High-sulfate reverse osmosis scale inhibitor applicable to treatment of iron phosphate production wastewater and preparation method of high-sulfate reverse osmosis scale inhibitor

Abstract

The invention discloses a high-sulfate reverse osmosis scale inhibitor suitable for iron phosphate production wastewater treatment, a reverse osmosis scale inhibitor under a high-sulfate working condition and a preparation method of the reverse osmosis scale inhibitor. The reverse osmosis scale inhibitor is prepared from the following raw materials in percentage by weight: 10 to 20 percent of bipolymer, 10 to 20 percent of 2-phosphonobutane-1, 2, 4-tricarboxylic acid, 8 to 10 percent of ethylene diamine tetra (methylene phosphonic acid) sodium, 6 to 10 percent of amino trimethylene phosphonic acid and the balance of ultrapure water, wherein the total mass of the bipolymer, the 2-phosphonobutane-1, 2, 4-tricarboxylic acid, the ethylene diamine tetra (methylene phosphonic acid) sodium and the amino trimethylene phosphonic acid are 100 percent. According to the invention, maleic anhydride and sulfonate free radical polymerization are utilized to prepare a novel binary copolymer aiming at a high-sulfate inflow water quality system; the reverse osmosis scale inhibitor disclosed by the invention can effectively inhibit the formation of calcium sulfate scale on the concentrated water side of a reverse osmosis membrane under low addition concentration, and particularly has a good calcium sulfate scale inhibition effect under the condition that the sulfate radical content is as high as 50g / L in an iron phosphate production wastewater membrane concentration system; meanwhile, all the raw materials are harmless to the environment and degradable, and the reverse osmosis agent belongs to an environment-friendly reverse osmosis agent.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial water treatment, and specifically relates to a reverse osmosis scale inhibitor suitable for high sulfate working conditions and a preparation method thereof, in particular to a reverse osmosis scale inhibitor dispersant for calcium sulfate in a ferric phosphate production wastewater membrane concentration system. Background Art

[0002] Reverse osmosis technology is a membrane separation and filtration technology with extremely small membrane pore size. Under a certain pressure drive, it can effectively remove impurities such as organic matter, colloids, heavy metal ions, bacteria and viruses in raw water to achieve the purpose of water purification. The separation process is efficient, environmentally friendly and has a wide range of applications.

[0003] In recent years, with the rapid development of the electric vehicle industry, the market demand for lithium iron phosphate cathode materials has become increasingly larger, and the demand for iron phosphate raw materials as precursors has also increased. The ammonia-based iron phosphate production process, which uses ferrous sulfate as a raw material to synthesize iron phosphate, has become the mainstream production process for iron phosphate due to its high product purity and stable performance. However, its production process will produce a large amount of high-salt wastewater through synthesis, water washing and other production processes. In order to achieve zero discharge and recycling of wastewater, multi-stage reverse osmosis membrane separation and concentration technology is widely used in the treatment of such wastewater. The mother liquor and wash water generated in the production process of ferric phosphate are high-salt inorganic wastewater containing different concentrations of metal ions such as iron, manganese, calcium, magnesium, ammonium ions, sulfate ions, and phosphate ions. The sulfate content is as high as 50 g / L (see the table below for details). As the wastewater undergoes multiple concentration and separation processes in a multi-stage membrane concentration system, the sulfate content on the concentrated water side becomes higher and higher, and the scaling tendency of calcium sulfate becomes easier to form. The surface of the reverse osmosis membrane is also easily contaminated by inorganic salt scale, causing the system water production rate to gradually decrease, which has a huge impact on the entire production process.

[0004] Table 1 Water quality characteristics of ferric phosphate production wastewater entering the membrane concentration system

[0005] Chinese patents with publication numbers CN114772755A and CN107758882A respectively disclose a high sulfate resistant reverse osmosis scale inhibitor and a preparation method, which can meet the scale inhibition requirements of high sulfate water quality, but the calcium ion and sulfate concentrations can only reach 18 g / L and 11.5 g / L respectively.

