Composite separation membrane slurry and preparation method thereof, reverse osmosis composite membrane and application thereof

Abstract

The present invention discloses a composite separation membrane slurry and its preparation method, a reverse osmosis composite membrane and its application, including: dispersing SiO2 particles and a surfactant in water and then mixing them to obtain a SiO2 dispersion; uniformly dispersing MoS2 particles in the SiO2 dispersion to obtain a silicon-molybdenum mixed solution; grinding the silicon-molybdenum mixed solution with a colloid mill until the particle size of MoS2 particles < 500 nm to obtain a silicon-molybdenum slurry; and finally filtering, washing and dispersing the silicon-molybdenum slurry to obtain a composite separation membrane slurry. By using a colloid mill and utilizing the extrusion and friction forces between particles, the present invention exfoliates MoS2 into a porous flaky structure. The reverse osmosis composite membrane prepared therefrom has a large flux, a high desalination rate, controllable pore size, and good hydrophilicity, which is beneficial to reducing the desalination pressure, and can be applied to fields such as seawater desalination, saline-alkali water desalination, and desalination treatment of sewage.

Description

Technical Field

[0001] The present invention relates to the technical field of separation membranes, and more specifically, to a composite separation membrane slurry and a preparation method thereof, a reverse osmosis composite membrane and applications thereof. Background Art

[0002] Fresh water is a necessity for human life and an important raw material for industrial and agricultural production. The imbalance between fresh water demand and availability in time and space has led to a global shortage of fresh water resources, especially in coastal cities, small islands and some inland areas.

[0003] Membrane separation can be used to separate fresh water from seawater or saline water. It has the advantages of high efficiency and energy saving and has attracted widespread attention. 2 ) The separation membrane has excellent desalination performance, and water passes through MoS 2 The defects on MoS 2 The defect size limits the passage of salt ions, which can reduce the energy consumption and cost of traditional reverse osmosis (RO) membrane desalination and alleviate the problem of calcium scaling on the membrane surface to a certain extent.

[0004] But MoS 2 The pore size of the separation membrane is difficult to control. If the pore size is too small, water molecules cannot pass through. If the pore size is too large, the salt separation effect will be poor. 2 The water flux of the monolayer membrane increases with the increase of pore diameter, but the ion retention rate of the large pores is very low. When the pore diameter is 0.74 nm, the water flux of the monolayer MoS 2 The membrane has excellent water permeability and desalination performance, and its water permeability is 2 to 5 orders of magnitude greater than that of commercial RO membrane materials.

[0005] However, most current research is at the stage of theoretical verification and small-scale experiments. There are still some major technical difficulties in turning it into an application stage, including (1) it is difficult to prepare large-area single-layer MoS 2 Thin films; (2) It is difficult to generate nanopores with controllable size and type in the membrane; (3) In addition, MoS 2 The hydrophilicity of the material is poor, although the theoretical model verifies that MoS 2 The defects of the membrane have very excellent hydrophilic properties, but the overall membrane material still cannot avoid the increase in water permeability pressure caused by hydrophobicity. Summary of the invention

[0006] It is difficult to prepare large-area single-layer MoS 2 Thin film, and MoS 2 The difficulty in controlling the nanopore size of the separation membrane and the poor hydrophilicity lead to the 2The separation membrane has low desalination rate and high desalination pressure. The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a composite separation membrane slurry and a preparation method thereof, a reverse osmosis composite membrane and its application. 2 Particles and SiO 2 After the particles are blended, they are ground by colloid mill to form SiO 2 Nanoparticles and MoS 2 The particles squeeze and rub against each other, increasing the MoS 2 defects and MoS 2 The membrane is peeled into a sheet structure to improve the water permeability and mechanical strength. In addition, MoS 2 The compound contains a certain amount of hydrophilic SiO 2 , to improve MoS 2 The hydrophilicity of the separation membrane reduces the desalination pressure and the energy consumption of salt / water separation.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A method for preparing a composite separation membrane slurry comprises the following steps:

[0009] (1) SiO 2 The particles are dispersed in water and mixed with a surfactant to obtain SiO 2 dispersion, wherein the SiO 2 In the dispersion, SiO 2 The mass ratio of particles to surfactant is 100:(1~5);

[0010] (2) MoS 2 Particles added to the SiO 2 The dispersion is mixed to make MoS 2 The particles are evenly dispersed in SiO 2 dispersion to obtain a silicon-molybdenum mixed solution, wherein in the silicon-molybdenum mixed solution, MoS 2 The mass of the particles accounts for 5% to 30% of the total mass of the silicon-molybdenum mixed solution. 2 The mass of the particles accounts for 1% to 20% of the total mass of the silicon-molybdenum mixture;

[0011] (3) Grinding the silicon-molybdenum mixed solution in a colloid mill at a rotation speed of 1000 r / min to 8000 r / min, the feeding rate of the silicon-molybdenum mixed solution is 0.1 L / h to 10 L / h, the grinding temperature is 10° C. to 60° C., the gap between the rotor and the stator of the colloid mill is 0.1 mm to 0.5 mm, and the grinding times are 1 to 6 times, until the MoS 2The particles are flaky particles with an average particle size of less than 500 nm, and silicon-molybdenum slurry is obtained. The silicon-molybdenum slurry is then filtered, cleaned and dispersed to obtain a composite separation membrane slurry.

[0012] Optionally, in step (3), the preferred rotation speed is 3000 r / min~8000 r / min, the preferred feed rate of the silicon-molybdenum mixed solution is 0.1 L / h~5 L / h, the preferred grinding temperature is 30°C~50°C, and the gap between the colloid mill rotor and the stator is preferably 0.1 mm~0.3 mm.

[0013] Optionally, the SiO 2 In the dispersion, SiO 2 The preferred mass ratio of particles to surfactant is 100:(3~5).

[0014] Optionally, in step (1), the surfactant includes at least one of sodium dodecyl sulfate, Span 60, phenyl tris(trimethylsiloxy) silane and octyl polytrimethylsiloxane. Preferably, the surfactant includes sodium dodecyl sulfate and phenyl tris(trimethylsiloxy) silane in a mass ratio of 2:8.

[0015] Optionally, in step (2), the MoS 2 The particles are spherical particles or quasi-spherical powder particles obtained by screening.

[0016] Optionally, the MoS 2 The particle size is 100nm~2000nm.

[0017] Optionally, the MoS 2 The particle size of the particles includes, but is not limited to, 100 nm, 500 nm, 900 nm, 1000 nm, 1100 nm, 1500 nm, 1900 nm, and 2000 nm.

[0018] Optionally, in step (1), the SiO 2 The particles are spherical particles or quasi-spherical powder particles obtained by screening.

[0019] Optionally, the SiO 2 The particle size is 5nm~80nm.

[0020] Optionally, the SiO 2 The particle size of the particles includes, but is not limited to, 5 nm, 7 nm, 10 nm, 13 nm, 20 nm, 50 nm, 70 nm, and 80 nm.

[0021] Optionally, the method for preparing the composite separation membrane slurry also includes treating the silicon-molybdenum slurry: subjecting the silicon-molybdenum slurry to ultrasonic treatment for 0.5h~10h, filtering and cleaning, and then dispersing it in water to obtain a composite separation membrane slurry with a solid content of 60%~70%.

[0022] The invention also discloses a composite separation membrane slurry prepared by the above-mentioned preparation method.

[0023] The invention also discloses a reverse osmosis composite membrane. The reverse osmosis composite membrane is prepared by vacuum filtration based on the composite separation membrane slurry prepared by the above-mentioned preparation method.

[0024] The invention also discloses an application of the reverse osmosis composite membrane in seawater desalination, saline-alkali water desalination and sewage desalination.

