CN116550160B - Electrochemical regulation and control method for microstructure of metal hollow fiber membrane - Google Patents
Electrochemical regulation and control method for microstructure of metal hollow fiber membrane Download PDFInfo
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- CN116550160B CN116550160B CN202310812613.4A CN202310812613A CN116550160B CN 116550160 B CN116550160 B CN 116550160B CN 202310812613 A CN202310812613 A CN 202310812613A CN 116550160 B CN116550160 B CN 116550160B
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- 239000012528 membrane Substances 0.000 title claims abstract description 132
- 239000012510 hollow fiber Substances 0.000 title claims abstract description 128
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 100
- 239000002184 metal Substances 0.000 title claims abstract description 100
- 238000000034 method Methods 0.000 title claims abstract description 43
- 238000000926 separation method Methods 0.000 claims abstract description 58
- 239000003792 electrolyte Substances 0.000 claims abstract description 25
- 230000002378 acidificating effect Effects 0.000 claims abstract description 14
- 229910000990 Ni alloy Inorganic materials 0.000 claims description 29
- 229910052739 hydrogen Inorganic materials 0.000 claims description 16
- 239000001257 hydrogen Substances 0.000 claims description 16
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 12
- 239000003822 epoxy resin Substances 0.000 claims description 8
- 229920000647 polyepoxide Polymers 0.000 claims description 8
- -1 hydrogen ions Chemical class 0.000 claims description 7
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 6
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 3
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 3
- 229910017604 nitric acid Inorganic materials 0.000 claims description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 2
- 229910052802 copper Inorganic materials 0.000 claims description 2
- 239000010949 copper Substances 0.000 claims description 2
- 229910052709 silver Inorganic materials 0.000 claims description 2
- 239000004332 silver Substances 0.000 claims description 2
- 239000010935 stainless steel Substances 0.000 claims description 2
- 229910001220 stainless steel Inorganic materials 0.000 claims description 2
- 238000012546 transfer Methods 0.000 abstract description 4
- 239000002253 acid Substances 0.000 description 15
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
- 238000005260 corrosion Methods 0.000 description 6
- 230000007797 corrosion Effects 0.000 description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 6
- 238000007789 sealing Methods 0.000 description 6
- 238000005530 etching Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- GTKRFUAGOKINCA-UHFFFAOYSA-M chlorosilver;silver Chemical compound [Ag].[Ag]Cl GTKRFUAGOKINCA-UHFFFAOYSA-M 0.000 description 3
- 150000002431 hydrogen Chemical class 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 238000010306 acid treatment Methods 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 238000010926 purge Methods 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 229910052580 B4C Inorganic materials 0.000 description 1
- 229910000599 Cr alloy Inorganic materials 0.000 description 1
- 229910003271 Ni-Fe Inorganic materials 0.000 description 1
- 229910018559 Ni—Nb Inorganic materials 0.000 description 1
- 229910000756 V alloy Inorganic materials 0.000 description 1
- INAHAJYZKVIDIZ-UHFFFAOYSA-N boron carbide Chemical compound B12B3B4C32B41 INAHAJYZKVIDIZ-UHFFFAOYSA-N 0.000 description 1
- 229940075397 calomel Drugs 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical compound Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000006056 electrooxidation reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 229910021397 glassy carbon Inorganic materials 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0081—After-treatment of organic or inorganic membranes
- B01D67/0093—Chemical modification
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/08—Hollow fibre membranes
Abstract
The invention relates to an electrochemical regulation and control method of a metal hollow fiber membrane microstructure and a metal hollow fiber membrane. The metal hollow fiber membrane comprises a porous support layer, a first dense separation layer positioned on the inner side of the porous support layer and a second dense separation layer positioned on the outer side of the porous support layer, and one end of the metal hollow fiber membrane is sealed, and the method comprises the following electrochemical treatment steps: and connecting an unsealed end of the metal hollow fiber membrane with an anode to serve as a working electrode by using a three-electrode system, and performing electrochemical treatment on the metal hollow fiber membrane by using an acidic electrolyte as the electrolyte to remove the second dense separation layer of the metal hollow fiber membrane. The electrochemical regulation and control method of the metal hollow fiber membrane microstructure can accurately remove the second compact separation layer positioned on the outer side of the porous support layer, and further reduce separation mass transfer resistance on the basis of maintaining the original separation performance.
