Phosphate ester compound and method for extracting metal ions

Abstract

The chemical structure of the phosphate compound is as follows: # imgabs0 #, wherein R1 is H or C1-10 alkyl; r2 is alkyl with 1 to 10 carbon atoms; z is-N (R3) (R4) or-O (R3), where R3 is a C1-10 alkyl group, and R4 is H or a C1-10 alkyl group. The phosphate ester compound can be used for extracting metal ions, and when Z is-N (R3) (R4), the total carbon number of R1 and R2 is greater than or equal to 6; when Z is-O (R3), the total carbon number of R1 and R2 is greater than or equal to 4.

Description

Technical Field

[0001] The present disclosure relates to phosphate ester compounds, and more particularly to methods for extracting metal ions using phosphate ester compounds. Background Art

[0002] Rare earth elements are widely used, mainly in various functional materials, including permanent magnets, polishing, catalysis, hydrogen storage, etc. However, there is a problem of wastewater discharge in the rare earth purification production process. Each ton of rare earth oxide is accompanied by about 50 tons of ammonia nitrogen / saponification wastewater, which cannot be discharged directly and has high treatment costs. In addition, praseodymium (Pr) and neodymium (Nd) in rare earth metals have similar electron orbitals and ion radii, making them difficult to extract and separate, and the existing extractants have poor Nd ion / Pr ion selectivity.

[0003] In summary, there is an urgent need for alkaline extractants with high Nd ion / Pr ion selectivity and reduced saponification to reduce the number of extractions and reduce the amount of wastewater and ammonia nitrogen emissions. Summary of the invention

[0004] An embodiment of the present disclosure provides a phosphate compound, the chemical structure of which is as follows: Where R 1 H or C 1-10 Alkyl; R 2 C 1-10 alkyl; Z is -N(R 3 )(R 4 ) or -O(R 3 ), where R 3 C 1-10 The alkyl group, and R 4 H or C 1-10 When Z is -N(R 3 )(R 4 ), R 1 and R 2 The total carbon number is greater than or equal to 6; when Z is -O(R 3 ), R 1 and R 2 The total carbon number is greater than or equal to 4.

[0005] An embodiment of the present disclosure provides a method for extracting metal ions, comprising: mixing an aqueous solution containing metal ions with an extract containing the above-mentioned phosphate compound to form a mixture; and allowing the mixture to stand to separate into an aqueous layer and an organic layer, and collecting the organic layer, wherein the organic layer includes the phosphate compound and the metal ions. DETAILED DESCRIPTION

[0006] An embodiment of the present disclosure provides a phosphate compound, the chemical structure of which is as follows: Where R1 H or C 1-10 Alkyl; R 2 C 1-10 alkyl; Z is -N(R 3 )(R 4 ) or -O(R 3 ), where R 3 C 1-10 The alkyl group, and R 4 H or C 1-10 When Z is -N(R 3 )(R 4 ), R 1 and R 2 The total carbon number is greater than or equal to 6; when Z is -O(R 3 ), R 1 and R 2 The total carbon number of R is greater than or equal to 4. 1 and R 2 If the total carbon number of Z is too small, the phosphate compound is easily miscible with water and cannot be used as an extractant. 2 or -OH (ie R 3 and R 4 If R 1 , R 2 , R 3 , or R 4 If the carbon number is too large, there will be no obvious advantages but further increase the cost.

[0007] In some embodiments, the chemical structure of the phosphate compound is

[0008]

[0009] In some embodiments, the synthesis method of the phosphate compound can be to take bis (2-ethylhexyl) phosphite, diamine or alkoxyamine (H 2 NC 2 H 4 -Z, Z is -N(R 3 )(R 4 ) or -O(R 3 )), and ketones or aldehydes (R 1 -(C=O)-R 2 ) after reaction, a hydrolysis reaction is performed to form a phosphate ester. The above reaction is as follows: It is to be understood that the above reaction is only used for illustration and does not limit the embodiments of the present disclosure. A person skilled in the art can synthesize the above phosphate compound in any manner, without being limited to the above synthesis method.

