Method for recovering diethyl phosphate sodium salt in Wittig-Honager reaction wastewater

Abstract

The invention discloses a method for recovering diethyl phosphate sodium salt in Wittig-Honeyer reaction wastewater, which comprises the following steps: adding an acid solution into Wittig-Honeyer reaction wastewater to obtain an acidic mixed solution, converting diethyl phosphate sodium salt into diethyl phosphate, adding an extracting agent into the acidic mixed solution to transfer diethyl phosphate into an organic phase, and carrying out solid-liquid separation, thereby obtaining the diethyl phosphate sodium salt in the Wittig-Honeyer reaction wastewater. Performing liquid separation to obtain an organic phase containing diethyl phosphate, adding an alkaline solution to obtain an alkaline mixed solution, re-converting diethyl phosphate into sodium diethyl phosphate, performing liquid separation to obtain a water phase containing sodium diethyl phosphate, adding an alcohol solvent, precipitating inorganic salt, filtering to obtain a filtrate containing sodium diethyl phosphate, distilling the filtrate to obtain a sodium diethyl phosphate solid, and drying to obtain the sodium diethyl phosphate. The purity and the recovery rate of the diethyl phosphate sodium salt product obtained by the recovery method are improved, the operation is simple, the energy consumption is low, the production cost is reduced, and the subsequent deep development and utilization of the diethyl phosphate sodium salt can be met.

Description

Technical Field

[0001] The invention relates to the technical field of treatment and recovery of phosphorus-containing wastewater in Wittig-Horner reaction, and in particular to a method for recovering sodium diethyl phosphate in Wittig-Horner reaction wastewater. Background Art

[0002] The Horner–Wadsworth–Emmons (HWE) reaction, also commonly known as the Wittig-Horner reaction, is an important organic synthesis reaction for preparing olefins. It uses stable phosphonate carbon anions instead of phosphorus ylides to react with aldehydes and ketones to generate olefins. Its main product, E-type olefins, is widely used in the synthesis of pesticide intermediates, medicines, and fluorescent whitening agents. Phosphate compounds will be partially converted into diethyl phosphate sodium salt in the Wittig-Horner reaction, and diethyl phosphate sodium salt as a by-product can be recycled and reused. Therefore, the recovery of diethyl phosphate sodium salt, a by-product of the Wittig-Horner reaction, has become an important measure for enterprises to manage waste residues and improve economic benefits.

[0003] At present, the treatment and recovery of sodium diethyl phosphate in Wittig-Horner reaction wastewater still relies on traditional treatment methods. However, the use of a distillation method for solid-liquid separation alone has the problems of high material viscosity, similar physical properties of the components in the system, and low recovery rate and purity of sodium diethyl phosphate, which restricts the further development and utilization of sodium diethyl phosphate and has an adverse effect on large-scale treatment and recovery of sodium diethyl phosphate by enterprises. The byproduct sodium diethyl phosphate cannot be effectively recovered and utilized, which will not only cause a large amount of organic phosphorus resources to be wasted, but also lead to excessive chemical oxygen demand (COD) and total phosphorus in the Wittig-Horner reaction wastewater, increasing the difficulty of treating the Wittig-Horner reaction wastewater. Therefore, a method for recovering sodium diethyl phosphate from Wittig-Horner reaction wastewater is urgently needed, which can improve the recovery rate and purity of sodium diethyl phosphate and lay a foundation for the in-depth development and utilization of sodium diethyl phosphate. Summary of the invention

[0004] The object of the present invention is to provide a method for recovering sodium diethyl phosphate from waste water of Wittig-Horner reaction, so as to improve the recovery rate and purity of sodium diethyl phosphate recovered from waste water of Wittig-Horner reaction.

[0005] In order to solve the above technical problems, the present invention provides a method for recovering sodium diethyl phosphate in the wastewater of Wittig-Hornal reaction, comprising the following steps:

[0006] Adding an acid solution to the Wittig-Hornal reaction wastewater containing sodium diethyl phosphate to obtain an acidic mixed solution, and stirring the acidic mixed solution at a temperature-insulated state;

[0007] Adding an extractant to the acidic mixed solution, stirring, standing and separating the layers to obtain an aqueous phase containing an inorganic salt and an organic phase containing diethyl phosphate;

[0008] Adding an alkaline solution to the organic phase containing diethyl phosphate to obtain an alkaline mixed solution, stirring and keeping warm, standing the solution to separate the layers, and separating the layers to obtain an aqueous phase containing sodium diethyl phosphate and an organic phase containing the extractant;

[0009] adding an alcohol solvent to the aqueous phase containing sodium diethyl phosphate to precipitate an inorganic salt, and filtering to obtain a filtrate containing sodium diethyl phosphate;

[0010] Distilling the filtrate containing sodium diethyl phosphate to obtain sodium diethyl phosphate solid and a distillate containing the alcohol solvent;

[0011] The sodium diethyl phosphate solid is crushed to obtain a sodium diethyl phosphate product.