Description
Technical Field
The invention belongs to the field of gas separation, and particularly relates to electrochemical regulation and control of a metal hollow fiber membrane microstructure.
Background
The metal hollow fiber membrane can be used for preparing porous electrodes, porous carriers, separation membranes and the like. Compared with the traditional metal film, the metal hollow fiber film has simple preparation process, large filling area and greatly reduced equipment volume, and is an advanced metal film configuration.
CN105195030a discloses a nickel alloy hollow fiber membrane, which is prepared by a phase inversion and sintering technology, and as shown in fig. 1, the nickel alloy hollow fiber membrane is composed of a porous supporting layer, a compact separating layer located inside the porous supporting layer, and a compact separating layer located outside the porous supporting layer. However, in this structure, there is not little mass transfer resistance due to the dense separation layer on both the inside and outside of the porous support layer.
In the prior art, a method for dissolving a ceramic membrane compact separation layer through acid corrosion is reported, but the original compact layer is only about 5-50 mu m in thickness, so that the acid corrosion process is not easy to control. In addition, the porous support layer and the inner dense separation layer are extremely susceptible to complete corrosion penetration, resulting in loss of separation performance.
Thus, there is a need for a conditioning method that enables precise removal of dense separation layers of metal hollow fiber membranes, particularly dense separation layers located outside of porous support layers, while the porous support layers and the dense separation layers inside remain structurally intact.
Disclosure of Invention
In order to solve the problems in the prior art, the inventors have conducted intensive studies and found that at least one technical problem in the prior art can be solved by the electrochemical regulation method for the microstructure of the metal hollow fiber membrane.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
in one aspect, the invention provides a method for electrochemically modulating the microstructure of a metal hollow fiber membrane, the metal hollow fiber membrane comprises a porous support layer, a first dense separation layer positioned on the inner side of the porous support layer and a second dense separation layer positioned on the outer side of the porous support layer, and one end of the metal hollow fiber membrane is sealed,
the method comprises the following electrochemical treatment steps: and connecting an unsealed end of the metal hollow fiber membrane with an anode to serve as a working electrode by using a three-electrode system, and performing electrochemical treatment on the metal hollow fiber membrane by using an acidic electrolyte as the electrolyte to remove the second dense separation layer of the metal hollow fiber membrane.
In the electrochemical control method of the metal hollow fiber membrane microstructure, it is preferable that the acidic electrolyte used in the electrochemical treatment step is one or more selected from sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid, and the concentration of hydrogen ions in the acidic electrolyte is 0.05 to 1mol/L.
In the electrochemical control method of the microstructure of the metal hollow fiber membrane, the metal of the metal hollow fiber membrane used in the sealing treatment step is preferably nickel alloy, stainless steel, copper, or silver. Examples of the nickel alloy include Ni-Fe alloy, ni-Cr alloy, ni-V alloy, and Ni-Nb.
In the electrochemical control method for a metal hollow fiber membrane microstructure, it is preferable that the thickness of the first dense separation layer is 5 to 50 μm, the thickness of the second dense separation layer is 5 to 50 μm, and the thickness of the porous support layer is 50 to 200 μm.
In the electrochemical control method of the microstructure of the metal hollow fiber membrane, one end of the metal hollow fiber membrane is preferably sealed with an epoxy resin.
In the electrochemical regulation method of the metal hollow fiber membrane microstructure, preferably, a constant current method is adopted in the electrochemical treatment step, the current is 50-500 mA, and the electrochemical treatment time is 1-30 min.
