Monovalent cation selective separation membrane and preparation method thereof

Abstract

The invention discloses a monovalent cation selective separation membrane and a preparation method thereof, and belongs to the technical field of ion exchange membranes. The preparation method comprises the following steps: respectively dissolving a diamine monomer and an acyl chloride monomer in water and n-hexane to respectively obtain a water-phase solution and an oil-phase solution; fixing the porous base membrane in the middle of a central channel of a diffusion device, respectively pouring the water-phase solution and the oil-phase solution into diffusion chambers on the upper side and the lower side of the central channel, carrying out diffusion interface polymerization, taking out the membrane, washing with n-hexane, and drying to obtain the monovalent cation selective separation membrane. The preparation method of the monovalent cation selective separation membrane provided by the invention has the advantages of cheap raw materials, mild preparation conditions, simple operation and the like, so that the membrane preparation cost can be greatly reduced, and the existence of chloromethyl on the membrane makes the polyamide structure more stable. Meanwhile, the electrodialysis Na < + > / Me4N < + > and K < + > / Me4N < + > separation of the prepared monovalent cation selective separation membrane shows performance superior to that of a commercial CIMS membrane, and the monovalent cation selective separation membrane has wide application prospects in the fields of electronic-grade TMAH purification preparation and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of ion exchange membranes, and in particular relates to a monovalent cation selective separation membrane and a preparation method thereof. Background Art

[0002] Electronic grade TMAH is widely used in the field of electronic chemicals, but its preparation inevitably introduces Na + , K + , which greatly affects the service life of electronic products, so it is necessary to purify the prepared TMAH. TMAH purification is essentially the purification of Me 4 N + with Na + , K + For separation, the electrodialysis technology with monovalent cation selective separation membrane as the core has the potential for large-scale application in the field of TMAH purification due to its advantages such as no pollution and high separation efficiency.

[0003] At present, monovalent cation selective separation membranes are mainly prepared by interfacial polymerization, which is a polymerization reaction carried out at the interface of two immiscible solutions and has many advantages. First, the diamine monomers and acyl chloride monomers can be purchased directly, and they are cheap and easy to operate. They only need to be configured into reaction solutions and the solutions are placed on the membrane one after another; secondly, the generated polyamide has a dense network structure and has strong hydrophilicity, which can give the membrane better ion selectivity and permeation flux. Traditional interfacial polymerization is carried out by immersion operation, which will lead to problems such as difficulty in controlling the interfacial polymerization reaction speed and uneven thickness of the polyamide layer. Therefore, the use of diffusion interfacial polymerization to prepare monovalent cation selective separation membranes has broad development prospects in the field of TMAH purification.

[0004] CN202310856256.1 discloses a method for preparing a nanofiltration membrane under interfacial polymerization regulated by an azide-type ion additive. The method adds a porous substrate membrane to an aqueous solution of an azide-type ion organic molecule amine and immerses it at room temperature. The impregnated porous substrate membrane is added to an oil phase of aromatic acyl chloride, and a separation cortex is formed through an interfacial polymerization process under ultraviolet light. At the same time, the interfacial polymerization regulation of the impregnation and the ionization modification of the polyamide network are achieved to construct a high-performance composite nanofiltration membrane.

[0005] However, the existing interfacial polymerization modification methods represented by the above methods use an immersion interfacial polymerization method, which results in uneven thickness of the polyamide selective layer grown on a porous substrate and insufficient density of the polyamide structure, making it difficult to improve the ion separation performance of the membrane. Summary of the invention

[0006] The object of the present invention is to provide a monovalent cation selective separation membrane and a preparation method thereof, which has low raw materials, mild preparation conditions, and uniform and easily controllable polyamide thickness. + / Me 4 N + , K + / Me 4 N + The separation performance is superior to that of commercial CIMS membranes and has broad application prospects in the fields of electronic-grade TMAH purification and preparation.