[0012] It should be noted in the scheme that the acid solution is one or more of hydrochloric acid solution, sulfuric acid solution, nitric acid solution and phosphoric acid solution.

[0013] It should be noted in the scheme that the alkaline solution is one or more of sodium hydroxide solution, sodium bicarbonate solution and sodium carbonate solution.

[0014] It should be noted in the scheme that the extractant is one or more of dichloroethane, dichloromethane, chloroform, ethyl acetate and toluene.

[0015] It should be noted that the alcohol solvent is one or more of methanol solvent, ethanol solvent, isopropanol solvent and 1,3-butanediol solvent.

[0016] It is further worth noting that the mass ratio of the aqueous phase containing sodium diethyl phosphate to the alcohol solvent is 1:1-4.

[0017] As a preferred embodiment, the concentration of the acid solution is 20% to 50%, and the pH of the acidic mixed solution is 2 to 3.

[0018] As a preferred embodiment, the acidic mixed solution is kept warm and stirred for 3 to 4 hours at a temperature of 10 to 80°C.

[0019] As a preferred embodiment, the stirring time after adding the extractant is 0.5 to 3 hours.

[0020] As a preferred embodiment, the stirring temperature and stirring time of the alkaline mixed solution are 10-80° C. and 0.5-3 h.

[0021] Compared with the prior art, the method for recovering sodium diethyl phosphate in wastewater from a Wittig-Hornal reaction provided by the present invention has at least the following beneficial effects:

[0022] The acid solution is added to the wastewater of Wittig-Horner reaction containing sodium diethyl phosphate to obtain an acidic mixed solution, and the acidic mixed solution is stirred while being kept warm. Since the wastewater of Wittig-Horner reaction contains inorganic salts such as sodium hydroxide and sodium sulfate in addition to sodium diethyl phosphate, direct extraction of sodium diethyl phosphate will be mixed with other inorganic salt impurities. The sodium diethyl phosphate in the wastewater of Wittig-Horner reaction can be converted into diethyl phosphate by adding the acid solution; an extractant is added to the acidic mixed solution, and the mixture is allowed to stand for stratification after stirring, and the aqueous phase containing inorganic salts and the organic phase containing diethyl phosphate are separated to obtain an aqueous phase containing inorganic salts and an organic phase containing diethyl phosphate. The diethyl phosphate in the wastewater of Wittig-Horner reaction can be transferred to the organic phase by the extractant, and the phosphorus content of the inorganic salt water phase is detected to meet the standard, and then the inorganic salt product is obtained by distillation and concentration; an alkali solution is added to the organic phase containing diethyl phosphate to obtain an alkaline mixed solution. The invention discloses a method for preparing a sodium diethyl phosphate product by mixing the diethyl phosphate solution, converting diethyl phosphate back into sodium diethyl phosphate, and then standing and stratifying after heat preservation and stirring. The aqueous phase containing sodium diethyl phosphate and the organic phase containing the extractant are separated, and the organic phase containing the extractant can be recycled after distillation and concentration; an alcohol solvent is added to the aqueous phase containing sodium diethyl phosphate, and after the inorganic salt is precipitated, a filtrate containing sodium diethyl phosphate is obtained by filtration, and the filtrate containing sodium diethyl phosphate is distilled to obtain a sodium diethyl phosphate solid and a distillate containing an alcohol solvent, and after the phosphorus content of the distillate is detected to be normal, the alcohol solvent is recovered by distillation and separation for recycling, and the sodium diethyl phosphate solid is crushed to obtain a sodium diethyl phosphate product. The purity and recovery rate of the sodium diethyl phosphate product obtained by the recovery method are improved. At the same time, the method is simple to operate, has low energy consumption, reduces production costs, and can meet the subsequent deep development and utilization of sodium diethyl phosphate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without inventiveness.

[0024] Figure 1 A flow chart of a method for recovering sodium diethyl phosphate from wastewater of a Wittig-Hornal reaction provided by the present invention;

[0025] Figure 2 The gas chromatogram of the sodium diethyl phosphate product obtained in Example 1 of the present invention after acid treatment. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings.

[0027] The core of the invention is to provide a method for recovering sodium diethyl phosphate from waste water of Wittig-Horner reaction, so as to improve the purity and recovery rate of sodium diethyl phosphate recovered from waste water of Wittig-Horner reaction.