In the electrochemical regulation method of the metal hollow fiber membrane microstructure, preferably, a constant voltage method is adopted in the electrochemical treatment step, the voltage is 1-10 v, and the electrochemical treatment time is 1-30 min.
In another aspect, the present invention also provides a metal hollow fiber membrane from which the second dense separation layer is removed by the electrochemical modulation method of the microstructure of the metal hollow fiber membrane described in any one of the foregoing.
By adopting the electrochemical regulation method of the metal hollow fiber membrane microstructure, the corrosion progress can be accurately controlled by controlling the current and/or the voltage in the electrochemical treatment step, and the acid electrolyte used as the electrolyte is required to be of low concentration. Therefore, the electrochemical regulation method of the metal hollow fiber membrane microstructure can accurately remove the second dense separation layer positioned on the outer side of the porous support layer under the condition of not damaging the porous support layer and the dense separation layer positioned on the inner side of the porous support layer, and further reduce separation mass transfer resistance on the basis of maintaining the original separation performance of the metal hollow fiber membrane.
Drawings
Fig. 1 shows a schematic diagram of a three-electrode system used in the electrochemical regulation method of the metal hollow fiber membrane microstructure of one embodiment.
Fig. 2 shows a schematic cross-sectional view of a metal hollow fiber membrane used in one embodiment prior to electrochemical treatment.
Fig. 3 is a schematic cross-sectional view of the metal hollow fiber membrane shown in fig. 2 after the electrochemical control method of the metal hollow fiber membrane microstructure according to one embodiment is performed.
Fig. 4 (a) and 4 (c) show an electron microscopic view of a cross section of the metal hollow fiber membrane used in example 1 before electrochemical treatment, and fig. 4 (b) and 4 (d) show an electron microscopic view of a cross section of the metal hollow fiber membrane used in example 1 after electrochemical treatment, respectively.
In fig. 5, fig. 5 (a) and 5 (c) show a cross-sectional electron microscopic image and an outer surface electron microscopic image of the metal hollow fiber membrane of comparative example 1 after acid etching, respectively, and fig. 5 (b) and 5 (d) show a cross-sectional electron microscopic image and an outer surface electron microscopic image of the metal hollow fiber membrane of comparative example 2 after high-concentration acid etching, respectively.
Fig. 6 shows graphs showing the changes in hydrogen separation performance of the untreated nickel alloy hollow fiber membrane (HF-01), the electrochemically treated nickel alloy hollow fiber membrane (HF-02) of example 1, and the acid-etched nickel alloy hollow fiber membrane (HF-03) of comparative example 1.
Reference numerals:
1-a second dense separating layer; 2-a porous support layer; 3-a first dense separation layer; 4-a hollow hole; 5-working electrode; 6-a reference electrode; 7-a pair of electrodes; 8-acid electrolyte.
Detailed Description
The present invention will be further described in detail with reference to examples, but the scope of the present invention is not limited to the examples. It is to be understood by persons of ordinary skill in the art that the following detailed description is illustrative and not restrictive, and should not be taken as limiting the scope of the present disclosure.
In the specification, unless specified otherwise, the percentages refer to mass percentages and the temperature is in degrees centigrade (DEG C).
The metal hollow fiber membrane used in the invention has the following structure: comprises a porous support layer, a first dense separation layer positioned on the inner side of the porous support layer, and a second dense separation layer positioned on the outer side of the porous support layer, and one end of the metal hollow fiber membrane is sealed by epoxy resin.
In some embodiments, the metal hollow fiber membrane is composed of only a porous support layer and a first dense separation layer located inside the porous support layer and a second dense separation layer located outside the porous support layer.
The length, inner and outer diameters, wall thickness, and other dimensions of the metal hollow fiber membrane are not particularly limited. In some embodiments, the metal hollow fiber membranes may have an inner diameter of, for example, 500 to 2000 microns. In some embodiments, the metal hollow fiber membrane may have a wall thickness of, for example, 50 to 200 microns.
