Method for removing metal ion impurities

Abstract

The invention discloses a method for removing metal ions in a chemical reagent, which comprises the following steps: dissolving the chemical reagent in a first solvent to prepare a mixed solution, adjusting to acidity, carrying out ion exchange through cation exchange resin, and then removing the first solvent. Compared with other methods for removing metal impurities, the method provided by the invention has the following advantages: the ion exchange resin does not pollute the compound; moreover, the removal effect of the ion exchange resin is better, the metal ions can be removed to 100 ppb or below, the overall metal ion removal rate exceeds 90%, and the method can be suitable for large-scale industrial production.

Description

Technical Field

[0001] The invention relates to a method for removing metal ions in a chemical reagent, and in particular to a method for removing metal ions with high efficiency, economy and low pollution. Background Art

[0002] Chemical raw materials are often contaminated by heavy metal or transition metal ions, such as iron, copper, lead, cadmium, etc., during production, storage or use. These metal ions not only reduce the purity of chemical raw materials and affect product quality, but may also cause catalyst poisoning or other adverse reactions in downstream processes.

[0003] Currently common metal ion removal technologies include solvent extraction, chelation, sedimentation, electrochemistry, etc., but all of the above methods have disadvantages to varying degrees.

[0004] Chelation is a common way to remove heavy metal ions. Commonly used adsorbent materials for chelation include clay, stone powder, fly ash, etc. Its mechanism of action is mainly to form ionic bonds or covalent bonds with heavy metal ions. Chelation or hydrogen bonding makes the adsorbent material have cage molecules similar to a mesh structure, thereby achieving the purpose of adsorption and removal of heavy metal ions. However, this method is acceptable for water purification, but for many acidic, alkaline or reactive chemical reagents, the types of adsorbents available are very limited. At the same time, the adsorbent is mainly for Cd 2+ , Pb 2+ , Hg 2+ Cr 6+ , Cu 2+ etc. have strong adsorption effect, but the adsorption capacity is limited.

[0005] The electrochemical method is a method of eliminating metal ions by reducing them through electrolysis. However, this method consumes a lot of electricity and cannot reduce the ion concentration to trace amounts. Therefore, this method is generally only used to treat wastewater with high concentrations and low requirements for heavy metal content.

[0006] Solvent extraction uses the difference in solubility of metal ions in different solvents to enrich and separate metal ions. However, the solvent used for extraction is very expensive and the amount used is large.

[0007] Sedimentation is the process of converting dissolved heavy metal ions into insoluble heavy metal compounds, which are then removed from wastewater by precipitation or flotation. Commonly used methods include hydroxide precipitation, sulfide precipitation, ferrite co-precipitation, redox precipitation, etc. The problem with this method is that the precipitated particles are small and difficult to separate. Moreover, it is difficult to separate Na + , K + Ion removal. Summary of the invention

[0008] The invention provides a method for removing metal ions in a chemical reagent, so as to remove the metal ions to below 100 ppb.

[0009] The method for removing metal ions in a chemical reagent provided by the present invention comprises:

[0010] Dissolving a chemical reagent in a first solvent to prepare a mixed solution, adjusting the solution to be acidic, and performing ion exchange through a cation exchange resin;

[0011] The chemical reagent after the ion exchange removes the first solvent.

[0012] In a preferred embodiment, the chemical reagent may be a solid compound (under ≤50° C.), especially a neutral or acidic compound, especially an organic compound, such as one or more of alcohols, acids, phenols, ethers, esters, hydrocarbons, halogenated hydrocarbons, amides, thioethers, nitriles, ketones, sugars, etc.

[0013] In a preferred embodiment, the cation exchange resin is pretreated before use, and the pretreatment includes:

[0014] The cation exchange resin column is rinsed with an alkaline solution and then the residual base is rinsed with water;

[0015] The cation exchange resin column is flushed with acid and then the residual acid is flushed with water.

[0016] In a preferred embodiment, the base is preferably one or more of hydroxide and ammonia.

[0017] In a preferred embodiment, the alkaline solution is preferably an aqueous solution of an alkali, such as aqueous ammonia, potassium hydroxide solution, sodium hydroxide solution, and the like.

[0018] In a preferred embodiment, the concentration of the alkaline solution is preferably 0.001-0.1 mol / L, more preferably 0.005-0.05 mol / L, more preferably 0.01-0.02 mol / L.

[0019] In a preferred embodiment, the alkaline solution is at least analytically pure.

