Polyamide acid-resistant nanofiltration membrane and its application in arsenic removal in hair dye preparation

Abstract

The application discloses a kind of polyamide acid-resistant nanofiltration membrane and its application in hair dye preparation of dearsenic.The acid-resistant nanofiltration membrane of amide is obtained by the interface reaction of polyamine monomer and trimesoyl chloride on the ultrafiltration support bottom membrane, and the polyamide acid-resistant nanofiltration membrane containing trog structure is obtained.The method for removing arsenic in hydroxyethylidene diphosphonic acid is at least once filtering treatment by using the polyamide acid-resistant nanofiltration membrane containing trog structure, and after secondary filtering treatment, the concentration of arsenate in hydroxyethylidene diphosphonic acid is reduced from 480.02 mg / kg to 4.60 mg / kg, and the arsenic content of hair dye prepared from the hydroxyethylidene diphosphonic acid is less than 0.07 mg / kg.The polyamide acid-resistant nanofiltration membrane containing trog structure obtained by using the limited preparation method has greatly improved acid resistance, higher separation selectivity, and can effectively remove arsenic in hydroxyethylidene diphosphonic acid, greatly reducing the arsenic content in hair dye.

Description

Technical Field

[0001] This invention discloses a polyamide acid-resistant nanofiltration membrane and its application in the preparation of hair dye for arsenic removal. The polyamide acid-resistant nanofiltration membrane contains a Trog structure and can be used to remove arsenic from hydroxyethyl diphosphate, a raw material for hair dye. The arsenic-removed hydroxyethyl diphosphate is then used as a raw material for hair dye, thereby achieving the preparation of a low-arsenic hair dye. Background Technology

[0002] As living standards improve, people are paying more and more attention to their appearance, and hair styling methods such as dyeing and perming are becoming increasingly popular. Consequently, the demand for hair dye is also increasing. However, the safety of hair dyes, particularly those containing excessive levels of heavy metals, has always been a major concern for consumers. Hair dyes often contain heavy metals such as mercury, lead, arsenic, and cadmium. These heavy metals can enter the bloodstream through tiny wounds on the scalp during the dyeing process, posing a serious threat to health if accumulated over time. Therefore, the national standard "Cosmetic Safety Technical Specifications" (2015 edition) sets strict limits on the levels of heavy metals such as mercury, lead, arsenic, and cadmium.

[0003] Arsenic and its compounds are widely present in nature, making hair dye raw materials and production processes highly susceptible to arsenic contamination. In May 2023, *Consumer Reports* tested the heavy metal levels in 14 top-selling hair dye products on the market. The results showed that cadmium was not detected in any of the 14 products; trace amounts of mercury were detected in 5 products; and a certain amount of lead was detected in two products. All of these test results met national standards. However, arsenic was detected in 7 products, with two products containing 6.99 mg / kg and 3.76 mg / kg of arsenic, respectively, exceeding the national standard limit and thus being substandard. Hydroxyethyl diphosphate is a commonly used component in hair dye formulations, primarily used as a chelating agent and stabilizer. On one hand, it can chelate with metal ions such as calcium and magnesium through its phosphonic acid groups to form complexes, thereby inhibiting the accelerated oxidation reaction or color change of the hair dye caused by metal ions, prolonging the duration of the dyeing effect. On the other hand, it can chelate metal ions (such as iron ions) required for bacterial metabolism, playing a role in preservation and maintaining the stability of the hair dye. Because phosphorus and arsenic have highly similar chemical properties and often coexist in nature, hydroxyethyl diphosphate often contains residual arsenic impurities, which is a major reason for excessive arsenic content in hair dyes. Therefore, effectively inhibiting the arsenic content in hydroxyethyl diphosphate directly affects whether the arsenic content of hair dye products meets the standards.

