WO2022032731A1

WO2022032731A1 - Spiral-wound membrane element having scale inhibition function

Info

Publication number: WO2022032731A1
Application number: PCT/CN2020/111594
Authority: WO
Inventors: 武少禹; 刘星
Original assignee: 南京水联天下海水淡化技术研究院有限公司; 南京水杯子科技股份有限公司; 南京帝膜净水材料开发有限公司; 安徽昂可特膜科技有限公司
Priority date: 2020-08-12
Filing date: 2020-08-27
Publication date: 2022-02-17
Also published as: CN111825224A

Abstract

A spiral-wound membrane element having a scale inhibition function. The spiral-wound membrane element comprises a water production central tube (1) and at least one water purification membrane group wound around the water production central tube (1). The water purification membrane group sequentially comprises, from inside to outside, a water production flow guide mesh (2), a first separation membrane (3), a raw water flow guide mesh (4) and a second separation membrane (5). The raw water flow guide mesh (4) comprises a metal thin membrane (6), and plastic coarse fiber meshes or alloy metal wire meshes (7) arranged on two surfaces of the metal thin membrane (6). The water production central tube (1) is hollow, one end of the water production central tube being open, the other end of the water production central tube being closed, a group of water-passing holes (8) being provided in a tube wall of the water production central tube, and the water-passing holes (8) being in communication with the water production flow guide mesh (2). The raw water flow guide mesh (4) of the membrane element is composed of the scale inhibition alloy metal thin membrane (6) and the plastic coarse fiber meshes or alloy metal wire meshes (7), which are located on the surfaces of two sides of the metal thin membrane (6) and plated with scale inhibition alloys. Due to the scale inhibition and bacteriostasis functions of alloy metals, scaling on the surface of a membrane does not easily occur when raw water with a high hardness is treated by means of the membrane element, thereby prolonging the service life of the membrane.

Description

A roll-type membrane element with scale-inhibiting function

technical field

The invention relates to a roll-type membrane element in the field of water treatment membranes.

Background technique

Due to the increasing water pollution, people's demand for drinking water quality has increased, and a large number of reverse osmosis and nanofiltration water purification equipment have appeared on the market. Causes the attenuation of membrane water flux, among which water hardness, microorganisms and colloids pollute the surface of the membrane the most common. Therefore, how to improve the resistance to such pollution of reverse osmosis or nanofiltration membrane elements has become one of the focus of research and development in the industry.

Usually, modification of the membrane surface, and special diversion design can improve the fouling resistance of the membrane.

Surface modification methods usually include surface coating, surface graft modification and surface chemical synthesis modification. The surface coating modification method generally refers to the direct coating of a polymer material or surfactant on the surface of the membrane. During the coating process, new chemical bonds are generally not formed with the surface of the membrane, and the chemical structure of the surface of the membrane is not destroyed. , Mainly through physical action, such as van der Waals force or electrostatic force between molecules, the surface modifier is attached to the membrane surface, thereby forming a protective layer, improving the membrane surface potential, roughness or hydrophilicity.

In the spiral wound membrane element used in the reverse osmosis element, the number, length, width of the membrane leaves, the thickness and geometric structure of the raw water and the net water diversion grid have a certain influence on the fouling of the membrane, among which the raw water diversion The different designs of the grids have a great influence on the mass transfer behavior and pressure loss of the raw water, and thus have a great influence on the membrane fouling capacity accordingly.

However, with the improvement of living standards and the improvement of people's demand for drinking water quality, the pollution resistance performance of the current roll membrane elements in the field of water treatment membranes still cannot meet the demand.

SUMMARY OF THE INVENTION

Purpose of the invention: The purpose of the present invention is to provide a roll-type membrane element and the material and structure of the raw water guide net to improve the anti-scaling performance of the membrane element, which is especially suitable for the application of high-hardness wastewater environment.

Technical solutions:

The present invention provides a roll-type membrane element with a scale-inhibiting function, comprising a water-producing central pipe (1) and at least one group of water-purifying membrane sheets wound on the water-producing central pipe; The inside and outside sequentially include a produced water diversion net (2), a first separation membrane (3), a raw water diversion net (4), and a second separation membrane (5); the raw water diversion net (4) comprises metal The film sheet (6), and the plastic coarse fiber mesh or alloy wire mesh (7) arranged on both surfaces of the metal film sheet; the water production center pipe (1) is hollow, one end is open, the other end is closed, and the pipe A group of water passage holes (8) are arranged on the wall, and the water passage holes (8) are communicated with the produced water diversion net (2).

As an improvement, the plastic coarse fiber mesh or alloy metal wire mesh (7) distributed on both sides of the metal film sheet (6) of the raw water guiding net (4) is distributed at an angle of 20-160 degrees with the central pipe; the plastic coarse fiber The spacing between the mesh or alloy wire mesh (7) is 0.2-5mm.

As another improvement, the diameter of the plastic coarse fiber mesh or alloy wire mesh (7) is 0.1-0.7 mm, and the thickness of the metal film sheet (6) is 5-200 microns.

