Method for separating glycerol and polyethylene glycol and application thereof

Abstract

The invention relates to the technical field of water treatment, and provides a method for separating glycerol and polyethylene glycol and application thereof, and the method comprises the following steps: adding an extraction agent into a mixed system containing glycerol and polyethylene glycol; the extraction agent is selected from chloride of methane or ethyl acetate. According to the invention, glycerin and polyethylene glycol are separated and purified from a mixture of glycerin and polyethylene glycol through a specific extraction agent. Furthermore, glycerol and polyethylene glycol are respectively separated and purified from the epoxy resin industrial wastewater by adopting the separation method, the purity of the polyethylene glycol product can reach 91% or above, and the purity of the glycerol product can reach 95% or above. Furthermore, the polyethylene glycol product separated and recovered from the epoxy resin industrial wastewater can be used for production of epoxy resin through verification, and the quality indexes of the produced epoxy resin, such as epoxy equivalent, total chlorine, hydrolyzed chlorine and the like, are not influenced.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and to a method for separating glycerol and polyethylene glycol and its application. Background Technology

[0002] In the chemical industry, glycerol and polyethylene glycol (PEG) are widely used due to their unique physicochemical properties. Glycerol, also known as glycerol, is a colorless, odorless, and non-toxic viscous liquid; polyethylene glycol (PEG) is an amphiphilic molecule, soluble not only in water but also in a variety of organic solvents. Glycerol and PEG are miscible in any proportion. When glycerol and PEG coexist in a system, traditional separation methods, such as vacuum distillation, activated carbon adsorption, and ion exchange, are often ineffective in separating them. Summary of the Invention

[0003] This invention provides a method for separating glycerol and polyethylene glycol and its application, which solves the problem in the prior art that it is difficult to separate glycerol and polyethylene glycol when they coexist in a system.

[0004] In a first aspect, the present invention provides a method for separating glycerol and polyethylene glycol, comprising: The extractant is added to a mixture containing glycerol and polyethylene glycol; The extractant is selected from chloroform of methane or ethyl acetate.

[0005] Extraction is a separation method that utilizes the difference in solubility or partition coefficient of a substance in two immiscible (or slightly soluble) solvents, allowing the solute to transfer from one solvent to the other. Due to the structural similarity between glycerol and polyethylene glycol (PEG), many solvents, such as mixtures of ethanol and n-hexane, ethanol and cyclohexane, ethanol and petroleum ether, ethanol and toluene, and methanol and toluene, are ineffective in separating glycerol and PEG. However, using the extractant described in this invention—namely, the chlorinated derivative of methane or ethyl acetate—effective separation of the two can be achieved.

[0006] The study found that the phase separation time was longer when using dichloromethane to separate glycerol and PEG than when using ethyl acetate.

[0007] According to the method for separating glycerol and polyethylene glycol provided by the present invention, the chlorinated methane comprises dichloromethane and / or trichloromethane.

[0008] According to the method for separating glycerol and polyethylene glycol provided by the present invention, the content of glycerol in the mixed system containing glycerol and polyethylene glycol is 1% or more.

[0009] According to the method for separating glycerol and polyethylene glycol provided by the present invention, the content of polyethylene glycol in the mixed system containing glycerol and polyethylene glycol is 1% or more.

[0010] According to the method for separating glycerol and polyethylene glycol provided by the present invention, the methanol content in the mixed system containing glycerol and polyethylene glycol is less than 2%.

[0011] According to the method for separating glycerol and polyethylene glycol provided by the present invention, the water content in the mixed system containing glycerol and polyethylene glycol is less than 3%.

[0012] According to the method for separating glycerol and polyethylene glycol provided by the present invention, the salt content in the mixed system containing glycerol and polyethylene glycol is less than 1%.

[0013] According to the method for separating glycerol and polyethylene glycol provided by the present invention, the polyethylene glycol has a molecular weight of 400 or less.

[0014] According to the method for separating glycerol and polyethylene glycol provided by the present invention, the volume ratio of the added extractant to the mixed system is greater than or equal to 2:1.

[0015] In the production of epoxy resin, polyethylene glycol (PEG) can be used as a catalyst. The industrial wastewater generated in this process typically contains water, inorganic salts, glycerol, low-molecular-weight PEG catalyst, and organic polymers. The inorganic salts are primarily industrial sodium chloride, while the organic polymers mainly consist of aged resin, polyglycerol, high-molecular-weight PEG, and polymers of polyols. Currently, the treatment of this type of industrial wastewater mainly involves purifying and separating the industrial salts or glycerol, but the PEG catalyst cannot be recovered.