One end of the metal hollow fiber membrane is sealed. The material used for the sealing is not particularly limited, and may be a material used for a sealing treatment of a usual metal hollow fiber membrane, for example, epoxy resin, polytetrafluoroethylene, or the like, and is preferably sealed with an epoxy resin. The method of sealing is not particularly limited. The sealing may be performed by a method used in a usual sealing treatment of a metal hollow fiber membrane.
The three-electrode system used in electrochemical processing contains a working electrode, a reference electrode, and a counter electrode. The three-electrode system comprises two loops, wherein one loop consists of a working electrode and a reference electrode, and the other loop consists of a working electrode and a counter electrode. The current is measured by a loop formed by the working electrode and the counter electrode, and the voltage is measured by the reference electrode, so that the change of the current and the voltage can be monitored simultaneously.
In the electrochemical treatment step, one end of the metal hollow fiber membrane which is not sealed is connected to an anode of a three-electrode system to serve as a working electrode, an acidic electrolyte is used as an electrolyte, the metal hollow fiber membrane is subjected to electrochemical oxidation, and the second dense separation layer in the metal hollow fiber membrane is removed.
The counter electrode used in the three-electrode system is not particularly limited, and for example, a platinum wire electrode, a platinum sheet electrode, a gold electrode, a carbon paste electrode, a boron carbide electrode, or the like can be used. A platinum wire electrode or a platinum sheet electrode is preferably used as the counter electrode.
The reference electrode used in the three-electrode system is not particularly limited, and for example, a calomel electrode, a glassy carbon electrode, or a silver-silver chloride electrode can be used as the reference electrode. A silver-silver chloride electrode is preferably used as the reference electrode.
The acidic electrolyte may be, for example, one or more selected from sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid, and is not particularly limited.
The hydrogen ion concentration of the acidic electrolyte is preferably 1mol/L or less, more preferably 0.5mol/L or less, whereby strong corrosion of the metal hollow fiber membrane by the acidic electrolyte itself due to too high a hydrogen ion concentration can be avoided. The concentration of hydrogen ions in the acidic electrolyte is preferably 0.05mol/L or more, more preferably 0.1mol/L or more, whereby the efficiency of the electrochemical treatment can be improved.
In some embodiments, the electrochemical treatment step may be performed by a constant current method, the current range may be, for example, 50-500 ma, the electrochemical treatment time may be different according to the material of the metal hollow fiber membrane to be treated, the thickness of the second dense separation layer, the concentration of the acid electrolyte, the set current, and the like, and may be appropriately adjusted as required, so long as the second dense separation layer of the metal hollow fiber membrane can be precisely removed, and the structural integrity of the porous support layer and the first dense separation layer of the metal hollow fiber membrane is maintained. The time of the electrochemical treatment may be, for example, in the range of 1 to 30 minutes. When the operation time is less than 1min, it is difficult to precisely remove the second dense separation layer of the metal hollow fiber membrane by the aforementioned electrochemical treatment. When the operation time exceeds 30 minutes, the first dense separation layer is easily eroded, resulting in the loss of separation performance of the membrane. In addition, it is uneconomical in terms of work efficiency.
In some embodiments, the electrochemical treatment may be performed by a constant voltage method, and the voltage may vary, for example, from 1 v to 10 v. The time of the electrochemical treatment may be, for example, in the range of 1 to 30 minutes. When the operation time is less than 1min, it is difficult to precisely remove the second dense separation layer of the metal hollow fiber membrane by the aforementioned electrochemical treatment. When the operation time exceeds 30 minutes, the first dense separation layer is easily eroded, resulting in a loss of separation performance of the membrane, and it is uneconomical from the viewpoint of working efficiency.
In the electrochemical treatment of the metal hollow fiber membrane, the following electrochemical reaction occurs:
on the anode side, the metal on the surface of the metal hollow fiber membrane is oxidized, and on the cathode side, hydrogen ions in the electrolyte are reduced to generate hydrogen gas.