[0020] In a preferred embodiment, the amount of the alkaline solution is at least 1 times (volume) of the cation exchange resin column, preferably at least 2 times, and more preferably at least 3 times.

[0021] In a preferred embodiment, the alkaline solution flushes the cation exchange resin column through a circulation pump, and more preferably, the circulation time is preferably at least 5 times, preferably at least 8 times, and more preferably at least 10 times the volume of the cation exchange resin column.

[0022] In a preferred embodiment, the water used to wash away the residual alkali is at least 1 times, preferably at least 2 times, and more preferably at least 3 times the volume of the ion exchange resin column.

[0023] In a preferred embodiment, the acid refers to an aqueous solution, and is preferably one or more of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid.

[0024] In a preferred embodiment, the concentration of the acid is preferably 0.001-0.1 mol / L, more preferably 0.005-0.05 mol / L, more preferably 0.01-0.02 mol / L.

[0025] In a preferred embodiment, the acid is at least analytically pure.

[0026] In a preferred embodiment, the amount of the acid used is at least 1 times (volume) of the cation exchange resin column, preferably at least 2 times, and more preferably at least 3 times.

[0027] In a preferred embodiment, the acid is flushed through the cation exchange resin column by a circulation pump. More preferably, the circulation time is preferably at least 5 times, preferably at least 8 times, more preferably at least 10 times the volume of the cation exchange resin column.

[0028] In a preferred embodiment, the water used to wash the residual acid is at least 1 times, preferably at least 2 times, and more preferably at least 3 times the volume of the ion exchange resin column.

[0029] In a preferred embodiment, removing the first solvent by the chemical reagent after ion exchange may be removing the first solvent by evaporation, or, in another preferred embodiment, refers to:

[0030] The solution of the chemical reagent and the first solvent after ion exchange is mixed with a second solvent, where the second reagent is a solvent that can precipitate the chemical reagent from the first solvent (eg, the chemical reagent is slightly soluble, poorly soluble or insoluble in the second solvent), and the precipitated product is collected and dried.

[0031] In a preferred embodiment, the chemical reagent is dissolved in the first solvent to prepare a mixed solution, and the concentration of the chemical reagent is preferably 0.01-1 mol / L, more preferably 0.05-0.5 mol / L, and more preferably 0.1-0.2 mol / L.

[0032] In a preferred embodiment, the adjustment to acidity is performed with an inorganic acid, and more preferably, the inorganic acid can be one or more of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid.

[0033] In a preferred embodiment, the adjustment to acidity is to adjust the pH value to ≤5, more preferably 3-5, such as 3, 3.5, 4, 4.5.

[0034] In a preferred embodiment, during the ion exchange process, the volume of the mixed solution is at least 3 times, more preferably at least 5 times, more preferably 8-15 times, more preferably 10-12 times the volume of the cation exchange resin column.

[0035] In a preferred embodiment, during the ion exchange process, the flow rate of the mixed solution in the cation exchange resin column is 1-10 min / cation exchange resin column volume, more preferably 2-8 min / cation exchange resin column volume, more preferably 3-7 min / cation exchange resin column volume, more preferably 5-6 min / cation exchange resin column volume.

[0036] In a preferred embodiment, during the ion exchange process, the mixed solution is circulated in the cation exchange resin column by a circulation pump, and the number of cycles is preferably at least 2 times, more preferably 3-6 times, and more preferably 4-5 times.

[0037] More preferably, each cycle requires at least 20 min, more preferably 30-90 min, more preferably 40-75 min, more preferably 50-60 min.

[0038] In the context of the present invention, if not otherwise specified, the time for one column volume refers to the time for a liquid (such as an alkaline solution, an acid, water, a mixed solution, etc.) to pass through a cation exchange resin column. One cycle = one column volume time x the multiple of the amount of liquid (such as an alkaline solution, an acid, water, a mixed solution, etc.) compared to the cation exchange resin column. For example, if the volume of the mixed solution is 3 times the volume of the cation exchange resin column, then one cycle is 3 times the volume of the cation exchange resin column.

[0039] In a preferred embodiment, the first solvent can be one or more of water, alcohol, ether, ketone, ester, aliphatic hydrocarbon, aromatic hydrocarbon, halogenated hydrocarbon, heterocyclic compound, amide, dimethyl sulfoxide, nitrile, furan, pyridine, for example, it can be one or more of ethanol, methanol, ether, acetone, ethyl acetate, methyl acetate, butyl acetate, pentane, hexane, benzene, toluene, xylene, dichloromethane, chloroform, tetrachloromethane, dichloroethane, chlorobenzene, dioxane, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, tetrahydrofuran.