[0004] Currently, effective methods for removing heavy metals such as arsenic include flocculation, ion exchange, electrodialysis, and nanofiltration membrane technology. Chinese patent CN101108306A discloses a method for removing heavy metals such as cadmium and lead from plant extracts using electrodialysis, with significant reduction effects. Chinese patent CN 102145260B reports a copper-zinc-silver alloy metal nanofiltration membrane and its preparation method, which shows good effectiveness in removing harmful heavy metal ions such as lead, mercury, chromium, and arsenic from water. Arsenic usually exists in the form of arsenate in shampoo ingredients containing hydroxyethyl diphosphate, with a molecular weight of 138.92, while hydroxyethyl diphosphate has a molecular weight of 206.03, and can be separated by nanofiltration membranes. Conventional nanofiltration membranes can only be used in neutral environments, but hydroxyethyl diphosphate, as a polybasic acid, has an aqueous solution with a pH of 1-2, exhibiting strong acidity. Currently, commercially available nanofiltration membrane materials are mainly polyamides. However, polyamides are prone to hydrolysis in acidic environments, which leads to a significant decrease in performance and limits their application in acidic solutions. Therefore, developing acid-resistant nanofiltration membranes for acidic solution treatment and using them for the removal of heavy metals such as arsenic from hydroxyethyl diphosphate has great application value. Summary of the Invention

[0005] To address the problem of arsenic residues in existing hair dye raw material hydroxyethyl diphosphate and the resulting excessive arsenic content in the prepared hair dye, this invention aims to provide a polyamide acid-resistant nanofiltration membrane and its application in hair dye preparation for arsenic removal. Before hair dye preparation, the arsenic in the hair dye raw material hydroxyethyl diphosphate is removed by the polyamide acid-resistant nanofiltration membrane containing the Trog structure of this invention. The arsenic-removed hydroxyethyl diphosphate is then used to prepare the hair dye, thereby achieving the preparation of a low-arsenic hair dye.

[0006] This invention discloses a polyamide acid-resistant nanofiltration membrane, which is obtained by an interfacial reaction between a polyamine monomer and pyromellitic trimethylol chloride on an ultrafiltration support substrate to obtain a polyamide acid-resistant nanofiltration membrane with a Trog structure.

[0007] Furthermore, the present invention also specifies a method for preparing the polyamide acid-resistant nanofiltration membrane, specifically: an ultrafiltration support membrane is successively immersed in an aqueous solution containing a polyamine monomer and an organic solution containing trimesoyl chloride, and then heat-treated to obtain a polyamide acid-resistant nanofiltration membrane with a Trog structure, wherein the polyamine monomer includes any one of tetraaminoporphyrin, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine or 1,3,5-tris(4-aminophenyl)benzene.

[0008] Furthermore, the present invention further specifies that the aqueous solution also includes an acid absorbent and a surfactant, wherein the acid absorbent includes any one of sodium carbonate, potassium hydroxide, or sodium hydroxide, preferably potassium hydroxide or sodium hydroxide; and the surfactant includes at least one of sodium dodecyl sulfate, sodium dodecyl sulfonate, and sodium dodecylbenzene sulfonate.

[0009] Furthermore, the present invention also specifies that the organic solvent of the organic phase solution includes at least one selected from Isopar G, cyclohexane, n-hexane, n-heptane, and n-decane.

[0010] Furthermore, the present invention also specifies that the heating temperature used for heat treatment is 60~100℃ and the heating time is 5~15min.

[0011] Furthermore, the present invention also specifies that the ultrafiltration support membrane includes any one of polyacrylonitrile ultrafiltration membrane, polypropylene ultrafiltration membrane, polysulfone ultrafiltration membrane, polyethersulfone ultrafiltration membrane, and polyetheretherketone ultrafiltration membrane.

