CN114733370A - Layer-by-layer self-assembly preparation method of sulfonated graphene nanofiltration membrane - Google Patents

Layer-by-layer self-assembly preparation method of sulfonated graphene nanofiltration membrane Download PDF

Info

Publication number
CN114733370A
CN114733370A CN202210564505.5A CN202210564505A CN114733370A CN 114733370 A CN114733370 A CN 114733370A CN 202210564505 A CN202210564505 A CN 202210564505A CN 114733370 A CN114733370 A CN 114733370A
Authority
CN
China
Prior art keywords
membrane
pei
layer
solution
nanofiltration membrane
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202210564505.5A
Other languages
Chinese (zh)
Other versions
CN114733370B (en
Inventor
邵文尧
王蕊
陈玉清
彭雅娟
罗世翊
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xiamen University
Original Assignee
Xiamen University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xiamen University filed Critical Xiamen University
Priority to CN202210564505.5A priority Critical patent/CN114733370B/en
Publication of CN114733370A publication Critical patent/CN114733370A/en
Application granted granted Critical
Publication of CN114733370B publication Critical patent/CN114733370B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/027—Nanofiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0086—Mechanical after-treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0095—Drying
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B01D69/125—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02—Inorganic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/44—Polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds, not provided for in a single one of groups B01D71/26-B01D71/42
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/66—Polymers having sulfur in the main chain, with or without nitrogen, oxygen or carbon only
    • B01D71/68—Polysulfones; Polyethersulfones
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/12—Specific ratios of components used
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/50—Control of the membrane preparation process
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/26—Electrical properties
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis

Abstract

A layer-by-layer self-assembly preparation method of a sulfonated graphene nanofiltration membrane belongs to the field of nanofiltration membrane preparation. The method comprises the following steps: fully mixing SG solution and PEI solution and performing ultrasonic treatment to obtain mixed solution; a PES membrane in an ultrafiltration cup is pre-pressed stably; and pouring the mixed solution after ultrasonic treatment into an ultrafiltration cup containing a PES (polyether sulfone) membrane for pressure filtration, and drying the membrane to obtain the sulfonated graphene nanofiltration membrane. SG and PEI are used as a common stacking material to prepare the self-assembled nanofiltration membrane, the SG has better dispersibility than common graphene, PEI can provide amino, the combination of the SG and the PEI is favorable for stacking and forming a membrane, and the positive electrical property of the surface of the membrane can be enhanced, the PES membrane is well combined with SG/PEI, the concentration of SG is 0.2mg/mL, the performance of the membrane is optimal when the concentration of PEI is 0.05%, and the water flux is 8.5LMH at the moment. Evans blue retention was 99.15%. Compared with a self-assembled membrane which is formed by simply stacking PEI, the membrane shows a certain water flux improvement.