[0040] In a preferred embodiment, the second solvent is different from the first solvent and can be one or more selected from water, alcohol, ether, ketone, ester, aliphatic hydrocarbon, aromatic hydrocarbon, halogenated hydrocarbon, heterocyclic compound, amide, dimethyl sulfoxide, nitrile, furan, pyridine, for example, it can be one or more of ethanol, methanol, ether, acetone, ethyl acetate, methyl acetate, butyl acetate, pentane, hexane, benzene, toluene, xylene, dichloromethane, chloroform, tetrachloromethane, dichloroethane, chlorobenzene, dioxane, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, tetrahydrofuran.

[0041] In a preferred embodiment, the volume of the second solvent is at least 1 times, more preferably at least 2 times, such as 3-8 times, more preferably 4-7 times, more preferably 5-6 times, the volume of the first solvent.

[0042] In the above content of the present invention, the cation exchange resin comprises: 1) a mesh skeleton whose matrix is ​​a polymer, and 2) an active group sulfonic acid group linked to the skeleton.

[0043] Preferably, the cation exchange resin is a polystyrene cation exchange resin, the matrix of which is a network skeleton formed by copolymerization of styrene monomer and diphenylethylene crosslinking agent.

[0044] In a preferred embodiment, the cation exchange resin is solid spherical particles with a particle size of 0.3-1.2 mm.

[0045] Compared with other methods for removing metal impurities, the present invention has the following advantages: ion exchange resin will not contaminate compounds; and the removal effect of ion exchange resin is better, and metal ions can be removed to below 100 ppb, and the overall metal ion removal rate exceeds 90%; the present invention can be applied to large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is the effect diagram of removing metal ions in Example 1;

[0047] Figure 2 This is a flow chart of the removal of metal ions according to the present invention. DETAILED DESCRIPTION

[0048] The present invention provides a method for removing metal ions from chemical reagents. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0049] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. In the specification and claims of the present invention, the term "at least" means greater than or equal to.

[0050] Embodiment 1:

[0051] Commercially available polystyrene type cation exchange resins are solid spherical particles with a particle size of 0.3-1.2 mm. The spatial structure is a network structure polymer compound with functional groups, which includes: 1) a network skeleton formed by copolymerization of styrene monomer and diphenylethylene crosslinker, and 2) an active group sulfonic acid group linked to the skeleton.

[0052] Step 1, resin pretreatment

[0053] The newly purchased cation exchange resin has not been activated and can only be used after being activated with acid or alkali. In this embodiment, the acid or alkali is phosphoric acid (analytical grade) and ammonia water (analytical grade).

[0054] First, use 0.01 mol / l ammonia water to flush the cation exchange resin column back and forth through a circulation pump. The amount of dilute ammonia water used is three times the amount of the cation exchange resin column. The specific circulation time is calculated based on the column volume, and circulating ten times the volume of the cation exchange resin column is optimal.

[0055] After the alkali pretreatment, the alkali remaining in the cation exchange resin column is washed with purified water three times the volume of the cation exchange resin column.

[0056] Next, 0.01 mol / l phosphoric acid is used to flush the cation exchange resin column back and forth through a circulation pump. The amount of phosphoric acid used is three times that of the cation exchange resin column. The specific circulation time is calculated based on the column volume, and circulating ten times the volume of the cation exchange resin column is optimal.

[0057] After acid pretreatment, the residual acid in the cation exchange resin column was washed with purified water three times the volume of the cation exchange resin column.

[0058] Step 2, ion exchange

[0059] The raw material compound is commercially available methyl paraben, and metal ion detection shows that it is mixed with Na, K, Mg, Ca, and Fe ions, such as Figure 1 As shown, the sodium content is 1250 ppb, the potassium content is 554 ppb, the calcium content is about 208 ppb, the iron content is about 612 bbp, and the magnesium content is about 52 ppb.

[0060] Reference Figure 2 Methyl p-hydroxybenzoate was dissolved in ethanol to obtain a mixed solution (0.1 mol / l). Phosphoric acid was used to adjust the mixed solution to pH 4, and then the mixed solution was circulated through a cation exchange resin column. The ratio of resin volume to solution volume was 1:10. The circulation rate of the solution in the cation exchange resin column was 5 min for one cation exchange resin column volume, and one solution circulation was completed in 50 min. The circulation was repeated five times.

