A fluoride ion adsorbent and its preparation method and application

Abstract

The invention discloses a method for preparing a fluoride ion adsorbent: (1) ferric oxide, ferric disulfide and calcium chloride are uniformly mixed to obtain a mixture; wherein the mass ratio of ferric oxide, ferric disulfide and calcium chloride is (10-12): (1-2): (0.08-0.1); (2) the mixture is subjected to one-stage roasting in an atmosphere containing tin tetrafluoride gas to obtain a one-stage roasting slag; (3) the one-stage roasting slag is subjected to two-stage roasting in a water vapor atmosphere to obtain a two-stage roasting slag; (4) the two-stage roasting slag is water-soaked, filtered after the water-soaking is completed, and the fluoride ion adsorbent is obtained. The present invention selects ferric oxide, ferric disulfide and calcium chloride as raw materials, and combines the process control of two-stage roasting, and the adsorbent obtained by water-soaking finally has the characteristics of stable structure, large fluorine adsorption capacity, fast fluorine adsorption rate, etc., and the adsorbent can be separated from the solution without liquid-solid separation.

Description

Technical Field

[0001] The invention relates to the field of adsorbent preparation, and in particular to a fluoride ion adsorbent and a preparation method thereof and application thereof in fluoride-containing wastewater. Background Art

[0002] The discharge of fluoride-containing wastewater will lead to fluoride pollution in local waters, seriously endangering human health and the ecological environment. Adsorption is the most economical and effective method for treating fluoride-containing wastewater, and adsorbent is the key factor affecting fluoride removal efficiency.

[0003] At present, the preparation of defluoridation agents mostly adopts the wet method. For example, the application document with application number 202311198435.7 discloses a cationic covalent organic framework defluoridation adsorbent and its preparation method and application. It uses a phenolic hydroxyl functionalized covalent organic framework COF and a brominated alkylammonium salt compound to carry out a solvent-free grinding reaction at room temperature in the presence of an alkali to prepare a cationic covalent organic framework defluoridation adsorbent PS-COF with an ammonium salt grafted structure. The application document with application number 202211632950.7 discloses a suspended polyhydroxy calcium phosphate defluoridation adsorbent and its preparation method and application. It first prepares calcium hydroxyphosphate, then mixes calcium hydroxyphosphate with a certain amount of dissolved polyvinyl alcohol to react, and vacuum dries to obtain a suspended polyhydroxy calcium phosphate defluoridation adsorbent. The patent application with application number 202211369699.X discloses a defluorination adsorbent, which is poly N,N-(trihydroxysilylureidopropyl)urea. Poly N,N-(trihydroxysilylureidopropyl)urea is a high molecular polymer obtained by deamination condensation-hydrolysis-polycondensation reaction of γ-ureidopropyltriethoxysilane and hydrazine hydrate. At present, these defluorination agents are prepared by wet method, which has the problems of large amount of wastewater generated in the preparation process, complex process, low adsorption capacity, poor stability, etc., and has certain limitations in practical application. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a fluoride ion adsorbent and a preparation method and application thereof.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0006] A method for preparing a fluoride ion adsorbent comprises the following steps:

[0007] (1) mixing ferric oxide, ferric disulfide and calcium chloride uniformly to obtain a mixture; wherein the mass ratio of ferric oxide, ferric disulfide and calcium chloride is (10-12):(1-2):(0.08-0.1);

[0008] (2) calcining the mixture in an atmosphere containing tin tetrafluoride gas to obtain a calcined slag;

[0009] (3) subjecting the first-stage calcined slag to a second-stage calcination in a water vapor atmosphere to obtain a second-stage calcined slag;

[0010] (4) soaking the second-stage calcined slag in water, and filtering it after the soaking to obtain the fluoride ion adsorbent.

[0011] In the above-mentioned method for preparing the fluoride ion adsorbent, preferably, in step (2), the temperature of the first stage calcination is 900-1000° C., and the time of the first stage calcination is 60-90 min.

[0012] In the above-mentioned method for preparing the fluoride ion adsorbent, preferably, in step (2), the atmosphere containing tin tetrafluoride gas is a mixed atmosphere of tin tetrafluoride gas, nitrogen and oxygen.