[0025] Optionally, the application includes: utilizing a reverse osmosis membrane method and using the reverse osmosis composite membrane to achieve separation of salt and water.

[0026] Implementing the embodiments of the present invention will have the following beneficial effects:

[0027] In the embodiment of the present invention, MoS 2 Particles and silicon dioxide (SiO 2 The nanoparticles were blended and ground by colloid mill. The grinding speed, grinding time, grinding temperature and gap of the colloid mill were adjusted to control the SiO 2 Nanoparticles and MoS 2 The squeezing and friction between particles destroy the MoS 2 Particle structure, increase MoS 2 defects, making the prepared MoS 2 The defect morphology of MoS 2 The membrane is peeled off into a porous sheet structure to improve the water permeability and mechanical strength of the membrane, and to improve the membrane flux and desalination performance. In addition, SiO 2 The hydrophilicity of nanoparticles significantly improves the MoS 2 The hydrophilicity of the water reduces the desalination pressure, thereby significantly reducing the energy consumption of salt / water separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a preparation flow chart of the present invention.

[0029] Figure 2 This is a transmission electron microscope image of the composite separation membrane prepared in Example 1 of the present invention after slurry treatment. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited in any way.

[0031] Example 1

[0032] The method for preparing the composite separation membrane slurry of this embodiment comprises the following steps:

[0033] (1) SiO with a size of 7nm~13nm 2 After the spherical particles were dispersed in water, sodium dodecyl sulfate and phenyltris(trimethylsiloxy)silane were added in a mass ratio of 2:8 and mixed. 2 The mass ratio of particles to the total mass of surfactant was 100:5, and SiO 2 Dispersion.

[0034] (2) MoS with a size of 900nm~1100nm 2 Spherical particles are added to SiO 2 The dispersion is mixed to make MoS 2 The particles are evenly dispersed in SiO 2 The dispersion was mixed to obtain a mixture in which MoS 2 The mass of the particles accounts for 12% of the total mass of the mixed liquid. 2 The mass of the particles accounts for 10% of the total mass of the mixed liquid.

[0035] (3) The mixed solution was ground in a colloid mill at a rotation speed of 3000 r / min, the feed rate of the mixed solution was 2 L / h, the grinding temperature was controlled between 30°C and 35°C, the gap between the rotor and the stator of the colloid mill was 0.2 mm, and the grinding number was 5 times until MoS 2 The particles were flaky particles with a particle size of 200nm~500nm, and were treated with ultrasound for 2h, filtered, washed with water and ethanol three times respectively, and then dispersed in water to obtain a composite separation membrane slurry with a solid content of 62%, in which MoS 2 The flake size is 350±150nm.

[0036] Embodiment 2-7

[0037] Example 2-7 provides a method for preparing a composite separation membrane slurry. Compared with Example 1, the difference is that the grinding speed in step (3) is changed. Except for the above difference, other operations are the same and will not be repeated here. The grinding speeds in Examples 2-7 are 500 r / min, 1000 r / min, 2000 r / min, 5000 r / min, 8000 r / min, and 10000 r / min, respectively. Among them, the MoS in Examples 2-7 2The flake sizes are 850±200nm, 490±200nm, 450±150nm, 430±150nm, 130±80nm, and 110±80nm, respectively.

[0038] Examples 8-12

[0039] Examples 8-12 provide a method for preparing a composite separation membrane slurry. Compared with Example 1, the difference is that the feed rate of grinding in step (3) is changed. Except for the above differences, other operations are the same and will not be repeated here. The feed rates of grinding in Examples 8-12 are 0.05 L / h, 0.1 L / h, 5 L / h, 10 L / h and 20 L / h, respectively.

[0040] Examples 13-17

[0041] Examples 13-17 provide a method for preparing a composite separation membrane slurry. Compared with Example 1, the difference is that the gap of the colloid mill in step (3) is changed. Except for the above difference, other operations are the same and will not be repeated here. The gaps of the colloid mill in Examples 13-17 are 0.05 mm, 0.1 mm, 0.3 mm, 0.5 mm, and 0.8 mm, respectively.

