CN118022561A - Reusable graphene-based ion selective membrane and application thereof - Google Patents
Reusable graphene-based ion selective membrane and application thereof Download PDFInfo
- Publication number
- CN118022561A CN118022561A CN202410294985.7A CN202410294985A CN118022561A CN 118022561 A CN118022561 A CN 118022561A CN 202410294985 A CN202410294985 A CN 202410294985A CN 118022561 A CN118022561 A CN 118022561A
- Authority
- CN
- China
- Prior art keywords
- film
- graphene oxide
- graphene
- hydrogel
- selective 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.)
- Pending
Links
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 122
- 229910021389 graphene Inorganic materials 0.000 title claims abstract description 121
- 239000012528 membrane Substances 0.000 title claims abstract description 100
- 239000000017 hydrogel Substances 0.000 claims abstract description 85
- 239000004372 Polyvinyl alcohol Substances 0.000 claims abstract description 51
- 229920002451 polyvinyl alcohol Polymers 0.000 claims abstract description 51
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 37
- 239000000661 sodium alginate Substances 0.000 claims abstract description 31
- 229940005550 sodium alginate Drugs 0.000 claims abstract description 31
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 claims abstract description 26
- 235000010413 sodium alginate Nutrition 0.000 claims abstract description 26
- 239000007864 aqueous solution Substances 0.000 claims abstract description 19
- 229920000642 polymer Polymers 0.000 claims abstract description 13
- 238000005189 flocculation Methods 0.000 claims abstract description 7
- 230000016615 flocculation Effects 0.000 claims abstract description 7
- 238000002156 mixing Methods 0.000 claims abstract description 7
- 239000011248 coating agent Substances 0.000 claims abstract description 5
- 238000000576 coating method Methods 0.000 claims abstract description 5
- 238000013329 compounding Methods 0.000 claims abstract description 3
- 239000010408 film Substances 0.000 claims description 149
- 150000002500 ions Chemical class 0.000 claims description 73
- 239000000243 solution Substances 0.000 claims description 33
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 32
- 239000000499 gel Substances 0.000 claims description 23
- 238000000034 method Methods 0.000 claims description 20
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 claims description 11
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 claims description 11
- 238000000137 annealing Methods 0.000 claims description 10
- 238000001035 drying Methods 0.000 claims description 10
- 239000011259 mixed solution Substances 0.000 claims description 10
- 239000008367 deionised water Substances 0.000 claims description 9
- 229910021641 deionized water Inorganic materials 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 7
- SXRSQZLOMIGNAQ-UHFFFAOYSA-N Glutaraldehyde Chemical group O=CCCCC=O SXRSQZLOMIGNAQ-UHFFFAOYSA-N 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 238000010345 tape casting Methods 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 4
- 239000003431 cross linking reagent Substances 0.000 claims description 4
- 238000000909 electrodialysis Methods 0.000 claims description 4
- 230000002441 reversible effect Effects 0.000 claims description 4
- 239000010409 thin film Substances 0.000 claims description 4
- 239000001257 hydrogen Substances 0.000 abstract description 8
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 8
- 239000011229 interlayer Substances 0.000 abstract description 8
- 229920002554 vinyl polymer Polymers 0.000 abstract description 5
- 239000002131 composite material Substances 0.000 abstract description 4
- 230000008961 swelling Effects 0.000 abstract description 3
- 238000012360 testing method Methods 0.000 description 23
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 19
- 230000000052 comparative effect Effects 0.000 description 18
- 239000010410 layer Substances 0.000 description 15
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 10
- 230000035699 permeability Effects 0.000 description 9
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 8
- 239000011148 porous material Substances 0.000 description 7
- 239000000843 powder Substances 0.000 description 7
- 239000012266 salt solution Substances 0.000 description 7
- 239000002002 slurry Substances 0.000 description 6
- 239000011780 sodium chloride Substances 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 230000037427 ion transport Effects 0.000 description 5
- 239000001103 potassium chloride Substances 0.000 description 5
- 235000011164 potassium chloride Nutrition 0.000 description 5
- 238000002791 soaking Methods 0.000 description 5
- 230000003993 interaction Effects 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 239000013535 sea water Substances 0.000 description 4
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 4
- 101150096185 PAAS gene Proteins 0.000 description 3
- 150000007942 carboxylates Chemical class 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000002090 nanochannel Substances 0.000 description 3
- 239000002135 nanosheet Substances 0.000 description 3
- 230000003204 osmotic effect Effects 0.000 description 3
- 238000007790 scraping Methods 0.000 description 3
- 239000006228 supernatant Substances 0.000 description 3
- -1 AR) Chemical compound 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 150000001450 anions Chemical class 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 2
- 150000001768 cations Chemical class 0.000 description 2
- 229920002678 cellulose Polymers 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000007606 doctor blade method Methods 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000002086 nanomaterial Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000013049 sediment Substances 0.000 description 2
- 235000010344 sodium nitrate Nutrition 0.000 description 2
- 239000004317 sodium nitrate Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- 230000032895 transmembrane transport Effects 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 102100028292 Aladin Human genes 0.000 description 1
- 101710065039 Aladin Proteins 0.000 description 1
- 238000001157 Fourier transform infrared spectrum Methods 0.000 description 1
- 238000004566 IR spectroscopy Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000003373 anti-fouling effect Effects 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 238000002484 cyclic voltammetry Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 239000005457 ice water Substances 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 229920000831 ionic polymer Polymers 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- CSJDCSCTVDEHRN-UHFFFAOYSA-N methane;molecular oxygen Chemical compound C.O=O CSJDCSCTVDEHRN-UHFFFAOYSA-N 0.000 description 1
- 239000002064 nanoplatelet Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 235000011837 pasties Nutrition 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000002504 physiological saline solution Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000012286 potassium permanganate Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000001338 self-assembly Methods 0.000 description 1
- 238000000967 suction filtration Methods 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 238000009210 therapy by ultrasound Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
-
- 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
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/26—Polyalkenes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/24—Mechanical properties, e.g. strength
-
- 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
- B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
- B01D61/422—Electrodialysis
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
The invention discloses a reusable graphene-based ion selective membrane and application thereof. Comprises a graphene oxide film and a permeable hydrogel film; the permeable hydrogel film is made of crosslinked network hydrogel containing polyvinyl alcohol and sodium alginate; the graphene oxide film contains crosslinked network hydrogel, and has a micropore and mesoporous structure. Mixing a polymer aqueous solution containing-COO ‑ with a graphene oxide aqueous solution, adjusting the pH value until flocculation is generated, and centrifugally blade-coating to form a film; and compounding the crosslinked network hydrogel containing polyvinyl alcohol and sodium alginate with the graphene oxide film to obtain the graphene-based ion selective membrane. According to the invention, a small amount of polyvinyl alcohol-sodium alginate hydrogel enters the interlayer of the graphene oxide film and is connected through hydrogen bonds, so that the graphene oxide composite film can be effectively inhibited from swelling in water, and the hydrogel film can be torn off and repeatedly scraped so that the graphene oxide composite film can be reused.
Description
Technical Field
The invention relates to the technical field of ion selective membranes, in particular to a recyclable graphene-based ion selective membrane and application thereof.
Background
Renewable, cleanable osmotic energy is increasingly gaining in importance due to its large reserves and availability. It is present in fluids of different salinity gradients and can be readily collected by Reverse Electrodialysis (RED) systems. In the RED system, physiological saline solutions of different concentrations are separated by ion selective membranes. Anions and cations are separated by an ion-selective membrane under a concentration gradient, and gibbs free energy is converted to electrical energy. The maximum energy conversion efficiency of a single cation or anion selective membrane can even reach 50%, showing the advantage of the system in collecting osmotic energy. Ion selective membranes are a core component of RED.
The two-dimensional (2D) nanomaterial has the advantages of simplicity, strong expandability and the like, can be used for constructing an ion selective membrane, and is more suitable for large-scale application. By superposition of two-dimensional nanoplatelets, uniform and continuous nanofluidic channels can be easily formed. Graphene Oxide (GO) is a typical two-dimensional nanomaterial that can be easily obtained by mature fabrication techniques. However, the direction of the nanochannels in the layered structure is perpendicular to the desired transmembrane direction, and the twisted ion transport path within the nanochannels is several orders of magnitude longer than the membrane thickness, resulting in a very high membrane internal resistance. In addition, graphene oxide membranes are susceptible to swelling when exposed to aqueous solutions due to the abundance of hydrophilic groups, which can greatly impair the ion selectivity of the membrane. Therefore, many researches are carried out on preparing the graphene oxide film, and the graphene oxide film is prepared by mixing the graphene oxide film with substances such as hydrogel and the like, so that the problem that the graphene oxide film is easily swelled in water is solved. An electrochemical selective membrane for removing heavy metal ions in water, a preparation method and application thereof are disclosed in the patent with the application number of CN201510128904.7, and graphene oxide and hydrogel are mixed to prepare the selective membrane. However, the method can influence the permeability of the graphene oxide film, so that the pore structure in the film is greatly reduced, and the doping of the hydrogel can influence the electrochemical performance of the graphene oxide film, so that the effect of the graphene oxide film in reverse electrodialysis is further influenced. Moreover, in practical applications, all ion selective membranes containing graphene oxide membranes are susceptible to contamination and clogging with large ions. Therefore, there is an urgent need for a graphene-based ion-selective membrane capable of preventing graphene oxide from being easily swelled in water, so that the graphene-based ion-selective membrane can be reused, and the cost of RED is reduced.
Disclosure of Invention
In view of the above prior art, an object of the present invention is to provide a reusable graphene-based ion-selective membrane and application thereof. According to the invention, the graphene oxide film and the polyvinyl alcohol-sodium alginate hydrogel are compounded, so that a small amount of the polyvinyl alcohol-sodium alginate hydrogel enters the interlayer of the graphene oxide film and is connected through hydrogen bonds, the ion selectivity of the graphene oxide film is not affected, the graphene oxide is prevented from expanding in water, and the hydrogel film can be repeatedly prepared so that the graphene oxide film can be repeatedly used.
In order to achieve the above purpose, the invention adopts the following technical scheme:
In a first aspect of the invention, there is provided a reusable graphene-based ion-selective membrane comprising a graphene oxide thin film; at least one surface of the graphene oxide film is provided with a permeable hydrogel film; the hydrogel film is made of crosslinked network hydrogel, and the crosslinked network hydrogel is crosslinked network hydrogel containing polyvinyl alcohol and sodium alginate; the graphene oxide film contains crosslinked network hydrogel; the graphene oxide film is provided with a micropore and mesoporous structure.
Preferably, the graphene-based ion-selective membrane is prepared by the following method:
(1) Pouring a polymer aqueous solution containing-COO - into a graphene oxide aqueous solution, adjusting the pH value until flocculation is generated, centrifugally blade-coating to form a film, and then drying and annealing to obtain a graphene oxide film;
(2) And compositing the crosslinked network hydrogel containing polyvinyl alcohol and sodium alginate with at least one surface of the graphene oxide film, and drying at room temperature to obtain the reusable graphene-based ion selective membrane.
Preferably, in the step (1), the polymer aqueous solution containing-COO - is obtained by mixing a polymer containing-COO - with deionized water, and the concentration is 0.2 mg/mL; the polymer containing-COO - is sodium polyacrylate; the concentration of the graphene oxide aqueous solution is 1 mg/mL.
Preferably, the mass ratio of the polymer containing-COO - to the graphene oxide is 1:1.25; the pH value is adjusted by adding hydrochloric acid, and the concentration of the hydrochloric acid is 0.1M.
Preferably, in the step (1), the drying temperature is 40 ℃, and the drying time is 1h; the annealing temperature is 120 ℃, and the annealing time is 1h.
Preferably, in the step (2), the crosslinked network hydrogel containing polyvinyl alcohol and sodium alginate is prepared by the following method:
Adding polyvinyl alcohol and sodium alginate into water to obtain a mixed solution, heating to form a gel solution, cooling to room temperature, adding a crosslinking agent and an accelerator, and stirring to obtain the crosslinked network hydrogel containing the polyvinyl alcohol and the sodium alginate.
Preferably, the mass fraction of the polyvinyl alcohol in the mixed solution is 10%, and the concentration of sodium alginate is 0.1M; the heating temperature is 90 ℃, and the heating time is 1h.
Preferably, in the step (2), the cross-linking agent is glutaraldehyde solution; the accelerator is hydrochloric acid, and the concentration of the hydrochloric acid is 0.1M; the volume ratio of the gel solution, glutaraldehyde solution and hydrochloric acid is as follows: 10:0.25:0.1.
Preferably, in the step (2), the mass ratio of the polyvinyl alcohol to the graphene oxide contained in the graphene oxide film is (20-30): 1, a step of; the compounding is knife coating, pouring or immersing the graphene oxide film in crosslinked network hydrogel containing polyvinyl alcohol and sodium alginate.
In a second aspect of the invention there is provided the use of a reusable graphene-based ion-selective membrane in reverse electrodialysis.
The invention has the beneficial effects that:
(1) According to the invention, the graphene oxide film and the polyvinyl alcohol-sodium alginate hydrogel film are compounded, so that a small amount of polyvinyl alcohol-sodium alginate hydrogel enters the graphene oxide polymer composite film and is connected through hydrogen bonds, the ion selectivity of the graphene oxide film is not affected, the graphene oxide is prevented from expanding in water, the hydrogel film can be repeatedly prepared, the graphene oxide film can be repeatedly used, and the charge density of the ion selective film can be improved.
(2) The ion-selective membrane prepared by the method has excellent mechanical properties and stability due to the hydrogen bonding action between the polyvinyl alcohol and the graphene oxide. The synergistic effect of sodium polyacrylate and micro/mesoporous structure and sodium alginate makes the prepared film possess excellent ion selectivity and permeability.
(3) The preparation method is simple, the graphene oxide film in the ion selective membrane can be reused, and the RED cost is reduced.
Drawings
FIG. 1 a) SEM image of a cross section of a GPPS film, the gel layer being coloured to distinguish it from the GP-F layer; b) FT-IR spectra of graphene oxide, GP and GPPS films; c) Large area GPPS film (22 cm x 30 cm); d) XRD spectra of GP-F film and GPPS before and after soaking GP-F film; e) V-t curves for GPPS and GP-F films; f) The optical image of the GPPS film, PVA and SA are mixed into hydrogel after being soaked in water for a long time, and the gel on the GPPS film can fall off after long-term operation;
FIG. 2 a-c) pore size distribution of GP, GP-f and GPPS membranes;
FIG. 3 a) current-voltage curves for ion selective membranes of GP, GP-F, GP-F/PVA, GP-F/SA, GPPP, GPPS, GPPS-X and GPPS-Y at a concentration gradient of 0.5M/0.01M; b) The current-voltage (I-V) curves show open circuit Voltage (VOC) and short circuit current (ISC), and the calculated penetration potential (VOS) and current (IOS); c) Anti-fouling capability of GPPS films;
FIG. 4:a) maximum output power density of GPPS at different pH and b) different electrolytes; c) The osmotic energy of the mixture of the real river water (Jinan Xiaoqing river) and the sea water (yellow sea) to the GPPS membrane is collected;
Fig. 5: a) XPS map of GP-F film; b) XPS profile of GPPS membrane (without permeable hydrogel film); c) XPS profile of GPPS film;
Fig. 6: the XRD spectra before and after soaking were obtained by knife coating the GP film of the mixed hydrogel.
Detailed Description
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
As described in the background section, graphene oxide films are ideal choices for controlling ion transport due to their layered structure. However, graphene oxide films readily swell in water. Annealing is generally used to improve the stability of the graphene oxide film in water, but the graphene oxide film still swells when used in water or salt solution later, and annealing reduces the carboxyl content and reduces ion selectivity.
Based on this, it is an object of the present invention to provide a reusable graphene-based ion-selective membrane. According to the preparation method, the graphene oxide film is prepared, based on the self-repulsive effect, graphene oxide nano sheets are horizontally arranged into a layered structure in a self-assembly process, and channels between adjacent nano sheets are formed to have specific interlayer spacing. The ion transmission paths are mutually wound in the horizontally stacked nano sheets and are perpendicular to the required flow direction passing through the membrane, and in order to accelerate the transmembrane transfer of ions, the regulation and control of the pore structure are realized through induced flocculation, so that the graphene oxide film with the micropore/mesoporous structure is obtained. The mesoporous structure can effectively shorten the ion transmembrane transport distance, thereby reducing the ion transmembrane transport resistance. Sodium polyacrylate to modify graphene oxide has multiple functions: the method can not only provide carboxylate radicals, but also form flocculation with graphene oxide so as to adjust the pore structure of the graphene oxide film, and can also cooperate with sodium alginate in hydrogel. Then, the invention prepares a permeable hydrogel film, PVA and SA are crosslinked to form hydrogel with a crosslinked network, then the hydrogel is coated on the graphene oxide film in a scraping way, part of the hydrogel enters the interlayer of the graphene oxide, and hydroxyl groups on the hydrogel and hydroxyl groups on the graphene oxide are combined through hydrogen bonds, so that the graphene oxide is not easy to expand due to the combining effect of the hydrogel when the permeable hydrogel film is used in water. The inventor researches show that if only PVA is added into the hydrogel, the hydrogel film cannot be peeled off from the graphene oxide film after the ion-selective film is used in water, and the selectivity and charge density of the ion-selective film can be reduced. A certain amount of SA is added into PVA, and after the PVA is used, the hydrogel film can be peeled off from the graphene oxide film. In addition, the addition amount of SA is also important, too much addition can cause the graphene oxide film to swell, and too little addition can cause the charge density of the ion-selective membrane to be insufficient; after SA is added into the hydrogel, carboxylate contained in the hydrogel can provide a certain charge density, and the carboxylate can cooperate with sodium polyacrylate and a pore structure to improve the ion selectivity and permeability of the ion selective membrane. The hydrogel film can prevent large pollutants such as large ions from entering the graphene oxide film, the hydrogel film can be torn off after the graphene oxide film is used in water or salt solution, PVA and SA are coated on the graphene oxide film in a scraping mode to form hydrogel with a crosslinked network through crosslinking, and a new ion selective membrane is formed, so that repeated use is achieved.
In order to enable those skilled in the art to more clearly understand the technical scheme of the present application, the technical scheme of the present application will be described in detail with reference to specific embodiments.
Description: the graphene oxide used in the invention is prepared by adopting an improved Hummer method, and the specific method comprises the following steps:
1. Low temperature stage (Ice water bath)
70ML of 98wt% concentrated sulfuric acid is added into a three-necked flask, 1.5g of sodium nitrate is added, stirring is carried out until the sodium nitrate is dissolved, 3g of graphite powder is added, and stirring is carried out for 30 min. 9g of potassium permanganate was slowly added to ensure an ice bath temperature of 0℃and stirred for one hour. The solution changed from black to greenish black.
2. Intermediate temperature stage
Hot water was poured and heated rapidly to 40 ℃ for reaction 30min.
3. High temperature stage
150 M L deionized water was added to the reaction system and the temperature was raised to 90 ℃ and stirring was continued for 15: 15 min, at which time the system was converted to a brown pasty mixture.
4. Cooling
Adding 3% hydrogen peroxide of 500mL ice, continuously and slowly adding, cooling to room temperature, and the slurry concentration is about 6 mg/mL
5. Washing
Standing overnight, layering, and pouring out supernatant. 5% diluted hydrochloric acid (60 mL concentrated hydrochloric acid+360 mL water) was prepared; adding the mixture into the slurry, stirring, and filtering to remove sulfate radical and permanganate ions. The same volume of deionized water is filtered once/twice. And (5) performing centrifugal washing once at 8000r with an equal volume, dispersing the bottom slurry into a concentrated solution, and storing in the upper layer of a refrigerator. Dialyzing for two weeks. Ultrasonic for half an hour at 30% power, and removing sediment at the rotating speed of a centrifugal machine of 3000r for 30 min; the supernatant was removed at a rotational speed of 10000r for 30min, and the remainder was the target product.
Hydrochloric acid (HCl, AR), sodium chloride (NaCl, AR), potassium chloride (KCl, 99.5%) and lithium chloride (LiCl, AR) were purchased from Ron reagents.
Sodium polyacrylate (molecular weight 50000000-70000000, 99%) was purchased from Macklin; polyvinyl alcohol (PVA, molecular weight 13000-23000), sodium alginate (SA, molecular weight 5000000-7000000) are available from aladin; the above molecular weights are all average relative molecular weights.
The ion selective membrane of the invention is a dry membrane (dry) before soaking and a wet membrane (wet) after soaking.
All chemicals were used as received.
The test materials used in the examples of the present invention are all conventional in the art and are commercially available.
Examples: preparation of graphene oxide-based ion selective membrane with microporous mesoporous structure and capable of being prepared in large area
(1) 0.2 G sodium polyacrylate (PAAS, 99%) was dissolved in 1L deionized water and mixed well to obtain sodium polyacrylate aqueous solution. Dispersing 100 mg graphene oxide in 100 mL deionized water, and performing ultrasonic treatment on 1h to obtain a uniformly mixed graphene oxide aqueous solution.
(2) And (3) fully mixing 32mL of the sodium polyacrylate aqueous solution obtained in the step (1) with 8mL of the graphene oxide aqueous solution, adding 0.1M hydrochloric acid solution to adjust the pH to 3, and standing for 1h to obtain a flocculation-containing GP-F mixed solution. Centrifuging the mixed solution, pouring out the supernatant, then scraping the slurry on cellulose ester membrane filter paper (aperture 200 nm) to form a membrane, putting the membrane into an oven, and drying at 40 ℃ for 1: 1h, thereby ensuring that the water in the membrane slowly escapes. Annealing in an oven at 120℃for 1 hour will give GP-F films.
(3) PVA powder and sodium alginate powder are added into deionized water, the mass fraction of PVA in the solution is 10%, the concentration of sodium alginate is 0.1M, the solution is heated at 90 ℃ for 1h to obtain hydrogel solution, 10mL of hydrogel solution is taken, 250 mu L of glutaraldehyde and 100 mu L of 0.1M hydrochloric acid solution are sequentially added, mixed hydrogel is obtained after stirring for 1h, 2mL of mixed hydrogel is taken to be scraped on one surface of a GP-F membrane, and the ion selective membrane (GPPS membrane) with a micropore/mesopore structure and capable of being prepared in a large area is obtained after drying at room temperature.
Characterization: since graphene oxide films are easily swelled in water, an annealing method is employed to enhance stability. The ionic polymer PAAS is also used to increase the surface charge density and ion selectivity of graphene oxide based membranes. Unlike the usual use of well-dispersed graphene oxide solutions, the pH of the GO/PAAS mixed solution is adjusted and the resulting floccules are used to make membranes. When the pH of the mixed solution is adjusted to 3, the stability of the colloidal solution is deteriorated under acidic conditions, and flocs appear. The flocculated solution was concentrated by centrifugation to a slurry. The slurry can be used for preparing large-area GP-F films by a knife coating method. GPPS was then prepared by knife coating the PVA/SA solution onto GP-F. FIG. 1a is a cross section of a GPPS film wherein a GP-F film having a thickness of 8.5 μm is adhered to a PVA/SA hydrogel film having a thickness of about 7.4. Mu.m. Part of the PVA/SA gel penetrated into the GP-F layer, which is consistent with XPS data (see FIG. 5), and the C/O ratio of the film was reduced after coating the PVA/SA gel layer. In the GPPS film, the carbon-oxygen ratio on the gel side is slightly higher than on the non-gel side. This indicates that PVA/SA penetrated the GP-F film and FI-IR spectroscopy confirmed that hydrogen bonds were formed between the graphene film and the hydrogel. The peak around 1630cm −1 is the characteristic absorption peak of carboxylate. The red shift of the GPPS film compared to the O-H absorption peak of graphene oxide and GP film at 3450 cm −1 suggests that hydrogen bonds are formed between GP-F film and hydrogel (fig. 1 b). Due to the strong hydrogen bond interactions, GO and PVA are tightly bound so that a large area graphene oxide based ion selective membrane can be prepared (fig. 1 c).
Comparative example 1
The difference from the examples is that: and directly carrying out suction filtration on the mixed solution of the sodium polyacrylate aqueous solution and the graphene oxide aqueous solution without adjusting the pH value to flocculation to obtain a compact graphene oxide composite membrane, thereby obtaining the GP membrane.
Comparative example 2
The difference from the examples is that: the surface of the GP-F film is not coated with hydrogel, and the GP-F film is obtained.
The structural difference of the GP-F film prepared in comparative example 2 and the GP film prepared in comparative example 1 was compared: the pore size of GP membranes is less than 5 nm (fig. 2 a) and is relatively concentrated, whereas the pore size of GP-F membranes is widely distributed between 2-20 nm (fig. 2 b). Thus confirming the successful construction of the mesoporous structure in GP-F membranes.
Due to the mesoporous structure, the gel can easily penetrate into the middle layer of the GP-F membrane. Thus, compared to GP-F films, some of the mesopores in the GPPS films prepared in the examples disappeared (fig. 2 c), but still had a microporous and mesoporous structure. The interpenetration gel layer has an important influence on the interlayer spacing and stability of the GPPS film. As shown in FIG. 1d, the interlayer spacing of the GP-F film (dry film) was 0.83 nm, the GPPS film was prepared by doctor blade coating of hydrogel on the GP-F film, the hydrogel was introduced into the GP-F film after doctor blade coating, and the interlayer spacing of the GP-F film (dry film) in the GPPS film was changed to 0.98 nm, indicating that gel molecules were introduced into the interlayer spacing of the GP-F film. The GP-F film swells from 0.83 nm to 1.48 nm after soaking for 6 hours due to the rich hydrophilic groups, indicating that the GP-F film has instability in water. After the hydrogel was scraped, the GPPS film had a GP-F film layer spacing of 0.98 nm and a GP-F film layer spacing of 1.02 nm after 6h of immersion. This suggests that coating PVA hydrogel can effectively inhibit the swelling behaviour of GP-F membrane (fig. 1 d). If the mesoporous structure is not present, the mixed hydrogel prepared in the step (3) of the example is knife coated on the GP film prepared in the step (1) of the comparative example to obtain the ion selective film containing the hydrogel film, and since PVA/SA molecules cannot penetrate into the nanochannels of the GP film, the layer spacing of the GP film after immersing the ion selective film (hydrogel film+gp film) is greatly changed, and as can be seen from fig. 6, the layer spacing of the GP film coated with the mixed hydrogel is 0.77 nm when the GP film is not immersed, and the layer spacing thereof is increased to 1.1 nm after immersing for 6 hours, which indicates that the stability of the GP film in an aqueous solution is poor. From fig. 1e it can be seen that the effect between PVA hydrogel and graphene can make GPPS films more stable than GP-F films. If only PVA gel (no SA added) is coated on the GP-F film, the PVA gel and the GP-F film are tightly adhered together. When ionic SA is mixed with PVA as a hydrogel, some of the binding sites of PVA-GO are replaced by SA-GO. Due to the strong interaction between water molecules and the carboxyl groups of the SA, water molecules can disrupt the interaction between SA and GO. Thus, in the wet state, the presence of SA molecules weakens the strong interaction between PVA and GP-F, and the PVA/SA gel can be peeled off from the GP-F film after prolonged operation (FIG. 1F). In practice, therefore, the gel layer can serve to block potential contaminants and can be substituted to inhibit deterioration of the membrane performance due to contamination and clogging.
Comparative example 3
The difference from the examples is that: in the step (3), no SA powder is added, and only PVA hydrogel is scraped on the surface of the GP-F film to obtain the GP-F/PVA film.
Comparative example 4
The difference from the examples is that: in the step (3), PVA powder is not added, and only SA hydrogel is scraped on the surface of the GP-F film, so that the GP-F/SA film is obtained.
Comparative example 5
The difference from the examples is that: in the step (3), the addition amount of the SA powder was reduced to a concentration of 0.05M. Finally, the GPPS-X film is prepared.
Comparative example 6
(1) Step (1) of the same embodiment.
(2) And (3) fully mixing 32mL of the sodium polyacrylate aqueous solution obtained in the step (1) with 8mL of the graphene oxide aqueous solution to obtain a mixed solution.
(3) PVA powder (13000-23000) and sodium alginate powder (5000000-7000000) are added into the solution (2) to enable the mass fraction of PVA in the solution to be 10% and the concentration of sodium alginate to be 0.1M, the solution is heated at 90 ℃ for 1h to obtain graphene oxide polymer hydrogel solution, 10mL of gel solution is taken and sequentially added, 250 mu L of glutaraldehyde and 100 mu L of 0.1M of hydrochloric acid solution are stirred for 1min to obtain mixed hydrogel, 2mL of gel is scraped on a glass plate, and the mixed hydrogel is dried at room temperature to obtain the GPPS-Y film.
Test example 1: transmembrane ion transport properties.
(1) The potentials of the ion-selective membranes prepared in examples and comparative examples 1 to 6 were measured by using a zeta potentiometer (model: JS94H 2), and the obtained results are shown in Table 1.
TABLE 1
The greater the absolute value of the zeta potential, the higher the charge density of the film, which is advantageous for ion selectivity improvement. As can be seen from table 1, the ion-selective membranes prepared in the examples have the highest potential (absolute value).
(2) A membrane radius of 7.5cm was obtained by dissolving a 0.5M sodium chloride salt solution in 1000ml deionized water with 29.22g NaCl to simulate seawater. 0.01 M sodium chloride salt solution was prepared by dissolving 0.5844g NaCl in 1000ml deionized water to simulate river water.
Ion transport properties and energy conversion tests were measured using an electrochemical workstation (CHI 760E B18569). In the test process, GPPS prepared in the example is adhered on a cellulose ester film (aperture, 200 μm), a test area is controlled by punching a PI film, the area of the hole is adjusted to the required test area, and the size of the hole is the actual test area. The ion-selective membranes prepared in comparative examples 1 to 6 were subjected to the same treatment in this way. The ion selective membranes prepared in examples and comparative examples 1 to 6 were respectively sandwiched between two chambers of a test cell (a replaceable membrane H-type cell CH 2010H-type frosted port cell), the two chambers respectively contained 0.5M saline solution and 0.01M saline solution, the above devices were connected to an electrochemical workstation, and an I-V curve was recorded using cyclic voltammetry, with a scan voltage range of-0.3V to +0.3V, and a step voltage of 0.001V. The redox potential imbalance at the electrolyte interface was eliminated using a saturated potassium chloride bridge and the voltage measured was the diffusion potential (see figure 3 a).
The I-V curve obtained by the GPPS membrane in fig. 3b has the largest area surrounded by the X-axis and the Y-axis, which indicates that the GPPS membrane has the largest output power density, and the X-axis indicates the voltage level, which can indirectly reflect the selectivity of the ionic membrane, and the higher the voltage, the higher the selectivity of the ionic membrane and the better the permeability.
