Method for regulating solubility of disodium monotetradecyl phosphate by pH (Potential of Hydrogen)
Through the pH regulation method, the reversible conversion between disodium monotetradecyl phosphate and monotetradecyl phosphate is achieved, solving the problem of low recovery efficiency of phosphate-type surfactant, achieving efficient recycling and reuse, and maintaining its excellent performance.
Patent Information
- Application Number
- CN202411650532.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-19
- Publication Date
- 2025-03-11
AI Technical Summary
The prior art is difficult to efficiently recover and reuse phosphate surfactants, especially in the context of the eutrophication problem of water bodies, the recovery efficiency of phosphate surfactants is relatively low.
Through the pH-regulating method, the reversible conversion between disodium monotetradecyl phosphate and monotetradecyl phosphate is achieved by reversible change in pH, changing its solubility, thereby realizing its recovery and reuse in micelle aqueous solutions, emulsions and high internal phase emulsions.
The efficient recycling and reuse of disodium monotetradecyl phosphate is achieved, with a recovery rate of no less than 98%, and the excellent performance of forming a high internal phase emulsion is maintained, solving the problem of low recovery efficiency of phosphate-type surfactant.
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Figure CN119591634A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to regulating the solubility of anionic surfactants by using pH, in particular to regulating the solubility of disodium tetradecyl phosphate monoester salt, and belongs to the technical field of sustainable fine organic chemicals. Background Art
[0002] In recent years, the switch control of surfactants has attracted widespread attention from chemists, which has led to various types of switch surfactants becoming a hot spot for the sustainable development of surfactant science and industry. The switch surfactants reported in the literature mainly use CO2 / N2, redox, light, heat, pH and physical magnetic field as switch means. Under the control of these switch means, the hydrophile-lipophile balance (HLB value) of the surfactant undergoes a significant reversible change, resulting in a corresponding significant reversible change in the surface (interface) activity of the surfactant, so that the surfactant exhibits a reversible "on" and "off" transition behavior. People figuratively name this type of surfactant whose surface (interface) properties can undergo reversible stress changes under the action of factors such as CO2 / N2, redox, light, heat, pH and physical magnetic field as switch surfactants. From the perspective of surfactant categories, carboxylate, sulfate, sulfonate, betaine and non-ionic switch surfactants have been reported, while phosphate surfactants with switch characteristics have not been publicly reported.
[0003] In addition, currently, surfactants in both industrial and civil and personal care fields cannot be recycled and reused after use. Most of these large amounts of used surfactants eventually enter the environment, which not only puts a serious burden on the ecological environment, but also wastes a large amount of carbonaceous resources, because the vast majority of current surfactants are derived from chemical products with carbonaceous resources such as petroleum as raw materials and artificial synthesis. Therefore, if the used surfactants can be effectively recycled and reused, there is no doubt that it can not only greatly alleviate the burden on the natural environment, but also save an astonishing amount of carbonaceous resources. To this end, the inventors have reported "precipitation-dissolution" switch surfactants (Langmuir, 2020, 36, 3514−3521; ACS Sustainable Chem. Eng., 2018, 6,4981−4986; Chem. Eng. J., 2021, 417, 129316; Chem. Eng. J., 2023, 458, 141297). "Precipitation-dissolution" switch surfactants are also a type of switch surfactants. The principle is that when the surfactant is in a dissolved state, it can normally exert its surface activity, emulsification, foaming, solubility enhancement and other properties. When the surfactant is in a precipitated state, it cannot normally exert its surface activity, emulsification, foaming, solubility enhancement and other properties. What is more important is that when the "precipitation-dissolution" switch surfactant is in a "precipitated" state, it appears in a closed state, which provides the recovery and reuse of the surfactant with the feature of easy separation and recovery that other types of switch surfactants do not have. The "precipitation-dissolution" switch surfactants that have been reported mainly include sulfates, sulfonates and betaines, while there has been no public report on phosphate-type "precipitation-dissolution" switch surfactants. Phosphate-type surfactants have excellent properties such as mildness, low irritation and degradability, and are widely used in textiles, leather, household and personal care products. However, due to concerns about environmental problems such as eutrophication caused by phosphorus in water bodies, people are eager to be able to efficiently recover phosphate-type surfactants after use.
