Extracting agent for thermally induced phase separation method and use method of extracting agent

Abstract

The invention discloses an extracting agent for a thermally induced phase separation method and a use method of the extracting agent, and belongs to the field of organic separation membranes. The invention discloses an extracting agent. The extracting agent comprises solid alcohol and water, the solid alcohol comprises one or more of neopentyl glycol and 2, 5-dimethyl-2, 5 hexanediol; the use method of the extracting agent comprises the following steps: dissolving a membrane material with a diluent to prepare a membrane casting solution, and preparing a membrane; putting the membrane into pure water for quenching operation, and carrying out phase separation; and putting the cured and molded membrane into an extracting agent, soaking, extracting, taking out, and rinsing with water to obtain the required membrane. According to the invention, a novel extracting agent for a thermally induced phase separation method is found, a using method is developed, the prepared membrane has no shrinkage cavity and is good in flux retention, and the used solid alcohol is high in flash point, low in volatility, safe and reliable.

Description

Technical Field

[0001] The invention relates to the field of organic separation membranes, and in particular to an extractant for thermally induced phase separation and a use method thereof. Background Art

[0002] Membrane technology is a process that utilizes the selective separation of membranes to separate, purify, and concentrate different components of a liquid. There is almost no phase change during the separation process, and energy consumption is low. It is a low-energy, low-cost separation technology. The membrane separation device is simple, easy to operate, and easy to manufacture, and can be easily combined with other separation technologies.

[0003] Thermally induced phase separation is a method for preparing separation membranes proposed by Castro in a patent in the early 1980s. The steps for preparing separation membranes by the TIPS method are as follows: first, the polymer, small molecule diluent and other components are formed into a uniform casting liquid at high temperature, the casting liquid is formed into a flat plate, tubular or hollow fiber membrane through a mold, and is placed in a cooling bath for phase separation, the diluent is extracted and removed by the extractant, and finally the extractant is removed to obtain a microporous membrane. Most of the diluents used in the TIPS membrane preparation process are non-water-soluble, and need to be extracted with highly volatile, low boiling point, and low flash point liquid organic reagents, such as methanol, ethanol, acetone, n-hexane, etc. These reagents have high requirements for storage and use, are flammable liquids, and have certain safety hazards. At present, there is no safe and reliable extractant and its use method, and it is urgent to find a safe and reliable extractant and its use method. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides an extractant for thermally induced phase separation and a method for using the same.

[0005] An extractant comprises solid alcohol and water; the solid alcohol comprises any one of neopentyl glycol and 2,5-dimethyl-2,5-hexanediol.

[0006] A method for using an extractant in a thermally induced phase separation method, the method comprising the following steps:

[0007] Using a diluent to dissolve a membrane material to prepare a casting solution for a thermally induced phase separation method, thereby preparing a membrane;

[0008] The membrane is placed in pure water for quenching operation to cause phase separation;

[0009] The solidified membrane is placed in the above-mentioned extractant, soaked, extracted, taken out and rinsed with water.

[0010] Preferably, the content of the solid alcohol is 60-95 wt%.

[0011] Preferably, the extraction temperature is 60-90°C.

[0012] Preferably, the extraction time is 1-10h.

[0013] Preferably, the membrane material includes any one of polypropylene, polyvinylidene fluoride, polyketone and ethylene-chlorotrifluoroethylene copolymer.

[0014] Preferably, the shape of the membrane includes any one of a flat membrane and a hollow fiber membrane.

[0015] Preferably, the diluent includes one or more of a water-soluble diluent and a water-insoluble diluent.

[0016] Preferably, the non-water-soluble diluent includes one or more of dodecanol, tetradecanol, hexadecanol, octadecanoic acid, tetradecanoic acid, palmitic acid, stearic acid, triacetin, tributyl citrate, acetyl tributyl citrate, acetyl triethyl citrate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dibutyl sebacate and sebacic acid.