[0028] Figure 1 A flow chart of a method for recovering sodium diethyl phosphate from wastewater of a Wittig-Hornal reaction provided by the present invention, Figure 2 The gas chromatogram of the diethyl phosphate sodium salt product obtained in Example 1 of the present invention after acid treatment is shown in FIG. Figure 1 to Figure 2 shown.

[0029] A method for recovering sodium diethyl phosphate from wastewater of a Wittig-Hornal reaction, see Figure 1 , including the following steps:

[0030] S1: adding an acid solution to the wastewater of the Wittig-Hornal reaction containing sodium diethyl phosphate to obtain an acidic mixed solution, and stirring the acidic mixed solution at a temperature of 10 to 80° C. Preferably, the acidic mixed solution is stirred at a temperature of 3 to 4 hours, and the temperature is 10 to 80° C. It should be noted that the acidic solution is one or more of a hydrochloric acid solution, a sulfuric acid solution, a nitric acid solution, and a phosphoric acid solution. Preferably, the acidic solution is one of a hydrochloric acid solution, a sulfuric acid solution, a nitric acid solution, and a phosphoric acid solution. The use of a single acid solution can make the generated inorganic salt a single inorganic salt, which is beneficial to the recovery and sale of the inorganic salt product. Of course, the use of a mixed acid solution can still achieve the effect of recovering the sodium diethyl phosphate product when a single acid solution is used. It is further worth noting that the concentration of the acid solution is 20% to 50%, and the pH of the acidic mixed solution is 2 to 3.

[0031] Since the wastewater from the Wittig-Horner reaction contains inorganic salts such as sodium hydroxide and sodium sulfate in addition to sodium diethyl phosphate, direct extraction of sodium diethyl phosphate will be mixed with other inorganic salt impurities. The addition of acid solution can convert sodium diethyl phosphate in the wastewater from the Wittig-Horner reaction into diethyl phosphate. The reaction equation is as follows:

[0032]

[0033] The organic phosphorus salt is converted into an organic salt by an acid solution, and the purity of the obtained diethyl phosphate sodium salt product can be improved through subsequent extraction, alkalization and other steps.

[0034] S2: adding an extractant to the acidic mixed solution. It should be noted that the extractant is one or more of dichloroethane, dichloromethane, chloroform, ethyl acetate and toluene. The extractant can transfer the diethyl phosphate in the acidic mixed solution to the organic phase. After stirring, the mixture is allowed to stand for stratification. Preferably, the stirring time is 0.5 to 3 hours. The aqueous phase containing inorganic salts and the organic phase containing diethyl phosphate are separated to obtain an aqueous phase containing inorganic salts and an organic phase containing diethyl phosphate. The phosphorus content of the aqueous phase containing inorganic salts is detected by the ammonium molybdate spectrophotometry method required by the national standard. If the phosphorus content is less than 20, it meets the standard and is transferred to the ordinary wastewater treatment process. The aqueous phase containing inorganic salts can be distilled and concentrated to obtain a saleable inorganic salt product. If the phosphorus content is higher than 20, it is necessary to add an appropriate amount of acid solution and extractant to the aqueous phase containing inorganic salts until the phosphorus content of the aqueous phase containing inorganic salts reaches the standard to ensure that sodium diethyl phosphate has been fully converted into diethyl phosphate. The organic phase containing diethyl phosphate is subjected to a subsequent alkalization step.

[0035] S3: Adding an alkaline solution to the organic phase containing diethyl phosphate to obtain an alkaline mixed solution, so that diethyl phosphate is reconverted into sodium diethyl phosphate. The reaction equation is as follows:

[0036]

[0037] It should be noted that the alkaline solution is one or more of sodium hydroxide solution, sodium bicarbonate solution and sodium carbonate solution. The alkaline mixed solution is stirred and allowed to stand for stratification. Preferably, the stirring temperature is 10 to 80° C. and the stirring time is 0.5 to 3 h. The liquids are separated to obtain an aqueous phase containing sodium diethyl phosphate and an organic phase containing an extractant. The organic phase containing the extractant can be recovered and reused after distillation and concentration, and the aqueous phase containing sodium diethyl phosphate is further subjected to subsequent treatment.

[0038] S4: adding an alcohol solvent to the aqueous phase containing sodium diethyl phosphate. It should be noted that the alcohol solvent is one or more of a methanol solvent, an ethanol solvent, an isopropanol solvent and a 1,3-butanediol solvent. It is further worth noting that the mass ratio of the aqueous phase containing sodium diethyl phosphate to the alcohol solvent is 1:1-4. After the inorganic salt is precipitated, filtering is performed to obtain a filtrate containing sodium diethyl phosphate. A small amount of inorganic salt generated by the acid-base neutralization reaction can be removed by adding an alcohol solvent and filtering.

