CN118518738B - Device and method for measuring single ion mass transfer resistance of polyamide membrane - Google Patents
Device and method for measuring single ion mass transfer resistance of polyamide membrane Download PDFInfo
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- CN118518738B CN118518738B CN202410985012.8A CN202410985012A CN118518738B CN 118518738 B CN118518738 B CN 118518738B CN 202410985012 A CN202410985012 A CN 202410985012A CN 118518738 B CN118518738 B CN 118518738B
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- 239000012528 membrane Substances 0.000 title claims abstract description 143
- 239000004952 Polyamide Substances 0.000 title claims abstract description 116
- 229920002647 polyamide Polymers 0.000 title claims abstract description 116
- 238000012546 transfer Methods 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 32
- 210000005056 cell body Anatomy 0.000 claims abstract description 80
- 239000003014 ion exchange membrane Substances 0.000 claims abstract description 29
- 210000004027 cell Anatomy 0.000 claims abstract description 15
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 48
- 150000002500 ions Chemical class 0.000 claims description 42
- 229910052697 platinum Inorganic materials 0.000 claims description 24
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 18
- 229910021607 Silver chloride Inorganic materials 0.000 claims description 17
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 claims description 17
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 16
- 239000002131 composite material Substances 0.000 claims description 16
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 9
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 9
- 229910052719 titanium Inorganic materials 0.000 claims description 9
- 239000010936 titanium Substances 0.000 claims description 9
- 150000001450 anions Chemical class 0.000 claims description 8
- 150000001768 cations Chemical class 0.000 claims description 8
- 238000002791 soaking Methods 0.000 claims description 7
- 229910021642 ultra pure water Inorganic materials 0.000 claims description 7
- 239000012498 ultrapure water Substances 0.000 claims description 7
- 229910020366 ClO 4 Inorganic materials 0.000 claims description 3
- 238000001228 spectrum Methods 0.000 claims description 2
- 238000012360 testing method Methods 0.000 abstract description 18
- 238000005516 engineering process Methods 0.000 abstract description 4
- 238000001514 detection method Methods 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 41
- 102000015863 Nuclear Factor 90 Proteins Human genes 0.000 description 24
- 108010010424 Nuclear Factor 90 Proteins Proteins 0.000 description 24
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 18
- 238000005341 cation exchange Methods 0.000 description 14
- 239000003011 anion exchange membrane Substances 0.000 description 13
- 241000219053 Rumex Species 0.000 description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 9
- 235000011164 potassium chloride Nutrition 0.000 description 9
- 239000001103 potassium chloride Substances 0.000 description 9
- 239000004745 nonwoven fabric Substances 0.000 description 8
- 229910001415 sodium ion Inorganic materials 0.000 description 8
- 229910001414 potassium ion Inorganic materials 0.000 description 7
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- 230000008569 process Effects 0.000 description 5
- GLUUGHFHXGJENI-UHFFFAOYSA-N Piperazine Chemical compound C1CNCCN1 GLUUGHFHXGJENI-UHFFFAOYSA-N 0.000 description 4
- 230000005684 electric field Effects 0.000 description 4
- 238000004502 linear sweep voltammetry Methods 0.000 description 4
- 239000011148 porous material Substances 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 238000001075 voltammogram Methods 0.000 description 4
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 description 3
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 3
- UWCPYKQBIPYOLX-UHFFFAOYSA-N benzene-1,3,5-tricarbonyl chloride Chemical compound ClC(=O)C1=CC(C(Cl)=O)=CC(C(Cl)=O)=C1 UWCPYKQBIPYOLX-UHFFFAOYSA-N 0.000 description 3
- 238000012512 characterization method Methods 0.000 description 3
- 229940018564 m-phenylenediamine Drugs 0.000 description 3
- 238000001728 nano-filtration Methods 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 238000012695 Interfacial polymerization Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 239000010408 film Substances 0.000 description 2
- 239000013505 freshwater Substances 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000001223 reverse osmosis Methods 0.000 description 2
- -1 salt ions Chemical class 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- NPYPAHLBTDXSSS-UHFFFAOYSA-N Potassium ion Chemical compound [K+] NPYPAHLBTDXSSS-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000000157 electrochemical-induced impedance spectroscopy Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 229920002492 poly(sulfone) Polymers 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000003380 quartz crystal microbalance Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000005001 rutherford backscattering spectroscopy Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 238000010408 sweeping Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