[0010] An embodiment of the present disclosure provides a method for extracting metal ions, comprising: mixing an acidic aqueous solution containing metal ions with an extract containing the above-mentioned phosphate compound to form a mixture.

[0011] In some embodiments, the metal ions include ions of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, or a combination thereof. In addition to the above rare earth metal ions, the metal ions may also be other metal ions, such as ions of Fe, Co, Ni, Li, Mn, or a combination thereof. In some embodiments, the metal ions include Pr ions and Nd ions, and the extraction efficiency of the extract for Nd ions is higher than the extraction efficiency for Pr ions. For example, the selectivity of Nd ions / Pr ions of the extract may exceed 1.1 or 1.2, or even exceed 1.5. In some embodiments, the metal ions may be ions of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, Fe, Co, Ni, Li, Mn, or a combination thereof.

[0012] In some embodiments, the extract further includes a diluent, and the diluent includes sulfonated kerosene, aviation kerosene, heptane, octane, or a combination thereof. The weight ratio of the phosphate compound to the diluent may be 1:5 to 5:1. If the ratio of the diluent is too high, the extraction effect of the extract is reduced.

[0013] In some embodiments, the pH value of the mixture is 1 to 3. Since the phosphate compound in the extract is an alkaline extractant, the mixture of the extract and the acidic aqueous solution does not need to add alkali to make the pH value of the mixture reach the above range. In other words, the phosphate compound of the present disclosure can reduce or eliminate the need for the saponification (addition of alkali) step commonly seen in conventional extraction steps. On the other hand, the pH value of the above mixture may be high and acid needs to be added to reach a pH value of 1 to 3. However, the acid is originally present in the acidic aqueous solution, so the addition of the acid does not require an additional treatment step (compared to the saponification step).

[0014] In some embodiments, the extract further includes an acidic extractant or a neutral extractant to match the aforementioned phosphate compound (alkaline extractant). In these embodiments, the molar ratio of the phosphate compound to the acidic extractant (or neutral extractant) is 1:9 to 9:1. If the ratio of the acidic extractant or the neutral extractant is too high, the selectivity of Nd ions / Pr ions in the extract is reduced. In some embodiments, the acidic extractant can be commercially available P507 (purchased from Seedchem, its structure is ), P204 (purchased from Sigma-Aldrich, its structure is ), Bis(2,4,4-trimethylpentyl)phosphinic acid (Bis(2,4,4-trimethylpentyl)phosphinic acid, purchased from Sigma-Aldrich, and its structure is ), or a combination thereof. In some embodiments, the neutral extractant may be bis(2-ethylhexyl)phosphite (Bis(2-ethylhexyl)phosphite, purchased from Sigma-Aldrich, having a structure of ), TBP (purchased from Alfa Aesar, its structure is ), or a combination of the above.

[0015] In some embodiments, the metal ion concentration of the acidic aqueous solution is 0.001 mol / L to 2.0 mol / L. If the metal ion concentration is too low, the selectivity between metal ions (such as Nd ions / Pr ions) is reduced. If the metal ion concentration is too high, the extractant is easily saturated, resulting in emulsification and difficulty in stratification.

[0016] In some embodiments, the acid in the acidic aqueous solution includes hydrochloric acid, nitric acid, sulfuric acid, or a combination thereof.

[0017] In some embodiments, the above method further allows the mixture to stand to separate into an aqueous layer and an organic layer, and collects the organic layer. The organic layer includes a phosphate compound and metal ions. The metal ions in the organic layer can then be stripped by a high concentration (e.g., 3M to 6M) of an inorganic acid such as hydrochloric acid, and the extract can be used for extraction again.

[0018] It is worth noting that the above-mentioned phosphate compounds can be used not only for extracting metal ions such as separating Nd ions and Pr ions, but also as anti-corrosion agents in the electronics industry, lubricants for aluminum frame forging, or other applications.

