CN117756202A

CN117756202A - Fluorine removing agent, preparation method and application thereof and fluorine removing device

Info

Publication number: CN117756202A
Application number: CN202311830488.6A
Authority: CN
Inventors: 汪冬冬; 董锦云; 朱少波; 初晓冶; 徐磊; 陆豪; 汪昱昆; 胡海畅; 张岩
Original assignee: Shanghai Investigation Design and Research Institute Co Ltd SIDRI
Current assignee: Shanghai Investigation Design and Research Institute Co Ltd SIDRI
Priority date: 2023-12-28
Filing date: 2023-12-28
Publication date: 2024-03-26

Abstract

The invention belongs to the field of sewage and wastewater treatment, and particularly relates to a fluorine removing agent, a preparation method and application thereof, and a fluorine removing device. The defluorinating agent consists of biochar 3-5 weight portions; 3-5 parts of cast iron powder; 6-12 parts of modified attapulgite. The defluorinating agent has the advantages of low price of the selected raw materials, easy acquisition, environment friendliness, no harm and easy post-treatment. Compared with other defluorinating agents, the preparation process is simple and easy to realize.

Description

Fluorine removing agent, preparation method and application thereof and fluorine removing device

Technical Field

The invention belongs to the field of sewage and wastewater treatment, and particularly relates to a fluorine removing agent, a preparation method and application thereof, and a fluorine removing device.

Background

Fluorine is one of the most common elements in nature, and has obvious biotoxicity. The fluorine element in the water body is over-standard, which not only can influence the survival of aquatic organisms and destroy ecological balance, but also can seriously harm human health, such as caries, decrease bone structure and strength, destroy nervous system and immune system, etc. The emission of fluorine-containing industrial wastewater is an important cause of exceeding the standard of fluorine element in natural water. In recent decades, as the industries of metallurgy, semiconductors, pharmacy, chemical industry, materials and the like rapidly develop, the discharge amount of fluorine-containing wastewater is increased, and the problem of fluorine pollution of water bodies is frequent. Thus, there is a need to enhance the treatment of fluorine-containing wastewater.

The defluorination agent is a main fluorine-containing wastewater treatment method, and has the characteristics of high efficiency, simplicity in operation, low cost and the like, and has a wide application prospect. The current commonly used fluorine removing agents comprise various calcium salts, aluminum salts and magnesium salts, and composite agents prepared by mixing the salts and auxiliary materials, and most of fluorine ions are removed by utilizing the principle of chemical precipitation, namely insoluble fluoride is generated by the fluorine ions in water, and then precipitation is removed. These fluorine scavengers are large in amount and high in price, and have a good treatment effect only on high-concentration fluorine-containing wastewater (fluoride ion concentration of several tens to several hundreds milligrams per liter), but often have an unsatisfactory treatment effect on low-concentration fluorine-containing wastewater (fluoride ion concentration of several tens to several milligrams per liter). In particular, when a certain amount of organic matters are contained in the fluorine-containing wastewater, the organic matters are combined with the fluorine removing agent, so that the treatment effect on the low-concentration fluorine-containing wastewater is remarkably reduced. In view of the above, there is a need for development of a fluorine-removing agent which is low in cost and has a good treatment effect on fluorine-containing wastewater containing a certain organic matter at a low concentration.

Disclosure of Invention

In view of the technical problems that the fluorine removing agent in the prior art is large in dosage, high in price, low in fluorine content and contains a certain organic matter, the invention provides a fluorine removing agent, a preparation method and application thereof and a fluorine removing device.

To achieve the above and other related objects, a first aspect of the present invention provides a fluorine scavenger comprising, in parts by weight

3-5 parts of biochar;

3-5 parts of cast iron powder;

6-12 parts of modified attapulgite.

Preferably, A1) further comprises 5 to 10 parts of one or more of polyaluminum chloride, polyaluminum sulphate or polyaluminum sulphide chloride.