Specifically, a nickel hollow fiber membrane will be described as an example. When a nickel hollow fiber membrane is used as the metal hollow fiber membrane, the following reactions occur on the anode side and the cathode side, respectively:
anode side: ni-2 e- & gtNi 2+
Cathode side: h + +2e→H 2
In the case where the metal hollow fiber membrane is a metal or an alloy other than nickel, the metal similar to the above is oxidized at the anode to generate metal ions, and the hydrogen ions are reduced to hydrogen gas at the cathode side.
Fig. 1 shows a schematic diagram of a three-electrode system used in the electrochemical regulation method of the metal hollow fiber membrane microstructure of one embodiment. The three-electrode system shown in fig. 1 has: a working electrode 5, a reference electrode 6, a counter electrode 7, and an acidic electrolyte 8 as an electrolyte. In the electrochemical treatment, as the working electrode 5, the unsealed end of the metal hollow fiber membrane is connected to the anode, and the end of the metal hollow fiber membrane immersed in the acid electrolyte 8 is the sealed end.
Fig. 2 shows a schematic cross-sectional view of a metal hollow fiber membrane used in one embodiment prior to electrochemical treatment. As shown in fig. 2, the porous support layer 2, the first dense separation layer 3 located inside the porous support layer 2, and the second dense separation layer 1 located outside the porous support layer 1 constitute a metal hollow fiber membrane. The hollow bore 4 of the metal hollow fiber membrane is surrounded by the first dense separation layer 3.
Fig. 3 is a schematic cross-sectional view of the metal hollow fiber membrane shown in fig. 1 after the electrochemical control method of the microstructure of the metal hollow fiber membrane is performed. In comparison with the cross-sectional view shown in fig. 2 before the electrochemical regulation method is performed, the aforementioned second dense separation layer 1 is removed by electrochemical treatment.
Examples
Example 1
An electrochemical workstation (CHI 760E, shanghai Chen Hua instruments Co., ltd.) of a three-electrode system is adopted to prepare a hydrochloric acid solution with the concentration of 0.2mol/L as an acidic electrolyte, a nickel alloy (60 percent Ni-40 percent Fe), a nickel alloy hollow fiber membrane with the length of 10cm, the outer diameter OD=1.2 mm and the inner diameter ID=1.0 mm is adopted, one end of the nickel alloy hollow fiber membrane is sealed by epoxy resin, the other end is connected with an anode of the electrochemical workstation, the anode is used as a working electrode, a carbon rod is used as a counter electrode, a silver-silver chloride electrode is used as a reference electrode, a constant voltage method is adopted, the current is set to be 2V, and the operation time is 10min, so that electrochemical treatment is carried out. The cross section and the surface of the nickel alloy hollow fiber membrane before and after the electrochemical treatment were scanned by a scanning electron microscope (PHENOMSCIENTIFIC Phenom ProX), and fig. 4 was obtained. Specifically, fig. 4 (a) is an electron microscopic view of a cross section of a metal of the nickel alloy hollow fiber membrane before electrochemical treatment, and fig. 4 (c) is an electron microscopic view of a surface of the nickel alloy hollow fiber membrane before electrochemical treatment. Fig. 4 (b) is an electron microscopic view of a cross section of the nickel alloy hollow fiber membrane after electrochemical treatment, and fig. 4 (d) is an electron microscopic view of a surface of the nickel alloy hollow fiber membrane after electrochemical treatment. As can be seen from a comparison of fig. 4 (a) and fig. 4 (b), the dense separating layer of the nickel alloy hollow fiber membrane located outside the porous supporting layer was precisely removed after the electrochemical treatment, and the integrity of the porous supporting layer of the nickel alloy hollow fiber membrane and the dense separating layer located inside thereof was maintained.