The effect between PVA hydrogel and graphene can make GPPS films more stable than GP-F films. The inverse of the slope of the curve in fig. 3b indicates the resistance, and the resistance of the film decreases but the selectivity of the film decreases after doctor blading the gel. Therefore, the sodium alginate is added to increase the charge density of the surface of the membrane, and the GPPS membrane added with the sodium alginate can reduce the resistance of the membrane and improve the selectivity of the membrane. The sodium alginate, the mesoporous structure and the polyvinyl alcohol have obvious synergistic effect, so that the ion selectivity can be improved, and the resistance of the membrane can be reduced.
(3) After the test, the ion-selective membranes prepared in examples and comparative examples 1 to 6 were taken out, and the permeable hydrogel film was removed. Wherein the graphene oxide thin films in the ion-selective membranes prepared in comparative examples 1,2 and 4 are severely swollen and cannot be reused; the ion-selective membrane prepared in comparative example 3 could not peel off the permeable hydrogel film, nor could it be reused; comparative example 6 is a film prepared by mixing graphene oxide with hydrogel, and the hydrogel cannot be peeled off and reused.
Only the GPPS ion-selective membranes prepared in examples and comparative example 5 can remove the permeable hydrogel film. However, the film of comparative example 5 has poor ion-transport properties with lower ion selectivity and GPPS voltage and zeta potential than GPPS film (see fig. 3b and table 1), and the graphene oxide film is difficult to reuse.
The GPPS membrane prepared in the example was subjected to a long-time test, after which the gel on the membrane surface was peeled off, and then a permeable hydrogel membrane was prepared again on the graphene oxide membrane according to the method of example step (3), to obtain a new ion-selective membrane. The energy conversion test was performed again according to the method in test example (1). The above method was repeated 5 times in total, and as shown in fig. 3c, the output voltage of the film was measured at the time of repeatedly peeling off the gel layer, and the output voltage of the film was not significantly attenuated in the first four cycles. Particularly in the first cycle, the film exhibits excellent long-term stability when the gel layer is not peeled off.
Test example 2
1) 0.5M and 0.01M sodium chloride salt solutions with pH values of 3, 7, 9 and 11 are respectively prepared, and the sodium chloride salt solutions with the same pH value are respectively placed in two chambers of a test electrolytic cell, and the permeability of the GPPS ionic membrane prepared in the example is tested according to the method of test example 1. As can be seen from fig. 4a, the sodium chloride salt solution at 50-fold concentration gradient had the highest permeability of GPPS ion membrane at pH 11.
2) Lithium chloride solution, sodium chloride solution and potassium chloride solution of 0.5M and 0.01M were prepared, respectively, and lithium chloride solution of 0.5M and 0.01M were placed in two chambers of a test cell, sodium chloride solution of 0.5M and 0.01M were placed in two chambers of a test cell, and potassium chloride solution of 0.5M and 0.01M were placed in two chambers of a test cell according to the method of test example 1, and the permeability of the GPPS ion membrane prepared in the test example was tested. As can be seen from fig. 4b, the GPPS ion membrane prepared in example 1 has the highest permeability collection capacity for potassium chloride.
3) 100ML of small fresh river water (from Jinan small fresh river board bridge wharf) and yellow sea water (from China Japanese-shiny-ten-thousand plain seashore scenic spots) are taken, sediment is filtered by a Buchner funnel respectively, the filtered sea water is placed in a high-concentration chamber of a test electrolytic cell, the filtered river water is placed in a low-concentration chamber of the test electrolytic cell, and the permeability of the GPPS ionic membrane prepared in the example is tested according to the method of test example 1. As can be seen from fig. 4c, the GPPS ion membrane prepared in the example has excellent permeation performance.
The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (10)
1. A reusable graphene-based ion selective membrane, comprising a graphene oxide thin film; at least one surface of the graphene oxide film is provided with a permeable hydrogel film; the hydrogel film is made of crosslinked network hydrogel, and the crosslinked network hydrogel is crosslinked network hydrogel containing polyvinyl alcohol and sodium alginate; the graphene oxide film contains crosslinked network hydrogel; the graphene oxide film is provided with a micropore and mesoporous structure.
2. The graphene-based ion-selective membrane according to claim 1, prepared by the following method:
(1) Pouring a polymer aqueous solution containing-COO - into a graphene oxide aqueous solution, adjusting the pH value until flocculation is generated, centrifugally blade-coating to form a film, and then drying and annealing to obtain a graphene oxide film;
(2) And compositing the crosslinked network hydrogel containing polyvinyl alcohol and sodium alginate with at least one surface of the graphene oxide film, and drying at room temperature to obtain the reusable graphene-based ion selective membrane.
3. The graphene-based ion-selective membrane according to claim 2, wherein in step (1), the aqueous polymer solution containing-COO - is obtained by mixing a polymer containing-COO - with deionized water, and the concentration is 0.2 mg/mL; the polymer containing-COO - is sodium polyacrylate; the concentration of the graphene oxide aqueous solution is 1 mg/mL.
4. The graphene-based ion-selective membrane according to claim 3, wherein the mass ratio of the polymer containing-COO - to graphene oxide is 0.8:1, a step of; the pH value is adjusted by adding hydrochloric acid, and the concentration of the hydrochloric acid is 0.1M.
5. The graphene-based ion selective membrane according to claim 2, wherein in step (1), the drying temperature is 40 ℃ and the drying time is 1h; the annealing temperature is 120 ℃, and the annealing time is 1h.
