Use of phosphorus adsorbing resin for selective adsorption of phosphorus from phosphorus-containing wastewater and method

Abstract

This invention relates to the use and method of a phosphorus adsorption resin for selectively adsorbing phosphorus from phosphorus-containing wastewater. The phosphorus adsorption resin comprises a weak acid cation exchange resin and Fe supported on its surface. 3+ The phosphorus-containing wastewater has a pH of 0.8-3.0, a phosphorus concentration of 0.1-5 g / L, and also contains 0.1-1 g / L of Ca. The phosphorus adsorption resin is prepared by the following steps: i) reacting a weak acid cation exchange resin with an iron salt solution, wherein the iron salt is selected from one or more of ferric sulfate, ferric chloride, ferric nitrate, ferric citrate, and ferric tartrate; ii) after the reaction, solid-liquid separation is performed to obtain Fe-loaded... 3+ The method of this invention achieves highly selective adsorption of phosphorus (≥95%), good separation of phosphorus and calcium, and an iron-to-calcium ratio ≥800 in the phosphorus-enriched back-extraction solution, which can be used to prepare battery-grade iron phosphate.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment. Specifically, this invention relates to the use and method of a phosphorus adsorption resin for selectively adsorbing phosphorus from phosphorus-containing wastewater. Background Technology

[0002] With the discharge of industrial wastewater, agricultural runoff, and domestic sewage, excessive phosphorus content in water bodies has become one of the main causes of eutrophication. Traditional phosphorus removal methods (such as chemical precipitation and biological treatment) suffer from high costs, low efficiency, and the potential for secondary pollution. For example, chemical precipitation requires the addition of large amounts of aluminum or iron salts, which not only increases sludge volume but may also leave residual metal ions; biological treatment requires strict operating conditions, and its phosphorus removal effect is unstable.

[0003] In recent years, adsorption methods have received widespread attention due to their advantages such as simple operation, controllable cost, and environmental friendliness. Although existing adsorbents have a certain phosphorus removal effect, they suffer from poor selectivity between phosphorus and impurity elements (especially calcium).

[0004] Therefore, developing a highly selective adsorption method to solve the problem of poor selectivity between phosphorus and impurity elements (especially calcium) in existing technologies has significant environmental and economic value. Summary of the Invention

[0005] One object of the present invention is to provide an adsorption method capable of selectively adsorbing phosphorus.

[0006] Therefore, according to a first aspect, the present invention provides the use of a phosphorus adsorption resin for selectively adsorbing phosphorus from phosphorus-containing wastewater, characterized in that: the phosphorus adsorption resin comprises a weak acid cation exchange resin and Fe supported on its surface. 3+ The phosphorus-containing wastewater has a pH of 0.8-3.0, a phosphorus concentration of 0.1-5 g / L, and also contains 0.1-1 g / L of Ca; the preparation method of the phosphorus adsorption resin includes the following steps: i) A weak acid cation exchange resin is reacted with an iron salt solution, wherein the iron salt is selected from one or more of ferric sulfate, ferric chloride, ferric nitrate, ferric citrate, and ferric tartrate; ii) After the reaction is complete, solid-liquid separation is performed to obtain supported Fe. 3+ Phosphorus adsorption resin.

[0007] According to a second aspect, the present invention provides a method for selectively adsorbing phosphorus from phosphorus-containing wastewater, comprising the following steps: (a) The above-mentioned phosphorus adsorption resin is contacted with phosphorus-containing wastewater for extraction. After extraction, the phosphorus-loaded phosphorus adsorption resin is recovered by solid-liquid separation. (b) The phosphorus-loaded phosphorus adsorption resin is washed and back-extracted sequentially using a detergent and a back-extracting agent to obtain a phosphorus-enriched back-extracting solution and a back-extracted phosphorus adsorption resin.

[0008] The method of this invention can achieve highly selective adsorption of phosphorus (≥95%), good separation of phosphorus and calcium, and the iron-to-calcium ratio in the phosphorus-enriched back-extraction solution is ≥800, which can be used to prepare battery-grade iron phosphate. Detailed Implementation

[0009] The various aspects of the invention, as well as further objects, features and advantages, will be set forth more fully below.

[0010] Applications of phosphorus adsorption resins According to a first aspect, the present invention provides the use of a phosphorus adsorption resin for selectively adsorbing phosphorus from phosphorus-containing wastewater, characterized in that: the phosphorus adsorption resin comprises a weak acid cation exchange resin and Fe supported on its surface. 3+ The phosphorus-containing wastewater has a pH of 0.8-3.0, a phosphorus concentration of 0.1-5 g / L, and also contains 0.1-1 g / L of Ca; the preparation method of the phosphorus adsorption resin includes the following steps: i) A weak acid cation exchange resin is reacted with an iron salt solution, wherein the iron salt is selected from one or more of ferric sulfate, ferric chloride, ferric nitrate, ferric citrate, and ferric tartrate; ii) After the reaction is complete, solid-liquid separation is performed to obtain supported Fe. 3+ Phosphorus adsorption resin.