[0004] In view of the above-mentioned technical status quo on phosphate-type surfactants, the present invention proposes a method for regulating the solubility of disodium monotetradecyl phosphate by pH, creatively utilizing the reversible change of pH to achieve the reversible conversion between disodium monotetradecyl phosphate and monosodium monotetradecyl phosphate, effectively changing the solubility of disodium monotetradecyl phosphate, and realizing the recovery and reuse of disodium monotetradecyl phosphate from micellar aqueous solution, emulsion and high internal phase emulsion in the form of monosodium monotetradecyl phosphate precipitate. Since the "precipitation-dissolution" switch surfactants previously reported by the inventors (Langmuir, 2020, 36, 3514−3521; ACS Sustainable Chem. Eng., 2018, 6, 4981−4986; Chem. Eng. J., 2021, 417, 129316; Chem. Eng. J., 2023, 458, 141297) are not conventional surfactants and do not involve phosphate-type surfactants, while disodium monotetradecyl phosphate is a conventional traditional surfactant, these are the most prominent differences between the technology of the present invention and the technology in the literature. In addition, the present invention has the beneficial effect that, in addition to being able to recover and reuse disodium monotetradecyl phosphate from micellar solutions, disodium monotetradecyl phosphate can also be recovered and reused from high internal phase emulsions with relatively high viscosity, and the recovered and regenerated disodium monotetradecyl phosphate still maintains the excellent performance of forming a high internal phase emulsion, while the literature technology does not involve the content of recovering surfactants from high internal phase emulsions. In addition, the method provided by the present invention for controlling the solubility of disodium monotetradecyl phosphate by pH generally has a recovery rate of not less than 98% for disodium monotetradecyl phosphate, while the recovery rate of sulfate-type "precipitation-dissolution" switch surfactants in the literature is only 90.8% (ACS Sustainable Chem. Eng., 2018, 6, 4981−4986), and the recovery rate of sulfonate-type "precipitation-dissolution" switch surfactants is 92~96% (Chem. Eng. J., 2021, 417, 129316; Chem. Eng. J., 2023, 458, 141297). The structural formulas of monosodium monotetradecyl phosphate and disodium monotetradecyl phosphate are shown in the figure below. Sodium monotetradecyl phosphate, Disodium monotetradecyl phosphate. Summary of the invention
[0005] The invention aims to provide a method for regulating the solubility of disodium monotetradecyl phosphate by pH in view of the current lack of research on salts of monoalkyl phosphates with different valence states, and to achieve reversible conversion between disodium monotetradecyl phosphate and monosodium monotetradecyl phosphate by reversible change of pH, so as to effectively change the solubility of disodium monotetradecyl phosphate and achieve recovery and reuse of disodium monotetradecyl phosphate from micellar aqueous solution, emulsion and high internal phase emulsion in the form of monosodium monotetradecyl phosphate precipitation.
[0006] Furthermore, the reversible conversion between disodium monotetradecyl phosphate and monosodium monotetradecyl phosphate by reversible change of pH refers to adjusting the pH to 6.3 with one of hydrochloric acid, phosphoric acid and sulfuric acid to convert disodium monotetradecyl phosphate into monosodium monotetradecyl phosphate.
[0007] Furthermore, the reversible conversion between disodium monotetradecyl phosphate and monosodium monotetradecyl phosphate by reversible change of pH refers to adjusting the pH to a range of 11.5 to 14.0 with sodium hydroxide to convert monosodium monotetradecyl phosphate into disodium monotetradecyl phosphate, and the preferred pH value is 11.5.
[0008] Furthermore, the solubility of disodium monotetradecyl phosphate is effectively changed, which means that the Krafft temperature (K T ) is about 0.3 °C, is water soluble, while the K T About 47.9 °C, poor water solubility.
[0009] Furthermore, the micellar aqueous solution refers to a micellar aqueous solution of disodium monotetradecyl phosphate.
[0010] Furthermore, the emulsion refers to an emulsion formed by using disodium monotetradecyl phosphate as an emulsifier and water and one of alkane, jojoba oil, isopropyl myristate, sunflower kernel oil, and dimethicone.