[0061] Step 3, precipitate and dry the compound

[0062] After the ion exchange, the mixed solution was added into water (volume ratio, ethanol: water = 1:5), methyl p-hydroxybenzoate was precipitated in the water, and the purified compound was obtained by suction filtration and drying.

[0063] ICP-MS detects metal ion content, refer to Figure 1 The metal ion content in the methyl paraben treated by the present invention is less than 100 ppb, especially the sodium, magnesium and calcium ions are all below 10 ppb, and the removal effect is also good for ions such as K and Na that are difficult to remove by ordinary methods. In this embodiment, the overall metal ion concentration is reduced by 90.08%.

[0064] Embodiment 2:

[0065] Step 1, resin pretreatment

[0066] Newly purchased cation exchange resin (see Example 1) was activated.

[0067] First, use 0.01 mol / l ammonia water to flush the cation exchange resin column back and forth through a circulation pump. The amount of dilute ammonia water used is three times the volume of the cation exchange resin column, and the circulation is ten times the volume of the cation exchange resin column.

[0068] After the alkali pretreatment, the alkali remaining in the cation exchange resin column is washed with purified water three times the volume of the cation exchange resin column.

[0069] Next, 0.01 mol / l phosphoric acid is used to flush the cation exchange resin column back and forth through a circulation pump. The amount of phosphoric acid used is three times the volume of the cation exchange resin column, and the circulation is ten times the volume of the cation exchange resin column.

[0070] After acid pretreatment, the residual acid in the cation exchange resin column was washed with purified water three times the volume of the cation exchange resin column.

[0071] Step 2, ion exchange

[0072] Reference Figure 2 The raw material compound is commercially available p-aminophenol. Metal ion detection shows that it is mixed with Na, K, Mg, Ca, and Fe ions, such as Figure 1 As shown, the Na content is 556 ppb, the magnesium content is about 190 ppb, the potassium content is 3382 ppb, the calcium content is about 540 ppb, and the iron content is about 997 bbp.

[0073] Para-aminophenol was dissolved in ethanol to obtain a mixed solution (0.1 mol / l), phosphoric acid was used to adjust the mixed solution to a pH value of 4, and then circulated through a cation exchange resin column, the resin volume to solution volume ratio was 1:10, the circulation speed of the solution in the cation exchange resin column was 5 minutes for one cation exchange resin column volume, 50 minutes to complete one solution circulation, and the circulation was repeated five times.

[0074] Step 3, precipitate and dry the compound

[0075] After the ion exchange, the mixed solution was added into water (volume ratio, ethanol: water = 1:5), the compound was precipitated in the water, and the purified compound was obtained by suction filtration and drying.

[0076] ICP-MS was used to detect the metal ion content, see Table 1.

[0077] Comparative Example 1:

[0078] The newly purchased cation exchange resin (see Example 1) was not activated.

[0079] Reference Figure 2 , the raw material compound is commercially available p-aminophenol (see Example 1).

[0080] Para-aminophenol was dissolved in ethanol to obtain a mixed solution (0.1 mol / l), phosphoric acid was used to adjust the mixed solution to a pH value of 4, and then circulated through a cation exchange resin column, the resin volume to solution volume ratio was 1:10, the circulation speed of the solution in the cation exchange resin column was 5 minutes for one cation exchange resin column volume, 50 minutes to complete one solution circulation, and the circulation was repeated five times.

[0081] After the ion exchange, the mixed solution was added into water (volume ratio, ethanol: water = 1:5), the compound was precipitated in the water, and the purified compound was obtained by suction filtration and drying.

[0082] ICP-MS was used to detect the metal ion content, see Table 1.

[0083] Comparative Example 2:

[0084] Step 1, resin pretreatment

[0085] Referring to Example 2, a newly purchased cation exchange resin was activated.

[0086] First, use 0.01 mol / l ammonia water to flush the cation exchange resin column back and forth through a circulation pump. The amount of dilute ammonia water used is three times the volume of the cation exchange resin column, and the circulation is ten times the volume of the cation exchange resin column.

[0087] After the alkali pretreatment, the alkali remaining in the cation exchange resin column is washed with purified water three times the volume of the cation exchange resin column.