[0016] Based on this, in a second aspect, the present invention also provides a method for treating epoxy resin production wastewater, comprising: The epoxy resin production wastewater is pretreated to obtain a mixture containing glycerol and polyethylene glycol; Using the method described above for separating glycerol and polyethylene glycol, glycerol and polyethylene glycol in the mixture containing glycerol and polyethylene glycol are separated to obtain glycerol product and polyethylene glycol product.

[0017] In order to make full use of epoxy resin production wastewater, the epoxy resin production wastewater needs to be pretreated as described above before separating glycerol and polyethylene glycol, so as to fully recover the industrial salts therein.

[0018] According to the method for treating epoxy resin production wastewater provided by the present invention, the pretreatment includes neutralization treatment, concentration treatment and desalination treatment in sequence.

[0019] Studies have found that neutralization has a significant impact on desalination. For example, direct extraction of alkaline epoxy resin production wastewater not only results in a longer extraction and phase separation time, but also a lower salt content in the upper phase.

[0020] As an example: Methanol extraction was performed using epoxy resin production wastewater with a salt content of 9%, a water content of 7%, and a pH value greater than 13. The mass ratio of epoxy resin production wastewater to methanol was 1:1, the phase separation time was 5 hours, and the salt content in the resulting upper phase was 0.7%.

[0021] Neutralizing the epoxy resin production wastewater with a salt content of 9%, a water content of 7%, and a pH value greater than 13 yields epoxy resin production wastewater with a salt content of 14%, a water content of 15.6%, and a pH value of 7.5. Extraction is performed under the same conditions as above, and it is found that the phase separation time is 30 min, and the salt content of the upper phase is 0.17%.

[0022] According to the method for treating epoxy resin production wastewater provided by the present invention, the pretreatment includes sequentially performing neutralization treatment, concentration treatment, and desalination treatment; Preferably, the pH value of the epoxy resin production wastewater is adjusted to 6.5~7.5 to obtain a neutralization product; The neutralization product is concentrated to obtain a concentrated product; Methanol was added to the concentrated product for desalting to obtain the mixture containing glycerol and polyethylene glycol.

[0023] According to the method for treating epoxy resin production wastewater provided by the present invention, methanol is added to the concentrated product, and the mixture is allowed to stand to obtain an upper phase and a precipitate. The upper phase is collected and distilled at 75-100°C to obtain the mixture containing glycerol and polyethylene glycol. The salts in the concentrated product are mainly in the precipitate. The methanol and water in the upper phase are mainly in the fraction, and the substrate obtained by distillation is the mixture containing glycerol and polyethylene glycol.

[0024] In this invention, the upper phase is distilled at 75~100°C, and the temperature can be any value or a range of values ​​among 75°C, 80°C, 85°C, 90°C, 95°C and 100°C.

[0025] According to the method for treating epoxy resin production wastewater provided by the present invention, the pH value of the epoxy resin production wastewater is adjusted to 6.5~7.5 to obtain a neutralization product; The neutralization product is concentrated to obtain a concentrated product; Methanol was added to the concentrated product for desalting to obtain the desalted product; The desalted product was distilled at 160~240℃ and -0.095~-0.099MPa, and the fraction was collected to obtain the mixture containing glycerol and polyethylene glycol.

[0026] In this invention, the pH value is adjusted to 6.5~7.5, and the pH value can be any value or a range of values ​​among 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4 and 7.5.

[0027] According to the method for treating epoxy resin production wastewater provided by the present invention, methanol is added to the concentrated product, and the mixture is allowed to stand to obtain an upper phase and a precipitate. The upper phase is collected and distilled at 75-100°C to obtain the desalted product. The salt in the concentrated product is mainly in the precipitate. The methanol and water in the upper phase are mainly in the distilled fraction, and the substrate obtained from the distillation is the desalted product.

[0028] The desalted product is further subjected to the above-mentioned distillation treatment. The resulting mixture containing glycerol and polyethylene glycol has a low molecular weight polyethylene glycol. The polyethylene glycol separated from this mixture can be used for the catalysis of epoxy resins.

[0029] According to the method for treating epoxy resin production wastewater provided by the present invention, the pH adjuster used for pH adjustment is an acid, preferably one or a combination of two or more of hydrochloric acid, phosphoric acid, and glacial acetic acid, with hydrochloric acid being more preferred.

[0030] According to the method for treating epoxy resin production wastewater provided by the present invention, the neutralization product is distilled at 90~120°C to obtain the concentrated product.

[0031] According to the method for treating epoxy resin production wastewater provided by the present invention, the concentration removes water accounting for more than 25% of the neutralization product.