[0011] Furthermore, the high internal phase emulsion refers to a viscous emulsion with an oil phase volume percentage of 85% formed by disodium monotetradecyl phosphate as an emulsifier and one of alkanes, jojoba oil, isopropyl myristate, sunflower oil, and dimethicone and water.
[0012] Furthermore, the recovery and reuse refers to recovering disodium monotetradecyl phosphate in the form of monosodium monotetradecyl phosphate, and then reacting monosodium monotetradecyl phosphate with sodium hydroxide in an aqueous solution and maintaining the pH of the aqueous solution in the range of 11.5 to 14.0, with a preferred pH value of 11.5.
[0013] The method of the present invention has the following advantages over the prior art: 1. The results of the present invention prove that the K of monotetradecyl phosphate disodium salt T It is a low-lying anionic surfactant with good water solubility, high surface activity and good emulsification and solubilization ability, while monosodium monotetradecyl phosphate is not a surfactant in the traditional sense.
[0014] 2. The method for controlling the solubility of disodium monotetradecyl phosphate by pH provided by the present invention can be applied to the recovery of disodium monotetradecyl phosphate from micellar aqueous solutions, emulsions of various oil phases and high internal phase emulsions of various oil phases.
[0015] 3. The method for pH regulation of the solubility of disodium monotetradecyl phosphate provided by the present invention has mild reaction conditions, fast response speed, good reversibility and controllability, good recovery effect, and a recovery rate of not less than 98%.
[0016] 4. The monosodium monotetradecyl phosphate recovered by the technology of the present invention is regenerated to obtain disodium monotetradecyl phosphate, which still maintains the excellent performance of forming a high internal phase emulsion. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the monotetradecyl phosphate synthesized in Example 1 of the present invention.
[0018] Figure 2 This is the mass spectrum (positive ion mode) of the monotetradecyl phosphate synthesized in Example 1 of the present invention.
[0019] Figure 3 The acid-base titration curve of the monotetradecyl phosphate synthesized in Examples 1 and 2 of the present invention is shown.
[0020] Figure 4 This is a diagram showing the effect of reversibly regulating the water solubility of disodium monotetradecyl phosphate by pH in Example 4 of the present invention. DETAILED DESCRIPTION
[0021] The effects and benefits of the method for controlling the solubility of disodium monotetradecyl phosphate by pH provided by the present invention are further described below through specific examples.
[0022] Example 1: Synthesis of Monotetradecyl Phosphate First, benzene was dried with calcium hydride to remove water, and then the benzene was distilled to obtain anhydrous benzene. 12.9 g of pyrophosphoric acid (0.03 mol) was added to a 500 mL round-bottom flask, followed by 7.1 g of tetradecanol (0.03 mol) and 100 mL of freshly distilled benzene. The mixture was stirred continuously for 48 hours at 25°C using a mechanical stirrer. After the reaction was stopped, 50 mL of deionized water was added and heated to reflux for 4 hours. After cooling, 100 mL of ether was added and transferred to a separatory funnel. After separating the aqueous phase, the organic phase was washed with 50 mL of deionized water for 3 times. The organic phase was slowly dripped into an aqueous solution containing excess sodium hydroxide, and an appropriate amount of ether was added in the middle to reduce the viscosity, and the pH of the aqueous phase was maintained at about 13.5. After the organic phase was separated, the pH of the aqueous phase was adjusted to about 0.5 using concentrated hydrochloric acid, and about 100 mL of ether was added. After the aqueous phase was separated, the organic phase was washed 2 to 3 times with water at a pH of 0.5. Finally, the organic phase was transferred to a round-bottom flask and rotary evaporated to obtain a light yellow solid, which was then placed in a vacuum drying oven and dried at 30 °C to obtain a light yellow crude product. Finally, the crude product was recrystallized three times with n-hexane, and after removing the n-hexane, the final product, monotetradecyl phosphate (white glossy solid), was obtained, with a yield of about 84.1%.
