Preparation and application of small-aperture amination-polyamide roll type ultrafiltration membrane

Abstract

The invention belongs to the technical field of membranes, and discloses a preparation method and application of a small-aperture amination-polyamide roll type ultrafiltration membrane, a polyamide layer is subjected to amination treatment by using DETA (diethylenetriamine), the electronegativity of the surface of the membrane is changed by optimizing the concentration of DETA, the charge property of the surface of the membrane is optimized, and the electronegativity of the surface of the membrane is reduced, so that the ultrafiltration membrane is prepared. Therefore, the influence of the electrostatic repulsion effect on the rejection rate is reduced, and the separation performance of the membrane on small-molecular organic matters / inorganic salts is improved. The preparation method is simple to operate and low in cost. The prepared small-aperture amination-polyamide roll type ultrafiltration membrane can be used for recycling RO concentrated water in the field of printing and dyeing wastewater treatment and the application fields of purification and decoloration of macromolecules such as protein, polypeptide and drugs in the pharmaceutical industry.

Description

Technical Field

[0001] The present invention relates to the field of membrane technology, and more particularly to the preparation and application of a small-pore aminated polyamide rolled ultrafiltration membrane, which belongs to the field of environmental protection. Background Art

[0002] The reuse of printing and dyeing wastewater currently generally adopts the "physical and chemical + biochemical + ultrafiltration + reverse osmosis (RO)" treatment process. Among them, RO produced water is directly reused; RO concentrated water is discharged to the park sewage treatment plant for centralized treatment. After biochemical treatment, RO concentrated water still has problems of high COD and conductivity, which are difficult to treat. The main pollutants in RO concentrated water are mainly small molecular organic matter and inorganic salts. Direct discharge to the park sewage treatment plant is not conducive to biochemical treatment, and it also causes a waste of inorganic salts. On the other hand, in the dyeing process, inorganic salts (such as Na 2 SO 4 ) as a dyeing accelerator or dyeing retarder. The treatment of RO concentrated water has always been a difficult point in the reuse technology of printing and dyeing wastewater. Based on this, the project team developed a high-salt concentrated water direct reuse technology based on electrodialysis in the early stage. Its process is "RO concentrated water + spiral ultrafiltration + chelating resin + electrodialysis". The role of spiral ultrafiltration is to separate organic matter / inorganic salts. At present, the existing spiral ultrafiltration membrane has a general retention effect on small molecular organic matter, and the removal rate of COD and chromaticity in RO concentrated water is not ideal, and the removal effect needs to be improved. In addition, there are few reports on the research and application of improving the retention rate of spiral ultrafiltration membranes for small molecular organic matter at home and abroad. At present, only a few membrane product companies have mastered the preparation technology of spiral ultrafiltration membranes for separating small molecular organic matter / inorganic salts, such as NF8 of Zhongke Ruiyang and LCRNF of Meiyi. Summary of the invention

[0003] Aiming at the problem that the existing rolled ultrafiltration membrane has an unsatisfactory interception effect on small molecule organic matter, the present invention proposes to prepare a small pore size aminated-polyamide rolled ultrafiltration membrane, improve the interception rate of the rolled ultrafiltration membrane for small molecule organic matter, and at the same time reduce the influence of electrostatic repulsion on the interception rate, thereby improving the separation effect of COD / inorganic salts, thereby achieving the purpose of increasing the reuse rate of inorganic salts.

[0004] To achieve the above object, according to one embodiment of the present invention, a method for preparing a small-pore aminated-polyamide rolled ultrafiltration membrane is provided, and the preparation scheme comprises the following steps: S1: firstly preparing MPD aqueous solutions of different mass concentrations; S2: then preparing TMC oil solutions of different mass concentrations; S3: then preparing short linear amine solutions of different mass concentrations; S4: then blowing the PSf bottom membrane with an air gun, allowing the aqueous solution to contact the membrane surface for a period of time, then pouring out the excess aqueous solution, and blowing it dry with an air gun; S5: further allowing the oil solution to contact the membrane surface for a period of time, pouring out the excess oil solution; S6: finally allowing the short linear amine solution to contact the newly formed polyamide layer for a period of time; S7: pouring out the excess short linear amine solution, and heat curing treatment in an oven for a period of time; S8: storing the newly formed membrane in deionized water.

[0005] Preferably, the porous organic support membrane is one of polysulfone (PSf), polyacrylonitrile (PAN), poly(phenylene ether nitrile ketone) (PPENK) or polyether sulfone (PES).

[0006] Preferably, the polyamine aqueous solution is fully absorbed on the porous organic support membrane for 30s to 60s.