[0039] S5: distilling the filtrate containing sodium diethyl phosphate to obtain sodium diethyl phosphate solid and distillate containing alcohol solvent, testing the phosphorus content of the distillate containing alcohol solvent to avoid the situation where the phosphorus content of the distillate is too high due to excessive distillation, and after the phosphorus content is measured to be normal, distilling and separating the distillate containing alcohol solvent to recover the alcohol solvent for application; crushing the sodium diethyl phosphate solid to obtain the final sodium diethyl phosphate product.

[0040] The invention simplifies the process for recovering sodium diethyl phosphate from waste water of a Wittig-Horner reaction. The purity and recovery rate of the sodium diethyl phosphate product obtained by the recovery method are improved. The method is simple to operate, consumes less energy, reduces production costs, and can meet the needs of subsequent deep development and utilization of sodium diethyl phosphate.

[0041] Example 1

[0042] 300g of Wittig-Horner reaction wastewater containing sodium diethyl phosphate was put into a 500ml four-necked flask, and 170g of 20% hydrochloric acid aqueous solution was slowly added dropwise to adjust the pH of the Wittig-Horner reaction wastewater to 2 to obtain an acidic mixed solution with a pH of 2. The acidic mixed solution was kept warm and stirred at 40°C for 3 hours, 160g of dichloromethane was added for extraction, and after stirring for 2 hours, the mixture was allowed to stand and separate to obtain an aqueous phase containing sodium chloride and an organic phase containing diethyl phosphate. The phosphorus content of the aqueous phase containing sodium chloride was measured by ammonium molybdate spectrophotometry to be 5mg / L, which was less than 20mg / L and met the standard. The mixture was transferred to a common wastewater treatment process, and a sodium chloride product was obtained by distillation and concentration. 80g of 30% NaOH aqueous solution was added to the organic phase containing diethyl phosphate to obtain an alkaline mixed solution. The alkaline mixed solution was kept warm and stirred at 50°C for 3 hours, and the aqueous phase containing sodium diethyl phosphate and the organic phase containing dichloromethane were separated. The organic phase of methane is concentrated by distillation, and the dichloromethane-containing organic phase is recovered and applied. The aqueous phase containing sodium diethyl phosphate is 150g. 150g of methanol solvent is added to the aqueous phase containing sodium diethyl phosphate. After sodium chloride is precipitated, the filtrate containing sodium diethyl phosphate is obtained by suction filtration. The filtrate containing sodium diethyl phosphate is subjected to reduced pressure distillation to obtain sodium diethyl phosphate solid and a distillate containing methanol solvent. The phosphorus content of the distillate containing methanol solvent is 3mg / L measured by ammonium molybdate spectrophotometry, which is in a normal amount. The methanol solvent is recovered by distillation and applied, and the sodium diethyl phosphate solid is crushed to obtain 65g of sodium diethyl phosphate product. The sodium diethyl phosphate product is a white solid. This embodiment is the best embodiment. The sodium diethyl phosphate product recovered in this embodiment is subjected to gas chromatography analysis after acid treatment, and compared with the standard sample diethyl phosphate for verification. It can be seen that the purity of the sodium diethyl phosphate product recovered in Example 1 is 93.2%, see Figure 2 It should be noted that, in order to ensure the analytical effect of the gas chromatography analysis chart, acid treatment of the sodium salt of diethyl phosphate product to convert it into diethyl phosphate and then gas chromatography analysis is a commonly used analytical method in this field.

[0043] The total phosphorus content test results of the Wittig-Hornal reaction wastewater, the aqueous phase containing sodium chloride, the distillate containing the methanol solvent, the diethyl phosphate sodium salt product and the sodium chloride product in Example 1 are shown in Table 1:

[0044] Table 1 Detection of total phosphorus content in reaction wastewater and treated water layer in Example 1

[0045]

[0046] As can be seen from the data in Table 1, the total phosphorus content of the Wittig-Hornal reaction wastewater before recovery of diethyl phosphate sodium salt is 41000 mg / L; the total phosphorus content of the aqueous phase containing sodium chloride is 5 mg / L, and sodium diethyl phosphate has been fully converted into diethyl phosphate; the total phosphorus content of the distillate containing methanol solvent is 3 mg / L, which is a normal amount; the content of the recovered sodium chloride product is 99.5%, and the recovery rate of the diethyl phosphate sodium salt product recovered in Example 1 is 99% by calculation.

