A polyphosphate rare earth ion adsorbent, a preparation method and application thereof

Abstract

The application provides a polyphosphate rare earth ion adsorbent, a preparation method and application thereof, and the polyphosphate rare earth ion adsorbent comprises a porous organic polymer of a phosphate functional group, and the phosphate group has a structure shown in formula I or formula II. The polyphosphate rare earth ion adsorbent has high selectivity, large adsorption capacity, excellent desorption and cycle performance for rare earth ions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of adsorption separation materials, and particularly relates to a polyphosphate rare earth ion adsorbent and a preparation method and application thereof. BACKGROUND

[0002] Rare earth elements are recognized as key strategic metal resources, and ion-type rare earth ore is a unique mineral in China. According to statistics, more than 90% of the world's industrial application of medium and heavy rare earths comes from ion-type rare earth ore in southern China. Due to incomplete leaching of the current process, a large number of ion-type rare earth waste tailings are left over. The leaching tail liquid and leaching water enter rivers and streams with rainwater, resulting in a large amount of low-concentration rare earth wastewater. This not only causes serious loss of rare earth resources, but also causes environmental pollution and harm to human health. At the same time, rare earths are non-renewable resources. With the continuous growth of demand and the increasing requirements of environmental protection, the comprehensive recycling of leaching tail liquid and leaching wastewater has attracted widespread attention and high attention. Selective and efficient enrichment and separation of rare earth elements from complex low-concentration rare earth wastewater is of great importance to the sustainable development of China's rare earth economy and ecological environment.

[0003] The leaching tail liquid and leaching wastewater system of ion-type rare earth ore is characterized by low concentration of rare earth ions (total concentration <100 mg / L) and the presence of a variety of associated ions, including aluminum ions similar in physical and chemical properties to rare earth ions, as well as common sodium, potassium, calcium, and magnesium ions in ores. The enrichment is difficult, and it is urgent to develop new materials and related technologies to efficiently recover rare earth elements from low-concentration wastewater.

[0004] Currently, the methods for extracting rare earths from low-concentration rare earth wastewater mainly include solvent extraction, precipitation, membrane separation, and adsorption. Among them, the adsorption method has the advantages of high adsorption separation efficiency, low cost, and easy operation, and is particularly suitable for the separation and recovery of low-concentration rare earth resources. CN115927885A discloses a method for recovering rare earth elements from rare earth wastewater using phosphoric acid modified kaolin. The selective adsorption of rare earth elements is achieved through the bonding of phosphate groups on the phosphoric acid modified kaolin with rare earth elements. The adsorption rate of rare earth elements can reach more than 90%. CN115894953A discloses a magnetic porous organic polymer material prepared by crosslinking tannic acid and hexachlorotriphosphazene for selective separation and recovery of rare earth ions.

[0005] In addition, the existing adsorbents generally have the disadvantages of small adsorption capacity, low selectivity, complex preparation method, and high cost. Therefore, it is an urgent problem in the field to develop an adsorbent with high selectivity for rare earth ions, high adsorption capacity, high desorption rate, good recyclability, and simple preparation method. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application aims to provide a polyphosphate rare earth ion adsorbent, a preparation method and application thereof, the polyphosphate rare earth ion adsorbent has high selectivity, large adsorption capacity, excellent desorption and cycle performance for rare earth ions.

[0007] To achieve the object of the present application, the present application adopts the following technical solutions:

[0008] In one aspect, the present application provides a polyphosphate rare earth ion adsorbent, the polyphosphate rare earth ion adsorbent comprises a porous organic polymer of a phosphate functional group, the phosphate group has a structure shown in Formula I or Formula II:

[0009]

[0010] wherein R is a benzene ring.

[0011] In the present application, the polyphosphate rare earth ion adsorbent is a porous organic polymer with chain and network formed by phosphorus oxychloride monomers and phenol monomers.

[0012] In the present application, the P-O-R in Formula I or Formula II is formed by substitution reaction of phosphorus oxychloride and phenol monomers.

[0013] In the present application, the "phenol monomer" refers to any one of hydroquinone, 4,4'-dihydroxybenzophenone, phloroglucinol, 1,3,5-tris(4-hydroxyphenyl)benzene.

[0014] Preferably, the phenol monomer comprises phloroglucinol.

[0015] In the present application, by selecting phosphorus oxychloride as raw material and cross-linking with phenol monomers of different functionalities, the adsorbent forms a polymer rich in neutral or acidic phosphate groups, which can coordinate and ion exchange with rare earth ions, thereby adsorbing rare earth ions; and the specific phosphate group can realize high selectivity, high adsorption capacity, excellent desorption performance and cycle performance for rare earth ions.

[0016] Preferably, the pore size of the rare earth ion adsorbent is 2-7 nm, for example, it can be 2.2 nm, 2.4 nm, 2.6 nm, 2.8 nm, 3 nm, 3.2 nm, 3.4 nm, 3.6 nm, 3.8 nm, 4 nm, 4.2 nm, 4.4 nm, 4.6 nm, 4.8 nm, 5 nm, 5.2 nm, 5.4 nm, 5.6 nm, 5.8 nm, 6 nm, 6.2 nm, 6.4 nm, 6.6 nm, 6.8 nm, etc.

[0017] In the present application, the pore size of the rare earth ion adsorbent is characterized by a physical adsorption instrument.