Description

Layer-by-layer self-assembly preparation method of sulfonated graphene nanofiltration membrane
Technical Field
The invention belongs to the field of nanofiltration membrane preparation, and particularly relates to a layer-by-layer self-assembly preparation method of a sulfonated graphene nanofiltration membrane, which utilizes a polyether sulfone (PES) ultrafiltration membrane as a base membrane and Polyethyleneimine (PEI) as a cationic additive, and mixes and stacks Sulfonated Graphene (SG).
Background
The nanofiltration membrane has high removal rate to specific particles due to the unique surface charge characteristic and smaller aperture, and belongs to a pressure driving membrane, so that the nanofiltration technology has the advantages of low operation pressure, low energy consumption, high operation cost-effectiveness ratio, high automation, high flux and the like in the membrane separation process, and has wide application prospect in the aspect of water purification treatment. Although the nanofiltration membrane has high rejection rate of organic matters with high-valence salts and low relative molecular mass, the rejection rate of the nanofiltration membrane to monovalent inorganic salts is rapidly reduced along with the increase of the concentration of the solution.
In the preparation method of the nanofiltration membrane, an interfacial polymerization method, an L-S phase conversion method, a chemical modification method, a Layer-by-Layer self-assembly method, and the like are included at present, wherein a Layer-by-Layer self-assembly (LBL) technology is used as a new technology which is rapidly developing, and the stacking of assembly materials can be easily realized. The layer-by-layer self-assembly plays an increasingly important role in the fields of chemistry, physics, biology, materials, nano science, medicine and the like, and the progress of science and technology and the development of economy are continuously promoted.
The high-performance membrane material can better realize the nano-grade (0.5-2 nm) aperture of the nanofiltration membrane. The graphene composite material has a plurality of excellent performances, and the unique structure of the graphene composite material is beneficial to surface functionalization to obtain modified graphene with more excellent performances, for example, oxidized graphene obtained through oxidation improves the hydrophilicity of graphene due to introduced hydroxyl and carboxyl, sulfonated graphene obtained through sulfonation also has good dispersibility, and the graphene composite material is a promising membrane preparation material.
Disclosure of Invention
The invention aims to provide a layer-by-layer self-assembly preparation method of a sulfonated graphene nanofiltration membrane. The PES ultrafiltration membrane is used as a bottom membrane, Polyethyleneimine (PEI) and Sulfonated Graphene (SG) are used as stacking materials, and a layer-by-layer self-assembly technology is utilized, so that the nanofiltration membrane which is high in monovalent inorganic salt rejection rate, wide in application range and better in membrane performance is prepared.
The invention comprises the following steps:
1) preparing 80mL of SG solution, and carrying out ultrasonic treatment;
2) preparing 80mL of PEI aqueous solution, and magnetically stirring for 1 h;
3) fully mixing 80mL of SG solution and 80mL of PEI aqueous solution, and carrying out ultrasonic treatment;
4) fixing a bottom membrane in an ultrafiltration cup, and performing pressure filtration on 100mL of ultrapure water at 1bar for prepressing stabilization;
5) pouring mixed liquid obtained by fully mixing SG and PEI after ultrasonic treatment into an ultrafiltration cup containing a base membrane for pressure filtration, transferring PEI and SG to a membrane with a PES ultrafiltration base membrane, and placing the membrane into a 60 ℃ oven for forced air drying for 1h to obtain the sulfonated graphene nanofiltration membrane.
In the step 1), the concentration of the SG solution can be 0.01-0.4 mg/mL, preferably 0.2 mg/mL; the ultrasonic time can be 1h, and the ultrasonic frequency is 60 Hz;
in the step 2), the mass percentage concentration of the PEI aqueous solution can be 0.01-0.4 wt%, preferably 0.05 wt%; the magnetic stirring time can be more than 1 h.
In the step 3), the volume of the SG solution and the polyethyleneimine aqueous solution is 1: 1; the ultrasonic time can be 20min, and the SG solution and the PEI solution are fully mixed and then subjected to ultrasonic treatment to further enhance the dispersibility of SG in the solution.
In the step 4), the PES ultrafiltration bottom membrane is adopted, and before use, the PES ultrafiltration bottom membrane can be soaked in ultrapure water for more than 1h and pre-pressed with 100mL of ultrapure water at 1 bar.
In the step 5), the pressure filtration is stopped when the volume of the permeate is 125mL, and the pressure does not exceed 1.6 bar. The water flux of the prepared sulfonated graphene nanofiltration membrane is 8.5LMH, and the Evans blue retention rate is 99.15%.
The volume of the filtering solution is determined to design the loading capacity of the accumulated material on the surface of the membrane; the uniform dispersion of SG in water is realized, PEI is used as an additive to stack together in the process of pressure filtration to avoid the agglomeration of SG, and the surface integrity of the prepared self-assembled membrane is ensured.