Preferably, A2) also comprises 5-10 parts of one or more of polymeric ferric chloride or polymeric ferric sulfate, the polymeric aluminum chloride and the polymeric ferric chloride remove fluorine through chemical precipitation, the auxiliary fluorine removal effect is realized, the quantity is excessive, and for low-concentration fluorine wastewater containing organic matters, the fluorine removal effect is not good, and raw materials are wasted.

Preferably, A3) further comprises 1 to 4 parts of one or more of citric acid or oxalic acid.

The modified attapulgite has excellent adsorption performance, can remove fluorine ions through adsorption, can slowly release polyaluminium chloride and polyferric chloride combined in the fluorine removing agent, can generate tiny insoluble precipitate through the fluorine ions, and is adsorbed on the surface of the modified attapulgite, so that the effect of removing the fluorine ions is enhanced; the biochar and the cast iron powder form an iron-carbon primary battery, and the organic matters are oxidized through micro-electrolysis and electrolysis to play a role in removing the organic matters, and meanwhile, the process of removing fluorine ions by the adsorption and chemical precipitation by the organic matters is avoided; on one hand, the citric acid is used as a complexing agent to promote the organic combination of the components, and meanwhile, the acid leaching can be used for activating the surface groups of the material, so that the defluorination effect of the components is improved as a whole.

The components in the invention are important factors for determining the defluorination effect, and the modified attapulgite is defluorinated by the adsorption principle, so that the defluorination effect is poor due to too small quantity; excessive amount affects fluorine and simultaneously adsorbs a large amount of organic matters; the adsorbed large amount of organic matters are covered on the surface of the defluorinating agent, so that the effect of strengthening defluorination of polyaluminium chloride and polyferric chloride through chemical precipitation can be affected; biochar and cast iron powder function: forming an iron-carbon primary cell, removing organic matters through iron-carbon micro-electrolysis, wherein the quantity of the organic matters is too small to achieve the effect; excessive amounts are detrimental to the defluorination of the defluorinating agent.

The invention provides a preparation method of a fluorine removing agent, which comprises the steps of weighing raw materials according to a formula, carrying out first mixing on modified attapulgite and deionized water, then carrying out second mixing on the modified attapulgite, biochar and cast iron powder, and drying to obtain the fluorine removing agent.

Preferably, the mass ratio of the modified attapulgite to the deionized water is (2-4): 1.

preferably, B2) when said second mixing is performed, further comprising adding one or more of polyaluminum chloride, polyaluminum sulfate or polyaluminum sulfate chloride;

preferably, B3) when said second mixing is performed, further comprising adding one or more of polymeric ferric chloride or polymeric ferric sulfate;

preferably, B4) when said second mixing is performed, a first stirring is performed;

preferably, the temperature of the drying of B5) is 40-80 ℃;

preferably, B6) said drying further comprises granulating and drying in the shade;

preferably, the preparation method of the biochar of B7) comprises the following steps: drying and crushing straw, and calcining under nitrogen environment to obtain the biochar;

preferably, the preparation method of the modified attapulgite of the B8) comprises the following steps: and (3) reacting the attapulgite with an aqueous solution of sodium hydroxide, and performing first cleaning to obtain the modified attapulgite.

Preferably, in the B41) feature B4), the first stirring further comprises adding one or more of citric acid or oxalic acid;

preferably, in the B61) feature B6), the particle size of the granulation is 1 to 3mm; for example, it may be 1 to 2mm, 2 to 3mm, or the like.

Preferably, in the B71) feature B7), the straw is selected from one or more of rice, wheat, or corn straw.

Preferably, in the B72) feature B7), the straw is subjected to a second wash prior to drying.

Preferably, in the B73) feature B7), the comminution is to a diameter of 1 to 3cm; for example, it may be 1 to 2cm, 2 to 3cm, or the like.

Preferably, in B74) feature B7), the calcination time is 1 to 6 hours; for example, it may be 1 to 2 hours, 2 to 63 hours, 3 to 4 hours, 4 to 5 hours, 5 to 6 hours, etc.

