namely obtain Sargassum horneri matrix activated carbon product.

2. according to preparation method claimed in claim 1, it is characterized in that: the median size of the Sargassum horneri powder described in step (1) is 20～100 orders.

3. according to preparation method claimed in claim 1, it is characterized in that: the activator described in step (1) is zinc chloride or phosphoric acid.

4. according to preparation method claimed in claim 1, it is characterized in that: the inert atmosphere described in step (2) is nitrogen.

5. according to preparation method claimed in claim 1, it is characterized in that: the oxidizing agent solution described in step (3) is nitric acid or sulfuric acid or the hydrochloric acid soln of 10～50% massfractions.

6. according to preparation method claimed in claim 1, it is characterized in that: the oxidizing agent solution described in step (3) is the salpeter solution of 10～50% massfractions.

7. according to the described preparation method of claim 1 or 5, it is characterized in that: in step (3), in every 1g product A, the add-on of oxidizing agent solution is 5～20mL.

8. according to preparation method claimed in claim 1, it is characterized in that: the drying in step (2), (3) is carried out respectively under the temperature condition of 100～110 ℃, and be 3～24h time of drying.

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