[0017] Beneficial effects of the present invention:

[0018] 1. Found a thermally induced phase separation extraction agent and developed a corresponding method of use;

[0019] 2. The prepared membrane pores have no shrinkage holes and the flux is well maintained;

[0020] 3. The extractants used are solid alcohol and water. Solid alcohol has a high flash point, low volatility, and is safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 Surface and cross-sectional morphology of the membrane in Example 1;

[0023] Figure 2 Surface and cross-sectional morphology of the membrane in Example 2;

[0024] Figure 3 Surface and cross-sectional morphology of the membrane in Example 3;

[0025] Figure 4 Surface and cross-sectional morphology of the membrane in Example 4;

[0026] Figure 5Surface and cross-sectional morphology of the membrane in Example 5;

[0027] Figure 6 Surface and cross-sectional morphology of the membrane in Example 6;

[0028] Figure 7 Surface and cross-sectional morphology of the membrane in Example 7;

[0029] Figure 8 Surface and cross-sectional morphology of the membrane in Example 8;

[0030] Fig. 9 Surface and cross-sectional morphology of the membrane in Example 9;

[0031] Fig.10 Surface and cross-sectional morphology of the membrane in Example 10;

[0032] Fig.11 Surface and cross-sectional morphology of the membrane in Comparative Example 1;

[0033] Fig.12 Surface and cross-sectional morphology of the membrane in Comparative Example 2;

[0034] Fig.13 Surface and cross-sectional morphology of the membrane in Comparative Example 3;

[0035] Fig.14 These are the surface and cross-sectional morphologies of the membrane in Comparative Example 4. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Specific examples of the present invention are provided below.

[0038] Example 1: 15% polypropylene, 30% octadecyl alcohol and 55% dimethyl isosorbide were used as diluents, stirred at 160°C to obtain a TIPS casting liquid, 30°C pure water was used as a quenching liquid, and then extracted with 60% 2,5-dimethyl-2,5-hexanediol aqueous solution at 80°C for 2h, and then treated with 20% glycerol aqueous solution for 10h, dried at room temperature, and prepared into a flat membrane.

[0039] Example 2: Example 1, other conditions remain unchanged, and extraction is performed with 90% neopentyl glycol at 70°C for 1 h.

[0040] Example 3: 18% polypropylene, 52% dibutyl sebacate and 30% dimethyl isosorbide as diluents, stirred at 160°C to obtain TIPS casting liquid, 30°C pure water was used as quenching liquid, and then extracted with 60% 2,5-dimethyl-2,5-hexanediol aqueous solution at 85°C for 2h, and then treated with 20% glycerol aqueous solution for 10h, dried at room temperature, and prepared into a flat membrane.

[0041] Example 4: Example 3, other conditions remain unchanged, and extraction is performed with 90% neopentyl glycol at 85°C for 1 h.

[0042] Example 5: 20% polyvinylidene fluoride, using 80% acetyl tributyl citrate as a diluent, stirring at 150°C to obtain a TIPS casting liquid, using 45°C pure water as a quenching liquid, then extracting with 80% neopentyl glycol aqueous solution at 85°C for 3h, and then treating with 20% glycerol aqueous solution for 10h, drying at room temperature, and preparing a flat membrane.

[0043] Example 6: Example 5, other conditions remain unchanged, and extraction is performed with 70% 2,5-dimethyl-2,5-hexanediol at 70°C for 4h.

[0044] Example 7: 15% polyketone, using 85% sebacic acid as a diluent, stirring at 160°C to obtain a TIPS casting liquid, using 30°C pure water as a quenching liquid, then extracting with 90% neopentyl glycol aqueous solution at 80°C for 6 hours, and then treating with 20% glycerol aqueous solution for 10 hours, drying at room temperature, and preparing a flat membrane.