[0023] The hydrogen nuclear magnetic resonance spectrum and mass spectrum of the product monotetradecyl phosphate in positive ion mode are shown in Figure 1 and Figure 2 , the spectrum analysis is as follows: Depend on Figure 1 It can be seen that the signal of methyl H is near 0.88ppm, the signal of 11 methylene H is near 1.26ppm, the signal of methylene H is near 1.69ppm, the signal of methylene H is near the methylene of phosphate group, the signal of methylene H is near 4.06ppm, the signal of two hydroxyl H on phosphate group is at 6.63ppm, and the integral ratio of the above signal areas is 3:21.7:2:2:2.3, which is very close to the theoretical value of the molecular structure of monotetradecyl phosphate.
[0024] Depend on Figure 2 It can be seen that the relative molecular mass M of monotetradecyl phosphate is 294.3. Figure 2 The signals at m / z 295.2, 589.4, 883.6, 1177.8 and 1472.0 correspond to [M+H] + , [2M+H] + , [3M+H] + , [4M+H] + and [5M+H] + . Depend on Figure 1 and Figure 2The results show that the white glossy solid obtained in this example is monotetradecyl phosphate. The purity of the obtained monotetradecyl phosphate is about 98.9% when analyzed by phosphomolybdenum blue ultraviolet spectrophotometry.
[0025] Example 2: Synthesis of Monotetradecyl Phosphate First, benzene was dried with calcium hydride to remove water, and then the benzene was distilled to obtain anhydrous benzene. 175.7 g of pyrophosphoric acid (0.44 mol) was added to a 500 mL round-bottom flask, followed by 80.3 g of tetradecanol (0.37 mol) and 200 mL of freshly distilled benzene after calcium hydride removal. The mixture was stirred continuously for 96 hours using a mechanical stirrer, and the temperature of the reaction was controlled at 20-25 °C throughout the reaction. After the reaction was stopped, 100 mL of deionized water was added and heated to reflux for 4 hours. After cooling, 200 mL of ether was added and transferred to a separatory funnel. After separating the aqueous phase, the organic phase was washed three times with 50 mL of deionized water. The organic phase was slowly dripped into an aqueous solution containing excess sodium hydroxide, and an appropriate amount of ether was added in the middle to reduce the viscosity, and the pH of the aqueous phase was maintained at around 13.5. After the organic phase is separated, the pH of the aqueous phase is adjusted to about 0.5 with concentrated hydrochloric acid, and about 200 mL of ether is added. After the aqueous phase is separated, the organic phase is washed three times with water at a pH of 0.5. Finally, the organic phase is transferred to a round-bottom flask and rotary evaporated to obtain a light yellow viscous paste, which is then placed in a vacuum drying oven and dried at 30°C to obtain a slightly yellow crude product. Finally, the crude product is recrystallized three times with n-hexane, and the final product, monotetradecyl phosphate (white shiny solid), is obtained after removing n-hexane, with a yield of about 88.2%. The hydrogen nuclear magnetic resonance spectrum and mass spectrum of the product are respectively Figure 1 and Figure 2 Similarly, the purity of the obtained monotetradecyl phosphate was about 99.1% by phosphomolybdenum blue ultraviolet spectrophotometry.
