Low-energy-consumption anti-pollution reverse osmosis membrane element and preparation method thereof

Abstract

The invention discloses a low-energy-consumption anti-pollution reverse osmosis membrane element and a preparation method thereof, and belongs to the technical field of membrane separation. The reverse osmosis membrane element comprises a central pipe, a plurality of water inlet separation nets and a plurality of reverse osmosis membrane bag units, the water inlet separation nets and the reverse osmosis membrane bag units are sequentially stacked and wound on the central pipe, each water inlet separation net is of a double-layer discontinuous net structure, and each reverse osmosis membrane comprises three layers of structures: the lowest layer is a base membrane, the middle layer is a supporting layer, and the bottom layer is a water inlet layer. An uppermost separation layer; the main preparation process comprises the following steps: preparing materials, preparing a reverse osmosis membrane supporting layer, preparing a reverse osmosis membrane separating layer and rolling the reverse osmosis membrane element. The anti-pollution performance of the reverse osmosis membrane is improved through burdening and a preparation process of the reverse osmosis membrane, and the resistance and the energy consumption are reduced by utilizing the structure of the water inlet separation net.

Description

Technical Field

[0001] The present invention belongs to the technical field of membrane separation, and in particular relates to a low-energy-consumption, anti-pollution reverse osmosis membrane element and a preparation method thereof. Background Art

[0002] Membrane separation technology, the preferred water treatment technology of the 21st century, has been widely used in the fields of deep drinking water purification, seawater and brackish water desalination, sewage and wastewater treatment and recovery, and ultrapure water production. The main membrane separation processes include microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO). Reverse osmosis membrane separation technology utilizes the principle of reverse osmosis for separation, and its characteristics are as follows: (1) It can separate solutes and water without phase change at room temperature, and is suitable for the separation and concentration of heat-sensitive substances. Compared with separation methods with phase change, it has lower energy consumption. (2) The impurity removal range is wide, not only can it remove dissolved inorganic salts, but also can remove various organic impurities; (3) High salt removal rate, capable of intercepting solutes with particle sizes larger than a few nanometers; (4) Since only pressure is used as the driving force for membrane separation, the separation device is simple, easy to operate, self-control and maintain; (5) Since the reverse osmosis device must operate under high pressure, it must be equipped with a high-pressure pump and high-pressure resistant pipelines; (6) The reverse osmosis membrane device requires that the incoming water must meet certain indicators to operate normally. Therefore, certain pretreatment measures must be taken before the raw water enters the reverse osmosis device. In order to extend the service life of the membrane, the membrane must be cleaned regularly to remove dirt.

[0003] When using a reverse osmosis membrane to separate water and solutes, even if the raw water is properly pretreated, impurities in the water will still accumulate on the surface of the membrane and contaminate the membrane, resulting in a decrease in the membrane's separation rate or water permeability, or both.

[0004] Currently, the main issues hindering the wider application and promotion of reverse osmosis membrane elements include membrane fouling and energy consumption. Reverse osmosis membrane fouling primarily depends on the membrane material and manufacturing process. Energy consumption of reverse osmosis membrane elements not only depends on the osmotic pressure of the membrane itself, but also on the flow resistance of the membrane element, which also increases energy consumption. Summary of the Invention

[0005] The object of the present invention is to provide a reverse osmosis membrane element with strong anti-pollution ability, small flow resistance and low energy consumption and a preparation method thereof.

[0006] The present invention provides a low-energy consumption and anti-pollution reverse osmosis membrane element, which includes a central tube, a water inlet spacer and a reverse osmosis membrane bag unit. The water inlet spacer and the reverse osmosis membrane bag unit are several layers stacked and wound on the central tube in sequence. The water inlet spacer is a double-layer non-continuous network structure, the spacer layer A is a parallel line along the direction of water flow, and the spacer layer B is an oblique interwoven line. The reverse osmosis membrane bag unit is a rectangular three-layer structure, the first and third layers are reverse osmosis membranes, and the second middle layer is a water production diversion net. The three sides of the rectangle of the membrane bag unit are sealed, and the fourth side is connected to the central tube. The reverse osmosis membrane contains a three-layer structure: the bottom layer is a base membrane, the middle layer is a support layer, and the top layer is a separation layer.