[0011] Preferably, the weak acid cation exchange resin comprises resins of formula (I) and / or formula (II): (I) (II) in: M is the base resin, R1 is either -CH(COR5)2 or -(CH2) q COR6, R2 represents hydrogen, -CH(COR5)2, or -(CH2). q COR6, -CH2P(O)(OH)(Ph), -CH2P(O)(OH)2, -(CH2) y P(O)(R7)2 or -(CH2) t SO3H, A is -N- or -N((CH2) n NH-)2, where n is an integer from 2 to 9, R3 can be -CH2P(O)(OH)(Ph), -CH2P(O)(OH)2, or -(CH2). yP(O)(R7)2, R4 represents hydrogen, -CH2P(O)(OH)(Ph), or -(CH2). y P(O)(R7)2 or -(CH2) t SO3H, R5 is selected from hydroxyl groups, optionally halogenated C. 1- C 10 alkoxy groups, optionally C1-C 10 Alkyl or halogen-substituted amino groups, R6 is selected from hydroxyl groups, or optionally halogenated C. 1- C 10 alkoxy groups, optionally C1-C 10 Alkyl or halogen-substituted amino groups, R7 is selected from phenyl or optionally halogenated C. 1- C 10 alkoxy groups, y, t, and q are any integers from 1 to 9. Ph represents phenyl, and halogens are Cl or Br.

[0012] The present invention does not specifically limit M, but preferably it is selected from polystyrene resin, copolymer of styrene and divinylbenzene, phenolic resin, polyacrylic resin and silicone resin. More preferably, M is selected from polystyrene resin and copolymer of styrene and divinylbenzene.

[0013] Preferably, R5 is selected from hydroxyl groups, optionally halogenated C5. 1- C8 alkoxy groups, or amino groups optionally substituted with C1-C8 alkyl groups or halogens.

[0014] Preferably, R6 is selected from hydroxyl groups, optionally halogenated C6. 1- C8 alkoxy groups, or amino groups optionally substituted with C1-C8 alkyl groups or halogens.

[0015] y, t, and q can be, for example, 1, 2, 3, 4, 5, 6, 7, 8, or 9. Preferably, y, t, and q are 1 or 2, respectively.

[0016] Preferably, R1 is selected from the following groups: , , , , , or ,in This is the site where the group connects to N.

[0017] Preferably, R2 is selected from hydrogen and the following groups: , , , , , , , , , , , , , , , , , or , in This is the site where the group connects to N.

[0018] Preferably, R3 is selected from the following groups: , , , , , , , , or , in This is the site where the group connects to A.

[0019] Preferably, R4 is selected from hydrogen and the following groups: , , , , , , , , , or ,in This is the site where the group connects to A.

[0020] Preferably, the weak acid cation exchange resin has a structure selected from the following: , , , , , , , , , , , , , , , , , , or , M is selected from polystyrene resin and copolymers of styrene and divinylbenzene.

[0021] More preferably, the weak acid cation exchange resin has a structure selected from the following: , , , , or , M is selected from polystyrene resin and copolymers of styrene and divinylbenzene.

[0022] Preferably, the weak acid cation exchange resin is a macroporous resin.

[0023] As used herein, the pore size of the macroporous resin is in the range of 10-1000 nm, preferably 20-100 nm.