[0032] According to the method for treating epoxy resin production wastewater provided by the present invention, the mass ratio of methanol added to the concentrated product is 1:0.8~1.2.

[0033] In this invention, the mass ratio of the amount of methanol added to the concentrated product is 1:0.8 to 1.2, for example, it can be any value or a range of values ​​among 1:0.8, 1:0.9, 1:1.0, 1:1.1 and 1:1.2.

[0034] According to the method for treating epoxy resin production wastewater provided by the present invention, an extractant is added to the mixture containing glycerol and polyethylene glycol, and the mixture is allowed to stand to separate the first phase and the second phase. In order to more fully separate glycerol and polyethylene glycol, the extractant is preferably added in batches.

[0035] The glycerol is mainly in the first phase; preferably, the first phase is distilled to collect the substrate and obtain the glycerol product; more preferably, the distillation is vacuum distillation, and more preferably, the pressure of vacuum distillation is -0.095 to -0.099 MPa.

[0036] The polyethylene glycol is mainly in the second phase; preferably, the second phase is distilled to collect the substrate and obtain the polyethylene glycol product; more preferably, the distillation is vacuum distillation, and more preferably, the pressure of vacuum distillation is -0.095 to -0.099 MPa.

[0037] Thirdly, the present invention also provides a catalyst for epoxy resin, comprising polyethylene glycol products separated by the method described above.

[0038] The present invention provides a method for separating glycerol and polyethylene glycol and its application, which uses a specific extractant to separate and purify glycerol and polyethylene glycol from a mixture of the two.

[0039] Furthermore, using the above separation method, glycerol and polyethylene glycol are separated and purified from epoxy resin industrial wastewater, with the recovered glycerol having a purity of over 95% and the recovered polyethylene glycol having a purity of over 91%.

[0040] Furthermore, the polyethylene glycol products separated and recovered from epoxy resin industrial wastewater have been verified to be used in the production of epoxy resins, and the quality indicators of the produced epoxy resins, such as epoxy equivalent, total chlorine, and hydrolyzed chlorine, are not affected. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the desalination process in the epoxy resin production wastewater treatment method provided in Example 18 of the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0044] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0045] The polyethylene glycol used in this embodiment of the invention is PEG200 provided by Haian Petrochemical Plant.

[0046] In calculating the yield in this invention, for embodiments involving multiple extractions, the mass of the product is obtained by combining the phases (upper or lower phase) containing the substances miscible with the extractant.

[0047] Example 1 This embodiment provides a method for separating glycerol and polyethylene glycol, the specific process of which is as follows: (1) Preparation: Glycerin and polyethylene glycol are mixed to obtain a mixed system containing glycerin and polyethylene glycol, wherein the mass ratio of glycerin to polyethylene glycol is 8:2.

[0048] (2) Extraction and separation: Dichloromethane, the extractant, is divided into three parts in a ratio of 2:1:1 to extract the mixture in step (1) three times as follows, wherein the total amount of extractant and the mass ratio of the mixture are 2:1.

[0049] (2.1) First extraction: The first part of the extractant is added to the mixture in step (1) to obtain the upper phase and the lower phase. Glycerol is mainly in the upper phase, while polyethylene glycol and extractant are in the lower phase. (2.2) Second extraction: The second part of the extractant is added to the lower phase of step (2.1) to obtain the upper phase and the lower phase. Glycerol is mainly in the upper phase, while polyethylene glycol and the extractant are in the lower phase. (2.3) Third extraction: The third part of the extractant is added to the lower phase of step (2.2) to obtain the upper phase and the lower phase. Glycerol is mainly in the upper phase, while polyethylene glycol and the extractant are in the lower phase.

[0050] The upper and lower phases of the three extractions were sampled separately, the extractant was removed, and after vacuum drying, GC-MS was performed. The purity was calculated using a standard curve based on the detection results. The purity is shown in the table below.

[0051] Table 1 (3) Purify glycerol and recover the extractant: Place all the upper phase from (2) in a rotary evaporator and reduce the pressure to -0.095 to -0.099 MPa. The distillate is the extractant, and the residue is the glycerol product.

[0052] (4) Purify polyethylene glycol and recover the extractant: Place the lower phase in (2.3) in a rotary evaporator and reduce the pressure to -0.095~-0.099MPa. The distillate is the extractant, and the residue is the polyethylene glycol product.

[0053] Example 2 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 1, except that the extractant dichloromethane is divided into three parts in a ratio of 2:1:1 to extract the mixture in step (1) three times. The mass ratio of the total amount of extractant to the mass of the mixture is 3:1.

[0054] The upper and lower phases of the three extractions were sampled separately, the extractant was removed, and after vacuum drying, GC-MS was performed. The purity was calculated using a standard curve based on the detection results. The purity is shown in the table below.