[0019] In order to make the above contents and other purposes, features, and advantages of the present disclosure more clearly understood, embodiments are given below for detailed description as follows:

[0020] Example

[0021] Synthesis example 1

[0022] After mixing bis(2-ethylhexyl)phosphite (20mmol), N,N-dimethylethylenediamine (22mmol), octanal (22mmol), 16mL of anhydrous toluene, and 50mg of p-toluenesulfonic acid, the mixture was heated to 130°C and stirred for 6 hours. Then, 200mg of calcium carbonate was added to the crude product after the reaction, and the reaction was refluxed and stirred for 15 minutes to remove the catalyst p-toluenesulfonic acid. After cooling to room temperature, the mixture was washed with 20mL of deionized water for 3 times, and the organic layer was collected and the solvent was removed by vacuum distillation to obtain an intermediate product. 4mL of 5M KOH solution, 12mL of anhydrous ethanol, and 0.032g of KI catalyst were added to the intermediate product, heated to 90°C and stirred for 10 hours to perform a hydrolysis reaction. After the reaction was completed, the solvent was removed by vacuum distillation, and the product was dissolved with an appropriate amount of n-heptane. Impurities were removed by washing with deionized water. Water was added to the organic phase, and the organic phase was acidified with HCl solution to pH <1. Continuously wash with deionized water until the organic phase is free of chloride, remove the solvent under reduced pressure and dry to obtain the product. The hydrogen spectrum of the product is as follows: 1 HNMR (400MHz, CDCl 3 )δ:0.89(t,9H,CH 3 ),1.12-1.38(m,20H,CH 2 ),1.41-1.52(br,1H,CH),1.70-1.92(br,1H,CH),2.75-3.02(s,6H,CH 3 ),3.20(br,2H,CH 2 ),3.45(br,2H,CH 2 ),3.55-3.90(br,2H,CH 2 ),8.25(s,1H,OH). The mass spectrum of the product is as follows: LS-MS(m / z):[M+1] + =393.3. The chemical structure of the above product is

[0023] Synthesis example 2

[0024] After mixing bis(2-ethylhexyl)phosphite (20 mmol), N-ethylethylenediamine (22 mmol), decanal (22 mmol), 16 mL of anhydrous toluene, and 50 mg of p-toluenesulfonic acid, the remaining synthesis steps are similar to those of Synthesis Example 1. The hydrogen spectrum of the product is as follows: 1 H NMR (400 MHz, CDCl 3 )δ:0.85(t,12H,CH 3 ),1.02-1.54(m,22H,CH 2),1.54-1.65(br,1H,CH),1.65-1.79(br,1H,CH),2.45-2.82(br,6H,CH 2 ),2.92(s,1H,OH),3.58-3.75(m,2H,CH 2 ). The mass spectrum of the product is as follows: LS-MS (m / z): [M+1] + =393.3. The chemical structure of the above product is

[0025]

[0026] Synthesis example 3

[0027] After mixing bis(2-ethylhexyl)phosphite (20 mmol), 2-methoxyethylamine (22 mmol), octanal (22 mmol), 16 mL of anhydrous toluene, and 50 mg of p-toluenesulfonic acid, the remaining synthesis steps are similar to those of Synthesis Example 1. The hydrogen spectrum of the product is as follows: 1 H NMR (400 MHz, CDCl 3 )δ:0.86(t,9H,CH 3 ),1.12-1.58(m,20H,CH 2 ),1.65-1.80(br,1H,CH),1.87-1.99(br,1H,CH),2.79-3.25(dd,2H,CH 2 ),3.30(s,1H,OH),3.34(s,3H,CH 3 ),3.65-3.75(m,2H,CH 2 ),3.75-3.87(m,2H,CH 2 ). The mass spectrum of the product is as follows: LS-MS (m / z): [MH] = 378.3.