[0024] The weak acid cation exchange resin can be prepared by a method including the following steps: S11. A compound of formula III, IV, or V, with a molar ratio of primary amine resin to primary amine group of 1:0.75-1.75, preferably 1:0.8-1.5, is reacted in an alkaline solution with a concentration of 0.1-5 mol / L at a temperature of 40-120°C for 4-48 h to obtain an intermediate resin. The solute in the alkaline solution is one or a combination of two or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, ammonia, triethylamine, and calcium hydroxide. The solvent in the alkaline solution is one or a combination of two or more of water, ethanol, methanol, and N,N-dimethylformamide. The molar ratio of the solute in the alkaline solution to the primary amine group in the resin is 0.8-2.5:1, and the amount of solvent is 1-30 times the mass of the resin. S12. In the presence of formaldehyde, the intermediate resin is reacted with a phosphorus-containing substance of formula Va, Vb, or Vc at a temperature of 40-120°C for 4-48 h in an acidic solution or aqueous solution with a concentration of 0.1-6 mol / L to obtain the resin of formula (I). The solvent in the acidic solution is one or a mixture of water, ethanol, methanol, and N,N-dimethylformamide. The ratio of the amount of acid in the acidic solution to the molar amount of the primary amine group in the resin is 0.5-3:1. The molar ratio of the primary amine group of the resin matrix, formaldehyde, and phosphorus-containing substance of formula Va, Vb, or Vc is 1:1-1.5:0.5-1.75, preferably 1:1-1.25:0.8-1.5. (III), (IV), (v), (Va), (Vb), (Vc), S21. First, combine H2N-(CH2) n -NH-(CH2) n -NH2 and compounds of formula V in a molar ratio of 1.1-1.5:1, or A substitution reaction is carried out to obtain an intermediate of formula Vd. Then, a chloroform resin is reacted with the intermediate of formula Vd at a molar ratio of 1:(1.2-3) to obtain the resin of formula (II)), wherein the compound of V is as defined for step S11, and the reaction conditions of the chloroform resin with the intermediate of formula Vd are as described for step S11. (Vd) or, S31. In acidic or aqueous solutions, in the presence of formaldehyde, H2N-(CH2) q -C(O)R6 or H2N-(CH2) t -SO3H reacts with phosphorus-containing substances of formula Va, Vb, or Vc at a temperature of 40-120°C to obtain an intermediate compound, wherein the phosphorus-containing substances of formula Va or Vb and the reaction conditions are as described for step S12; then, the chlorinated resin reacts with the intermediate compound at a molar ratio of 1:(1.2-3) to obtain the resin of formula (I) or formula (II), wherein the amount of acid in the acidic solution is related to H2N-(CH2). q -C(O)R6 or H2N-(CH2) t The molar ratio of -SO3H is 0.5-3:1, and the H2N-(CH2) content is... q -C(O)R6 or H2N-(CH2) t The molar ratio of SO3H, formaldehyde, and phosphorus-containing substances of formula Va or Vb is 1:1-1.5:0.5-1.75, preferably 1:1-1.25:0.8-1.5. The reaction conditions of the chlorinated resin and the intermediate compound are as described for step S21. or, S41, makes H2N-(CH2) t-SO3H reacts with the compound of formula IV in an alkaline solution with a concentration of 0.1-5 mol / L at a temperature of 40-120°C for 4-48 h, with the compound of formula IV and reaction conditions as described for step S11, to obtain an intermediate compound; then, the chlorinated resin is reacted with the intermediate compound at a molar ratio of 1:(1.2-3) to obtain the resin of formula (I), with the reaction conditions of the chlorinated resin and the intermediate compound as described for step S21. R3 is as defined for Equation II. R5 is as defined for equation I. R6 is as defined for equation I. R7 is as defined for Equation II. y, t, q, n as defined with respect to Equation I or Equation II X = Cl, Br, or I.

[0025] Before steps S11, S12, S21, S31, and S41, the resin matrix can be pretreated, specifically referring to the resin pretreatment in patent application number 2023116291434.

[0026] The "chloro-2-methyl resin" mentioned in this application refers to a resin containing a chloromethyl (-CH2Cl) functional group.

[0027] Preferably, before step i), the weak acid cation exchange resin is washed with a 0.25-8 mol / L, preferably 0.25-1.25 mol / L sodium hydroxide or potassium hydroxide solution until the supernatant is alkaline. Then, the resin is washed with deionized water until it is neutral and filtered for later use.

[0028] Preferably, the iron salt solution is a ferric sulfate solution.

[0029] Preferably, after solid-liquid separation, the phosphorus adsorption resin is washed with water to remove the entrained iron salt solution.

[0030] Preferably, the iron salt solution contains Fe 3+ The concentration is 0.01-1.20 mol / L, more preferably 0.10-0.50 mol / L.

[0031] The reaction between the weak acid cation exchange resin and the iron salt solution can be carried out using a fixed-bed resin column or a fluidized-bed resin column.

[0032] Preferably, the reaction flow rate is 1-30 BV / h, more preferably 1-5 BV / h.

[0033] Preferably, the reaction time is 1-30 h, more preferably 2-6 h.

[0034] Preferably, the reaction volume of the iron salt solution is 2-8 BV, more preferably 3-5 BV.

[0035] Preferably, the initial pH of the iron salt solution is 0.5-2.3, more preferably 0.8-2.0.

[0036] Preferably, the water used for washing can be deionized water, system recycled water, or MVR condensate recycled water.

[0037] Preferably, the pH of the phosphorus-containing wastewater is 1-2.5, more preferably 1.5-2.

[0038] Preferably, the phosphorus concentration of the phosphorus-containing wastewater is 0.1-4 g / L.

[0039] Furthermore, the phosphorus-containing wastewater also contains Al 0.1-5 g / L.

[0040] Preferably, phosphorus is present as one or a mixture of phosphate, monohydrogen phosphate and dihydrogen phosphate.

[0041] The phosphorus-containing wastewater can be one or more of the following: phosphogypsum leachate, washing water from washing iron phosphate products, phosphorus-containing liquid from lithium iron phosphate pre-extraction, and industrial phosphorus-containing wastewater.