Preferably, in the B75) feature B7), the calcination temperature may be 450 to 550 ℃, for example, 450 to 460 ℃, 460 to 470 ℃, 470 to 480 ℃, 480 to 490 ℃, 490 to 500 ℃, 500 to 510 ℃, 510 to 520 ℃, 520 to 530 ℃, 530 to 540 ℃, 540 to 550 ℃, and the like.

Preferably, in the B76) feature B7), the speed of the calcination is 5 to 10 ℃/min, and may be, for example, 5 to 6 ℃/min, 6 to 7 ℃/min, 7 to 8 ℃/min, 8 to 9 ℃/min, 9 to 10 ℃/min, or the like.

Preferably, in B81) feature B8), the attapulgite is 1: (2-5).

Preferably, in the B82) feature B8), the concentration of the sodium hydroxide is 0.5 to 2mol/L, for example, 0.5 to 0.7mol/L, 0.7 to 0.9mol/L, 0.9 to 1.1mol/L, 1.1 to 1.3mol/L, 1.3 to 1.5mol/L, 1.5 to 1.7mol/L, 1.7 to 2mol/L, and the like.

Preferably, in the B83) feature B8), the reaction time is 2 to 6 hours, and may be, for example, 2 to 3 hours, 3 to 4 hours, 4 to 5 hours, 5 to 6 hours, or the like.

Preferably, in B82) feature B8), a third stirring is performed during said mixing.

Preferably, in B83) feature B8), the first cleaning reagent is deionized water.

Preferably, in B84) feature B8), the first wash is to neutral.

The third aspect of the invention provides an application of the fluorine removing agent, wherein the fluorine removing agent is applied to wastewater containing fluorine and organic matters. Is especially suitable for fluorine-containing wastewater with low concentration (fluoride ion concentration of several milligrams to tens of milligrams per liter) and a certain amount of organic matters.

The fourth aspect of the invention provides a fluorine removal device, wherein the fluorine removal agent is put into the fluorine removal device to remove fluorine, the fluorine removal device comprises a water quality adjusting tank and a fluorine removal reaction tank, and the water quality adjusting tank is communicated with the fluorine removal reaction tank through a pipeline.

Preferably, the water quality regulating tank is provided with a water inlet pipe, and the water inlet pipe is communicated with the water quality regulating tank.

Preferably, C2) an aeration disc is arranged in the water quality regulating tank.

Preferably, a stirring piece is arranged in the defluorination reaction tank C3).

Preferably, the C4) is provided with a water outlet pipe, and the water outlet pipe is communicated with the defluorination reaction tank.

Preferably, C5) the defluorination device further comprises a water return pipe, one end of the water return pipe is communicated with the water quality adjusting tank, and the other end of the water return pipe is communicated with the defluorination reaction tank.

Preferably, C6) the fluorine removal device further comprises a pH adjusting liquid reservoir in line communication with the water quality adjusting reservoir.

Preferably, in C11) feature C1), the water inlet pipe penetrates through the water quality adjusting tank, and a water distribution port is arranged at one end of the water inlet pipe located in the water quality adjusting tank=.

Preferably, in C51) feature C5), a return pump is provided on the return pipe.

Preferably, in the C52) feature C5), a filter screen is disposed at the opening of the water return pipe near the defluorination reaction tank.

Preferably, in the C61) feature C6), a metering pump is provided on a line connecting the pH adjusting liquid reservoir and the water quality adjusting tank.

According to the invention, the pH of the fluorine-containing wastewater is regulated to be weak acid by the water tank regulating tank in the fluorine removal device, and the fluorine-containing wastewater is oxygenated by aeration, so that the subsequent micro-electrolysis of iron and carbon is facilitated to degrade organic matters; meanwhile, the weak acid water quality condition is also favorable for removing fluoride ions from polyaluminum chloride and ferric chloride through chemical precipitation; and adding a fluorine removing agent into the fluorine removing reaction tank, fully contacting fluorine-containing wastewater through stirring, and setting a reflux process to furthest play the fluorine removing effect of the fluorine removing agent.