Comparative example 1
The same nickel alloy hollow fiber membrane as in example 1 was used, both ends thereof were sealed with an epoxy resin, and then immersed in a hydrochloric acid solution of 0.2mol/L concentration for 10 minutes, and taken out, and the cross section and the surface of the nickel alloy hollow fiber membrane after the acid treatment were scanned by a scanning electron microscope (PHENOMSCIENTIFIC Phenom ProX), and a scanning electron microscope photograph obtained was shown in fig. 5. Fig. 5 (a) and 5 (c) are a cross-sectional photograph and a surface photograph of the nickel alloy hollow fiber membrane after immersion, respectively.
Comparative example 2
The same nickel alloy hollow fiber membrane as in example 1 was used, both ends thereof were sealed with an epoxy resin, and then immersed in a hydrochloric acid solution of 5mol/L concentration for 10 minutes, and taken out, and the cross section and the surface of the nickel alloy hollow fiber membrane after the acid treatment were scanned by a scanning electron microscope (PHENOMSCIENTIFIC Phenom ProX), and a scanning electron microscope photograph obtained was shown in FIG. 5. Fig. 5 (b) and 5 (d) are a cross-sectional photograph and a surface photograph of the nickel alloy hollow fiber membrane after immersion, respectively.
Hydrogen permeation performance measurement: the following air permeability was measured for the nickel alloy hollow fiber membrane (HF-01) before electrochemical treatment used in example 1, the nickel alloy hollow fiber membrane (HF-02) after electrochemical treatment in example 1, and the nickel alloy hollow fiber membrane (HF-03) after acid etching in comparative example 1, respectively: introducing H containing 50% hydrogen outside the hollow fiber membrane 2 He mixture gas with N 2 As a purge gas, H in the purge gas was measured by gas chromatography 2 The hydrogen permeation at various temperatures was calculated and the results are shown in FIG. 6.
As can be seen from FIG. 6, the hydrogen permeation rate of the hollow fiber membrane (HF-02) after the electrochemical treatment of example 1 was about 2 times that of the hollow fiber membrane (HF-01) before the treatment, and the hydrogen permeation rate of the hollow fiber membrane (HF-03) after the direct etching with acid of comparative example 1 was hardly changed. The hollow fiber membrane (HF-04) subjected to the high concentration acid corrosion of comparative example 2 lost the hydrogen separation performance due to the generation of serious leakage, and thus, the corresponding curve thereof was not shown in fig. 6.
As can be seen from a comparison of fig. 5 and 4 and fig. 6, in the case of comparative example 1, after the direct acid soaking treatment with the same acid concentration and the same treatment time as in example 1, the second dense separation layer of the nickel alloy hollow fiber membrane was not removed, so that the hydrogen permeation amount of the hollow fiber membrane HF-03 was unchanged from that of the untreated hollow fiber membrane HF-01, whereas in the case of comparative example 2, when the direct soaking hollow fiber membrane was corroded with the acid of high concentration, the metal grain boundaries on the outer surface of the nickel alloy hollow fiber membrane were corroded first, and in the case where the second dense separation layer was not completely removed, the acid solution had entered the inside of the membrane body and corroded it to the first dense separation layer, and therefore, in the hydrogen permeation performance measurement, the hydrogen permeation performance of the hollow fiber membrane HF-04 could not be measured, thereby also indicating that the hollow fiber membrane HF-04 had lost the hydrogen separation function, and serious leakage was generated.
By the above embodiment, the electrochemical regulation method of the microstructure of the metal hollow fiber membrane can accurately remove the second dense separation layer positioned outside the porous support layer without damaging the porous support layer and the dense separation layer positioned inside the porous support layer, and further reduce the separation mass transfer resistance on the basis of maintaining the original separation performance of the metal hollow fiber membrane.
