CN114247305B - Two-dimensional nano island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane and preparation method thereof - Google Patents
Two-dimensional nano island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane and preparation method thereof Download PDFInfo
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D71/06—Organic material
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- Y02A20/131—Reverse-osmosis
Abstract
The invention belongs to the technical field of nano membrane materials, and particularly relates to a two-dimensional nano island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane and a preparation method thereof. The invention also provides application of the two-dimensional nanometer island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane in water treatment. According to the two-dimensional nano island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane, various hydration ions (comprising K) can be effectively blocked by constructing hydrophobic pore channels with the interlayer spacing below 1nm and controllable angstrom level in the nanofiltration membrane + 、Na + 、Li + 、Ca 2+ 、Mg 2+ Etc.), ultra-high water flux can be obtained through extremely large capillary force in the two-dimensional nanometer limited area, thereby effectively improving the ion blocking rate and the water flux, greatly improving the water treatment efficiency and reducing the energy consumption of the water treatment membrane when applied to occasions such as sea water desalination, urban sewage treatment and the like.
Description
Technical Field
The invention belongs to the technical field of nano membrane materials, and particularly relates to a two-dimensional nano island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane and a preparation method thereof.
Background
Compared with the traditional distillation method, the method for purifying water by using the water treatment membrane technology has the advantages of high impurity separation efficiency, lower energy consumption in the treatment process, controllable cost and the like, and has wide application in the fields of sea water desalination, household water purification, industrial wastewater treatment and the like. Along with the development of water treatment membrane technology, different application fields put forward higher requirements on water treatment efficiency and energy loss reduction in the water treatment process, so that development of novel water treatment membrane technology capable of simultaneously achieving high water flux and high ion barrier property is urgently needed.
At present, the water treatment membranes are mainly divided into four types of microfiltration membranes (0.1-10 mu m), ultrafiltration membranes (10-100 nm), nanofiltration membranes (1-10 nm) and reverse osmosis membranes (0.1-1 nm) according to the size of the inner holes in the membranes. As the pore size in the membrane decreases, the water is purified to an increasing extent. The method is characterized in that most suspended particles, microorganisms and the like can be removed by utilizing the microfiltration membrane; most of high polymers and viruses can be removed by utilizing the ultrafiltration membrane; most of small organic molecules and divalent ions can be removed by utilizing the nanofiltration membrane; while substantially all ions, including monovalent alkali metal ions, can be removed using reverse osmosis membranes.
Meanwhile, the water with high purity is obtained by purification, and one or more reverse osmosis processes are generally carried out. Reverse osmosis membranes are typically made from polymeric materials, such as those currently commercially available, typically employ a Thin Film Composite (TFC), such as a polyamide membrane material. Because the reverse osmosis membrane utilizes the extremely small pore size to block monovalent ions and other impurities, and meanwhile, the extremely small pore size can also produce an obstruction effect on the permeation of water molecules, so that larger pressure (generally 10-60 bar) needs to be applied to the two sides of the membrane, the water molecules can pass through the reverse osmosis membrane by overcoming the osmotic pressure generated by concentration difference and the resistance generated by small pore size, and meanwhile, the impurities such as ions and the like are left, so that the effect of purifying water is achieved. In this process, a higher applied pressure means a greater energy loss in the water treatment process, while a smaller water flux (the speed of water molecules passing through the membrane) means a lower efficiency of the water treatment.
Unlike the reverse osmosis membrane, the nano-filtration membrane has slightly larger pore diameter, the pressure required to be applied on two sides of the nano-filtration membrane is far smaller than that of the reverse osmosis membrane (about 5-10 bar), and the water flux is relatively larger, but the defect is that the nano-filtration membrane has slightly larger pore diameter and has poorer blocking effect on monovalent ions.
Therefore, how to consider high water flux and high ion separation is the bottleneck problem in the field of water treatment membranes, and based on this, the application provides a two-dimensional nanometer island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane, and the structure of the nanofiltration membrane is improved so as to realize that ions in water are separated and simultaneously, the ultrahigh water flux can be obtained.
