Composite membrane and water treatment device

Abstract

The utility model discloses a composite membrane and a water treatment device. The composite membrane comprises a desalting layer, a polyolefin base material layer and an ultrafiltration layer which are sequentially stacked. According to the composite membrane, the problem of membrane stripping of a conventional membrane layer is avoided, and macromolecular impurities and ion impurities can be removed at one time through the composite membrane, so that the production efficiency is greatly improved, and the production cost is remarkably reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of water treatment, in particular to a composite membrane and a water treatment device. Background Art

[0002] Nanofiltration membranes and reverse osmosis membranes are widely used. RO membrane systems can be seen in many places, such as hospitals, kitchens, refineries, power plants, paper mills, and semiconductor manufacturing plants. The most important applications are in seawater desalination, municipal sewage, industrial wastewater, food and beverage, and biomedical markets. However, the pore size of nanofiltration membranes and reverse osmosis membranes is extremely small. The trapped particles, colloids, macromolecules, salts and other substances are deposited on the surface of the membrane or between the pores inside the membrane, resulting in a significant increase in the resistance of water molecules to pass through the membrane, a significant decrease in the permeability of the membrane, a significant decrease in service life, and a significant increase in operating energy consumption. It is necessary to ensure that the macromolecules in the trapped liquid are removed before passing through the nanofiltration and reverse osmosis membranes. Ultrafiltration is a type of membrane separation technology with a pore size range of 0.05μm to 1nm. It can effectively intercept particles, colloids, and macromolecules. The lower limit of the molecular weight cutoff is about 1000Da, and the upper limit is generally about 50000Da. The molecular weights of proteins, viruses, starches, colloids, and pigments are all around 1000 to 50000 g / mol, so ultrafiltration membranes can be used to separate systems containing macromolecules and colloids.

[0003] At present, most large-scale water treatment equipment uses multi-membrane technology, which includes ultrafiltration membrane, reverse osmosis membrane or nanofiltration membrane. After comprehensive filtration by the above-mentioned multiple filter membranes, large particles and salts in the water to be treated are effectively filtered out. The multi-membrane process requires that the components of ultrafiltration membrane, nanofiltration membrane and reverse osmosis membrane be equipped with filtration systems respectively, and each membrane component is equipped with corresponding system components, which not only increases the cost, but also causes the system to be bloated, increases the floor space, and also increases labor.

[0004] At present, the base membranes of ultrafiltration membranes, nanofiltration membranes and reverse osmosis membranes are generally prepared by phase inversion method. The structure of existing nanofiltration membranes or reverse osmosis membranes is as follows: Figure 1 As shown, this structure includes a non-woven fabric substrate, an ultrafiltration layer, and a desalination layer formed on the surface of the ultrafiltration layer by interfacial polymerization. The above-mentioned water treatment membrane structure is an asymmetric structure, and the feed liquid can only pass through the membrane from the direction of the desalination layer. If the feed liquid passes through the base membrane in the opposite direction, the ultrafiltration layer will be separated from the non-woven fabric substrate, resulting in the destruction of the membrane.

[0005] Therefore, based on cost considerations or the effect of the membrane, the existing base membranes need to be improved. Utility Model Content

[0006] The utility model aims to solve one of the technical problems in the related art to at least a certain extent. To this end, one purpose of the utility model is to provide a composite membrane and a water treatment device. The composite membrane avoids the problem of film stripping of conventional membrane layers, and macromolecular impurities and ionic impurities can be removed at one time through the composite membrane, thereby greatly improving production efficiency and significantly reducing production costs.

[0007] In one aspect of the utility model, the utility model discloses a composite membrane. According to an embodiment of the utility model, the composite membrane comprises: a desalination layer, a polyolefin substrate layer and an ultrafiltration layer stacked in sequence.

[0008] The composite membrane according to the above embodiment of the utility model comprises a desalination layer, a polyolefin substrate layer and an ultrafiltration layer stacked in sequence. First, the polyolefin substrate layer has good acid and alkali resistance and corrosion resistance, and can be used as an excellent composite membrane substrate. The desalination layer is located on one side of the polyolefin substrate layer. Even if the solution to be purified enters the base membrane from the side of the polyolefin substrate layer away from the desalination layer, it will not cause the separation (de-filming) of the desalination layer and the polyolefin substrate layer, thereby achieving the removal of ionic impurities in the solution to be purified. The ultrafiltration layer is located on one side of the polyolefin substrate layer away from the desalination layer, and the solution to be purified flows from the ultrafiltration layer into the polyolefin substrate layer, thereby achieving the removal of macromolecular impurities in the solution to be purified. The desalination layer, the polyolefin substrate layer and the ultrafiltration layer together form an integrated composite membrane, and the solution to be purified flows through the ultrafiltration layer, the polyolefin substrate layer and the desalination layer in sequence, and the removal of macromolecular impurities and ionic impurities can be achieved in sequence, thereby obtaining a qualified purified liquid. Thus, the composite membrane avoids the problem of de-filming of conventional membrane layers, and macromolecular impurities and ionic impurities can be removed at one time by the composite membrane, thereby greatly improving production efficiency and significantly reducing production costs.