- G01N27/333—Ion-selective electrodes or membranes
- G01N27/3335—Ion-selective electrodes or membranes the membrane containing at least one organic component
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
- B01D65/10—Testing of membranes or membrane apparatus; Detecting or repairing leaks
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/404—Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid, e.g. Clark-type oxygen sensors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/416—Systems
- G01N27/48—Systems using polarography, i.e. measuring changes in current under a slowly-varying voltage
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Electrochemistry (AREA)
- Molecular Biology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
The invention provides a device and a method for measuring single ion mass transfer resistance of a polyamide membrane. The device comprises an electrochemical workstation and a measuring cell, wherein a first signal end of the electrochemical workstation is connected with a working electrode and a recording electrode, a second signal end of the electrochemical workstation is connected with a counter electrode and a reference electrode, the measuring cell comprises a first electrolytic cell body, a second electrolytic cell body and a gasket arranged between the first electrolytic cell body and the second electrolytic cell body, a polyamide membrane and an ion exchange membrane are arranged on the gasket, the polyamide membrane is positioned on one side close to the first electrolytic cell body, the ion exchange membrane is positioned on the other side close to the second electrolytic cell body, the working electrode and the recording electrode extend into a first cavity of the first electrolytic cell body, and the counter electrode and the reference electrode extend into a second cavity of the second electrolytic cell body. The device adopts an electrochemical technology based on a four-electrode system to test the separated polyamide membrane, is simple and effective in operation and has good detection stability.
Description
Technical Field
The invention relates to the technical field of membranes, in particular to a device and a method for measuring single ion mass transfer resistance of a polyamide membrane.
Background
Membrane separation technology, particularly the use of Reverse Osmosis (RO) and Nanofiltration (NF) membranes, has become one of the important means to address the challenges of fresh water shortage worldwide. The development of these membranes, particularly thin film composite polyamide (TFC-PA) membranes, enables the efficient production of fresh water from wastewater and brine. This is critical to meeting the ever-increasing industrial, agricultural and domestic water demands, as these membranes are capable of removing a variety of dissolved impurities, including salt ions and other small molecules. Typically, commercial reverse osmosis membranes are prepared by interfacial polymerization of m-phenylenediamine (MPD) with trimesoyl chloride (TMC), while nanofiltration membranes are typically prepared by interfacial polymerization of m-phenylenediamine or piperazine (PIP) with trimesoyl chloride. These composite membranes typically consist of a top polyamide active layer (20-200 nm), an intermediate polysulfone support (20-50 μm) and a polyester backing (50-150 μm). In this structure, the polyamide active layer acts as the primary barrier to water and solute transport.
Detailed investigation of the ion mass transfer process is critical in order to optimize the performance of the polyamide membrane. Research on ion mass transfer processes typically requires the aid of advanced characterization techniques such as quartz crystal microbalances, electrochemical impedance spectroscopy, and rutherford backscattering spectroscopy. These techniques have made significant progress in studying microscopic mass transfer in the TFC-PA layer. However, it is difficult to measure the transport properties of individual ions in current research, and the presence of ion pairs may affect the behavior of individual ions, and the intra-pore diffusion of ions is often neglected. Thus, the mechanism of salt ion passage through the membrane pores remains a controversial issue.
Disclosure of Invention
In order to solve the characterization requirement of the single ion mass transfer process in the polyamide membrane in the prior art and the defects in the prior art. The invention provides a device and a method for measuring single ion mass transfer resistance of a polyamide membrane. The method has the characteristics of high sensitivity, wide applicability and simple operation, and can realize quantitative characterization of the mass transfer resistance of the single ions in the membrane. The method provides a brand new strategy and means for deeply understanding mass transfer behavior of single ions in the polyamide membrane.
