CN114768765A - A kind of preparation method of lignite-based magnetic activated carbon and wastewater treatment method - Google Patents

Abstract

The invention provides a preparation method of brown coal-based magnetic activated carbon, which comprises the following steps: firstly, lignite is pretreated to obtain lignite powder; secondly, dipping and mixing, namely mixing the lignite powder with an iron-based activator; thirdly, drying and grinding; fourthly, high-temperature pyrolysis is carried out; and step five, drying treatment. The method takes lignite as a raw material, adopts a chemical activation means to carry out catalytic pyrolysis to prepare the coal-based activated carbon, and adopts the prepared coal-based activated carbon as an adsorbent to efficiently adsorb heavy metal ions in the wastewater.

Description

A kind of preparation method of lignite-based magnetic activated carbon and wastewater treatment method

technical field

The invention relates to the technical field of industrial wastewater treatment, in particular to a preparation method of lignite-based magnetic activated carbon and its application in the treatment of heavy metal ion wastewater.

Background technique

With the rapid development of industry and agriculture, water pollution caused by heavy metal ions such as lead, iron, cobalt, copper, nickel, chromium, and cadmium has become one of the most harmful water pollution problems in recent years. Heavy metal ions can exist stably in the water environment and cannot be degraded and destroyed, and when the accumulation of heavy metal ions in the human body reaches a certain limit, it will bring about a series of health problems such as damage to the central nervous system, developmental disorders and neurobehavioral disorders. question. Therefore, proper treatment of wastewater containing heavy metal ions can not only solve the problem of water pollution, but also has important value in properly solving the human health problems caused by wastewater pollution. At present, the methods for removing heavy metal ions in sewage mainly include traditional chemical precipitation method, ion exchange method, adsorption method, membrane filtration method, redox method, biological method, etc. Among them, the adsorption method is the most widely used. However, the research at this stage mainly focuses on the preparation of synthetic adsorbents from reagents, which is generally expensive and has poor adsorption effect.

Chinese patent 111318255A discloses a magnetic graphene oxide composite material, by reacting ferric chloride hexahydrate, sodium acetate, surfactant, ethylene glycol and graphene oxide to obtain Fe ₃ O ₄ @GO after the reaction; The Fe ₃ O ₄ @GO is mixed with the ferrous salt aqueous solution and acrylic acid to obtain a mixed solution, the mixed solution is ultrasonically dispersed and then passed into an inert gas and subjected to irradiation treatment; the irradiated product is subjected to magnetic Separate, wash and dry to obtain a magnetic graphene oxide composite. The magnetic graphene oxide composite material of the present invention can increase the adsorption sites of GO to improve its adsorption effect with heavy metal ions, but the preparation cost of the adsorbent is too high, the process is very complicated, and the process is not easy to control.

Chinese patent 113262764A invented an iron-based cellulose nanocomposite material with a three-dimensional network structure composed of nanocellulose and nano-zero valent iron. The material has high adsorption and reduction capacity for heavy metals and can effectively remove heavy metal ions in the water environment, but the preparation cost of the adsorbent is high and the process is complicated.

Chinese Patent No. 113244888A invented a lignite-based adsorbent that uses magnesium ions to modify demineralized coal samples, which can form more active sites for adsorbing organic dyes, thereby improving the ability of lignite-based adsorbents to absorb organic dyes. The adsorption performance of the modified lignite-based adsorption material can reach 95.56 mg/g, but its adsorption effect is still not ideal.

Therefore, it is of great significance to develop low-cost and high-efficiency adsorbents to adsorb heavy metal ions in industrial wastewater.

Lignite is a brown-black, dull low-rank coal between peat and bituminous coal. Since high-quality coal has almost been mined out, lignite has become the main coal used in my country. However, due to the low degree of coalification of lignite, a large amount of black ash will float in the air during combustion. It will lead to the increasingly serious smog problem in my country. Therefore, realizing the resource utilization, high efficiency and high value-added utilization of lignite has important application prospects for enhancing its application value. Compared with other raw materials, coal resources are widely available and cheap, and the coal-based activated carbon prepared from coal has high mechanical strength and high chemical stability. At present, the present invention proposes to use lignite as a raw material to prepare a coal-based activated carbon preparation method with excellent adsorption performance for heavy metal ions, simple preparation method and low preparation cost, and realizes high value-added utilization of lignite.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of lignite-based magnetic activated carbon, using lignite as a raw material, using chemical activation means to carry out catalytic pyrolysis to prepare a preparation method of coal-based activated carbon, and the prepared coal-based activated carbon as an adsorbent to efficiently adsorb waste water. The adsorption method of heavy metal ions is simple, and the obtained adsorbent has high adsorption performance.