Compared with the prior art, the invention has the outstanding advantages that: according to the invention, SG and PEI are used as a common stacking material to prepare the self-assembled nanofiltration membrane, SG has better dispersibility than common graphene, PEI can provide amino, and the combination of the SG and the PEI is favorable for stacking to form a membrane and can strengthen the positive electric property of the surface of the membrane, which cannot be achieved by common graphene oxide. The optimal membrane preparation conditions for screening in the invention are that the concentration of SG is 0.2mg/mL and the concentration of PEI is 0.05 wt%, the water flux of the prepared sulfonated graphene nanofiltration membrane is 8.5LMH, the retention rate of Evans blue is 99.15%, and the sulfonated graphene nanofiltration membrane shows excellent dye retention performance compared with the retention rate of 68.41% of basement membrane. Compared with a self-assembled membrane which is formed by simply stacking PEI, the membrane shows a certain water flux improvement.
Drawings
FIG. 1 is a schematic view of an apparatus for preparing self-assembled films and testing the performance of the films.
FIG. 2 is a standard curve of Evans blue concentration. The standard curve is plotted by absorbance measured by an ultraviolet spectrophotometer.
Figure 3 is a graph of the effect of stacking PEI concentration alone (in wt%) on self-assembled nanofiltration membrane performance.
Figure 4 is a graph of the effect of SG concentration (expressed in mg/mL) on the performance of self-assembled nanofiltration membranes at a fixed PEI concentration of 0.05 wt%.
FIG. 5 is an SEM image of the surface of a self-assembled nanofiltration membrane at different SG concentrations at a fixed PEI concentration of 0.05 wt%. Wherein, a: c. C(SG)＝0.1mg/mL，b：c(SG)＝0.2mg/mL，c：c(SG)＝0.3mg/mL，d：c(SG)＝0.4mg/mL。
FIG. 6 shows the cross-section of the self-assembled nanofiltration membrane at different SG concentrations when the fixed PEI concentration is 0.05 wt%SEM image. Wherein, a1：c(SG)＝0.1mg/mL，b1：c(SG)＝0.2mg/mL，c1：c(SG)＝0.3mg/mL，d1：c(SG)＝0.4mg/mL。
Fig. 7 is an infrared spectrum of a PES base film, a self-assembled film stacked with PEI material only, and SG/PEI composite.
FIG. 8 is a schematic diagram showing the influence of water contact angle on the surface of SG/PEI self-assembled nanofiltration membrane under different SG concentrations.
FIG. 9 shows the surface morphology of SG/PEI self-assembled nanofiltration membranes at different SG concentrations at a fixed PEI concentration of 0.05 wt%. Wherein (I) c(SG)＝0.1mg/mL，(II)c(SG)＝0.2mg/mL，(III)c(SG)＝0.3mg/mL，(IV)c(SG)＝0.4mg/mL。
Detailed Description
In order to facilitate a better understanding of the technology of the present invention for those skilled in the art, some non-limiting examples will now be further disclosed to further illustrate the invention. The reagents used in the present invention are either commercially available directly or can be prepared by the methods described in the present invention.
According to the invention, Polyethyleneimine (PEI) and Sulfonated Graphene (SG) are used as self-assembly stacking materials, a PES ultrafiltration membrane is used as a bottom membrane, a new nanofiltration membrane with better membrane performance is prepared by a layer-by-layer self-assembly technology, and the new nanofiltration membrane is characterized and analyzed. The following are specific implementation steps in the membrane preparation process.
1. Preparing a layer-by-layer self-assembled film:
example 1:
80mL of a 0.05 wt% aqueous polyethyleneimine solution was prepared, and the solution was magnetically stirred for 1 hour to measure the pH. The mixture was thoroughly mixed with 80mL of ultrapure water, and the pH was measured after 20min of sonication. A PES ultrafiltration base membrane is arranged in an ultrafiltration cup (shown in figure 1) (the PES ultrafiltration base membrane is soaked in ultrapure water for more than 1h before use), and 100mL of ultrapure water is subjected to pressure filtration at 1bar for prepressing; pouring the polyethyleneimine aqueous solution into an ultrafiltration cup, filtering 125mL of filtrate under the pressure of 1.6bar, pouring out the residual mixed solution, and taking out a membrane; and (3) placing the membrane in an oven at 60 ℃ for forced air drying for 1h for standby.
Example 2:
80mL of the polyethyleneimine aqueous solution prepared in the first step of example 1 was treated in the same manner as in example 1, except that the concentration was 0.1 wt%.
Example 3:
80mL of the polyethyleneimine aqueous solution prepared in the first step in example 1 was treated in the same manner as in example 1, except that the concentration was 0.2 wt%.
Example 4:
80mL of the polyethyleneimine aqueous solution prepared in the first step of example 1 was treated in the same manner as in example 1, except that the concentration was 0.3 wt%.
Example 5:
80mL of the polyethyleneimine aqueous solution prepared in the first step in example 1 was treated in the same manner as in example 1, except that the concentration was 0.4 wt%.
Example 6:
preparing 80mL of 0.1mg/mL sulfonated graphene aqueous solution, performing ultrasonic treatment for 1h at 60Hz, and measuring the pH value of the sulfonated graphene aqueous solution; 80mL of a 0.05 wt% aqueous polyethyleneimine solution was prepared, and the solution was magnetically stirred for 1 hour to measure the pH. And fully mixing 80mL of sulfonated graphene solution and 80mL of polyethyleneimine water solution, and carrying out ultrasonic treatment for 20min to determine the pH value of the mixed solution. A PES ultrafiltration basement membrane is arranged in an ultrafiltration cup (shown in figure 1) (the PES ultrafiltration basement membrane is soaked in ultrapure water for more than 1h before use), and 100mL of ultrapure water is pre-pressed under 1bar for pre-pressing; pouring the mixed solution into an ultrafiltration cup, filtering 125mL of filtrate under the pressure of 1.6bar, pouring out the residual mixed solution and taking out a membrane; the membrane was placed in an oven at 60 ℃ and dried by air blow for 1h until ready for use (see FIG. 9 (I)).