[0045] Example 8: Example 7, other conditions remain unchanged, and extraction is performed with 80% 2,5-dimethyl-2,5-hexanediol at 75°C for 3h.

[0046] Example 9: 20% ethylene-chlorotrifluoroethylene copolymer, using 80% tributyl citrate as a diluent, stirring at 200°C to obtain a TIPS casting liquid, using 30°C pure water as a quenching liquid, then extracting with 95% neopentyl glycol aqueous solution at 90°C for 1h, and then treating with 20% glycerol aqueous solution for 10h, and drying at room temperature to prepare a flat membrane.

[0047] Example 10: Example 9, other conditions remain unchanged, and extraction is performed with 75% 2,5-dimethyl-2,5-hexanediol at 70°C for 6h.

[0048] Comparative Example 1: Example 3, other conditions remain unchanged, and extraction is performed with ethanol at 60°C for 2h.

[0049] Comparative Example 2: Example 5, other conditions remain unchanged, and extraction is performed with ethanol at 60°C for 2h.

[0050] Comparative Example 3: Example 7, other conditions remain unchanged, and extraction is performed with ethanol at 60°C for 2h.

[0051] Comparative Example 4: Example 9, other conditions remain unchanged, and extraction is performed with ethanol at 60°C for 2h.

[0052] The average pore sizes of the above embodiments and comparative examples tested by bubble pressure pore size analyzer are listed in Table 1.

[0053] Table 1

[0054] Case Number Average pore size (nm) Example 1 450 Example 2 430 Example 3 165 Example 4 169 Example 5 900 Example 6 960 Example 7 760 Example 8 660 Example 9 62 Example 10 52 Comparative Example 1 175 Comparative Example 2 970 Comparative Example 3 710 Comparative Example 4 52

[0055] The difference between the comparative example and the embodiment lies in the extractant used. The comparative example uses the traditional ethanol extractant. From the morphology and pore size of the membrane, it can be seen that the membrane prepared by using the extractant and extraction method of the present invention has no obvious change and can completely replace the traditional extractant.

[0056] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0057] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. An extractant, characterized in that The extractant includes solid alcohol and water; the solid alcohol includes any one of neopentyl glycol and 2,5-dimethyl-2,5-hexanediol.

2. A method for using an extractant in a thermally induced phase separation method, characterized in that: The method of use comprises the following steps: Using a diluent to dissolve a membrane material to prepare a casting solution for a thermally induced phase separation method, thereby preparing a membrane; The membrane is placed in pure water for quenching operation to cause phase separation; The solidified film is placed in the extractant according to claim 1, soaked, extracted, taken out and rinsed with water.

3. The extractant according to claim 1, characterized in that The content of the solid alcohol is 60-95wt%.

4. The method for using an extractant in a thermally induced phase separation method according to claim 2, characterized in that: The extraction temperature is 60-90°C.

5. The method for using an extractant in a thermally induced phase separation method according to claim 2, characterized in that: The extraction time is 1-10h.

6. The method for using an extractant in a thermally induced phase separation method according to claim 2, characterized in that: The membrane material includes any one of polypropylene, polyvinylidene fluoride, polyketone and ethylene-chlorotrifluoroethylene copolymer.

7. The method for using an extractant in a thermally induced phase separation method according to claim 2, characterized in that: The shape of the membrane includes any one of a flat membrane and a hollow fiber membrane.

8. The method for using an extractant in a thermally induced phase separation method according to claim 2, characterized in that: The diluent includes one or more of a water-soluble diluent and a water-insoluble diluent.

9. The method for using an extractant in a thermally induced phase separation method according to claim 8, characterized in that: The non-water-soluble diluent includes one or more of dodecanol, tetradecanol, hexadecanol, octadecanoic acid, tetradecanol, palmitic acid, stearic acid, triacetin, tributyl citrate, acetyl tributyl citrate, acetyl triethyl citrate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dibutyl sebacate and sebacic acid.

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