In order to solve the above-mentioned technical problems, the present invention provides a preparation method of lignite-based magnetic activated carbon, which comprises:

The first step, lignite pretreatment, to obtain lignite pulverized coal;

The second step, impregnation mixing, mixing lignite powder and iron-based activator;

The third step is drying and grinding;

The fourth step, high temperature pyrolysis;

The fifth step is drying.

The first step is to put the lignite in an oven for drying, the drying temperature is 60°C to 80°C, the drying time is 12 to 24 hours, and the dried lignite is crushed and ground.

The second step is further specifically mixing the lignite powder screened in the first step with the iron-based activator, adding deionized water, and stirring to make it fully mixed.

Wherein, the mass ratio of lignite pulverized coal to iron-based activator is 1:(0.2-3).

Wherein, the iron-based activator is one or a mixture of two or more of iron-based compounds such as iron salts and iron oxides.

Wherein, the third step further specifically includes placing the mixture obtained after stirring in the second step in a blast drying oven to dry for 12-24 hours at a drying temperature of 100°C to 120°C, and then grinding after drying.

Wherein, the fourth step is further specifically adding the powdery mixture obtained in the third step into the pyrolysis reactor for high temperature pyrolysis, and the pyrolysis temperature is a heating rate of 2 to 10°C/min, and the temperature is 700 ~ 1000 ℃, and constant temperature reaction 0.5 ~ 5h.

Wherein, the fifth step is further specifically to put the pyrolysis product obtained in the fourth step into an oven for drying treatment, and after drying, magnetic activated carbon is obtained.

The present invention also provides a method for treating wastewater containing heavy metal ions, comprising:

The magnetic activated carbon provided by the present invention is put into waste water, shaken at a constant temperature for 0.5 to 12 hours at a temperature of 15° C. to 40° C., left for a period of time, and filtered.

Wherein, the heavy metal ions include one or more of lead, iron, cobalt, copper, nickel, chromium, and cadmium.

The beneficial effects of the present invention

(1) the present invention adopts lignite as the main raw material, so that the cost of the raw material is greatly reduced, the preparation process is simple, the manufacturing cost of the adsorbent is saved, and the high value-added utilization of the lignite is realized;

(2) The adsorbent prepared by the present invention can adsorb lead, iron, cobalt, copper, nickel, chromium, cadmium plasma, and the adsorption effect is obvious;

(3) the preparation process of the magnetic activated carbon in the present invention is simple, the adsorption effect is obvious, the cost is low, the application scope of the magnetic adsorption material is broadened, and the magnetic adsorption material has a wide application prospect;

(4) The maximum adsorption capacity of the magnetic activated carbon in the present invention to lead ions can reach 1219.26 mg/L, which is better than the adsorption effect of conventional adsorbents.

Description of drawings

Fig. 1 is the nitrogen adsorption test of the magnetic activated carbon synthesized by the method of Example 1 of the present invention.

FIG. 2 is an infrared spectrum diagram of the magnetic activated carbon synthesized by the method of Example 1 of the present invention.

3 is the adsorption test curve of the magnetic activated carbon synthesized by the method of Example 1 of the present invention to the lead ion solutions with different initial concentrations.

Detailed ways

The invention provides a preparation method of lignite-based magnetic activated carbon, which comprises:

The first step, lignite pretreatment, to obtain lignite pulverized coal;

The second step, impregnation mixing, mixing lignite powder and iron-based activator;

The third step is drying and grinding;

The fourth step, high temperature pyrolysis;

The fifth step is drying.

The first step is further specifically to put the lignite into an oven for drying treatment, the drying temperature is 60°C to 80°C, the drying time is 12 to 24 hours, the dried lignite is crushed and ground, and sieved to obtain 50 to 200 mesh. Lignite powder.

The second step is further specifically: mixing the lignite powder screened in the first step with the iron-based activator, adding deionized water, stirring for 12 to 24 hours to make it fully mixed, and the quality of the lignite powder and the iron-based activator. The ratio is 1:(0.2-3), and the iron-based activator can be one or a mixture of two or more of iron-based compounds such as iron salts and iron oxides.

The third step is further specifically: placing the mixture obtained after stirring in the second step in a blast drying oven for 12 to 24 hours, drying at a temperature of 100° C. to 120° C. After drying, grinding is performed to obtain a powdery product. Mixture.