[0007] To achieve the above object, the present invention adopts the following technical solution: A method for preparing a monovalent cation selective separation membrane comprises the following steps: dissolving a diamine monomer in water to obtain an aqueous solution, and dissolving an acyl chloride monomer in n-hexane to obtain an oil solution; performing diffusion interface polymerization on the surface of a porous base membrane with the aqueous solution and the oil solution to obtain a monovalent cation selective separation membrane; Wherein, the diamine monomer is selected from piperazine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine; Wherein, the porous substrate contains chloromethyl groups that can react with diamine monomers; Furthermore, the porous substrate also contains sulfonic acid groups that can enhance ion flux; Furthermore, the porous base membrane is a base membrane blended with chloromethylated polyethersulfone and sulfonated polyethersulfone; Wherein, the concentration of the diamine monomer in the aqueous phase solution is 0.2-1.0 wt / v%, and the concentration of the acyl chloride monomer in the oil phase solution is 0.01 wt / v%; The diffusion interface polymerization is carried out using an H-type diffusion device, which is composed of a central channel and diffusion chambers located on the upper and lower sides of the central channel; a porous base membrane is fixed in the middle of the central channel of the diffusion device, an oil phase solution is poured into the diffusion chamber located on the upper side of the central channel, and a water phase solution is poured into the diffusion chamber located on the lower side of the central channel, and a diffusion interface polymerization reaction is carried out; Furthermore, the diffusion interface polymerization reaction is carried out for 20-120 minutes at a temperature of 10-40°C.

[0008] A monovalent cation selective separation membrane prepared by the above preparation method.

[0009] The above-mentioned monovalent cation selective separation membrane is used in the selective separation of monovalent cations and the purification and preparation of electronic grade TMAH.

[0010] The beneficial effects of the present invention are: (1) The diffusion interfacial polymerization method of the present invention for preparing a monovalent cation selective separation membrane can not only directionally grow a polyamide selective layer on the membrane surface, but also has a simple preparation process and is easy to control the degree of reaction, which is conducive to the growth of a uniform, dense and defect-free polyamide selective layer.

[0011] (2) Compared with the existing monovalent cation selective separation membranes, the monovalent cation selective separation membrane prepared by the present invention uses a porous membrane substrate with chloromethyl groups, which can undergo a substitution reaction with the diamine monomer, so that there is an interaction force between the membrane substrate and the polyamide selective layer, and the prepared membrane structure is more stable. In addition, the membrane substrate also contains sulfonic acid groups, which can increase the ion flux of the membrane and further improve the monovalent cation separation performance of the membrane.

[0012] (3) The diffusion interfacial polymerization method adopted in the present invention is universally applicable to different diamine monomers, and different diamine monomers can be used according to needs to prepare monovalent cation selective separation membranes with different performances. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The infrared spectra of the upper surface (a) and the lower surface (b) of the monovalent cation selective separation membrane prepared in Example 1-5.

[0014] Figure 2 Full spectrum scanning XPS spectra of the upper surface (a) and lower surface (b) of the monovalent cation selective separation membrane prepared in Example 1-5.

[0015] Figure 3 These are SEM images of the upper surface, lower surface, and cross section of the monovalent cation selective separation membrane prepared in Examples 1-5.

[0016] Figure 4 The water contact angles of the upper surface (a) and the lower surface (b) of the monovalent cation selective separation membrane prepared in Example 1-5.

[0017] Figure 5 is the Na on the upper surface (a) and lower surface (b) of the monovalent cation selective separation membrane prepared in Example 1-5 + / Me 4 N + , K + / Me 4 N + Separation performance diagram. DETAILED DESCRIPTION

[0018] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0019] The chemical reagents used in the embodiments of the present invention are all commercially available.

