Application and method of phosphorus adsorption resin for selectively adsorbing phosphorus from phosphorus-containing wastewater

Abstract

The invention relates to application and a method of phosphorus adsorption resin for selectively adsorbing phosphorus from phosphorus-containing wastewater. The phosphorus adsorption resin comprises weak acid cation exchange resin and Fe < 3 + > loaded on the surface of the weak acid cation exchange resin; the pH value of the phosphorus-containing wastewater is 0.8-3.0, the phosphorus concentration is 0.1-5 g / L, and the wastewater further contains 0.1-1 g / L of Ca; the phosphorus adsorption resin is prepared by the following steps: i) carrying out contact reaction on weak acid cation exchange resin and a ferric salt solution, wherein the ferric salt is selected from one or more of ferric sulfate, ferric chloride, ferric nitrate, ferric citrate and ferric tartrate; and ii) after the reaction is completed, carrying out solid-liquid separation to obtain the Fe < 3 + >-loaded phosphorus adsorption resin. According to the method, high-selectivity adsorption (larger than or equal to 95%) of phosphorus can be achieved, the phosphorus and calcium separation effect is good, the iron-calcium ratio in the phosphorus-enriched strip liquor is larger than or equal to 800, and the method can be used for preparing battery-grade iron phosphate.

Description

Technical Field

[0001] The present invention relates to the field of wastewater treatment, and in particular to a use and method of a phosphorus adsorption resin for selectively adsorbing phosphorus from phosphorus-containing wastewater. Background Art With the discharge of industrial wastewater, agricultural runoff, and domestic sewage, excessive phosphorus levels in water bodies have become one of the main causes of eutrophication. Traditional phosphorus removal methods (such as chemical precipitation and biological treatment) are subject to high costs, low efficiency, and the risk of secondary pollution. For example, chemical precipitation requires the addition of large amounts of aluminum or iron salts, which not only increases sludge volume but also may leave residual metal ions. Biological treatment methods, on the other hand, require stringent operating conditions and offer inconsistent phosphorus removal results.

[0002] In recent years, adsorption has attracted widespread attention due to its advantages such as ease of operation, cost control, and environmental friendliness. While existing adsorbents have some phosphorus removal effects, they suffer from poor selectivity for phosphorus and impurity elements (especially calcium).

[0003] Therefore, developing a highly selective adsorption method to solve the problem of poor selectivity between phosphorus and impurity elements (especially calcium) in the prior art has important environmental and economic value. Summary of the Invention

[0004] An object of the present invention is to provide an adsorption method capable of selectively adsorbing phosphorus.

[0005] Therefore, according to the first aspect, the present invention provides a 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 3+ The pH value of the phosphorus-containing wastewater is 0.8-3.0, the phosphorus concentration is 0.1-5 g / L, and the wastewater also contains Ca 0.1-1 g / L; the preparation method of the phosphorus adsorption resin comprises the following steps: i) contacting a weak acid cation exchange resin with an iron salt solution for reaction, 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 completed, solid-liquid separation is performed to obtain the loaded Fe 3+ Phosphorus adsorption resin.

[0006] According to a second aspect, the present invention provides a method for selectively adsorbing phosphorus from phosphorus-containing wastewater, comprising the following steps: (a) contacting the phosphorus adsorption resin with phosphorus-containing wastewater for extraction, and recovering the phosphorus-loaded phosphorus adsorption resin by solid-liquid separation after the extraction is completed; (b) washing and stripping the phosphorus-loaded phosphorus adsorption resin with a detergent and a stripping agent in sequence to obtain a phosphorus-enriched stripping solution and a stripped phosphorus adsorption resin.

[0007] The method of the present invention can achieve high selective adsorption of phosphorus (≥95%), has good separation effect of phosphorus and calcium, and the iron-calcium ratio in the phosphorus-enriched stripping solution is ≥800, which can be used to prepare battery-grade iron phosphate. DETAILED DESCRIPTION

[0008] Various aspects of the invention as well as further objects, features and advantages will appear more fully hereinafter.

[0009] Uses of phosphorus adsorption resins According to a first aspect, the present invention provides a 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 3+ The pH value of the phosphorus-containing wastewater is 0.8-3.0, the phosphorus concentration is 0.1-5 g / L, and the wastewater also contains Ca 0.1-1 g / L; the preparation method of the phosphorus adsorption resin comprises the following steps: i) contacting a weak acid cation exchange resin with an iron salt solution for reaction, 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 completed, solid-liquid separation is performed to obtain the loaded Fe 3+ Phosphorus adsorption resin.