In a fifth aspect, the present invention provides a method for removing fluorine, which comprises injecting fluorine-containing wastewater into the water quality adjusting tank to adjust pH, and then injecting into the fluorine removal reaction tank to remove fluorine, using the fluorine removing agent and the fluorine removing device.

Preferably, D1) adjusting the pH to 6 to 7;

preferably, the mass-volume ratio of the defluorinating agent to the fluorine-containing wastewater of D2) is 0.1 to 0.4, and may be, for example, 0.1 to 0.2, 0.2 to 0.3, 0.3 to 0.4, etc.

Preferably, the volume ratio of the water amount discharged by the water outlet pipe to the circulating water return pipe is 1: (2-4).

The invention has at least one of the following technical effects:

1) The defluorinating agent has the advantages of low price of the selected raw materials, easy acquisition, environment friendliness, no harm and easy post-treatment.

2) Compared with other defluorinating agents, the preparation process is simple and easy to realize.

3) The invention comprehensively considers the characteristics of different materials, organically combines the materials, has excellent treatment effect on low-concentration fluorine-containing wastewater, and simultaneously is coupled with the technology of 'iron-carbon micro electrolysis', so that the fluorine removal agent can degrade organic matters and can enhance the treatment effect on the low-concentration fluorine-containing wastewater containing the organic matters.

4) According to the characteristic of the composite defluorinating agent, the invention also provides a matched application device, which is convenient for the practical application of the defluorinating agent and can further enhance the defluorinating efficiency.

Drawings

FIG. 1 is a graph showing the effect of example 3 of the present invention on fluoride ion removal from wastewater containing fluorine.

FIG. 2 is a schematic view of a fluorine removal device according to the present invention.

FIG. 3 shows the effect of the defluorinating agent in combination with the defluorinating apparatus in the embodiment 3 of the present invention on the removal of fluoride ions in wastewater containing fluorine.

Reference numerals:

1. water quality regulating tank

2. Defluorination reaction tank

3. Water inlet pipe

4. Aeration disc

5. Stirring piece

6. Water outlet pipe

7. Water return pipe

8 pH regulating fluid reservoir

9. Water distribution port

10. Reflux pump

11. Filter screen

12. Metering pump

Detailed Description

Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.

Where numerical ranges are provided in the examples, it is understood that unless otherwise stated herein, both endpoints of each numerical range and any number between the two endpoints are significant both in the numerical range. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In addition to the specific methods, devices, materials used in the embodiments, any methods, devices, and materials of the prior art similar or equivalent to those described in the embodiments of the present invention may be used to practice the present invention as would be apparent to one of skill in the art having possession of the prior art and having possession of the present invention.

Example 1

A preparation method of a defluorinating agent comprises the following steps: mixing 6 parts of modified attapulgite with 3 parts of deionized water, sequentially adding 3 parts of biochar, 3 parts of cast iron powder, 5 parts of polyaluminum chloride and 5 parts of polyferric chloride, stirring on a stirrer, and fully mixing to obtain a mixture A; adding 1 part of citric acid, and stirring in a water bath at 20 ℃ to obtain a mixture B; after stirring, placing the mixture B in an electrothermal blowing drying oven, and drying at 60 ℃ to obtain a solid C; and (3) placing the solid C into a granulator to prepare particles with the diameter of 1-3 mm, and drying in the shade at a ventilated and dried place to obtain the fluorine removing agent.

The preparation method of the biochar comprises the following steps: collecting rice straw, cleaning the rice straw by using deionized water, and drying the rice straw in an electrothermal blowing drying oven; crushing the pretreated crop straws into chips with the diameter of about 1cm, placing the chips in a tube furnace, calcining for 2 hours at the temperature of 450 ℃ under the nitrogen atmosphere, and heating at the speed of 5 ℃/min; and after the calcination is finished, collecting black powder, namely the biochar.