[0047] Example 2

[0048] 300g of Wittig-Horner reaction wastewater containing sodium diethyl phosphate was put into a 500ml four-necked flask, and 120g of 40% sulfuric acid aqueous solution was slowly added dropwise to adjust the pH of the Wittig-Horner reaction wastewater to 3 to obtain an acidic mixed solution with a pH of 3. The temperature of the acidic mixed solution was kept warm and stirred at 50°C for 4 hours, and 160g of ethyl acetate was added for extraction. After stirring for 3 hours, the mixture was allowed to stand and separate to obtain an aqueous phase containing sodium sulfate and an organic phase containing diethyl phosphate. The phosphorus content of the aqueous phase containing sodium sulfate was measured by ammonium molybdate spectrophotometry to be 6mg / L, which was less than 20mg / L and met the standard. The mixture was transferred to a common wastewater treatment process, and a sodium sulfate product was obtained by distillation and concentration. 100g of 30% sodium carbonate aqueous solution was added to the organic phase containing diethyl phosphate to obtain an alkaline mixed solution. The alkaline mixed solution was kept at 30° C. and stirred for 2 hours. The aqueous phase containing sodium diethyl phosphate and the organic phase containing ethyl acetate were separated. The organic phase containing ethyl acetate was concentrated by distillation. The ethyl acetate was recovered and reused. The aqueous phase containing sodium diethyl phosphate was weighed to obtain 170 g. 340 g of ethanol solvent was added to the aqueous phase containing sodium diethyl phosphate. After sodium sulfate was precipitated, the filtrate containing sodium diethyl phosphate was obtained by suction filtration. The filtrate containing sodium diethyl phosphate was subjected to reduced pressure distillation to obtain sodium diethyl phosphate solid and a distillate containing ethanol solvent. The phosphorus content of the distillate containing ethanol solvent was measured by ammonium molybdate spectrophotometry to be 4 mg / L, which was a normal amount. The ethanol solvent was recovered by distillation and reused. The sodium diethyl phosphate solid was crushed to obtain 62 g of sodium diethyl phosphate product. The sodium diethyl phosphate product was a white solid with a purity of 92.5%.

[0049] The total phosphorus content test results of the Wittig-Hornal reaction wastewater, the aqueous phase containing sodium sulfate, the distillate containing the ethanol solvent, the diethyl phosphate sodium salt product and the sodium sulfate product in Example 2 are shown in Table 2:

[0050] Table 2 Detection of total phosphorus content in reaction wastewater and treated water layer in Example 2

[0051]

[0052] As can be seen from the data in Table 2, the total phosphorus content of the Wittig-Hornal reaction wastewater before recovery of diethyl phosphate sodium salt was 41000 mg / L after detection; the total phosphorus content of the aqueous phase containing sodium sulfate was 6 mg / L, and sodium diethyl phosphate had been fully converted into diethyl phosphate; the total phosphorus content of the ethanol solvent distillate was 4 mg / L, which was normal; the content of the recovered sodium sulfate product was 99.6%, and the recovery rate of the diethyl phosphate sodium salt product recovered in Example 2 was 98.5% after calculation.

[0053] Example 3

[0054] 300g of Wittig-Horner reaction wastewater containing sodium diethyl phosphate was put into a 500ml four-necked flask, and 250g of 20% sulfuric acid aqueous solution was slowly added dropwise to adjust the pH of the Wittig-Horner reaction wastewater to 2.5 to obtain an acidic mixed solution with a pH of 2.5. The temperature of the acidic mixed solution was kept at 70°C and stirred for 3 hours, 160g of chloroform was added for extraction, and after stirring for 1 hour, the mixture was allowed to stand for stratification, and the aqueous phase containing sodium sulfate and the organic phase containing diethyl phosphate were separated to obtain an aqueous phase containing sodium sulfate and an organic phase containing diethyl phosphate. The phosphorus content of the aqueous phase containing sodium sulfate was measured by ammonium molybdate spectrophotometry to be 10mg / L, which was less than 20mg / L and met the standard. The aqueous phase was transferred to a common wastewater treatment process, and a sodium sulfate product was obtained by distillation and concentration. 160g of 15% NaOH aqueous solution was added to the organic phase containing diethyl phosphate to obtain an alkaline mixed solution. The method comprises the steps of: adding 200 g of sodium diethyl phosphate and 100 g of sodium phosphate distilled water, stirring the alkaline mixed solution at 60° C. for 1 hour, separating the liquid to obtain an aqueous phase containing sodium diethyl phosphate and an organic phase containing chloroform, distilling and concentrating the organic phase containing chloroform, recovering and reusing the chloroform, weighing 230 g of the aqueous phase containing sodium diethyl phosphate, adding 350 g of isopropanol solvent to the aqueous phase containing sodium diethyl phosphate, precipitating sodium sulfate, filtering to obtain a filtrate containing sodium diethyl phosphate, distilling the filtrate containing sodium diethyl phosphate under reduced pressure to obtain a sodium diethyl phosphate solid and a distillate containing isopropanol solvent, measuring the phosphorus content of the distillate containing isopropanol solvent by ammonium molybdate spectrophotometry to be 8 mg / L, which is a normal amount, distilling and recovering the isopropanol solvent for reusing, and crushing the sodium diethyl phosphate solid to obtain 66 g of sodium diethyl phosphate product, which is a white solid with a purity of 91.8%.