A first object of the present invention is to provide an apparatus for determining the mass transfer resistance of a polyamide membrane single ion comprising:
The electrochemical working station comprises an electrochemical working station, a working electrode and a recording electrode, wherein a first signal end of the electrochemical working station is connected with the working electrode and the recording electrode, and a second signal end of the electrochemical working station is connected with a counter electrode and a reference electrode;
the measuring cell comprises a first electrolytic cell body, a second electrolytic cell body and a gasket arranged between the first electrolytic cell body and the second electrolytic cell body, wherein a polyamide membrane and an ion exchange membrane are arranged on the gasket, the polyamide membrane is positioned at one side close to the first electrolytic cell body, and the ion exchange membrane is positioned at the other side close to the second electrolytic cell body;
the first electrolytic cell body is provided with a first cavity for containing a solution to be detected, and the working electrode and the recording electrode extend into the first cavity;
the second electrolytic cell body is provided with a second cavity, the second cavity is used for containing the solution to be detected, and the counter electrode and the reference electrode extend into the second cavity.
In some embodiments of the invention, the end of the working electrode, the end of the counter electrode are formed as sheet platinum electrodes or sheet titanium electrodes;
the reference electrode and the recording electrode are Ag/AgCl electrodes;
the effective surface area of the polyamide membrane is smaller than the surface area of the flaky platinum electrode or the flaky titanium electrode;
the effective surface area of the polyamide membrane is 1-4 cm 2.
In some embodiments of the invention, the recording electrode is located on a side proximal to the polyamide membrane and the reference electrode is located on a side distal to the ion exchange membrane;
the top of the first electrolytic cell body and the second electrolytic cell body are respectively provided with a cover plate, a first through hole and a second through hole are formed in the cover plate, threaded sleeves are arranged in the first through hole and the second through hole, one threaded sleeve is used for installing the working electrode and/or the counter electrode, a Rugold capillary is arranged in the other threaded sleeve, and the Rugold capillary is internally provided with the reference electrode and/or the recording electrode.
In some embodiments of the invention, the rujin capillary is an L-shaped sand core salt bridge or an L-shaped rujin capillary;
the distance between the elbow outlet of the Rumex capillary tube and the surface of the polyamide membrane is 1-2 mm.
In some embodiments of the invention, further comprising:
The fixing rods comprise four fixing rods, and the four fixing rods penetrate through the gaskets to connect the first electrolytic cell body and the second electrolytic cell body.
A second object of the present invention is to provide a method for determining mass transfer resistance of polyamide membrane single ions using said apparatus, comprising the steps of:
S1, providing the device of any one of the above, attaching a polyamide membrane to an ion exchange membrane of the device, and injecting a solution to be tested into a first electrolytic cell body and a second electrolytic cell body of the device;
s2, starting an electrochemical workstation of the device, measuring a current-potential difference map of a single ion transmembrane, and calculating a positive/negative ion mass transfer resistance value through fitting a slope.
In some embodiments of the present invention, before using the ion exchange membrane, the ion exchange membrane is soaked in the solution to be tested for 12-72 hours;
the polyamide membrane is a composite polyamide membrane, and before the composite polyamide membrane is used, the composite polyamide membrane is soaked in an alcohol solution for 30-120 min or
Immersing the composite polyamide membrane in ultrapure water for 12-72 hours;
the alcohol solution is one or more of ethanol, methanol and isopropanol, and the volume fraction of the alcohol solution is 10% -40%.
In some embodiments of the present invention, the concentration of the solution to be measured is 0.01 mM-1000 mM;
The cations in the solution to be detected are one or more of Li+、Na+、K+、Rb+、Cs+、NH4 +、Ca2+、Mg2+、Ba2+;
the anions in the solution to be detected are one or more of Cl -、SO4 2-、NO3 -、PO4 3-、CO3 2- and ClO 4 -.
In some embodiments of the invention, the electrochemical workstation has an operating voltage of-50 mV to 50mV and a scan rate of 0.1mV/s to 100mV/s.
In some embodiments of the invention, the working current of the electrochemical workstation is-0.1 mA/cm 2~1mA/cm2, and the application time is 20-60 s.
Compared with the prior art, the technical scheme of the invention has the following advantages:
The invention adopts an electrochemical technology based on a four-electrode system to test the polyamide membrane after separation. The positive ions and the negative ions are separated by taking the electric field as a driving force, so that the positive ions and the negative ions pass through the compact sub-nano-pore polyamide membrane and the corresponding ion exchange membrane, and the quantitative and accurate test of the mass transfer resistance of the single ions is realized. The adopted linear fitting data processing process is simple and effective, and has good detection stability. The method is helpful for deeply understanding the mass transfer difference of single ions in the polyamide membrane, and provides a brand new strategy and method for clarifying and regulating the ion mass transfer process in the polyamide membrane. The research is hopeful to deepen the understanding of ion transfer in the membrane separation process, thereby further improving the efficiency and feasibility of the membrane separation technology.