[0007] Preferably, the reaction time of pouring the polyacyl chloride organic solution onto the porous organic support membrane is 10s to 120s.

[0008] Preferably, the reaction time of pouring the short linear amine solution onto the porous organic support membrane is 10s to 120s.

[0009] Preferably, the oven temperature is 60 to 80°C.

[0010] Preferably, the polyamine aqueous phase reactant is one or more of m-phenylenediamine (MPD), p-phenylenediamine (PPD), and hexamethylenetetramine, and the concentration of the polyamine aqueous solution is 0.03wt% to 0.2wt%.

[0011] Preferably, the polyacyl chloride oil phase reactant is one or more of trimesoyl chloride (TMC), 2,4,6-trichloro-1,3,5-benzenetricarboxylic acid chloride, 1,3,5-triazine-2.4.6-trichloride, and the polyacyl chloride organic solution concentration is 0.005wt% to 0.02wt%, and the oil phase solvent used in the interfacial polymerization reaction is n-hexane.

[0012] Preferably, the short linear amine reactant is one or more of ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and the concentration of the short linear amine solution is 0wt% to 10.5wt%, and the solvent is anhydrous ethanol.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The present invention prepares a small-pore aminated-polyamide rolled ultrafiltration membrane. While improving the small-molecule organic matter retention rate of the rolled ultrafiltration membrane, the retention rate of inorganic salts is reduced, and the COD / inorganic salt separation effect can be improved, thereby achieving the purpose of increasing the inorganic salt reuse rate. This preparation method is simple to operate and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The SEM images of the surface of small-pore aminated-polyamide spiral ultrafiltration membrane (a), (b), (c), and (d) correspond to DETA concentrations of 0wt.%, 5wt.%, 6wt.%, and 7wt.%, respectively;

[0016] Figure 2 is the Zeta potential of small pore size aminated-polyamide spiral ultrafiltration membrane with DETA concentration of 0wt.%, 5wt.%, 6wt.%, and 7wt.%;

[0017] Figure 3 The water contact angle of small pore size aminated-polyamide spiral ultrafiltration membrane with DETA concentration of 0wt.%, 5wt.%, 6wt.%, and 7wt.%. DETAILED DESCRIPTION

[0018] Performance testing method for small pore size aminated-polyamide rolled ultrafiltration membrane prepared in the present invention

[0019] The pure water flux of the membrane was tested on a cross-flow filtration device with an operating pressure of 0.4 MPa and a test temperature of 25°C ± 1°C. The pure water flux of the membrane was calculated according to formula (1) and the calculation result was retained to two significant figures.

[0020]

[0021] Where:

[0022] F——pure water flux, m 3 / (m 2 h);

[0023] Q——pure water permeation, m 3 ;

[0024] A——membrane area, m 2 ;

[0025] t——test time, h.

[0026] The retention rate of Congo red (CR) was tested on a cross-flow filtration device. The influent CR concentration was 100 mg / L, the operating pressure was 0.4 MPa, and the test temperature was 25°C ± 1°C. The retention rate of CR by the membrane was calculated according to formula (2), and the calculation result was retained to two significant figures.

[0027]

[0028] Where:

[0029] R CR ——CR retention rate, %;

[0030] c 1 ——CR mass concentration of permeate, mg / L;

[0031] c 2 ——Mass concentration of feed liquid CR, mg / L.

[0032] Sodium sulfate (Na 2 SO 4 ) retention rate, influent Na 2 SO 4 The concentration is 2000 mg / L, the operating pressure is 0.4 MPa, and the test temperature is 25°C ± 1°C. According to formula (3), the membrane's Na 2 SO 4 The interception rate (%), the calculation result is retained to two significant figures.

[0033]

[0034] Where:

[0035] R s ——Na 2 SO 4 Retention rate, %;

[0036] c 3 ——Permeate Na 2 SO 4 Mass concentration, mg / L;

[0037] c 4 ——Feed liquid Na 2 SO 4 Mass concentration, mg / L.

[0038] According to formula (4), the membrane CR / Na 2 SO 4 The calculation result retains two significant figures.

[0039]

[0040] Where:

[0041] N——CR / Na 2 SO 4 The separation degree;

[0042] R CR ——CR retention rate, %;

[0043] R s ——Na 2 SO 4 Retention rate, %.

[0044] In order to enable those skilled in the art to clearly understand the present invention, the present invention is further described in detail below in conjunction with the examples, but it should be understood that the following examples are only preferred embodiments of the present invention, and the scope of protection claimed in the present invention is not limited thereto.