[0013] In the above-mentioned method for preparing the fluoride ion adsorbent, preferably, in step (2), the mixed atmosphere of tin tetrafluoride gas, nitrogen and oxygen is a mixed gas formed by uniformly mixing nitrogen and oxygen in a volume ratio of 9:1-10:1 and then passing the mixed gas into a tin tetrafluoride gasification device.

[0014] In the above-mentioned method for preparing the fluoride ion adsorbent, preferably, in step (2), in the tin tetrafluoride gasification device, the average rate of tin tetrafluoride gasification is obtained by adding solid tin tetrafluoride per gram of mixed material, and the solid tin tetrafluoride is gasified at a rate of 1-3g / min.

[0015] In the above-mentioned method for preparing the fluoride ion adsorbent, preferably, in step (2), the introduction rate of the mixed gas formed by nitrogen and oxygen is 10-15 mL / min per gram of the mixed material.

[0016] In the above-mentioned method for preparing the fluoride ion adsorbent, preferably, in step (3), the temperature of the second-stage calcination is 500-800° C., and the calcination time is 80-120 min.

[0017] In the above-mentioned method for preparing the fluoride ion adsorbent, preferably, in step (3), the water vapor atmosphere is a water vapor atmosphere obtained by vaporizing water at 100° C., and the average rate of water vaporization is 5-10 g / min.

[0018] In the above-mentioned method for preparing the fluoride ion adsorbent, preferably, in step (4), the water immersion solid-liquid ratio is (4-8):1, the ratio unit is g / mL, the stirring rate of the water immersion process is 20-50rpm, the water immersion temperature is 70-95°C, and the water immersion time is 40-80min.

[0019] As a general inventive concept, the present invention also provides a fluoride ion adsorbent prepared by the above-mentioned preparation method.

[0020] As a general inventive concept, the present invention also provides a fluoride ion adsorbent prepared by the above-mentioned preparation method or the use of the above-mentioned fluoride ion adsorbent in fluoride-containing wastewater.

[0021] The preparation principle of the fluoride ion adsorbent of the present invention is:

[0022] Ferrous oxide, ferric disulfide and calcium chloride are selected as raw materials. In a first-stage roasting process, ferric disulfide is used to reduce part of the ferric oxide to magnetic ferric oxide. At the same time, by controlling the first-stage roasting atmosphere, part of the ferric disulfide is decomposed to obtain pyrrhotite. The calcium chloride added in the first-stage roasting process will also form calcium sulfate. In the first-stage roasting process, ferric oxide, ferric oxide, pyrrhotite and calcium sulfate are sintered with each other, and gaseous sulfur dioxide is formed in the first-stage roasting process, so that the obtained mixed sintered body is loose and porous. Since the roasting atmosphere contains tin tetrafluoride gas, tin tetrafluoride can be adsorbed in the pores of the sintered body. The reaction formula involved in this step is:

[0023] FeS2+Fe2O3→Fe3O4+SO2,

[0024] FeS2+O2→Fe7S8+SO2,

[0025] CaCl2+SO2+O2→CaSO4+Cl2.

[0026] Then, in the second stage of calcination, it is carried out in a water vapor atmosphere. Due to the presence of water vapor, the tin tetrafluoride adsorbed in the sintered body is converted into tin dioxide and the sintered body is activated. The reaction involved in this step is:

[0027] SnF4+H2O→SnO2+HF.

[0028] Finally, the sintered body is soaked in water to remove part of the calcium sulfate, thereby obtaining an adsorbent.

[0029] The adsorbent has a strong ability to adsorb fluorine in the solution. The adsorbent is added into fluorine-containing wastewater, reacts for a certain period of time, and then a magnetic separation device is used to magnetically separate the adsorbent adsorbed with fluorine ions. The process is simple.

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] The present invention selects ferric oxide, ferric disulfide and calcium chloride as raw materials and combines the process control of two-stage roasting. The adsorbent obtained by water immersion has the characteristics of stable structure, large fluorine adsorption capacity, fast fluorine adsorption rate, etc., and the adsorbent can be separated from the solution without liquid-solid separation. DETAILED DESCRIPTION

[0032] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully in combination with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0033] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0034] Unless otherwise specified, all reagents and raw materials used in the present invention are commercially available products or products that can be prepared by known methods.

[0035] The fluorine-containing waste liquid used in the following examples and comparative examples is fluorine-containing waste water generated by a waste power battery recycling enterprise during the battery recycling process, and its composition is shown in Table 1.