[0088] Next, 0.01 mol / l phosphoric acid is used to flush the cation exchange resin column back and forth through a circulation pump. The amount of phosphoric acid used is three times the volume of the cation exchange resin column, and the circulation is ten times the volume of the cation exchange resin column.

[0089] After acid pretreatment, the residual acid in the cation exchange resin column was washed with purified water three times the volume of the cation exchange resin column.

[0090] Step 2, ion exchange

[0091] Referring to Example 2, the raw material compound is commercially available p-aminophenol.

[0092] p-Aminophenol was dissolved in ethanol to obtain a mixed solution (0.1 mol / l), the pH value was adjusted to 6 with phosphoric acid, and then circulated through a cation exchange resin column, the resin volume to solution volume ratio was 1:10, the circulation speed of the solution in the cation exchange resin column was 5 minutes for one cation exchange resin column volume, and one solution circulation was completed in 50 minutes, and the cycle was repeated five times.

[0093] Step 3, precipitate and dry the compound

[0094] After the ion exchange, the mixed solution was added into water (volume ratio, ethanol: water = 1:5), and the compound p-aminophenol was precipitated in the water, which was filtered and dried to obtain the purified compound.

[0095] ICP-MS was used to detect the metal ion content, see Table 1.

[0096] Comparative Example 3:

[0097] Step 1, resin pretreatment

[0098] Referring to Example 2, a newly purchased cation exchange resin was activated.

[0099] First, use 0.01 mol / l ammonia water to flush the cation exchange resin column back and forth through a circulation pump. The amount of dilute ammonia water used is three times the volume of the cation exchange resin column, and the circulation is ten times the volume of the cation exchange resin column.

[0100] After the alkali pretreatment, the alkali remaining in the cation exchange resin column is washed with purified water three times the volume of the cation exchange resin column.

[0101] Next, 0.01 mol / l phosphoric acid is used to flush the cation exchange resin column back and forth through a circulation pump. The amount of phosphoric acid used is three times the volume of the cation exchange resin column, and the circulation is ten times the volume of the cation exchange resin column.

[0102] After acid pretreatment, the residual acid in the cation exchange resin column was washed with purified water three times the volume of the cation exchange resin column.

[0103] Step 2, ion exchange

[0104] Referring to Example 2, the raw material compound is commercially available p-aminophenol.

[0105] p-Aminophenol was dissolved in ethanol to obtain a mixed solution (0.1 mol / l), the pH value was adjusted to 5 with phosphoric acid, and then circulated through a cation exchange resin column, the resin volume to solution volume ratio was 1:10, the circulation speed of the solution in the cation exchange resin column was 5 minutes for one cation exchange resin column volume, and one solution circulation was completed in 50 minutes, and the cycle was repeated five times.

[0106] Step 3, precipitate and dry the compound

[0107] After the ion exchange, the mixed solution was added into water (volume ratio, ethanol: water = 1:5), and the compound p-aminophenol was precipitated in the water, which was filtered and dried to obtain the purified compound.

[0108] ICP-MS was used to detect the metal ion content, see Table 1.

[0109] Comparative Example 4:

[0110] Step 1, resin pretreatment

[0111] Referring to Example 2, a newly purchased cation exchange resin was activated.

[0112] First, use 0.01 mol / l ammonia water to flush the cation exchange resin column back and forth through a circulation pump. The amount of dilute ammonia water used is three times the volume of the cation exchange resin column, and the circulation is ten times the volume of the cation exchange resin column.

[0113] After the alkali pretreatment, the alkali remaining in the cation exchange resin column is washed with purified water three times the volume of the cation exchange resin column.

[0114] Next, 0.01 mol / l phosphoric acid is used to flush the cation exchange resin column back and forth through a circulation pump. The amount of phosphoric acid used is three times the volume of the cation exchange resin column, and the circulation is ten times the volume of the cation exchange resin column.

[0115] After acid pretreatment, the residual acid in the cation exchange resin column was washed with purified water three times the volume of the cation exchange resin column.

[0116] Step 2, ion exchange

[0117] Referring to Example 2, the raw material compound is commercially available p-aminophenol.

[0118] p-Aminophenol was dissolved in ethanol to obtain a mixed solution (0.1 mol / l), the pH value was adjusted to 3 with phosphoric acid, and then circulated through a cation exchange resin column, the resin volume to solution volume ratio was 1:10, the circulation speed of the solution in the cation exchange resin column was 5 min for one cation exchange resin column volume, and one solution circulation was completed in 50 min, and the cycle was repeated five times.