[0026] Example 3: Preparation of Monosodium Monotetradecyl Phosphate and Disodium Monotetradecyl Phosphate in Aqueous Solution A 0.005 mol / L monotetradecyl phosphate solution was prepared with a mixed solution of ethanol and water in a volume ratio of 3:1, and then a 0.01 mol / L sodium hydroxide solution was prepared with a mixed solution of ethanol and water in a volume ratio of 3:1. The monotetradecyl phosphate solution was dripped with sodium hydroxide solution at a constant temperature of 25°C. A glass pH electrode was used to monitor the pH of the mixed solution during the titration process, and the volume of the dripped sodium hydroxide solution and the change in the solution pH were recorded. The titration was stopped until the pH of the dripped solution was about 13 and the pH of the solution did not change much with the increase of the added sodium hydroxide, and a titration curve was obtained, as shown in FIG. Figure 3. The pKa1 and pKa2 of monotetradecyl phosphate are about 4.1 and 8.5, respectively. According to the pH-distribution coefficient relationship curve, when the pH of the aqueous solution is 6.3, the molar percentage of monotetradecyl phosphate monosodium reaches the maximum value (about 98.9%). After removing the solvent and drying, monotetradecyl phosphate monosodium can be obtained; when the pH of the aqueous solution is in the range of 11.5-14.0, the molar percentage of monotetradecyl phosphate disodium is as high as 99.9%. Considering that the molar percentage of monotetradecyl phosphate disodium is as high as 99.9% when the pH is 11.5, the pH corresponding to obtaining monotetradecyl phosphate disodium is preferably 11.5. After removing the solvent and drying, monotetradecyl phosphate disodium can be obtained. The purity of the obtained monotetradecyl phosphate monosodium and monotetradecyl phosphate disodium is about 99.1% and 99.3%, respectively. The Krafft temperature of disodium monotetradecyl phosphate was determined by visual observation to be about 0.3°C, so disodium monotetradecyl phosphate has good water solubility. The critical micelle concentration of disodium monotetradecyl phosphate was determined to be about 1.9×10 -2 mol / L, the interfacial tension between petroleum ether and water with a boiling range of 90-120 degrees Celsius can be reduced to 11.4 mN / m, which shows that the surface and interfacial activity of disodium monotetradecyl phosphate is relatively high. However, the Krafft temperature of monosodium monotetradecyl phosphate is as high as about 47.9°C. Therefore, monosodium monotetradecyl phosphate has poor water solubility, cannot form micelles in aqueous solution, and cannot significantly reduce the oil-water interfacial tension between water and petroleum ether.
[0027] Example 4: pH reversible regulation of water solubility of disodium monotetradecyl phosphate In this example, the monotetradecyl phosphate disodium obtained in Example 3 was used as the starting material, and the pH of the monotetradecyl phosphate disodium aqueous solution was adjusted alternately with sodium hydroxide and hydrochloric acid, and then K was measured respectively. T The technical process and effect of pH reversible regulation of the water solubility of disodium monotetradecyl phosphate are further explained.
[0028] A 1.0% mass percent, pH 11.5 aqueous solution of disodium monotetradecyl phosphate was prepared. The solution was clear and transparent at room temperature. After adjusting the pH value of the solution to 6.3 with HCl, a precipitate was observed within 1 minute. At this time, the measured K TThe temperature of the solution was about 48.1 °C, which was because at a pH of 6.3, the water-soluble monotetradecyl phosphate disodium was converted into the water-insoluble monotetradecyl phosphate monosodium; the pH of the solution was adjusted to 11.5 with sodium hydroxide, and the insoluble matter in the solution disappeared, and the entire solution became clear and transparent within 1 minute, because at a pH of 11.5, the water-insoluble monotetradecyl phosphate monosodium was converted into the water-soluble monotetradecyl phosphate disodium; this shows that the water solubility of monotetradecyl phosphate disodium can be reversibly converted between the two states of water-soluble and water-insoluble by reversibly adjusting the pH; further, the pH of the solution was reversibly converted between 6.3 and 11.5 by alternating hydrochloric acid and sodium hydroxide, and the K of monotetradecyl phosphate disodium (or monosodium) was T It also shows periodic changes accordingly. The results are shown in Figure 4 It can be seen that the pH reversible regulation of the water solubility of disodium monotetradecyl phosphate is relatively good and can be cycled at least 10 times.
[0029] Example 5: pH reversible regulation of water solubility of disodium monotetradecyl phosphate In this example, the disodium monotetradecyl phosphate obtained in Example 3 was used as a starting material. On the basis of Example 4, sulfuric acid and phosphoric acid were combined with sodium hydroxide to alternately adjust the pH of the disodium monotetradecyl phosphate aqueous solution, and the effect of reversibly regulating the water solubility of disodium monotetradecyl phosphate was further investigated.