[0055] Table 2 In this embodiment, the yields of the obtained glycerol and PEG products were calculated, and their viscosity and refractive index were tested. The test results are shown in the table below.

[0056] Example 3 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 1, except that the extractant dichloromethane is divided into three parts in a ratio of 2:1:1 to extract the mixture in step (1) three times. The mass ratio of the total amount of extractant to the mass of the mixture is 4:1.

[0057] The upper and lower phases of the three extractions were sampled separately, the extractant was removed, and after vacuum drying, GC-MS was performed. The purity was calculated using a standard curve based on the detection results. The purity is shown in the table below.

[0058] Table 3 The results from Examples 1-3 show that: (1) The total amount of extractant and the mass ratio of the mixed system increased from 2:1 to 4:1. With the increase of extractant amount and the number of extractions, the purity of glycerol in the upper phase was improved.

[0059] (2) The purity of PEG in the lower phase obtained by the second extraction was higher than that obtained by the first extraction, and the purity of PEG in the lower phase obtained by the third extraction was similar to that obtained by the second extraction.

[0060] (3) The purity of PEG is highest when the mass ratio of the total amount of extractant to the mass ratio of the mixed system is 3:1.

[0061] Example 4 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 2, except that the extractant dichloromethane is divided into two parts at a ratio of 1:1 to extract the mixture in step (1) twice. The mass ratio of the total amount of extractant to the mass of the mixture is 3:1.

[0062] In this embodiment, the purity of the obtained glycerol and PEG products was calculated, and their yield, viscosity, and refractive index were tested. The test results are shown in the table below.

[0063] Example 5 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 2, except that the extractant dichloromethane is added at once for extraction, wherein the mass ratio of the total amount of extractant to the mass of the mixed system is 3:1.

[0064] In this embodiment, the purity of the obtained glycerol and PEG products was calculated, and their yield, viscosity, and refractive index were tested. The test results are shown in the table below.

[0065] Table 4 The yield calculation method of this invention is the ratio of the mass of the extracted product to the amount of the corresponding substance fed. Since glycerol and solvent will remain in the PEG product, the yield of PEG will be greater than 100%.

[0066] Example 6 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 3, except that the extractant dichloromethane is divided into two parts at a ratio of 1:1 to extract the mixture in step (1) twice.

[0067] After two extractions, the upper phases from both extractions were combined. Samples were taken from both the lower phase and the combined upper phase, the extractant was removed, and the samples were vacuum dried. GC-MS was then performed, and purity was calculated using a standard curve based on the results. The yield, viscosity, and refractive index were also measured. The test results are shown in the table below.

[0068] Example 7 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 3, except that dichloromethane is added as an extractant for a single extraction.

[0069] The upper and lower phases of the extraction were sampled separately, the extractant was removed, and the samples were dried under vacuum. GC-MS analysis was performed, and purity was calculated using a standard curve based on the results. The yield, viscosity, and refractive index were also measured. The test results are shown in the table below.

[0070] Table 5 As can be seen from Examples 2-7, for a mixture of glycerol and polyethylene glycol with a mass ratio of 8:2, the purity of the glycerol and polyethylene glycol products is similar when the total amount of extractant to the mass ratio of the mixture is 3:1 and 4:1. However, considering the yield, purity, viscosity, and refractive index of each product, when using dichloromethane as the extractant, the preferred mass ratio of the total amount of extractant to the mass ratio of the mixture is 4:1, and the extractant is used for three extractions at a mass ratio of 2:1:1. This can achieve a polyethylene glycol product purity of over 91% and a glycerol product purity of over 95%.

[0071] Example 8 This embodiment provides a method for separating glycerol and polyethylene glycol, the specific process of which is as follows: (1) Material preparation: Same as step (1) in Example 1.

[0072] (2) Extraction and separation: The extractant ethyl acetate is divided into three parts in a ratio of 2:1:1 to extract the mixture in step (1) three times as follows, wherein the total amount of extractant and the mass ratio of the mixture are 2:1.

[0073] (2.1) First extraction: The first part of ethyl acetate was added to the mixture in step (1) to obtain an upper phase and a lower phase. Polyethylene glycol and extractant were in the upper phase, and glycerol was mainly in the lower phase. (2.2) Second extraction: The second portion of ethyl acetate was added to the upper phase from step (2.1), resulting in an upper and lower phase. Polyethylene glycol and the extractant were in the upper phase, while glycerol was mainly in the lower phase. Down Mutually; (2.3) Third extraction: The third portion of ethyl acetate was added to the upper phase of step (2.2), resulting in an upper and lower phase. Polyethylene glycol and the extractant were in the upper phase, while glycerol was mainly in the lower phase. Down Mutually.