[0012] Furthermore, the present invention specifies a method for preparing a polyamide acid-resistant nanofiltration membrane, which specifically includes the following steps:

[0013] 1) Preparation of aqueous solution:

[0014] A polyamine monomer, acid absorbent, surfactant, and water are stirred evenly in a mass percentage ratio of (0.5%~1.2%) : (0.1%~1%) : (0.1~2.2%) : (95.6%~99.3%) to obtain an aqueous solution. The polyamine monomer includes any one of tetraaminoporphyrin, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 1,3,5-tris(4-aminophenyl)benzene.

[0015] 2) Preparation of organic phase solution:

[0016] Trimethylbenzene chloride and an organic solvent are stirred evenly according to the required amount to prepare an organic phase solution, wherein the mass percentage of trimethylbenzene chloride in the organic phase solution is 0.05%~0.2%;

[0017] 3) Preparation of acid-resistant polyamide nanofiltration membranes with Trog structure:

[0018] First, immerse the ultrafiltration support membrane in the aqueous solution prepared in step 1) and keep it for 35~280s. After removing the residual aqueous solution on the surface of the ultrafiltration support membrane, immerse it in the organic solution prepared in step 2) and keep it for 35~320s. After removing the residual organic solution on the surface of the ultrafiltration support membrane, heat treatment is performed to obtain a polyamide acid-resistant nanofiltration membrane with a Trog structure.

[0019] Furthermore, the present invention also defines a method for removing arsenic from hydroxyethyl diphosphate, wherein the hydroxyethyl diphosphate is filtered at least once using a polyamide acid-resistant nanofiltration membrane.

[0020] After filtration of hydroxyethyl diphosphate using the polyamide acid-resistant nanofiltration membrane prepared according to the present invention, the hydroxyethyl diphosphate rejection rate is above 95%, and the arsenate rejection rate in hydroxyethyl diphosphate is below 10%. After one filtration treatment, the arsenate concentration in hydroxyethyl diphosphate decreases from 480.02 mg / kg to below 47.0 mg / kg, and after a second filtration treatment, the arsenate concentration in hydroxyethyl diphosphate decreases to below 4.60 mg / kg.

[0021] Furthermore, this invention also specifies the application of arsenic-removed hydroxyethylene diphosphate in the preparation of hair dyes. The specific application process is as follows: the dyeing agent and oxidizing agent of the hair dye are prepared according to conventional ratios. The oxidizing agent is then mixed with arsenic-removed hydroxyethylene diphosphate using a polyamide acid-resistant nanofiltration membrane with a Trog structure. The dyeing agent and oxidizing agent are mixed in a 1:1 mass ratio to obtain the hair dye. Test results show that using hydroxyethylene diphosphate treated by this invention to prepare hair dyes can significantly reduce the arsenic content in the product: the arsenic content of hair dyes prepared with hydroxyethylene diphosphate treated once is less than 0.07 mg / kg; the arsenic content of hair dyes prepared with hydroxyethylene diphosphate treated twice is lower than the detection concentration of 0.01 mg / kg, which greatly ensures consumer safety and also enhances the competitiveness of the product.

[0022] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0023] 1) By using limited raw materials and preparation methods, this invention enables polyamide polymer chains to form a tightly interwoven three-dimensional network structure with a highly regular structure, more uniform pore size, and narrower pore size distribution during the film formation process, which can more accurately separate hydroxyethyl phosphate and arsenic oxide according to molecular size.

[0024] 2) The polyamide acid-resistant nanofiltration membrane prepared by this invention has a positively charged surface under strong acid conditions, while the target pollutant may be negatively charged. Through electrostatic repulsion, the pollutant can be further prevented from passing through, significantly improving the membrane's separation selectivity for the hair dye component hydroxyethyl phosphate and its arsenic oxide, achieving highly selective separation. The inventors compared the retention rates of hydroxyethyl phosphate and arsenate of the polyamide acid-resistant nanofiltration membrane prepared by this invention with those of conventional piperazine amide nanofiltration membranes. The test results show that, compared with conventional piperazine amide nanofiltration membranes, the polyamide acid-resistant nanofiltration membrane prepared by this invention has excellent separation selectivity for the hair dye component hydroxyethyl phosphate and its arsenate, effectively removing arsenate from hydroxyethyl phosphate. After treatment, the hydroxyethyl phosphate retention rate is above 95%, and the arsenate retention rate in hydroxyethyl phosphate is below 10%. After one filtration treatment, the arsenate concentration in hydroxyethyl phosphate decreased from 480.02 mg / kg to 47.0 mg / kg. After secondary filtration, the arsenate concentration in hydroxyethyl diphosphate decreased to below 4.60 mg / kg.