[0020] The chloromethylated polyethersulfone and sulfonated polyethersulfone blended base membrane (C / S-PES) used in the embodiment of the present invention is prepared by a non-solvent phase inversion method, and the specific steps are: weigh equal masses of chloromethylated polyethersulfone (CMPES) (the preparation of CMPES has been disclosed in: Journal of Membrane Science, 2023, 673: 121499.) and sulfonated polyethersulfone (SPES) (the preparation of SPES has been disclosed in: Journal of Membrane Science, 2024, 706: 122951. Specifically HBS-PES-1.0 polymer), dissolve with NMP, stir at room temperature for 24 hours to fully dissolve it, and filter with a non-woven fabric to remove impurities therein. Then the filtrate is ultrasonicated at room temperature for 10 minutes and then left to stand overnight to remove bubbles in the filtrate to obtain a uniform and clear 25wt% casting solution. Pour the casting liquid evenly on the glass plate (in the form of long strips), use a scraping knife to scrape the casting liquid on the glass plate at a uniform and stable speed, control the thickness of the scraped casting liquid to be 200 μm, and then immerse the glass plate vertically in a large bucket of ultrapure water, and let it stand at room temperature until the film naturally falls off the glass plate. Finally, take out the membrane and place it in ultrapure water, and change the ultrapure water several times to completely remove the NMP therein, and obtain a C / S-PES base membrane.

[0021] The diffusion device used for the diffusion interfacial polymerization reaction in the embodiment of the present invention is H-shaped, consisting of a central channel and diffusion chambers located on the upper and lower sides of the central channel. The inner diameter of the central channel is 4.4 cm and the outer diameter is 6.4 cm. The volume of the upper and lower diffusion chambers is 30 mL.

[0022] Embodiment 1: Piperazine (PIP) was dissolved in deionized water to make the concentration of PIP 0.2wt / v% to obtain a PIP aqueous solution; trimesoyl chloride (TMC) was dissolved in n-hexane to make the concentration of TMC 0.01wt / v% to obtain a TMC n-hexane solution. The C / S-PES base membrane was cut into a size of 5cm×5cm and fixed in the middle of the central channel of the diffusion device, 30mL of TMC n-hexane solution was poured into the diffusion chamber located on the upper side of the central channel, and 30mL of PIP aqueous solution was poured into the diffusion chamber located on the lower side of the central channel at the same time, and the diffusion interface polymerization reaction was carried out at room temperature for 60min. After the reaction was completed, the membrane was taken out, and the excess reaction liquid on the membrane surface was rinsed off with n-hexane, and then the membrane was placed in a 60℃ oven for drying for 30min to obtain a monovalent selective cation separation membrane (C / S-PES-0.2PIP). The water contact angle of the upper surface of the prepared monovalent selective cation separation membrane was measured to be 44.4°, the water contact angle of the lower surface was 85.3°, the O / N value of XPS on the upper surface of the membrane was 1.83, the O / N value of XPS on the lower surface of the membrane was 15.33, and the thickness of the polyamide selective layer was 302nm.

[0023] The monovalent selective cation separation membrane prepared in Example 1 was used to perform an electrodialysis experiment at 25°C. 100 ml of deionized water and 100 ml of 0.1 M NaCl (or KCl) / MeOH were added to the concentration chamber and the desalination chamber, respectively. 4 NHCO 3 Mixed salt solution circulation, the polar chamber supplement solution is 100ml of 0.3M Na 2 SO 4 , circulation flow rate is 40ml·min -1 , the effective membrane area of ​​the device is 2cm 2 The operating current is constant at 0.004A (i.e. 2mA cm -2 ). The Na of the prepared monovalent selective cation separation membrane was measured. + The flux is 0.926 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 9.89, K + The flux is 0.961 mol m -2 h -1 , K + / Me 4 N + The selectivity is 15.36, which is comparable to commercial membranes (CIMS, Na + The flux is 0.556 mol m -2 h -1 , Na + / Me4 N + The selectivity is 18.42, K + The flux is 0.570 mol m -2 h -1 , K + / Me 4 N + The selectivity is 19.38) compared with Na + / Me 4 N + While the selectivity is similar, Na + The flux is higher.