The preparation method of the modified attapulgite comprises the following steps: and (3) obtaining attapulgite, mixing the attapulgite with 0.5mol/L sodium hydroxide, stirring and reacting for 2 hours, and cleaning the attapulgite with deionized water until the attapulgite is neutral after the reaction is finished, thus obtaining the modified attapulgite.

The treatment effect of example 1 above on fluorine-containing wastewater was examined by the beaker test. Waste water was taken from a certain plant and used as test raw water. The method adopts a fluoride ion selective electrode method to measure the fluoride ion content in raw water, the measurement principle is that the fluoride ion selective electrode and a saturated calomel electrode are used as reference electrodes, the measurement is carried out by a direct potential method, and the type of the fluoride ion electrode is Shanghai Lei Ci PXSJ-216F. The chemical oxygen demand of the raw water is measured by adopting national standard GB11914-89 of the people's republic of China, so as to measure the organic matter content in the water body. The content of fluoride ions in raw water is 14.6mg/L and the content of COD is 158.6mg/L.

500ml of the test raw water was taken in a 1L beaker, the fluorine-removing agent obtained in example 1 was added in amounts of 1,2,4,6,8, 10g/L, respectively, and reacted for 2 hours under the condition of 300rpm on a magnetic stirrer, and after the reaction was completed, the fluorine-removing agent in the test raw water was centrifugally removed, and the residual fluorine ion concentration was measured by a fluorine ion selective electrode method, and the fluorine ion removal rate was calculated by subtracting the residual fluorine ion concentration from the initial fluorine ion concentration and dividing by the initial fluorine ion concentration.

Example 2

A preparation method of a composite defluorinating agent comprises the following steps: mixing 10 parts of modified attapulgite with 5 parts of deionized water, sequentially adding 5 parts of biochar, 5 parts of cast iron powder, 8 parts of polyaluminum chloride and 8 parts of polyferric chloride, stirring on a stirrer, and fully mixing to obtain a mixture A; adding 2 parts of oxalic acid, and stirring in a water area at 20 ℃ to obtain a mixture B; after stirring, placing the mixture B in an electrothermal blowing drying oven, and drying at 60 ℃ to obtain a solid C; and (3) placing the solid C into a granulator to prepare particles with the diameter of 1-3 mm, and drying in the shade at a ventilated and dried place to obtain the fluorine removing agent.

The preparation method of the biochar comprises the following steps: collecting rice straw, cleaning the rice straw by using deionized water, and drying the rice straw in an electrothermal blowing drying oven; crushing the pretreated crop straws into chips with the diameter of about 1cm, placing the chips in a tube furnace, calcining for 2 hours at 550 ℃ under the nitrogen atmosphere, and heating at a speed of 5 ℃/min; and after the calcination is finished, collecting black powder, namely the biochar.

The preparation method of the modified attapulgite comprises the following steps: and (3) obtaining attapulgite, mixing the attapulgite with 1mol/L sodium hydroxide, stirring and reacting for 6 hours, and cleaning the attapulgite with deionized water until the attapulgite is neutral, thus obtaining the modified attapulgite.

The resulting fluorine scavenger was tested by the method of example 1.

Comparative example 1

The effect of defluorination of polyaluminium chloride was tested under the same conditions as in example 1, specifically, 500ml of test raw water was taken in a 1L beaker, polyaluminium chloride was added in the same amounts of 1,2,4,6,8, 10g/L, and reacted for 2 hours under the condition of 300rpm on a magnetic stirrer.