[0025] 3) The polyamide acid-resistant nanofiltration membrane with the Trog structure prepared by this invention has a higher degree of cross-linking between polymer chains and a more compact and stable structure. This overcomes the problem that conventional polyamide membranes are prone to hydrolysis and degradation in strong acids, which leads to performance failure. It endows the membrane with excellent acid resistance and can also expand its application in industrial waste acid recovery, with broad application prospects. Attached Figure Description

[0026] Figure 1 This is a SEM image of the acid-resistant nanofiltration membrane prepared in Example 1 of this invention;

[0027] Figure 2 This is a SEM image of the acid-resistant nanofiltration membrane prepared in Example 1 after being soaked in hydrochloric acid aqueous solution.

[0028] Figure 3 A schematic diagram of the Trog structure of the acid-resistant nanofiltration membrane prepared in Example 1 of this invention. Detailed Implementation

[0029] The technical solution of the present invention will be further described below with reference to the embodiments and the accompanying drawings, but the scope of protection of the present invention is not limited thereto.

[0030] Example 1: Preparation of acid-resistant polyamide nanofiltration membrane with Trog structure

[0031] 1) Preparation of aqueous solution:

[0032] Aqueous solution was prepared by mixing polyamine monomer tetraaminoporphyrin, acid absorbent sodium hydroxide, surfactant sodium dodecyl sulfate, and water in a mass percentage ratio of 1.0% : 0.5% : 0.1% : 98.4%.

[0033] 2) Preparation of organic phase solution

[0034] Trimethylbenzene chloride (TMC) and organic solvent Isopar G were stirred evenly in the required amounts to prepare an organic phase solution; the mass percentage of the TMC monomer in the organic phase solution was 0.15%.

[0035] 3) Preparation of acid-resistant polyamide nanofiltration membranes with Trog structure

[0036] The cleaned ultrafiltration support membrane (specifically a polyethersulfone ultrafiltration membrane with a molecular weight cutoff of 30 kDa) was immersed in the aqueous solution and held for 30 seconds. Then, the residual aqueous solution on the surface of the ultrafiltration support membrane was removed with a rubber roller, and then it was immersed in the organic solution and held for 120 seconds. After removing the residual organic solution on the surface of the ultrafiltration support membrane with a rubber roller, it was then heat-treated in an oven (heating temperature of 80°C and heating time of 10 min) to prepare a polyamide acid-resistant nanofiltration membrane with a Trog structure.

[0037] SEM images of the prepared acid-resistant nanofiltration membrane are shown below. Figure 1 As shown, from Figure 1 As can be seen, its surface is smooth and dense; the acid-resistant nanofiltration membrane was treated by immersion in hydrochloric acid aqueous solution, and the SEM image of the treated acid-resistant nanofiltration membrane is shown below. Figure 2 As shown, from Figure 2 As can be seen, its surface morphology has not changed much, indicating that it has good acid resistance. Figure 3 This is a schematic diagram of the Trog structure of the acid-resistant nanofiltration membrane prepared in Example 1.

[0038] Example 2: Preparation of acid-resistant polyamide nanofiltration membrane with Trog structure

[0039] 1) Preparation of aqueous solution:

[0040] Aqueous solution was prepared by mixing polyamine monomer 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, acid absorbent potassium hydroxide, surfactant sodium dodecyl sulfonate, and water in a mass percentage ratio of 1.2% : 1.0% : 2.2% : 95.6%.