[0007] The reverse osmosis membrane of the present invention has a support layer which is an ultrafiltration membrane based on polyphenylene sulfone and contains (by weight percentage): High molecular weight polymer - polyphenylene sulfone (PPSU): 10% to 20%, Solvent-dimethylacetamide (DMAC): 63-86%, Additives - lithium chloride (LiCl): 1-4%, Additives - polyethylene glycol 400 (PEG-400): 1-5%, Additives - Polyvinylpyrrolidone (PVP): 2-8%.

[0008] The reverse osmosis membrane of the present invention has a separation layer which is a highly cross-linked polyamide separation layer. The formation process is that the polyamide separation layer is formed by cross-linking solution A and solution B. The formulation of solution A contains (by weight percentage): High molecular weight polymer-m-phenylenediamine: 0.05%~2%, Solvent-water: 96~99.89% Additives - sodium lauryl sulfate: 0.02-2%, Additive-trihexylamine: 0.02~2%, Additive-ethanol: 0.02-2%; The formulation of Solution B contains (by weight percentage): High molecular weight polymer-trimesoyl chloride: 0.05~2.5%, Solvent-n-hexane: 95.5~99.93%, Additive-propanol: 0.02~2%.

[0009] The method for preparing a reverse osmosis membrane of the present invention comprises the following steps in sequence: Step 1: coating a support layer on the base film, and then washing and removing water; Step 2, coating solution A on the base film treated in step 1; Step 3, coating the base film prepared in step 2 with solution B; Step 4: solidifying, rinsing, and drying the membrane obtained in step 3 to obtain the reverse osmosis membrane.

[0010] The method for preparing a reverse osmosis membrane element of the present invention comprises the following steps in sequence: Step 1: stack the cut rectangular reverse osmosis membrane, water production diversion net, and reverse osmosis membrane from top to bottom, and seal the three sides to form a reverse osmosis membrane bag unit; Step 2: stack several water inlet screens and reverse osmosis membrane bag units in sequence, roll them around the central tube and fix them; Step 3: Based on the above step 2, the outer shell is further packaged to produce the reverse osmosis membrane element. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the specific embodiments of the present invention, the following briefly introduces the drawings required for use in the specific embodiments.

[0012] Figure 1 It is a schematic diagram of the structure of the reverse osmosis membrane element; Figure 2 It is a structural diagram of the reverse osmosis membrane bag unit; Figure 3 It is a schematic diagram of the water inlet screen; Among them, 1 is the central tube, 2 is the water inlet screen, 3 is the reverse osmosis membrane bag unit, 4 is the reverse osmosis membrane, 5 is the water production diversion net, 6 is the screen A layer, and 7 is the screen B layer. DETAILED DESCRIPTION

[0013] The following examples are provided to help better understand the present invention, rather than to limit the present invention described in detail in the claims. Example 1

[0014] The low-energy consumption and anti-pollution reverse osmosis membrane element of this embodiment 1 comprises a central tube (1), a water inlet spacer (2) and a reverse osmosis membrane bag unit (3), wherein the water inlet spacer (2) and the reverse osmosis membrane bag unit (3) are several layers stacked and wound on the central tube (1), the water inlet spacer (2) is a double-layer non-continuous network structure, the spacer A layer is a parallel line along the direction of water flow, and the spacer B layer is an oblique interwoven line, the reverse osmosis membrane bag unit (3) is a rectangular three-layer structure, the first and third layers are reverse osmosis membranes (4), and the second middle layer is a water production diversion net (5), the three sides of the rectangular membrane bag unit are sealed, and the fourth side is connected to the central tube (1), and the reverse osmosis membrane (4) has a three-layer structure: the bottom layer is a base membrane, the middle layer is a support layer, and the top layer is a separation layer.

[0015] The reverse osmosis membrane (4) of this embodiment 1 has a support layer which is an ultrafiltration membrane based on polyphenylene sulfone and contains (by weight percentage): High molecular weight polymer - polyphenylene sulfone (PPSU): 12%, Solvent-dimethylacetamide (DMAC): 82%, Additive - lithium chloride (LiCl): 1%, Additives - Polyethylene glycol 400 (PEG-400): 3%, Additive - Polyvinylpyrrolidone (PVP): 2%.