Drawings
In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings, in which,
FIG. 1 is a schematic diagram of a structure for measuring mass transfer resistance of a polyamide membrane single ion in an embodiment of the invention;
FIG. 2 is a linear voltammogram of a polyamide membrane measured for resistance to mass transfer of potassium ions in potassium chloride using the method of example 2;
FIG. 3 is a linear voltammogram of a polyamide membrane measured for mass transfer resistance to chloride ions in potassium chloride using the method of example 3;
FIG. 4 is a linear voltammogram of a polyamide membrane measured for mass transfer resistance to chloride ions in potassium chloride using the method of example 4;
FIG. 5 is a linear voltammogram of a polyamide membrane measured for mass transfer resistance to chloride ions in potassium chloride using the method of example 5.
Reference numerals:
1. The device comprises a first electrolytic cell body, a second electrolytic cell body, a working electrode, a recording electrode, a counter electrode, a Rujin capillary tube, a threaded sleeve, a gasket, a fixing rod, a cover plate, a measuring cell, a polyamide membrane, an ion exchange membrane, an electrochemical workstation and a reference electrode.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the invention and practice it.
The first object of the invention is to provide a device for measuring single ion mass transfer resistance of a polyamide membrane, which comprises an electrochemical working station 14 and a measuring cell 11, wherein a first signal end of the electrochemical working station 14 is connected with a working electrode 3 and a recording electrode 4, a second signal end of the electrochemical working station 14 is connected with a counter electrode 5 and a reference electrode 15, the measuring cell 11 comprises a first electrolytic cell body 1, a second electrolytic cell body 2 and a gasket 8 arranged between the first electrolytic cell body 1 and the second electrolytic cell body 2, the polyamide membrane 12 and the ion exchange membrane 13 are arranged on the gasket 8, the polyamide membrane 12 is positioned on one side close to the first electrolytic cell body 1, the ion exchange membrane 13 is positioned on the other side close to the second electrolytic cell body 2, the first electrolytic cell body 1 is provided with a first cavity used for containing a solution to be measured, the working electrode 3 and the recording electrode 4 extend into the first cavity, the second electrolytic cell body 2 is provided with a second cavity used for containing the solution to be measured, and the counter electrode 5 and the reference electrode 15 extend into the second cavity. That is, the separated polyamide membrane 12 was tested using an electrochemical technique based on a four-electrode system. By taking the electric field as a driving force, cations and anions are separated, so that the cations and anions pass through the dense sub-nano-pore polyamide membrane 12 and the corresponding ion exchange membrane 13, and quantitative and accurate testing of single ion mass transfer resistance is realized. The device disclosed by the invention is simple and effective to operate and has good detection stability.
In some embodiments of the present invention, the length L of the cavity of the first electrolytic cell body 1 or the second electrolytic cell body 2 is 40-70 mm, the width B is 30-50 mm, the height H is 40-80 mm, and the first electrolytic cell body 1 and the second electrolytic cell body 2 may be made of acrylic materials, for example.
In some embodiments of the present invention, the end of the working electrode 3 and the end of the counter electrode 5 are formed as sheet-shaped platinum electrodes or sheet-shaped titanium electrodes, the reference electrode 15 and the recording electrode 4 are Ag/AgCl electrodes, and the effective surface area of the polyamide film 12 is smaller than that of the sheet-shaped platinum electrodes or sheet-shaped titanium electrodes. This is to take into account that the effective surface area of the polyamide membrane 12 is smaller than the surface area of the sheet platinum or sheet titanium electrodes, helping to ensure uniform transfer of ions across the membrane. As an embodiment of the present invention, the effective surface area of the polyamide film 12 is 1 to 4 cm 2.