[0041] 2) Preparation of organic phase solution

[0042] Trimethylbenzene chloride (TMC) and cyclohexane, an organic solvent, are stirred evenly in the required amounts to prepare an organic phase solution; the mass percentage of the TMC monomer in the organic phase solution is 0.05%.

[0043] 3) Preparation of acid-resistant polyamide nanofiltration membranes with Trog structure

[0044] The cleaned ultrafiltration support membrane (specifically a polyacrylonitrile ultrafiltration membrane with a molecular weight cutoff of 30 kDa) was immersed in the aqueous solution and held for 35 seconds. After removing the residual aqueous solution from the surface of the ultrafiltration support membrane with a rubber roller, it was then immersed in the organic solution and held for 320 seconds. After removing the residual organic solution from the surface of the ultrafiltration support membrane with a rubber roller, it was then heat-treated in an oven (heating temperature of 60°C and heating time of 15 min) to prepare a polyamide acid-resistant nanofiltration membrane with a Trog structure.

[0045] Example 3: Preparation of acid-resistant polyamide nanofiltration membrane with Trog structure

[0046] 1) Preparation of aqueous solution:

[0047] Aqueous solution was prepared by mixing polyamine monomer 1,3,5-tris(4-aminophenyl)benzene, acid absorbent sodium hydroxide, surfactant sodium dodecylbenzenesulfonate, and water in a mass percentage ratio of 0.8% : 0.1% : 1.2% : 97.9%.

[0048] 2) Preparation of organic phase solution

[0049] Trimethylbenzene chloride (TMC) and the organic solvent n-hexane were stirred evenly in the required amounts to prepare an organic phase solution; the mass percentage of the TMC monomer in the organic phase solution was 0.2%.

[0050] 3) Preparation of acid-resistant polyamide nanofiltration membranes with Trog structure

[0051] The cleaned ultrafiltration support membrane (specifically a polypropylene ultrafiltration membrane with a molecular weight cutoff of 30 kDa) was immersed in the aqueous solution and held for 280 s. After removing the residual aqueous solution from the surface of the ultrafiltration support membrane with a rubber roller, it was then immersed in the organic solution and held for 250 s. After removing the residual organic solution from the surface of the ultrafiltration support membrane with a rubber roller, it was then heat-treated in an oven (heating temperature of 100 °C and heating time of 5 min) to prepare a polyamide acid-resistant nanofiltration membrane with a Trog structure.

[0052] Example 4: Preparation of acid-resistant polyamide nanofiltration membrane with Trog structure

[0053] 1) Preparation of aqueous solution:

[0054] Aqueous solution was prepared by mixing polyamine monomer tetraaminoporphyrin, acid absorbent potassium hydroxide, surfactant sodium dodecyl sulfate, and water in a mass percentage ratio of 0.5% : 0.7% : 1.4% : 97.4%.

[0055] 2) Preparation of organic phase solution

[0056] Trimethylbenzene chloride (TMC) and the organic solvent n-heptane were stirred evenly in the required amounts to prepare an organic phase solution; the mass percentage of the TMC monomer in the organic phase solution was 0.12%.

[0057] 3) Preparation of acid-resistant polyamide nanofiltration membranes with Trog structure

[0058] The cleaned ultrafiltration support membrane (specifically a polysulfone ultrafiltration membrane with a molecular weight cutoff of 30 kDa) was immersed in the aqueous solution and held for 100 s. Then, the residual aqueous solution on the surface of the ultrafiltration support membrane was removed with a rubber roller, and then it was immersed in the organic solution and held for 35 s. After removing the residual organic solution on the surface of the ultrafiltration support membrane with a rubber roller, it was then heat-treated in an oven (heating temperature of 70 °C and heating time of 12 min) to prepare a polyamide acid-resistant nanofiltration membrane with a Trog structure.