[0018] In a second aspect, the present application provides a preparation method of the rare earth ion adsorbent according to the first aspect, the preparation method comprising:

[0019] The reaction of the phosphorus oxychloride monomer and the phenol monomer is carried out under alkaline conditions at 0°C to obtain the rare earth ion adsorbent.

[0020] Preferably, the reaction is carried out in the presence of a catalyst.

[0021] Preferably, the molar ratio of the catalyst to the phosphorus oxychloride is (3-4):1, for example, it can be 3.15:1, 3.25:1, 3.35:1, 3.45:1, 3.55:1, 3.65:1, 3.75:1, 3.85:1, 3.95:1, 4:1, etc.

[0022] In the present application, the catalyst and the phosphorus oxychloride are in a specific molar ratio, the selectivity and adsorption capacity of the rare earth ion adsorbent to the rare earth ions are the highest, the material is difficult to polymerize when the catalyst is used in too low an amount, the yield is low, and when the catalyst is used in too high an amount, the crosslinking degree is too high, the hydrophobicity is enhanced, the diffusion of the adsorbate is not conducive, and the adsorption performance is greatly reduced.

[0023] Preferably, the catalyst comprises anhydrous triethylamine.

[0024] In the present application, the substitution reaction of the phosphorus oxychloride and the phloroglucinol is carried out under the catalysis of the triethylamine, the phosphate crosslinked polymer can be synthesized by one-step method, the deficiencies of the extractant and the adsorbent in the prior art are made up, the coordination effect and the ion exchange effect are combined, high selectivity and high adsorption capacity, fast adsorption rate, and excellent desorption cycle performance are achieved, the use of the crosslinking agent is avoided, the synthesis process is simplified, and the cost is reduced.

[0025] Preferably, the reaction is carried out in a solvent.

[0026] Preferably, the solvent comprises dichloromethane, acetonitrile.

[0027] In the present application, the initial concentration of the phosphorus oxychloride is 0.4-1.2 mol / L, for example, it can be 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, or 1.1 mol / L.

[0028] Preferably, the reaction is carried out in the presence of a protective atmosphere.

[0029] Preferably, the protective atmosphere comprises nitrogen or argon.

[0030] Preferably, the reaction comprises a polymerization stage and a reflux stage.

[0031] Preferably, the reaction temperature of the polymerization stage is 0°C.

[0032] Preferably, the reaction time of the polymerization stage is 30-40 min, for example, it can be 32 min, 34 min, 36 min, 38 min.

[0033] Preferably, the reaction temperature of the reflux stage is 80-90°C, for example, it can be 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C.

[0034] Preferably, the reaction time of the reflux stage is 15-24 h, for example, it can be 16 h, 18 h, 20 h, 22 h, 24 h, etc.

[0035] In the present application, the reaction is followed by the steps of filtration, washing, Soxhlet extraction and drying.

[0036] Preferably, the washing comprises the steps of washing with hydrochloric acid, ultrapure water and methanol in sequence.

[0037] Preferably, the concentration of the hydrochloric acid is 1-2 mol / L, for example, it can be 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, etc.

[0038] Preferably, the time for washing with hydrochloric acid is 1-2 h, for example, it can be 1.2 h, 1.4 h, 1.6 h, 1.8 h, etc.

[0039] Preferably, the filtrate is washed to neutral with ultrapure water.

[0040] Preferably, the filtrate is washed to be clear with methanol.

[0041] Preferably, the washing with methanol is followed by the step of Soxhlet extraction.

[0042] Preferably, the solvent for Soxhlet extraction is tetrahydrofuran.

[0043] Preferably, the extraction time is 20-24 h, for example, it can be 21 h, 22 h, 23 h, 24 h, etc.

[0044] In the present application, the purpose of Soxhlet extraction is to remove residual solvent and catalyst and unreacted monomers.

[0045] Preferably, the drying temperature is 70-80°C, for example, it can be 72°C, 74°C, 76°C, 78°C, etc.

[0046] Preferably, the drying time is 20-25 h, for example, it can be 21 h, 22 h, 23 h, 24 h, etc.

[0047] Preferably, the drying is performed in a vacuum drying oven.

[0048] As a preferred technical solution of the present application, the preparation method comprises the following steps:

[0049] In the presence of a protective atmosphere, the phenolic monomer-containing and solvent are mixed, a catalyst is added at 0℃, and the mixture is reacted with 0.4-1.2 mol / L of phosphorus oxychloride for 30-40 min, and then refluxed at 80-90℃ for 15-24 h to obtain the rare earth ion adsorbent.

[0050] In a third aspect, the present application provides a use of the rare earth ion adsorbent according to the first aspect in selective adsorption and separation of rare earth ions.

[0051] In a fourth aspect, the present application provides a method for adsorption and separation of rare earth ions, which comprises the following steps:

[0052] The polyphosphate adsorbent according to the first aspect is mixed with a metal salt solution, and the metal salt solution comprises any one of a neodymium nitrate solution, a dysprosium nitrate solution, or a yttrium nitrate solution, and then adsorption and separation is performed.

[0053] Preferably, the mixed metal salt solution further comprises any one of iron nitrate, aluminum nitrate, calcium nitrate, magnesium nitrate, or a combination of at least two thereof.

[0054] Preferably, the mixing is performed under acidic conditions.

[0055] Preferably, the pH of the mixed solution is 2-7, for example, it can be 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8, 5, 5.2, 5.4, 5.6, 5.8, 6, 6.2, 6.4, 6.6, 6.8, etc.