Disclosure of Invention
The invention aims at providing a two-dimensional nanometer island aiming at the defects existing in the prior artThe self-assembled hydrophobic nanofiltration membrane of the @ graphene heterojunction can effectively block various hydration ions (comprising K) by constructing hydrophobic pore channels with the interlayer spacing below 1nm and controllable angstrom level in the nanofiltration membrane + 、Na + 、Li + 、Ca 2+ 、Mg 2+ Etc.), can also obtain ultra-high water flux through extremely large capillary force in a two-dimensional nanometer limited domain, and effectively solve the bottleneck problem that the ion blocking rate and the water flux can not be improved at the same time.
The application also provides a preparation method of the two-dimensional nanometer island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
a hydrophobic two-dimensional nano-island @ graphene heterojunction material, wherein the two-dimensional nano-island structure may be, but is not limited to, ni-p-phenylenediamine hydrochloride (Ni-pPD), cu-p-phenylenediamine hydrochloride (Cu-pPD), ni-hexaaminobenzene (Ni-HAB), cu-hexaaminobenzene (Cu-HAB), graphite alkyne (GDY), cu-hexamercaptobenzene (Cu-BHT), or a two-dimensional covalent organic framework.
Specifically, the two-dimensional nano island material is grown on the surface of graphene through an oxygen group catalytic reaction, the hydrophobic two-dimensional nano island @ graphene heterojunction material is prepared, the graphene surface is not completely covered by the two-dimensional nano island material in the prepared heterojunction material, the graphene heterojunction material has a certain porosity, and the area ratio of the two-dimensional nano island material to the graphene is 10-70%.
Preferably, the area ratio of the two-dimensional nano islands to the graphene is 40-50%.
Specifically, in the prepared hydrophobic two-dimensional nano island@graphene heterojunction material, the contact angle of the two-dimensional nano island is 60-120 degrees, and the contact angle of the two-dimensional graphene is 60-90 degrees; preferably, the contact angle of the two-dimensional nano islands is 80-90 degrees.
Specifically, the invention also provides a preparation method of the hydrophobic two-dimensional nano island@graphene heterojunction material, which comprises the steps of adding graphene oxide suspension and soluble metal ions into a two-dimensional nano island precursor material aqueous solution, utilizing catalysis of oxygen groups on the surface of graphene oxide, growing into a two-dimensional nano island on the surface of the oxygen groups of the graphene oxide in situ, reducing the oxygen groups on the surface of the graphene oxide, and retaining the form of original graphene in a region without the oxygen groups on the surface of the graphene oxide, so as to prepare the two-dimensional nano island@graphene heterojunction material.
The preparation method comprises the following steps:
(1) Preparing a reaction solution: adding Graphene Oxide (GO) suspension into a soluble metal salt solution, and introducing inert gas to remove oxygen to obtain a solution A;
(2) Dissolving a two-dimensional nanometer island precursor material into water, and introducing inert gas to remove oxygen to obtain a solution B, so that the reaction of the two-dimensional nanometer island precursor material is ensured to be only carried out on the surface of an oxygen group of Graphene Oxide (GO);
(3) And adding the solution B into the solution A for oxygen radical catalytic reaction at the reaction temperature of-30-150 ℃ for 0.5-96 h, and performing suction filtration and washing to prepare the hydrophobic two-dimensional nano island@graphene heterojunction material.
Specifically, the soluble metal salt solution in the step (1) is a soluble metal salt solution of nickel or a soluble metal salt solution of copper.
Specifically, the concentration of the Graphene Oxide (GO) suspension in the step (1) is 0.1-5 mg/mL, preferably 0.2-1 mg/mL.
Specifically, the two-dimensional nanometer island precursor material in the step (2) is p-phenylenediamine hydrochloride, hexaaminobenzene, graphite alkyne or hexamercaptobenzene.
Specifically, the concentration of the solution B in the step (2) is 0.1 to 1mol/L, preferably 0.1 to 0.5mol/L.
Specifically, the inert gas used in the steps (1) and (2) is argon or nitrogen, and the inert gas is introduced for 0.1 to 24 hours, preferably 0.5 to 2 hours.
Specifically, the volume ratio of the solution B to the solution A in the step (3) is (0.1-10): 1.
specifically, the reaction is accelerated by stirring during the catalytic reaction of the oxygen group in the step (3), preferably by magnetic stirring, and the stirring rate is 10 to 1000rpm, preferably 300 to 500rpm.
Specifically, the temperature of the catalytic reaction of the oxygen group in the step (3) is preferably 10-110 ℃; the reaction time is preferably 5 to 20 hours.
