Deep fluorine removal agent and application method thereof

Abstract

This invention discloses a deep defluorination agent and its application method, specifically relating to the field of defluorination agents (GMS-FS series products). It includes a valence-state switching active phase, a reaction interface building component, a dynamic electronic regulation component, and a structure adjustment and protection component. The valence-state switching active phase provides a reversible valence-state transition reaction center, achieving specific capture of fluoride ions through an electron trapping effect when interacting with them. The reaction interface building component forms a polar gradient interface layer on the surface of the defluorination agent, guiding fluoride ions to migrate towards the active center and locally enrich them, thereby improving defluorination efficiency. By constructing a rare metal valence-state switching active phase with La2O3 and UO2 as its core, combined with a polar gradient interface guiding layer and a dynamic electronic regulation mechanism, preferential migration and specific capture of fluoride ions are induced in a multi-ion coexistence environment, achieving stable deep defluorination under high salinity and highly competitive ion conditions.

Description

Technical Field

[0001] This invention relates to the field of defluorinating agents, and more specifically, to a deep defluorinating agent and its application method. Background Technology

[0002] In high-salinity or complex ionic environments, such as seawater desalination, lithium extraction from salt lakes, and treatment of industrial high-salinity wastewater, defluorinating agents not only need to efficiently capture fluoride ions, but also must maintain selectivity under the competitive action of multiple coexisting ions.

[0003] Conventional defluorinating agents mainly rely on electrostatic adsorption or simple complexation mechanisms, and are ineffective at removing high concentrations of Cl. - SO4 2- NO3 - When anions coexist, nonspecific occupancy of binding sites is very likely to occur, leading to a sharp decline in the ability to capture fluoride ions.

[0004] As salinity increases and the types of ions become more complex, the preferential adsorption status of fluoride ions in the defluorination system is broken. Not only does the defluorination rate decrease significantly, but under certain conditions, reverse adsorption phenomena, in which fluoride ions are released a second time, occur, completely destroying the effect of deep defluorination.

[0005] Therefore, how to maintain the specific capture of fluoride ions by the defluorinating agent under extremely high salt and highly competitive ion conditions has become a difficult problem to be solved in deep defluorination. Summary of the Invention

[0006] To overcome the aforementioned deficiencies in the prior art, embodiments of the present invention provide a deep defluorination agent and its application method. By constructing a rare metal valence state switching active phase with La2O3 and UO2 as the core, and combining it with a polar gradient interface guiding layer and a dynamic electronic regulation mechanism, the agent induces preferential migration and specific capture of fluoride ions in a multi-ion coexistence environment, thereby achieving stable deep defluorination under high salinity and strong competitive ion conditions, thus solving the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a deep defluorination agent (GMS-FS series products), wherein the defluorination agent comprises the following components, in parts by weight:

[0008] Valence state switching active phase: 35-42 parts, wherein the valence state switching active phase is used to provide a reversible valence state transition reaction center and achieves specific capture of fluoride ions through the electron trapping effect when interacting with fluoride ions;

[0009] The reaction interface building component is 20-30 parts. The reaction interface building component is used to form a polar gradient interface layer on the surface of the defluorinating agent, guide fluoride ions to migrate to the active center and locally enrich them, thereby improving the defluorinating efficiency.

[0010] The dynamic electronic regulation component consists of 8 to 15 parts. The dynamic electronic regulation component is used to dynamically adjust the local electronic potential field distribution during the defluorination process and suppress the valence instability or structural collapse of rare metal active centers caused by sudden changes in electron density.

[0011] The structure adjustment and protection component comprises 10-15 parts, which is used to construct a flexible protective layer on the surface of the defluorinating agent to enhance its resistance to salting out, high shear or mechanical disturbance, and prevent carrier peeling and adsorption site deterioration.

[0012] In a preferred embodiment, the valence-switching active phase comprises the following components, in parts by weight:

[0013] Lanthanide oxides, including those selected from La₂O₃, with a particle size range of 20–80 nm, serve to provide low-barrier valence state switching channels (La₂O₃). 3+ / La 2+ (Transformation) to excite responsive capture of fluoride ions;

[0014] Actinide oxides, including those selected from UO2 with a particle size range of 30–100 nm, act to form a highly polarized electric field region, enhancing the directional enrichment ability of small-radius, highly electronegative ions.