In some embodiments of the invention, the recording electrode 4 is positioned on one side close to the polyamide membrane 12, the reference electrode 15 is positioned on one side far away from the ion exchange membrane 13, the top parts of the first electrolytic cell body 1 and the second electrolytic cell body 2 are respectively provided with a cover plate 10, the cover plate 10 is provided with a first through hole and a second through hole, threaded sleeves 7 are arranged in the first through hole and the second through hole, one threaded sleeve 7 is used for installing the working electrode 3 and/or the counter electrode 5, a Rugold capillary 6 is arranged in the other threaded sleeve 7, and the reference electrode 15 and/or the recording electrode 4 are arranged in the Rugold capillary 6. By fixing the reference electrode 15 and/or the recording electrode 4 by means of the rujin capillary 6 and the threaded sleeve 7, the stability of the recording spot during the test can be enhanced.
In some embodiments of the present invention, a rotary stirrer may be disposed at the bottoms of the first electrolytic cell body 1 and the second electrolytic cell body 2, respectively, so as to maintain the stable state of the solution to be tested on both sides of the polyamide membrane 12.
In some embodiments of the invention, the Rumex capillary tube 6 is an L-shaped sand core salt bridge or an L-shaped Rumex capillary tube 6, and the distance between the elbow outlet of the Rumex capillary tube 6 and the surface of the polyamide membrane 12 is 1-2 mm.
In some embodiments of the present invention, the fixing bars 9 are further included, and the fixing bars 9 include four fixing bars 9 penetrating through the gasket 8 to connect the first electrolytic cell body 1 and the second electrolytic cell body 2. The first electrolytic cell body 1 and the second electrolytic cell body 2 are connected through the fixing rod 9 and are connected for installing the gasket 8, so that the fixing connection function is achieved on one hand, the guiding function is achieved on the other hand, and the installation accuracy of the polyamide membrane 12 and the ion exchange membrane 13 on the first electrolytic cell body 1, the second electrolytic cell body 2 and the gasket 8 is improved.
A second object of the present invention is to provide a method for measuring the single ion mass transfer resistance of a polyamide membrane, comprising the steps of S1, providing a device as described in any one of the above, attaching a polyamide membrane 12 to an ion exchange membrane 13 of the device, injecting a solution to be measured into a first electrolytic cell 1 and a second electrolytic cell 2 of the device, S2, starting an electrochemical workstation 14 of the device, measuring a current-potential difference spectrum of the single ion transmembrane, and calculating a positive/negative ion mass transfer resistance value by fitting a slope.
The working mechanism of the device for measuring the single ion mass transfer resistance of the polyamide membrane is that positive potential can be applied to a working electrode 3 by utilizing an electrochemical workstation 14, at the moment, the cation exchange membrane 13 is selected as the cation exchange membrane, positively charged ions in a solution to be measured pass through the polyamide membrane 12 and the cation exchange membrane with compact sub-nano holes under the action of an electric field and migrate to a counter electrode 5, potential difference changes on two sides of the membrane are recorded by an Ag/AgCl reference electrode 15 in a Rumex capillary 6, slope fitting is carried out on the obtained current-potential difference map, the derivative of the slope is the resistance of cation transmembrane mass transfer, under the same condition, the cation exchange membrane is used as a contrast, at the moment, negative potential can also be applied to the working electrode 3 by utilizing the electrochemical workstation 14, at the moment, the anion exchange membrane 13 is selected as the anion exchange membrane, negatively charged ions in the solution to be measured pass through the polyamide membrane 12 and the anion exchange membrane with compact sub-nano holes under the action of the electric field and migrate to the counter electrode 5, the slope fitting is carried out on the obtained current-potential difference through the change on two sides of the membrane is recorded by an Ag/AgCl reference electrode 15 in the Rumex 6, and the slope is used as the resistance of the anion membrane under the contrast condition.
In some embodiments of the present invention, step S1 further comprises immersing the ion exchange membrane 13 in the solution to be tested for 12-72 hours before using the ion exchange membrane 13;
the polyamide membrane 12 is a composite polyamide membrane, and before the composite polyamide membrane is used, the composite polyamide membrane is soaked in an alcohol solution for 30-120 min or
Immersing the composite polyamide membrane in ultrapure water for 12-72 h;
the alcohol solution is one or more of ethanol, methanol and isopropanol, and the volume fraction of the alcohol solution is 10% -40%.