As another improvement, the metal thin film sheet (6) is made of the following parts by weight: 34-70 parts of copper, 2-30 parts of zinc, 10-25 parts of nickel, 2-5 parts of tin, and 3-10 parts of iron .

As another improvement, the first separation membrane (3) and the second separation membrane (5) are independently reverse osmosis membranes, nanofiltration membranes or ultrafiltration membranes.

As another improvement, a sealing ring is provided at the contact point between the water passage hole (8) and the produced water diversion net (2).

As another improvement, the plastic coarse fiber web is a plastic coarse fiber web with a scale-inhibiting alloy coating on the surface, and the coating is prepared by the following method: soak the plastic coarse fiber web with IPA solution for 1 hour and then rinse it repeatedly with IPA Three times, drying; then soaked in an aqueous solution containing 4.0wt% potassium dichromate and 3.0wt% sulfuric acid for 1 hour, rinsed three times with pure water; then soaked in an aqueous solution containing 0.3wt% SnCl2 and 2.5wt% hydrochloric acid for 2min, take out After immersion in an aqueous solution containing 0.1wt% PdCl2 and 1.0wt% hydrochloric acid for 10 minutes, rinsed with pure water three times to complete the surface activation of the fiber web; immerse the activated plastic coarse fiber web into the electroless plating solution for 5-10 minutes, pass Controlling the deposition time, metal Cu of about 0.2-1 micron is uniformly plated on the surface of the PP fiber web; wherein, the electroless plating solution is composed of: 0.7wt% CuSO4, 2.5wt% potassium sodium tartrate, 0.4wt% sodium hydroxide and 0.4wt% formaldehyde, the balance is water.

Beneficial effect: The roll-type membrane element provided by the present invention is composed of a scale-inhibiting alloy metal film sheet, and a plastic coarse fiber mesh or alloy wire mesh coated with scale-inhibiting alloy on both surfaces of the metal film sheet. And the antibacterial function makes the membrane element not easy to scale on the membrane surface when processing raw water with high hardness, which improves the service life of the membrane.

Description of drawings

Figure 1 is a schematic structural diagram of a rolled membrane element with anti-scaling function (partially unfolded);

Figure 2 is a schematic diagram of the combined structure of the raw water diversion net;

detailed description

Example:

A roll-type membrane element with a scale-inhibiting function, comprising a water-producing central pipe (1) and at least one group of water-purifying membrane sheets wound on the water-producing central pipe; A diversion net (2), a first separation membrane (3), a raw water diversion net (4), and a second separation membrane (5); the raw water diversion net (4) includes a metal film sheet (6), And the plastic thick fiber mesh or alloy metal wire mesh (7) arranged on both surfaces of the metal film sheet; the water production center pipe (1) is hollow, one end is open, the other end is closed, and a group of pipes are arranged on the pipe wall. The water hole (8) is communicated with the produced water diversion network (2). A sealing ring is provided at the contact between the water passage hole (8) and the produced water diversion net (2).

The first separation membrane (3) and the second separation membrane (5) are both reverse osmosis membranes.

The plastic thick fiber net is a plastic thick fiber net with a scale-inhibiting alloy coating on the surface, and the coating is prepared by the following method: soak the plastic thick fiber net with IPA solution for 1 hour, then rinse it with IPA repeatedly for three times, and dry it; Soak in an aqueous solution containing 4.0wt% potassium dichromate and 3.0wt% sulfuric acid for 1 hour, rinse with pure water for three times; then infiltrate into an aqueous solution containing 0.3wt% SnCl2 and 2.5wt% hydrochloric acid for 2min, take it out and immerse it in 0.1wt% hydrochloric acid %PdCl2 and 1.0wt% hydrochloric acid solution for 10 minutes, rinsed with pure water three times to complete the surface activation of the fiber web; immerse the activated plastic coarse fiber web into the electroless plating solution for 5-10 minutes, and by controlling the deposition time, about 0.2-1 micron metal Cu is uniformly plated on the surface of the PP fiber mesh; wherein, the electroless plating solution is composed of: 0.7wt% CuSO4, 2.5wt% potassium sodium tartrate, 0.4wt% sodium hydroxide and 0.4wt% formaldehyde, the rest The amount is water.

The following parameters can all realize the purpose of the present invention:

The plastic coarse fiber mesh or alloy metal wire mesh (7) distributed on both sides of the metal film sheet (6) of the raw water guiding net (4) is distributed at an angle of 20-160 degrees with the central pipe; the plastic coarse fiber mesh or alloy The spacing between the wire meshes (7) is 0.2-5mm.

The diameter of the plastic coarse fiber mesh or alloy metal wire mesh (7) is 0.1-0.7 mm, and the thickness of the metal film sheet (6) is 5-200 microns.

The metal thin film sheet (6) is made of the following parts by weight: 34-70 parts of copper, 2-30 parts of zinc, 10-25 parts of nickel, 2-5 parts of tin, and 3-10 parts of iron.

The first separation membrane (3) and the second separation membrane (5) are independently reverse osmosis membranes, nanofiltration membranes or ultrafiltration membranes.