[0015] In a preferred embodiment, the valence-switching active phase further includes a doped metal oxide, wherein the metal oxide includes Pr6O. 11 Alternatively, CeO2, doped metal oxides are used to regulate the overall electron cloud density and polarization capability, stabilize the multi-valence equilibrium environment, and the doped metal oxides account for 5-15% of the total weight of the valence switching active phase, wherein the weight ratio of lanthanide oxides to actinide oxides is 8:2.

[0016] In a preferred embodiment, the reaction interface building component comprises the following components, in parts by weight:

[0017] Functionalized cerium oxide (CeO2), with a particle size of 5–30 nm, is surface-modified with carboxyl or hydroxyl functional groups to construct highly polar adsorption sites and form directional ion migration microregions in a porous structure, with a specific surface area of ​​not less than 120 m². 2 / g;

[0018] Nano-titanium oxide (TiO2), with a particle size distribution of 5–20 nm, is used to adjust the ratio of micropores to mesopores in a porous structure, thereby improving ion transport rate and reaction interface stability. The weight ratio of CeO2 to TiO2 is 3:2.

[0019] In a preferred embodiment, the dynamic electronic control component comprises the following components, in parts by weight:

[0020] Manganese oxides, including those selected from MnO2, have hole self-trapping properties and are used to release electron traps in local high-energy electron accumulation regions, thus buffering electron density fluctuations.

[0021] Vanadium oxides, including those selected from V2O5, have low interstitial energy characteristics and are used to construct electron migration intermediates during the defluorination reaction to maintain the equilibrium state of valence state switching, wherein the weight ratio of MnO2 to V2O5 is 2:1.

[0022] In a preferred embodiment, the structural conditioning and protective component comprises the following components, in parts by weight:

[0023] Silane crosslinking agents, including those selected from 3-aminopropyltriethoxysilane (APTES), form a dense protective layer by covalently bonding with hydroxyl groups on the surface of the carrier, thereby stabilizing the microenvironment structure.

[0024] Hydrolyzed polyvinyl alcohol (PVA) with a molecular weight of 50,000 to 100,000 forms an auxiliary physical buffer network layer, which disperses local mechanical stress and improves the overall structural flexibility. The weight ratio of silane crosslinking agent to PVA is 3:2.

[0025] In a preferred embodiment, the valence-switching active phase is transmitted via La 3+ / La 2+ and U 4+ / U 6+ The reversible valence state transition induces the formation of electron traps in the presence of fluoride ions, thereby achieving specific locking and capture of fluoride ions;

[0026] And / or the reaction interface building components construct a polar guiding region in the microporous / mesoporous interface region to promote the enrichment of fluoride ions and the contact efficiency of active centers.

[0027] And / or the dynamic electronic regulation component releases or absorbs electrons during the reaction process, thereby achieving auxiliary stabilization of the valence state switching of rare metal active centers and suppressing electronic instability;

[0028] And / or the structure adjustment and protection components protect the surface structure integrity of the carrier in high-salt, high-shear environments, maintaining the long-term stability of the overall defluorination performance of the defluorinating agent.

[0029] In a preferred embodiment, the method of applying the deep defluoridating agent includes introducing the defluoridating agent into fluoride-containing water, using the electronegativity of fluoride ions to guide their migration to the carrier surface and bind to rare metal centers with switchable valence states, thereby achieving the capture and fixation of fluoride ions.

[0030] In a preferred embodiment, the method of applying the deep defluoridating agent includes dispersing the defluoridating agent in fluoride-containing water, relying on the electronic polarization between active sites and the local pore structure to guide the migration of fluoride ions and undergo a specific complexation reaction, thereby completing the removal of fluoride ions.

[0031] The technical effects and advantages of this invention are as follows:

[0032] This invention discloses a deep defluorination agent (GMS-FS series products), which constructs a valence-state switching active phase by combining La2O3 and UO2, and maintains a local polarization potential field by combining dynamic electronic regulation components, enabling the defluorination agent to achieve defluorination in Cl... - SO4 2- NO3 - Even under conditions of multi-ion competition, it can still induce the electron trapping effect of fluoride ions, maintain the specific capture capability, and solve the problems of decreased defluorination rate and reverse adsorption under complex environments.