[0016] The reverse osmosis membrane (4) of this embodiment 1 has a separation layer which is a highly cross-linked polyamide separation layer. The formation process is that the solution A and the solution B are cross-linked to form the polyamide separation layer. The formulation of solution A contains (by weight percentage): High molecular weight polymer-m-phenylenediamine: 1%, Solvent - Water: 98.55%, Additives - sodium lauryl sulfate: 0.05%, Additive-trihexylamine: 0.2%, Additive-ethanol: 0.2%; The formulation of Solution B contains (by weight percentage): High molecular weight polymer-trimesoyl chloride: 1.05%, Solvent-n-hexane: 98.85%, Additive - Propanol: 0.1%.

[0017] The method for preparing the reverse osmosis membrane (4) of this embodiment 1 comprises the following steps in sequence: Step 1: coating a support layer on the base film, and then washing and removing water; Step 2, coating solution A on the base film treated in step 1; Step 3, coating the base film prepared in step 2 with solution B; Step 4: solidifying, rinsing, and drying the membrane obtained in step 3 to obtain the reverse osmosis membrane.

[0018] The method for preparing the reverse osmosis membrane element of this embodiment 1 comprises the following steps in sequence: Step 1: stack the cut rectangular reverse osmosis membrane (4), the water production diversion net (5), and the reverse osmosis membrane (4) in order from top to bottom, and seal the three sides to form a reverse osmosis membrane bag unit (3); Step 2: stacking a plurality of water inlet screens (2) and reverse osmosis membrane bag units (3) in sequence, rolling them around the central tube (1) and fixing them; Step 3: Based on the above step 2, the outer shell is further packaged to produce the reverse osmosis membrane element. Example 2

[0019] The low-energy consumption and anti-pollution reverse osmosis membrane element of this embodiment 2 comprises a central tube (1), a water inlet spacer (2) and a reverse osmosis membrane bag unit (3), wherein the water inlet spacer (2) and the reverse osmosis membrane bag unit (3) are several layers stacked and wound on the central tube (1), the water inlet spacer (2) is a double-layer non-continuous network structure, the spacer A layer is a parallel line along the direction of water flow, and the spacer B layer is an oblique interwoven line, the reverse osmosis membrane bag unit (3) is a rectangular three-layer structure, the first and third layers are reverse osmosis membranes (4), and the second middle layer is a water production diversion net (5), the three sides of the rectangular membrane bag unit are sealed, and the fourth side is connected to the central tube (1), and the reverse osmosis membrane (4) has a three-layer structure: the bottom layer is a base membrane, the middle layer is a support layer, and the top layer is a separation layer.

[0020] The reverse osmosis membrane (4) of this embodiment 2 has a support layer which is an ultrafiltration membrane based on polyphenylene sulfone and contains (by weight percentage): High molecular weight polymer - polyphenylene sulfone (PPSU): 15%, Solvent-dimethylacetamide (DMAC): 73%, Additive - lithium chloride (LiCl): 2.5%, Additives - Polyethylene glycol 400 (PEG-400): 2.5%, Additives - Polyvinylpyrrolidone (PVP): 6%.

[0021] The reverse osmosis membrane (4) of this embodiment 2 has a separation layer which is a highly cross-linked polyamide separation layer. The formation process is that the solution A and the solution B are cross-linked to form the polyamide separation layer. The formulation of solution A contains (by weight percentage): High molecular weight polymer-m-phenylenediamine: 0.5%, Solvent-water: 97%, Additives - sodium lauryl sulfate: 0.8%, Additive-trihexylamine: 1.2%, Additive-ethanol: 0.5%; The formulation of Solution B contains (by weight percentage): High molecular weight polymer-trimesoyl chloride: 1.3%, Solvent-n-hexane: 98.5%, Additive - Propanol: 0.2%.