[0056] In the present application, the acidic conditions are achieved by adding nitric acid, when the concentration of HNO3 is 0.1 mol / L, that is, under the condition of pH=1, the adsorption amount of all adsorbents to rare earth ions sharply decreases, because the hydroxyl group of the phosphate ester is difficult to be deprotonated, so the concentration of HNO3 needs to be less than 0.1 mol / L to promote the deprotonation of the hydroxyl group in the phosphate ester, and the optimal pH is 3-4.

[0057] Preferably, the mixing time is 20-25 h, for example, it can be 21 h, 22 h, 23 h, 24 h, etc.

[0058] Preferably, the mass ratio of the rare earth nitrate to the adsorbent is (0.0025-0.4):1, for example, it can be 0.005:1, 0.025:1, 0.045:1, 0.065:1, 0.085:1, 0.105:1, 0.125:1, 0.145:1, 0.165:1, 0.185:1, 0.205:1, 0.225:1, 0.245:1, 0.265:1, 0.285:1, 0.305:1, 0.325:1, 0.345:1, 0.365:1, 0.385:1, etc.

[0059] In the present application, the mixing is performed in a constant-temperature rotary shaker.

[0060] Preferably, the temperature of the constant-temperature rotary shaker is 24-27℃, for example, it can be 24℃, 25℃, 26℃, 27℃.

[0061] Preferably, the rotation speed of the constant-temperature rotary shaker is 160-230rpm, for example, it can be 170rpm, 180rpm, 190rpm, 200rpm, 210rpm, 220rpm, etc.

[0062] The numerical range in the present application not only includes the point values exemplified above, but also includes any point values between the above numerical ranges which are not listed, and the present application does not list the specific point values included in the range for the sake of brevity and simplicity.

[0063] Compared with the prior art, the present application has the following beneficial effects:

[0064] The rare earth ion adsorbent provided by the present application has high selectivity, high adsorption capacity, and excellent desorption and recycling performance for the polymer formed by the specific phosphate cross-linking; the K d values of the rare earth ion adsorbent for the rare earth ions and magnesium ions and calcium ions are all in the order of 10 5 mL / g, the separation factor for aluminum ions is ≥1.8, and the recycling retention rate is ≥87%, the rare earth ion adsorbent has strong chemical stability, low cost, simple synthesis operation, adjustable pore size, and good recycling and mechanical properties, so it has wide application prospects in the adsorption of rare earth materials. BRIEF DESCRIPTION OF DRAWINGS

[0065] Figure 1A The infrared spectrum of the rare earth ion adsorbent provided for Example 1 of the present application is shown in the figure;

[0066] Figure 1B The infrared spectrum of the rare earth ion adsorbent provided for Example 3 of the present application is shown in the figure;

[0067] Figure 2Scanning electron microscope images of the rare earth ion adsorbent provided in Example 1 and Example 3 of the present application, wherein a figure is the adsorbent of Example 1, b figure is the adsorbent of Example 3;

[0068] Figure 3A Nitrogen adsorption-desorption isotherm graph of the rare earth ion adsorbent provided in Example 3 of the present application;

[0069] Figure 3B Pore size distribution graph of the rare earth ion adsorbent provided in Example 3 of the present application;

[0070] Figure 4 Solid nuclear magnetic resonance spectrum of the rare earth ion adsorbent provided in Example 1 and Example 3 of the present application, wherein a figure and c figure are nuclear magnetic carbon spectrum of the adsorbent of Example 1 and Example 3 respectively, b figure and d figure are nuclear magnetic phosphorus spectrum of the adsorbent of Example 1 and Example 3 respectively;

[0071] Figure 5 Structure schematic diagram of the rare earth ion adsorbent provided in Example 1-4 of the present application, wherein a figure is the adsorbent of Example 1, b figure is the adsorbent of Example 2, c figure is the adsorbent of Example 3, d figure is the adsorbent of Example 4;

[0072] Figure 6 Adsorption performance of the rare earth ion adsorbent provided in Example 3 on Nd 3+ , Dy 3+ , Y 3+ and pH;

[0073] Figure 7 Adsorption performance of the rare earth ion adsorbent provided in Example 3 on Nd 3+ , Dy 3+ , Y 3+ and time;

[0074] Figure 8A Adsorption capacity of the rare earth ion adsorbent provided in Example 3 on Nd 3+ , Dy 3+ , Y 3+ and initial ion concentration;

[0075] Figure 8B Adsorption capacity of the rare earth ion adsorbent provided in Example 3 on Nd 3+ , Dy 3+ , Y 3+ and equilibrium concentration and related fitting curve;

[0076] Figure 9A Adsorption capacity of the rare earth ion adsorbent provided in Example 3 on Nd 3+ : Me n+Adsorption capacity chart of the adsorbent for metal ions in 1:1 (mole) solution;

[0077] Figure 9B Adsorption rate of the rare earth ion adsorbent provided in Example 3 for rare earth ions and impurity ions in actual rare earth leaching tail liquid; 3+ :Me n+ Adsorption capacity chart of the adsorbent for metal ions in 1:5 (mole) solution;

[0078] Figure 9C Adsorption rate of the rare earth ion adsorbent provided in Example 3 for rare earth ions and impurity ions in actual rare earth leaching tail liquid; 3+ :Me n+ Adsorption capacity chart of the adsorbent for metal ions in 1:10 (mole) solution;

[0079] Figure 10 Adsorption rate of the rare earth ion adsorbent provided in Example 3 for rare earth ions and impurity ions in actual rare earth leaching tail liquid;

[0080] Figure 11 Physical picture of the rare earth ion adsorbent provided in Examples 1-3 (black background). DETAILED DESCRIPTION

[0081] The technical solutions of the present application will be further described below in combination with the drawings and through specific embodiments. It should be understood by those skilled in the art that the embodiments are only used to help understand the present application and should not be regarded as specific limitations to the present application.