In the step S1, the device is installed by (1) preparing a polyamide membrane 12, bonding the polyamide membrane 12 or the soaked polyamide composite membrane and an ion exchange membrane 13 soaked by a solution to be tested, clamping the polyamide membrane or the soaked polyamide composite membrane between a first electrolytic cell body 1 and a second electrolytic cell body 2, (2) adding the solution to be tested, respectively adding the solution to be tested into the first electrolytic cell body 1 and the second electrolytic cell body 2, ensuring that the solution to be tested completely covers the end part of a working electrode 3 and the end part of a counter electrode 5, (3) installing the electrode, connecting a sheet platinum electrode or a sheet titanium electrode and an Ag/AgCl recording electrode 4 positioned at the end part of the working electrode 3 to a first signal end of an electrochemical workstation 14, and connecting a sheet platinum electrode or a sheet titanium electrode and an Ag/AgCl reference electrode 15 positioned at the end part of the counter electrode 5 to a second signal end of the electrochemical workstation 14.
In the step S2, the measurement steps comprise (1) setting working parameters of an electrochemical working station 14, namely setting experimental parameters on the electrochemical working station 14, applying working voltage or working current, wherein the working voltage of the electrochemical working station 14 is 50 mV-50 mV, the sweeping speed is 0.1 mV/S-100 mV/S, the working current of the electrochemical working station 14 is 0.1mA/cm 2~1mA/cm2, the application time is 20-60S, (2) recording data, namely recording the obtained current-potential difference map, and (3) analyzing the data, namely performing linear fitting, and calculating the mass transfer resistance value of cations or anions through fitting slope.
In some embodiments of the invention, the concentration of the solution to be measured is 0.01 mM-1000 mM, the cations in the solution to be measured are one or more of Li+、Na+、K+、Rb+、Cs+、NH4 +、Ca2+、Mg2+、Ba2+, and the anions in the solution to be measured are one or more of Cl -、SO4 2-、NO3 -、PO4 3-、CO3 2- and ClO 4 -.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
Example 1
Referring to fig. 1, a schematic structural diagram of a device for measuring a single ion mass transfer resistance of a polyamide membrane is provided in this embodiment, and the device comprises an electrochemical workstation 14 and a measuring cell 11, wherein a first signal end of the electrochemical workstation 14 is connected with a working electrode 3 and a recording electrode 4, a second signal end of the electrochemical workstation 14 is connected with a counter electrode 5 and a reference electrode 15, the measuring cell 11 comprises a first electrolytic cell body 1, a second electrolytic cell body 2 and a gasket 8 arranged between the first electrolytic cell body 1 and the second electrolytic cell body 2, the gasket 8 is provided with the polyamide membrane 12 and the ion exchange membrane 13, the polyamide membrane 12 is positioned on one side close to the first electrolytic cell body 1, the ion exchange membrane 13 is positioned on the other side close to the second electrolytic cell body 2, the first electrolytic cell body 1 is provided with a first cavity for containing a solution to be measured, the working electrode 3 and the recording electrode 4 are stretched into the first cavity, the second electrolytic cell body 2 is provided with a second cavity for containing the solution to be measured, and the counter electrode 5 and the reference electrode 15 are stretched into the second cavity.
The end part of the working electrode 3 and the end part of the counter electrode 5 adopt platinum sheets with the size of 3 cm multiplied by 3 cm, the platinum sheets are respectively arranged on the outer sides of the first electrolytic cell body 1 and the second electrolytic cell, the Rumex capillary 6 is a commercial L-shaped sand core salt bridge, the Ag/AgCl recording electrode 4 and the Ag/AgCl reference electrode 15 are respectively arranged in the corresponding Rumex capillary 6, meanwhile, the Rumex capillary 6 is filled with potassium chloride with the concentration of 3M, the Rumex capillary 6 is respectively arranged on the inner sides of the first electrolytic cell body 1 and the second electrolytic cell, and the polyamide membrane 12, the ion exchange membrane 13 and the second electrolytic cell body 2 on the first electrolytic cell body 1 and the gasket 8 are connected by utilizing four fixing rods 9, so that the measuring cell 11 of a four-electrode system is formed. Notably, the centers of the platinum sheet, the outlet of the rujin capillary tube 6, the polyamide membrane and the ion exchange membrane 13 are kept on the same horizontal line, ensuring the accuracy and reliability of the experiment.