[0074] The upper and lower phases of the three extractions were sampled separately, the extractant was removed, and after vacuum drying, GC-MS was performed. The purity was calculated using a standard curve based on the detection results. The purity is shown in the table below.

[0075] Table 6 (3) Purify glycerol and recover the extractant: Place all the lower phases in (2) in a rotary evaporator and reduce the pressure to -0.095 to -0.099 MPa. The distillate is the extractant, and the residue is the glycerol product.

[0076] (4) Purify polyethylene glycol and recover the extractant: Place the upper phase in (2.3) in a rotary evaporator and reduce the pressure to -0.095~-0.099MPa. The extractant is distilled out, and the residue is polyethylene glycol product.

[0077] Example 9 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 8, except that: the extractant ethyl acetate is divided into three parts in a 2:1:1 ratio to extract the mixture in step (1) three times, wherein the mass ratio of the total amount of extractant to the mass of the mixture is 3:1. The upper and lower phases of the three extractions were sampled separately, the extractant was removed, and after vacuum drying, GC-MS was performed. The purity was calculated using a standard curve based on the detection results. The purity is shown in the table below.

[0078] Table 7 In this embodiment, the purity of the obtained glycerol and PEG products was calculated, and their yield, viscosity, and refractive index were tested. The test results are shown in the table below.

[0079] Example 10 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 8, except that: the extractant ethyl acetate is divided into three parts in a ratio of 2:1:1 to extract the mixture in step (1) three times, wherein the mass ratio of the total amount of extractant to the mass ratio of the mixture is 4:1.

[0080] The upper and lower phases of the three extractions were sampled separately, the extractant was removed, and after vacuum drying, GC-MS was performed. The purity was calculated using a standard curve based on the detection results. The purity is shown in the table below.

[0081] Table 8 In this embodiment, the purity of the obtained glycerol and PEG products was calculated, and their yield, viscosity, and refractive index were tested. The test results are shown in the table below.

[0082] Example 11 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 8, except that: the extractant ethyl acetate is divided into three parts in a 2:1:1 ratio to extract the mixture in step (1) three times, wherein the mass ratio of the total amount of extractant to the mass of the mixture is 5:1.

[0083] The upper and lower phases of the three extractions were sampled separately, the extractant was removed, and after vacuum drying, GC-MS was performed. The purity was calculated using a standard curve based on the detection results. The purity is shown in the table below.

[0084] Table 9 As can be seen from Examples 8-11: (1) As the mass ratio of the total extractant to the mixed system increases from 2:1 to 4:1, the purity of PEG in the upper phase gradually increases. When the mass ratio of the total extractant to the mixed system increases to 5:1, the purity of PEG in the upper phase is comparable to that when the mass ratio of the total extractant to the mixed system is 4:1.

[0085] (2) As the mass ratio of the total extractant to the mixed system increases from 2:1 to 4:1, the purity of glycerol in the lower phase gradually increases. When the mass ratio of the total extractant to the mixed system increases to 5:1, the purity of glycerol in the lower phase is comparable to that when the mass ratio of the total extractant to the mixed system is 4:1.

[0086] (3) The purity of PEG in the upper phase is lower in the first extraction than in the second extraction, and similar in the second and third extractions.

[0087] (4) The purity of glycerol in the lower phase increases with the number of extractions.

[0088] Example 12 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 9, except that: the extractant ethyl acetate is divided into two parts at a ratio of 1:1 to extract the mixture in step (1) twice, wherein the mass ratio of the total amount of extractant to the mass ratio of the mixture is 3:1.

[0089] In this embodiment, the purity of the obtained glycerol and PEG products was calculated, and their yield, viscosity, and refractive index were tested. The test results are shown in the table below.

[0090] Example 13 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 9, except that ethyl acetate is added as an extractant for a single extraction, wherein the mass ratio of the total amount of extractant to the mass of the mixed system is 3:1.

[0091] In this embodiment, the purity of the obtained glycerol and PEG products was calculated, and their yield, viscosity, and refractive index were tested. The test results are shown in the table below.

[0092] Table 10 Example 14 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 10, except that: the extractant ethyl acetate is divided into two parts at a ratio of 1:1 to extract the mixture in step (1) twice, wherein the mass ratio of the total amount of extractant to the mass ratio of the mixture is 4:1.

[0093] After two extractions, the upper phases from both extractions were combined. Samples were taken from both the lower phase and the combined upper phase, the extractant was removed, and the samples were vacuum dried. GC-MS was then performed, and purity was calculated using a standard curve based on the results. The yield, viscosity, and refractive index were also measured. The test results are shown in the table below.