[0024] Embodiment 2: A monovalent cation selective separation membrane was prepared by a method similar to that of Example 1, except that the concentration of PIP in the PIP aqueous solution was changed to 0.4 wt / v%. The water contact angle of the upper surface of the prepared monovalent selective cation separation membrane (C / S-PES-0.4PIP) was 42.8°, the water contact angle of the lower surface was 80.9°, the O / N value of XPS of the upper surface of the membrane was 1.34, the O / N value of XPS of the lower surface of the membrane was 14.46, the thickness of the polyamide selective layer was 418 nm, and the electrodialysis Na + The flux is 0.781 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 23.69, K + The flux is 0.774 mol m -2 h -1 , K + / Me 4 N + The selectivity is 23.03.

[0025] Embodiment 3: A monovalent cation selective separation membrane was prepared by a method similar to that of Example 1, except that the concentration of PIP in the PIP aqueous solution was changed to 0.6 wt / v%. The water contact angle of the upper surface of the prepared monovalent selective cation separation membrane (C / S-PES-0.6PIP) was 42.2°, the water contact angle of the lower surface was 81.1°, the O / N value of XPS of the upper surface of the membrane was 1.09, the O / N value of XPS of the lower surface of the membrane was 13.21, the thickness of the polyamide selective layer was 524 nm, and the electrodialysis Na + The flux is 0.585 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 33.38, K +The flux is 0.602 mol m -2 h -1 , K + / Me 4 N + The selectivity is 35.82.

[0026] Embodiment 4: A monovalent cation selective separation membrane was prepared by a method similar to that of Example 1, except that the concentration of PIP in the PIP aqueous solution was changed to 0.8 wt / v%. The water contact angle of the upper surface of the prepared monovalent selective cation separation membrane (C / S-PES-0.8PIP) was 36.4°, the water contact angle of the lower surface was 85.0°, the O / N value of XPS of the upper surface of the membrane was 1.35, the O / N value of XPS of the lower surface of the membrane was 4.92, the thickness of the polyamide selective layer was 699 nm, and the electrodialysis Na + The flux is 0.471 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 28.12, K + The flux is 0.516 mol m -2 h -1 , K + / Me 4 N + The selectivity is 31.85.

[0027] Embodiment 5: A monovalent cation selective separation membrane was prepared by a method similar to that of Example 1, except that the concentration of PIP in the PIP aqueous solution was changed to 1.0 wt / v%. The water contact angle of the upper surface of the prepared monovalent selective cation separation membrane (C / S-PES-1.0PIP) was 34.8°, the water contact angle of the lower surface was 84.5°, the O / N value of XPS of the upper surface of the membrane was 1.19, the O / N value of XPS of the lower surface of the membrane was 15.15, the thickness of the polyamide selective layer was 841 nm, and the electrodialysis Na + The flux is 0.347 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 26.09, K + The flux is 0.370 mol m -2 h -1 , K + / Me 4 N + The selectivity is 25.14.

[0028] Based on Examples 1-5, diffusion interfacial polymerization can directionally grow a polyamide selective layer on the membrane surface, and the preparation requirements are met when the PIP concentration is 0.6wt / v%, and its performance is optimal. Further increasing the PIP concentration will affect the density and ion selectivity of the polyamide structure.

[0029] Figure 1 The infrared spectra of the upper and lower surfaces of the C / S-PES base membrane and the C / S-PES-XPIP series modified membrane (i.e., the monovalent selective cation separation membrane of Examples 1-5) are shown in FIG. -1 and 1072cm -1 The peak at is attributed to -SO 3 - Compared with C / S-PES base membrane, C / S-PES-XPIP series modified membrane has a characteristic peak at 1368cm -1 The new peak at 1441 cm-1 is the peak of the tertiary amine on the amide group. -1 The new peak at 1618 cm is attributed to the bending vibration peak of the methylene group on the PIP ring. -1 The new peaks at 756 cm-1 are the stretching vibration peaks of C=O on the amide group. The appearance of these new peaks indicates that the polyamide selective layer can be grown on the surface of the C / S-PES membrane by diffusion interfacial polymerization. -1 The peak at is attributed to the peak of chloromethyl on CMPES. Compared with the C / S-PES base membrane, the peak intensity of the C / S-PES-XPIP series modified membrane at this position is weakened, which indicates that the chloromethyl on CMPES reacts with PIP, thereby achieving an interaction force between the membrane substrate and the polyamide selective layer, making its structure more stable. In contrast, the characteristic peaks of amide groups and PIP rings were not observed at the corresponding position on the lower surface of the membrane, indicating that the diffusion interface polymerization will not grow a polyamide selective layer on the lower surface of C / S-PES, that is, the diffusion interface polymerization method can be used to directionally grow a polyamide selective layer on the upper surface of the C / S-PES porous base membrane.