[0082] Example 1

[0083] The present embodiment provides a rare earth ion adsorbent, raw materials of the rare earth ion adsorbent are phosphorus oxychloride and hydroquinone, and the pore size of the rare earth ion adsorbent is 3.65 nm.

[0084] The present embodiment provides a preparation method of the rare earth ion adsorbent, and the specific steps include:

[0085] Under strict water-free nitrogen atmosphere, hydroquinone (2 g, 18.18 mmol) was dissolved in 30 mL of anhydrous dichloromethane, anhydrous acetonitrile (4.6 g, 45.45 mmol) was added, and then phosphorus oxychloride (1.85 g, 12.12 mmol) was dissolved in 10 mL of anhydrous acetonitrile, which was slowly dropped into the solution at 0°C within 30 min, and then the temperature was raised to room temperature, and the reaction mixture was condensed and refluxed at 86°C for 24 h to obtain an insoluble yellow-white solid; then 2 mol / L hydrochloric acid was added to neutralize the excess triethylamine, and the filtrate was washed with ultrapure water until it was neutral, and then the separated solid product was further extracted with tetrahydrofuran for 24 h, and the residual solvent and catalyst and unreacted monomers were removed, and finally vacuum drying at 80°C for 24 h, grinding into fine powder to obtain the rare earth ion adsorbent (PPE-1), as shown in Figure 11 (a).

[0086] The three cross-linking sites of phosphorus oxychloride can be cross-linked with the two cross-linking sites of hydroquinone as a connecting bridge to form a chain or network porous polymer, as shown in Figure 5 (a).

[0087] Example 2:

[0088] The rare earth ion adsorbent provided in this example is prepared from phosphorus oxychloride and 4,4'-biphenol, and has a pore size of 4.8 nm.

[0089] The preparation method of the rare earth ion adsorbent provided in this example includes the following specific steps:

[0090] Under strict water-free nitrogen atmosphere, 4,4'-biphenol (2 g, 10.7 mmol) was dissolved in 40 mL of anhydrous acetonitrile, anhydrous triethylamine (2.72 g, 26.85 mmol) was added, and then phosphorus oxychloride (1.10 g, 7.20 mmol) was dissolved in 10 mL of anhydrous acetonitrile, which was slowly dropped into the solution at 0°C within 30 min, and then the temperature was raised to room temperature, and the reaction mixture was condensed and refluxed at 86°C for 24 h to obtain an insoluble yellow-white solid; then 2 mol / L hydrochloric acid was added to neutralize the excess triethylamine, and the filtrate was washed with ultrapure water until it was neutral, and then the separated solid product was further extracted with tetrahydrofuran for 24 h, and the residual solvent and catalyst and unreacted monomers were removed, and finally vacuum drying at 80°C for 24 h, grinding into fine powder to obtain the rare earth ion adsorbent (PPE-2), as shown in Figure 11 (b).

[0091] The three cross-linking sites of phosphorus oxychloride can be cross-linked with the two cross-linking sites of 4,4'-biphenol as a connecting bridge to form a chain or network porous polymer, as shown inFigure 5 Figure 2b shows a schematic diagram of the cross-linking reaction between the phosphorus trichloride and the phloroglucinol.

[0092] Example 3

[0093] The rare earth ion adsorbent provided in this example has a raw material of phosphorus trichloride and phloroglucinol, and a pore size of 5.85 nm.

[0094] The preparation method of the rare earth ion adsorbent provided in this example includes the following specific steps:

[0095] Under a strict water-free nitrogen atmosphere, the phloroglucinol (1.55 g, 12.43 mmol) was dissolved in 20 mL of anhydrous acetonitrile, and anhydrous triethylamine (4.49 g, 44.42 mmol) was added. Then, the phosphorus trichloride (1.89 g, 12.34 mmol) was dissolved in 10 mL of anhydrous acetonitrile, and the solution was slowly dropped into the solution at 0°C within 30 min. Then, the temperature was raised to room temperature, and the reaction mixture was condensed and refluxed at 86°C for 24 h to obtain an insoluble yellow-white solid. Then, the excess triethylamine was neutralized by adding 2 mol / L hydrochloric acid, and the filtrate was washed with ultrapure water until it was neutral. Subsequently, the separated solid product was further extracted with tetrahydrofuran by Soxhlet extraction for 24 h, and the residual solvent and catalyst as well as the unreacted monomer were removed. Finally, the product was dried at 80°C under vacuum for 24 h, ground into a fine powder, and the rare earth ion adsorbent (PPE-3) was obtained.

[0096] The phosphorus trichloride with three cross-linking sites can be cross-linked with the phloroglucinol with three cross-linking sites as a connecting bridge to form a chain-like or network-like porous polymer, and a partial schematic diagram is shown in Figure 2c. Figure 5 Figure 2c shows a schematic diagram of the cross-linking reaction between the phosphorus trichloride and the phloroglucinol.