[0028] The chemical structure of the above product is

[0029] Synthesis example 4

[0030] After mixing bis(2-ethylhexyl)phosphite (20 mmol), 2-methoxyethylamine (22 mmol), decanal (22 mmol), 16 mL of anhydrous toluene, and 50 mg of p-toluenesulfonic acid, the remaining synthesis steps are similar to those of Synthesis Example 1. The hydrogen spectrum of the product is as follows: 1 H NMR (400 MHz, CDCl 3 )δ:0.88(t,9H,CH 3 ),1.11-1.60(m,24H,CH 2),1.60-1.82(br,1H,CH),1.82-1.96(br,1H,CH),2.78-2.90(br,2H,CH 2 ),3.33(s,1H,OH),3.52(s,3H,CH 3 ),3.56-3.87(m,2H,CH 2 ),3.87-4.02(m,2H,CH 2 ). The mass spectrum of the product is as follows: LS-MS (m / z): [MH] = 406.3.

[0031] The chemical structure of the above product is

[0032]

[0033] Synthesis example 5

[0034] After mixing bis(2-ethylhexyl)phosphite (20 mmol), 2-methoxyethylamine (22 mmol), 3-pentanone (22 mmol), 16 mL of anhydrous toluene, and 50 mg of p-toluenesulfonic acid, the remaining synthesis steps are similar to those of Synthesis Example 1. The hydrogen spectrum of the product is as follows: 1 H NMR (400 MHz, CDCl 3 )δ:0.80-0.94(m,12H,CH 3 ),1.17-1.44(m,10H,CH 2 ),1.45-1.53(m,1H,CH),3.53(s,3H,CH 3 ),3.57-3.72(m,4H,CH 2 ),3.77-3.87(m,2H,CH 2 ), 6.09 (s, 1H, OH). The mass spectrum of the product is as follows: LS-MS m / z: [MH] = 336.2. The chemical structure of the above product is

[0035] Comparative Example 1

[0036] Take 0.5g of praseodymium-neodymium carbonate (Pr:Nd molar ratio is 25:75) and dissolve it in 0.1M hydrochloric acid (10mL). Stir for 5 minutes to form an acidic aqueous solution and pour it into the extraction bottle. In addition, take 1 part by weight of acidic extractant P507 and 1 part by weight of kerosene to mix to form an extract. Pour 10mL of the extract into the extraction bottle and mix for 5 minutes, and add KOH to adjust the pH value of the mixed solution to 2 (the so-called saponification step). Then continue to stir the mixed solution for 30 minutes and let it stand to separate, and collect the upper organic layer. Use 4M hydrochloric acid aqueous solution (10mL) to extract the organic layer to analyze the Pr ions and Nd ions extracted from the organic layer. The extraction efficiency of Pr ions = extracted Pr ions / Pr ions in acidic aqueous solution. The extraction efficiency of Nd ions = extracted Nd ions / Nd ions in acidic aqueous solution. The extraction efficiency of Nd ions of the above extract is 90.9%, the extraction efficiency of Pr ions is 90.6%, and the selectivity of Nd ions / Pr ions is 1.04.

[0037] Example 1

[0038] Take 0.5g of praseodymium-neodymium carbonate (Pr:Nd molar ratio is 25:75) and dissolve it in 0.1M hydrochloric acid (10mL). Stir for 5 minutes to form an acidic aqueous solution and pour it into an extraction bottle. In addition, take 1 weight part of the product of Synthesis Example 1 as an extractant and 1 weight part of kerosene to mix to form an extract. Pour 10mL of the extract into the extraction bottle and mix for 5 minutes, and add hydrochloric acid to adjust the pH value of the mixed solution to 1. Then continue to stir the mixed solution for 30 minutes and let it stand to separate, and collect the upper organic layer. Use 4M hydrochloric acid aqueous solution (10mL) to extract the organic layer to analyze the Pr ions and Nd ions extracted in the organic layer. The extraction efficiency of Nd ions in the above extract is 4.7%, the extraction efficiency of Pr ions is 3.1%, and the selectivity of Nd ions / Pr ions is 1.54.