[0010] Preferably, the weak acid cation exchange resin comprises a resin of formula (I) and / or formula (II): (I) (II) in: M is the base resin, R1 is -CH(COR5)2 or -(CH2) q COR6, R2 is hydrogen, -CH(COR5)2, -(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, n is an integer of 2-9, R3 is -CH2P(O)(OH)(Ph), -CH2P(O)(OH)2 or -(CH2) yP(O)(R7)2, R4 is hydrogen, -CH2P(O)(OH)(Ph), -(CH2) y P(O)(R7)2 or -(CH2) t SO3H, R5 is selected from hydroxy, optionally halogenated C 1- C 10 Alkoxy, optionally C1-C 10 an alkyl or halogen-substituted amino group, R6 is selected from hydroxy, optionally halogenated C 1- C 10 Alkoxy, optionally C1-C 10 an alkyl or halogen-substituted amino group, R7 is selected from phenyl or optionally halogenated C 1- C 10 Alkoxy, y, t and q are any integers from 1 to 9, Ph is phenyl, and halogen is Cl or Br.

[0011] The present invention has no particular limitation on M, and preferably, M is selected from polystyrene resin, a copolymer of styrene and divinylbenzene, a phenolic resin, a polyacrylic resin, and a silicon-based resin. More preferably, M is selected from polystyrene resin and a copolymer of styrene and divinylbenzene.

[0012] Preferably, R5 is selected from hydroxy, optionally halogenated C 1- C8 alkoxy, amino optionally substituted by C1-C8 alkyl or halogen.

[0013] Preferably, R6 is selected from hydroxy, optionally halogenated C 1- C8 alkoxy, amino optionally substituted by C1-C8 alkyl or halogen.

[0014] 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.

[0015] Preferably, R1 is selected from the following groups: 、 、 、 、 、 or ,in It is the connection site between the group and N.

[0016] Preferably, R2 is selected from hydrogen and the following groups: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 or , in It is the connection site between the group and N.

[0017] Preferably, R3 is selected from the following groups: 、 、 、 、 、 、 、 、 or , in It is the connection site between the group and A.

[0018] Preferably, R4 is selected from hydrogen and the following groups: 、 、 、 、 、 、 、 、 、 or ,in It is the connection site between the group and A.

[0019] Preferably, the weak acid cation exchange resin has a structure selected from the following: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 or , Wherein M is selected from polystyrene resin, copolymer of styrene and divinylbenzene.

[0020] More preferably, the weak acid cation exchange resin has a structure selected from the following: 、 、 、 、 or , Wherein M is selected from polystyrene resin, copolymer of styrene and divinylbenzene.

[0021] Preferably, the weak acid cation exchange resin is a macroporous resin.

[0022] As used herein, the pore size of a macroporous resin is in the range of 10-1000 nm, preferably, 20-100 nm.