[0097] The structure of the rare earth ion adsorbents provided in Example 1 and Example 3 was characterized by an infrared spectrometer (Germany Bruker, Tensor 27), and the results are shown in Figures 3a and 3b, respectively. Figure 1A and Figure 1B The characteristic peaks observed near 1608 cm-1 to 1458 cm-1 of the two adsorbents correspond to the C=C stretching vibration peaks of the benzene ring skeleton, and the stretching vibration peaks of -OH are weakened near 3265 cm-1 to 3213 cm-1. A new characteristic peak appears at 968 cm-1 and 1014 cm-1, which belongs to the P-O-R stretching vibration peak, proving that the cross-linking reaction of the material is successful. -1 to 1458 cm -1 The characteristic peaks observed near 1608 cm-1 to 1458 cm-1 of the two adsorbents correspond to the C=C stretching vibration peaks of the benzene ring skeleton, and the stretching vibration peaks of -OH are weakened near 3265 cm-1 to 3213 cm-1. A new characteristic peak appears at 968 cm-1 and 1014 cm-1, which belongs to the P-O-R stretching vibration peak, proving that the cross-linking reaction of the material is successful. -1 and 3213 cm -1 The characteristic peaks observed near 1608 cm-1 to 1458 cm-1 of the two adsorbents correspond to the C=C stretching vibration peaks of the benzene ring skeleton, and the stretching vibration peaks of -OH are weakened near 3265 cm-1 to 3213 cm-1. A new characteristic peak appears at 968 cm-1 and 1014 cm-1, which belongs to the P-O-R stretching vibration peak, proving that the cross-linking reaction of the material is successful. -1 and 1014 cm -1 The characteristic peaks observed near 1608 cm-1 to 1458 cm-1 of the two adsorbents correspond to the C=C stretching vibration peaks of the benzene ring skeleton, and the stretching vibration peaks of -OH are weakened near 3265 cm-1 to 3213 cm-1. A new characteristic peak appears at 968 cm-1 and 1014 cm-1, which belongs to the P-O-R stretching vibration peak, proving that the cross-linking reaction of the material is successful.

[0098] The morphology of the rare earth ion adsorbents provided in Example 1 and Example 3 was characterized by a scanning electron microscope (Britain Zeiss, Sigma 300), and the results are shown in Figures 4a and 4b, respectively.Figure 2 As shown in FIGS. 1(c) and 1(d), wherein FIG. 1(c) is a graph of the adsorbent described in Example 1, and FIG. 1(d) is a graph of the adsorbent described in Example 3. PPE-1 is mainly irregular block objects, with rough surfaces, and some of them have obvious smaller nanoscale small particles closely packed. PPE-3 is mainly irregular spherical particles, mostly showing closely packed grape-like twin spheres, with smooth surfaces and larger particles.

[0099] The nitrogen adsorption and desorption performance and pore size of the rare earth ion adsorbents provided in Examples 1 and 3 were characterized by using a physical adsorption instrument, and the results are shown in FIGS. 2(a) and 2(b). Figure 3A As can be seen from FIGS. 2(a) and 2(b), the N2 loading slowly increases with the relative pressure, proving that the material is suitable for N2 monolayer adsorption and the pore structure is relatively uniform and regular. Figure 3B As shown in FIGS. 2(c) and 2(d), the pore size of the material is concentrated between 2-8 nm, and the average pore size is about 2.7 nm, belonging to mesoporous materials. Figure 3A Figure 3B The structure of the rare earth ion adsorbents provided in Examples 1 and 3 was characterized by using a 500M solid-state nuclear magnetic resonance spectrometer, and the results are shown in FIGS. 3(a) and 3(b).

[0100] The dried rare earth ion adsorbent was placed on a black background paper for observation. After complete and thorough extraction, it was obviously observed that the original yellow color changed to pure white, and then it was placed in a glass bottle for storage. The results obtained by the above tests are shown in FIGS. 4(a) and 4(b). Figure 4

[0101] Example 4: Figure 11

[0102] The rare earth ion adsorbent provided in this example is prepared from phosphorus oxychloride and 1,3,5-tris(4-hydroxyphenyl)benzene, and has a pore size of 7.8 nm.

[0103] The preparation method of the rare earth ion adsorbent provided in this example includes the following specific steps:

[0104] The preparation method of the rare earth ion adsorbent provided in this example includes the following specific steps:

[0105] ​​​Dissolve 1,3,5-tris(4-hydroxyphenyl)benzene (0.5 g, 1.41 mmol) in 20 mL of anhydrous acetonitrile under a strict water-free nitrogen atmosphere, add anhydrous triethylamine (0.51 g, 5.03 mmol), then dissolve phosphorus oxychloride (0.216 g, 1.41 mmol) in 5 mL of anhydrous acetonitrile, slowly drop into the solution at 0°C within 30 min, then raise the temperature to room temperature, and condense the reaction mixture under reflux at 86°C for 24 h to obtain an insoluble yellow-white solid; then add 2 mol / L hydrochloric acid to neutralize the excess triethylamine, wash with ultrapure water until the filtrate is neutral, then further extract the separated solid product with tetrahydrofuran for 24 h, remove the residual solvent and catalyst and unreacted monomer, and finally dry at 80°C under vacuum for 24 h, grind into fine powder, and obtain the rare earth ion adsorbent (PPE-4).

