Preparation method of multi-layer graphene oxide modified separation membrane

Abstract

The invention discloses a preparation method of a multilayer graphene oxide modified separation membrane. The preparation method comprises the following steps: preparing a dopamine solution by using a tris (hydroxymethyl) aminomethane hydrochloride solution; cutting a polyethersulfone film, putting the cut polyethersulfone film into a dopamine solution, and carrying out co-deposition operation; after codeposition is completed, taking out the polyethersulfone film, performing interfacial polymerization on the polyethersulfone film by using a 1, 3, 5-trimesoyl chloride solution, and preparing a graphene oxide / tannic acid mixed solution and a ferric chloride solution; putting the polyethersulfone membrane subjected to interfacial polymerization into a graphene oxide / tannic acid mixed solution for co-deposition, taking out the polyethersulfone membrane, and putting the polyethersulfone membrane into a ferric chloride solution for cross-linking; the codeposition-crosslinking operation is repeated twice, then the polyether sulfone membrane is taken out and dried, and the multi-layer graphene oxide modified separation membrane is obtained.The multi-layer graphene oxide modified separation membrane is reasonable in structure, the polyamide layer not prone to falling off is prepared through the adhesiveness of dopamine, then graphene oxide is codeposited multiple times, the membrane aperture is further reduced, and the hydrophilicity of the membrane is further improved.

Description

Technical Field

[0001] The invention relates to the field of separation membranes, and in particular to a method for preparing a multilayer graphene oxide modified separation membrane. Background Art

[0002] With the rapid growth of population and the development of industrial and agricultural activities, the global water crisis caused by water shortage and water pollution has become a serious global problem. The use of science and technology has become a key way to solve the water crisis problem, among which membrane water treatment technology has been rapidly developed and applied.

[0003] At present, aromatic polyamide TFC membranes are widely used in water treatment technology. They are usually obtained by interfacial polymerization of aqueous phase monomers and organic phase monomers on porous base membranes. The excellent performance of TFC membranes in water flux and salt removal makes it the most widely used membrane. Increasing the hydrophilicity of the membrane surface is considered to be an effective way to increase membrane flux. Mussel-inspired dopamine (DA) can self-polymerize in aqueous solution to form polydopamine (PDA). More importantly, PDA contains hydrophilic groups such as amino and hydroxyl groups, which can improve the hydrophilicity of the membrane surface. Graphene oxide contains rich oxygen-containing functional groups and has nano-transport channels, which can further improve the hydrophilicity of the membrane surface.

[0004] In summary, how to improve the hydrophilicity of the membrane surface and thus enhance the performance of the separation membrane is a problem that needs to be researched and developed at this stage. In view of the above problems, a solution is proposed below. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a multilayer graphene oxide modified separation membrane, the experimental operation is simple, and the performance of the membrane is effectively improved.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions: A method for preparing a multilayer graphene oxide modified separation membrane comprises the following steps: S1, dissolving dopamine in a pH 8.5 tris(hydroxymethyl)aminomethane hydrochloride) solution to accelerate the self-polymerization of dopamine to obtain polydopamine; S2. Cut the polyethersulfone membrane into squares and stick them on a smooth glass plate for later use; S3, placing the polyethersulfone membrane in an enamel dish, pouring in the dopamine solution, placing the enamel dish in a shaker, shaking at a constant speed, and uniformly depositing to complete the co-deposition operation; S4. After the co-deposition is completed, the polyethersulfone membrane is taken out from the dopamine solution and placed in water for standby use; S5, using n-hexane as a solvent to prepare a 1,3,5-trimethylbenzenecarboxylic acid chloride solution; S6, interfacial polymerization is performed on the polyethersulfone membrane, the polyethersulfone membrane is taken out from the water, and the membrane is spread flat, the water on the membrane surface is wiped dry with paper, and the membrane is clamped with a polytetrafluoroethylene plate, and 1,3,5-trimethylbenzenecarboxylic acid chloride solution is poured into it for reaction, and after the reaction is completed, the remaining 1,3,5-trimethylbenzenecarboxylic acid chloride solution is poured out, and the polyethersulfone membrane is taken out and put into water for standby use; S7, preparing a graphene oxide / tannic acid mixed solution and a ferric chloride solution; S8, placing the polyethersulfone membrane after interfacial polymerization into a graphene oxide / tannic acid mixed solution for co-deposition, taking it out and placing it into a ferric chloride solution for cross-linking; S9. Repeat the operation of S8 twice. After completion, take out the polyethersulfone membrane and dry it to obtain a multi-layer graphene oxide modified separation membrane.

[0007] Preferably, in S1, the concentration of dopamine in the dopamine solution is 2 g / L.