[0042] Examples 18-19

[0043] Example 18-19 provides a method for preparing a composite separation membrane slurry. Compared with Example 1, the difference is that the MoS 2 The particle size of the particles is the same except for the above differences, which will not be described here. 2 The particle size of the particles is controlled to be 100nm~200nm, 500nm~800nm.

[0044] Examples 20-22

[0045] Example 20-22 provides a method for preparing a composite separation membrane slurry. Compared with Example 1, the difference is that the SiO 2 The particle size of spherical particles, except for the above differences, other operations are the same, which will not be repeated here, as follows:

[0046] In Example 20, SiO 2 The size of the spherical particles is 2nm~5nm.

[0047] In Example 21, SiO 2 The size of the spherical particles is 5nm~7nm.

[0048] In Example 22, SiO 2The size of the spherical particles is 40nm~80nm.

[0049] Among them, MoS in Example 22 2 The flake size is 50±3 nm.

[0050] Embodiment 23-24

[0051] Example 23-24 provides a method for preparing a composite separation membrane slurry. Compared with Example 1, the difference is that the MoS in step (2) is changed to 2 Particles and SiO 2 The mass of the particles accounts for the total mass of the mixed solution. Except for the above differences, other operations are the same and will not be repeated here. In Example 23, MoS 2 The particle mass ratio is 4%, SiO 2 The mass ratio of the particles is 0.5%; in Example 24, MoS 2 The particle mass ratio is 30%, SiO 2 The mass ratio of the particles is 1%.

[0052] Examples 25-28

[0053] Example 25-28 provides a method for preparing a composite separation membrane slurry. Compared with Example 1, the difference is that in step (1), SiO 2 The mass ratio of the particles to the total mass of the surfactant is the same except for the above differences, which will not be described here; in Examples 25-28, SiO 2 The mass ratios of particles to the total mass of surfactant were 100:0.5, 100:1, 100:3, and 100:8, respectively.

[0054] Embodiment 29

[0055] The difference between this embodiment and embodiment 1 is that this embodiment only uses sodium dodecyl sulfate, SiO 2 The mass ratio of the particles to sodium dodecyl sulfate is 100:5.

[0056] Embodiment 30

[0057] The difference between this embodiment and embodiment 1 is that the grinding process is performed three times. 2 The flake sizes were 250±150nm.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 1 is that no SiO 2 Spherical particles.

[0060] Comparative Example 2

[0061] The only difference between this comparative example and Example 1 is that sodium dodecyl sulfate and phenyltris(trimethylsiloxy)silane are not added.

[0062] Embodiment 31

[0063] A 3.5% mass fraction NaCl aqueous solution was used as a water source, and the reverse osmosis composite membrane prepared by Example 1-29 and Comparative Example 1-2 was desalinated. The preparation method of the reverse osmosis composite membrane was vacuum filtration. Specifically, 0.2 g of the composite membrane slurry was stirred and dispersed in 50 g of deionized water, and a vacuum filtration method was used to obtain an area of ​​40±1 cm 2 The reverse osmosis composite membrane has a thickness of 10-14 μm and a support layer of cellulose filter membrane with a pore size of 0.45 μm and a thickness of 0.12 mm. After the reverse osmosis composite membrane with the filter membrane is dried, a 2 cm pore area is pasted on the surface of the reverse osmosis composite membrane. 2 The strong tape was used to fix it on the filtration equipment, with the reverse osmosis composite membrane side facing upward to contact the water source to be treated. 300 mL of salt water source was taken for vacuum filtration. When the filtrate volume reached 100 mL, the filtration was stopped. The time taken for the filtrate to reach 100 mL was recorded, and the ionic conductivity of the filtrate was tested to calculate the salt concentration in the filtrate, as shown in Table 1.