Comparative example 2

A preparation method of a composite defluorinating agent comprises the following steps: mixing 10 parts of modified kaolin with 5 parts of deionized water, sequentially adding 5 parts of biochar, 5 parts of cast iron powder, 8 parts of polyaluminum chloride and 8 parts of polyferric chloride, stirring on a stirrer, and fully mixing to obtain a mixture A; adding 2 parts of citric acid, and stirring in a water area at 20 ℃ to obtain a mixture B; after stirring, placing the mixture B in an electrothermal blowing drying oven, and drying at 60 ℃ to obtain a solid C; and (3) placing the solid C into a granulator to prepare particles with the diameter of 1-3 mm, and drying in the shade at a ventilated and dried place to obtain the fluorine removing agent.

The preparation method of the modified kaolin comprises the following steps: and (3) obtaining kaolin, mixing the kaolin with 1mol/L sodium hydroxide, stirring and reacting for 6 hours, and cleaning the kaolin to be neutral by using deionized water after the reaction is finished, thus obtaining the modified attapulgite.

The resulting fluorine scavenger was tested by the method of example 1.

As shown in figure 1, the composite fluorine removing agent has the effect of removing fluoride ions in fluorine-containing wastewater. As can be seen from fig. 1, the fluorine removal effect of the fluorine removal agents prepared in examples 1 and 2 was rapidly increased as the addition amount was increased. When the adding amount is only 1-2 g/L, the concentration of the fluoride ions can be lower than 10mg/L, thereby meeting the requirement of the wastewater comprehensive discharge Standard (GB 8978-1996) that the concentration of the fluoride ions in the primary standard should be lower than 10 mg/L; the polyaluminium chloride is added to meet the requirement, and the dosage is 2-4 g/L. Along with the addition amount reaching 10g/L, the concentration of the fluoride ions can be lower than 1.5mg/L, and the limit standard of the latest revised edition on the concentration of the fluoride in the pollutant emission standard of urban sewage treatment plants (GB 18918-2002) is met. However, the conventional fluorine removing agent (polyaluminum chloride, comparative example 1) has lower effect on removing fluorine ions than the compound fluorine removing agent (fig. 1) at the corresponding addition amount, and the residual fluorine ion concentration is 4.8mg/L, which is far higher than the emission requirement of 1.5mg/L at the same addition amount of 10 g/L.

FIG. 1 also shows the fluoride ion removal effect of comparative example 2 on the fluoride containing wastewater. Comparative example 2 differs from examples 1 and 2 in that kaolin was used instead of attapulgite. As can be seen from FIG. 1, the effect of comparative example 1 on removal of fluoride ions was lower than that of examples 1 and 2 in which attapulgite was the main component, and also lower than that of polyaluminum chloride.

Example 3

On the basis of the beaker test example 3, the defluorinating agent prepared in the example 1 is combined with a defluorinating device, the defluorinating effect is explored, and the specific application situation is further described below:

as shown in fig. 2, a schematic diagram of a defluorinating agent application device is shown, the defluorinating device comprises a water quality regulating tank 1 and a defluorinating reaction tank 2, the water quality regulating tank 1 and the defluorinating reaction tank 2 are communicated through the pipeline, a water inlet pipe 3 is arranged on the water quality regulating tank 1, the water inlet pipe 3 penetrates through the water quality regulating tank 1, a water distribution port 9 is arranged at one end of the water inlet pipe 3, which is positioned at the water quality regulating tank 1, and an aeration disc 4 is arranged in the water quality regulating tank 1; the water inlet pipe 3 is communicated with the water quality regulating tank 1; the fluorine removal reaction tank 2 is internally provided with a stirring piece 5, the stirring piece 5 is a stirrer 8, the fluorine removal reaction tank 2 is provided with a water outlet pipe 6, the water outlet pipe 6 is communicated with the fluorine removal reaction tank 2, the fluorine removal device further comprises a water return pipe 7, one end of the water return pipe 7 is communicated with the water quality regulating tank 1, the other end of the water return pipe 7 is communicated with the fluorine removal reaction tank 2, a reflux pump 10 is arranged on the water return pipe 7, the water return pipe 7 is close to the opening of the fluorine removal reaction tank 2 is provided with a filter screen 11, the fluorine removal device further comprises a pH regulating solution reserve tank 8, the pH regulating solution reserve tank 8 is communicated with the water quality regulating tank 1 through a pipeline, and a metering pump 12 is arranged on a pipeline of the pH regulating solution reserve tank 8 and the water quality regulating tank 1.