[0039] Example 2

[0040] Take 0.5g of praseodymium-neodymium carbonate (Pr:Nd molar ratio is 25:75) and dissolve it in 0.1M nitric acid (10mL). Stir for 5 minutes to form an acidic aqueous solution and pour it into an extraction bottle. In addition, take 1 mole of the product of Synthesis Example 1 and 1 mole of the acidic extractant P507 as the extractant, and take 1 weight part of the extractant and 1 weight part of kerosene to mix to form an extract. After pouring 10mL of the extract into the extraction bottle and stirring the mixture for 30 minutes, let it stand and separate, and collect the upper organic layer. Use 4M hydrochloric acid aqueous solution (10mL) to extract the organic layer to analyze the Pr ions and Nd ions extracted in the organic layer. The extraction efficiency of Nd ions in the above extract is 95.2%, the extraction efficiency of Pr ions is 94.6%, and the selectivity of Nd ions / Pr ions is 1.14.

[0041] Example 3

[0042] Take 0.5g of praseodymium-neodymium carbonate (Pr:Nd molar ratio is 25:75) and dissolve it in 0.1M nitric acid (10mL). Stir for 5 minutes to form an acidic aqueous solution and pour it into an extraction bottle. In addition, take 1 mole of the product of Synthesis Example 1 and 3 moles of acidic extractant P507 as an extractant, and take 1 weight part of the extractant and 1 weight part of kerosene to form an extract. Pour 10mL of the extract into the extraction bottle and mix for 5 minutes, and add nitric acid to adjust the pH value of the mixed solution to 2. Then continue to stir the mixed solution for 30 minutes and then let it stand for stratification, and collect the upper organic layer. Use 4M hydrochloric acid aqueous solution (10mL) to extract the organic layer to analyze the Pr ions and Nd ions extracted in the organic layer. The extraction efficiency of Nd ions in the above extract is 97.5%, the extraction efficiency of Pr ions is 96.4%, and the selectivity of Nd ions / Pr ions is 1.47.

[0043] Example 4

[0044] Take 0.5g of praseodymium-neodymium carbonate (Pr:Nd molar ratio is 25:75) and dissolve it in 0.1M hydrochloric acid (10mL). Stir for 5 minutes to form an acidic aqueous solution and pour it into an extraction bottle. In addition, take 1 weight part of the product of Synthesis Example 3 as an extractant and 1 weight part of kerosene to mix to form an extract. Pour 10mL of the extract into the extraction bottle and mix for 5 minutes, and add hydrochloric acid to adjust the pH value of the mixed solution to 2.5. Then continue to stir the mixed solution for 30 minutes and let it stand to separate, and collect the upper organic layer. Use 4M hydrochloric acid aqueous solution (10mL) to extract the organic layer to analyze the Pr ions and Nd ions extracted in the organic layer. The extraction efficiency of Nd ions in the above extract is 40.5%, the extraction efficiency of Pr ions is 35.0%, and the selectivity of Nd ions / Pr ions is 1.26.

[0045] Example 5

[0046] Take 0.5g of praseodymium-neodymium carbonate (Pr:Nd molar ratio is 25:75) and dissolve it in 0.1M hydrochloric acid (10mL). Stir for 5 minutes to form an acidic aqueous solution and pour it into an extraction bottle. In addition, take 1 mole of the product of Synthesis Example 3 and 1 mole of the acidic extractant P507 as the extractant, and take 1 weight part of the extractant and 1 weight part of kerosene to mix to form an extract. After pouring 10mL of the extract into the extraction bottle and stirring the mixture for 30 minutes, let it stand and separate, and collect the upper organic layer. Use 4M hydrochloric acid aqueous solution (10mL) to extract the organic layer to analyze the Pr ions and Nd ions extracted in the organic layer. The extraction efficiency of Nd ions in the above extract is 83.1%, the extraction efficiency of Pr ions is 77.7%, and the selectivity of Nd ions / Pr ions is 1.41.

[0047] Example 6

[0048] Take 0.5g of praseodymium-neodymium carbonate (Pr:Nd molar ratio is 25:75) and dissolve it in 0.1M nitric acid (10mL). Stir for 5 minutes to form an acidic aqueous solution and pour it into an extraction bottle. In addition, take 1 mole of the product of Synthesis Example 3 and 1 mole of the acidic extractant P507 as the extractant, and take 1 weight part of the extractant and 1 weight part of kerosene to mix to form an extract. After pouring 10mL of the extract into the extraction bottle and stirring the mixed solution for 30 minutes, let it stand and separate, and collect the upper organic layer. Use 4M hydrochloric acid aqueous solution (10mL) to extract the organic layer to analyze the Pr ions and Nd ions extracted in the organic layer. The extraction efficiency of Nd ions in the above extract is 89.7%, the extraction efficiency of Pr ions is 87.7%, and the selectivity of Nd ions / Pr ions is 1.21.