[0006] At present, there are relatively few reverse osmosis scale inhibitors specially developed for the characteristics of ferric phosphate production wastewater. As for the characteristics of ferric phosphate production wastewater, the sulfate, phosphate, ammonium, calcium ion and salt content are all very high. The existing sulfate reverse osmosis scale inhibitor is only suitable for ordinary water quality and does not meet the performance requirements of high-salt water quality. Summary of the invention

[0007] In view of the problems existing in the above-mentioned prior art, the present invention provides a reverse osmosis scale inhibitor suitable for high sulfate working conditions and a preparation method thereof, in particular, a reverse osmosis scale inhibitor dispersant for calcium sulfate in the ferric phosphate production wastewater membrane concentration system. When treating ferric phosphate wastewater with a sulfate content of more than 50 g / L, it has an excellent sulfate scale inhibition effect and effectively avoids scaling in the multi-stage reverse osmosis system.

[0008] To achieve the above object, the present invention provides the following technical solutions: A reverse osmosis antiscalant suitable for high sulfate conditions, comprising raw materials in the following proportions: The reverse osmosis scale inhibitor comprises raw materials in the following proportions: 10-20 parts of binary copolymer, 10-20 parts of 2-phosphonobutane-1,2,4-tricarboxylic acid, 10-30 parts of sodium ethylenediaminetetramethylenephosphonate, 5-18 parts of aminotrimethylenephosphonic acid, 0.1-1 parts of 4,4',4"-phosphoryltribenzoic acid and 10-30 parts of ultrapure water.

[0009] In some preferred embodiments, the reverse osmosis scale inhibitor comprises raw materials in the following proportions: 18 parts of binary copolymer, 18 parts of 2-phosphonobutane-1,2,4-tricarboxylic acid, 15 parts of sodium ethylenediaminetetramethylenephosphonate, 10 parts of aminotrimethylenephosphonic acid, 0.5 parts of 4,4′,4″-phosphoryltribenzoic acid, and 13 parts of ultrapure water.

[0010] The binary copolymer is prepared by free radical polymerization of maleic anhydride and sulfonate.

[0011] The sulfonate is selected from one or more of sodium allyl sulfonate, sodium allyloxyhydroxypropyl sulfonate, sodium methacrylate sulfonate, sodium α-olefin sulfonate and sodium lignin sulfonate.

[0012] The preparation method of the binary copolymer is as follows: S1: Maleic anhydride and water are mixed and stirred to dissolve; S2: dissolving sodium ethylenediaminetetraacetate in an aqueous solution and adding dropwise to S1, stirring and controlling the pH value of the reaction solution to 4.0-4.5; S3: After the addition is complete, add the sulfonate, introduce nitrogen, and heat to 60-100°C while stirring. S4: After the reaction is completed, add ammonium persulfate solution dropwise, and keep the temperature at 75-85°C for reaction after the addition is completed; S5: After the reaction is completed, the temperature is cooled to room temperature and then filtered and discharged to obtain a binary copolymer.

[0013] The mass ratio of maleic anhydride, sodium ethylenediaminetetraacetate, sulfonate and ammonium persulfate is 1:0.1-0.5:1-2:0.1-0.4.

[0014] The method for preparing the reverse osmosis scale inhibitor suitable for high sulfate conditions comprises the following steps: S1: Add sodium ethylenediaminetetramethylenephosphonate and aminotrimethylenephosphonic acid into water in sequence and mix until the mixture is uniform; S3: Add 2-phosphonobutane-1,2,4-tricarboxylic acid and the binary copolymer to S1, stir the reaction for 1-2 h, then add 4,4′,4″-phosphoryltribenzoic acid, stir at 50-80°C for 10-30 min, filter and discharge, and obtain a reverse osmosis scale inhibitor suitable for high sulfate conditions.