Example 2
The embodiment specifically provides a method for measuring mass transfer resistance of a polyamide membrane to potassium ions, which comprises the following specific steps:
(1) The commercial NF90 polyamide membrane was immersed in 25% v/v isopropyl alcohol for 30 min, then washed three times with ultrapure water, each immersion for 8 h, then the nonwoven fabric support layer of the commercial NF90 polyamide membrane was peeled off, the CMX cation exchange membrane was immersed in 50mM KCl solution for 24 and h, and the nonwoven fabric support layer of the commercial NF90 polyamide membrane was attached to the immersed CMX cation exchange membrane.
(2) 50ML of 50mM KCl solution was added to the first and second electrolytic cell bodies, respectively, to ensure complete coverage of the solution with 3 cm X3 cm platinum sheets.
(3) The platinum sheet and Ag/AgCl recording electrode at the end of the working electrode were connected to a first signal terminal of the electrochemical workstation, and the platinum sheet and Ag/AgCl reference electrode at the end of the counter electrode were connected to a second signal terminal of the electrochemical workstation.
(4) Setting experimental parameters on an electrochemical workstation, measuring current and potential difference patterns of a potassium ion transmembrane by adopting a linear sweep voltammetry, setting the initial voltage and the termination voltage to be 0mV and 5mV respectively, setting the sweep rate to be 0.5mV/s, and continuously testing for three times until a test system is stable.
(5) Recording the obtained current-potential difference map (scatter diagram) by an electrochemical workstation, performing linear fitting, calculating the mass transfer resistance value of potassium ions by fitting the derivative of the slope, measuring the mass transfer resistance value of potassium ions only containing CMX cation exchange membranes under the same condition, wherein the difference value of the resistances is the transmembrane resistance of potassium ions passing through the commercial NF90 polyamide membrane, and the test result is shown in figure 2.
As can be seen from fig. 2, the slope of the commercial NF90 polyamide membrane bonded with the CMX cation exchange membrane is smaller than that of the CMX cation exchange membrane alone, and the mass transfer resistance of the commercial NF90 polyamide membrane to potassium ions is 32.7 Ω cm 2 as obtained by linear fitting analysis.
Example 3
The embodiment provides a method for measuring mass transfer resistance of a polyamide membrane to chloride ions, which comprises the following specific steps:
(1) The commercial NF90 polyamide membrane was immersed in 25% v/v isopropyl alcohol for 30 min, then washed three times with ultrapure water, each immersion for 8 h, then the nonwoven fabric support layer of the commercial NF90 polyamide membrane was peeled off, the AMX anion exchange membrane was immersed in 50mM KCl solution for 28 h, and the nonwoven fabric support layer of the commercial NF90 polyamide membrane was attached to the immersed AMX anion exchange membrane.
(2) 50ML of 50mM KCl solution was added to the first and second electrolytic cell bodies, respectively, to ensure that the solution completely covered the 3 cm X3 cm platinum sheet.
(3) The platinum sheet and Ag/AgCl recording electrode at the end of the working electrode were connected to a first signal terminal of the electrochemical workstation, and the platinum sheet and Ag/AgCl reference electrode at the end of the counter electrode were connected to a second signal terminal of the electrochemical workstation.
(4) Setting experimental parameters on an electrochemical workstation, measuring the current and potential difference patterns of a chloride ion transmembrane by adopting a linear sweep voltammetry, setting the test parameters to be 0mV and-5 mV for initial voltage and termination voltage respectively, and continuously testing for three times until a test system is stable, wherein the sweep rate is 0.5 mV/s.
(5) Recording the obtained current-potential difference map (scatter diagram) by an electrochemical workstation, performing linear fitting, calculating the mass transfer resistance value of chloride ions by fitting the derivative of the slope, measuring the mass transfer resistance value of chloride ions only containing AMX anion exchange membranes under the same condition, wherein the difference value of the resistances is the transmembrane resistance of chloride ions passing through a commercial NF90 polyamide membrane, and the test result is shown in figure 3.
It can be found from fig. 3 that the slope of the commercial NF90 polyamide membrane bonded with the AMX anion-exchange membrane is smaller than that of the AMX anion-exchange membrane alone, and the mass transfer resistance of the commercial NF90 polyamide membrane to chloride ions is 28.2 Ω cm 2 by linear fitting.