[0033] The present invention discloses a deep defluorination agent (GMS-FS series products), which constructs a polar gradient interface layer on the surface of the defluorination agent composed of carboxyl / hydroxyl functionalized cerium oxide and nano titanium oxide, thereby directionally guiding fluoride ions to preferentially migrate to the active center, improving the fluoride ion enrichment efficiency, enhancing the initial response rate of the defluorination reaction and stabilizing the adsorption process.

[0034] The deep defluorination agent (GMS-FS series products) of this invention dynamically adjusts the local electronic potential field during the reaction process by setting up a dynamic electronic control system composed of manganese oxide and vanadium oxide, buffering the valence state fluctuations of rare metal active centers, maintaining continuous and stable reversible valence state switching, and improving the stability and anti-failure ability of long-cycle defluorination.

[0035] The present invention discloses a deep defluorinating agent (GMS-FS series products), which introduces a 3-aminopropyltriethoxysilane crosslinking agent and hydrolyzed polyvinyl alcohol to construct a flexible protective layer. Under extreme water environments such as high salinity and shear disturbance, it effectively prevents the defluorinating agent particle structure from breaking down and the adsorption sites from peeling off, thus extending the service life of the material and maintaining the consistency of defluorinating performance. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] The present invention provides a deep defluorination agent and its application method, including 5 examples and 2 comparative examples.

[0038] Example 1: A deep defluorination agent, comprising the following components, in parts by weight:

[0039] Forty portions of valence-switching active phases were provided, comprising: La2O3 (particle size 20–80 nm), UO2 (particle size 30–100 nm), and Pr6O. 11 (It accounts for 10% of the total weight of the active phase for valence switching, and the weight ratio of lanthanide oxide to actinide oxide is 8:2), which is used to provide a reversible valence switching reaction center and achieves specific capture of fluoride ions through the electron trapping effect when interacting with fluoride ions;

[0040] 25 parts of the reaction interface building component, wherein the reaction interface building component includes: functionalized cerium oxide (CeO2, particle size 5-30 nm, specific surface area not less than 120 m²). 2 / g, surface-modified carboxyl functional groups) and nano titanium dioxide (TiO2, particle size 5-20nm), wherein the weight ratio of CeO2 to TiO2 is 3:2, are used to form a polar gradient interface layer on the surface of the defluorinating agent, guiding fluoride ions to migrate to the active center and locally enrich them.

[0041] Ten parts of a dynamic electronic control component are included, comprising MnO2 and V2O5 (in a weight ratio of 2:1), wherein MnO2 has hole self-capture characteristics and V2O5 has low-energy gap characteristics, which are used to dynamically adjust the local electronic potential field distribution during the defluorination process.

[0042] Thirteen parts of a structure-modifying and protective component are included, comprising 3-aminopropyltriethoxysilane (APTES) and hydrolyzed polyvinyl alcohol (PVA, molecular weight 50,000-100,000), wherein the weight ratio of APTES to PVA is 3:2. This component is used to construct a flexible protective layer on the surface of the defluorinating agent to enhance its resistance to salting out, shearing, or mechanical disturbance.

[0043] Example 2: A deep defluorination agent, comprising the following components, in parts by weight:

[0044] 38 parts of valence state switching active phase, the valence state switching active phase including: La2O3 (particle size 20-80nm), UO2 (particle size 30-100nm), CeO2 (8% of the total weight of the valence state switching active phase, the weight ratio of lanthanide oxide to actinide oxide is 8:2), are used to provide reversible valence state transition reaction centers;

[0045] The reaction interface building components consist of 28 parts, including: functionalized cerium oxide (CeO2, particle size 5-30 nm, specific surface area not less than 120 m²). 2 / g, surface-modified hydroxyl functional groups) and nano titanium dioxide (TiO2, particle size 5-20nm), wherein the weight ratio of CeO2 to TiO2 is 3:2;

[0046] The dynamic electronic regulation component comprises 12 parts, wherein the dynamic electronic regulation component includes MnO2 and V2O5 (in a weight ratio of 2:1).