[0036] Table 1 Fluorine-containing waste liquid composition

[0037] element F Fe Ni Mn Co Al pH Content (g / L) 0.13 2.37 0.59 1.06 0.41 0.72 2.4

[0038] Embodiment 1:

[0039] A method for preparing a fluoride ion adsorbent of the present invention comprises the following steps:

[0040] (1) Mix ferric oxide, ferric disulfide and calcium chloride in a mass ratio of 10:1.5:0.1 to obtain a mixture.

[0041] (2) subjecting the mixture obtained in step (1) to a first-stage roasting in an atmosphere containing tin tetrafluoride gas, wherein the first-stage roasting temperature is 900° C. and the roasting time is 80 min, to obtain a first-stage roasted slag; wherein, calculated per gram of the mixture, the atmosphere containing tin tetrafluoride gas is a mixture of nitrogen and oxygen in a volume ratio of 10:1, which is then introduced into a tin tetrafluoride gasification device at a rate of 12 mL / min to form a mixed gas with gaseous tin tetrafluoride, and the average rate of tin tetrafluoride gasification in the tin tetrafluoride gasification device is 2 g / min.

[0042] (3) subjecting the first-stage calcined slag obtained in step (2) to a second-stage calcination in a water vapor atmosphere at a temperature of 700° C. and a calcination time of 90 min to obtain a second-stage calcined slag, wherein the water vapor atmosphere is formed by vaporizing water at 100° C. to obtain water vapor, and the average rate of water vaporization is controlled at 9 g / min.

[0043] (4) The second-stage roasting slag is soaked in water, the solid-liquid ratio of the water soaking is 6:1, the ratio unit is g / mL, the water soaking time is 60 minutes, the water soaking temperature is 80°C, the stirring speed during the water soaking process is 35 rpm, and after the water soaking is completed, the filter residue is dried at 85°C for 6 hours to obtain a fluoride ion adsorbent.

[0044] The adsorbent was added to the fluorine-containing waste liquid shown in Table 1, the added amount was controlled to be 0.8 g / L, the adsorption time was 1 h, and the adsorption temperature was 30°C; after the adsorption was completed, the adsorbent was sucked out with a magnet, and the fluorine content in the solution was detected. The fluorine adsorption rate was calculated to be 98.3%, and the fluorine adsorption amount of the adsorbent was 159.7 mg / g.

[0045] Embodiment 2:

[0046] A method for preparing a fluoride ion adsorbent of the present invention comprises the following steps:

[0047] (1) Ferrous oxide, ferric disulfide and calcium chloride are mixed in a mass ratio of 12:1:0.08 to obtain a mixture.

[0048] (2) subjecting the mixture obtained in step (1) to a first-stage roasting in an atmosphere containing tin tetrafluoride gas, wherein the first-stage roasting temperature is 1000° C. and the roasting time is 60 min, to obtain a first-stage roasted slag; wherein, calculated per gram of the mixture, the atmosphere containing tin tetrafluoride gas is a mixture of nitrogen and oxygen in a volume ratio of 10:1, which is then introduced into a tin tetrafluoride gasification device at a rate of 15 mL / min to form a mixed gas with gaseous tin tetrafluoride, and the average rate of gasification of solid tin tetrafluoride in the tin tetrafluoride gasification device is 3 g / min.

[0049] (3) subjecting the first-stage calcined slag obtained in step (2) to a second-stage calcination in a water vapor atmosphere at a temperature of 800° C. and a calcination time of 60 min to obtain a second-stage calcined slag, wherein the water vapor atmosphere is formed by vaporizing water at 100° C. to obtain water vapor, and the average rate of water vaporization is controlled at 10 g / min.

[0050] (4) The second-stage roasting slag is soaked in water, the solid-liquid ratio of the water soaking is 5:1, the ratio unit is g / mL, the water soaking time is 60 minutes, the water soaking temperature is 80°C, the stirring speed during the water soaking process is 35 rpm, and after the water soaking is completed, the filter residue is dried at 85°C for 6 hours to obtain a fluoride ion adsorbent.