[0055] The total phosphorus content test results of the Wittig-Hornal reaction wastewater, the aqueous phase containing sodium sulfate, the distillate containing the isopropanol solvent, the sodium salt of diethyl phosphate and the sodium sulfate product in Example 3 are shown in Table 3:

[0056] Table 3 Detection of total phosphorus content in reaction wastewater and treated water layer in Example 3

[0057]

[0058] As can be seen from the data in Table 3, the total phosphorus content of the Wittig-Hornal reaction wastewater before recovery of diethyl phosphate sodium salt was 41000 mg / L after detection; the total phosphorus content of the aqueous phase containing sodium sulfate was 10 mg / L, and sodium diethyl phosphate had been converted into diethyl phosphate; the total phosphorus content of the distillate containing isopropanol solvent was 8 mg / L, which was in a normal amount, and the content of the recovered sodium sulfate product was 99.4%. The recovery rate of the diethyl phosphate sodium salt product recovered in Example 3 was calculated to be 98%.

[0059] Example 4

[0060] 300g of Wittig-Horner reaction wastewater containing sodium diethyl phosphate was put into a 500ml four-necked flask, and 120g of 50% nitric acid aqueous solution was slowly added dropwise to adjust the pH of the Wittig-Horner reaction wastewater to 3 to obtain an acidic mixed solution with a pH of 3, and the temperature of the acidic mixed solution was kept warm and stirred at 10°C for 4 hours, 150g of dichloroethane was added for extraction, and after stirring for 3 hours, the mixture was allowed to stand for stratification, and the aqueous phase containing sodium nitrite and the organic phase containing diethyl phosphate were separated to obtain an aqueous phase containing sodium nitrite and an organic phase containing diethyl phosphate. The phosphorus content of the aqueous phase containing sodium nitrite was measured by ammonium molybdate spectrophotometry to be 14mg / L, which was less than 20mg / L and met the standard, and the mixture was transferred to a common wastewater treatment process, and a sodium nitrite product was obtained by distillation and concentration. 250g of 20% sodium bicarbonate aqueous solution was added to the organic phase containing diethyl phosphate to obtain an alkaline mixed solution, and the temperature of the alkaline mixed solution was kept warm. The mixture was stirred at 10°C for 3 hours, and the aqueous phase containing sodium diethyl phosphate and the organic phase containing ethylene dichloride were separated to obtain an aqueous phase containing sodium diethyl phosphate and an organic phase containing ethylene dichloride. The organic phase containing ethylene dichloride was concentrated by distillation, and the ethylene dichloride was recovered and reused. The aqueous phase containing sodium diethyl phosphate was weighed to obtain 320 g. 1280 g of 1,3-butanediol solvent was added to the aqueous phase containing sodium diethyl phosphate. After sodium nitrite was precipitated, the filtrate containing sodium diethyl phosphate was obtained by suction filtration. The filtrate containing sodium diethyl phosphate was subjected to reduced pressure distillation to obtain sodium diethyl phosphate solid and a distillate containing 1,3-butanediol solvent. The phosphorus content of the distillate containing 1,3-butanediol solvent was 11 mg / L measured by ammonium molybdate spectrophotometry, which was in a normal amount. The 1,3-butanediol solvent was recovered by distillation and reused. The sodium diethyl phosphate solid was crushed to obtain 64 g of sodium diethyl phosphate product. The sodium diethyl phosphate product was a white solid with a purity of 91.3%.

[0061] The total phosphorus content test results of the Wittig-Hornal reaction wastewater, the aqueous phase containing sodium nitrite, the distillate containing 1,3-butanediol solvent, the diethyl phosphate sodium salt product and the sodium nitrite product in Example 4 are shown in Table 4:

[0062] Table 4 Detection of total phosphorus content in reaction wastewater and treated water layer in Example 4

[0063]

[0064] As can be seen from the data in Table 4, the total phosphorus content of the Wittig-Hornal reaction wastewater before recovery of diethyl phosphate sodium salt was 41000 mg / L after detection; the total phosphorus content of the aqueous phase containing sodium nitrite was 14 mg / L, and sodium diethyl phosphate had been fully converted into diethyl phosphate; the total phosphorus content of the distillate containing 1,3-butanediol solvent was 11 mg / L, which was in normal amount, and the content of the recovered sodium nitrite product was 91.3%. The recovery rate of the diethyl phosphate sodium salt product recovered in Example 4 was 97.8% after calculation.