[0045] Embodiment 1:

[0046] S1: First, prepare a 0.1wt.% MPD aqueous solution; S2: Then prepare a 0.01wt.% TMC oil solution; S3: Then prepare a 3.5wt.% DETA solution; S4: Then, blow dry the PSf bottom membrane with an air gun, let the aqueous solution contact the membrane surface for 30s, then pour out the excess aqueous solution, and blow dry with an air gun; S5: Further let the oil solution contact the membrane surface for 60s, pour out the excess oil solution; S6: Finally, let the short linear amine solution contact the newly formed polyamide layer for 60s; S6: Pour out the excess DETA solution, and heat cure in an oven for 5min. The measured pure water flux of the small-pore aminated-polyamide spiral ultrafiltration membrane is 30LMH; the retention rate of CR is 94%; and the retention rate of sodium sulfate is 36%.

[0047] Embodiment 2:

[0048] S1: First, prepare a 0.1wt.% MPD aqueous solution; S2: Then prepare a 0.01wt.% TMC oil solution; S3: Then prepare a 4wt.% DETA solution; S4: Then, blow dry the PSf bottom membrane with an air gun, let the aqueous solution contact the membrane surface for 30s, then pour out the excess aqueous solution, and blow dry with an air gun; S5: Further let the oil solution contact the membrane surface for 60s, pour out the excess oil solution; S6: Finally, let the short linear amine solution contact the newly formed polyamide layer for 60s; S6: Pour out the excess DETA solution, and heat cure in an oven for 5min. The measured pure water flux of the small-pore aminated-polyamide spiral ultrafiltration membrane is 35LMH; the retention rate of CR is 94%; the retention rate of sodium sulfate is 24%.

[0049] Embodiment 3:

[0050] S1: First, prepare a 0.1wt.% MPD aqueous solution; S2: Then prepare a 0.01wt.% TMC oil solution; S3: Then prepare a 5wt.% DETA solution; S4: Then, use an air gun to blow dry the PSf bottom membrane, let the aqueous solution contact the membrane surface for 30s, then pour out the excess aqueous solution and blow dry with an air gun; S5: Further let the oil solution contact the membrane surface for 60s, pour out the excess oil solution; S6: Finally, let the short linear amine solution contact the newly formed polyamide layer for 60s; S6: Pour out the excess DETA solution and heat cure in an oven for 5min. The measured pure water flux of the small-pore aminated-polyamide spiral ultrafiltration membrane is 55LMH; the retention rate of CR is 94%; the retention rate of sodium sulfate is 15%.

[0051] Embodiment 4:

[0052] S1: First, prepare a 0.1wt.% MPD aqueous solution; S2: Then prepare a 0.01wt.% TMC oil solution; S3: Then prepare a 6wt.% DETA solution; S4: Then, blow dry the PSf bottom membrane with an air gun, let the aqueous solution contact the membrane surface for 30s, then pour out the excess aqueous solution, and blow dry with an air gun; S5: Further let the oil solution contact the membrane surface for 60s, pour out the excess oil solution; S6: Finally, let the short linear amine solution contact the newly formed polyamide layer for 60s; S6: Pour out the excess DETA solution, and heat cure it in an oven for 5min. The measured pure water flux of the small-pore aminated-polyamide spiral ultrafiltration membrane is 50LMH; the retention rate of CR is 94%; the retention rate of sodium sulfate is 3%.

[0053] Embodiment 5:

[0054] S1: First, prepare a 0.1wt.% MPD aqueous solution; S2: Then prepare a 0.01wt.% TMC oil solution; S3: Then prepare a 7wt.% DETA solution; S4: Then, blow dry the PSf bottom membrane with an air gun, let the aqueous solution contact the membrane surface for 30s, then pour out the excess aqueous solution, and blow dry with an air gun; S5: Further let the oil solution contact the membrane surface for 60s, pour out the excess oil solution; S6: Finally, let the short linear amine solution contact the newly formed polyamide layer for 60s; S6: Pour out the excess DETA solution, and heat cure in an oven for 5min. The measured pure water flux of the small-pore aminated-polyamide spiral ultrafiltration membrane is 45LMH; the retention rate of CR is 94%; the retention rate of sodium sulfate is 15%.

