A method for the separate characterization of the cathode and anode membrane layers of a bipolar membrane

Abstract

The application discloses a method for distinguishing and characterizing a cathode membrane layer and an anode membrane layer of a bipolar membrane, which comprises the following steps: 1) contacting a first delaminating liquid with an anode membrane side of the bipolar membrane, contacting a second delaminating liquid with a cathode membrane side of the bipolar membrane, and separating the first delaminating liquid and the second delaminating liquid by the bipolar membrane, and meanwhile, peeling the bipolar membrane into an anode membrane and a cathode membrane under a forward power-on condition; 2) alternately immersing the cathode membrane layer and the anode membrane layer obtained in the step 1) in a cleaning acid liquid and a cleaning alkali liquid; and 3) respectively characterizing selectivity of the anode membrane layer and selectivity of the cathode membrane layer obtained after the treatment in the step 2). The method can evaluate the selectivity of the cathode membrane layer and the anode membrane layer of the bipolar membrane separately, can calculate the selectivity of the cathode membrane layer and the anode membrane layer of the bipolar membrane respectively, can provide basic data support for studying different influences of overall performances of the materials and internal reaction mechanisms of the materials, and can provide strong support for improving a preparation process of the bipolar membrane and verifying a structure of the bipolar membrane.

Description

Technical Field

[0001] This invention relates to the field of bipolar membrane technology, and more specifically, to a method for distinguishing and characterizing the anion membrane layer and the cation membrane layer of a bipolar membrane. Background Technology

[0002] Bipolar membrane electrodialysis (BMED) is a method for producing and separating acidic and alkaline solutions from a mixed solution using an electric field. This technology has attracted widespread attention in the field of acid and base preparation due to its advantages such as simple operation, high efficiency, and the absence of any chemical reagents. The bipolar membrane consists of an anion exchange membrane, a catalyst layer, and a cation exchange membrane. It has the function of producing a phenomenon known as hydrolysis: by applying a voltage across the bipolar membrane immersed in an aqueous solution, water within the membrane is dissociated into protons and hydroxide ions. Utilizing this function, bipolar membranes can be combined with cation exchange membranes and anion exchange membranes for electrodialysis, for example, to produce acids and bases from neutral salts.

[0003] Characterizing bipolar membranes has the following important significance: From the perspective of product application, characterizing the energy consumption, selectivity and other properties of bipolar membranes helps to select products according to the actual application requirements; from the perspective of product development and production, characterizing the various properties of bipolar membranes helps to develop and produce high-performance products in a targeted manner.

[0004] Existing technologies can only characterize the selectivity of bipolar films holistically. For example, the mass transfer performance of bipolar films can be characterized by measuring the current efficiency of bipolar films. There is currently no method to characterize the individual anion and cation layers separately, which has brought a major obstacle to the development of bipolar films. Summary of the Invention

[0005] To address the aforementioned deficiencies in the prior art, this invention provides a method for distinguishing and characterizing the anion and cation layers of a bipolar membrane. This method can evaluate the selectivity of the anion and cation layers of the bipolar membrane separately, and only requires a membrane sample of tens of square centimeters to obtain sample information. It has the advantages of wide applicability, accuracy, and high efficiency.

[0006] To achieve the above-mentioned objective, this invention provides a method for distinguishing and characterizing the anion film layer and cation film layer of a bipolar membrane, comprising:

[0007] 1) The anodic side of the bipolar membrane is contacted with the first layered liquid, and the anion side of the bipolar membrane is contacted with the second layered liquid. The bipolar membrane separates the first layered liquid and the second layered liquid, and at the same time, under the condition of forward energization, the bipolar membrane is peeled into an anode membrane and a cathode membrane.

[0008] 2) Immerse the anion membrane layer and cation membrane layer obtained in step 1) alternately with cleaning acid solution and cleaning alkali solution;

[0009] 3) The selectivity of the cation and anion films obtained after step 2) was characterized respectively;

[0010] The first layered solution is a mixed solution containing acid and metal ions, and the second layered solution is an alkaline solution.

[0011] Furthermore, the first layered solution is a mixed solution of acid and aqueous solution containing metal ions.

[0012] Furthermore, the acid solution is selected from one or more of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid; the metal ion is selected from Al. 3+ Fe 3+ Cu 2+ Mg 2+ One or more of them.

[0013] Furthermore, in the second layered liquid, the alkaline solution is selected from one or more of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and lithium hydroxide aqueous solution.

[0014] Further, the concentration of the acid solution is 0.1N-0.5N, the concentration of the aqueous solution containing metal ions is 0.1N-0.5N, and the concentration of the alkaline solution is 0.3N-3N.

[0015] Furthermore, in step 1), the forward current density is 400-1500 A / m. 2 The power-on time is 15-120 minutes.

[0016] Further, in step 2), the concentration of the cleaning acid or cleaning alkali is 1-5N; the alternation process is to first soak the membrane in the cleaning acid for 0.5-6 hours, then clean the membrane with pure water, and then soak it in the cleaning alkali for 0.5-6 hours, repeating this alternation multiple times, and finally washing the membrane with pure water.

[0017] Preferably, the cleaning acid solution is selected from one or more of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid;

[0018] Preferably, the cleaning alkaline solution is selected from one or more of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and lithium hydroxide aqueous solution.

[0019] Further, in step 3), the selectivity of the cation film layer is characterized using a cation film layer selectivity measuring device. The characterization method includes: contacting one side of the cation film layer with a first cation film layer measuring solution and the other side with a second cation film layer measuring solution, with the cation film layer separating the first and second cation film layer measuring solutions, and performing characterization tests under energized conditions.