The fourth step is further specifically adding the powdery mixture obtained in the third step into the pyrolysis reactor for high-temperature pyrolysis, and the pyrolysis temperature is a heating rate of 2 to 10° C./min, and the temperature is increased to 700 to 700°C. 1000 ℃, and constant temperature reaction 0.5 ~ 5h, after the pyrolysis reactor is cooled to room temperature, the pyrolysis product is taken out.

The fifth step is further specifically to put the pyrolysis product obtained in the fourth step into an oven for drying treatment, and after drying, magnetic activated carbon is obtained.

The present invention also provides a method for treating wastewater containing heavy metal ions, comprising:

The magnetic activated carbon provided by the present invention is put into waste water, shaken at a constant temperature for 0.5 to 12 hours at a temperature of 15° C. to 40° C., left for a period of time, and filtered.

The heavy metal ions include one or more of lead, iron, cobalt, copper, nickel, chromium, and cadmium.

Using the lignite-based magnetic activated carbon prepared by the method of the present invention as an adsorbent, an adsorption test is carried out on a solution containing heavy metal ions such as lead, iron, cobalt, copper, nickel, chromium, cadmium, etc. It is prepared by the lignite-based magnetic activated carbon preparation method described in ~5. The prepared lignite-based magnetic activated carbon showed better adsorption performance than conventional adsorbents, especially the adsorption capacity of heavy metal lead ions reached 1219.26 mg/L, and the removal rates of lead, iron, cobalt, copper, nickel, chromium and cadmium ions were all in the more than 98%.

Embodiments of the present invention are described in detail below by using examples and drawings, so as to fully understand and implement the implementation process of how to apply technical means to solve technical problems and achieve technical effects in the present invention.

Example 1

In this embodiment, a preparation method for synthesizing magnetic activated carbon with excellent heavy metal ion adsorption performance by using lignite as raw material and utilizing chemical activation means is as follows: using lignite and iron-based activator as raw materials, drying, immersing and steaming After drying, pyrolysis and other technological processes, magnetic activated carbon is obtained. The preparation method comprises the following steps:

Put the lignite in an oven at 80°C for drying treatment for 24h, crush, grind and sieve the dried lignite to obtain 200 mesh lignite powder; weigh 10g lignite powder (200 mesh) and 15g ferric chloride and ferric acid respectively. The potassium mixture was mixed, and deionized water was added for stirring. The ratio of the volume of the added deionized water to the mass of the solid mixture was 2:1. After the stirring, the mixture was placed in an oven at 120 ° C to dry for 12 hours, and the dried mixture was The material was transferred to the pyrolysis reactor, heated to 1000°C at a rate of 10°C/min for a constant temperature reaction for 3 hours, cooled to room temperature after the pyrolysis was completed, and the pyrolysis product was taken out and placed in an 80°C oven for drying treatment for 12 hours. , the lignite-based magnetic activated carbon can be obtained.

Example 2

Put the lignite in an oven at 80°C for drying treatment for 24 hours, crush, grind and sieve the dried lignite to obtain 200 mesh lignite pulverized coal; weigh 10 g of lignite pulverized coal (200 mesh), add deionized water for stirring, The ratio of the volume of the deionized water added to the mass of the solid mixture was 2:1. The mixture after stirring was placed in an oven at 100 °C for drying for 12 hours, and the dried mixture was transferred to the pyrolysis reactor. The temperature was raised to 1000 °C for 3 h at a constant temperature of 1 min. After the pyrolysis was completed, it was naturally cooled to room temperature. The pyrolysis product was taken out and placed in an oven at 80 °C for drying treatment for 12 h. After drying, lignite-based magnetic activated carbon was obtained.

Example 3

Put the lignite in an oven at 80°C for drying treatment for 24h, crush, grind and sieve the dried lignite to obtain 200 mesh lignite powder; respectively weigh 10g lignite powder (200 mesh) and mix with 2.5g ferric chloride, And add deionized water for stirring, the ratio of the volume of the added deionized water to the mass of the solid mixture is 2:1, put the stirred mixture into a 120 °C oven for 24 hours, and transfer the dried mixture to pyrolysis In the reactor, the temperature was raised at a rate of 10°C/min to 1000°C for a constant temperature reaction for 3h, and after the pyrolysis was completed, it was naturally cooled to room temperature, and the pyrolysis product was taken out and placed in an 80°C oven for drying for 12 hours. After drying, lignite was obtained. based magnetic activated carbon.