[0030] Figure 2It is the full spectrum scanning XPS spectra of the upper and lower surfaces of the C / S-PES base membrane and the C / S-PES-XPIP series modified membrane (i.e., the monovalent selective cation separation membrane of Examples 1-5), wherein the characteristic peaks at 284.80 eV and 531.88 eV belong to C1s and O1s, respectively. After the diffuse interface polymerization, compared with the C / S-PES base membrane, the characteristic peak of the C / S-PES-XPIP series modified membrane at the 399.98 eV position is significantly enhanced, which is attributed to N1s, which is consistent with its FT-IR results, further indicating that the diffuse interface polymerization introduces a polyamide selective layer on the upper surface of the membrane. In addition, the characteristic peak at 199.8eV is attributed to Cl2p. It is worth noting that compared with the C / S-PES-based membrane, the Cl2p peak is almost unobservable in the C / S-PES-XPIP series modified membranes. There are two reasons for this: First, the chloromethyl groups on the C / S-PES-based membrane react with PIP to consume part of the Cl; second, the polyamide selective layer grown on the membrane surface covers the chloromethyl groups, resulting in the undetectable Cl peak, which is consistent with the FT-IR results, proving that there is a chemical bond connection between the membrane substrate and the polyamide selective layer, and its structure is expected to be more stable. In addition, the peak at 167.7eV is attributed to S2p, which comes from the -SO3- on the C / S-PES main chain and side chain. After the diffusion interface polymerization, a polyamide selective layer grows on the C / S-PES surface, so the S2p peak is unobservable in the C / S-PES-XPIP series modified membranes, which is also consistent with expectations. In contrast, the elemental composition of the lower surface of the membrane did not change significantly, indicating that diffuse interfacial polymerization would not grow a polyamide selective layer on the lower surface of C / S-PES, which is consistent with the FTIR results.

[0031] Figure 3The upper surface, lower surface, and cross-sectional view of the C / S-PES base membrane and the C / S-PES-XPIP series modified membrane (i.e., the monovalent selective cation separation membrane of Examples 1-5). As for the upper surface, the morphology of the C / S-PES base membrane is relatively smooth and flat, and many granular substances are generated on the upper surface of the C / S-PES-XPIP series modified membranes, which are polyamide particles. The presence of the polyamide layer makes the surface rougher. And with the increase of PIP concentration, the size of polyamide particles also increases slightly. When the PIP concentration is 0.6wt / v%, the distribution of polyamide particles is the most uniform. When the PIP concentration is further increased, the polyamide particles aggregate, resulting in uneven distribution, which is also consistent with the XPS results. This shows that too small or too large a PIP concentration will affect the density of the growing polyamide. As for the lower surface, the morphology of the C / S-PES-based membrane and the C / S-PES-XPIP series modified membrane is very similar, and both have many obvious pore structures. This is due to the use of non-solvent-induced phase transformation to prepare the porous base membrane. The existence of these pore structures is conducive to the efficient transport of ions. However, no polyamide particles were observed on the lower surface of the C / S-PES-XPIP series modified membrane as on the upper surface, which also shows that the diffusion interface polymerization only directional growth of the polyamide selection layer on the upper surface of the C / S-PES membrane substrate, which is consistent with the FT-IR and XPS data results. For the cross section, the top structure of the C / S-PES-based membrane cross section is uniform and smooth, and no modified layer structure is observed, while the top of the cross section of the C / S-PES-XPIP series modified membrane has an additional layer of modified structure, which is the polyamide selection layer grown on the upper surface of the membrane through diffusion interface polymerization. As the PIP concentration increases, the thickness of the polyamide selection layer also increases, and this trend is consistent with expectations. At the same time, in the cross-sectional view of the C / S-PES-XPIP series modified membranes, the membrane substrate and the polyamide selective layer fit tightly together, and no shedding was found. This is the same as the expected result. The presence of chloromethyl can react with PIP, thereby providing an interaction force between the membrane substrate and the polyamide selective layer.