[0106] The three cross-linking sites of phosphorus oxychloride can be cross-linked with the three cross-linking sites of 1,3,5-tris(4-hydroxyphenyl)benzene as a connecting bridge to form a chain or a network of porous polymers, as shown in the partial schematic view of Figure 5 d in the middle.

[0107] Example 5

[0108] This example provides a rare earth ion adsorbent, which is only different from Example 1 in that the concentration of phosphorus oxychloride in the preparation method is 0.5 mol / L, and other steps and parameters are the same as those of Example 1.

[0109] Example 6

[0110] This example provides a rare earth ion adsorbent, which is only different from Example 1 in that the concentration of phosphorus oxychloride in the preparation method is 0.8 mol / L, and other steps and parameters are the same as those of Example 1.

[0111] Example 7

[0112] This example provides a rare earth ion adsorbent, which is only different from Example 1 in that the concentration of phosphorus oxychloride in the preparation method is 1 mol / L, and other steps and parameters are the same as those of Example 1.

[0113] Example 8

[0114] This example provides a rare earth ion adsorbent, which is only different from Example 1 in that the concentration of phosphorus oxychloride in the preparation method is 1.2 mol / L, and other steps and parameters are the same as those of Example 1.

[0115] Example 9

[0116] The embodiment provides a rare earth ion adsorbent, which is different from the embodiment 3 only in that the concentration of phosphorus oxychloride in the preparation method is 0.5 mol / L, and other steps and parameters are the same as those of the embodiment 3.

[0117] Embodiment 10

[0118] The embodiment provides a rare earth ion adsorbent, which is different from the embodiment 3 only in that the concentration of phosphorus oxychloride in the preparation method is 0.8 mol / L, and other steps and parameters are the same as those of the embodiment 3.

[0119] Embodiment 11

[0120] The embodiment provides a rare earth ion adsorbent, which is different from the embodiment 3 only in that the concentration of phosphorus oxychloride in the preparation method is 1 mol / L, and other steps and parameters are the same as those of the embodiment 3.

[0121] Embodiment 12

[0122] The embodiment provides a rare earth ion adsorbent, which is different from the embodiment 3 only in that the concentration of phosphorus oxychloride in the preparation method is 1.2 mol / L, and other steps and parameters are the same as those of the embodiment 3.

[0123] Experimental example 1

[0124] A 200 ppm neodymium nitrate solution is configured, and the solution is adjusted into neodymium solutions with pH=1, pH=2, pH=3, pH=4, pH=5, pH=6, pH=7 by using 0.1 mol / L HNO3 and 0.1 mol / L NaOH respectively, 0.005 g of the rare earth ion adsorbent provided in the embodiment 1, the embodiment 2 and the embodiment 3 is weighed in a 15 mL centrifuge tube, 10 mL of the neodymium nitrate solution is added, and the centrifuge tube is placed in a constant-temperature rotary shaker (25 DEG C, 200 rpm) to shake at constant temperature for 24 hours to reach adsorption equilibrium, after high-speed centrifugation, the supernatant is extracted by using a syringe, filtered by using a 0.22 um water filter head, and diluted by 4 times, and the neodymium ion concentration in the solution is determined by using an inductively coupled plasma optical emission spectrometer (ICP-OES), and the adsorption amount of the rare earth ion is calculated:

[0125]

[0126] Wherein C0 (mg / L) is the initial concentration of the rare earth ion, C e (mg / L) is the concentration of the rare earth ion in the solution at the adsorption equilibrium, V (L) is the solution volume, and m (g) is the mass of the added adsorbent; the results are shown in Table 1.

[0127] Table 1

[0128]

[0129] Results analysis: the experimental results are shown in Table 1, with the increase of the pH of the solution, the adsorption capacity of the adsorbent to Nd 3+ shows a trend of rapid increase and then tends to balance, and the optimal pH of the solution is 3, and the rare earth adsorbent of Example 3 is higher than that of Example 1 and Example 2, therefore, the adsorbent of Example 3 is selected as the test object in the performance test below, and the pH of the solution is 3.

[0130] Experimental example 2

[0131] Prepare 200 ppm of neodymium nitrate, dysprosium nitrate and yttrium nitrate solution respectively, and use 0.1 mol / L of HNO3 and 0.1 mol / L of NaOH to adjust the solution to pH=1, pH=2, pH=3, pH=4, pH=5, pH=6, pH=7 of rare earth solution respectively, weigh 0.005g, and put the rare earth ion adsorbent provided in Example 3 into a 15mL centrifuge tube, add 10mL of rare earth nitrate solution, and place it in a constant temperature rotary shaker (25℃, 200rpm) for constant temperature shaking for 24 hours to reach adsorption equilibrium, then centrifuge at high speed, use a syringe to suck the supernatant, filter with a 0.22mm water filter head, dilute 4 times, and use an inductively coupled plasma emission spectrometer (ICP-OES) to measure the concentration of rare earth ions in the solution, and calculate the adsorption capacity of rare earth ions.

[0132] Results analysis: as Figure 6 can be seen, the adsorbent has a wide pH range of use, has a strong and stable interaction with rare earth ions at pH=2-7, and the adsorption performance decreases when the adsorption site is protonated at pH=1.