Example 4

The magnetic activated carbon prepared by the above-mentioned specific embodiments 1-2 in the present invention is subjected to a heavy metal ion adsorption performance test:

Prepare a solution of Pb ²⁺ , Fe ³⁺ , Co ²⁺ , Cu ²⁺ , Cr ³⁺ , Ni ²⁺ , Cd ²⁺ with a mass concentration of 100mg/L, the pH of the solution is calibrated to 5, and 10ml of each solution is taken Then add 10 mg of the magnetic activated carbon prepared in the present invention respectively, shake at a constant temperature of 25°C for 12 hours, let stand for a period of time, then filter, and take the filtrate to measure the change of each ion concentration in the solution before and after adsorption. The amount of adsorption obtained is shown in Table 1.

Table 1 Adsorption properties of magnetic activated carbon for different heavy metal ions

Adsorption capacity (mg/l) Pb²⁺ Fe³⁺ Co²⁺ Cu²⁺ Cr³⁺ Ni²⁺ Cd²⁺ Example 1 146.99 116.7 142.7 90.98 125.5 123.4 122.96 Example 2 115.05 14.11 39.44 23.16 7.51 32.64 23.79

As can be seen from Table 1, the adsorption effect of the activated carbon prepared under the condition of not adding the iron-based activator in Example 2 is worse than that of Example 1. With the addition of the iron-based activator, the prepared magnetic activated carbon has no effect on various heavy metal ions. The adsorption effect was significantly increased.

Fig. 1 is the nitrogen adsorption test result of the magnetic activated carbon synthesized by the method of Example 1 of the present invention; Fig. 2 is the infrared spectrum of the magnetic activated carbon synthesized by the method of Embodiment 1 of the present invention; Fig. 3 is Embodiment 1 of the present invention The adsorption test of the magnetic activated carbon synthesized by the method of different initial concentrations of lead ion solution.

All of the above-mentioned primary implementations of this intellectual property do not set limits to other forms of implementation of this new product and/or new method. Those skilled in the art will use this important information to modify the above to achieve a similar implementation. However, all modifications or alterations to new products based on the present invention are reserved.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications to equivalent changes. Example. However, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention still belong to the protection scope of the technical solutions of the present invention.

Claims (10)

1. a preparation method of lignite-based magnetic activated carbon, is characterized in that, comprises: The first step, lignite pretreatment, to obtain lignite pulverized coal; The second step, impregnation mixing, mixing lignite powder and iron-based activator; The third step is drying and grinding; The fourth step, high temperature pyrolysis; The fifth step is drying. 2. the preparation method of the lignite-based magnetic activated carbon as claimed in claim 1, it is characterized in that: the described first step is further specifically to put the lignite into an oven for drying, the drying temperature is 60 ℃～80 ℃, and the drying time is 12 ~24h, the dried lignite is crushed and ground. 3. the preparation method of the lignite-based magnetic activated carbon as claimed in claim 1 or 2, it is characterized in that: described second step is further specifically to mix the lignite-based activator and iron-based activator screened in the first step, add deionization water, and stir to mix well. 4. The preparation method of lignite-based magnetic activated carbon according to claim 1 or 2, characterized in that: the mass ratio of lignite-based pulverized coal to iron-based activator is 1:(0.2～3). 5. the preparation method of lignite-based magnetic activated carbon as claimed in claim 1 or 2, is characterized in that: described iron-based activator is one or two or more of iron-based compounds such as iron salts, iron oxides, etc. mixture. 6. the preparation method of the described lignite-based magnetic activated carbon as claimed in claim 1 or 2, it is characterized in that: described 3rd step is further specifically that the mixture obtained after the second step is stirred is placed in a blast drying oven for drying 12 ～24h, drying temperature is 100℃～120℃, and then grinded after drying. 7. the preparation method of lignite-based magnetic activated carbon as claimed in claim 1 or 2, it is characterized in that: the described 4th step is further specifically for adding the powdery mixture that the 3rd step obtains in the pyrolysis reactor to carry out high temperature Pyrolysis, the pyrolysis temperature is 2-10 ℃/min heating rate, heating to 700-1000 ℃, and constant temperature reaction 0.5-5h. 8. the preparation method of lignite-based magnetic activated carbon as claimed in claim 1 or 2, it is characterized in that: described 5th step is further concretely to put the pyrolysis product obtained in 4th step into drying oven and carry out drying process, after drying, obtain Magnetic activated carbon. 9. A method for treating wastewater containing heavy metal ions, comprising: The magnetic activated carbon prepared by the preparation method of any one of claims 1 to 8 is put into waste water, shaken at a constant temperature for 0.5 to 12 hours at a temperature of 15° C. to 40° C., stand for a period of time, and filter. 10 . The method for treating wastewater containing heavy metal ions according to claim 9 , wherein the heavy metal ions comprise one or more of lead, iron, cobalt, copper, nickel, chromium, and cadmium. 11 .

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