[0032] Embodiment 6: The monovalent cation selective separation membrane was prepared by a method similar to that of Example 3, except that the diffusion interface polymerization reaction time was changed to 20 min. The water contact angle of the upper surface of the prepared monovalent cation selective separation membrane was measured to be 51.8°, the O / N value of XPS was 1.13, the thickness of the polyamide selective layer was 266 nm, and the electrodialysis Na + The flux is 0.712 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 17.66, K + The flux is 0.782 mol m-2 h -1 , K + / Me 4 N + The selectivity is 21.85.

[0033] Embodiment 7: The monovalent cation selective separation membrane was prepared by a method similar to that of Example 3, except that the diffusion interface polymerization reaction time was changed to 40 min. The water contact angle of the upper surface of the prepared monovalent cation selective separation membrane was measured to be 46.5°, the O / N value of XPS was 1.12, the thickness of the polyamide selective layer was 351 nm, and the electrodialysis Na + The flux is 0.667 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 26.59, K + The flux is 0.650 mol m -2 h -1 , K + / Me 4 N + The selectivity is 31.24.

[0034] Embodiment 8: The monovalent cation selective separation membrane was prepared by a method similar to that of Example 3, except that the diffusion interface polymerization reaction time was changed to 80 min. The water contact angle of the upper surface of the prepared monovalent cation selective separation membrane was measured to be 41.4°, the O / N value of XPS was 1.09, the thickness of the polyamide selective layer was 601 nm, and the electrodialysis Na + The flux is 0.521 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 41.47, K + The flux is 0.546 mol m -2 h -1 , K + / Me 4 N + The selectivity is 44.11.

[0035] Embodiment 9: The monovalent cation selective separation membrane was prepared by a method similar to that of Example 3, except that the diffusion interface polymerization reaction time was changed to 100 min. The water contact angle of the upper surface of the prepared monovalent cation selective separation membrane was measured to be 37.4°, the O / N value of XPS was 1.18, the thickness of the polyamide selective layer was 737 nm, and the electrodialysis Na+ The flux is 0.473 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 36.52, K + The flux is 0.480 mol m -2 h -1 , K + / Me 4 N + The selectivity is 38.37.

[0036] Embodiment 10: The monovalent cation selective separation membrane was prepared by a method similar to that in the example, except that the diffusion interface polymerization reaction time was changed to 20 min. The water contact angle of the upper surface of the prepared monovalent cation selective separation membrane was measured to be 36.9°, the O / N value of XPS was 1.35, the thickness of the polyamide selective layer was 1.04 μm, and the electrodialysis Na + The flux is 0.415 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 34.12, K + The flux is 0.409 mol m -2 h -1 , K + / Me 4 N + The selectivity is 35.14.

[0037] Based on Examples 6-10, it is not difficult to find that the O / N value of the monovalent selective cation separation membrane prepared by the diffusion interface polymerization time is too short is high, the polyamide structure is not dense enough, and the separation performance of the membrane is relatively poor. The thickness of the polyamide selective layer of the monovalent selective cation separation membrane prepared by the diffusion interface polymerization time is too thick, and the Na + , K + The flux was too low, so the optimal diffusion interfacial polymerization time was 80 min.