[0064] Table 1 Salt / water separation performance results of Examples 1-30 and Comparative Examples 1-2

[0065]

[0066] Embodiment 32

[0067] Taking seawater as the water source, it was desalinated by the reverse osmosis composite membrane prepared by Examples 1-2, 22, 29-30 and Comparative Example 1-2. The method was the same as that of Example 31 and will not be described here. The salt concentration in the filtrate was calculated as shown in Table 2.

[0068] Table 2 Salt / water separation performance results of examples and comparative examples

[0069]

[0070] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a composite separation membrane slurry, characterized in that: The following steps are involved: (1) dispersing SiO2 particles and a surfactant in water and mixing them to obtain a SiO2 dispersion, wherein the mass ratio of SiO2 particles to the surfactant in the SiO2 dispersion is 100:(1-5); (2) adding MoS2 particles to the SiO2 dispersion and mixing them so that the MoS2 particles are uniformly dispersed in the SiO2 dispersion to obtain a silicon-molybdenum mixed solution, wherein the mass of the MoS2 particles in the silicon-molybdenum mixed solution accounts for 5% to 30% of the total mass of the silicon-molybdenum mixed solution, and the mass of the SiO2 particles accounts for 1% to 20% of the total mass of the silicon-molybdenum mixed solution; (3) Grinding the silicon-molybdenum mixed liquid in a colloid mill at a rotation speed of 1000 r / min~8000 r / min, the feed rate of the silicon-molybdenum mixed liquid is 0.1 L / h~10 L / h, the grinding temperature is 10°C~60°C, the gap between the rotor and the stator of the colloid mill is 0.1 mm~0.5 mm, and the number of grinding times is 1 time~6 times, until the MoS2 particles are flaky particles with an average particle size of less than 500 nm, to obtain silicon-molybdenum slurry, and then filtering, washing and dispersing the silicon-molybdenum slurry to obtain a composite separation membrane slurry.

2. The method for preparing the composite separation membrane slurry according to claim 1, characterized in that: In step (3), the rotation speed is 3000 r / min~8000 r / min, the feed rate of the silicon-molybdenum mixed solution is 0.1 L / h~5 L / h, the grinding temperature is 30°C~50°C, and the gap between the colloid mill rotor and the stator is 0.1 mm~0.3 mm.

3. The method for preparing the composite separation membrane slurry according to claim 1, characterized in that: In the SiO2 dispersion, the mass ratio of SiO2 particles to surfactant is 100:(3~5).

4. The method for preparing a composite separation membrane slurry according to claim 1, characterized in that: In step (1), the surfactant includes at least one of sodium dodecyl sulfate, Span 60, phenyl tris(trimethylsiloxy)silane and octyl polytrimethylsiloxane; In step (2), the MoS2 particles are spherical particles or quasi-spherical powder particles, and the particle size of the MoS2 particles is 100nm~2000nm; In step (1), the SiO2 particles are spherical particles or quasi-spherical powder particles, and the particle size of the SiO2 particles is 5nm~80nm.

5. The method for preparing a composite separation membrane slurry according to claim 1, characterized in that: The method for preparing the composite separation membrane slurry further comprises treating the silicon-molybdenum slurry: The silicon-molybdenum slurry is subjected to ultrasonic treatment for 0.5 h to 10 h, filtered, cleaned, and then dispersed in water to obtain a composite separation membrane slurry with a solid content of 60% to 70%.

6. A composite separation membrane slurry prepared by the preparation method according to any one of claims 1 to 5.

7. A reverse osmosis composite membrane, characterized in that: The reverse osmosis composite membrane is prepared by vacuum filtration of a composite separation membrane slurry prepared by the preparation method according to any one of claims 1 to 5.

8. Use of the reverse osmosis composite membrane as claimed in claim 7 in seawater desalination, saline-alkali water desalination and sewage desalination.

9. The use according to claim 8, characterized in that: The application includes: utilizing the reverse osmosis membrane method and using the reverse osmosis composite membrane to separate salt and water.

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