[0094] Example 15 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 10, except that ethyl acetate is added as an extractant for a single extraction, wherein the mass ratio of the total amount of extractant to the mass of the mixed system is 4:1.

[0095] The upper and lower phases of the extraction were sampled separately, the extractant was removed, and the samples were dried under vacuum. GC-MS analysis was performed, and purity was calculated using a standard curve based on the results. The yield, viscosity, and refractive index were also measured. The test results are shown in the table below.

[0096] Table 11 As can be seen from Examples 9-15, considering the yield, purity, viscosity, and refractive index of the extracted product, it is preferable to extract more than twice when ethyl acetate is used as the extractant.

[0097] Example 16 This embodiment provides a method for separating glycerol and polyethylene glycol, the specific process of which is as follows: (1) Material preparation: Same as step (1) in Example 1.

[0098] (2) Extraction and separation: The extractant chloroform is divided into two parts at a ratio of 1:1 and the mixture in step (1) is extracted twice as follows, wherein the total amount of extractant and the mass ratio of the mixture are 4:1.

[0099] (2.1) First extraction: The first part of the extractant was added to the mixture in step (1), and the extraction time was 3h to obtain the upper phase and the lower phase. Glycerol was mainly in the upper phase, while polyethylene glycol and extractant were in the lower phase. (2.2) Second extraction: The second part of the extractant was added to the lower phase of step (2.1) and the extraction time was 3h to obtain the upper phase and the lower phase. Glycerol was mainly in the upper phase, while polyethylene glycol and extractant were in the lower phase. (3) Purify glycerol and recover the extractant: Place the upper phase from (2) into a rotary evaporator and reduce the pressure to -0.095 to -0.099 MPa. The distillate is the extractant, and the residue is the glycerol product.

[0100] (4) Purify polyethylene glycol and recover the extractant: Place the lower phase in (2.2) in a rotary evaporator and reduce the pressure to -0.095~-0.099MPa. The extractant is distilled out, and the residue is polyethylene glycol product.

[0101] In this embodiment, the purity of the obtained glycerol and PEG products was calculated, and their yield, viscosity, and refractive index were tested. The test results are shown in the table below.

[0102] Example 17 This embodiment provides a method for separating glycerol and polyethylene glycol. The specific process is basically the same as that in Example 16, except that the extractant chloroform is added at once for extraction, and the extraction time is 4 hours.

[0103] The upper and lower phases of the extraction were sampled separately, the extractant was removed, and the samples were dried under vacuum. GC-MS analysis was performed, and purity was calculated using a standard curve based on the results. The yield, viscosity, and refractive index were also measured. The test results are shown in the table below.

[0104] Table 12 Example 18 This embodiment provides a method for treating epoxy resin production wastewater, the specific process of which is as follows: (1) Neutralization: Take 20 kg of epoxy resin industrial wastewater and neutralize it with 487 g of hydrochloric acid to pH=7.0.

[0105] (2) Concentration: Set up a conventional distillation apparatus, add all the liquids from (1) into the apparatus, and distill off some of the water at atmospheric pressure and 90~120℃ to obtain 16.967 kg of concentrated and dehydrated neutral industrial wastewater.

[0106] (3) Add methanol to remove salt: such as Figure 1As shown, 16.967 kg of methanol was added to 16.967 kg of the above-mentioned neutral industrial wastewater for anti-solvent precipitation and salt separation. Then, the mixture was allowed to stand for 4 hours for phase separation. The lower phase was 1107 g of industrial wet salt, and the upper phase was a high-boiling-point liquid (glycerol + polyethylene glycol) methanol. The upper and lower phases were separated and filtered through a separatory funnel and a Buchner funnel, leaving 32.827 kg of the upper clear liquid.

[0107] (4) Methanol removal: The supernatant from step (3) is put into a conventional distillation apparatus at atmospheric pressure of 75℃~100℃ and cooled with 2℃ condensing water to recover methanol and water, totaling 14.006kg.

[0108] (5) Recovery of glycerol and low molecular weight polyethylene glycol: Based on step (4), the temperature is raised to 160℃~240℃ and the pressure is reduced to -0.095~-0.099MPa to recover 4.27kg of a mixture of glycerol and low molecular weight polyethylene glycol. The residue of distillation is 10.423kg of organic polymer impurities.

[0109] The mixture of glycerol and low molecular weight polyethylene glycol was tested with a salt content of less than or equal to 1%, a methanol content of less than or equal to 2%, a water content of less than or equal to 3%, a glycerol content of 75.58%, a polyethylene glycol content of 18.66%, and a number average molecular weight of polyethylene glycol of less than 400.