[0038] Embodiment 11: A monovalent cation selective separation membrane was prepared by a method similar to that of Example 3, except that the diamine monomer PIP was replaced with ethylenediamine. The water contact angle of the upper surface of the prepared monovalent cation selective separation membrane was measured to be 37.4°, the O / N value of XPS was 1.27, the thickness of the polyamide selective layer was 564 nm, and the electrodialysis Na + The flux is 0.612 mol m -2 h -1 , Na + / Me4 N + The selectivity is 36.41, K + The flux is 0.609 mol m -2 h -1 , K + / Me 4 N + The selectivity is 39.61.

[0039] Embodiment 12: A monovalent cation selective separation membrane was prepared by a method similar to that of Example 3, except that the diamine monomer PIP was replaced with diethylenetriamine. The water contact angle of the upper surface of the prepared monovalent cation selective separation membrane was measured to be 44.9°, the O / N value of XPS was 1.33, the thickness of the polyamide selective layer was 475 nm, and the electrodialysis Na + The flux is 0.659 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 26.34, K + The flux is 0.669 mol m -2 h -1 , K + / Me 4 N + The selectivity is 28.52.

[0040] Embodiment 13: A monovalent cation selective separation membrane was prepared by a method similar to that of Example 3, except that the diamine monomer PIP was replaced with triethylenetetramine. The water contact angle of the upper surface of the prepared monovalent cation selective separation membrane was measured to be 49.0°, the O / N value of XPS was 1.36, the thickness of the polyamide selective layer was 341 nm, and the electrodialysis Na + The flux is 0.662 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 19.26, K + The flux is 0.685 mol m -2 h -1 , K + / Me 4 N + The selectivity is 25.64.

[0041] Embodiment 14: A monovalent cation selective separation membrane was prepared by a method similar to that of Example 3, except that the diamine monomer PIP was replaced with tetraethylenepentamine. The water contact angle of the upper surface of the prepared monovalent cation selective separation membrane was measured to be 66.0°, the O / N value of XPS was 1.47, the thickness of the polyamide selective layer was 287 nm, and the electrodialysis Na + The flux is 0.688 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 18.65, K + The flux is 0.694 mol m -2 h -1 , K + / Me 4 N + The selectivity is 17.83.

[0042] Embodiment 15: A monovalent cation selective separation membrane was prepared by a method similar to that of Example 3, except that the diamine monomer PIP was replaced with pentaethylenehexamine. The water contact angle of the upper surface of the prepared monovalent cation selective separation membrane was measured to be 69.7°, the O / N value of XPS was 1.52, the thickness of the polyamide selective layer was 159 nm, and the electrodialysis Na + The flux is 0.724 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 11.90, K + The flux is 0.717 mol m -2 h -1 , K + / Me 4 N + The selectivity is 14.23.

[0043] It is not difficult to find from Examples 11 to 15 that the diffusion interfacial polymerization method has a certain effect on different fatty chain diamines. However, as the molecular chain length of the diamine monomer increases, the structure of the polyamide selective layer of the prepared monovalent selective cation separation membrane becomes less dense and the thickness is too thin, and the Na + / Me 4 N + , K + / Me 4 N + The selectivity is also worse.

[0044] Embodiment 16: A monovalent cation selective separation membrane was prepared by a method similar to that of Example 3, except that the diamine monomer PIP was replaced with o-phenylenediamine. The water contact angle of the upper surface of the prepared monovalent cation selective separation membrane was measured to be 71.2°, the O / N value of XPS was 1.41, the thickness of the polyamide selective layer was 861 nm, and the electrodialysis Na + The flux is 0.547 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 11.07, K + The flux is 0.534 mol m -2 h -1 , K + / Me 4 N + The selectivity is 9.86.

[0045] Embodiment 17: A monovalent cation selective separation membrane was prepared by a method similar to that of Example 3, except that the diamine monomer PIP was replaced with m-phenylenediamine. The water contact angle of the upper surface of the prepared monovalent cation selective separation membrane was measured to be 75.5°, the O / N value of XPS was 1.34, the thickness of the polyamide selective layer was 615 nm, and the electrodialysis Na + The flux is 0.431 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 25.49, K + The flux is 0.437 mol m -2 h -1 , K + / Me 4 N + The selectivity is 29.43.