Example 7:
the membrane surface morphology was as shown in FIG. 9(II) by changing the concentration of the 80mL polyethyleneimine aqueous solution prepared in the first step in example 6 to 0.2mg/mL and performing the same treatment as in example 1.
Example 8:
the membrane surface morphology was as shown in FIG. 9(III) by changing the concentration of the 80mL polyethyleneimine aqueous solution prepared in the first step in example 6 to 0.3mg/mL and performing the same treatment as in example 1.
Example 9:
the membrane surface morphology was as shown in FIG. 9(IV) by changing the concentration of the 80mL polyethyleneimine aqueous solution prepared in the first step in example 6 to 0.4mg/mL and performing the same treatment as in example 1.
2. And (3) film appearance characterization:
the surface morphology and the section structure of the film are observed and characterized by a SIGMA type scanning electron microscope of ZEISS company in Germany: the main steps of surface morphology observation are that the dried sample film is cut and sprayed with gold to improve the conductivity of the sample, then the scanning electron microscope sample is stuck on the sample seat conductive adhesive tape, the sample seat is placed in a sample chamber, and the sample chamber is vacuumized and pressurized to observe the sample. The surface morphology of the sample of the embodiment is characterized under the acceleration voltage of 20KV and the magnification of 20000 times (the results of the embodiments 6-9 are shown in the graphs a-d in FIG. 5); the section structure observation comprises the steps of firstly putting a dried sample in liquid nitrogen for brittle processing, then taking out the sample for instantaneous fracture, vertically adhering the section to a sample seat conductive adhesive tape with the section facing upwards, and performing section structure characterization on the sample in the embodiment under the conditions of the accelerating voltage of 20KV and the magnification of 10000 times (the results of the embodiments 6-9 are shown as a graph a in figure 6)1～d1Shown), the film thickness of each film is marked on the figure.
3. Analysis of membrane surface groups:
the membrane surface chemistry was analyzed using a VERTXE 70 Fourier transform infrared spectrometer from Bruker spectroscopic instruments, Germany. The main principle is that a Michelson interferometer is used to make two beams of infrared light with optical path difference changing according to a certain speed form interference light, then the interference light and a sample are acted, and a computer is used to perform Fourier transform on an interference signal detected by a detector to obtain a spectrogram. The results of IR spectroscopy for examples 6 to 9 are shown in FIG. 7, 3307cm-1The characteristic peak may be-OH brought by dehydrating agent added in the commodity membrane, etc., because compared with standard infrared spectrum of PES basement membrane, 3307cm-1The treatment should be smoother; 1680cm-1The characteristic peak is the stretching vibration of-C ═ C-; 648cm-1The characteristic peak is the characteristic peak of sulfonic acid group; PES basement membrane + PEI membrane with-C-at 1680cm-1Band shifts occur, which indicates that an interaction occurs between the vinyl group and the polyethersulfone; 648cm in PES bottom membrane + PEI + SG membrane-1The characteristic peak indicates that sulfonic acid groups are successfully introduced into the membrane surface; as SG and PEI are added simultaneously, the film layer is too thick, so that the intensity of each peak in the PES basement film + PEI + SG film is not enough.
4. And (3) determining the hydrophilic and hydrophobic performances of the membrane:
the contact angle of the film surface is measured by an SPCAX3 contact angle measuring instrument produced by Beijing Hake test instrument factory: the sample was cut into 1X 1cm2Size, test on a glass slide with double-sided tape, and average value was taken after 5 measurements of each sample. The water contact angle results for each example are shown in fig. 8. When the SG concentration is 0.2mg/mL, the contact angle is the smallest, the membrane has the best hydrophilicity, and probably because the hydrophilic group content on the membrane surface is higher, water molecules are promoted to move to the membrane surface, and the water flux is increased. While as the concentration of SG increases, the degree of film surface stacking increases resulting in an increase in film surface roughness, such that the contact angle increases.
5. Testing the membrane separation performance:
the evaluation parameters of the separation performance of the nanofiltration membrane mainly comprise two aspects of water flux and rejection rate, and the membrane separation performance test is carried out by adopting a Stired Cell 400mL type ultrafiltration cup produced by Amicon company in Germany. The testing device mainly comprises a nitrogen steel cylinder connected with an ultrafiltration cup capable of high-pressure operation, and the tail end of the testing device is connected with a measuring cylinder for measuring the volume of the permeation liquid and calculating the water flux. The effective test area of the membrane in the ultrafiltration cup is about 40cm2。
5.1 Water flux test:
the flux of the membrane, also called the permeation rate, refers to the volume of liquid passing through the membrane per unit area under a certain pressure in a unit time, and the calculation formula is as follows:
Figure BDA0003657326880000051
j-flux of membrane, LMH; q-permeate volume in a certain time, unit: l; s-effective area of the film, m2(ii) a t-test time, unit: h.