[0133] Experimental example 3

[0134] Prepare 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, 550 ppm of neodymium nitrate, dysprosium nitrate and yttrium nitrate solution respectively, and use 0.1 mol / L of HNO3 to adjust the pH of the solution to 3, weigh 0.005g, and put the rare earth ion adsorbent provided in Example 3 into a 15mL centrifuge tube, add 10mL of rare earth nitrate solution, and place it in a constant temperature rotary shaker (25℃, 200rpm) for constant temperature shaking for 24 hours to reach adsorption equilibrium, then centrifuge at high speed, use a syringe to suck the supernatant, filter with a 0.22mm water filter head, dilute 4 times, and use an inductively coupled plasma emission spectrometer (ICP-AES) to measure the concentration of rare earth ions in the solution, and calculate the adsorption capacity of rare earth ions and fit the Langmuir and Freundlich isothermal adsorption model:

[0135] Langmuir: Qe=QMax ×K L ×C e / (1+K L ×C e )

[0136] Freundlich:

[0137] where Qe(mg / g) is the equilibrium adsorption capacity per unit mass of adsorbent; C e (mg / L) is the concentration of metal ions in the solution at adsorption equilibrium, Q Max (mg / L) is the fitted maximum adsorption capacity, K L , K F are Langmuir, Freundlich model constants, respectively, and n is the adsorption constant (adsorption strength).

[0138] Results analysis: As Figure 8A and Figure 8B can be seen, the adsorption process is more in line with the Langmuir adsorption model, proving that the adsorbent material is monolayer adsorption for rare earth ions, and the adsorption sites are uniformly distributed on the surface of the adsorbent, with a maximum fitted adsorption capacity of 225 mg / g.

[0139] Experimental Example 4

[0140] Prepare 200 ppm neodymium nitrate, dysprosium nitrate, and yttrium nitrate solutions, respectively, and adjust the pH of the rare earth solution to 3 with 0.1 mol / L HNO3 solution. Weigh 0.005 g of the rare earth ion adsorbent provided in Example 3 into a 15 mL centrifuge tube, add 10 mL of the rare earth nitrate solution, and place it in a constant temperature rotary shaker (25°C, 200 rpm) for 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140 min, respectively. Then take out the supernatant with a syringe, and use inductively coupled plasma atomic emission spectrometry (ICP-AES) to determine the concentration of rare earth ions in the solution, calculate the adsorption capacity of rare earth ions, and use pseudo-first-order kinetics and pseudo-second-order kinetics for fitting:

[0141] Pseudo-first-order kinetics:

[0142] Pseudo-second-order kinetics: Q t = K2 x Q e 2 x t / (1 + K2 x Q e x t)

[0143] where Q t (mg / g) is the adsorption capacity at time t; Q e(mg / g) is the equilibrium adsorption capacity of per unit mass of adsorbent, t is the adsorption time, K1 and K2 are the pseudo-first-order adsorption constant and the pseudo-second-order adsorption constant, respectively.

[0144] Result analysis: as Figure 7 It can be seen that the adsorption process is more in line with the pseudo-second-order kinetics model, which proves that the adsorption process of the adsorbent belongs to chemical adsorption, and the adsorption equilibrium is reached at 140 min.

[0145] Experimental example 5

[0146] 0.01g of the rare earth ion adsorbent provided in Example 3 was weighed into a 60mL centrifuge tube, 50mL of pH=3 neodymium nitrate solution containing interfering ions was added, and it was placed in a constant temperature rotary shaker (25℃, 200rpm) for constant temperature shaking for 24 hours to reach adsorption equilibrium. After high-speed centrifugation, the supernatant was sucked with a syringe, filtered with a water system filter head of 0.22mm, the concentration of rare earth ions in the solution was determined by ICP-OES, and the adsorption capacity of rare earth ions, the equilibrium distribution coefficient and the separation factor were calculated:

[0147] Equilibrium distribution coefficient

[0148] Separation factor

[0149] Wherein, C0(mg / L) is the initial concentration of metal ions, Ce(mg / L) is the concentration of metal ions in the solution at adsorption equilibrium, V(L) is the volume of the solution, and m(g) is the mass of the adsorbent added; is the equilibrium distribution coefficient of rare earth ions, is the equilibrium distribution coefficient of rare earth ions;

[0150] In the present application, when the interfering ion is iron ion, mixed solutions with neodymium-iron ion molar ratios of 1:1, 1:5 and 1:10 are prepared, and the separation factors at three concentrations are calculated;

[0151] When the interfering ion is aluminum ion, mixed solutions with neodymium-aluminum ion molar ratios of 1:1, 1:5 and 1:10 are prepared, and the separation factors at three concentrations are calculated;

[0152] When the interfering ion is magnesium ion, mixed solutions with neodymium-magnesium ion molar ratios of 1:1, 1:5 and 1:10 are prepared, and the separation factors at three concentrations are calculated;

[0153] When the interfering ion is calcium ion, mixed solutions with neodymium-calcium ion molar ratios of 1:1, 1:5 and 1:10 are prepared, and the separation factors at three concentrations are calculated;

[0154] Table 2

[0155]

[0156] Results analysis: from the above table and Figure 9A- Figure 9C It can be seen that the rare earth ion adsorbent provided by the application has high selectivity and high adsorption capacity for rare earth ions, and has fast adsorption rate and high efficiency. The rare earth ion adsorbent described in Example 3 has high selectivity for rare earth ions in the presence of divalent metal impurities.