6. The graphene-based ion-selective membrane according to claim 1, wherein in step (2), the crosslinked network hydrogel containing polyvinyl alcohol and sodium alginate is prepared by the following method:
Adding polyvinyl alcohol and sodium alginate into water to obtain a mixed solution, heating to form a gel solution, cooling to room temperature, adding a crosslinking agent and an accelerator, and stirring to obtain the crosslinked network hydrogel containing the polyvinyl alcohol and the sodium alginate.
7. The graphene-based ion selective membrane according to claim 6, wherein the mass fraction of polyvinyl alcohol in the mixed solution is 10%, and the concentration of sodium alginate is 0.1M; the heating temperature is 90 ℃, and the heating time is 1h.
8. The graphene-based ion-selective membrane according to claim 6, wherein in step (2), the cross-linking agent is glutaraldehyde solution; the accelerator is hydrochloric acid, and the concentration of the hydrochloric acid is 0.1M; the volume ratio of the gel solution, glutaraldehyde solution and hydrochloric acid is as follows: 10:0.25:0.1.
9. The graphene-based ion selective membrane according to claim 2, wherein in the step (2), the mass ratio of the polyvinyl alcohol to graphene oxide contained in the graphene oxide thin film is (20 to 30): 1, a step of; the compounding is knife coating, pouring or immersing the graphene oxide film in crosslinked network hydrogel containing polyvinyl alcohol and sodium alginate.
10. Use of the reusable graphene-based ion-selective membrane according to any one of claims 1 to 9 in reverse electrodialysis.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410294985.7A CN118022561A (en) | 2024-03-15 | 2024-03-15 | Reusable graphene-based ion selective membrane and application thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410294985.7A CN118022561A (en) | 2024-03-15 | 2024-03-15 | Reusable graphene-based ion selective membrane and application thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN118022561A true CN118022561A (en) | 2024-05-14 |
Family
ID=91002321
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410294985.7A Pending CN118022561A (en) | 2024-03-15 | 2024-03-15 | Reusable graphene-based ion selective membrane and application thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN118022561A (en) |
-
2024
- 2024-03-15 CN CN202410294985.7A patent/CN118022561A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Su et al. | Orientated graphene oxide/Nafion ultra-thin layer coated composite membranes for vanadium redox flow battery | |
| Hong et al. | Evaluation of electrochemical properties and reverse electrodialysis performance for porous cation exchange membranes with sulfate-functionalized iron oxide | |
| Tufa et al. | Salinity gradient power reverse electrodialysis: Cation exchange membrane design based on polypyrrole-chitosan composites for enhanced monovalent selectivity | |
| CN103446899B (en) | Organic and inorganic surface chemically-crosslinked alginate-based hybrid hydrogel filter membrane, and preparation method thereof | |
| US10807888B2 (en) | Carbon electrodes based capacitive deionization for the desalination of water | |
| US20190282969A1 (en) | Graphene Oxide Membrane With A Controllable Interlayer Spacing, A Preparation Method And Use Thereof | |
| Cao et al. | Hydrophilic poly (vinylidene fluoride) porous membrane with well connected ion transport networks for vanadium flow battery | |
| Hong et al. | Effect of inorganic filler size on electrochemical performance of nanocomposite cation exchange membranes for salinity gradient power generation | |
| JP5750604B2 (en) | Membrane for redox flow battery and method for producing the same | |
| WO2019139542A1 (en) | A graphene-based membrane | |
| CN104841287B (en) | A kind of preparation method of multi-functional graduation oil-water separation composite film material | |
| CN114669199B (en) | Modified mica sheet-nanocellulose composite nanofiltration membrane and preparation method thereof | |
| Koo et al. | Selective ion transport through three-dimensionally interconnected nanopores of quaternized block copolymer membranes for energy harvesting application | |
| Wang et al. | Advancing osmotic power generation using bioinspired MXene-based membrane via maze breaking | |
| CN118022561A (en) | Reusable graphene-based ion selective membrane and application thereof | |
| CN110756067B (en) | Preparation method and application of graphene oxide-based two-dimensional composite membrane embedded with sulfonated polymer cross-linked network | |
| CN114405286A (en) | Ion-crosslinked amphoteric ion exchange membrane, preparation method and application thereof in selective electrodialysis | |
| CN115181334B (en) | Bacterial cellulose-based salt difference energy composite hydrogel film material and preparation method and application thereof | |
| CN110292864A (en) | A kind of preparation method of composite nano materials hybridized film and the hybridized film thus prepared | |
| CN114713295B (en) | Monovalent selective cation exchange membrane and preparation method and application thereof | |
| Niu et al. | An anionic polyethersulfone membrane modified by poly (2-acrylamide-2-methylpropanesulfonic acid sodium salt) grafted carbon nanotubes | |
| Zhang et al. | Investigation of a novel high-efficiency ion-permselective membrane module based on the electrochemically switched ion exchange scheme | |
| CN115253729B (en) | Sulfonated nanocellulose/sulfonated polysulfone composite membrane and preparation method and application thereof | |
| CN116020264B (en) | Method for improving ultrafiltration membrane into nanofiltration membrane | |
| US20230226499A1 (en) | Ion-Selective Composite Membrane |
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 |