[0065] Example 5

[0066] 300g of Wittig-Horner reaction wastewater containing sodium diethyl phosphate was put into a 500ml four-necked flask, and 300g of 30% phosphoric acid aqueous solution was slowly added dropwise to adjust the pH of the Wittig-Horner reaction wastewater to 2 to obtain an acidic mixed solution with a pH of 2. The temperature of the acidic mixed solution was kept at 80°C and stirred for 3 hours, 250g of toluene was added for extraction, and after stirring for 0.5 hours, the mixture was allowed to stand for stratification, and the aqueous phase containing sodium phosphate and the organic phase containing diethyl phosphate were obtained by separation. The phosphorus content of the aqueous phase containing sodium phosphate was 12mg / L measured by ammonium molybdate spectrophotometry, which was less than 20mg / L and met the standard. The mixture was transferred to a common wastewater treatment process, and a sodium phosphate product was obtained by distillation and concentration. 150g of 20% sodium carbonate aqueous solution was added to the organic phase containing diethyl phosphate to obtain an alkaline mixed solution. The method comprises the steps of: adding 220 g of the aqueous phase containing sodium diethyl phosphate to the aqueous phase containing sodium diethyl phosphate, and stirring the aqueous phase for 0.5 hours at a temperature of 80° C., and recovering the toluene for application. The aqueous phase containing sodium diethyl phosphate is weighed to obtain 220 g of the aqueous phase containing sodium diethyl phosphate. 350 g of methanol solvent is added to the aqueous phase containing sodium diethyl phosphate. After sodium phosphate is precipitated, the aqueous phase is filtered to obtain a filtrate containing sodium diethyl phosphate. The filtrate containing sodium diethyl phosphate is subjected to reduced pressure distillation to obtain a sodium diethyl phosphate solid and a distillate containing methanol solvent. The phosphorus content of the distillate containing methanol solvent is 9 mg / L as measured by ammonium molybdate spectrophotometry, which is in a normal amount. The methanol solvent is recovered by distillation for application. The sodium diethyl phosphate solid is crushed to obtain 64 g of a sodium diethyl phosphate product. The sodium diethyl phosphate product is a white solid with a purity of 91.5%.

[0067] The total phosphorus content test results of the Wittig-Hornal reaction wastewater, the aqueous phase containing sodium phosphate, the distillate containing methanol solvent, the diethyl phosphate sodium salt product and the sodium phosphate product in Example 5 are shown in Table 5:

[0068] Table 5 Detection of total phosphorus content in reaction wastewater and treated water layer in Example 5

[0069]

[0070] As can be seen from the data in Table 5, the total phosphorus content of the Wittig-Hornal reaction wastewater before recovery of diethyl phosphate sodium salt was 41000 mg / L after detection; the total phosphorus content of the sodium phosphate-containing aqueous phase was 12 mg / L, and sodium diethyl phosphate had been fully converted into diethyl phosphate; the total phosphorus content of the methanol solvent-containing distillate was 9 mg / L, which was in a normal amount, and the content of the recovered sodium phosphate product was 99%. The recovery rate of the diethyl phosphate sodium salt product recovered in Example 5 was calculated to be 98%.

[0071] In summary, it can be seen from Examples 1 to 5 that the method for recovering diethyl phosphate sodium salt from Wittig-Horner reaction wastewater provided by the present invention can ensure that the purity of the recovered diethyl phosphate sodium salt product is not less than 90%, which is conducive to the subsequent in-depth development and utilization of diethyl phosphate sodium salt. The content of the recovered inorganic salt products (sodium chloride product, sodium sulfate product, sodium nitrite product, sodium phosphate product) is higher than 99%, indicating that the separation effect of inorganic salt and diethyl phosphate sodium salt is good, and the recovery rate of diethyl phosphate sodium salt product is not less than 97%. It can be seen that compared with the existing treatment and recovery method, the method provided by the present invention has obvious advantages in recovering diethyl phosphate sodium salt from phosphorus-containing Wittig-Horner reaction wastewater.