[0110] (6) Extraction and separation: In the mixture of glycerol and polyethylene glycol obtained in (5), a total of 17 kg of dichloromethane extractant was added, and the extraction was carried out in three stages to obtain an upper phase and a lower phase. Glycerol was mainly in the upper phase, while polyethylene glycol and extractant were mainly in the lower phase. 3.822 kg of upper phase and 17.320 kg of lower phase were separated. The amount of extractant used in the first extraction was 5.970 kg, and the amount of extractant used in the second extraction was 5.509 kg.

[0111] (7) Purify glycerol and recover the extractant: Place the upper phase from (6) in a rotary evaporator and reduce the pressure to -0.095 to -0.099 MPa. The extractant is distilled out, and the remaining substrate is glycerol product 3.11 kg. The purity of glycerol is 92%.

[0112] (8) Purify polyethylene glycol and recover the extractant: Place the lower phase in (6) in a rotary evaporator and reduce the pressure to -0.095~-0.099MPa. The extractant is distilled out, and the remaining substrate is 0.534kg of polyethylene glycol product with a purity of 91%.

[0113] Example 19 This embodiment provides a method for treating epoxy resin production wastewater, the specific process of which is as follows: (1) A mixture of glycerol and polyethylene glycol was obtained, which was basically the same as that in Example 18, except that the mass of the mixture was 1.057 kg.

[0114] (2) Extraction and separation: A total of 4.221 kg of chloroform extractant was added to the mixture of glycerol and polyethylene glycol, and the extraction was carried out in three stages to obtain an upper phase and a lower phase. Glycerol was mainly in the upper phase, while polyethylene glycol and extractant were mainly in the lower phase. 1.015 kg of the upper phase and 3.794 kg of the lower phase were separated. The amount of extractant used in the first extraction was 1.478 kg, and the amount used in the second extraction was 1.373 kg.

[0115] (3) Purify glycerol and recover the extractant: Place the upper phase from (2) in a rotary evaporator and reduce the pressure to -0.095 to -0.099 MPa. The extractant is distilled out, and the remaining substrate is 0.837 kg of glycerol product with a purity of 95%.

[0116] (4) Purify polyethylene glycol and recover the extractant: Place the lower phase in (2) in a rotary evaporator and reduce the pressure to -0.095~-0.099MPa. The extractant is distilled out, and the remaining substrate is 0.131kg of polyethylene glycol product with a purity of 91%.

[0117] Example 20 This embodiment provides a method for treating epoxy resin production wastewater. The specific process is basically the same as that in Embodiment 19, except for step (2), which is as follows: (2) Extraction and separation: The ethyl acetate extractant was divided into three parts in a ratio of 2:1:1 to extract the glycerol and polyethylene glycol mixture obtained in step (1) three times. Glycerol was mainly in the lower phase, while polyethylene glycol and extractant were mainly in the upper phase. The total amount of extractant and the ratio of glycerol and polyethylene glycol mixture were 400ml:100g.

[0118] The lower phase obtained from each extraction was combined and used to purify glycerol and recover the extractant, yielding the glycerol product. The test results are shown in the table below.

[0119] The above phase was used to purify polyethylene glycol and the extractant was recovered to obtain the polyethylene glycol product. The test results are shown in the table below.

[0120] Table 13 The above experiments show that when ethyl acetate is used as an extractant to recover glycerol and polyethylene glycol from epoxy resin production wastewater, the purity of the polyethylene glycol product can be above 88%, and the purity of the glycerol product can be above 90%.

[0121] Example 21 A method for preparing epoxy resin, the specific process of which is as follows: At room temperature, 400g of bisphenol A, 820g of epichlorohydrin, and the polyethylene glycol product prepared in Example 18 were added sequentially to a three-necked flask. The temperature was raised to 115°C and reacted for 2.5 hours. The mixture was then cooled to 60°C, and under reduced pressure, 200ml of a 48% sodium hydroxide aqueous solution was slowly and uniformly added dropwise. After the addition was completed, the temperature was raised to 130°C, and the epichlorohydrin was recovered under reduced pressure. 300g of toluene was added for dilution, and 120ml of a 10% sodium hydroxide aqueous solution was added dropwise again at 80°C. The mixture was reacted for 1.5 hours, allowed to stand for phase separation, and the lower brine layer was removed. 1g of sodium dihydrogen phosphate was added to the supernatant for neutralization, followed by 600ml of toluene and 300ml of water. The mixture was allowed to stand for phase separation, and the lower brine layer was removed. The temperature was raised to 150°C, and the toluene was recovered under reduced pressure. After the toluene recovery was completed, the mixture was discharged to obtain epoxy resin.