Specifically, the suction filtration in the step (3) can be performed by normal pressure suction filtration or vacuum suction filtration, and the suction filtration time is 1-48 hours; the washing liquid used in the washing is deionized water or an organic solvent including, but not limited to, ethanol, acetone or methanol.
Specifically, the structure of the two-dimensional nano-island obtained in the step (3) may be, but is not limited to, ni-p-phenylenediamine hydrochloride (Ni-pPD), cu-p-phenylenediamine hydrochloride (Cu-pPD), ni-hexa-aminobenzene (Ni-HAB), cu-hexaaminobenzene (Cu-HAB), graphite alkyne (GDY), cu-hexa-mercapto benzene (Cu-BHT), or two-dimensional covalent organic framework.
Furthermore, the invention also provides an alternative method for preparing the hydrophobic two-dimensional nano island @ graphene heterojunction material, which is characterized in that only Graphene Oxide (GO) suspension is prepared in the step (1), and copper wires or silver wires are placed in the Graphene Oxide (GO) suspension to perform oxygen group catalytic reaction in the step (2).
Furthermore, the invention also provides application of the hydrophobic two-dimensional nano island@graphene heterojunction material in preparation of self-assembled hydrophobic nanofiltration membranes.
Further preferably, the invention also prepares the hydrophobic two-dimensional nano island @ graphene heterojunction material into a two-dimensional nano island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane by using a suction filtration mode.
Furthermore, the invention also discloses a preparation method of the two-dimensional nanometer island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane, which comprises the following steps:
a. preparing a pumping filtrate: preparing the hydrophobic two-dimensional nano island@graphene heterojunction material into a suspension;
b. suction filtration and drying: and d, placing the suspension in the step a on a substrate film, carrying out suction filtration, and then extruding the hydrophobic two-dimensional nano island@graphene heterojunction material in the suspension onto the substrate film under external pressure, and drying to obtain the two-dimensional nano island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane.
Further, in the step a, the concentration of the configured hydrophobic two-dimensional nano island@graphene heterojunction material suspension is 1-10 mg/mL, preferably 2-5 mg/mL.
Further, in the step b, the substrate film material includes, but is not limited to, polyethersulfone (PES), polystyrene (PS), mixed Cellulose Ester (MCE), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polycarbonate (PC), polypropylene (PP), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or porous alumina (AAO).
Further, in the step b, the pressure applied during the extrusion is in the range of 1 to 100N, preferably 5 to 20N.
In the step b, the drying is performed in a vacuum drying mode, and the drying temperature is 25-150 ℃, preferably 60-70 ℃; the drying time is 0.5 to 96 hours, preferably 10 to 12 hours; the vacuum degree used for drying is 1Pa to 1 atm, preferably 1Pa to 10Pa.
According to the two-dimensional nano island @ graphene heterojunction material self-assembled hydrophobic nanofiltration membrane constructed in a self-assembly mode by utilizing the hydrophobic two-dimensional nano island @ graphene heterojunction material, in the construction process, due to the hydrophobic effect, the two-dimensional nano island @ graphene heterojunction material self-assembles in an aqueous solution, so that the two-dimensional nano island is clamped between two layers of graphene to form a sub-nano interlayer, and thus the nanofiltration membrane with the inside rich in sub-nano hydrophobic pore canals is formed, and particularly, the inside of the nanofiltration membrane is rich in sub-nano hydrophobic pore canals, and the size of the hydrophobic pore canals is 0.1-1 nanometer.
The two-dimensional nanometer island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane prepared by the method provided by the invention is internally rich in sub-nanometer level hydrophobic pore canals, and hydration ions (comprising K + 、Na + 、Li + 、Ca 2+ 、Mg 2+ Etc.), and the extremely small hydrophobic pore canal can obtain ultra-high water flux through extremely large capillary force in the two-dimensional nanometer limited domain.
Furthermore, the invention also provides application of the two-dimensional nanometer island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane in water treatment, and particularly the water treatment is sea water desalination treatment, industrial wastewater treatment or municipal sewage treatment.
Furthermore, the invention also provides application of the two-dimensional nanometer island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane in adsorption separation of anions and cations in sewage.