The method for removing fluorine by adopting the fluorine removing device comprises the steps that fluorine-containing wastewater firstly enters a water quality regulating tank 1 from a water inlet pipe 3, meanwhile, air is supplied to an aeration disc 4 for oxygenation, pH regulating liquid in a pH regulating liquid storage tank 8 is sucked into the water quality regulating tank 1 by a metering pump 12, and the pH of the pH regulating liquid is regulated to 6.5; then, the fluorine-containing wastewater subjected to water quality adjustment enters a fluorine-removing reaction tank 2 through a pipeline, the fluorine-removing reaction tank 2 is filled with the fluorine-removing agent in the embodiment 1, the filling amount of the fluorine-removing agent is 0.1 of the volume of the fluorine-containing wastewater, and the stirring machine 8 is fully stirred to enable the fluorine-removing agent to suspend and fully contact with the fluorine-containing wastewater; then, part of the fluorine-containing wastewater flows out of the defluorination reaction tank 9, and the other part flows back to the water quality regulating tank 1 through the water return pipe 7, and the volume ratio is 1:2, namely the ratio of the volume of the water discharged from the defluorination reaction tank 2 to the volume of the water flowing back to the water quality regulating tank 1 is 1:2.

FIG. 3 shows the effect of the composite defluorinating agent on removing fluoride ions in wastewater containing fluoride when the composite defluorinating agent is combined with an application device of the composite defluorinating agent. As can be seen from the graph, the fluorine removal effect is relatively unstable in the initial operation period (within 5 h), but after 5h, the fluorine removal rate can be stabilized to be about 92-94%, which is higher than the removal rate of about 90% in a beaker test, so that the fluorine removal effect of the fluorine removal agent can be further improved by combining the fluorine removal agent with the modified device.

The above examples are provided to illustrate the disclosed embodiments of the invention and are not to be construed as limiting the invention. In addition, many modifications and variations of the methods and compositions of the invention set forth herein will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. While the invention has been specifically described in connection with various specific preferred embodiments thereof, it should be understood that the invention should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the present invention.

Claims

1. A defluorinating agent is characterized by comprising the following components in parts by weight

3-5 parts of biochar;

3-5 parts of cast iron powder;

6-12 parts of modified attapulgite.

2. The fluorine removal agent of claim 1, comprising at least one of the following technical characteristics:

a1 5-10 parts of one or more of polyaluminum chloride, polyaluminum sulfate or polyaluminum sulfate chloride;

a2 5-10 parts of one or more of polymeric ferric chloride or polymeric ferric sulfate;

a3 And 1 to 4 parts of one or more of citric acid or oxalic acid.

3. The method for preparing the fluorine removing agent according to claim 1 or 2, wherein raw materials are weighed according to a formula, modified attapulgite is first mixed with deionized water, then is second mixed with biochar and cast iron powder, and is dried, so that the fluorine removing agent is obtained.

4. The method for producing a fluorine removing agent according to claim 3, comprising at least one of the following technical features:

b1 The mass ratio of the modified attapulgite to the deionized water is (2-4): 1, a step of;

b2 The second mixing is carried out, and one or more of polyaluminum chloride, polyaluminum sulfate or polyaluminum sulfate chloride are added;

b3 The second mixing further comprises adding one or more of polymeric ferric chloride or polymeric ferric sulfate;

b4 When the second mixing is performed, performing first stirring;

b5 The temperature of the drying is 40-80 ℃;

b6 The drying step further comprises granulating and drying in the shade;

b7 The preparation method of the biochar comprises the following steps: drying and crushing straw, and calcining under nitrogen environment to obtain the biochar;

b8 The preparation method of the modified attapulgite comprises the following steps: and (3) reacting the attapulgite with an aqueous solution of sodium hydroxide, and performing first cleaning to obtain the modified attapulgite.