[0122] The performance indicators of the epoxy resin obtained from the test are shown in the table below.

[0123] Comparative Example 1 A method for preparing epoxy resin is basically the same as that in Example 21, except that the polyethylene glycol product obtained in Example 18 is replaced by PEG200 in equal mass.

[0124] The performance indicators of the epoxy resin obtained from the test are shown in the table below.

[0125] Table 14 The test results of Example 21 and Comparative Example 1 show that the experimental process, product yield, and product indicators of using recycled polyethylene glycol products to synthesize epoxy resins are not significantly different from those of using virgin PEG200.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for separating glycerol and polyethylene glycol, characterized by, The method comprises: adding an extractant into a mixed system containing glycerol and polyethylene glycol; the extractant is selected from chlorides of methane or ethyl acetate.

2. The method of claim 1, wherein the glycerol and polyethylene glycol are separated by, the content of glycerol in the mixed system containing glycerol and polyethylene glycol is more than 1%; and / or, the content of polyethylene glycol in the mixed system containing glycerol and polyethylene glycol is more than 1%; and / or, the content of methanol in the mixed system containing glycerol and polyethylene glycol is less than 2%; and / or, the content of water in the mixed system containing glycerol and polyethylene glycol is less than 3%; and / or, the content of salt in the mixed system containing glycerol and polyethylene glycol is less than 1%.

3. The method of separating glycerol and polyethylene glycol according to claim 1 or 2, characterized in that, the chlorides of methane include dichloromethane and / or trichloromethane.

4. The method of separating glycerol and polyethylene glycol according to any one of claims 1 to 3, characterized in that, the volume ratio of the amount of the extractant to the mixed system is greater than or equal to 2:

1.

5. A method for treating epoxy resin production wastewater, characterized by, The method comprises: pre-treating the epoxy resin production wastewater to obtain a mixture containing glycerol and polyethylene glycol; separating glycerol and polyethylene glycol in the mixture containing glycerol and polyethylene glycol by the method of any one of claims 1-4 to obtain a glycerol product and a polyethylene glycol product.

6. The method for treating epoxy resin production wastewater according to claim 5, characterized by, the pre-treatment comprises sequentially performing neutralization treatment, concentration treatment and desalination treatment; preferably, the pH value of the epoxy resin production wastewater is adjusted to 6.5-7.5 to obtain a neutralization product; the neutralization product is subjected to concentration treatment to obtain a concentrated product; methanol is added to the concentrated product to perform desalination treatment to obtain the mixture containing glycerol and polyethylene glycol; further preferably, methanol is added to the concentrated product, and the upper phase and precipitate are obtained by standing, the upper phase is collected, and the mixture containing glycerol and polyethylene glycol is obtained by distillation of the upper phase at 75-100℃.

7. The method for treating epoxy resin production wastewater according to claim 5, characterized by, the pre-treatment comprises sequentially performing neutralization treatment, concentration treatment and desalination treatment; preferably, the pH value of the epoxy resin production wastewater is adjusted to 6.5-7.5 to obtain a neutralization product; the neutralization product is subjected to concentration treatment to obtain a concentrated product; methanol is added to the concentrated product to perform desalination treatment to obtain a desalination product; the desalination product is distilled at 160-240℃ and -0.095--0.099MPa to collect a fraction to obtain the mixture containing glycerol and polyethylene glycol; further preferably, methanol is added to the concentrated product, and the upper phase and precipitate are obtained by standing, the upper phase is collected, and the desalination product is obtained by distillation of the upper phase at 75-100℃.

8. The method for treating epoxy resin production wastewater according to claim 6 or 7, characterized by, the pH value adjusting agent used in the pH value adjustment is an acid; and / or, the neutralization product is distilled at 90-120℃ to obtain the concentrated product; and / or, the concentration removes more than 25% of water in the neutralization product; and / or, the mass ratio of the amount of methanol to the concentrated product is 1:0.8-1.

2.

9. The method for treating the epoxy resin production wastewater according to any one of claims 5 to 8, characterized by, an extractant is added to the mixture containing glycerol and polyethylene glycol, and the first phase and the second phase are separated by standing; preferably, the extractant is added in batches; the glycerol is mainly in the first phase; preferably, the first phase is subjected to distillation, and the glycerol product is obtained by collecting the bottom product; The polyethylene glycol is mainly in the second phase; preferably, the second phase is distilled to collect the polyethylene glycol product as the bottom product.

10. A catalyst for epoxy resin, characterized in that, The polyethylene glycol product isolated by the method of any one of claims 4-9.

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