[0023] The weak acid cation exchange resin can be prepared by a method comprising the following steps: S11, reacting a primary amine resin with a molar ratio of 1: 0.75-1.75, preferably 1: 0.8-1.5, to a compound of formula III, IV or V 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, wherein the solute of the alkaline solution is one or a combination of two or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, ammonia water, triethylamine and calcium hydroxide, and the solvent of the alkaline solution is one or a combination of two or more of water, ethanol, methanol and N,N-dimethylformamide, the ratio of the amount of the solute in the alkaline solution to the molar amount of the primary amine group in the resin is 0.8-2.5:1, and the amount of the solvent is 1-30 times the mass of the resin; S12. Reacting the intermediate resin with a phosphorus-containing substance of formula Va, Vb or Vc in an acidic solution or aqueous solution having a concentration of 0.1-6 mol / L in the presence of formaldehyde at a temperature of 40-120° C. for 4-48 h to obtain the resin of formula (I), wherein the solvent in the acidic solution is a mixture of one or more of water, ethanol, methanol, and N,N-dimethylformamide, the ratio of the amount of acid in the acidic solution to the molar amount of primary amine groups in the resin is 0.5-3:1, and the ratio of the molar amount of primary amine groups in the resin matrix to formaldehyde to the 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 H2N-(CH2) n -NH-(CH2) n -NH2 and a compound of formula V in a molar ratio of 1.1-1.5:1, or A substitution reaction is performed to obtain an intermediate of formula Vd, and then a chlorine ball resin is reacted with the intermediate of formula Vd at a molar feed ratio of 1:(1.2-3) to obtain the resin of formula (II)), wherein the compound V is as defined for step S11, and the reaction conditions of the chlorine ball resin and the intermediate of formula Vd are as described for step S11. (Vd) or, S31, in acidic or aqueous solution in the presence of formaldehyde to make H2N-(CH2) q -C(O)R6 or H2N-(CH2) t -SO3H reacts with the phosphorus-containing substance of formula Va, Vb or Vc at a temperature of 40-120°C to obtain an intermediate compound, wherein the phosphorus-containing substance of formula Va or Vb and the reaction conditions are as described for step S12; then, chlorine ball resin is reacted with the intermediate compound at a molar feed 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 equal to that of H2N-(CH2) q -C(O)R6 or H2N-(CH2) t -SO3H molar ratio is 0.5-3:1, the H2N-(CH2) q -C(O)R6 or H2N-(CH2) t The molar ratio of -SO3H, formaldehyde and the phosphorus-containing substance 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 ball resin and the intermediate compound are the same as those described for step S21. or, S41, make H2N-(CH2) t-SO3H and the compound of formula IV are 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. The compound IV and the reaction conditions are as described for step S11 to obtain an intermediate compound. Then, a chlorine ball resin is reacted with the intermediate compound at a molar feed ratio of 1:(1.2-3) to obtain the resin of formula (I). The reaction conditions of the chlorine ball resin and the intermediate compound are as described for step S21. R3 is as defined for Formula II, R5 is as defined for formula I, R6 is as defined for Formula I, R7 is as defined for Formula II, y, t, q, n are as defined for Formula I or Formula II, X = Cl, Br or I.

[0024] Before steps S11, S12, S21, S31, and S41, the resin matrix may be pretreated, with specific reference to the resin pretreatment in patent application No. 2023116291434.

[0025] The "chlorospherical resin" described in this application refers to a resin containing a chloromethyl (-CH2Cl) functional group.

[0026] Preferably, before step i), the weak acid cation exchange resin is washed with 0.25-8 mol / L, preferably 0.25-1.25 mol / L, sodium hydroxide or potassium hydroxide solution until the supernatant is alkaline, and then the resin is washed with deionized water until neutral and filtered for later use.

[0027] Preferably, the iron salt solution is ferric sulfate solution.

[0028] Preferably, after solid-liquid separation, the phosphorus adsorption resin is washed with water to remove entrained iron salt solution.

[0029] 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.

[0030] 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.

[0031] Preferably, the reaction flow rate is 1-30 BV / h, more preferably, 1-5 BV / h.

[0032] Preferably, the reaction time is 1-30 h, more preferably 2-6 h.

[0033] Preferably, the reaction volume of the iron salt solution is 2-8 BV, more preferably 3-5 BV.

[0034] Preferably, the initial pH of the iron salt solution is 0.5-2.3, more preferably, 0.8-2.0.

[0035] Preferably, the water used for washing can be deionized water, system recycled water, or MVR condensation recycled water.

[0036] Preferably, the pH of the phosphorus-containing wastewater is 1-2.5, more preferably, 1.5-2.

[0037] Preferably, the phosphorus concentration of the phosphorus-containing wastewater is 0.1-4 g / L.

[0038] Furthermore, phosphorus-containing wastewater also contains Al 0.1-5 g / L.

[0039] Preferably, the phosphorus is present as a mixture of one or more of phosphate, monohydrogen phosphate and dihydrogen phosphate.

[0040] The phosphorus-containing wastewater can be a mixture of one or more of phosphogypsum leachate, washing water of iron phosphate washing products, phosphorus-containing liquid in lithium iron phosphate pre-extraction, and industrial phosphorus-containing wastewater.

[0041] According to a second aspect, the present invention provides a method for selectively adsorbing phosphorus from phosphorus-containing wastewater, comprising the following steps: (a) contacting the phosphorus adsorption resin with phosphorus-containing wastewater for extraction, and recovering the phosphorus-loaded phosphorus adsorption resin by solid-liquid separation after the extraction is completed; (b) washing and stripping the phosphorus-loaded phosphorus adsorption resin with a detergent and a stripping agent in sequence to obtain a phosphorus-enriched stripping solution and a stripped phosphorus adsorption resin.