[0047] The structure-modifying and protective component comprises 12 parts, wherein the structure-modifying and protective component includes 3-aminopropyltriethoxysilane (APTES) and hydrolyzed polyvinyl alcohol (PVA, molecular weight 50,000 to 100,000), wherein the weight ratio of APTES to PVA is 3:2.

[0048] Example 3: A deep defluorination agent, comprising the following components, in parts by weight:

[0049] Forty-two valence-switching active phases were included, comprising: La₂O₃ (particle size 20–80 nm), UO₂ (particle size 30–100 nm), and Pr₆O₂. 11 (It accounts for 12% of the total weight of the active phase for valence switching, and the weight ratio of lanthanide oxides to actinide oxides is 8:2).

[0050] 23 parts of the reaction interface building components, including: functionalized cerium oxide (CeO2, particle size 5-30 nm, specific surface area not less than 120 m²). 2 / g, surface-modified carboxyl functional groups) and nano-titanium oxide (TiO2, particle size 5-20nm), wherein the weight ratio of CeO2 to TiO2 is 3:2;

[0051] Ten parts of dynamic electronic regulation component, wherein the dynamic electronic regulation component includes: MnO2 and V2O5 (weight ratio of 2:1).

[0052] The structure-modifying and protective component comprises 15 parts, wherein the structure-modifying and protective component includes 3-aminopropyltriethoxysilane (APTES) and hydrolyzed polyvinyl alcohol (PVA, molecular weight 50,000 to 100,000), wherein the weight ratio of APTES to PVA is 3:2.

[0053] Example 4: A deep defluorination agent, comprising the following components, in parts by weight:

[0054] 36 portions of valence-switching active phase, comprising: La2O3 (particle size 20-80 nm), UO2 (particle size 30-100 nm), and CeO2 (accounting for 5% of the total weight of the valence-switching active phase, with a weight ratio of lanthanide oxide to actinide oxide of 8:2).

[0055] 30 parts of the reaction interface building component, wherein the reaction interface building component includes: functionalized cerium oxide (CeO2, particle size 5-30 nm, specific surface area not less than 120 m²). 2 / g, surface-modified carboxyl functional groups) and nano-titanium oxide (TiO2, particle size 5-20nm), wherein the weight ratio of CeO2 to TiO2 is 3:2;

[0056] Nine parts of dynamic electronic regulation component, the dynamic electronic regulation component including: MnO2 and V2O5 (weight ratio of 2:1).

[0057] Thirteen parts of the structure-modifying and protective components are included, comprising: 3-aminopropyltriethoxysilane (APTES) and hydrolyzed polyvinyl alcohol (PVA, molecular weight 50,000-100,000), wherein the weight ratio of APTES to PVA is 3:2.

[0058] Example 5: A deep defluorination agent, comprising the following components, in parts by weight:

[0059] 35 portions of valence-switching active phases, comprising: La2O3 (particle size 20–80 nm), UO2 (particle size 30–100 nm), and Pr6O. 11 (It accounts for 7% of the total weight of the active phase for valence switching, and the weight ratio of lanthanide oxides to actinide oxides is 8:2).

[0060] The reaction interface building components consist of 26 parts, including: functionalized cerium oxide (CeO2, particle size 5-30 nm, specific surface area not less than 120 m²). 2 / g, surface-modified hydroxyl functional groups) and nano titanium dioxide (TiO2, particle size 5-20nm), wherein the weight ratio of CeO2 to TiO2 is 3:2;

[0061] The dynamic electronic regulation component comprises 15 parts, wherein the dynamic electronic regulation component includes MnO2 and V2O5 (in a weight ratio of 2:1).

[0062] The structure-modifying and protective component comprises 14 parts, wherein the structure-modifying and protective component includes 3-aminopropyltriethoxysilane (APTES) and hydrolyzed polyvinyl alcohol (PVA, molecular weight 50,000 to 100,000), wherein the weight ratio of APTES to PVA is 3:2.