[0030] Prepare a 1.0% mass percentage, pH 11.5 aqueous solution of disodium monotetradecyl phosphate. This solution is clear and transparent at room temperature. After adjusting the pH value of the solution to 6.3 with sulfuric acid, precipitation can be observed within 1 minute. At this time, the measured K T The temperature of the solution was about 48.2 °C, which was because at a pH of 6.3, the water-soluble monotetradecyl phosphate disodium was converted into the water-insoluble monotetradecyl phosphate monosodium; the pH of the solution was adjusted to 11.5 with sodium hydroxide, and the insoluble matter in the solution disappeared, and the entire solution became clear and transparent within 1 minute, because at a pH of 11.5, the water-insoluble monotetradecyl phosphate monosodium was converted into the water-soluble monotetradecyl phosphate disodium, which showed that the water solubility of monotetradecyl phosphate disodium can be reversibly adjusted by a combination of sulfuric acid and sodium hydroxide to reversibly convert between the two states of water-soluble and water-insoluble; further, the pH of the solution can be reversibly converted between 6.3 and 11.5 by alternating sulfuric acid and sodium hydroxide, respectively, and the K of monotetradecyl phosphate disodium (or monosodium) T It also shows periodic changes accordingly. Figure 4 Similarly, it can be seen that the reversibility of regulating the water solubility of disodium monotetradecyl phosphate by adjusting pH using a combination of sulfuric acid and sodium hydroxide is also good, and can be cycled at least 10 times.
[0031] Similar results were obtained by using a combination of phosphoric acid and sodium hydroxide according to the above process, indicating that the reversibility of adjusting the water solubility of disodium monotetradecyl phosphate by adjusting pH using a combination of phosphoric acid and sodium hydroxide is also good, and it can be cycled at least 10 times.
[0032] Example 6: Recovery of monosodium monotetradecyl phosphate from aqueous micellar solution and regeneration of disodium monotetradecyl phosphate In this example, the monotetradecyl phosphate disodium salt obtained in Example 3 was used as the starting material, and the critical micelle concentration of monotetradecyl phosphate disodium was measured to be about 1.9×10 -2 mol / L. Therefore, when a micellar aqueous solution of disodium monotetradecyl phosphate with a mass percentage of 2.0% (0.06 mol / L) and a pH of 11.5 was prepared, and the pH value of the solution was adjusted to 6.3 with HCl, sulfuric acid and phosphoric acid, monosodium monotetradecyl phosphate precipitation could be observed within 1 minute. After the precipitation was complete, the precipitate was separated by filtration. After drying, the recovery rates of monosodium monotetradecyl phosphate were 98.3%, 98.2% and 98.5% respectively, based on the percentage of the amount of disodium monotetradecyl phosphate. It can be seen that the type of acid used to adjust the pH of the solution to 6.3 has no obvious adverse effect on the recovery effect of monosodium monotetradecyl phosphate.
[0033] According to the mass percentage of 1.0%, the recovered monosodium tetradecyl phosphate was neutralized with sodium hydroxide in an aqueous solution and the pH was maintained at 11.5. The monosodium tetradecyl phosphate was observed to be completely dissolved at room temperature, and K T The value is about 0.3°C, indicating that the water-insoluble monosodium monotetradecyl phosphate is completely regenerated into water-soluble disodium monotetradecyl phosphate; the solution is dyed with pinacol cyanol chloride, and the solution appears blue, proving that there are micelles of disodium monotetradecyl phosphate in the solution. It can be seen that the monosodium monotetradecyl phosphate recovered by adjusting the pH to 6.3 with HCl, sulfuric acid and phosphoric acid can all be regenerated into water-soluble disodium monotetradecyl phosphate.
[0034] Example 7: Recovery of disodium monotetradecyl phosphate from emulsion In this embodiment, the monotetradecyl phosphate disodium salt obtained in Example 3 is used as an emulsifier for the emulsion. In this embodiment, the emulsion includes two types: emulsion and high internal phase emulsion. The oil phases used in this embodiment are petroleum ether, jojoba oil, isopropyl myristate, sunflower oil and dimethyl silicone oil with a boiling range of 90-120°C. The configuration method of the emulsion and the high internal phase emulsion in this embodiment is to mix the monotetradecyl phosphate disodium aqueous solution with a mass percentage of 2.0% and a pH of 11.5 with the oil phase according to a certain volume ratio, and then homogenize it for 1 minute at a speed of 1000 rpm in a high-speed disperser to obtain the emulsion and high internal phase emulsion of this embodiment. The high internal phase emulsion described in this embodiment refers to an emulsion with an oil phase volume percentage of 85%, and the emulsion described in this embodiment refers to an emulsion with an oil phase volume percentage of 50%. After testing, the types of the emulsion and the high internal phase emulsion obtained in this embodiment are both water-in-oil type, and all emulsions can be observed at room temperature to be stable for at least 45 days without demulsification.