[0059] Example 5: Preparation of acid-resistant polyamide nanofiltration membrane with Trog structure

[0060] 1) Preparation of aqueous solution:

[0061] Aqueous solution was prepared by mixing polyamine monomer 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, acid absorbent sodium hydroxide, surfactant sodium dodecyl sulfonate, and water in a mass percentage ratio of 0.5% : 0.1% : 0.1% : 99.3%.

[0062] 2) Preparation of organic phase solution

[0063] Trimethylbenzene chloride (TMC) and the organic solvent n-decane were stirred evenly in the required amounts to prepare an organic phase solution; the mass percentage of the TMC monomer in the organic phase solution was 0.18%.

[0064] 3) Preparation of acid-resistant polyamide nanofiltration membranes with Trog structure

[0065] The cleaned ultrafiltration support membrane (specifically polyetheretherketone with a molecular weight cutoff of 30 kDa) was immersed in the aqueous solution and held for 150 s. After removing the residual aqueous solution from the surface of the ultrafiltration support membrane with a rubber roller, it was then immersed in the organic solution and held for 110 s. After removing the residual organic solution from the surface of the ultrafiltration support membrane with a rubber roller, it was then heat-treated in an oven (heating temperature of 90 °C and heating time of 10 min) to prepare a polyamide acid-resistant nanofiltration membrane with a Trog structure.

[0066] Application Examples: Arsenic Removal from Hydroxyethyldiphosphate and Its Effect in Hair Dyes

[0067] This invention also provides the application of the polyamide acid-resistant nanofiltration membrane prepared according to the preparation methods of Examples 1-5 in the removal of arsenic from hydroxyethyl diphosphate, a raw material in hair dyes. According to GB / T 34242-2017, the prepared polyamide acid-resistant nanofiltration membrane was used for an arsenic removal test in the hair dye component hydroxyethyl diphosphate, with an operating pressure of 1.0 MPa. The tetraaminoporphyrin monomer in step “1) Preparation of Aqueous Solution” of Example 1 was replaced with piperazine, and other operations were the same as in Example 1, to prepare a polypiperazine amide nanofiltration membrane, which was used as Comparative Example 1 for comparative testing. The performance data are listed in Tables 1 and 2. Using the 2015 edition of the "Cosmetic Safety Technical Specifications" [Chapter 4 (1.4 Method 1)], the arsenic content of hydroxyethyl diphosphate after one and two filtrations using the polyamide acid-resistant nanofiltration membrane prepared in Examples 1-5, and hydroxyethyl diphosphate without arsenic removal treatment, were tested. Hydroxyethyl diphosphate without arsenic removal treatment was used as Comparative Example 2. The test results are shown in Table 3.

[0068] Table 1: Performance comparison of the polyamide acid-resistant nanofiltration membranes prepared in Examples 1-5 and the polypiperazine amide nanofiltration membrane of Comparative Example 1

[0069]

[0070] Table 2: Performance comparison of polyamide acid-resistant nanofiltration membrane and polypiperazine amide nanofiltration membrane of Comparative Example 1 after 7 days of operation.

[0071]

[0072] Table 3: Arsenic content (mg / kg) of hydroxyethyl diphosphate without arsenic removal treatment (Comparative Example 2) and after treatment with polyamide acid-resistant nanofiltration membranes prepared in Examples 1-5.