pouring 300mL of ultrapure water into a device, and pre-pressing 50mL under the condition of 4 bar; after the pre-pressing is finished, keeping the condition unchanged, and measuring the volume Q of the permeation liquid within t time; finally, the water flux is calculated by formula 1.
5.2 rejection test:
the rejection rate of the membrane represents the rejection capacity of the membrane for a certain solute, and is another important index of the membrane separation process, and the calculation formula is as follows:
Figure BDA0003657326880000061
in the formula, the retention rate of the R-membrane is percent; c1Permeate concentration, unit: g/L; c2Initial concentration of feed liquid, unit: g/L.
Evans blue retention test:
300mL of evans blue aqueous solution with the concentration of 50mg/L is prepared, and 10mL of evans blue aqueous solution is pre-pressed under the condition of 4bar after the evans blue aqueous solution is poured into the device; after the pre-pressing is finished, the condition is kept unchanged, the volume Q of the permeation liquid in the time t is measured, and the water flux is calculated according to the formula 1. Measuring the absorbance of the concentrated solution and the permeation solution by using an ultraviolet spectrophotometer; evans blue ABS-concentration standard curve plotted (see fig. 2): ABS 0.07613c +0.00633 (r)20.99975) the corresponding evans blue concentration was calculated and the membrane rejection for evans blue was calculated from equation 2.
FIG. 1 is a schematic view of an apparatus for preparing self-assembled films and testing the performance of the films. Mainly comprises a nitrogen steel cylinder connected with an ultrafiltration cup capable of operating under high pressure, and a lifting platform for adjusting the height.
FIG. 3 shows the flux and rejection of the membranes of examples 1 to 5, with a preferred PEI concentration of 0.05 wt%.
FIG. 4 shows the membrane flux and rejection of examples 6 to 9, with a preferred SG concentration of 0.2 mg/mL.
Analysis of the above characterization and film performance results led to the following conclusions:
when the concentration of PEI is 0.05 wt%, the flux of the nanofiltration membrane is increased and then reduced, the rejection rate is reduced and then increased along with the increase of SG concentration, but the total content is maintained to be more than 99%. The entrapment rate of the membrane without adding SG to Ewensky blue is 68.41%, compared with that after adding SG, the entrapment rate is greatly improved, probably because sulfonic acid groups on SG are combined with amino groups on PEI, and the membrane is more compact due to layer-by-layer assembly and deposition on the surface of the membrane. And when the concentration of SG is 0.2mg/mL, the flux of the membrane is highest, the retention rate is relatively low, but the retention rate is still kept above 99%, probably because the membrane surface contains abundant hydrophilic groups, and the resistance of the mass transfer process of water is reduced. From the results of SEM, it was also confirmed that as the SG concentration was further increased, the thickness of the dense layer on the membrane surface was further increased, and the fluid resistance continued to increase, resulting in the start of a decrease in water flux.
Experiments prove that: compared with the common graphene, the SG has better dispersibility, PEI can provide amino, the combination of the amino and the PEI is favorable for stacking and forming a film, and the positive electric property of the surface of the film can be enhanced, which cannot be achieved by the common graphene oxide. The PEI ensures the stability and the integrity of the membrane structure, prevents SG from agglomerating, and enables the concentration of SG to be in the range of 0-0.4 mg/mL to form a membrane. The optimal membrane preparation conditions for screening in the invention are that the concentration of SG is 0.2mg/mL and the concentration of PEI is 0.05 wt%, the water flux of the prepared sulfonated graphene nanofiltration membrane is 8.5LMH, the retention rate of Evans blue is 99.15%, and the sulfonated graphene nanofiltration membrane shows excellent dye retention performance compared with the retention rate of 68.41% of basement membrane. Compared with a self-assembled membrane which is formed by simply stacking PEI, the membrane shows a certain water flux improvement.
The invention discloses a method for preparing a sulfonated graphene nanofiltration membrane by a layer-by-layer self-assembly technology. Sulfonated Graphene (SG) and Polyethyleneimine (PEI) are selected as self-assembly stacking materials, and the influence of the assembly concentration and the loading capacity of the sulfonated graphene and the polyethyleneimine on the separation performance of the nanofiltration membrane is inspected. By performing characterization such as scanning electron microscope, infrared spectrum, contact angle and the like on the film, the following results are obtained: the polyether sulfone (PES) ultrafiltration membrane is well combined with SG/PEI, the concentration of SG is 0.2mg/mL, and the membrane performance is best when the concentration of PEI is 0.05%. The water flux at this point was 8.5 LMH. Evans blue retention was 99.15%. This is due to the large number of hydrophilic groups brought by the addition of SG and PEI together with the dense membrane layer formed by their addition, which affects the membrane performance.
The above is only a preferred embodiment of the present invention, and it will be apparent to those skilled in the art that several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be considered as the protection scope of the present invention.