[0119] Step 3, precipitate and dry the compound

[0120] After the ion exchange, the mixed solution was added into water (volume ratio, ethanol: water = 1:5), and the compound p-aminophenol was precipitated in the water, which was filtered and dried to obtain the purified compound.

[0121] ICP-MS was used to detect the metal ion content, see Table 1.

[0122] Table 2, metal ion removal effect of examples

[0123] Metal ions Sodium Na / ppb Magnesium Mg / ppb Potassium K / ppb Calcium Ca / ppb Iron Fe / ppb Unprocessed raw materials 556 190 3382 540 997 Example 2 111 4 28 12 61 Comparative Example 1 490 289 1911 627 276 Comparative Example 2 197 203 3514 335 264 Comparative Example 3 258 98 624 148 98 Comparative Example 4 199 34 190 21 196

[0124] In the purified compounds of Example 2, except for Na, the concentrations of other metal ions are basically below 100 ppb, the concentration of Na ions is also close to 100 ppb, the removal rate of K ions is as high as more than 99%, the removal rates of Mg and Ca ions are about 98%, and the removal rate of Fe ions is about 94%. However, the effect of unactivated resin on the removal of metal ions is very limited. In addition, the pH value is very important for the removal of metal ions. As shown in Comparative Examples 2-3, when the pH value is ≥5, the metal ion removal effect is worse than that of pH = 4. In addition, when the pH value is ≤3, the metal ion removal effect is also worse than that of pH = 4, but the overall removal effect is better than that of Comparative Examples 2-3.

[0125] Embodiment 3:

[0126] Step 1, resin pretreatment

[0127] Referring to Example 2, a newly purchased cation exchange resin was activated.

[0128] First, use 0.01 mol / l ammonia water to flush the cation exchange resin column back and forth through a circulation pump. The amount of dilute ammonia water used is three times the volume of the cation exchange resin column, and the circulation is ten times the volume of the cation exchange resin column.

[0129] After the alkali pretreatment, the alkali remaining in the cation exchange resin column is washed with purified water three times the volume of the cation exchange resin column.

[0130] Next, 0.01 mol / l phosphoric acid is used to flush the cation exchange resin column back and forth through a circulation pump. The amount of phosphoric acid used is three times the volume of the cation exchange resin column, and the circulation is ten times the volume of the cation exchange resin column.

[0131] After acid pretreatment, the residual acid in the cation exchange resin column was washed with purified water three times the volume of the cation exchange resin column.

[0132] Step 2, ion exchange

[0133] Referring to Example 2, the raw material compound is commercially available p-aminophenol.

[0134] p-Aminophenol was dissolved in ethyl acetate to obtain a mixed solution (0.1 mol / l), phosphoric acid was used to adjust the mixed solution to a pH value of 4, and then the mixed solution was circulated through a cation exchange resin column, the resin volume to solution volume ratio was 1:10, the circulation speed of the solution in the cation exchange resin column was 5 min for one cation exchange resin column volume, 50 min to complete one solution circulation, and the circulation was repeated five times.

[0135] Step 3, precipitate and dry the compound

[0136] After the ion exchange, the mixed solution was added into petroleum ether (volume ratio, ethyl acetate: petroleum ether=1:5), p-aminophenol was precipitated in water, and the purified compound was obtained by suction filtration and drying.

[0137] ICP-MS was used to detect the metal ion content, see Table 2.

[0138] Table 2, metal ion removal effect of examples

[0139] Metal ions Sodium Na / ppb Magnesium Mg / ppb Potassium K / ppb Calcium Ca / ppb Iron Fe / ppb Before purification 556 190 3382 540 997 After purification 101 21 59 99 38

[0140] The metal ion concentration in the purified compound of this example is substantially below 100 ppb.

[0141] The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equalization changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims

1. A method for removing metal ions from a chemical reagent, characterized in that: include: Dissolving a chemical reagent in a first solvent to prepare a mixed solution, adjusting the solution to be acidic, and performing ion exchange through a cation exchange resin; The chemical reagent after ion exchange removes the first solvent; Preferably, the cation exchange resin comprises: a network skeleton whose matrix is ​​a polymer and sulfonic acid groups which are active groups linked to the skeleton.