[0055] Embodiment 6:

[0056] S1: First, prepare a 0.1wt.% MPD aqueous solution; S2: Then prepare a 0.01wt.% TMC oil solution; S3: Then prepare a 8wt.% DETA solution; S4: Then, blow dry the PSf bottom membrane with an air gun, let the aqueous solution contact the membrane surface for 30s, then pour out the excess aqueous solution, and blow dry with an air gun; S5: Further let the oil solution contact the membrane surface for 60s, pour out the excess oil solution; S6: Finally, let the short linear amine solution contact the newly formed polyamide layer for 60s; S6: Pour out the excess DETA solution, and heat cure in an oven for 5min. The measured pure water flux of the small-pore aminated-polyamide spiral ultrafiltration membrane is 35LMH; the retention rate of CR is 94%; and the retention rate of sodium sulfate is 20%.

[0057] Embodiment 7:

[0058] S1: First, prepare an MPD aqueous solution with a mass concentration of 0.1wt.%; S2: Then prepare a TMC oil solution with a mass concentration of 0.01wt.%; S3: Then prepare a DETA solution with a mass concentration of 10.5wt.%; S4: Then, use an air gun to blow dry the PSf base membrane, allow the aqueous solution to contact the membrane surface for 30s, then pour out the excess aqueous solution and blow dry with an air gun; S5: Further allow the oil solution to contact the membrane surface for 60s, pour out the excess oil solution; S6: Finally, allow the short linear amine solution to contact the newly formed polyamide layer for 60s; S6: Pour out the excess DETA solution and heat cure it in an oven for 5min. The measured pure water flux of the small-pore aminated-polyamide rolled ultrafiltration membrane is 28LMH; the retention rate of CR is 94%; and the retention rate of sodium sulfate is 40%.

Claims

1. A method for preparing a small-pore aminated polyamide spiral ultrafiltration membrane, the preparation scheme The following steps are involved: S1: First, prepare MPD aqueous solutions with different mass concentrations; S2: Then prepare TMC oil phase solutions of different mass concentrations; S3: Then prepare short linear amine solutions of different mass concentrations; S4: Then blow dry the PSf bottom membrane with an air gun, let the water phase solution contact with the membrane surface for a period of time, then pour out the excess water phase solution, and blow dry with an air gun; S5: Further let the oil phase solution contact with the membrane surface for a period of time, pour out the excess oil phase solution; S6: Finally, let the short linear amine solution contact with the newly formed polyamide layer for a period of time; S6: pour out the excess short linear amine solution and heat cure it in an oven for a period of time; S7: Store the newly formed membrane in deionized water.

2. The method for preparing a small-pore-size aminated-polyamide spiral ultrafiltration membrane according to claim 1, characterized in that: The porous organic support membrane is one of polysulfone (PSf), polyacrylonitrile (PAN), poly(phthalazine biphenyl ether nitrile ketone) (PPENK) or polyethersulfone (PES).

3. The method for preparing a small-pore aminated-polyamide spiral ultrafiltration membrane according to claim 1, characterized in that: The time for the polyamine aqueous solution to be fully absorbed on the porous organic support membrane is 30s to 60s.

4. The method for preparing a small-pore aminated-polyamide spiral ultrafiltration membrane according to claim 1, characterized in that: The reaction time of pouring the polyacyl chloride organic solution onto the porous organic support membrane is 10s to 120s.

5. The method for preparing a small-pore aminated-polyamide spiral ultrafiltration membrane according to claim 1, characterized in that: The reaction time of pouring the short linear amine solution onto the porous organic support membrane is 10s to 120s.

6. The method for preparing a small-pore aminated-polyamide spiral ultrafiltration membrane according to claim 1, characterized in that: The oven temperature is 60-80°C.

7. The method for preparing a small-pore aminated-polyamide spiral ultrafiltration membrane according to claim 3, characterized in that: The polyamine aqueous phase reactant is one or more of metaphenylenediamine (MPD), paraphenylenediamine (PPD), and hexamethylenetetramine, and the concentration of the polyamine aqueous solution is 0.03wt% to 0.2wt%.

8. The method for preparing a small-pore aminated-polyamide spiral ultrafiltration membrane according to claim 4, characterized in that: The polyacyl chloride oil phase reactant is one or more of trimesoyl chloride (TMC), 2,4,6-trichloro-1,3,5-benzenetricarboxylic acid chloride, 1,3,5-triazine-2.4.6-trichloride, and the concentration of the polyacyl chloride organic solution is 0.005wt% to 0.02wt%, and the oil phase solvent used in the interfacial polymerization reaction is n-hexane.

9. The method for preparing a small-pore aminated-polyamide spiral ultrafiltration membrane according to claim 1, characterized in that: The short linear amine reactant is one or more of ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), and pentaethylenehexamine (PEHA), and the concentration of the short linear amine solution is 0wt% to 10.5wt%, and the solvent is anhydrous ethanol.

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