[0157] Experimental example 6

[0158] Take 125mg of the rare earth ion adsorbent provided in Example 3 into a 100mL centrifuge tube, add 50mL of actual industrial wastewater, and place it in a constant temperature rotary shaker (25℃, 200rpm) for constant temperature shaking for 24 hours to reach adsorption equilibrium. After high-speed centrifugation, the supernatant is taken with a syringe and filtered with a 0.22μm water filter. The concentration of rare earth ions in the solution is determined by ICP-AES, and the adsorption rate of rare earth ions and the removal rate of impurity ions are calculated:

[0159]

[0160] Wherein, C0 is the initial metal ion concentration in the actual industrial wastewater, C e is the equilibrium concentration of metal ions in the wastewater after adsorption.

[0161] Results analysis: as Figure 10 shown, in the actual industrial wastewater, the material has high removal rate and good selectivity for rare earth, and the adsorption rate of rare earth ions reaches 96.3% when the solid-liquid ratio is 2.5g / L. The adsorption rate of Al 3+ is lower than that of rare earth ions, and the adsorption rate of other metal ions is much lower than that of rare earth ions.

[0162] In summary, the rare earth ion adsorbent provided by the application forms a phosphonate-linked porous organic adsorbent by polymerization of phosphorus oxychloride and phenolic monomers, which realizes high selectivity and high adsorption capacity for rare earth ions, and has excellent desorption and recycling performance. Moreover, no crosslinking agent is needed, the preparation method is simple, cost-saving and environmentally friendly.

[0163] The applicant declares that the polyphosphonate rare earth ion adsorbent and its preparation method and application of the application are illustrated by the above examples, but the application is not limited to the above examples, i.e. it does not mean that the application must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvement of the application, equivalent replacement of the raw materials selected by the application, addition of auxiliary ingredients, selection of specific methods, etc. fall within the scope of protection and disclosure of the application.

Claims

1. Use of a polyphosphate rare earth ion adsorbent for the selective adsorption separation of rare earth ions, characterized in that, The polyphosphate rare earth ion adsorbent comprises a porous organic polymer of phosphate functional groups having a structure of Formula I or Formula II: Formula I; Formula II; wherein R is a benzene ring; The polyphosphate rare earth ion adsorbent is a porous organic polymer having a chain and a network formed by a phosphorus oxychloride monomer and a phenol monomer; The rare earth ion adsorbent has a pore size of 2-7 nm.

2. Use according to claim 1, characterized in that, The preparation method of the polyphosphate rare earth ion adsorbent comprises the following steps: The phosphorus oxychloride monomer and the phenol monomer are reacted under alkaline conditions at 0°C to obtain the rare earth ion adsorbent.

3. Use according to claim 2, characterized in that, The reaction is performed in the presence of a catalyst.

4. Use according to claim 3, characterized in that, The molar ratio of the catalyst to the phosphorus oxychloride is (3-4):

1.

5. Use according to claim 3, characterized in that, The catalyst comprises anhydrous triethylamine.

6. Use according to claim 2, characterized in that, The reaction is performed in a solvent, and the solvent comprises dichloromethane or acetonitrile.

7. Use according to claim 2, characterized in that, The initial concentration of the phosphorus oxychloride is 0.4-1.2 mol / L.

8. Use according to claim 2, characterized in that, The reaction is performed in the presence of a protective atmosphere.

9. Use according to claim 8, characterized in that, The protective atmosphere comprises nitrogen or argon.

10. The use according to claim 2, characterized in that, The reaction comprises a polymerization stage and a reflux stage.

11. Use according to claim 10, characterized in that, The reaction temperature of the polymerization stage is 0°C.

12. The use according to claim 10, characterized in that, The reaction time of the polymerization stage is 30-40 min.

13. The use according to claim 10, characterized in that, The reaction temperature of the reflux stage is 80-90°C.

14. The use according to claim 10, characterized in that, The reaction time of the reflux stage is 15-24 h.

15. The use according to claim 2, characterized in that, The preparation method comprises the following steps: In the presence of a protective atmosphere, the phenol monomer-containing solution is mixed with a solvent, a catalyst is added at 0°C, and the mixture is reacted with 0.4-1.2 mol / L of phosphorus oxychloride for 30-40 min, and then refluxed at 80-90°C for 15-24 h to obtain the rare earth ion adsorbent.

16. The use according to claim 1, characterized in that, The adsorption and separation comprises the following steps: The polyphosphate rare earth ion adsorbent is mixed with a metal salt solution, and the metal salt solution comprises any one of a neodymium nitrate solution, a dysprosium nitrate solution, or a yttrium nitrate solution, and the mixture is subjected to adsorption and separation.

17. Use according to claim 16, characterized in that, The metal salt solution further comprises any one of iron nitrate, aluminum nitrate, calcium nitrate, magnesium nitrate, or a combination of at least two thereof.

18. The use according to claim 16, characterized in that, The pH of the mixed solution is 2-7.

19. The use according to claim 16, characterized in that, The mixing time is 20-25 h.

20. The use according to claim 16, characterized in that, The mixing is performed in a constant-temperature rotary shaker.

21. The use according to claim 20, characterized in that, The temperature of the constant-temperature rotary shaker is 24-27°C.

22. The use according to claim 20, characterized in that, The rotation speed of the constant-temperature rotary shaker is 160-230 rpm.

Images