Claims (10)

1. A layer-by-layer self-assembly preparation method of a sulfonated graphene nanofiltration membrane is characterized by comprising the following steps:
1) preparing 80mL of SG solution, and carrying out ultrasonic treatment;
2) preparing 80mL of PEI aqueous solution, and magnetically stirring for 1 h;
3) fully mixing 80mL of SG solution with 80mL of PEI aqueous solution, and carrying out ultrasonic treatment to obtain a mixed solution;
4) fixing a bottom membrane in an ultrafiltration cup, and performing pressure filtration on 100mL of ultrapure water at 1bar for prepressing stabilization;
5) pouring the mixed solution obtained in the step 3) into an ultrafiltration cup containing a base membrane for pressure filtration, transferring PEI and SG to a membrane with a PES ultrafiltration base membrane, and placing the membrane in an oven for forced air drying to obtain the sulfonated graphene nanofiltration membrane.
2. The layer-by-layer self-assembly preparation method of the sulfonated graphene nanofiltration membrane according to claim 1, wherein in the step 1), the concentration of the SG solution is 0.01-0.4 mg/mL; the ultrasonic time is 1h, and the ultrasonic frequency is 60 Hz.
3. The method of claim 2, wherein the concentration of the SG solution is 0.2 mg/mL.
4. The layer-by-layer self-assembly preparation method of the sulfonated graphene nanofiltration membrane according to claim 1, wherein in the step 2), the mass percentage concentration of the PEI aqueous solution is 0.01-0.4 wt%; the magnetic stirring time is more than 1 h.
5. The method of claim 4, wherein the mass percentage concentration of the PEI aqueous solution is 0.05 wt%.
6. The layer-by-layer self-assembly preparation method of a sulfonated graphene nanofiltration membrane according to claim 1, wherein in the step 3), the volume of the SG solution and the polyethyleneimine aqueous solution is 1: 1.
7. The layer-by-layer self-assembly preparation method of the sulfonated graphene nanofiltration membrane according to claim 1, wherein in the step 3), the ultrasonic treatment is performed for 20min, and after the SG solution and the PEI solution are fully mixed, the SG solution is subjected to ultrasonic treatment to further enhance the dispersibility of SG in the solution.
8. The layer-by-layer self-assembly preparation method of the sulfonated graphene nanofiltration membrane according to claim 1, wherein in the step 4), the PES ultrafiltration bottom membrane is adopted, and before use, the PES ultrafiltration bottom membrane is soaked in ultrapure water for more than 1h, and 100mL of ultrapure water is pre-pressed at 1 bar.
9. The method for preparing a sulfonated graphene nanofiltration membrane by layer-by-layer self-assembly according to claim 1, wherein in the step 5), the pressure filtration is stopped when the volume of the permeate is 125mL, and the pressure is not more than 1.6 bar.
10. The sulfonated graphene nanofiltration membrane prepared by the preparation method of any one of claims 1 to 9.
CN202210564505.5A 2022-05-23 2022-05-23 Layer-by-layer self-assembly preparation method of sulfonated graphene nanofiltration membrane Active CN114733370B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210564505.5A CN114733370B (en) 2022-05-23 2022-05-23 Layer-by-layer self-assembly preparation method of sulfonated graphene nanofiltration membrane