[0073]

[0074] The test results in Tables 1 and 2 show that, compared to Comparative Example 1 (a conventional polypiperazine amide nanofiltration membrane), the polyamide acid-resistant nanofiltration membrane prepared in this invention exhibits excellent separation selectivity for the hair dye components hydroxyethyl phosphate and arsenate. The hydroxyethyl phosphate rejection rate is above 95%, while the arsenate rejection rate is below 10%. After 7 days of operation, its rejection rates for both hydroxyethyl phosphate and arsenate remain essentially unchanged, while the rejection rate for hydroxyethyl phosphate in Comparative Example 1 decreased from the initial 87.6% to 47.6%, and the rejection rate for arsenate decreased significantly. The salt rejection rate decreased from the initial 34.15% to 23.15%, indicating that the polyamide acid-resistant nanofiltration membrane prepared in this invention has excellent acid resistance compared to conventional piperazine amide nanofiltration membranes. As shown in Tables 1 and 3, the prepared polyamide acid-resistant nanofiltration membrane has good removal performance for arsenate in hydroxyethyl diphosphate. Compared with hydroxyethyl diphosphate without arsenic removal treatment (Comparative Example 2), the removal rate after one treatment is above 90%, which can reduce the arsenate concentration from 480.02 mg / kg to below 47.0 mg / kg. After two treatments, it can be reduced to below 4.60 mg / kg.

[0075] Two-component hair dyes are currently the mainstream type of permanent hair dyes. They generally consist of a dyeing agent (referred to as Agent 1) and an oxidizing agent (referred to as Agent 2). During the dyeing process, Agent 1 and Agent 2 are mixed in a 1:1 mass ratio. Hydroxyethylene diphosphate is often used in the formulation of Agent 2 in hair dyes; therefore, this invention also specifies the application of hydroxyethylene diphosphate separated by a polyamide acid-resistant nanofiltration membrane in the preparation of Agent 2 in hair dyes.

[0076] The hydroxyethyl diphosphate obtained in Examples 1-3 of Table 3 above was used as component 2 of the hair dye, and corresponding hair dye 2 agents were prepared according to the formulations shown in Table 4 (see Examples 6-8). Meanwhile, hair dye 2 agents prepared from hydroxyethyl diphosphate without arsenic removal treatment according to the formulations shown in Examples 6-8 of Table 4 were used as comparative examples. Component 1 and Component 2 were mixed at a 1:1 mass ratio, and the arsenic content of the mixed hair dye products was tested according to Chapter 4 (1.4 Method 1) of the 2015 edition of the "Cosmetic Safety Technical Specifications". The test results are shown in Table 4:

[0077] Table 4. Components of several representative hair dyes and the arsenic content in the hair dyes they are prepared from.

[0078]

[0079] *Note:

[0080] 1) One filtration refers to the process of using the prepared polyamide acid-resistant nanofiltration membrane to filter once to obtain hydroxyethyl diphosphate to prepare hair dye agent 2, and then mixing it with agent 1 in a 1:1 mass ratio to obtain the hair dye product.

[0081] 2) Filtration twice refers to the process of using the prepared polyamide acid-resistant nanofiltration membrane to filter once and then washing and filtering once to prepare hair dye agent 2 with hydroxyethyl diphosphate, and then mixing it with agent 1 in a 1:1 mass ratio to obtain the hair dye product.

[0082] 3) The comparative ratio refers to the hair dye product obtained by preparing hair dye agent 2 with hydroxyethyl diphosphate that has not been dearsenic treated, and then mixing it with agent 1 in a 1:1 mass ratio.

[0083] As shown in Table 4, compared with the hair dye prepared from untreated hydroxyethyl diphosphate (comparative example), the hair dye prepared from hydroxyethyl diphosphate treated with the polyamide acid-resistant nanofiltration membrane of this invention can significantly reduce the arsenic content in the product: the arsenic content of the hair dye prepared from hydroxyethyl diphosphate after one treatment is less than 0.07 mg / kg, which is not only far below the national standard of 2.0 mg / kg, but also below the limit for arsenic set by the German Federal Office for Consumer Protection and Food Safety (BVL) (0.5 mg / kg); the arsenic content of the hair dye prepared from hydroxyethyl diphosphate after two treatments is lower than the detected concentration of 0.01 mg / kg, which greatly ensures consumer safety and also enhances the competitiveness of the product.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations.