Example 4
The embodiment provides a method for measuring mass transfer resistance of a polyamide membrane to sodium ions, which comprises the following specific steps:
(1) Soaking a commercial NF90 polyamide membrane in 25% v/v isopropanol for 30 min, washing with ultrapure water three times, soaking for 8 h times, peeling off a non-woven fabric supporting layer of the commercial NF90 polyamide membrane, soaking the CMX cation exchange membrane in a 100 mMNa 2SO4 solution for 24 hours, and attaching the non-woven fabric supporting layer of the commercial NF90 polyamide membrane to the soaked CMX cation exchange membrane.
(2) 50ML of 100mM Na 2SO4 solution was added to each of the first and second electrolytic cell bodies to ensure that the solution completely covered the platinum sheet of 3 cm X3 cm.
(3) The platinum sheet and Ag/AgCl recording electrode at the end of the working electrode were connected to a first signal terminal of the electrochemical workstation, and the platinum sheet and Ag/AgCl reference electrode at the end of the counter electrode were connected to a second signal terminal of the electrochemical workstation.
(4) Setting experimental parameters on an electrochemical workstation, measuring current and potential difference patterns of a sodium ion transmembrane by adopting a linear sweep voltammetry, setting the initial voltage and the termination voltage to be 0mV and 5mV respectively, and continuously testing for three times until a test system is stable, wherein the sweep rate is 0.5 mV/s.
(5) Recording the obtained current-potential difference map (scatter diagram) by an electrochemical workstation, performing linear fitting, calculating the mass transfer resistance value of sodium ions by fitting the derivative of the slope, measuring the mass transfer resistance value of sodium ions of the CMX cation exchange membrane only under the same condition, wherein the difference value of the resistances is the transmembrane resistance of sodium ions passing through the commercial NF90 polyamide membrane, and the test result is shown in figure 4.
It can be seen from fig. 4 that the slope of the commercial NF90 polyamide membrane bonded CMX cation exchange membrane is less than the slope of the CMX cation exchange membrane alone. The mass transfer resistance of the commercial NF90 polyamide membrane to sodium ions is 14.3 Ω cm 2 through linear fitting analysis.
Example 5
The embodiment provides a method for measuring mass transfer resistance of a polyamide membrane to sulfate ions, which comprises the following specific steps:
(1) Soaking commercial NF90 polyamide membrane in 25% v/v isopropanol for 30 min, washing with ultrapure water three times, soaking for 8 h times, peeling off non-woven fabric support layer of commercial NF90 polyamide membrane, soaking AMX anion exchange membrane in 100mM Na 2SO4 solution for 24h, and attaching non-woven fabric support layer of commercial NF90 polyamide membrane on soaked AMX anion exchange membrane.
(2) 50ML of 100mM Na 2SO4 solution was added to each of the first and second electrolytic cell bodies to ensure that the solution completely covered the platinum sheet of 3 cm X3 cm.
(3) The platinum sheet and Ag/AgCl recording electrode at the end of the working electrode were connected to a first signal terminal of the electrochemical workstation, and the platinum sheet and Ag/AgCl reference electrode at the end of the counter electrode were connected to a second signal terminal of the electrochemical workstation.
(4) Setting experimental parameters on an electrochemical workstation, measuring the current and potential difference patterns of sulfate ion transmembrane by adopting a linear sweep voltammetry, setting the initial voltage and the termination voltage to be 0mV and-5 mV respectively, and continuously testing for three times until a test system is stable, wherein the sweep rate is 0.5 mV/s.
(5) Recording the obtained current-potential difference map (scatter diagram) by an electrochemical workstation, performing linear fitting, calculating the mass transfer resistance value of sulfate ions by fitting the derivative of the slope, and under the same condition, measuring the mass transfer resistance value of sulfate ions only containing AMX anion exchange membranes, wherein the difference value of the two resistances is the transmembrane resistance of sulfate ions passing through the commercial NF90 polyamide membrane. The test results are shown in FIG. 5.
It can be found from fig. 5 that the slope of the commercial NF90 polyamide membrane bonded with the AMX anion exchange membrane is smaller than that of the AMX anion exchange membrane alone, and the mass transfer resistance of the commercial NF90 polyamide membrane to sulfate ions is 19.4 Ω cm 2 by linear fitting.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations and modifications of the present invention will be apparent to those of ordinary skill in the art in light of the foregoing description. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.
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