Compared with the prior art, the invention has the advantages that:
1) The invention provides a preparation method of a two-dimensional nano island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane, which is different from a sub-nano hydrophilic pore or a larger-sized hydrophobic pore in a traditional water treatment membrane, and the nano filtration membrane prepared by the method is internally rich in the sub-nano hydrophobic pore. Due to the extremely small interlayer spacing and the hydrophobic pore canal, the novel nanofiltration membrane not only can effectively block various hydration ions (comprising K + 、Na + 、Li + 、Ca 2+ 、Mg 2+ And the like) and simultaneously can obtain ultrahigh water flux by utilizing extremely large capillary force in a hydrophobic two-dimensional nano limited domain, thereby effectively improving ion blocking and water flux and greatly improving water treatment efficiency, and further reducing energy consumption of the water treatment membrane technology in sea water desalination, industrial wastewater treatment, urban wastewater treatment and other applications.
2) Compared with a reverse osmosis membrane prepared by a Traditional Film Composite (TFC) polyamide membrane material, the nanofiltration membrane has larger pore diameter and is just suitable for blocking various hydration ions.
3) The internal pore canal of the water treatment membrane constructed by the two-dimensional Graphene Oxide (GO) or the composite material thereof is a hydrophilic pore canal, a large number of hydrophilic oxygen groups have an obstructing effect on the permeation of water molecules, and the smaller the pore diameter is, the larger the resistance is. Compared with a water treatment membrane constructed by two-dimensional Graphene Oxide (GO) or a composite material thereof, the pore canal of the nanofiltration membrane is a sub-nanometer level hydrophobic pore canal.
4) Although the two-dimensional water treatment membrane prepared by Reducing Graphene Oxide (RGO) or the traditional composite material has fewer oxygen groups on the surface, the water flux of the two-dimensional water treatment membrane is larger than the numerical value of the Graphene Oxide (GO) membrane, the two-dimensional RGO has the problem of re-stacking, so that the interlayer spacing between water treatment membrane layers constructed by the RGO is difficult to accurately control to sub-nanometer level, and the ion blocking effect of the two-dimensional water treatment membrane is affected. Compared with a water treatment membrane constructed by Reduced Graphene Oxide (RGO) or a traditional composite material thereof, the hydrophobic pore canal of the nanofiltration membrane is sub-nano-scale and fine and adjustable.
Drawings
Fig. 1 is a schematic structural diagram of a two-dimensional nano island @ graphene heterojunction material prepared by the methods of embodiments 1, 3 and 5 of the present invention, wherein fig. 1a is a side structure and an atomic structure, and fig. 1b is a surface structure;
fig. 2 is a schematic structural diagram of a two-dimensional nano island @ graphene heterojunction self-contained filter membrane prepared by the method of embodiments 2, 4 and 6 of the present invention, wherein the part encircled in fig. 2 is a sub-nano hydrophobic pore channel formed by stacking suspended parts;
FIG. 3 is a front side transmission electron microscope atomic micrograph of the two-dimensional Ni-p-phenylenediamine hydrochloride nanoisland @ graphene heterojunction material obtained in example 1;
fig. 4 is a two-dimensional Ni-p-phenylenediamine hydrochloride nano island @ graphene heterojunction self-assembled filter membrane section transmission electron microscope atomic micrograph obtained in example 2, wherein fig. 4a is a heterojunction section part diagram, fig. 4b is an enlarged view of the heterojunction section part, sub-nano hydrophobic pore channels can be seen, and the inset in fig. 4b is a heterojunction section atomic structure diagram;
fig. 5 is a graph showing the contact angle test of the two-dimensional Ni-p-phenylenediamine hydrochloride nano island @ graphene heterojunction self-assembled nanofiltration membrane obtained in example 2, fig. 5a shows the contact angle test result, and fig. 5b shows the photograph of the nanofiltration membrane.
Detailed Description
The invention will be further illustrated by the following examples in conjunction with the accompanying drawings. The embodiment is implemented on the premise of the technical scheme of the invention, and detailed implementation modes and processes are given, but the protection scope of the invention is not limited to the following embodiment.
In the following examples, two-dimensional nano island @ graphene heterojunction materials are constructed by adopting different two-dimensional nano island materials, and self-assembled into a hydrophobic nanofiltration membrane. The experimental methods in which specific conditions are not specified in the following examples are generally carried out under conventional conditions, and the raw materials and reagents used are commercially available products without any particular explanation.