[0009] In addition, the composite film according to the above embodiment of the utility model may also have the following technical features:

[0010] In some embodiments of the present invention, the thickness of the desalination layer is 100 nm to 300 nm.

[0011] In some embodiments of the present invention, the thickness of the polyolefin substrate layer is 15 μm to 50 μm.

[0012] In some embodiments of the present invention, the thickness of the ultrafiltration layer is 10 μm to 30 μm.

[0013] In some embodiments of the present invention, the polyolefin substrate layer includes a polyolefin substrate layer that has not been hydrophilically modified.

[0014] In some embodiments of the present invention, the polyolefin substrate layer includes a polyethylene substrate layer or a polypropylene substrate layer.

[0015] In some embodiments of the present invention, the ultrafiltration layer includes a polysulfone ultrafiltration layer, a polyethersulfone ultrafiltration layer, a polyvinylidene fluoride ultrafiltration layer, a polyamide ultrafiltration layer or a polyacrylonitrile ultrafiltration layer.

[0016] In another aspect of the utility model, the utility model discloses a water treatment device. According to an embodiment of the utility model, the water treatment device includes the above-mentioned composite membrane. Thus, the water treatment device combines the traditional ultrafiltration component and the nanofiltration / reverse osmosis component into one filtration component, which can significantly reduce production costs, save equipment space, and improve production efficiency.

[0017] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0019] Figure 1 It is a schematic diagram of the structure of an existing nanofiltration membrane or reverse osmosis membrane;

[0020] Figure 2 It is a schematic structural diagram of a composite membrane according to an embodiment of the utility model. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0022] In one aspect of the present invention, the present invention discloses a composite film. According to an embodiment of the present invention, referring to Figure 2 The composite membrane includes: a desalination layer 100, a polyolefin substrate layer 200 and an ultrafiltration layer 300 which are stacked in sequence.

[0023] According to the embodiment of the utility model, the polyolefin substrate layer 200 has good acid and alkali resistance and corrosion resistance, and can be used as an excellent composite membrane substrate. The desalination layer 100 is located on one side of the polyolefin substrate layer 200. Even if the solution to be purified enters the base membrane from the side of the polyolefin substrate layer 200 away from the desalination layer 100, it will not cause the separation (de-membrane) of the desalination layer 100 and the polyolefin substrate layer 200, thereby achieving the removal of ionic impurities in the solution to be purified. It should be noted that the polyolefin substrate layer 200 and the desalination layer 100 are prepared using conventional materials in the art, and those skilled in the art can select the specific materials and preparation methods of the polyolefin substrate layer 200 and the desalination layer 100 according to actual conditions. For example, the polyolefin substrate layer 200 includes a polyethylene substrate layer or a polypropylene substrate layer.

[0024] According to an embodiment of the utility model, the thickness of the desalination layer 100 is 100nm to 300nm. The inventors found that when the thickness of the desalination layer 100 is within the above range, a better desalination effect can be achieved. When the desalination layer is less than 100nm, the desalination rate will decrease, and when it is greater than 300nm, the water flux will decrease.

[0025] According to the embodiment of the utility model, the thickness of the polyolefin substrate layer 200 is 15 μm to 50 μm. The inventors found that the thickness of the polyolefin substrate layer 200 within the above range can better play a supporting and water permeable role. The polyolefin substrate is less than 15 μm, the strength is poor, and it is easy to deform and damage; the polyolefin substrate is greater than 50 μm, the water permeability is poor, which affects the water flux of the composite membrane.