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210564505.5A CN114733370B (en) 2022-05-23 2022-05-23 Layer-by-layer self-assembly preparation method of sulfonated graphene nanofiltration membrane

Publications (2)

Publication Number Publication Date
CN114733370A true CN114733370A (en) 2022-07-12
CN114733370B CN114733370B (en) 2023-11-24

Family

ID=82286772

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210564505.5A Active CN114733370B (en) 2022-05-23 2022-05-23 Layer-by-layer self-assembly preparation method of sulfonated graphene nanofiltration membrane

Country Status (1)

Country Link
CN (1) CN114733370B (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105038222A (en) * 2015-08-11 2015-11-11 河南科技大学 Graphene/PEI (polyethyleneimine) gas barrier composite membrane and preparing method of graphene/PEI gas barrier composite membrane
WO2021194418A1 (en) * 2020-03-24 2021-09-30 National University Of Singapore A semi-permeable membrane
CN114130197A (en) * 2020-09-04 2022-03-04 三达膜科技（厦门）有限公司 Graphene oxide titanium dioxide-dopamine PEI nanofiltration membrane and preparation method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105038222A (en) * 2015-08-11 2015-11-11 河南科技大学 Graphene/PEI (polyethyleneimine) gas barrier composite membrane and preparing method of graphene/PEI gas barrier composite membrane
WO2021194418A1 (en) * 2020-03-24 2021-09-30 National University Of Singapore A semi-permeable membrane
CN114130197A (en) * 2020-09-04 2022-03-04 三达膜科技（厦门）有限公司 Graphene oxide titanium dioxide-dopamine PEI nanofiltration membrane and preparation method thereof