[0072] The invention provides an acidic mixed solution by adding an acid solution to Wittig-Horner reaction wastewater containing sodium diethyl phosphate, converting the sodium diethyl phosphate in the reaction wastewater into diethyl phosphate, adding an extractant to the acidic mixed solution to transfer the diethyl phosphate in the Wittig-Horner reaction wastewater to an organic phase, separating the liquids to obtain an inorganic salt-containing aqueous phase and an organic phase containing diethyl phosphate, detecting that the phosphorus content of the inorganic salt-containing aqueous phase meets the standard and then transferring the phase to a common wastewater treatment process, adding an alkaline solution to the organic phase containing diethyl phosphate to obtain an alkaline mixed solution, converting the diethyl phosphate into sodium diethyl phosphate again, separating the liquids to obtain an aqueous phase containing sodium diethyl phosphate and an organic phase containing the extractant. The organic phase containing the extractant can be recycled after distillation and concentration, an alcohol solvent is added to the aqueous phase containing sodium diethyl phosphate, and then filtered to remove excess alkali solution to obtain a filtrate containing sodium diethyl phosphate, the filtrate containing sodium diethyl phosphate is distilled to obtain sodium diethyl phosphate solid and a distillate containing the alcohol solvent, and after the phosphorus content of the distillate meets the standard, it is transferred to a common treatment process, and the sodium diethyl phosphate solid is crushed to obtain a sodium diethyl phosphate product. The purity and recovery rate of the sodium diethyl phosphate product obtained by the recovery method are improved, and the method is simple to operate, less energy consumption, and reduces production costs, and can meet the subsequent deep development and utilization of sodium diethyl phosphate.

[0073] Other embodiments of the present invention will be readily apparent to those skilled in the art after considering the specification and practicing the applications disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art disclosed herein. The specification and examples are to be regarded as exemplary only, and the true scope of the present invention is indicated by the claims.

[0074] It should be understood that the present invention is not limited to the precise structure described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The above-described embodiments of the present invention do not constitute a limitation on the scope of protection of the present invention.

Claims

1. A method for recovering sodium diethyl phosphate from Wittig-Hornal reaction wastewater, characterized in that: The following steps are involved: Adding an acid solution to the Wittig-Hornal reaction wastewater containing sodium diethyl phosphate to obtain an acidic mixed solution, and stirring the acidic mixed solution at a temperature-insulated state; Adding an extractant to the acidic mixed solution, stirring, standing and separating the layers to obtain an aqueous phase containing an inorganic salt and an organic phase containing diethyl phosphate; Adding an alkaline solution to the organic phase containing diethyl phosphate to obtain an alkaline mixed solution, stirring and keeping warm, standing the solution to separate the layers, and separating the layers to obtain an aqueous phase containing sodium diethyl phosphate and an organic phase containing the extractant; adding an alcohol solvent to the aqueous phase containing sodium diethyl phosphate to precipitate an inorganic salt, and filtering to obtain a filtrate containing sodium diethyl phosphate; Distilling the filtrate containing sodium diethyl phosphate to obtain sodium diethyl phosphate solid and a distillate containing the alcohol solvent; The sodium diethyl phosphate solid is crushed to obtain a sodium diethyl phosphate product.

2. The method for recovering sodium diethyl phosphate in the waste water of a Wittig-Hornal reaction according to claim 1, characterized in that: The acid solution is one or more of hydrochloric acid solution, sulfuric acid solution, nitric acid solution and phosphoric acid solution.

3. The method for recovering sodium diethyl phosphate in the waste water of a Wittig-Hornal reaction according to claim 1, characterized in that: The alkaline solution is one or more of a sodium hydroxide solution, a sodium bicarbonate solution and a sodium carbonate solution.

4. The method for recovering sodium diethyl phosphate in the waste water of a Wittig-Horner reaction according to claim 1, characterized in that: The extractant is one or more of dichloroethane, dichloromethane, chloroform, ethyl acetate and toluene.

5. The method for recovering sodium diethyl phosphate from the wastewater of a Wittig-Horner reaction according to claim 1, characterized in that: The alcohol solvent is one or more of a methanol solvent, an ethanol solvent, an isopropanol solvent and a 1,3-butanediol solvent.

6. The method for recovering sodium diethyl phosphate from the wastewater of a Wittig-Horner reaction according to claim 1, characterized in that: The mass ratio of the aqueous phase containing sodium diethyl phosphate to the alcohol solvent is 1:1-4.

7. The method for recovering sodium diethyl phosphate from the wastewater of a Wittig-Horner reaction according to claim 1, characterized in that: The concentration of the acid solution is 20% to 50%, and the pH of the acidic mixed solution is 2 to 3.

8. The method for recovering sodium diethyl phosphate from the wastewater of a Wittig-Horner reaction according to claim 1, characterized in that: The acidic mixed solution is kept warm and stirred for 3 to 4 hours at a temperature of 10 to 80°C.

9. The method for recovering sodium diethyl phosphate from the wastewater of a Wittig-Horner reaction according to claim 1, characterized in that: The stirring time after adding the extractant is 0.5 to 3 hours.

10. The method for recovering sodium diethyl phosphate from waste water of a Wittig-Hornal reaction according to claim 1, characterized in that: The stirring temperature and stirring time of the alkaline mixed solution are 10-80° C. and stirred for 0.5-3 h.

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