[0051] The adsorbent was added to the fluorine-containing waste liquid shown in Table 1, the added amount was controlled to be 0.8 g / L, the adsorption time was 1 h, and the adsorption temperature was 30°C; after the adsorption was completed, the adsorbent was sucked out with a magnet, and the fluorine content in the solution was detected. It was calculated that the fluorine adsorption rate was 99.7%, and the fluorine adsorption amount of the adsorbent was 162.0 mg / g.

[0052] Embodiment 3:

[0053] A method for preparing a fluoride ion adsorbent of the present invention comprises the following steps:

[0054] (1) Ferrous oxide, ferric disulfide and calcium chloride are mixed in a mass ratio of 11:1:0.08 to obtain a mixture.

[0055] (2) subjecting the mixture obtained in step (1) to a first-stage roasting in an atmosphere containing tin tetrafluoride gas, wherein the first-stage roasting temperature is 800° C. and the roasting time is 70 min, to obtain a first-stage roasted slag; wherein, calculated per gram of the mixture, the atmosphere containing tin tetrafluoride gas is a mixture of nitrogen and oxygen in a volume ratio of 9.5:1, which is then introduced into a tin tetrafluoride gasification device at a rate of 13 mL / min to form a mixed gas with gaseous tin tetrafluoride, and the average rate of gasification of solid tin tetrafluoride in the tin tetrafluoride gasification device is 2.5 g / min.

[0056] (3) subjecting the first-stage calcined slag obtained in step (2) to a second-stage calcination in a water vapor atmosphere at a temperature of 750° C. and a calcination time of 80 min to obtain a second-stage calcined slag, wherein the water vapor atmosphere is formed by gasifying water at 100° C. to obtain water vapor, and the average rate of water vaporization is controlled at 8 g / min.

[0057] (4) The second-stage roasting slag is soaked in water, the solid-liquid ratio of the water soaking is 5:1, the ratio unit is g / mL, the water soaking time is 60 minutes, the water soaking temperature is 80°C, the stirring speed during the water soaking process is 35 rpm, and after the water soaking is completed, the filter residue is dried at 85°C for 6 hours to obtain a fluoride ion adsorbent.

[0058] The adsorbent was added to the fluorine-containing waste liquid shown in Table 1, the added amount was controlled to be 0.8 g / L, the adsorption time was 1 h, and the adsorption temperature was 30°C; after the adsorption was completed, the adsorbent was sucked out with a magnet, and the fluorine content in the solution was detected. It was calculated that the fluorine adsorption rate was 96.2%, and the fluorine adsorption amount of the adsorbent was 156.3 mg / g.

[0059] Comparative Example 1:

[0060] In this comparative example, the fluoride ion adsorbent is directly selected as the second-stage calcined slag prepared in step (3) of Example 3.

[0061] The second-stage roasting slag was added to the fluorine-containing waste liquid shown in Table 1, the addition amount was controlled to be 0.8 g / L, the adsorption time was 1 h, and the adsorption temperature was 30°C; after the adsorption was completed, the adsorbent was sucked out with a magnet, and the fluorine content in the solution was detected. It was calculated that the fluorine adsorption rate was 84.6%, and the fluorine adsorption amount of the adsorbent was 137.5 mg / g.

[0062] Comparative Example 2:

[0063] In this comparative example, the first-stage calcined slag prepared in step (1) of Example 3 was directly selected as the fluoride ion adsorbent.

[0064] A section of calcined slag was added into the fluorine-containing waste liquid shown in Table 1, the added amount was controlled to be 0.8 g / L, the adsorption time was 1 h, and the adsorption temperature was 30°C; after the adsorption was completed, the magnet could not absorb the adsorbent, and the adsorbent was separated by filtration, and the fluorine content in the solution was detected. It was calculated that the fluorine adsorption rate was 57.9%, and the fluorine adsorption amount of the adsorbent was 94.1 mg / g.

[0065] Comparative Example 3:

[0066] The fluoride ion adsorbent of this comparative example is different from that of Example 3 in that the first-stage calcination of step (2) is omitted and the second-stage calcination is directly performed. That is, the only difference from Example 3 is that step (2) is omitted, and other processes and parameters are the same as those of Example 3.

[0067] The adsorbent prepared in this comparative example was added to the fluorine-containing waste liquid shown in Table 1, the added amount was controlled to be 0.8 g / L, the adsorption time was 1 h, and the adsorption temperature was 30°C; after the adsorption was completed, the adsorbent was sucked out with a magnet, and the fluorine content in the solution was detected. It was calculated that the fluorine adsorption rate was 13.7%, and the fluorine adsorption amount of the adsorbent was 22.3 mg / g.