[0042] According to a second aspect, the present invention provides a method for selectively adsorbing phosphorus from phosphorus-containing wastewater, comprising the following steps: (a) The above-mentioned phosphorus adsorption resin is contacted with phosphorus-containing wastewater for extraction. After extraction, the phosphorus-loaded phosphorus adsorption resin is recovered by solid-liquid separation. (b) The phosphorus-loaded phosphorus adsorption resin is washed and back-extracted sequentially using a detergent and a back-extracting agent to obtain a phosphorus-enriched back-extracting solution and a back-extracted phosphorus adsorption resin.

[0043] Preferably, the extraction flow rate is 0.1-10 BV / h, more preferably, the extraction flow rate is 0.1-5 BV / h.

[0044] The extraction equipment can be, for example, a continuous ion exchange resin column or a valve array resin column.

[0045] The resin column can be, for example, a fluidized bed or a fixed bed.

[0046] When the resin is a fluidized bed, preferably, the fluid flow direction is perpendicular to the ground and flows from bottom to top.

[0047] Preferably, the extraction temperature is 10-80℃, more preferably, the extraction temperature is 20-50℃.

[0048] Preferably, the detergent is deionized water and / or an acid solution, more preferably an acid solution.

[0049] Preferably, the acid solution is one or a combination of at least two of hydrochloric acid, sulfuric acid, and nitric acid solutions; more preferably, the acid solution is a sulfuric acid solution.

[0050] Preferably, the pH of the acid solution is 0.5-6.0, more preferably 0.8-2.0.

[0051] Preferably, the flow rate during the washing process is 0.5-5 BV / h.

[0052] Preferably, the washing volume is 1-10 BV.

[0053] Preferably, the stripping agent is 0.5-4 mol / L sulfuric acid.

[0054] Preferably, the back-extraction flow rate is 0.5-5 BV / h.

[0055] Preferably, the number of back-extraction stages is 1-10, and the resin columns are connected in series and / or in parallel.

[0056] Preferably, the volume of single-column back-extraction is 0.2-10 BV, more preferably 1-5 BV.

[0057] The method of this invention can achieve highly selective adsorption of phosphorus (≥95%), good separation of phosphorus and calcium, and the iron-to-calcium ratio in the phosphorus-enriched back-extraction solution is ≥800, which can be used to prepare battery-grade iron phosphate.

[0058] The "selectivity" described in this invention is represented by the separation coefficient β of the metallic element, which is further derived from the following formula: β A / B =E A .(1-E B ) / ((1-E A ).E B ) E A E B This indicates the extraction rate of metal element A and metal element B (extraction rate E = the content of metal element in the resin after one extraction / the content of metal element in the initial aqueous phase × 100%).

[0059] Single-cycle attenuation rate = [(E n - E o ) / E o ] / n × 100%, where E o E n The phosphorus extraction rates are the initial and nth cycles, respectively.

[0060] In this application, the term "and / or" covers situations involving one or both of the mentioned elements.

[0061] In this application, the terms "comprising" and "including" cover situations where other elements not explicitly mentioned are also included, as well as situations where the mentioned elements constitute the entirety of the application.

[0062] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any discrepancy between the definitions of terms in this specification and their commonly understood meaning by one of ordinary skill in the art to which this invention pertains, the definitions set forth herein shall prevail.

[0063] Unless otherwise stated, all numerical values ​​for the amount of ingredients, temperature, time, etc., used in the specification and claims are to be understood as being modified by the term "about". Therefore, unless otherwise indicated, the numerical parameters set forth herein are approximate values ​​that can be varied to obtain the desired performance.

[0064] Example The following will further illustrate the concept, specific structure, and technical effects of the present invention with reference to embodiments, so as to enable those skilled in the art to fully understand the purpose, features, and effects of the present invention. It will be readily understood by those skilled in the art that the embodiments described herein are merely illustrative, and the scope of the present invention is not limited thereto.

[0065] Synthesis example 1 Weak acid cation exchange resin 1 (structure is as follows) was prepared according to the following description. (where M is polystyrene resin): Take 9.0 g (72 mmol) of taurine in a three-necked flask, add 7.2 mL (72 mmol) of formaldehyde solution and 7.9 g (72 mmol) of dimethyl phosphite, add 70 mL of water, and stir the mixture at 100 °C for 24 hours under nitrogen protection to obtain... intermediate, Then, 10g (50mmol) of the intermediate and chlorinated globulin resin (the preparation method of chlorinated globulin resin is described in CN101781379B, purchased from Zhejiang Zhengguang Industrial Co., Ltd.) were placed in a 100ml three-necked flask, and 60g of N,N-dimethylformamide and 7.27g (72mmol) of triethylamine were added sequentially. Under mechanical stirring, the mixture was heated to 50℃ and reacted for 8 hours. After the reaction was completed, the mixture was washed 3 times with anhydrous ethanol (50 mL each time) and 2 times with acetone (30 mL each time) until the filtrate was colorless, thus obtaining weak acid cation exchange resin 1.

[0066] Synthesis example 2 The weak acid cation exchange resin 2 (with the structure described below) was prepared according to the following method. (where M is polystyrene resin): 10 g (30 mmol, -NH2) of primary amino polystyrene microspheres (from Samsung Resin, model SX382) was placed in a 100 ml three-necked flask. 3.3 g (35 mmol) of chloroacetic acid and 3.7 g (35 mmol) of sodium carbonate were added, along with 50 mL of water. The mixture was heated at 80 °C for 12 hours under mechanical stirring to obtain intermediate resin 2-1.

[0067] Next, 3 mL (30 mmol) of formaldehyde solution and 2.45 g (30 mmol) of phosphorous acid were added to intermediate resin 2-1, along with 70 mL of water. The mixture was then reacted at 100 °C for 24 hours under mechanical stirring. After the reaction was completed, the resin was washed according to the method in Synthesis Example 1 to obtain weak acid cation exchange resin 2.

[0068] Synthesis example 3 Weak acid cation exchange resin 3 (structure is as follows) was prepared according to the following description. (where M is polystyrene resin): 10 g (30 mmol, -NH2) of primary amino polystyrene microspheres (from Samsung Resin, model SX382) was placed in a three-necked flask. 6.6 g (70 mmol) of chloroacetic acid and 7.4 g (70 mmol) of sodium carbonate were added, along with 50 mL of water. The mixture was heated at 80 °C for 12 hours under mechanical stirring. After the reaction was completed, the resin was washed according to the method in Synthesis Example 1 to obtain weak acid cation exchange resin 3.

[0069] Synthesis example 4 The weak acid cation exchange resin 4 (with the structure described below) was prepared according to the following method. (where M is polystyrene resin): 10 g (30 mmol, -NH2) of primary amino polystyrene microspheres (from Samsung Resin, model SX382) was placed in a three-necked flask. 11.4 g (57 mmol) of diethyl (2-ethylchloro) phosphate, 60 g of N,N-dimethylformamide and 2.88 g (72 mmol) of sodium hydroxide were added to the flask. The mixture was heated to 80 °C under mechanical stirring and reacted for 2 hours. After the reaction was completed, the resin was washed according to the method of Synthesis Example 1 to obtain weak acid cation exchange resin 4.

[0070] Synthesis example 5 The weak acid cation exchange resin 5 (with the structure described below) was prepared according to the following method. (where M is polystyrene resin): 10 g (30 mmol, -NH2) of primary amino polystyrene microspheres (from Samsung Resin, model SX382) was placed in a three-necked flask. 6 mL (60 mmol) of formaldehyde solution and 8.5 g (60 mmol) of phenylphosphine acid were added to the flask. 70 mL of water was added, and the mixture was reacted at 100 °C for 24 hours under mechanical stirring. After the reaction was completed, the resin was washed according to the method of Synthesis Example 1 to obtain weak acid cation exchange resin 5.

[0071] Synthesis example 6 Weak acid cation exchange resin 6 (structure is as follows) was prepared according to the following description. (where M is polystyrene resin): 10 g (30 mmol, -NH2) of primary amino polystyrene microspheres (from Samsung Resin, model SX382) was placed in a 100 ml three-necked flask. 3.8 g (40 mmol) of chloroacetic acid and 4.2 g (40 mmol) of sodium carbonate were added, along with 50 mL of water. The mixture was heated at 80 °C for 12 hours under mechanical stirring to obtain intermediate resin 6-1.

[0072] Next, 4.5 g (30 mmol) of N,N-diethyl-2-chloroacetamide and 3.2 g (30 mmol) of sodium carbonate were added to intermediate resin 6-1, along with 50 mL of water. The mixture was heated at 80 °C for 12 hours under mechanical stirring. After the reaction was completed, the resin was washed according to the method in Synthesis Example 1 to obtain weak acid cation exchange resin 6.

[0073] Example 1 (1) Resin pretreatment: Wash the weak acid cation exchange resin 1 with 0.25 mol / L sodium hydroxide solution until the supernatant pH > 10, then wash with deionized water until neutral (pH 7.0 ± 0.5) and set aside.

[0074] (2) Preparation of phosphorus adsorption resin: The pretreated weak acid cation exchange resin 1 was circulated through the resin bed with a ferric sulfate solution (0.20 mol / L, adjusted to pH 1.5 ± 0.1 with sulfuric acid) at a flow rate of 3.0 BV / h, with a circulation volume of 5 times the resin bed volume (5 BV), for 6 hours. After the reaction was completed, the resin bed was washed with deionized water at a flow rate of 2.0 BV / h, with a washing volume of 5 BV, finally yielding phosphorus adsorption resin 1.

[0075] (3) Phosphorus extraction and back-extraction The phosphogypsum percolate (components shown in Table 1, pH 1.7) was passed from bottom to top through an adsorption column (20.0 ± 0.5 °C) at a flow rate of 3.0 BV / h. The volume of the phosphogypsum percolate was 12 BV. The raffinate was then added to the phosphogypsum percolate for further extraction. This extraction cycle was repeated for 5 h to obtain the loaded resin. The loaded resin was washed with deionized water and then back-extracted with 2.0 mol / L H2SO4 (1.0 BV / h) at a flow rate of 2.0 BV / h. The washing volume was 5.0 BV, and the back-extraction volume was 1 BV. The back-extracted liquid was then used to back-extract the adsorption column obtained under the same extraction conditions. This process was repeated 4 times.

[0076] Table 1. Concentration of major ions in phosphogypsum leachate (g / L) Note: The ICP-OES measurement value is the total phosphorus content.

[0077] The concentrations of each component in the obtained back-extraction solution are shown in Table 3. The contents of Fe and P are 17235.3 mg / L and 6246.1 mg / L, respectively, and the content of Ca is 20.1 mg / L. The iron-to-calcium ratio is 857, which can be used to prepare battery-grade iron phosphate (CaFe). 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron Phosphate for Batteries".

[0078] Example 2 Weak acid cation exchange resin 1 was replaced with weak acid cation exchange resin 2, the pH of the phosphogypsum leachate was 1.9 (components are shown in Table 2), and the other conditions were the same as in Example 1.

[0079] Table 2 Content of major components in phosphogypsum leachate The concentrations of each component in the obtained back-extraction solution are shown in Table 3. The contents of Fe and P are 23298.7 mg / L and 8848.7 mg / L, respectively, and the content of Ca is 14.8 mg / L. The iron-to-calcium ratio is 1574, which can be used to prepare battery-grade iron phosphate (CaFe). 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron Phosphate for Batteries".

[0080] Example 3 Replace weak acid cation exchange resin 1 with weak acid cation exchange resin 3, and keep the other conditions the same as in Example 1.

[0081] The concentrations of each component in the obtained back-extraction solution are shown in Table 3. The contents of Fe and P are 21326.5 mg / L and 7820.6 mg / L, respectively, and the content of Ca is 18.3 mg / L. The iron-to-calcium ratio is 1165, which can be used to prepare battery-grade iron phosphate (CaFe). 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron Phosphate for Batteries".

[0082] Example 4 Weak acid cation exchange resin 1 was replaced with weak acid cation exchange resin 4, and the ferric sulfate solution (0.20 mol / L, pH 1.5±0.1) was replaced with a mixed solution of ferric chloride and ferric citrate (total iron concentration 0.20 mol / L, FeCl3:ferric citrate molar ratio 1:1, pH adjusted to 1.0±0.1 with sulfuric acid). The remaining conditions were the same as in Example 1.

[0083] The concentrations of each component in the obtained back-extraction solution are shown in Table 3. The contents of Fe and P are 20743.8 mg / L and 7464.3 mg / L, respectively, and the content of Ca is 3.04 mg / L. The iron-to-calcium ratio is 68:24, which can be used to prepare battery-grade iron phosphate (CaFe). 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron Phosphate for Batteries".

[0084] Example 5 Replace weak acid cation exchange resin 1 with weak acid cation exchange resin 5. The weak acid cation exchange resin 5 is directly circulated through the resin bed with ferric nitrate solution (0.45 mol / L, adjusted to pH 1.8±0.1 with nitric acid) at a flow rate of 3.0 BV / h. The subsequent operation is the same as in Example 1 except that the pretreatment step is omitted.

[0085] The concentrations of each component in the obtained back-extraction solution are shown in Table 3. The contents of Fe and P are 22111.6 mg / L and 8183.5 mg / L, respectively, and the content of Ca is 15.3 mg / L. The iron-to-calcium ratio is 14:45, which can be used to prepare battery-grade iron phosphate (CaFe). 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron Phosphate for Batteries".

[0086] Example 6 Replace weak acid cation exchange resin 1 with weak acid cation exchange resin 6, and keep the other conditions the same as in Example 1.

[0087] The concentrations of each component in the obtained back-extraction solution are shown in Table 3. The contents of Fe and P are 19622.7 mg / L and 7095.2 mg / L, respectively, and the content of Ca is 14.2 mg / L. The iron-to-calcium ratio is 1382, which can be used to prepare battery-grade iron phosphate (CaFe). 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron Phosphate for Batteries".

[0088] Example 7 The pH of the phosphogypsum leachate was adjusted to 0.8 using sulfuric acid solution, and the other conditions were the same as in Example 2.

[0089] The concentrations of each component in the obtained back-extraction solution are shown in Table 3. The contents of Fe and P are 22941.9 mg / L and 8502.4 mg / L, respectively, and the content of Ca is 13.3 mg / L. The iron-to-calcium ratio is 17:25, which can be used to prepare battery-grade iron phosphate (CaFe). 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron Phosphate for Batteries".

[0090] Example 8 The pH of the phosphogypsum leachate was adjusted to 2.5 using sodium hydroxide solution. Weak acid cation exchange resin 1 was replaced with weak acid cation exchange resin 5, and the other conditions were the same as in Example 3.

[0091] The concentrations of each component in the obtained back-extraction solution are shown in Table 3. The contents of Fe and P are 22198.2 mg / L and 8199.6 mg / L, respectively, and the content of Ca is 23.9 mg / L. The iron-to-calcium ratio is 9:29, which can be used to prepare battery-grade iron phosphate (CaFe). 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron Phosphate for Batteries".

[0092] Example 9 The pH of the phosphogypsum leachate was adjusted to 3.0 using sodium hydroxide solution, and the loaded resin was washed with H2SO4 at pH 1.5. The remaining conditions were the same as in Example 3.

[0093] The concentrations of each component in the obtained back-extraction solution are shown in Table 3. The contents of Fe and P are 21273.2 mg / L and 7801.5 mg / L, respectively, and the content of Ca is 17.9 mg / L. The iron-to-calcium ratio is 1188, which can be used to prepare battery-grade iron phosphate (CaFe). 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron Phosphate for Batteries".

[0094] Comparative Example 1 Replace the weak acid cation exchange resin 1 with the structure of [structure not provided]. The resin, wherein M is polystyrene resin, and the other conditions are the same as in Example 1.

[0095] The concentrations of each component in the obtained back-extraction solution are shown in Table 3. The contents of Fe and P are 23196.9 mg / L and 8753.4 mg / L, respectively, the content of Ca is 87.8 mg / L, and the iron-calcium ratio is 264. Compared with the phosphorus adsorption resin in Example 1, the iron-calcium ratio is 92.8% lower.

[0096] Table 3. Concentrations of each component in the back-extraction solution (mg / L) Note: The data are the average of three parallel experiments, and the relative standard deviation (RSD) is <5%.

[0097] Table 3 shows that the weak acid cation exchange resin 4 performed best, with the Ca in the back-extraction solution being the lowest. 2+ It was only 3.04 mg / L, a 96.5% decrease compared to control 1 (87.8 mg / L), and the iron-calcium ratio (6824) was 24.8 times higher than control 1 (264).

[0098] Example 10 (1) Adsorption experiment: Take 1 g of phosphorus adsorption resin 1-6 (prepared from weak acid cation exchange resin 1-6 according to Example 1), add 25 mL of phosphogypsum filtrate (components are shown in Table 1, pH is 1.7), shake at 25±0.5℃ for 12 h and then separate solid and liquid. The rotation speed is 150 rpm. The concentration of P in the raffinate is determined by ICP-OES and the removal rate is calculated (Table 4).

[0099] (2) Cyclic stability test: The phosphorus-loaded resin was washed with 75 mL of deionized water, back-extracted three times with 2.0 mol / L H2SO4 (25 mL each time), and washed until neutral. The solution was reused 10 times. The decay of P removal rate after the 10th cycle was measured.

[0100] (3) Dissolution test: Take 1 g of resin after 10 cycles, add 20 mL of H2SO4 solution with pH 1.5 or 0.8, and shake at 25±0.5℃ and 150 rpm for 30 min. After filtration, determine Fe by ICP-OES. 3+ Concentration (Table 5), method detection limit 0.02 mg / L.

[0101] Comparative Example 2 Ferric sulfate was replaced with an equal volume of deionized water, and weak acid cation exchange resin 3 was used as unmodified resin 3. Performance tests were conducted with reference to Example 10. The difference from Example 10 was that the phosphorus adsorption resin was replaced with unmodified resin 3. The P removal rates are shown in Table 4. Comparative Example 3 After pretreatment of the weak acid cation exchange resin 3 according to Example 1, it was circulated through the resin bed with an aluminum sulfate solution (0.20 mol / L, adjusted to pH 1.5±0.1 with sulfuric acid) at a flow rate of 3.0 BV / h, with a circulation volume of 5 times the resin bed volume (5 BV), for 6 hours. After the reaction was completed, the resin bed was washed with deionized water at a flow rate of 2.0 BV / h, with a washing volume of 5 BV, finally obtaining the aluminum-modified resin. Performance testing was performed according to Example 10. The difference from Example 10 was that the phosphorus adsorption resin was replaced with the aluminum-modified resin. The phosphorus removal rate is shown in Table 4.

[0102] Comparative Example 4 After pretreatment of the weak acid cation exchange resin 3 according to Example 1, it was circulated through the resin bed with a lanthanum nitrate solution (0.20 mol / L, adjusted to pH 1.5±0.1 with nitric acid) at a flow rate of 3.0 BV / h, with a circulation volume of 5 times the resin bed volume (5 BV), for 6 hours. After the reaction was completed, the resin bed was washed with deionized water at a flow rate of 2.0 BV / h, with a washing volume of 5 BV, finally obtaining the lanthanum modified resin. Performance testing was performed according to Example 10. The difference from Example 10 was that the phosphorus adsorption resin was replaced with the lanthanum modified resin. The phosphorus removal rate is shown in Table 4.

[0103] Table 4 Extraction performance of each element by each resin Table 5 Results of Metal Ion Dissolution Test As shown in Table 4, the phosphorus adsorption resin of this invention has a P removal rate ≥95.0% (compared to only 37.8% or 81.3% for aluminum / lanthanum modified resins), and a Ca removal rate of ≥95.0%. 2+ Co-adsorption ≤20% (9.8% or 12.6% for aluminum / lanthanum modified resin), SO4 2- Adsorption rate ≤5% (5.8% or 6.8% for aluminum / lanthanum modified resin). P / Ca 2+ The selectivity coefficient reached 987 (comparative examples 2-4 were all <50).

[0104] After 10 cycles, the phosphorus removal rate of phosphorus adsorption resin 3 decreased from 96.0% to 90.4% (an absolute decrease of 5.6 percentage points, with a capacity retention of 94.2%); the lanthanum-modified resin decreased from 81.3% to 54.5% (an decrease of 26.8 percentage points, with a capacity retention of 67.0%). The single-cycle degradation rate of phosphorus adsorption resin 3 (0.56%) was only 1 / 4.8 of that of the lanthanum-modified resin (2.68%).

[0105] Table 5 shows that, in a simulated acidic environment with a pH of 1.5, the Fe content of phosphorus adsorption resins (resins 1-6) is... 3+The leaching amount (0.09-0.17 mg / L) is reduced by 96.8%-98.7% compared with aluminum / lanthanum modified resin.

[0106] Under more stringent conditions at pH 0.8, the Fe of phosphorus adsorption resin 1... 3+ The dissolution amount was still <0.2 mg / L, further verifying its structural stability under extreme acidic conditions.

[0107] The foregoing descriptions are merely exemplary embodiments or examples of the present invention and are not intended to limit the invention. Those skilled in the art will recognize that the present invention can be modified and varied in many ways. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention are included within the scope of the claims of this application.

Claims

1. The use of a phosphorus adsorption resin for selectively adsorbing phosphorus from phosphorus-containing wastewater, characterized in that: The phosphorus adsorption resin comprises a weak acid cation exchange resin and Fe supported on its surface. 3+ The phosphorus-containing wastewater has a pH of 0.8-3.0, a phosphorus concentration of 0.1-5 g / L, and also contains 0.1-1 g / L of Ca; the preparation method of the phosphorus adsorption resin includes the following steps: i) A weak acid cation exchange resin is reacted with an iron salt solution, wherein the iron salt solution is selected from one or more of ferric sulfate, ferric chloride, ferric nitrate, ferric citrate, and ferric tartrate; ii) After the reaction is complete, solid-liquid separation is performed to obtain supported Fe. 3+ Phosphorus adsorption resin, The weak acid cation exchange resin comprises resins of formula (I) and / or formula (II): (AND) (II) in: M is the base resin, R1 is selected from the following groups: , , , , , or , R2 is selected from hydrogen or the following groups: , , , , , , , , , , , , , , , , , or , R3 is selected from the following groups: , , , , , , , , or , R4 is selected from hydrogen or the following groups: , , , , , , , , , or ,in This is the connection site between the group and A or N. A is -N- or -N((CH2) n NH-)2, where n is an integer from 2 to 9, Ph stands for phenyl.

2. The use according to claim 1, characterized in that, M is selected from one of polystyrene resin, copolymer of styrene and divinylbenzene, phenolic resin, polyacrylic resin, and silicone resin.

3. The use according to claim 2, characterized in that, M is selected from polystyrene resin or copolymer of styrene and divinylbenzene.

4. The use according to claim 1, characterized in that, The weak acid cation exchange resin is a macroporous resin with a pore size of 10-1000 nm.

5. The use according to claim 1, characterized in that, Fe 3+ The concentration is 0.01-1.20 mol / L, and the initial pH of the iron salt solution is 0.5-2.

3.

6. The use according to claim 1, characterized in that, Phosphorus-containing wastewater also contains Al 0.1-5 g / L.

7. A method for selectively adsorbing phosphorus from phosphorus-containing wastewater, characterized in that, Includes the following steps: (a) The phosphorus adsorption resin according to any one of claims 1-6 is contacted with phosphorus-containing wastewater for extraction, and the phosphorus adsorption resin loaded with phosphorus is recovered by solid-liquid separation after extraction. (b) The phosphorus-loaded phosphorus adsorption resin is washed and back-extracted sequentially using a detergent and a back-extracting agent to obtain a phosphorus-enriched back-extracting solution and a back-extracted phosphorus adsorption resin.

8. The method according to claim 7, characterized in that, The extraction flow rate is 0.1-10 BV / h, and the temperature is 10-80℃; the number of back-extraction stages is 1-10, and the back-extraction flow rate is 0.5-5 BV / h.

9. The method according to claim 7 or 8, characterized in that, The detergent is deionized water or an acidic solution with a pH of 0.5-6.0, and the stripping agent is 0.5-4 mol / L sulfuric acid.

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