[0026] According to an embodiment of the utility model, the polyolefin substrate layer 200 includes a polyolefin substrate layer that is not hydrophilically modified. At present, if polyolefin is used as the substrate of the membrane, because the hydrophobicity of the polyolefin material is strong, in order to improve the hydrophilicity of the polyolefin, it will be hydrophilically modified. However, the present application is provided with an ultrafiltration layer 300 on one side of the polyolefin substrate layer 200 away from the desalination layer 100, and there is a good mutual contact between the ultrafiltration layer 300 and the polyolefin substrate layer 200. Specifically, when the ultrafiltration layer 300 is coated on the polyolefin substrate layer 200, the casting liquid will penetrate into the interior of the polyolefin substrate, and the hydrophilic components of the casting liquid will adhere to the interior of the substrate as the casting liquid forms a film, thereby modifying the polyolefin substrate, greatly increasing the hydrophilicity of the substrate, thereby opening the pores for ions to pass through the polyolefin substrate layer 200, and therefore, the polyolefin substrate layer 200 of the present application adopts a polyolefin substrate layer that is not hydrophilically modified and can also achieve the purification of the solution. It can be understood by those skilled in the art that, based on the composite membrane structure of the present application, the polyolefin substrate layer 200 of the present application can be a hydrophilically modified polyolefin substrate layer or a non-hydrophilically modified polyolefin substrate layer, and no special limitation is made here. It should be noted that the hydrophilic modification method of the polyolefin substrate layer 200 is a conventional method in the art, and those skilled in the art can select it according to actual conditions.

[0027] According to an embodiment of the utility model, the ultrafiltration layer 300 is located on a side of the polyolefin substrate layer 200 away from the desalination layer 100, and the liquid to be purified flows from the ultrafiltration layer 300 into the polyolefin substrate layer 200, which can achieve the removal of macromolecular impurities in the solution to be purified. The desalination layer 100, the polyolefin substrate layer 200 and the ultrafiltration layer 300 together form an integrated composite membrane, and the solution to be purified flows through the ultrafiltration layer 300, the polyolefin substrate layer 200 and the desalination layer 100 in sequence, which can achieve the removal of macromolecular impurities and ionic impurities in sequence, thereby obtaining a qualified purified liquid. It should be noted that the ultrafiltration layer 300 is prepared using conventional materials in the art, and those skilled in the art can select according to actual conditions, for example, the ultrafiltration layer 300 includes a polysulfone ultrafiltration layer, a polyethersulfone ultrafiltration layer, a polyvinylidene fluoride ultrafiltration layer, a polyamide ultrafiltration layer or a polyacrylonitrile ultrafiltration layer.

[0028] According to the embodiment of the utility model, the thickness of the ultrafiltration layer 300 is 10 μm to 30 μm. The inventors found that when the thickness of the ultrafiltration layer 300 is within the above range, the ultrafiltration layer can have better separation ability. When the ultrafiltration layer is greater than 30 μm, the flux will decrease, and when it is less than 10 μm, the retention capacity of the membrane will decrease, both of which will affect the separation performance of the ultrafiltration layer.

[0029] In another aspect of the utility model, the utility model discloses a water treatment device. According to an embodiment of the utility model, the water treatment device includes the above-mentioned composite membrane. As a result, the water treatment device combines the traditional ultrafiltration component and the nanofiltration / reverse osmosis component into a filtration component, which can significantly reduce production costs, save equipment space, and improve production efficiency. It should be noted that the features and advantages described above for the composite membrane are also applicable to the water treatment device and will not be repeated here.

[0030] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" 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 representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0031] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A composite film, characterized in that include: The desalination layer, polyolefin substrate layer and ultrafiltration layer are stacked in sequence.

2. The composite membrane according to claim 1, characterized in that The thickness of the desalting layer is 100nm to 300nm.

3. The composite membrane according to claim 1, characterized in that The thickness of the polyolefin substrate layer is 15 μm to 50 μm.

4. The composite membrane according to claim 1, characterized in that The thickness of the ultrafiltration layer is 10 μm to 30 μm.

5. The composite membrane according to claim 1, characterized in that The polyolefin substrate layer includes a polyolefin substrate layer that has not been hydrophilically modified.

6. The composite membrane according to claim 1, characterized in that The polyolefin substrate layer includes a polyethylene substrate layer or a polypropylene substrate layer.

7. The composite membrane according to claim 1, characterized in that The ultrafiltration layer includes a polysulfone ultrafiltration layer, a polyethersulfone ultrafiltration layer, a polyvinylidene fluoride ultrafiltration layer, a polyamide ultrafiltration layer or a polyacrylonitrile ultrafiltration layer.

8. A water treatment device, characterized in that: The composite film comprises the composite film according to any one of claims 1 to 7.

Images