[0049] Example 7

[0050] Take 0.5g of praseodymium-neodymium carbonate (Pr:Nd=25:75, mol:mol) and dissolve it in 0.1M nitric acid (10mL). Stir for 5 minutes to form an acidic aqueous solution and pour it into an extraction bottle. In addition, take 1 mole of the product of Synthesis Example 3 and 3 moles of the acidic extractant P507 as an extractant, and take 1 weight part of the extractant and 1 weight part of kerosene to mix to form an extract. Pour 10mL of the extract into the extraction bottle and mix for 5 minutes, and add nitric acid to adjust the pH value of the mixed solution to 2. Then continue to stir the mixed solution for 30 minutes and then let it stand to separate, and collect the upper organic layer. Use 4M hydrochloric acid aqueous solution (10mL) to extract the organic layer to analyze the Pr ions and Nd ions extracted in the organic layer. The extraction efficiency of Nd ions in the above extract is 97.0%, the extraction efficiency of Pr ions is 95.5%, and the selectivity of Nd ions / Pr ions is 1.55.

[0051] Example 8

[0052] Take 0.25g of dysprosium oxide (purity 99%) and dissolve it in 1M nitric acid (10mL). Stir for 5 minutes to form an acidic aqueous solution and pour it into an extraction bottle. In addition, take 1 weight part of the product of Synthesis Example 3 as an extractant and mix it with 1 weight part of kerosene to form an extract. Pour 10mL of the extract into the extraction bottle and mix for 5 minutes, and add 10% sodium hydroxide aqueous solution to adjust the pH value of the mixed solution to 2. Then continue to stir the mixed solution for 30 minutes and then let it stand to separate the layers, and collect the upper organic layer. Use 4M nitric acid aqueous solution (10mL) to back-extract the organic layer to analyze the Dy ions extracted in the organic layer. The extraction efficiency of Dy ions in the above extract is 84.9%.

[0053] Example 9

[0054] Take 0.5g of cobalt (purity 99.8%) and dissolve it in 1M nitric acid (10mL). Stir for 5 minutes to form an acidic aqueous solution and pour it into an extraction bottle. In addition, take 1 weight part of the product of Synthesis Example 4 as an extractant and mix it with 1 weight part of kerosene to form an extract. Pour 10mL of the extract into the extraction bottle and mix for 5 minutes, and add 10% sodium hydroxide aqueous solution to adjust the pH value of the mixed solution to 2. Then continue to stir the mixed solution for 30 minutes and then let it stand to separate the layers, and collect the upper organic layer. Use 4M nitric acid aqueous solution (10mL) to extract the organic layer to analyze the Co ions extracted in the organic layer. The extraction efficiency of Co ions in the above extract is 33.1%.

[0055] Example 10

[0056] Take 0.5g of cerium chloride (purity 99%) and dissolve it in 1M nitric acid (10mL). Stir for 5 minutes to form an acidic aqueous solution and pour it into an extraction bottle. In addition, take 1 weight part of the product of Synthesis Example 4 as an extractant and mix it with 1 weight part of kerosene to form an extract. Pour 10mL of the extract into the extraction bottle and mix for 5 minutes, and add 10% sodium hydroxide aqueous solution to adjust the pH value of the mixed solution to 2. Then continue to stir the mixed solution for 30 minutes and then let it stand to separate the layers, and collect the upper organic layer. Use 4M nitric acid aqueous solution (10mL) to extract the organic layer to analyze the Ce ions extracted in the organic layer. The extraction efficiency of Ce ions in the above extract is 18.8%.