Example 1
The two-dimensional nano islands adopted in the embodiment 1 are Ni-p-phenylenediamine hydrochloride (Ni-pPD) metal organic materials, and a two-dimensional Ni-p-phenylenediamine hydrochloride nano island @ graphene heterojunction material is constructed, and the two-dimensional Ni-p-phenylenediamine hydrochloride nano island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane is prepared based on the embodiment 2.
A preparation method of a two-dimensional Ni-p-phenylenediamine hydrochloride (Ni-pPD) nanometer island @ graphene heterojunction material comprises the following specific steps:
(1) 1.9 g of nickel nitrate (NiNO 3 ) Adding into 16mL deionized water, stirring for dissolving, and adding 32mL GO suspension with concentration of 5mg/mL (GO suspension is prepared by adopting a traditional Hummer's Method or can be purchased from a commercial finished product), introducing argon while stirring, and introducing for 2h to remove air in the solution to obtain solution A;
(2) Adding 2.0 g of p-phenylenediamine hydrochloride (pPD) which is commercially available sigma medicines and has the purity of more than 99 percent (chemical purity) into 60ml of deionized water, stirring and dissolving in a magnetic stirring mode, stirring at 400rpm, introducing argon while stirring, and introducing air for 2 hours to remove air in the solution, so as to obtain a solution B (two-dimensional nano island precursor material aqueous solution);
(3) Adding the solution B into the solution A, gradually adding ammonia water with the total volume of 20ml, and carrying out oxygen radical catalytic reaction at the reaction temperature of 40 ℃ for 20 hours; after the reaction is finished, pouring the reaction solution into a suction filtration bottle for suction filtration, firstly, performing suction filtration by using deionized water, then performing suction filtration by using ethanol, finally, performing suction filtration by using deionized water, performing suction filtration for 2 hours, and washing to obtain the two-dimensional Ni-p-phenylenediamine hydrochloride (Ni-pPD) nano island@graphene heterojunction material. Wherein, the area ratio of the two-dimensional Ni-p-phenylenediamine hydrochloride (Ni-pPD) nanometer island to the graphene is 40-50%.
Example 2
A preparation method of a two-dimensional Ni-p-phenylenediamine hydrochloride (Ni-pPD) nano island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane comprises the following specific steps:
a. weighing the two-dimensional Ni-p-phenylenediamine hydrochloride nano island@graphene heterojunction material, dispersing the material into deionized water, preparing heterojunction suspension with the dispersity of 2mg/mL, and then performing ultrasonic dispersion for 1h;
b. according to the thickness of the nanofiltration membrane to be prepared, dripping the suspension on a polyether sulfone (PES) substrate membrane (the PES substrate membrane is a porous substrate membrane prepared by PES materials and is also a standard substrate of standard materials, and can be purchased commercially, and the specification used in the implementation is phi 50mm aperture 0.22um and membrane thickness 110 micrometers), and carrying out suction filtration for 2 hours; after the suction filtration is finished, the polyethersulfone containing suspension is placed in two glass sheets, the pressure of 20N is applied to extrude the polyethersulfone, then the polyethersulfone is dried in vacuum at the temperature of 70 ℃, the vacuum degree is 10Pa, after the drying is finished, the glass sheets are opened at normal temperature, the two-dimensional Ni-p-phenylenediamine hydrochloride (Ni-pPD) nano island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane is obtained, the mass of the nanofiltration membrane is 1 mg-20 mg, and the thickness of the nanofiltration membrane is 5-50 microns.
The invention firstly provides a simple and effective method, which generates another hydrophobic two-dimensional nanometer island material by in-situ reaction at the oxygen group on the surface of two-dimensional graphene oxide through oxygen group catalytic reaction, and reduces the oxygen group on the two-dimensional graphene oxide to prepare a novel heterostructure material of the hydrophobic two-dimensional nanometer island @ graphene, the structure of which is shown in figure 1. According to the invention, the two-dimensional nanometer island @ graphene heterojunction material is subjected to self-assembly in an aqueous solution by further utilizing the hydrophobic effect, so that a structure that the two-dimensional nanometer island is clamped between two layers of graphene is obtained, the two-dimensional nanometer island can be used as a sub-nanometer interlayer of a two-dimensional water treatment film, and a nanofiltration film rich in sub-nanometer level hydrophobic pore channels is formed by bonding, and the structure is shown in figure 2.