[0063] Comparative Example 1: A deep defluorination agent, comprising the following components in parts by weight:

[0064] Forty parts of valence state switching active phase, the valence state switching active phase includes: La2O3 (particle size 20-80nm), without UO2 actinide oxide, using only La2O3 as a single component, the La2O3 is used to provide reversible valence state transition reaction center;

[0065] 25 parts of the reaction interface building component, wherein the reaction interface building component includes: functionalized cerium oxide (CeO2, particle size 5-30 nm, specific surface area not less than 120 m²). 2 / g, surface-modified carboxyl functional groups) and nano-titanium oxide (TiO2, particle size 5-20nm), wherein the weight ratio of CeO2 to TiO2 is 3:2;

[0066] Ten parts of dynamic electronic regulation component, wherein the dynamic electronic regulation component includes: MnO2 and V2O5 (weight ratio of 2:1).

[0067] Thirteen parts of the structure-modifying and protective components are included, comprising: 3-aminopropyltriethoxysilane (APTES) and hydrolyzed polyvinyl alcohol (PVA, molecular weight 50,000-100,000), wherein the weight ratio of APTES to PVA is 3:2.

[0068] As explained in Comparative Example 1, compared with Example 1, this comparative example lacks actinide oxide UO2, and no rare metal high polarization electric field region is formed, which is expected to lead to a decrease in the directional enrichment ability of fluoride ions and a decrease in fluoride removal efficiency.

[0069] Comparative Example 2: A deep defluorination agent, comprising the following components in parts by weight:

[0070] Thirty-eight portions of valence-switching active phases were included, comprising: La₂O₃ (particle size 20–80 nm), UO₂ (particle size 30–100 nm), and Pr₆O₂. 11 (It accounts for 8% of the total weight of the active phase for valence switching, and the weight ratio of lanthanide oxides to actinide oxides is 8:2).

[0071] The reaction interface building components consist of 28 parts, including: functionalized cerium oxide (CeO2, particle size 5-30 nm, specific surface area not less than 120 m²). 2 / g, surface-modified hydroxyl functional groups) and nano titanium dioxide (TiO2, particle size 5-20nm), wherein the weight ratio of CeO2 to TiO2 is 3:2;

[0072] The dynamic electronic control component is 0 parts, and no dynamic electronic control components such as MnO2 and V2O5 are added to the deep defluorination agent;

[0073] The structure-modifying and protective component comprises 12 parts, wherein the structure-modifying and protective component includes 3-aminopropyltriethoxysilane (APTES) and hydrolyzed polyvinyl alcohol (PVA, molecular weight 50,000 to 100,000), wherein the weight ratio of APTES to PVA is 3:2.

[0074] As explained in Comparative Example 2, compared with Example 2, this comparative example did not include the dynamic electronic regulation components MnO2 and V2O5, and therefore could not dynamically adjust the local electronic potential field, which is expected to lead to a decrease in the stability of valence state switching and a deterioration of long-term defluorination performance.

[0075] Table 1: Comprehensive Test Table for Fluorine Removal Performance

[0076]

[0077] According to the interpretation of Table 1, the performance of the examples is better than that of the comparative examples, especially Example 3 (high doping ratio and complete dynamic control) which performs the best.

[0078] Table 2: Cyclic Stability Test Table

[0079]

[0080] Regarding the interpretation of Table 2, the structural adjustment and protective components in the embodiments effectively delayed deactivation, while the failure of the comparative embodiment was accelerated.

[0081] Table 3: Fluorine Removal Performance under Ion Competition Environment

[0082]

[0083] As interpreted in Table 3, the complete structural system effectively resists multi-ion interference, and the adsorption selectivity of the comparative proportion decreases significantly.

[0084] Table 4: Microstructure and Electronic Performance Test Table

[0085]