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
NATÁLIA CÂNDIDO HOMEMA: "Surface modification of a polyethersulfone microfiltration membrane with graphene oxide for reactive dyes removal", 《APPLIED SURFACE SCIENCE》, vol. 486, 1 May 2019 (2019-05-01), pages 500 *
QUANLING XIE: "Preparation and characterization of novel alkaliresistant nanofiltration membranes with enhanced permeation and antifouling properties: the effects of functionalized graphene nanosheets", 《RSC ADVANCES》 *
QUANLING XIE: "Preparation and characterization of novel alkaliresistant nanofiltration membranes with enhanced permeation and antifouling properties: the effects of functionalized graphene nanosheets", 《RSC ADVANCES》, vol. 7, 29 March 2017 (2017-03-29), pages 18758 *
贾瑛等: "《轻质碳材料的应用》", 北京国防工业出版社, pages: 27 *

Also Published As

Publication number Publication date
CN114733370B (en) 2023-11-24

Similar Documents

Publication Publication Date Title
Ding et al. Graphene oxide-embedded nanocomposite membrane for solvent resistant nanofiltration with enhanced rejection ability
Rahimpour et al. Novel functionalized carbon nanotubes for improving the surface properties and performance of polyethersulfone (PES) membrane
Wang et al. Novel GO-blended PVDF ultrafiltration membranes
Guillen et al. Pore-structure, hydrophilicity, and particle filtration characteristics of polyaniline–polysulfone ultrafiltration membranes
Arthanareeswaran et al. Effect of silica particles on cellulose acetate blend ultrafiltration membranes: Part I
Chen et al. Synthesis and characterization of gC 3 N 4 nanosheet modified polyamide nanofiltration membranes with good permeation and antifouling properties
Amiri et al. Fabrication of chitosan-aminopropylsilane graphene oxide nanocomposite hydrogel embedded PES membrane for improved filtration performance and lead separation
Wang et al. Preparation and antifouling property of polyethersulfone ultrafiltration hybrid membrane containing halloysite nanotubes grafted with MPC via RATRP method
Alam et al. Development of polyaniline-modified polysulfone nanocomposite membrane
Liu et al. Modification of polyamide TFC nanofiltration membrane for improving separation and antifouling properties
Zhang et al. Development of phosphorylated silica nanotubes (PSNTs)/polyvinylidene fluoride (PVDF) composite membranes for wastewater treatment
Vatanpour et al. Anti-fouling polyethersulfone nanofiltration membranes aided by amine-functionalized boron nitride nanosheets with improved separation performance
Zaman et al. Polyimide-graphene oxide nanofiltration membrane: Characterizations and application in enhanced high concentration salt removal
CN112742223B (en) Modified polyamide membrane, composite membrane containing modified polyamide membrane and preparation method of composite membrane
CN113019151B (en) Graphene oxide-polyvinylidene fluoride composite hollow fiber membrane for water treatment, and preparation method and application thereof
CN102258950A (en) Polysulfone-polypyrrole nanoparticle asymmetric composite ultrafiltration film and preparation method thereof
Zhu et al. Zwitterionic SiO 2 nanoparticles as novel additives to improve the antifouling properties of PVDF membranes
Fan et al. Preparation and anti-protein fouling property of δ-gluconolactone-modified hydrophilic polysulfone membranes
Mehrparvar et al. Surface modification of novel polyether sulfone amide (PESA) ultrafiltration membranes by grafting hydrophilic monomers
Cui et al. Interfacial polymerization of MOF “monomers” to fabricate flexible and thin membranes for molecular separation with ultrafast water transport
CN112316755A (en) Composite nanofiltration membrane and preparation method thereof
Borah et al. Cyclodextrine-glutaraldehyde cross-linked nanofiltration membrane for recovery of resveratrol from plant extract
Wang et al. Porous nano-hydroxyapatites doped into substrate for thin film composite forward osmosis membrane to show high performance
Liu et al. Constructing high-performance GO membrane with pore-adjustable polymer nanoparticles
Mahmoudian et al. Utilization of a mixed matrix membrane modified by novel dendritic fibrous nanosilica (KCC-1-NH-CS 2) toward water purification

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant