Composite film preparation device based on interfacial polymerization and ultrasonic air knife applicable to device

Abstract

The utility model relates to a composite membrane preparation device based on interfacial polymerization and an ultrasonic air knife suitable for the device, comprising a water phase solution processing mechanism, the water phase solution processing mechanism comprises a water phase solution tank and an ultrasonic air knife, and the ultrasonic air knife comprises a negative pressure cavity and an ultrasonic generator. An airflow hole is formed in the middle position of the bottom, facing the base membrane, of the negative pressure cavity, the ultrasonic generator comprises a first ultrasonic generator and a second ultrasonic generator, and the first ultrasonic generator and the second ultrasonic generator are arranged in the negative pressure cavity and located on the two sides of the airflow hole; a base membrane is treated by the water-phase solution tank and then is treated by an ultrasonic air knife to obtain a base membrane with a water-phase monomer layer; and the oil-phase solution treatment mechanism is used for coating an oil-phase solution on the surface of the base membrane with the water-phase monomer layer. The ultrasonic air knife is adopted to remove redundant water phase solution on the surface of the base membrane, and the water phase solution is uniformly distributed on the surface of the base membrane, so that the interfacial polymerization reaction is further promoted, and the performance of the composite membrane is further improved.

Description

Technical Field

[0001] The utility model relates to the technical field of composite film preparation, in particular to a composite film preparation device based on interfacial polymerization and an ultrasonic air knife suitable for the device. Background Art

[0002] With the advancement of industrialization, global environmental issues have led to a more prominent water resource problem. In particular, freshwater resources available for human consumption only account for 2.8% of the Earth's total water supply. Improving water environmental conditions and efficiently treating wastewater for its proper utilization are currently top priorities. Reverse osmosis and nanofiltration technologies, due to their simple preparation and excellent separation performance, have attracted widespread attention and recognition in both industrial and domestic applications. Polyamide reverse osmosis composite membranes and polyamide nanofiltration composite membranes are key components of these technologies.

[0003] Currently, polyamide reverse osmosis composite membranes and polyamide nanofiltration composite membranes are primarily composed of a non-woven fabric layer, a porous support layer, and a polyamide functional layer. The preparation of polyamide composite membranes involves numerous steps. First, the non-woven fabric and porous support membrane form a base membrane, which is then exposed to an aqueous solution. Excess aqueous solution is then removed through roller extrusion and conventional air knives. This forms a water-phase monomer layer on the surface of the base membrane, which is then exposed to an oil-phase solution. During this process, the aqueous and oil-phase monomers on the surface of the base membrane come into full contact, undergoing interfacial polymerization. Subsequently, a series of post-processing steps, including drying, produce the final polyamide composite membrane.

[0004] However, the conventional air-blowing knife in the conventional composite membrane preparation device rapidly blows away the moisture on the membrane surface through a high-speed airflow to remove the moisture on the membrane surface. This air-blowing knife cannot evenly distribute the aqueous solution on the base membrane. Since the performance of the polyamide composite membrane mainly depends on its polyamide functional layer, which is formed on the base membrane through interfacial polymerization, the uniform distribution of the aqueous solution on the base membrane is crucial to the film-forming effect. Uneven distribution will lead to differences in thickness and structure in different areas of the membrane, further leading to uneven pore structure on the membrane, reducing the transmission efficiency of water molecules, thereby reducing the water flux of the membrane. At the same time, the desalination effect in certain areas may be poor, affecting the overall desalination rate. Therefore, it is urgent to optimize the preparation device of the polyamide composite membrane to improve the overall performance and stability of the membrane. Utility Model Content

[0005] Based on this, the purpose of the present invention is to overcome the defects or shortcomings of the prior art and provide a composite membrane preparation device based on interfacial polymerization.

[0006] A composite membrane preparation device based on interfacial polymerization includes an aqueous solution processing mechanism, which includes an aqueous solution tank and an ultrasonic air knife, wherein the ultrasonic air knife includes a negative pressure chamber and an ultrasonic generator, the negative pressure chamber has an air flow hole at the middle position of the bottom facing the basement membrane, and the ultrasonic generator includes a first ultrasonic generator and a second ultrasonic generator, and the first ultrasonic generator and the second ultrasonic generator are arranged inside the negative pressure chamber and on both sides of the air flow hole; the basement membrane is treated by the aqueous solution tank and then by the ultrasonic air knife to obtain a basement membrane with an aqueous monomer layer; an oil phase solution processing mechanism, which coats the surface of the basement membrane with the aqueous monomer layer with an oil phase solution.

[0007] Compared with the existing technology, the composite membrane preparation device based on interfacial polymerization described in the utility model uses an ultrasonic air knife to remove excess aqueous solution on the surface of the base membrane and make the aqueous solution evenly distributed on the surface of the base membrane, which will further promote the interfacial polymerization reaction and thus improve the performance of the composite membrane.

[0008] Furthermore, the ultrasonic air knife also includes an ultrasonic cavity, which includes a first ultrasonic cavity and a second ultrasonic cavity. The first ultrasonic cavity and the second ultrasonic cavity are respectively arranged inside the negative pressure cavity and on both sides of the airflow hole. The first ultrasonic cavity and the second ultrasonic cavity both have sound holes at the bottom of the cavity facing the basement membrane. The first ultrasonic generator is arranged above the sound hole of the first ultrasonic cavity, and the second ultrasonic generator is arranged above the sound hole of the second ultrasonic cavity.

[0009] Furthermore, the aqueous solution processing mechanism further includes a pressure roller, which is arranged between the aqueous solution tank and the ultrasonic air knife.

[0010] Furthermore, the pressing roller includes a first pressing roller and a second pressing roller, and the first pressing roller and the second pressing roller are arranged opposite to each other with a gap therebetween.

[0011] Furthermore, the oil phase solution processing mechanism includes an oil phase solution coating head and an oil phase solution coating bottom roller, and the oil phase solution coating head and the oil phase solution coating bottom roller are arranged opposite to each other.

[0012] Furthermore, it also includes a transmission mechanism, which includes a unwinding shaft, a guide roller and a winding shaft, wherein the unwinding shaft is arranged at the entry end of the base film to release and unfold the rolled base film; the guide roller can be arranged at various positions of the preparation device to ensure that the base film can be correctly conveyed and positioned in each preparation stage; the winding shaft is arranged at the output end of the prepared composite film to wind the composite film for easy storage, transportation and subsequent use.

[0013] Furthermore, the drying and cleaning mechanism is further included. The drying and cleaning mechanism is arranged after the oil phase solution treatment mechanism, and includes a first oven, a hot water tank and a second oven arranged in sequence.

[0014] At the same time, the utility model also provides an ultrasonic air knife suitable for the preparation of interfacial polymerization composite membranes, comprising a negative pressure chamber, wherein the negative pressure chamber has an air flow hole at the bottom middle position facing the base membrane; an ultrasonic generator, wherein the ultrasonic generator comprises a first ultrasonic generator and a second ultrasonic generator, and the first ultrasonic generator is arranged inside the negative pressure chamber and on both sides of the air flow hole.

[0015] Furthermore, the ultrasonic air knife also includes a vacuum pump, which is connected to the negative pressure chamber and extracts air from the negative pressure chamber.

[0016] Furthermore, the ultrasonic air knife also includes an ultrasonic cavity, which includes a first ultrasonic cavity and a second ultrasonic cavity. The first ultrasonic cavity and the second ultrasonic cavity are respectively arranged inside the negative pressure cavity and on both sides of the airflow hole. The first ultrasonic cavity and the second ultrasonic cavity both have sound holes at the bottom of the cavity facing the basement membrane. The first ultrasonic generator is arranged above the sound hole of the first ultrasonic cavity, and the second ultrasonic generator is arranged above the sound hole of the second ultrasonic cavity.

[0017] In order to better understand and implement the present invention, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram showing the distribution structure of various mechanisms of the preparation device involved in the embodiment of the present utility model;

[0019] Figure 2 This is a structural diagram of the ultrasonic air knife involved in an embodiment of the present utility model. DETAILED DESCRIPTION

[0020] The utility model optimizes and improves the air knife device that affects the distribution of the aqueous phase solution, and proposes a composite membrane preparation device based on interfacial polymerization with an ultrasonic air knife, which is used to remove excess aqueous phase solution on the surface of the base membrane and make the aqueous phase solution evenly distributed on the base membrane, further promote the interfacial polymerization reaction and thus improve the overall performance and stability of the membrane.

[0021] The solution of the utility model is described in detail below with reference to the accompanying drawings.

[0022] Example

[0023] like Figure 1As shown, an embodiment of the present invention proposes a composite membrane preparation device based on interfacial polymerization, which includes a transmission mechanism 1 and an aqueous solution processing mechanism 2, an oil solution processing mechanism 3 and a drying and cleaning mechanism 4 arranged in sequence.

[0024] Under the action of the transmission mechanism 1, the base membrane first passes through the aqueous solution processing mechanism 2, so that the aqueous solution is evenly distributed on the surface of the base membrane. Then the base membrane with an aqueous monomer layer on the surface passes through the oil solution processing mechanism 3. During this process, the oil solution is evenly coated on the base membrane. At this time, the aqueous phase and the oil phase undergo interfacial polymerization reaction, and a polyamide functional layer is formed on the surface of the base membrane. Finally, it undergoes a series of drying and cleaning treatments by the drying and cleaning mechanism 4 to finally obtain a polyamide composite membrane.

[0025] The transmission mechanism 1 includes a unwinding shaft 11, a guide roller 12 and a winding shaft 13, wherein the unwinding shaft 11 is arranged at the entry end of the base film to release and unfold the rolled base film; the guide roller 12 can be arranged at various positions of the preparation device to ensure that the base film can be correctly conveyed and positioned in each preparation stage; the winding shaft 13 is arranged at the output end of the prepared polyamide composite film to wind the polyamide composite film for easy storage, transportation and subsequent use.

[0026] The aqueous solution processing mechanism 2 includes an aqueous solution tank 21, a pressure roller 22 and an ultrasonic air knife 23. After the base film is soaked in the aqueous solution tank 21, the aqueous solution is distributed on its surface. The excess aqueous solution on the surface of the base film is then removed by the pressure roller 22, and further removed by the ultrasonic air knife 23 to make the aqueous solution evenly distributed on the base film.

[0027] Specifically, the aqueous phase monomers in the aqueous phase solution used in the aqueous phase solution tank 21 are amine monomers, mainly one or more of m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, N-ethylaniline, m-phenylenediamine and dodecylamine, and the concentration of the amine monomers is 1.5-4.0 wt%.

[0028] Specifically, the pressing roller 22 includes a first pressing roller 221 and a second pressing roller 222. The first pressing roller 221 and the second pressing roller 222 are arranged opposite to each other, and there is a gap between them. The width of the gap is determined by the base film. The gap needs to ensure that the first pressing roller 221 and the second pressing roller 222 can both contact the base film and squeeze it. The base film is conveyed forward through the gap. The base film is squeezed by the pressing roller 22 to remove excess aqueous solution on the base film.

[0029] See also Figure 2 , Figure 2The structure of the ultrasonic air knife 23 includes a vacuum pump 231, a negative pressure chamber 232, an ultrasonic chamber 233, and an ultrasonic generator 234. The vacuum pump 231 is connected to the negative pressure chamber 232 and extracts the air therein, thereby reducing the pressure in the negative pressure chamber 232, making the negative pressure chamber 232 a negative pressure environment. The negative pressure chamber 232 has an air flow hole at the middle position of the bottom facing the basement membrane. The ultrasonic chamber 233 includes a first ultrasonic chamber 233a and a second ultrasonic chamber 233b. The first ultrasonic chamber 233a and the second ultrasonic chamber 233b are respectively arranged inside the negative pressure chamber 232 and on both sides of the air flow hole. The first ultrasonic chamber 233a and the second ultrasonic chamber 233b both have acoustic holes at the bottom of the chamber facing the basement membrane. The ultrasonic generator 234 includes a first ultrasonic generator 234a and a second ultrasonic generator 234b. The first ultrasonic generator 234a is arranged at the upper part of the sound hole of the first ultrasonic cavity 233a, and the second ultrasonic generator 234b is arranged at the upper part of the sound hole of the second ultrasonic cavity 233b.

[0030] The negative pressure chamber 232 first absorbs the excess aqueous solution from the surface of the basement membrane to ensure that too much aqueous solution does not accumulate on the surface of the basement membrane; then the first ultrasonic generator 234a and the second ultrasonic generator 234b respectively arranged in the first ultrasonic chamber 233a and the second ultrasonic chamber 233b generate ultrasonic waves to break up the aqueous solution on the surface of the basement membrane, and at the same time, the ultrasonic vibration generated by the ultrasonic waves causes the broken aqueous solution to be redistributed on the surface of the basement membrane, thereby forming a basement membrane surface with a uniform distribution of aqueous solution.