It should be apparent that the foregoing examples of the present disclosure are merely illustrative of the present disclosure and not limiting of the embodiments of the present disclosure, and that various other changes and modifications may be made by one of ordinary skill in the art based on the foregoing description, and it is not intended to be exhaustive of all embodiments, and all obvious changes and modifications that come within the scope of the present disclosure are intended to be embraced by the technical solution of the present disclosure.
Claims (8)
1. An electrochemical regulation method for a microstructure of a metal hollow fiber membrane is characterized in that the metal hollow fiber membrane comprises a porous supporting layer, a first dense separating layer positioned at the inner side of the porous supporting layer and a second dense separating layer positioned at the outer side of the porous supporting layer, one end of the metal hollow fiber membrane is sealed,
the method comprises the following electrochemical treatment steps: and connecting an unsealed end of the metal hollow fiber membrane with an anode to serve as a working electrode by using a three-electrode system, and performing electrochemical treatment on the metal hollow fiber membrane by using an acidic electrolyte as the electrolyte to remove the second dense separation layer of the metal hollow fiber membrane.
2. The electrochemical control method of a metal hollow fiber membrane microstructure according to claim 1, wherein the acidic electrolyte used in the electrochemical treatment step is one or more selected from sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid, and the concentration of hydrogen ions in the acidic electrolyte is 0.05-1 mol/L.
3. The method for electrochemical regulation of a metal hollow fiber membrane microstructure according to claim 1, wherein the metal in the metal hollow fiber membrane is nickel alloy, stainless steel, copper, or silver.
4. The electrochemical control method of a metal hollow fiber membrane microstructure according to claim 1, wherein the thickness of the first dense separation layer is 5-50 μm, the thickness of the second dense separation layer is 5-50 μm, and the thickness of the porous support layer is 50-200 μm.
5. The electrochemical regulation method of a metal hollow fiber membrane microstructure according to claim 1, wherein one end of the metal hollow fiber membrane is sealed with an epoxy resin.
6. The electrochemical regulation method of the metal hollow fiber membrane microstructure according to claim 1, wherein a constant current method is adopted in the electrochemical treatment step, the current is 50-500 mA, and the electrochemical treatment time is 1-30 min.
7. The electrochemical regulation method of the metal hollow fiber membrane microstructure according to claim 1, wherein a constant voltage method is adopted in the electrochemical treatment step, the voltage is 1-10 v, and the electrochemical treatment time is 1-30 min.
8. A metal hollow fiber membrane from which the second dense separation layer of the metal hollow fiber membrane is removed by electrochemical modulation of the metal hollow fiber membrane microstructure of any one of claims 1 to 7.
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| WO2004006377A1 (en) * | 2002-07-02 | 2004-01-15 | Microcell Corporation | Microcell electrochemical devices and assemblies with corrosion-resistant current collectors, and method of making the same |
| CN110498501A (en) * | 2019-08-30 | 2019-11-26 | 镇江庄湖材料科技有限公司 | A kind of electrochemical membrane bioreactor of antimicrobial fouling membrane |
| CN113546526A (en) * | 2021-08-30 | 2021-10-26 | 大连海事大学 | Asymmetric hollow fiber titanium-based membrane and preparation method thereof |
| KR20210156133A (en) * | 2020-06-17 | 2021-12-24 | 한국원자력연구원 | Filter and Method for Manufacturing Filter |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004006377A1 (en) * | 2002-07-02 | 2004-01-15 | Microcell Corporation | Microcell electrochemical devices and assemblies with corrosion-resistant current collectors, and method of making the same |
| CN110498501A (en) * | 2019-08-30 | 2019-11-26 | 镇江庄湖材料科技有限公司 | A kind of electrochemical membrane bioreactor of antimicrobial fouling membrane |
| KR20210156133A (en) * | 2020-06-17 | 2021-12-24 | 한국원자력연구원 | Filter and Method for Manufacturing Filter |
| CN113546526A (en) * | 2021-08-30 | 2021-10-26 | 大连海事大学 | Asymmetric hollow fiber titanium-based membrane and preparation method thereof |
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