Fig. 3 is a front side transmission electron microscope atomic micrograph of the two-dimensional Ni-p-phenylenediamine hydrochloride nanoisland @ graphene heterojunction material prepared in example 1. As can be seen from fig. 3, in this embodiment, two-dimensional Ni-p-phenylenediamine hydrochloride nanoislands are grown in situ on the graphene surface.
Fig. 4 is a membrane interface transmission electron microscope atomic micrograph of the heterojunction self-assembled hydrophobic nanofiltration membrane of example 2, and as can be seen from fig. 4, two-dimensional Ni-p-phenylenediamine hydrochloride nanoislands are sandwiched by two layers of graphene, forming sub-nanoscale channels.
Fig. 5 shows contact angle tests of the heterojunction self-assembled hydrophobic nanofiltration membrane of example 2 and the graphene nanofiltration membrane of the control group, in which the graphene nanofiltration membrane (GO) is prepared by suction filtration of a GO suspension onto a substrate (e.g., PES substrate) and then drying, and the specific procedure references (dr. Mengchen Zhang, yanyang Mao, guozhen Liu, prof. Gonping Liu, prof. Yiqun Fan, prof. Wanqin jin. Molecular Bridges Stabilize Graphene Oxide Membranes in Water [ J ]. Angewandte Chemie,2020,132 (4)) show that the contact angle of the two-dimensional Ni-p-phenylenediamine hydrochloride nano island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane of example 2 is 84 ° and has good hydrophobicity. As can be seen from fig. 3 to 5, the nanofiltration membrane of example 2 is internally enriched with hydrophobic pore channels of sub-nanometer scale.
Table 1 shows the water flux and ion barrier properties of nanofiltration membranes prepared in example 2. Table 2 is a water flux and ion barrier performance table of a Graphene Oxide (GO) water treatment membrane as a control.
The test methods for water flux and ion barrier properties are those described in the references (Ion sieving in graphene oxide membranes via cationic control of interlayer spacing [ J ]. Science Foundation in China,2017,25 (04): 13.).
Table 1 example 2 permeation experimental results of two-dimensional Ni-pPD nanoislands @ graphene heterojunction self-assembled nanofiltration membranes.
Table 2 permeation test results of the control group two-dimensional graphene oxide nanofiltration membrane.
From tables 1 and 2, it can be seen that the nanofiltration membrane prepared in example 2 has better water flux and ion barrier property than the control group, and can achieve both high water flux and high ion barrier property.
Example 3
The two-dimensional nano island adopted in the embodiment 3 is a Ni-hexaaminobenzene (Ni-HAB) metal organic material, and a two-dimensional Ni-hexaaminobenzene nano island@graphene heterojunction material is constructed, and the two-dimensional Ni-hexaaminobenzene (Ni-HAB) nano island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane is prepared based on the embodiment 4.
A preparation method of a two-dimensional Ni-hexaaminobenzene (Ni-HAB) nanometer island @ graphene heterojunction comprises the following specific steps:
(1) 2.2 g of nickel nitrate (NiNO 3 ) Adding into 20mL deionized water, stirring for dissolving, adding 32mL GO suspension with concentration of 5mg/mL, introducing argon while stirring, and introducing air for 1h to remove air in the solution to obtain solution A;
(2) Adding 2.2 g of Hexaminobenzene (HAB) which adopts commercial sigma medicines and has the purity of >99 percent (chemical purity) into 50ml of deionized water, stirring and dissolving, introducing argon while stirring, and introducing for 1h to remove air in the solution, so as to obtain a solution B (two-dimensional nanometer island precursor material aqueous solution);
(3) Adding the solution B into the solution A, gradually adding ammonia water with the total volume of 30ml, and carrying out oxygen radical catalytic reaction at the reaction temperature of 10 ℃ for 20 hours; after the reaction is finished, pouring the reaction solution into a suction filtration bottle for suction filtration, firstly, performing suction filtration by using deionized water, then performing suction filtration by using ethanol, finally, performing suction filtration by using deionized water, performing suction filtration for 4 hours, and washing to obtain the two-dimensional Ni-hexaaminobenzene (Ni-HAB) nano island@graphene heterojunction material.