[0008] Preferably, in S2, the pore size of the polyethersulfone membrane is micropore, and the pore size of the polyethersulfone membrane is 0.1 micrometer.

[0009] Preferably, in S3, the shaking table temperature is set to 40°C, the shaking rate is 50 rpm, and the co-deposition time is 6-12 h.

[0010] Preferably, in S5, the concentration of 1,3,5-trimethylbenzenecarboxylic acid chloride solution is 0.1%wt.

[0011] Preferably, in S6, the interfacial polymerization reaction time is 3-7 min.

[0012] Preferably, in S7, the concentration of graphene oxide in the graphene oxide / tannic acid mixed solution is 1 g / L, the concentration of tannic acid mixed solution is 4 g / L, and the concentration of ferric chloride in the ferric chloride solution is 5 g / L.

[0013] Preferably, in S8, the co-deposition time in the graphene oxide / tannic acid mixed solution is 5-20 min, and the cross-linking time in the ferric chloride solution is 10-30 min.

[0014] Preferably, in S9, the drying temperature is 60° C. and the drying time is 12 hours.

[0015] The beneficial effects of the present invention are: (1) The present invention utilizes the adhesion of dopamine to prepare a polyamide layer that is not easy to fall off, thereby reducing the pore size of the membrane and improving the hydrophilicity of the membrane surface.

[0016] (2) The present invention utilizes the cross-linking effect of tannic acid and ferric chloride to co-deposit a graphene oxide layer on the surface of the membrane to form a hydrophilic layer, thereby effectively improving the hydrophilicity and retention rate of the membrane.

[0017] The present invention effectively compensates for the defects of the polyamide layer through the graphene oxide layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The surface morphologies of the original PES membrane, the membrane after interfacial polymerization, and the membrane after co-deposition of graphene oxide in Example 1 are shown.

[0019] Figure 2 Surface contact angles of the original PES film, the film after interfacial polymerization, and the film after co-deposition of graphene oxide. DETAILED DESCRIPTION

[0020] The following is only a preferred embodiment of the present invention, and the protection scope is not limited to this embodiment. All technical solutions under the concept of the present invention should belong to the protection scope of the present invention.

[0021] The preparation of a graphene oxide modified membrane in this embodiment includes the preparation of a polyamide layer and a graphene oxide layer.

[0022] The preparation method comprises the following steps: S1. Dissolve DA in tris(hydroxymethylaminomethane) hydrochloride solution (Tris solution) to prepare a 0.2 g / L solution.

[0023] S2. Stick the double-sided tape on both sides of the glass plate and stick the PES film evenly on the glass plate.

[0024] S3. Set the shaking table temperature to 40 °C and the shaking rate to 50 rpm. After co-sedimentation for 12 hours, take out and put into clean water.

[0025] S5. Prepare TMC solution with a concentration of 0.1% wt.

[0026] S6. The interfacial polymerization reaction time is 5 min.

[0027] The concentrations of S7 and GO were 1 g / L, the concentration of TA was 4 g / L, and the concentration of FeCl3 was 5 g / L.

[0028] S8. The co-deposition time in GO / TA solution is 5 min, the FeCl3 cross-linking time is 10 min, and the above steps are repeated twice.

[0029] S9. Place the co-deposited film in a 60°C oven for 12 hours.

[0030] The contact angle of the membrane surface obtained is 68.8°, and the retention rate can reach 70% when using MgSO4 for salt rejection experiment.

[0031] The preparation of a graphene oxide modified membrane in this embodiment includes the preparation of a polyamide layer and a graphene oxide layer.

[0032] S1. Dissolve DA in Tris solution to prepare a 0.2 g / L solution.

[0033] S2. Stick the double-sided tape on both sides of the glass plate and stick the PES film evenly on the glass plate.

[0034] S3. Set the shaking table temperature to 40 °C and the shaking rate to 50 rpm. After 24 hours of co-sedimentation, take out and put into clean water.

[0035] S5. Prepare TMC solution with a concentration of 0.1% wt.

[0036] S6. The interfacial polymerization reaction time is 10 min.

[0037] The concentrations of S7 and GO were 1 g / L, the concentration of TA was 4 g / L, and the concentration of FeCl3 was 5 g / L.

[0038] S8. The co-deposition time in GO / TA solution was 10 min, the FeCl3 cross-linking time was 10 min, and the above steps were repeated twice.

[0039] S9. Place the co-deposited film in a 60°C oven for 12 hours.

[0040] The contact angle of the membrane surface was 65.6°, and the salt rejection experiment was carried out using MgSO4, and the rejection rate could reach 75%.

[0041] The preparation of a graphene oxide modified membrane in this embodiment includes the preparation of a polyamide layer and a graphene oxide layer.