[0031] The oil-phase solution processing mechanism 3 includes an oil-phase solution coating head 31 and an oil-phase solution coating roller 32. The oil-phase solution coating head 31 and the oil-phase solution coating roller 32 are positioned opposite each other with a gap therebetween. This gap ensures that both the oil-phase solution coating head 31 and the oil-phase solution coating roller 32 can contact and squeeze the base film. The base film is transferred to the oil-phase solution coating roller 32, where the oil-phase solution coating head 31 uniformly coats the oil-phase solution onto the base film having the aqueous monomer layer.

[0032] Specifically, the oil phase monomer in the oil phase solution used by the oil phase solution coating head 31 is an acyl chloride monomer, mainly one or more of trimesoyl chloride, phthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, benzoyl chloride, propionyl chloride, succinoyl chloride, trisuccinoyl chloride and hexanoyl chloride, and the concentration of the acyl chloride monomer is 0.12~0.2wt%.

[0033] Specifically, tributyl phosphate is added as an additive to the oil phase solution used by the oil phase solution coating head 31 to reasonably regulate the interfacial polymerization reaction rate of the aqueous phase monomer and the oil phase monomer. The concentration of the additive is 0.2-1 wt %.

[0034] The drying and cleaning mechanism 4 includes a first oven 41, a hot water tank 42 and a second oven 43, which are arranged in sequence. The temperature of the first oven 41 is between 70 and 120°C, preferably between 85 and 100°C; the drying time of the first oven 41 is set to 1 to 10 minutes, preferably between 1 and 2.5 minutes; the temperature of the hot water in the hot water tank 42 is 70°C; the temperature and time of the second oven 43 are not specifically limited, and are used to dry the composite film that has been immersed in the hot water tank 42 for cleaning.

[0035] When preparing a composite film according to the present invention, the base film enters the aqueous solution tank 21 at a certain speed through the unwinding shaft 11 and the guide roller 12 for immersion. After the base film comes out of the aqueous solution tank 21, it is first squeezed by the pressure roller 22 to remove excess aqueous solution, and then the ultrasonic air knife 23 is used to further remove excess aqueous solution and redistribute the aqueous solution on the surface of the base film. Then, the base film with the aqueous monomer layer passes through the oil phase solution coating head 31 and the oil phase solution coating bottom roller 32 to work together to evenly coat the oil phase solution on the base film. At this time, the aqueous monomer and the oil phase monomer undergo interfacial polymerization reaction, and the surface of the base film is reacted to obtain a polyamide functional layer, which is then dried in the first oven 41 to obtain an initial polyamide composite film, which is then washed in the hot water tank 42 and dried in the second oven 43, and finally the polyamide composite film is obtained through the rewinding shaft 13.

[0036] Experimental verification

[0037] Comparative Example 1

[0038] The preparation device used in this comparative example 1 is basically the same as that in the embodiment, except that the ultrasonic air knife 23 is removed, that is, after the base film comes out of the aqueous solution tank 21, the excess aqueous solution is only squeezed out by the pressing roller 22.

[0039] Comparative Example 2

[0040] The preparation device used in this comparative example 1 is basically the same as that in the embodiment, except that an ordinary air blowing knife is used instead of the ultrasonic air knife 23, that is, after the base film comes out of the aqueous solution tank 21, it is first squeezed by the pressure roller 22 to remove excess aqueous solution, and then the excess aqueous solution is further removed by the ordinary air blowing knife.

[0041] Verify the results

[0042] In order to verify the performance difference between the polyamide composite membrane prepared by the preparation device involved in the embodiment of the present invention and the polyamide composite membrane prepared by the preparation device involved in Comparative Example 1 and Comparative Example 2, the parameters in the membrane preparation process such as membrane operation speed, aqueous phase solution and its concentration, oil phase solution and its concentration, oven temperature and time, subsequent cleaning process and time were kept consistent. The water flux and salt rejection rate of the prepared polyamide composite membrane were tested using the GB / T 32373-2015 reverse osmosis membrane testing method. The results are shown in Table 1.

[0043] Table 1

[0044]

[0045]

[0046] Table 1

[0047]

[0048] The above data show that the polyamide composite membrane produced by using a pressure roller and ultrasonic air knife to remove excess aqueous solution and evenly distribute the aqueous solution on the surface of the base membrane has higher water flux and desalination rate, and the membrane performance is more stable.