Claims

1. A method for removing arsenic from hydroxyethyl diphosphate, characterized in that... Hydroxyethyl diphosphate was filtered at least once using a polyamide acid-resistant nanofiltration membrane, wherein the polyamide acid-resistant nanofiltration membrane was obtained by an interfacial reaction between a polyamine monomer and trimesoyl chloride on an ultrafiltration support substrate membrane and a polyamide acid-resistant nanofiltration membrane containing a Trog structure. The method for preparing the polyamide acid-resistant nanofiltration membrane is as follows: an ultrafiltration support membrane is successively immersed in an aqueous solution containing polyamine monomers and an organic solution containing trimesoyl chloride, and then heat-treated to obtain a polyamide acid-resistant nanofiltration membrane with a Trog structure. The polyamine monomers include any one of tetraaminoporphyrin, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, or 1,3,5-tris(4-aminophenyl)benzene.

2. The method for removing arsenic from hydroxyethyl diphosphate according to claim 1, characterized in that... The aqueous solution also includes an acid absorbent and a surfactant. The acid absorbent includes any one of sodium carbonate, potassium hydroxide, or sodium hydroxide. The surfactant includes at least one of sodium dodecyl sulfate, sodium dodecyl sulfonate, and sodium dodecylbenzene sulfonate.

3. The method for removing arsenic from hydroxyethyl diphosphate according to claim 1, characterized in that... The organic solvent of the organic phase solution includes at least one of Isopar G, cyclohexane, n-hexane, n-heptane, and n-decane.

4. The method for removing arsenic from hydroxyethyl diphosphate according to claim 1, characterized in that... The heat treatment uses a heating temperature of 60~100℃ and a heating time of 5~15min.

5. The method for removing arsenic from hydroxyethyl diphosphate according to any one of claims 1-4, characterized in that... The ultrafiltration support membrane includes any one of polyacrylonitrile ultrafiltration membrane, polypropylene ultrafiltration membrane, polysulfone ultrafiltration membrane, polyethersulfone ultrafiltration membrane, and polyetheretherketone ultrafiltration membrane.

6. The method for removing arsenic from hydroxyethyl diphosphate according to claim 1, characterized in that... Includes the following steps: 1) Preparation of aqueous solution: A polyamine monomer, acid absorbent, surfactant, and water are stirred evenly in a mass percentage ratio of 0.5%~1.2%:0.1%~1%:0.1~2.2%:95.6%~99.3% to obtain an aqueous solution. The polyamine monomer includes any one of tetraaminoporphyrin, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 1,3,5-tris(4-aminophenyl)benzene. 2) Preparation of organic phase solution: Trimethylbenzene chloride and an organic solvent are stirred evenly according to the required amount to prepare an organic phase solution, wherein the mass percentage of trimethylbenzene chloride in the organic phase solution is 0.05%~0.2%; 3) Preparation of acid-resistant polyamide nanofiltration membranes with Trog structure: First, immerse the ultrafiltration support membrane in the aqueous solution prepared in step 1) and keep it for 35~280s. After removing the residual aqueous solution on the surface of the ultrafiltration support membrane, immerse it in the organic solution prepared in step 2) and keep it for 35~320s. After removing the residual organic solution on the surface of the ultrafiltration support membrane, heat treatment is performed to obtain a polyamide acid-resistant nanofiltration membrane with a Trog structure.

7. The method for removing arsenic from hydroxyethyl diphosphate according to claim 1, characterized in that... After treatment with a polyamide acid-resistant nanofiltration membrane, the hydroxyethyl diphosphate (HEDP) rejection rate is over 95%, and the arsenate rejection rate in HEDP is below 10%. After one filtration treatment, the arsenate concentration in HEDP decreases from 480.02 mg / kg to below 47.0 mg / kg, and after a second filtration treatment, the arsenate concentration in HEDP decreases to below 4.60 mg / kg.

8. The application of hydroxyethyl diphosphate obtained by the removal method according to claim 1 in the preparation of hair dye.

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