2. The method according to claim 1, characterized in that The cation exchange resin is pretreated before use, and the pretreatment includes: The cation exchange resin column is rinsed with an alkaline solution and then the residual base is rinsed with water; The cation exchange resin column is flushed with acid and then the residual acid is flushed with water.

3. The method according to claim 2, characterized in that The alkaline solution is selected from ammonia water, potassium hydroxide solution, and sodium hydroxide solution; preferably, the concentration of the alkaline solution is 0.001-0.1 mol / L, more preferably 0.005-0.05 mol / L, more preferably 0.01-0.02 mol / L; preferably, the amount of the alkaline solution is at least 1 times, preferably at least 2 times, and more preferably at least 3 times that of the cation exchange resin column; More preferably, the alkaline solution is flushed through the cation exchange resin column by a circulation pump. More preferably, the circulation time is preferably at least 5 times, preferably at least 8 times, more preferably at least 10 times the volume of the cation exchange resin column.

4. The method according to claim 2, characterized in that: The acid is one or more of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid; preferably, the concentration of the acid is preferably 0.001-0.1 mol / L, more preferably 0.005-0.05 mol / L, more preferably 0.01-0.02 mol / L; preferably, the amount of the acid is at least 1 times, preferably at least 2 times, more preferably at least 3 times of the amount of the cation exchange resin column; More preferably, the acid is flushed through the cation exchange resin column by a circulation pump, and more preferably, the circulation time is preferably at least 5 times, preferably at least 8 times, more preferably at least 10 times the volume of the cation exchange resin column.

5. The method according to claim 2, characterized in that: The residual acid is washed with water, and the amount of water used is at least 1 times, preferably at least 2 times, and more preferably at least 3 times the volume of the ion exchange resin column; and / or The water used to wash away the residual alkali is at least 1 times, preferably at least 2 times, and more preferably at least 3 times the volume of the ion exchange resin column.

6. The method according to claim 1, characterized in that The adjustment to acidity is to adjust the pH value to ≤5, more preferably 3-5, such as 3, 3.5, 4, 4.5; preferably, the pH value is adjusted with an inorganic acid, and more preferably, the inorganic acid can be one or more of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid.

7. The method according to claim 1, characterized in that The chemical reagent is dissolved in the first solvent to prepare a mixed solution, and the concentration of the chemical reagent is preferably 0.01-1 mol / L, more preferably 0.05-0.5 mol / L, and more preferably 0.1-0.2 mol / L.

8. The method according to claim 1, characterized in that Removing the first solvent by the chemical reagent after ion exchange may be removing the first solvent by evaporation, or may refer to: The solution of the chemical reagent and the first solvent after ion exchange is mixed with a second solvent, wherein the second reagent is a solvent capable of precipitating the chemical reagent from the first solvent, and the precipitated product is collected and dried; Preferably, the first solvent and the second solvent are different; more preferably, the first solvent and the second solvent are independently selected from one or more of water, alcohol, ether, ketone, ester, aliphatic hydrocarbon, aromatic hydrocarbon, halogenated hydrocarbon, heterocyclic compound, amide, dimethyl sulfoxide, nitrile, furan, pyridine, for example, it can be one or more of ethanol, methanol, ether, acetone, ethyl acetate, methyl acetate, butyl acetate, pentane, hexane, benzene, toluene, xylene, dichloromethane, chloroform, tetrachloromethane, dichloroethane, chlorobenzene, dioxane, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, tetrahydrofuran; More preferably, the volume of the second solvent is at least 1 times, more preferably at least 2 times, such as 3-8 times, more preferably 4-7 times, more preferably 5-6 times, the volume of the first solvent.

9. The method according to claim 1, characterized in that: During the ion exchange process, the volume of the mixed solution is at least 3 times, more preferably at least 5 times, more preferably 8-15 times, more preferably 10-12 times the volume of the cation exchange resin column.

10. The method according to claim 1, characterized in that In the ion exchange process, the mixed solution has a flow rate of 1-10 min / cation exchange resin column volume in the cation exchange resin column, more preferably 2-8 min / cation exchange resin column volume, more preferably 3-7 min / cation exchange resin column volume, more preferably 5-6 min / cation exchange resin column volume; More preferably, in the ion exchange process, the mixed solution circulates in the cation exchange resin column by a recycle pump, and the number of cycles is preferably at least 2 times, more preferably 3-6 times, more preferably 4-5 times; More preferably, the time required for each circulation is at least 20 min, more preferably 30-90 min, more preferably 40-75 min, more preferably 50-60 min.

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