A batch of rolled membrane elements with anti-scaling function were prepared and their performance was tested. The parameters of rolled membrane elements with anti-scaling function are shown in Table 1:

Test conditions:

Take 6 reverse osmosis membranes with a membrane area of 32cmx106cm and roll them into standard 3013 membrane elements. Test pressure: 0.8Mpa; recovery rate: 90%; test temperature: 25C. The concentration of each component of the original aqueous solution used in the test is as follows: 2000ppm CaCl2, 2000ppm NaHCO3, 10ppm milk powder, 1000ppm NaCl aqueous solution. Collect water flux and TDS values of raw water and purified water every 1 hour, and calculate the desalination rate and the attenuation percentage of water flux to characterize the scale inhibition ability of membrane elements. The smaller the water flux attenuation percentage, the stronger the scale inhibition ability.

Comparative example: six pieces of general-purpose PP mesh 32X55cm, diameter 0.5mm, and spacing 0.3mm were selected for the raw water mesh. Six 32cmx106cm reverse osmosis membranes are folded in half, and the six raw water nets are inserted between the folded membranes to make a rolled membrane element. The water flux and desalination rate were tested using the above conditions.

Test Example 1: The raw water mesh group includes an alloy film sheet with a thickness of about 50 microns and a raw water mesh with a thickness of 0.25 mm on both sides. Similarly, 6 groups of raw water network groups and reverse osmosis membranes of the same area were selected, and the others were the same as those in the comparative example. The test conditions were the same as in the comparative example.

Embodiment 2-12: select different raw water net groups for use, and concrete raw water net group constitutions and test results are shown in Table 1.

It can be seen from the results of the examples and comparative examples that the raw water reticulation group of the present invention improves the anti-scaling performance of the membrane to varying degrees. A proper proportion of alloy metal sheets plays a greater role in the raw water mesh group than the alloy wire mesh itself.

Table 1 list of comparative examples and examples

The above specific embodiments further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

A roll-type membrane element with scale-inhibiting function, characterized in that it comprises a water-producing central pipe (1) and at least one group of water-purifying membrane sheets wound on the water-producing central pipe; The inside and outside sequentially include a produced water diversion net (2), a first separation membrane (3), a raw water diversion net (4), and a second separation membrane (5); the raw water diversion net (4) comprises metal The film sheet (6), and the plastic coarse fiber mesh or alloy wire mesh (7) arranged on both surfaces of the metal film sheet; the water production center pipe (1) is hollow, one end is open, the other end is closed, and the pipe A group of water passage holes (8) are arranged on the wall, and the water passage holes (8) are communicated with the produced water diversion net (2).
A roll-type membrane element with anti-scaling function according to claim 1, characterized in that: plastic coarse fiber nets or alloy metal wires distributed on both sides of the metal film sheet (6) of the raw water guiding net (4) The net (7) and the central tube are distributed at an angle of 20-160 degrees; the distance between the plastic coarse fiber nets or alloy metal wire nets (7) is 0.2-5mm.
A roll-type membrane element with scale-inhibiting function according to claim 1, characterized in that: the diameter of the plastic coarse fiber mesh or alloy metal wire mesh (7) is 0.1-0.7 mm, and the metal film sheet (6) is 0.1-0.7 mm in diameter. ) thickness is 5-200 microns.
A roll-type membrane element with scale inhibition function according to claim 1, characterized in that: the metal thin film sheet (6) is made of the following parts by weight: 34-70 parts of copper, 2-30 parts of zinc, 10-25 parts of nickel, 2-5 parts of tin, 3-10 parts of iron.
A roll-type membrane element with scale inhibition function according to claim 1, characterized in that: the first separation membrane (3) and the second separation membrane (5) are independently reverse osmosis membranes, Nanofiltration or ultrafiltration membranes.
A roll-type membrane element with a scale-inhibiting function according to claim 1, characterized in that a sealing ring is provided at the contact point between the water passage hole (8) and the produced water diversion net (2).
A roll-type membrane element with scale-inhibiting function according to claim 1, characterized in that: the plastic coarse fiber net is a plastic coarse fiber net with a scale-inhibiting alloy coating on the surface, and the coating is obtained by the following method: The plastic crude fiber web was soaked in IPA solution for 1 hour, then rinsed three times with IPA, and dried; then soaked in an aqueous solution containing 4.0 wt % potassium dichromate and 3.0 wt % sulfuric acid for 1 hour, and rinsed with pure water three times; Put it into an aqueous solution containing 0.3wt% SnCl2 and 2.5wt% hydrochloric acid for 2 minutes, take it out and immerse it in an aqueous solution containing 0.1wt% PdCl2 and 1.0wt% hydrochloric acid for 10 minutes, rinse with pure water three times to complete the surface activation of the fiber web; The plastic coarse fiber web is immersed in the electroless plating solution for 5-10 minutes, and by controlling the deposition time, metal Cu of about 0.2-1 micron is uniformly plated on the surface of the PP fiber web; wherein, the composition of the electroless plating solution is: 0.7wt% CuSO4, 2.5wt% potassium sodium tartrate, 0.4wt% sodium hydroxide and 0.4wt% formaldehyde, and the balance is water.