[0086] The interpretation of Table 4 shows that the surface structure and electronic performance parameters of the examples are better than those of the comparative examples, which fully supports the view that the difference in defluorination performance comes from the structural design.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A deep defluorination agent, characterized in that, The defluorinating agent comprises the following components, in parts by weight: Valence state switching active phase: 35-42 parts, wherein the valence state switching active phase is used to provide a reversible valence state transition reaction center and achieves specific capture of fluoride ions through the electron trapping effect when interacting with fluoride ions; The reaction interface building component is 20-30 parts. The reaction interface building component is used to form a polar gradient interface layer on the surface of the defluorinating agent, guide fluoride ions to migrate to the active center and locally enrich them, thereby improving the defluorinating efficiency. The dynamic electronic regulation component consists of 8 to 15 parts. The dynamic electronic regulation component is used to dynamically adjust the local electronic potential field distribution during the defluorination process and suppress the valence instability or structural collapse of rare metal active centers caused by sudden changes in electron density. The structure adjustment and protection component is 10-15 parts. The structure adjustment and protection component is used to construct a flexible protective layer on the surface of the defluorinating agent to enhance the resistance to salting out, shearing or mechanical disturbance and prevent carrier peeling and adsorption site deterioration. The valence-switching active phase comprises the following components, in parts by weight: Lanthanide oxides, including those selected from La2O3, with a particle size range of 20–80 nm, serve to provide low-barrier valence state switching channels to excite responsive capture of fluoride ions; Actinide oxides, including those selected from UO2 with a particle size range of 30–100 nm, act to form a region with a high polarization electric field; The dynamic electronic control component includes the following components, in parts by weight: Manganese oxides, including those selected from MnO2, have hole self-trapping properties and are used to release electron traps in local high-energy electron accumulation regions, thus buffering electron density fluctuations. Vanadium oxides, including those selected from V2O5, have low interstitial energy characteristics and are used to construct electron migration intermediates during the defluorination reaction to maintain the valence state switching equilibrium. The weight ratio of MnO2 to V2O5 is 2:

1. The reaction interface building components include the following components, in parts by weight: Functionalized cerium oxide (CeO2) with a particle size of 5–30 nm, modified with carboxyl or hydroxyl functional groups on its surface to construct highly polar adsorption sites and form directional ion migration regions in the porous structure, with a specific surface area of ​​not less than 120 m². 2 / g; Nano-sized titanium dioxide (TiO2) with a particle size distribution of 5–20 nm is used to adjust the ratio of micropores to mesopores in a porous structure, thereby improving ion transport rate and reaction interface stability. The weight ratio of CeO2 to TiO2 is 3:

2. The structural conditioning and protective components include the following components, in parts by weight: Silane crosslinking agents, including those selected from 3-aminopropyltriethoxysilane (APTES), form a protective layer by covalently bonding with hydroxyl groups on the surface of the carrier, thereby stabilizing the microenvironment structure. Hydrolyzed polyvinyl alcohol (PVA) with a molecular weight of 50,000 to 100,000 forms an auxiliary physical buffer network layer, which disperses local mechanical stress and improves the overall structural flexibility. The weight ratio of silane crosslinking agent to PVA is 3:

2.

2. The deep defluorination agent according to claim 1, characterized in that: The valence-switching active phase further includes a doped metal oxide, the metal oxide being selected from Pr6O. 11 Alternatively, CeO2, doped metal oxides are used to regulate the overall electron cloud density and polarization capability, stabilize the multi-valence equilibrium environment, and the doped metal oxides account for 5-15% of the total weight of the valence switching active phase, wherein the weight ratio of lanthanide oxides to actinide oxides is 8:

2.

3. The deep defluorination agent according to claim 2, characterized in that: The valence-switching active phase is via La 3+ / La 2+ and U 4+ / U 6+ The reversible valence state transition induces the formation of electron traps in the presence of fluoride ions, thereby achieving specific locking and capture of fluoride ions; And / or the reaction interface building components construct a polar guiding region in the microporous / mesoporous interface region to promote the enrichment of fluoride ions and the contact efficiency of active centers. And / or the dynamic electronic regulation component releases or absorbs electrons during the reaction process, thereby achieving auxiliary stabilization of the valence state switching of rare metal active centers and suppressing electronic instability; And / or the structure adjustment and protection components protect the integrity of the carrier surface structure under salting-out and shearing conditions, maintaining the long-term stability of the overall defluorination performance of the defluorinating agent.

4. A method for applying a deep defluorination agent, characterized in that: The defluorinating agent described in claim 3 is introduced into fluoride-containing water. The electronegativity of fluoride ions is used to guide their migration to the carrier surface and bind to rare metal centers with switchable valence states. The migration of fluoride ions is guided by the electronic polarization between active sites and the local pore structure, and a specific complexation reaction is carried out, thereby achieving the capture, fixation and removal of fluoride ions.

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