Example 4
A preparation method of a two-dimensional Ni-hexaaminobenzene (Ni-HAB) nano island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane comprises the following specific steps:
a. weighing the two-dimensional Ni-hexaaminobenzene (Ni-HAB) nano island@graphene heterojunction material, dispersing the material into deionized water, preparing heterojunction suspension with the dispersity of 2mg/mL, and then performing ultrasonic dispersion for 1h;
b. according to the thickness of the nanofiltration membrane to be prepared, dripping the suspension on a Polystyrene (PS) substrate membrane (the PS substrate membrane is a porous substrate membrane prepared by adopting PS materials and is also a standard substrate of standard materials, and can be purchased commercially, and the specification used in the implementation is phi 50mm aperture 0.22um and membrane thickness 110 micrometers), and carrying out suction filtration for 3 hours; after the suction filtration is finished, the polyethersulfone containing suspension is placed in two glass sheets, the pressure of 20N is applied to extrude the polyethersulfone, then the polyethersulfone is dried in vacuum at the temperature of 70 ℃, the vacuum degree is 10Pa, and after the drying is finished, the glass sheets are opened at normal temperature, thus obtaining the two-dimensional Ni-hexaaminobenzene (Ni-HAB) nano island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane.
Example 5
The two-dimensional nano island adopted in the embodiment 5 is a graphite alkyne (GDY) material, and a two-dimensional graphite alkyne (GDY) nano island @ graphene heterojunction material is constructed, and the two-dimensional graphite alkyne (GDY) nano island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane is prepared based on the embodiment 6.
A preparation method of a two-dimensional graphite alkyne (GDY) nanometer island @ graphene heterojunction comprises the following specific steps:
(1) Adding 0.2 g of hexa (ethynyl) benzene (HEB) into 100ml of pyridine, stirring and dissolving, adding 5mg of GO powder, stirring (the GO powder is obtained by freeze-drying GO suspension, the GO suspension is prepared by a traditional Hummer's Method or can be purchased from a commercial product), and introducing argon while stirring for 2 hours to remove air in the solution to obtain solution A;
(2) Heating the solution A to 110 ℃, putting copper wires into the solution A, and carrying out oxygen group catalytic reaction at 110 ℃ for 20 hours; after the reaction is finished, pouring the reaction solution into a suction filtration bottle for suction filtration, firstly, performing suction filtration by using ethanol, then performing suction filtration by using N, N-Dimethylformamide (DMF), finally, performing suction filtration by using deionized water, performing total suction filtration for 6 hours, and washing to obtain the two-dimensional graphite alkyne (GDY) nano island @ graphene heterojunction material.
Example 6
A preparation method of a two-dimensional graphite alkyne (GDY) nanometer island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane specifically comprises the following steps:
a. weighing the two-dimensional graphite alkyne (GDY) nanometer island@graphene heterojunction material, dispersing the material into deionized water, preparing heterojunction suspension with a dispersity of 2mg/mL, and then performing ultrasonic dispersion for 1h;
b. according to the thickness of the nanofiltration membrane to be prepared, dripping the suspension on a Polystyrene (PS) substrate membrane (the PS substrate membrane is a porous substrate membrane prepared by adopting PS materials and is also a standard substrate of standard materials, and can be purchased commercially, and the specification used in the implementation is phi 50mm aperture 0.22um and membrane thickness 110 micrometers), and carrying out suction filtration for 4 hours; after the suction filtration is finished, the polyethersulfone containing suspension is placed in two glass sheets, the pressure of 20N is applied to extrude the polyethersulfone, then the polyethersulfone is dried in vacuum at the temperature of 70 ℃ and the vacuum degree is 10Pa, and after the drying is finished, the glass sheets are opened at normal temperature, thus obtaining the two-dimensional graphite alkyne (GDY) nanometer island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane.
The performances of the two-dimensional Ni-hexaaminobenzene (Ni-HAB) nano island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane obtained in example 4 and the two-dimensional graphite alkyne (GDY) nano island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane obtained in example 6 are equivalent to those of the two-dimensional Ni-p-phenylenediamine hydrochloride nano island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane of example 2 in terms of high water flux and high ion barrier property.
The foregoing has shown and described the basic principles and main features of the present invention and the advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (8)
1. The preparation method of the hydrophobic two-dimensional nano island @ graphene heterojunction material of the self-assembled hydrophobic nanofiltration membrane is characterized in that the two-dimensional nano island material is grown on the surface of graphene through an oxygen group catalytic reaction to prepare the hydrophobic two-dimensional nano island @ graphene heterojunction material, wherein the two-dimensional nano island structure is Ni-p-phenylenediamine hydrochloride, cu-p-phenylenediamine hydrochloride, ni-hexaaminobenzene, cu-hexaaminobenzene, graphite alkyne or Cu-hexamercaptobenzene, and the area ratio of the two-dimensional nano island material to the graphene is 10-70%;
in the prepared hydrophobic two-dimensional nano island@graphene heterojunction material, the contact angle of the two-dimensional nano island is 60-120 degrees, and the contact angle of the two-dimensional graphene is 60-90 degrees;
the hydrophobic two-dimensional nano island@graphene heterojunction material is prepared by the following steps:
(1) Adding graphene oxide suspension into a soluble metal salt solution, and introducing inert gas to remove oxygen to obtain a solution A;
(2) Dissolving a two-dimensional nanometer island precursor material into water, and introducing inert gas to remove oxygen to obtain a solution B;
(3) Adding the solution B into the solution A for oxygen group catalytic reaction at the reaction temperature of-30-150 ℃ for 0.5-96 h, carrying out suction filtration and washing to prepare a hydrophobic two-dimensional nano island@graphene heterojunction material;
the soluble metal salt solution in the step (1) is a soluble metal salt solution of nickel or a soluble metal salt solution of copper;
the two-dimensional nanometer island precursor material in the step (2) is p-phenylenediamine hydrochloride, hexaaminobenzene, graphite alkyne or hexamercaptobenzene;
the concentration of the graphene oxide suspension in the step (1) is 0.1-5 mg/mL; the concentration of the solution B in the step (2) is 0.1-1 mol/L; the inert gas used in the steps (1) and (2) is argon or nitrogen, and the inert gas is introduced for 0.1 to 24 hours;
in the step (3), the reaction temperature is 10-110 ℃ and the reaction time is 5-20 h.
2. The hydrophobic two-dimensional nano island @ graphene heterojunction material of claim 1, wherein in the step (3), the volume ratio of the solution B to the solution a is (0.1-10): 1.
3. the use of a hydrophobic two-dimensional nano-island @ graphene heterojunction material as claimed in claim 1 or 2 in the preparation of self-assembled hydrophobic nanofiltration membranes.
4. The method for preparing the two-dimensional nano island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane by using the hydrophobic two-dimensional nano island @ graphene heterojunction material as claimed in claim 1 or 2, which is characterized by comprising the following steps:
a. preparing a pumping filtrate: preparing the hydrophobic two-dimensional nano island@graphene heterojunction material into a suspension;
b. suction filtration and drying: and d, placing the suspension in the step a on a substrate film, carrying out suction filtration, and then extruding the hydrophobic two-dimensional nano island@graphene heterojunction material in the suspension onto the substrate film under external pressure, and drying to obtain the two-dimensional nano island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane.
5. The method of claim 4, wherein in step a, the concentration of the configured hydrophobic two-dimensional nano-island @ graphene heterojunction material suspension is 1-10 mg/mL.
6. The method of claim 4, wherein in step b, the substrate film material is polyethersulfone, polystyrene, mixed cellulose ester, polyvinyl chloride, polyacrylonitrile, polycarbonate, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, or porous alumina;
in the step b, the pressure applied during extrusion is 1-100N;
in the step b, the drying is carried out in a vacuum drying mode, and the drying temperature is 25-150 ℃; the drying time is 0.5-96 hours; the vacuum degree adopted for drying is 1 Pa-1 atmosphere.
7. The two-dimensional nanometer island@graphene heterojunction self-assembled hydrophobic nanofiltration membrane prepared by the method of any one of claims 4-6 is characterized in that the interior of the nanofiltration membrane is rich in sub-nanometer level hydrophobic pore channels, and the size of the hydrophobic pore channels is 0.1-1 nanometer.
8. The use of the two-dimensional nano-island @ graphene heterojunction self-assembled hydrophobic nanofiltration membrane as claimed in claim 7 in water treatment, wherein the water treatment is sea water desalination treatment, industrial wastewater treatment or municipal wastewater treatment.
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