[0042] Preferably, the extraction flow rate is 0.1-10 BV / h, more preferably, the extraction flow rate is 0.1-5 BV / h.

[0043] The extraction device can be, for example, a continuous ion exchange resin column or a valve array resin column.

[0044] The resin column can be, for example, a fluidized bed or a fixed bed.

[0045] When the resin is in a fluidized bed, preferably, the fluid flows in a direction perpendicular to the ground from bottom to top.

[0046] Preferably, the extraction temperature is 10-80°C, more preferably, the extraction temperature is 20-50°C.

[0047] Preferably, the detergent is deionized water and / or an acid solution, more preferably, an acid solution.

[0048] Preferably, the acid solution is one of hydrochloric acid, sulfuric acid, and nitric acid solutions, or a combination of at least two thereof. More preferably, the acid solution is sulfuric acid solution.

[0049] Preferably, the pH of the acid solution is 0.5-6.0, more preferably, 0.8-2.0.

[0050] Preferably, the flow rate of the washing process is 0.5-5 BV / h.

[0051] Preferably, the wash volume is 1-10 BV.

[0052] Preferably, the stripping agent is 0.5-4 mol / L sulfuric acid.

[0053] Preferably, the stripping flow rate is 0.5-5 BV / h.

[0054] Preferably, the number of stripping stages is 1-10, and the resin columns are connected in series and / or in parallel.

[0055] Preferably, the volume of a single column stripping is 0.2-10 BV, more preferably 1-5 BV.

[0056] The method of the present invention can achieve high selective adsorption of phosphorus (≥95%), has good separation effect of phosphorus and calcium, and the iron-calcium ratio in the phosphorus-enriched stripping solution is ≥800, which can be used to prepare battery-grade iron phosphate.

[0057] The "selectivity" of the present invention is represented by the separation coefficient β of the metal elements. Further, the separation coefficient is obtained by the following formula: β A / B =E A .(1-E B ) / ((1-E A ).E B ) E A 、E B It represents the extraction rate of metal element A and metal element B (extraction rate E = the content of metal elements in the resin after one extraction is completed / the content of metal elements in the initial aqueous phase 100%).

[0058] Single decay rate = [(E n -E o ) / E o ] / n × 100%, where E o 、E n are the phosphorus extraction rates of the initial and nth cycles, respectively.

[0059] In this application, the term "and / or" encompasses situations involving either or both of the mentioned elements.

[0060] In the present application, the terms “comprise” and “include” encompass the case where the phrases “comprise” and “include” also include or comprise other elements not explicitly mentioned as well as the case where the phrases are composed of the mentioned elements.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. When the definition of a term in this specification conflicts with the meaning commonly understood by those skilled in the art to which the present invention belongs, the definition described in this article shall prevail.

[0062] Unless otherwise indicated, all numbers expressing amounts of ingredients, temperatures, times, and so forth used in the specification and claims are to be understood as being modified by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth herein are approximations that can vary depending upon the desired properties sought to be obtained.

[0063] Example The following will further illustrate the concept, specific structure and technical effects of the present invention in conjunction with the embodiments, so that those skilled in the art can 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 herein are for illustrative purposes only and the scope of the present invention is not limited thereto.

[0064] Synthesis example 1 Weakly acidic cation exchange resin 1 (structure: , wherein M is a polystyrene resin): 9.0 g (72 mmol) of taurine was placed in a three-necked flask, 7.2 mL (72 mmol) of formaldehyde solution and 7.9 g (72 mmol) of dimethyl phosphite were added, and 70 mL of water was added. The mixture was stirred at 100 ° C under nitrogen protection for 24 hours to obtain intermediates, Then, 10 g (50 mmol) of the intermediate and chlorinated ball resin (the preparation method of chlorinated ball resin is described in CN101781379B and purchased from Zhejiang Zhengguang Industrial Co., Ltd.) were placed in a 100 ml three-necked flask, and 60 g of N,N-dimethylformamide and 7.27 g (72 mmol) of triethylamine were added in sequence. Under mechanical stirring, the mixture was heated to 50° C. and reacted for 8 hours. After the reaction, the mixture was washed with anhydrous ethanol 3 times (50 mL each time) and acetone 2 times (30 mL each time) until the filtrate was colorless to obtain weak acid cation exchange resin 1.

[0065] Synthesis example 2 Weakly acidic cation exchange resin 2 (structure: , wherein M is a 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, and 50 mL of water was added. The mixture was heated at 80°C with mechanical stirring for 12 hours to obtain the intermediate resin 2-1.

[0066] Next, 3 mL (30 mmol) of formaldehyde solution and 2.45 g (30 mmol) of phosphorous acid were added to the intermediate resin 2-1, and 70 mL of water was added. The mixture was reacted at 100° C. for 24 hours under mechanical stirring. After the reaction, the resin was washed according to the method of Synthesis Example 1 to obtain weak acid cation exchange resin 2.

[0067] Synthesis example 3 Weakly acidic cation exchange resin 3 (structure: , wherein M is a polystyrene resin): Take 10 g (30 mmol, -NH2) of primary amino polystyrene microspheres (from Samsung resin, model SX382) in a three-necked flask, add 6.6 g (70 mmol) of chloroacetic acid and 7.4 g (70 mmol) of sodium carbonate, add 50 mL of water, and heat at 80°C under mechanical stirring for 12 hours. After the reaction is completed, the resin is washed according to the method of Synthesis Example 1 to obtain weak acid cation exchange resin 3.

[0068] Synthesis example 4 Weakly acidic cation exchange resin 4 (structure: , wherein M is a polystyrene resin): Take 10 g (30 mmol, -NH2) of primary amino polystyrene microspheres (from Samsung resin, model SX382) in a three-necked flask, add 11.4 g (57 mmol) of diethyl (2-ethyl chloride) phosphate, 60 g of N,N-dimethylformamide and 2.88 g (72 mmol) of sodium hydroxide, heat to 80°C under mechanical stirring, and react for 2 hours. After the reaction is completed, the resin is washed according to the method of Synthesis Example 1 to obtain weak acid cation exchange resin 4.

[0069] Synthesis example 5 Weakly acidic cation exchange resin 5 (structure: , wherein M is a polystyrene resin): Take 10 g (30 mmol, -NH2) of primary amino polystyrene microspheres (from Samsung resin, model SX382) in a three-necked flask, add 6 mL (60 mmol) of formaldehyde solution and 8.5 g (60 mmol) of phenylphosphinic acid, add 70 mL of water, and react at 100°C under mechanical stirring for 24 hours. After the reaction is completed, the resin is washed according to the method of Synthesis Example 1 to obtain weak acid cation exchange resin 5.

[0070] Synthesis example 6 Weakly acidic cation exchange resin 6 (structure: , wherein M is a 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 thereto. 50 mL of water was added and the mixture was heated at 80°C with mechanical stirring for 12 hours to obtain the intermediate resin 6-1.

[0071] Next, 4.5 g (30 mmol) of N,N-diethyl-2-chloroacetamide and 3.2 g (30 mmol) of sodium carbonate were added to the intermediate resin 6-1, and 50 mL of water was added. The mixture was heated at 80° C. for 12 hours under mechanical stirring. After the reaction, the resin was washed according to the method of Synthesis Example 1 to obtain weak acid cation exchange resin 6.

[0072] Example 1 (1) Resin pretreatment: The weak acid cation exchange resin 1 was washed with 0.25 mol / L sodium hydroxide solution until the pH of the supernatant was greater than 10, and then washed with deionized water until the pH was neutral (7.0±0.5), and then set aside.

[0073] (2) Preparation of phosphorus adsorption resin: Pretreated weak acid cation exchange resin 1 was circulated with ferric sulfate solution (0.20 mol / L, adjusted to pH 1.5 ± 0.1 with sulfuric acid) through the resin bed at a flow rate of 3.0 BV / h (5 BV) for 6 hours. After the reaction, the resin bed was washed with deionized water at a flow rate of 2.0 BV / h (5 BV) to obtain phosphorus-adsorbing resin 1.

[0074] (3) Phosphorus extraction and stripping Phosphogypsum leachate (composition shown in Table 1, pH 1.7) was passed through the adsorption column (20.0±0.5℃) from bottom to top at a flow rate of 3.0 BV / h. The volume of the phosphogypsum leachate was 12 BV. The raffinate was incorporated into the phosphogypsum leachate for further extraction. The extraction cycle was repeated for 5 h to obtain a loaded resin. The loaded resin was washed with deionized water and then stripped with 2.0 mol / L H2SO4 (1.0 BV / h). The washing flow rate was 2.0 BV / h, the washing volume was 5.0 BV, and the stripping liquid volume was 1 BV. The stripping liquid was then stripped on the adsorption column obtained under the same extraction conditions and reused four times.

[0075] Table 1 Main ion concentrations of phosphogypsum leachate (g / L) Note: The value determined by ICP-OES is the total phosphorus content.

[0076] The concentrations of the components in the stripping solution are shown in Table 3. The contents of Fe and P are 17235.3 mg / L and 6246.1 mg / L, respectively. The Ca content is 20.1 mg / L, and the iron-calcium ratio is 857. It can be used to prepare battery-grade iron phosphate (Ca 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron phosphate for batteries").

[0077] Example 2 The weak acid cation exchange resin 1 was replaced by the 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.

[0078] Table 2 Contents of main components of phosphogypsum leachate The concentrations of the components in the stripping solution are shown in Table 3. The contents of Fe and P are 23298.7 mg / L and 8848.7 mg / L, respectively. The Ca content is 14.8 mg / L, and the iron-calcium ratio is 1574. It can be used to prepare battery-grade iron phosphate (Ca 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron phosphate for batteries").

[0079] Example 3 The weak acid cation exchange resin 1 was replaced by the weak acid cation exchange resin 3, and the other conditions were the same as those in Example 1.

[0080] The concentrations of the components in the stripping solution are shown in Table 3. The contents of Fe and P are 21326.5 mg / L and 7820.6 mg / L, respectively. The Ca content is 18.3 mg / L, and the iron-calcium ratio is 1165. It can be used to prepare battery-grade iron phosphate (Ca 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron phosphate for batteries").

[0081] Example 4 The weak acid cation exchange resin 1 was replaced with the 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, adjusted to pH 1.0±0.1 with sulfuric acid). The other conditions were the same as in Example 1.

[0082] The concentrations of the components in the stripping solution are shown in Table 3. The contents of Fe and P are 20743.8 mg / L and 7464.3 mg / L, respectively. The Ca content is 3.04 mg / L, and the iron-calcium ratio is 6824. It can be used to prepare battery-grade iron phosphate (Ca 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron phosphate for batteries").

[0083] Example 5 The weak acid cation exchange resin 1 was replaced with the weak acid cation exchange resin 5. The weak acid cation exchange resin 5 was directly circulated with a ferric nitrate solution (0.45 mol / L, adjusted to pH 1.8±0.1 with nitric acid) through the resin bed at a flow rate of 3.0 BV / h. The subsequent operations were the same as in Example 1 except that the pretreatment step was omitted.

[0084] The concentrations of the components in the stripping solution are shown in Table 3. The contents of Fe and P are 22111.6 mg / L and 8183.5 mg / L, respectively. The Ca content is 15.3 mg / L, and the iron-calcium ratio is 1445. It can be used to prepare battery-grade iron phosphate (Ca 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron phosphate for batteries").

[0085] Example 6 The weak acid cation exchange resin 1 was replaced by the weak acid cation exchange resin 6, and the other conditions were the same as those in Example 1.

[0086] The concentrations of the components in the stripping solution are shown in Table 3. The contents of Fe and P are 19622.7 mg / L and 7095.2 mg / L, respectively. The Ca content is 14.2 mg / L, and the iron-calcium ratio is 1382. It can be used to prepare battery-grade iron phosphate (Ca 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron phosphate for batteries").

[0087] Example 7 The pH value of the phosphogypsum leachate was adjusted to 0.8 using a sulfuric acid solution, and the other conditions were the same as those in Example 2.

[0088] The concentrations of the components in the stripping solution are shown in Table 3. The contents of Fe and P are 22941.9 mg / L and 8502.4 mg / L, respectively. The Ca content is 13.3 mg / L, and the iron-calcium ratio is 1725. It can be used to prepare battery-grade iron phosphate (Ca 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron phosphate for batteries").

[0089] Example 8 Sodium hydroxide solution was used to adjust the pH value of the phosphogypsum leachate to 2.5, weak acid cation exchange resin 1 was replaced by weak acid cation exchange resin 5, and the other conditions were the same as those in Example 3.

[0090] The concentrations of the components in the stripping solution are shown in Table 3. The contents of Fe and P are 22198.2 mg / L and 8199.6 mg / L, respectively. The Ca content is 23.9 mg / L, and the iron-calcium ratio is 929. It can be used to prepare battery-grade iron phosphate (Ca 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron phosphate for batteries").

[0091] Example 9 The pH value of the phosphogypsum leachate was adjusted to 3.0 using sodium hydroxide solution, and the loaded resin was washed with H2SO4 at a pH of 1.5. The other conditions were the same as those in Example 3.

[0092] The concentrations of the components in the stripping solution are shown in Table 3. The contents of Fe and P are 21273.2 mg / L and 7801.5 mg / L, respectively. The Ca content is 17.9 mg / L, and the iron-calcium ratio is 1188. It can be used to prepare battery-grade iron phosphate (Ca 2+ ≤50 mg / L, meeting the Type II standard of "HG / T 4701-2021 Iron phosphate for batteries").

[0093] Comparative Example 1 The weak acid cation exchange resin 1 is replaced by a resin having the structural formula wherein M is a polystyrene resin, and the other conditions are the same as those in Example 1.

[0094] The concentrations of the components in the obtained stripping solution are shown in Table 3, wherein the contents of Fe and P are 23196.9 mg / L and 8753.4 mg / L, respectively, the Ca content is 87.8 mg / L, and the iron-to-calcium ratio is 264, which is 92.8% lower than that of the phosphorus adsorption resin in Example 1.

[0095] Table 3 Concentration of each component in the stripping solution (mg / L) Note: The data are the average of 3 parallel experiments, and the relative standard deviation (RSD) is less than 5%.

[0096] As shown in Table 3, weak acid cation exchange resin 4 performs best, with Ca 2+ Only 3.04 mg / L, which is 96.5% lower than that of comparative example 1 (87.8 mg / L), and the iron-calcium ratio (6824) is 24.8 times higher than that of comparative example 1 (264).

[0097] Example 10 (1) Adsorption experiment: 1 g of phosphorus adsorption resin 1-6 (prepared from weak acid cation exchange resins 1-6, respectively, according to Example 1) was added to 25 mL of phosphogypsum leachate (composition shown in Table 1, pH 1.7). The mixture was shaken at 25 ± 0.5 °C for 12 h, followed by solid-liquid separation at 150 rpm. The P concentration in the raffinate was determined by ICP-OES, and the removal rate was calculated (Table 4).

[0098] (2) Cyclic stability test: The phosphorus-loaded resin was washed with 75 mL of deionized water, stripped three times with 2.0 mol / L H₂SO₄ (25 mL each time), washed to neutrality, and reused 10 times. The phosphorus removal rate decay after the 10th cycle was measured.

[0099] (3) Dissolution test: Take 1 g of resin after 10 cycles, add 20 mL of H2SO4 solution with a pH of 1.5 or 0.8, and shake at 25±0.5℃ and 150 rpm for 30 min. After filtration, Fe 3+ concentration (Table 5), the method detection limit was 0.02 mg / L.

[0100] Comparative Example 2 The ferric sulfate was replaced with an equal volume of deionized water, and weak acid cation exchange resin 3 was used as the unmodified resin 3. The performance test was carried out with reference to Example 10. Unlike Example 10, the phosphorus adsorption resin was replaced with the unmodified resin 3. The P removal rates were shown in Table 4. Comparative Example 3 After pretreatment with reference to Example 1, weak-acid cation exchange resin 3 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 completion of the reaction, the resin bed was washed with deionized water at a flow rate of 2.0 BV / h, with a wash volume of 5 BV, to obtain an aluminum-modified resin. Performance testing was then conducted with reference to Example 10. Unlike Example 10, the phosphorus-adsorbing resin was replaced with the aluminum-modified resin. The resulting phosphorus removal rates are shown in Table 4.

[0101] Comparative Example 4 After pretreatment with reference to Example 1, weak acid cation exchange resin 3 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 completion of the reaction, the resin bed was washed with deionized water at a flow rate of 2.0 BV / h, with a wash volume of 5 BV, to obtain a lanthanum-modified resin. Performance testing was then conducted with reference to Example 10. Unlike Example 10, the phosphorus adsorption resin was replaced with the lanthanum-modified resin. The resulting phosphorus removal rates are shown in Table 4.