[0035] According to the recovery method described in Example 6, all the disodium monotetradecyl phosphate in the emulsion and the high internal phase emulsion in this example can be recovered in the form of monosodium monotetradecyl phosphate, and the recovery rate is not less than 98%. According to the regeneration method described in Example 6, all the recovered water-insoluble monotetradecyl phosphate in this example can be regenerated into water-soluble disodium monotetradecyl phosphate, and K T Within the range of 0.31±0.02°C.
[0036] The regenerated disodium monotetradecyl phosphate was configured into an aqueous solution with a pH of 11.5 and a mass fraction of 2.0%. Dodecane was used as the oil phase, and the mixture was mixed according to different oil phase / water solution volume percentage ratios. The mixture was homogenized in a high-speed disperser at a speed of 1000 rpm for 1 minute to obtain emulsions and high internal phase emulsions with oil phase volume percentages of 61%, 78%, 83%, 88%, and 92%, respectively. The obtained emulsions were all oil-in-water emulsions and stored at room temperature for at least 45 days without demulsification, and the high internal phase emulsion with an oil phase volume percentage of 92% could be stable for at least 101 days without demulsification. The high internal phase emulsion with an oil phase volume percentage of 92% was centrifuged at a speed of 12000 rpm for 5 minutes, and the emulsion had no demulsification phenomenon; after being placed at 4°C, 25°C, 45°C, 65°C, and 85°C for 10 hours, and then returned to room temperature for observation, there was no obvious demulsification.
[0037] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Any person familiar with the present invention can easily change or replace the components after the present invention is disclosed, and all technical improvements that do not depart from the present invention should be included in the scope of the claims of the present invention.
Claims
1. A method for regulating the solubility of disodium monotetradecyl phosphate by pH, characterized in that: The invention discloses a method for realizing the reversible conversion between disodium monotetradecyl phosphate and monosodium monotetradecyl phosphate by utilizing the reversible change of pH, thereby changing the solubility of disodium monotetradecyl phosphate.
2. The method according to claim 1, characterized in that The pH is adjusted to 6.3 with one of hydrochloric acid, phosphoric acid and sulfuric acid to achieve conversion of disodium monotetradecyl phosphate into monosodium monotetradecyl phosphate.
3. The method according to claim 1, characterized in that The pH is adjusted to a range of 11.5 to 14.0 with sodium hydroxide to convert monosodium monotetradecyl phosphate into disodium monotetradecyl phosphate, with the preferred pH value being 11.
5.
4. The method according to claim 1, characterized in that: The Krafft temperature of the disodium monotetradecyl phosphate is 0.3°C, while the Krafft temperature of the monosodium monotetradecyl phosphate is 47.9°C.
5. The method according to claim 1 is used for recovering disodium monotetradecyl phosphate from a micellar aqueous solution of disodium monotetradecyl phosphate, an emulsion containing disodium monotetradecyl phosphate or a high internal phase emulsion.
6. The use according to claim 5, characterized in that: The emulsion is an emulsion formed by using disodium monotetradecyl phosphate as an emulsifier and water and one of alkane, jojoba oil, isopropyl myristate, sunflower kernel oil and dimethyl silicone oil.
7. The use according to claim 5, characterized in that: The high internal phase emulsion is a viscous emulsion with an oil phase volume percentage of 85%, which is formed by disodium monotetradecyl phosphate as an emulsifier and is respectively composed of alkane, jojoba oil, isopropyl myristate, sunflower kernel oil, dimethyl silicone oil and water.
8. The use according to claim 5, characterized in that: After the disodium monotetradecyl phosphate is recovered in the form of monosodium monotetradecyl phosphate, sodium hydroxide is used to react with the monosodium monotetradecyl phosphate in an aqueous solution and the pH of the aqueous solution is maintained at 11.5.