5. The method for preparing a fluorine removing agent according to claim 4, comprising at least one of the following technical features:

b41 In the step B4), after the first stirring, one or more of citric acid or oxalic acid is added;

b61 In the feature B6), the particle size of the granulation is 1-3 mm;

b71 In the feature B7), the straw is selected from one or more of rice, wheat or corn straw;

b72 In the feature B7), the second cleaning is carried out before the drying of the straw;

b73 In the feature B7), the crushing is carried out until the diameter is 1-3 cm;

b74 In the feature B7), the calcination time is 1 to 6 hours;

b75 In the feature B7), the temperature of the calcination is 450-550 ℃;

b76 In the feature B7), the speed of the calcination is 5-10 ℃/min;

b81 In feature B8), 1 of the attapulgite and the sodium hydroxide: (2-5);

b82 In the feature B8), the concentration of the sodium hydroxide is 0.5-2 mol/L;

b83 In the feature B8), the reaction time is 2-6 h;

b82 In feature B8), a third stirring is performed during the mixing;

b83 In feature B8), the first cleaning reagent is deionized water;

b84 In feature B8), the first wash is to neutral.

6. Use of a fluorine scavenger according to claim 1 or 2 in wastewater containing fluorine and organic matter.

7. A fluorine removal device, characterized in that the fluorine removal agent according to claim 1 or 2 is put into the fluorine removal device for removing fluorine, the fluorine removal device comprises a water quality adjusting tank (1) and a fluorine removal reaction tank (2), and the water quality adjusting tank (1) and the fluorine removal reaction tank (2) are communicated through a pipeline.

8. The fluorine removal device of claim 7, comprising at least one of the following features:

c1 A water inlet pipe (3) is arranged on the water quality regulating tank (1), and the water inlet pipe (3) is communicated with the water quality regulating tank (1);

c2 An aeration disc (4) is arranged in the water quality regulating tank (1);

c3 A stirring piece (5) is arranged in the defluorination reaction tank (2);

c4 A water outlet pipe (6) is arranged on the defluorination reaction tank (2), and the water outlet pipe (6) is communicated with the defluorination reaction tank (2);

c5 The defluorination device further comprises a water return pipe (7), one end of the water return pipe (7) is communicated with the water quality regulating tank (1), and the other end of the water return pipe (7) is communicated with the defluorination reaction tank (2);

c6 The fluorine removal device further comprises a pH regulating solution storage tank (8), and the pH regulating solution storage tank (8) is communicated with the water quality regulating tank (1) through a pipeline.

9. The fluorine removal device of claim 8, comprising at least one of the following features:

c11 In the characteristic C1), the water inlet pipe (3) penetrates through the water quality regulating tank (1), and a water distribution port (9) is arranged at one end of the water inlet pipe (3) positioned in the water quality regulating tank (1);

c51 In the characteristic C5), a reflux pump (10) is arranged on the reflux pipe (7);

c52 In the characteristic C5), a filter screen (11) is arranged at the opening of the water return pipe (7) near the defluorination reaction tank (2);

c61 In the characteristic C6), a metering pump (12) is arranged on a pipeline which is used for communicating the pH regulating liquid storage tank (8) and the water quality regulating tank (1).

10. A method for removing fluorine, characterized in that the fluorine-removing agent according to claim 1 or 2 and the fluorine-removing device according to any one of claims 7 to 9 are adopted, fluorine-containing wastewater is injected into the water quality adjusting tank (1) to adjust the pH, and then is injected into the fluorine-removing reaction tank (2) to remove fluorine.

11. The defluorination method according to claim 10, comprising at least one of the following technical features:

d1 Adjusting the pH to 6-7;

d2 The mass volume ratio of the fluorine removing agent to the fluorine-containing wastewater is 0.1-0.4.