[0046] Embodiment 18: A monovalent cation selective separation membrane was prepared by a method similar to that of Example 3, except that the diamine monomer PIP was replaced with p-phenylenediamine. The water contact angle of the upper surface of the prepared monovalent cation selective separation membrane was measured to be 78.3°, the O / N value of XPS was 1.35, the thickness of the polyamide selective layer was 737 nm, and the electrodialysis Na + The flux is 0.465 mol m -2 h -1 , Na + / Me 4 N + The selectivity is 20.26, K + The flux is 0.441 mol m-2 h -1 , K + / Me 4 N + The selectivity is 25.78.

[0047] It is not difficult to find from Examples 16-18 that the diffusion interfacial polymerization method has a certain effect on different phenylenediamines, among which m-phenylenediamine has a similar effect to p-phenylenediamine and has a good Na + / Me 4 N + , K + / Me 4 N + The selectivity of o-phenylenediamine is the worst. This is because the two primary amine groups are too close to each other, which has a strong steric hindrance and affects the interfacial polymerization reaction. + / Me 4 N + , K + / Me 4 N + The selectivity is also the worst.

[0048] The results of the above examples show that the optimal diamine monomer solution concentration for preparing the monovalent cation selective separation membrane by the diffusion interfacial polymerization method adopted by the present invention is 0.4wt / v%, the optimal diffusion interfacial polymerization reaction time is 60min, and the optimal diamine monomer is piperazine. Compared with the traditional immersion interfacial polymerization, the diffusion interfacial polymerization has the characteristics of more controllable reaction process and more uniform and dense polyamide selective layer. At the same time, the C / S-PES substrate used can undergo substitution reaction with the diamine monomer due to the presence of chloromethyl, introducing the interaction force between the membrane substrate and the polyamide selective layer, making the prepared monovalent cation selective separation membrane more stable. Therefore, this method has broad development prospects.

[0049] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing a monovalent cation selective separation membrane, characterized in that: The diamine monomer is dissolved in water to obtain an aqueous solution, and the acyl chloride monomer is dissolved in n-hexane to obtain an oil solution; the aqueous solution and the oil solution are subjected to oil-water diffusion interface polymerization on the surface of a porous base membrane to obtain a monovalent cation selective separation membrane.

2. The preparation method according to claim 1, characterized in that: The diamine monomer is any one of piperazine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, o-phenylenediamine, m-phenylenediamine and p-phenylenediamine.

3. The preparation method according to claim 1, characterized in that: The porous base film contains chloromethyl groups that can react with the diamine monomer.

4. The preparation method according to claim 3, characterized in that: The porous base membrane contains sulfonic acid groups which can enhance ion flux.

5. The preparation method according to claim 4, characterized in that: The porous base membrane is a blended base membrane of chloromethylated polyether sulfone and sulfonated polyether sulfone.

6. The preparation method according to claim 1, characterized in that: The concentration of the diamine monomer in the aqueous phase solution is 0.2-1.0 wt / v%, and the concentration of the acyl chloride monomer in the oil phase solution is 0.01 wt / v%.

7. The preparation method according to claim 1, characterized in that: The diffusion interface polymerization is carried out using an H-type diffusion device, which is composed of a central channel and diffusion chambers located on the upper and lower sides of the central channel; a porous base membrane is fixed in the middle of the central channel of the diffusion device, an oil phase solution is poured into the diffusion chamber located on the upper side of the central channel, and a water phase solution is poured into the diffusion chamber located on the lower side of the central channel, to carry out a diffusion interface polymerization reaction.

8. The preparation method according to claim 7, characterized in that: The diffusion interface polymerization reaction takes 20-120 minutes and the temperature is 10-40°C.

9. A monovalent cation selective separation membrane prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the monovalent cation selective separation membrane as claimed in claim 9 in the selective separation of monovalent cations and the purification and preparation of electronic grade TMAH.

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