[0068] Comparative Example 4:

[0069] The fluoride ion adsorbent of this comparative example is different from that of Example 3 in that the atmosphere containing tin tetrafluoride gas in step (2) does not contain oxygen, and the other processes and parameters are the same as those of Example 3.

[0070] The adsorbent of this comparative example was added to the fluorine-containing waste liquid shown in Table 1, the added amount was controlled to be 0.8 g / L, the adsorption time was 1 h, and the adsorption temperature was 30°C; after the adsorption was completed, the magnet could not absorb the adsorbent, and the adsorbent was separated by filtration. The fluorine content in the solution was detected, and the fluorine adsorption rate was calculated to be 7.3%, and the fluorine adsorption amount of the adsorbent was 11.9 mg / g.

[0071] Comparative Example 5:

[0072] The fluoride ion adsorbent of this comparative example is different from that of Example 3 in that the atmosphere containing tin tetrafluoride gas in step (2) does not contain nitrogen, and the other processes and parameters are the same as those of Example 3.

[0073] The adsorbent of this comparative example was added to the fluorine-containing waste liquid shown in Table 1, the added amount was controlled to be 0.8 g / L, the adsorption time was 1 h, and the adsorption temperature was 30°C; after the adsorption was completed, only 67.3% of the adsorbent could be sucked out by a magnet, and then the adsorbent was separated by filtration, the fluorine content in the solution was detected, and the fluorine adsorption rate was calculated to be 85.1%, and the fluorine adsorption amount of the adsorbent was 138.3 mg / g.

Claims

1. A method for preparing a fluoride ion adsorbent, characterized in that: The following steps are involved: (1) Evenly mixing ferric oxide, ferric disulfide and calcium chloride to obtain a mixture; wherein the mass ratio of ferric oxide, ferric disulfide and calcium chloride is (10-12):(1-2):(0.08-0.1); (2) subjecting the mixed material to a first stage roasting in an atmosphere containing tin tetrafluoride gas to obtain a first stage roasting slag; the atmosphere containing tin tetrafluoride gas is a mixed atmosphere of tin tetrafluoride gas, nitrogen and oxygen; (3) subjecting the first-stage calcined slag to a second-stage calcination in a water vapor atmosphere to obtain a second-stage calcined slag; (4) Soaking the second-stage calcined slag in water, and filtering it after the soaking is completed to obtain the fluoride ion adsorbent.

2. The method for preparing a fluoride ion adsorbent according to claim 1, characterized in that: In step (2), the temperature of the first stage of roasting is 900-1000° C., and the time of the first stage of roasting is 60-90 minutes.

3. The method for preparing a fluoride ion adsorbent according to claim 1, characterized in that: In step (2), the mixed atmosphere of tin tetrafluoride gas, nitrogen and oxygen is a mixed gas formed by uniformly mixing nitrogen and oxygen in a volume ratio of 9:1-10:1 and then passing the mixed gas into a tin tetrafluoride gasification device.

4. The method for preparing a fluoride ion adsorbent according to claim 3, characterized in that: In step (2), in the tin tetrafluoride gasification device, the average rate of tin tetrafluoride gasification is 1-3 g / min for each gram of mixed material processed.

5. The method for preparing a fluoride ion adsorbent according to claim 3, characterized in that: In step (2), the rate of introduction of the mixed gas formed by nitrogen and oxygen is 10-15 mL / min for each gram of the mixed material treated.

6. The method for preparing a fluoride ion adsorbent according to claim 1, characterized in that: In step (3), the temperature of the second stage roasting is 500-800°C, and the roasting time is 80-120 minutes.

7. The method for preparing a fluoride ion adsorbent according to claim 1, characterized in that: In step (3), the water vapor atmosphere is a water vapor atmosphere obtained by vaporizing water at 100° C., and the average rate of water vaporization is 5-10 g / min.

8. A fluoride ion adsorbent, characterized in that: The method according to any one of claims 1 to 7 is used to prepare the present invention.

9. Use of a fluoride ion adsorbent prepared by the preparation method according to any one of claims 1 to 7 or the fluoride ion adsorbent according to claim 8 in fluoride-containing wastewater.