[0015] The invention uses maleic anhydride and sulfonate free radical polymerization to prepare a novel binary copolymer for a high sulfate influent water quality system; 4,4',4"-phosphoryltribenzoic acid is further added to the reverse osmosis scale inhibitor of the invention, which can effectively inhibit the formation of calcium sulfate scale on the concentrated water side of the reverse osmosis membrane at a low addition concentration, especially has a good calcium sulfate scale inhibition effect in the iron phosphate production wastewater membrane concentration system; at the same time, the raw materials of each component are harmless to the environment and are degradable, and belong to an environmentally friendly reverse osmosis agent. DETAILED DESCRIPTION

[0016] The present invention is further described below with reference to embodiments, but the scope of protection claimed by the present invention is not limited to the scope described in the embodiments.

[0017] The serious properties of the wastewater from the iron phosphate production in this case are shown in Table 2 Water quality characteristics of mother liquor and wash water produced in the production process of ferric phosphate

[0018] Example 1 The preparation method of the binary copolymer is as follows: S1: Add 8 kg of maleic anhydride and 65 kg of ultrapure water into a reaction stirred tank and stir to dissolve; S2: Dissolve 1 kg of sodium ethylenediaminetetraacetate in 4 kg of ultrapure water, transport to the high-level tank 1, and slowly drip into the reaction stirring tank, and control the pH value of the solution in the reaction stirring tank to be 4.0-4.5; S3: Add 10 kg of sodium allyl sulfonate into the reaction stirring kettle and stir to dissolve; S4: slowly introduce steam into the interlayer of the reaction stirring kettle, raise the temperature to 80°C and keep it stable, and simultaneously introduce nitrogen into the kettle from the bottom of the reaction stirring kettle; S5: Dissolve 2 kg of ammonium persulfate in 18 kg of ultrapure water, transfer to the high-level tank 2, and slowly drip into the reaction stirring tank for 1 hour; S6: After the addition is completed, the temperature is maintained at 75-85°C and stirred for 3 h; S7: After the heat preservation process is completed, the temperature is lowered to room temperature and then filtered and discharged to obtain a binary copolymer.

[0019] Example 2 The preparation method of reverse osmosis scale inhibitor suitable for high sulfate conditions is as follows: S1: 13 kg of ultrapure water is delivered to the reaction stirring tank; S2: 15 kg of sodium ethylenediaminetetramethylenephosphonate and 10 kg of aminotrimethylenephosphonic acid are added to the reaction stirring tank in sequence and mixed evenly; S3: 18 kg of 2-phosphonobutane-1,2,4-tricarboxylic acid and 18 kg of the binary copolymer prepared in Example 1 are sequentially added to a reaction stirring kettle, the reaction is stirred for 1 hour, and then 0.5 parts of 4,4′,4″-phosphoryltribenzoic acid are added, and the mixture is stirred at 70-80°C for 15 minutes. The material is filtered and discharged to obtain a reverse osmosis scale inhibitor suitable for high sulfate working conditions.

[0020] Example 3 The preparation method of reverse osmosis scale inhibitor suitable for high sulfate conditions is as follows: S1: 13 kg of ultrapure water is delivered to the reaction stirring tank; S2: 8 kg of sodium ethylenediaminetetramethylenephosphonate and 18 kg of aminotrimethylenephosphonic acid are added to the reaction stirring tank in sequence and mixed evenly; S3: 20 kg of 2-phosphonobutane-1,2,4-tricarboxylic acid and 11 kg of the binary copolymer prepared in Example 1 are sequentially added to a reaction stirring kettle, the reaction is stirred for 1 hour, and then 0.1 parts of 4,4′,4″-phosphoryltribenzoic acid are added, and the mixture is stirred at 70-80° C. for 15 minutes. The material is filtered and discharged to obtain a reverse osmosis scale inhibitor suitable for high sulfate working conditions.

[0021] Comparative Example 1 The preparation method of the reverse osmosis scale inhibitor and dispersant is consistent with the preparation method of Example 2, except that the binary copolymer prepared in Example 1 is not added.

[0022] Comparative Example 2 The preparation method of the reverse osmosis scale inhibitor and dispersant is consistent with the preparation method of Example 2, except that the 4,4′,4″-phosphoryltribenzoic acid prepared in Example 1 is not added.