[0022] The method for preparing the reverse osmosis membrane (4) of this embodiment 2 comprises the following steps in sequence: Step 1: coating a support layer on the base film, and then washing and removing water; Step 2, coating solution A on the base film treated in step 1; Step 3, coating the base film prepared in step 2 with solution B; Step 4: solidifying, rinsing, and drying the membrane obtained in step 3 to obtain the reverse osmosis membrane.

[0023] The method for preparing the reverse osmosis membrane element of this embodiment 2 comprises the following steps in sequence: Step 1: stack the cut rectangular reverse osmosis membrane (4), the water production diversion net (5), and the reverse osmosis membrane (4) in order from top to bottom, and seal the three sides to form a reverse osmosis membrane bag unit (3); Step 2: stacking a plurality of water inlet screens (2) and reverse osmosis membrane bag units (3) in sequence, rolling them around the central tube (1) and fixing them; Step 3: Based on the above step 2, the outer shell is further packaged to produce the reverse osmosis membrane element.

[0024] The present invention improves the anti-pollution performance of the reverse osmosis membrane itself through the ingredients and preparation process of the reverse osmosis membrane, and utilizes the structure of the water inlet screen to reduce resistance and lower energy consumption.

Claims

1. A low-energy consumption and anti-pollution reverse osmosis membrane element, characterized in that: It includes a central tube, a water inlet spacer and a reverse osmosis membrane bag unit. The water inlet spacer and the reverse osmosis membrane bag unit are several layers stacked and wound on the central tube in sequence. The water inlet spacer is a double-layer non-continuous network structure. The spacer A layer is a parallel line along the direction of water flow, and the spacer B layer is an oblique interwoven line. The reverse osmosis membrane bag unit is a rectangular three-layer structure. The first and third layers are reverse osmosis membranes, and the second middle layer is a water production diversion net. The three sides of the rectangle of the membrane bag unit are sealed, and the fourth side is connected to the central tube. The reverse osmosis membrane contains a three-layer structure: the bottom layer is a base membrane, the middle layer is a support layer, and the top layer is a separation layer.

2. The reverse osmosis membrane according to claim 1, wherein the support layer is an ultrafiltration membrane based on polyphenylene sulfone, comprising (by weight percentage): High molecular weight polymer - polyphenylene sulfone (PPSU): 10% to 20%, Solvent-dimethylacetamide (DMAC): 63-86%, Additives - lithium chloride (LiCl): 1-4%, Additives - polyethylene glycol 400 (PEG-400): 1-5%, Additives - Polyvinylpyrrolidone (PVP): 2-8%.

3. The reverse osmosis membrane according to claim 1, wherein the separation layer is characterized by a highly cross-linked polyamide separation layer, which is formed by cross-linking solution A and solution B to form the polyamide separation layer. The formulation of solution A contains (by weight percentage): High molecular weight polymer-m-phenylenediamine: 0.05%~2%, Solvent-water: 96~99.89% Additives - sodium lauryl sulfate: 0.02-2%, Additive-trihexylamine: 0.02~2%, Additive-ethanol: 0.02-2%; The formulation of Solution B contains (by weight percentage): High molecular weight polymer-trimesoyl chloride: 0.05~2.5%, Solvent-n-hexane: 95.5~99.93%, Additive-propanol: 0.02~2%.

4. The method for preparing a reverse osmosis membrane according to claim 1, wherein Contains the following steps in sequence: Step 1: coating a support layer on the base film, and then washing and removing water; Step 2, coating solution A on the base film treated in step 1; Step 3, coating the base film prepared in step 2 with solution B; Step 4: solidifying, rinsing, and drying the membrane obtained in step 3 to obtain the reverse osmosis membrane.

5. The method for preparing a reverse osmosis membrane element according to claim 1, wherein The following steps are included in sequence: Step 1: stack the cut rectangular reverse osmosis membrane, water production diversion net, and reverse osmosis membrane from top to bottom, and seal the three sides to form a reverse osmosis membrane bag unit; Step 2: stack several water inlet screens and reverse osmosis membrane bag units in sequence, roll them around the central tube and fix them; Step 3: Based on the above step 2, the outer shell is further packaged to produce the reverse osmosis membrane element.

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