[0042] S1. Dissolve DA in Tris solution to prepare a 0.2 g / L solution.

[0043] S2. Stick the double-sided tape on both sides of the glass plate and stick the PES film evenly on the glass plate.

[0044] S3. Set the shaking table temperature to 40 °C and the shaking rate to 50 rpm. After 48 h of co-sedimentation, take out and put into clean water.

[0045] S5. Prepare TMC solution with a concentration of 0.1% wt.

[0046] S6. The interfacial polymerization reaction time is 20 min.

[0047] The concentrations of S7 and GO were 1 g / L, the concentration of TA was 4 g / L, and the concentration of FeCl3 was 5 g / L.

[0048] S8. The co-deposition time in GO / TA solution was 20 min, the FeCl3 cross-linking time was 30 min, and the above steps were repeated twice.

[0049] S9. Place the co-deposited film in a 60°C oven for 12 hours.

[0050] The obtained membrane surface contact angle is 62.35°, and the salt rejection experiment using MgSO4 shows a rejection rate of 80%.

[0051] The specific embodiments described above further illustrate the technical problems, technical solutions and beneficial effects solved by the present invention. 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 modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a multilayer graphene oxide modified separation membrane, characterized in that: The steps include: S1, dissolving dopamine in a pH 8.5 tris(hydroxymethyl)aminomethane hydrochloride) solution to accelerate the self-polymerization of dopamine to obtain polydopamine; S2. Cut the polyethersulfone membrane into squares and stick them on a smooth glass plate for later use; S3, placing the polyethersulfone membrane in an enamel dish, pouring in the dopamine solution, placing the enamel dish in a shaker, shaking at a constant speed, and uniformly depositing to complete the co-deposition operation; S4. After the co-deposition is completed, the polyethersulfone membrane is taken out from the dopamine solution and placed in water for standby use; S5, using n-hexane as a solvent to prepare a 1,3,5-trimethylbenzenecarboxylic acid chloride solution; S6, interfacial polymerization is performed on the polyethersulfone membrane, the polyethersulfone membrane is taken out from the water, and the membrane is spread flat, the water on the membrane surface is wiped dry with paper, and the membrane is clamped with a polytetrafluoroethylene plate, and 1,3,5-trimethylbenzenecarboxylic acid chloride solution is poured into it for reaction, and after the reaction is completed, the remaining 1,3,5-trimethylbenzenecarboxylic acid chloride solution is poured out, and the polyethersulfone membrane is taken out and put into water for standby use; S7, preparing a graphene oxide / tannic acid mixed solution and a ferric chloride solution; S8, placing the polyethersulfone membrane after interfacial polymerization into a graphene oxide / tannic acid mixed solution for co-deposition, taking it out and placing it into a ferric chloride solution for cross-linking; S9. Repeat the operation of S8 twice. After completion, take out the polyethersulfone membrane and dry it to obtain a multi-layer graphene oxide modified separation membrane.

2. The method for preparing a multilayer graphene oxide modified separation membrane according to claim 1, characterized in that: In S1, the concentration of dopamine in the dopamine solution is 2 g / L.

3. The method for preparing a multilayer graphene oxide modified separation membrane according to claim 1, characterized in that: In the S2, the pore size of the polyethersulfone membrane is micropore, and the pore size of the polyethersulfone membrane is 0.1 micrometer.

4. The method for preparing a multilayer graphene oxide modified separation membrane according to claim 1, characterized in that: In S3, the shaking table temperature is set to 40° C., the shaking rate is 50 rpm, and the co-deposition time is 6-12 h.

5. The method for preparing a multilayer graphene oxide modified separation membrane according to claim 1, characterized in that: In the S5, the concentration of 1,3,5-trimethylbenzenecarboxylic acid chloride solution is 0.1%wt.

6. The method for preparing a multilayer graphene oxide modified separation membrane according to claim 1, characterized in that: In the step S6, the interfacial polymerization reaction time is 3-7 min.

7. The method for preparing a multilayer graphene oxide modified separation membrane according to claim 1, characterized in that: In S7, the concentration of graphene oxide in the graphene oxide / tannic acid mixed solution is 1 g / L, the concentration of tannic acid mixed solution is 4 g / L, and the concentration of ferric chloride in the ferric chloride solution is 5 g / L.

8. The method for preparing a multilayer graphene oxide modified separation membrane according to claim 1, characterized in that: In S8, the co-deposition time in the graphene oxide / tannic acid mixed solution is 5-20 minutes, and the cross-linking time in the ferric chloride solution is 10-30 minutes.

9. The method for preparing a multilayer graphene oxide modified separation membrane according to claim 1, characterized in that: In S9, the drying temperature is 60° C. and the drying time is 12 hours.

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