[0023] The reverse osmosis scale inhibitor dispersant suitable for high sulfate working conditions prepared in the embodiment of the present invention was compared with the comparative example, and the calcium sulfate scale inhibition experiment was carried out according to Q / SY17126-2019 "Technical Requirements for Corrosion and Scale Inhibitors for Oilfield Water Treatment"; the scale inhibition test was carried out on the wash water and the mother liquor respectively, the sulfate ion concentration was 50000 ppm, the ammonium ion concentration was 10000 ppm, the phosphate ion concentration was 900 ppm, the calcium ion concentration was 1000 ppm, and the agent concentration was 15 ppm. The experimental results are shown in Table 1:

[0024] .

Claims

1. A high sulfate reverse osmosis scale inhibitor suitable for treating wastewater from iron phosphate production, characterized in that: The reverse osmosis scale inhibitor comprises raw materials in the following proportions: 10-20 parts of binary copolymer, 10-20 parts of 2-phosphonobutane-1,2,4-tricarboxylic acid, 10-30 parts of sodium ethylenediaminetetramethylenephosphonate, 5-18 parts of aminotrimethylenephosphonic acid, 0.1-1 parts of 4,4',4"-phosphoryltribenzoic acid and 10-30 parts of ultrapure water.

2. The high sulfate reverse osmosis scale inhibitor suitable for treating wastewater from iron phosphate production according to claim 1, characterized in that: The reverse osmosis scale inhibitor comprises raw materials in the following proportions: 18 parts of binary copolymer, 18 parts of 2-phosphonobutane-1,2,4-tricarboxylic acid, 15 parts of sodium ethylenediaminetetramethylenephosphonate, 10 parts of aminotrimethylenephosphonic acid, 0.5 parts of 4,4',4"-phosphoryltribenzoic acid and 13 parts of ultrapure water.

3. The high sulfate reverse osmosis scale inhibitor suitable for treating wastewater from iron phosphate production according to claim 1 or 2, characterized in that: The binary copolymer is prepared by free radical polymerization of maleic anhydride and sulfonate.

4. The high sulfate reverse osmosis scale inhibitor suitable for treating wastewater from iron phosphate production according to claim 3, characterized in that: The sulfonate is selected from one or more of sodium allyl sulfonate, sodium allyloxyhydroxypropyl sulfonate, sodium methacrylate sulfonate, sodium α-olefin sulfonate, and sodium lignin sulfonate.

5. The high sulfate reverse osmosis scale inhibitor suitable for treating wastewater from iron phosphate production according to claim 4, characterized in that: The preparation method of the binary copolymer is as follows: S1: Maleic anhydride and water are mixed and stirred to dissolve; S2: dissolving sodium ethylenediaminetetraacetate in an aqueous solution and adding dropwise to S1, stirring and controlling the pH value of the reaction solution to 4.0-4.5; S3: After the addition is complete, add the sulfonate, introduce nitrogen, and heat to 60-100°C while stirring. S4: After the reaction is completed, add ammonium persulfate solution dropwise, and keep the temperature at 75-85°C for reaction after the addition is completed; S5: After the reaction is completed, the temperature is cooled to room temperature and then filtered and discharged to obtain a binary copolymer.

6. The high sulfate reverse osmosis scale inhibitor suitable for treating wastewater from iron phosphate production according to claim 5, characterized in that: The mass ratio of maleic anhydride, sodium ethylenediaminetetraacetate, sulfonate and ammonium persulfate is 1:0.1-0.5:1-2:0.1-0.

4.

7. The method for preparing a high sulfate reverse osmosis scale inhibitor suitable for treating wastewater from iron phosphate production according to any one of claims 1 to 6, characterized in that: The following steps are included: S1: Add sodium ethylenediaminetetramethylenephosphonate and aminotrimethylenephosphonic acid into ultrapure water in sequence and mix until the mixture is uniform; S3: Add 2-phosphonobutane-1,2,4-tricarboxylic acid and the binary copolymer to S1, stir the reaction for 1-2 h, then add 4,4′,4″-phosphoryltribenzoic acid, stir at 50-80°C for 10-30 min, filter and discharge, and obtain a reverse osmosis scale inhibitor suitable for high sulfate conditions.

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