[0049] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application. The singular forms of "a", "said" and "the" used in the embodiments of the present application and the claims are also intended to include plural forms, unless the context clearly indicates other meanings. When the above description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of the present application, for those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0050] The above-described embodiments merely represent implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the concept of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A composite membrane preparation device based on interfacial polymerization, characterized in that: include An aqueous solution treatment mechanism comprising an aqueous solution tank and an ultrasonic air knife, wherein the ultrasonic air knife comprises a negative pressure chamber and an ultrasonic generator, wherein the negative pressure chamber has an air flow hole at a central position on the bottom of the basement membrane, and the ultrasonic generator comprises a first ultrasonic generator and a second ultrasonic generator, wherein the first ultrasonic generator and the second ultrasonic generator are arranged inside the negative pressure chamber and on both sides of the air flow hole; after the basement membrane is treated in the aqueous solution tank, it is then treated with the ultrasonic air knife to obtain a basement membrane having an aqueous monomer layer; An oil phase solution processing mechanism is used to apply the oil phase solution to the surface of the base film having the water phase monomer layer.

2. The composite membrane preparation device based on interfacial polymerization according to claim 1, characterized in that: The ultrasonic air knife also includes an ultrasonic cavity, which includes a first ultrasonic cavity and a second ultrasonic cavity. The first ultrasonic cavity and the second ultrasonic cavity are respectively arranged inside the negative pressure cavity and on both sides of the airflow hole. The first ultrasonic cavity and the second ultrasonic cavity both have sound holes at the bottom of the cavity facing the basement membrane. The first ultrasonic generator is arranged above the sound hole of the first ultrasonic cavity, and the second ultrasonic generator is arranged above the sound hole of the second ultrasonic cavity.

3. The composite membrane preparation device based on interfacial polymerization according to claim 2, characterized in that: The aqueous solution processing mechanism further includes a pressure roller, which is arranged between the aqueous solution tank and the ultrasonic air knife.

4. The composite membrane preparation device based on interfacial polymerization according to claim 3, characterized in that: The pressing roller includes a first pressing roller and a second pressing roller. The first pressing roller and the second pressing roller are arranged opposite to each other with a gap therebetween.

5. The composite membrane preparation device based on interfacial polymerization according to claim 4, characterized in that: The oil phase solution processing mechanism comprises an oil phase solution coating head and an oil phase solution coating bottom roller, and the oil phase solution coating head and the oil phase solution coating bottom roller are arranged opposite to each other.

6. The composite membrane preparation device based on interfacial polymerization according to claim 1, characterized in that: It also includes a transmission mechanism, which includes a unwinding shaft, a guide roller and a winding shaft, wherein the unwinding shaft is arranged at the entry end of the base film, the guide roller can be arranged at various positions of the preparation device, and the winding shaft is arranged at the output end of the prepared composite film.

7. The composite membrane preparation device based on interfacial polymerization according to claim 6, characterized in that: It also includes a drying and cleaning mechanism, which is arranged after the oil phase solution processing mechanism and includes a first oven, a hot water tank and a second oven arranged in sequence.

8. An ultrasonic air knife suitable for preparing interfacial polymerization composite membranes, characterized by: include a negative pressure chamber, wherein the negative pressure chamber has an air flow hole at a middle position of the bottom facing the basement membrane; The ultrasonic generator includes a first ultrasonic generator and a second ultrasonic generator, and the first ultrasonic generator and the second ultrasonic generator are arranged inside the negative pressure chamber and on both sides of the air flow hole.

9. The ultrasonic air knife for preparing interfacial polymerization composite membrane according to claim 8, characterized in that: The ultrasonic air knife further includes a vacuum pump, which is connected to the negative pressure chamber and extracts air from the negative pressure chamber.

10. The ultrasonic air knife suitable for preparing interfacial polymerization composite membrane according to claim 9, characterized in that: The ultrasonic air knife also includes an ultrasonic cavity, which includes a first ultrasonic cavity and a second ultrasonic cavity. The first ultrasonic cavity and the second ultrasonic cavity are respectively arranged inside the negative pressure cavity and on both sides of the airflow hole. The first ultrasonic cavity and the second ultrasonic cavity both have sound holes at the bottom of the cavity facing the basement membrane. The first ultrasonic generator is arranged above the sound hole of the first ultrasonic cavity, and the second ultrasonic generator is arranged above the sound hole of the second ultrasonic cavity.

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