[0102] Table 4 Extraction of each element by each resin Table 5 Metal ion dissolution test results As shown in Table 4, the phosphorus removal rate of the phosphorus adsorption resin of the present invention is ≥95.0% (the aluminum / lanthanum modified resin is only 37.8% or 81.3%), and the Ca 2+ Total adsorption ≤ 20% (aluminum / lanthanum modified resin up to 9.8% or 12.6%), SO4 2- Adsorption rate ≤ 5% (5.8% or 6.8% for aluminum / lanthanum modified resin). 2+ The selectivity coefficient reached 987 (Comparative Examples 2-4 were all <50).

[0103] After 10 cycles, the phosphorus removal efficiency of phosphorus adsorption resin 3 decreased from 96.0% to 90.4% (absolute attenuation of 5.6 percentage points, capacity retention of 94.2%); while that of the lanthanum-modified resin decreased from 81.3% to 54.5% (attenuation of 26.8 percentage points, capacity retention of 67.0%). The single-cycle attenuation rate of phosphorus adsorption resin 3 (0.56%) was only 1 / 4.8 of that of the lanthanum-modified resin (2.68%).

[0104] As shown in Table 5, in a simulated acidic environment with a pH of 1.5, the Fe 3+The dissolution amount (0.09-0.17 mg / L) was reduced by 96.8%-98.7% compared with aluminum / lanthanum modified resin.

[0105] Under more stringent conditions of pH 0.8, the Fe 3+ The dissolution amount was still less than 0.2 mg / L, further verifying its structural stability under extremely acidic conditions.

[0106] The above merely describes exemplary embodiments or examples of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of this application.

Claims

1. 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 3+ The pH value of the phosphorus-containing wastewater is 0.8-3.0, the phosphorus concentration is 0.1-5 g / L, and the wastewater also contains Ca 0.1-1 g / L; the preparation method of the phosphorus adsorption resin comprises the following steps: i) contacting a weak acid cation exchange resin 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 completed, solid-liquid separation is performed to obtain loaded Fe 3+ Phosphorus adsorption resin.

2. The use according to claim 1, characterized in that The weak acid cation exchange resin comprises a resin of formula (I) and / or formula (II): (AND) (II) in: M is the base resin, R1 is -CH(COR5)2 or -(CH2) q COR6, R2 is hydrogen, -CH(COR5)2, -(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, n is an integer of 2-9, R3 is -CH2P(O)(OH)(Ph), -CH2P(O)(OH)2 or -(CH2) y P(O)(R7)2, R4 is hydrogen, -CH2P(O)(OH)(Ph), -(CH2) y P(O)(R7)2 or -(CH2) t SO3H, R5 is selected from hydroxy, optionally halogenated C 1- C 10 Alkoxy, optionally C1-C 10 an alkyl or halogen-substituted amino group, R6 is selected from hydroxy, optionally halogenated C 1- C 10 Alkoxy, optionally C1-C 10 an alkyl or halogen-substituted amino group, R7 is selected from phenyl or optionally halogenated C 1- C 10 Alkoxy, y, t and q are any integers from 1 to 9, Ph is phenyl, and halogen is Cl or Br.

3. The use according to claim 2, characterized in that M is selected from polystyrene resin, copolymer of styrene and divinylbenzene, phenolic resin, polyacrylic resin and silicon-based resin. Preferably, M is selected from polystyrene resin and 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 any one of claims 1 to 4, characterized in that R1 is selected from the following groups: 、 、 、 、 、 or , R2 is selected from hydrogen and the following groups: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 or , R3 is selected from the following groups: 、 、 、 、 、 、 、 、 or , R4 is selected from hydrogen and the following groups: 、 、 、 、 、 、 、 、 、 or ,in is the connection site between the group and A or N, Preferably, the resin of formula (I) and / or formula (II) has a structure selected from the following: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 or .

6. 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.

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

8. A method for selectively adsorbing phosphorus from phosphorus-containing wastewater, characterized in that: The following steps are involved: (a) contacting the phosphorus adsorption resin according to any one of claims 1 to 7 with phosphorus-containing wastewater for extraction, and recovering the phosphorus-loaded phosphorus adsorption resin by solid-liquid separation after the extraction is completed; (b) washing and stripping the phosphorus-loaded phosphorus adsorption resin with a detergent and a stripping agent in sequence to obtain a phosphorus-enriched stripping solution and a stripped phosphorus adsorption resin.

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

10. The method according to claim 8 or 9, characterized in that The detergent is deionized water or an acid 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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