[0057] Synthesis example 6

[0058] After mixing bis(2-ethylhexyl)phosphite (20 mmol), N,N-dimethylethylenediamine (22 mmol), 3-pentanone (22 mmol), 16 mL of anhydrous toluene, and 50 mg of p-toluenesulfonic acid, the remaining synthesis steps are similar to those of Synthesis Example 1. The hydrogen spectrum of the product is as follows: 1 H NMR (400 MHz, CDCl 3 )δ:0.81-0.93(m,12H,CH 3 ),1.19-1.43(m,10H,CH 2 ),1.40-1.56(m,1H,CH),2.71-3.05(m,6H,CH 3 ),3.57-3.72(m,4H,CH 2 ),3.77-3.87(m,2H,CH 2 ),7.83(s,1H,OH). The mass spectrum of the product is as follows: LS-MS m / z: [MH]=335.3. The chemical structure of the above product is

[0059] Comparative Example 2

[0060] Take 0.5g of praseodymium-neodymium carbonate (Pr:Nd molar ratio is 25:75) and dissolve it in 0.1M hydrochloric acid (10mL). Stir for 5 minutes to form an acidic aqueous solution and pour it into an extraction bottle. In addition, take 1 part by weight of the product of Synthesis Example 6 as an extractant and 1 part by weight of kerosene to form an extract. Pour 10mL of the extract into the extraction bottle and mix for 5 minutes, and add hydrochloric acid to adjust the pH value of the mixed solution to 1. Then continue to stir the mixed solution for 30 minutes, and the water layer becomes turbid, and it is still impossible to separate after standing for more than 1 day. The water layer contains a high concentration of phosphorus detected by ICP, and it is speculated that the phosphate compound of Synthesis Example 6 is miscible with water and cannot be used as an extractant.

[0061] Although the present disclosure has been disclosed in several embodiments as above, it is not intended to limit the present disclosure. Any person with ordinary knowledge in the technical field can make any changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be based on that defined in the attached claims.

Claims

1. Phosphate compounds, the chemical structure of which is as follows: in R 1 H or C 1-10 The alkyl group; R 2 C 1-10 The alkyl group; Z is -N(R 3 )(R 4 ) or -O(R 3 ), where R 3 C 1-10 The alkyl group of R 4 H or C 1-10 The alkyl group When Z is -N(R 3 )(R 4 ), R 1 and R 2 The total carbon number is greater than or equal to 6; When Z is -O(R 3 ), R 1 and R 2 The total carbon number is greater than or equal to 4.

2. The phosphate compound according to claim 1, wherein the chemical structure is 3. A method for extracting metal ions, comprising: mixing an acidic aqueous solution containing metal ions with an extract containing the phosphate compound of claim 1 to form a mixture; as well as The mixture was allowed to stand to separate into an aqueous layer and an organic layer, and the organic layer was collected. The organic layer includes the phosphate compound and metal ions.

4. The method for extracting metal ions as described in claim 3, wherein the metal ions include ions of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, Fe, Co, Ni, Li, Mn, or a combination thereof.

5. The method for extracting metal ions as claimed in claim 3, wherein the metal ions include Pr ions and Nd ions, and the extraction efficiency of the extracting solution for Nd ions is higher than that for Pr ions.

6. The method for extracting metal ions as claimed in claim 3, wherein the extract further comprises a diluent, and the diluent comprises sulfonated kerosene, aviation kerosene, heptane, octane, or a combination thereof, wherein the weight ratio of the phosphate compound to the diluent is 1:5 to 5:

1.

7. The method for extracting metal ions as claimed in claim 3, wherein the pH value of the mixture is 1 to 3.

8. The method for extracting metal ions according to claim 3, wherein the extracting solution further comprises an acidic extractant or a neutral extractant, and the molar ratio of the phosphate compound to the acidic extractant or the neutral extractant is 1:9 to 9:

1.

9. The method for extracting metal ions according to claim 3, wherein the metal ion concentration of the acidic aqueous solution is 0.001 mol / L to 2.0 mol / L.

10. The method for extracting metal ions according to claim 3, wherein the acid in the acidic aqueous solution comprises hydrochloric acid, nitric acid, sulfuric acid, or a combination thereof.

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