[0020] Furthermore, the first cation exchange membrane assay solution and the second cation exchange membrane assay solution are alkaline solutions with different concentrations.

[0021] Furthermore, the first cation exchange membrane assay solution is one or more of a 2-6N aqueous solution of sodium hydroxide, potassium hydroxide, and lithium hydroxide, and the second cation exchange membrane assay solution is one or more of a 0-0.1N aqueous solution of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0022] Further, in step 3), the selectivity of the anion membrane layer is characterized using an anion membrane layer selectivity measuring device. The characterization method includes: contacting one side of the anion membrane layer with a first anion membrane layer measuring solution and the other side with a second anion membrane layer measuring solution, with the anion membrane layer separating the first and second anion membrane layer measuring solutions, and performing characterization tests under energized conditions.

[0023] Furthermore, the first and second anion membrane assay solutions are acid solutions with different concentrations.

[0024] Furthermore, the first anion membrane assay solution is one or more of 0-0.1N dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid; the second anion membrane assay solution is one or more of 1-5N dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid.

[0025] Furthermore, the current density of the energized circuit is 400-1500 A / m. 2 The power-on time is 8-30 hours.

[0026] Furthermore, in step 3), the selective permeation performance of the cathode or anolyte is characterized by a selectivity coefficient as shown in the following formula:

[0027]

[0028] Where A is the selection coefficient.

[0029] C0 is dilute acid solution H + Or dilute alkaline solution OH - Initial concentration, mol / L

[0030] C t dilute acid solution H + Or dilute alkaline solution OH - The final concentration, mol / L

[0031] V is the volume of the dilute acid or dilute alkali solution, in mL.

[0032] I represents the current, A.

[0033] t is the energizing time, s

[0034] F is the Faraday constant, 96485 C / mol.

[0035] The beneficial effects of this invention are as follows:

[0036] This invention provides a method for distinguishing and characterizing the anion and cation layers of a bipolar membrane. First, the bipolar membrane is peeled into an anodic and a cathode membrane using a first and second layering solution under forward energization. Then, the anion and cation layers are alternately immersed in cleaning acid and cleaning alkali solutions to remove residual catalyst layers from the surface. Finally, the selectivity of the resulting cation and anion layers is characterized separately. Therefore, this method can independently evaluate the selectivity of the anion and cation layers of a bipolar membrane. Selectivity directly affects the membrane's current efficiency and unit throughput, among other properties. This invention allows for the separate calculation of the selectivity of the anion and cation layers, providing fundamental data support for the study of their different impacts on the overall material performance and the internal reaction mechanisms of the material. It also provides strong support for improving the bipolar membrane fabrication process and verifying its structure.

[0037] Other features and advantages of the present invention will be described in detail through the following specific embodiments. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the bipolar film layering device provided in an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of the anion membrane selectivity testing device provided in an embodiment of the present invention.

[0040] Figure 3 This is a schematic diagram of the cation membrane selectivity testing device provided in an embodiment of the present invention. Detailed Implementation

[0041] The following will clearly and completely describe the concept and technical effects of this application in conjunction with embodiments, so as to fully understand the purpose, features and effects of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are all within the scope of protection of this application.

[0042] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0043] This invention provides a method for distinguishing and characterizing the anion film layer and cation film layer of a bipolar membrane, comprising:

[0044] 1) The anodic side of the bipolar membrane is contacted with the first layered liquid, and the anion side of the bipolar membrane is contacted with the second layered liquid. The bipolar membrane separates the first layered liquid and the second layered liquid, and at the same time, under the condition of forward energization, the bipolar membrane is peeled into an anode membrane and a cathode membrane.

[0045] 2) Immerse the anion membrane layer and cation membrane layer obtained in step 1) alternately with cleaning acid solution and cleaning alkali solution;

[0046] 3) The selectivity of the cation and anion films obtained after step 2) was characterized respectively;

[0047] The first layer solution is a mixed solution containing acid and iron ions, and the second layer solution is an alkaline solution. The purpose of this arrangement is to generate heat and water between the anion and cation membrane layers and to generate new substances that promote membrane separation.

[0048] In some specific implementations, a layering device is used for bipolar membrane separation in step 1), for example, referring to... Figure 1 As shown, the stratification device contains a first stratifying liquid and a second stratifying liquid, and a bipolar membrane is placed inside the device to separate the first and second stratifying liquids. Specifically, the bipolar membrane can be placed inside the device first, and then the first and second stratifying liquids can be added to both sides of the bipolar membrane, respectively.

[0049] In some specific embodiments, the first layered solution is a mixture of acid and aqueous solution containing metal ions.

[0050] For example, in the first layered solution, the acid is selected from one or more of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid; the metal ions are selected from Al. 3+ Fe 3+ Cu 2+ Mg 2+ One or more of them.

[0051] For example, in the second layered liquid, the alkaline solution is selected from one or more of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and lithium hydroxide aqueous solution.

[0052] In some specific embodiments, the concentration of the acid solution is 0.1N-0.5N, the concentration of the aqueous solution containing metal ions is 0.1N-0.5N, and the concentration of the alkaline solution is 0.3N-3N. The purpose of setting the concentrations as described above is to enable bubbling separation between the membrane layers without damaging the membrane structure.

[0053] In some specific implementations, in step 1), the forward current density is 400-1500 A / m. 2 The energizing time is 15-120 minutes. The purpose of this setting is to allow the bubbles between the membrane layers to separate without damaging the membrane structure.

[0054] In some specific embodiments, in step 2), the anion membrane layer and the cation membrane layer obtained in step 1) are alternately soaked with cleaning acid and cleaning alkali solutions. The anion membrane layer and the cation membrane layer can be soaked together in the same container simultaneously, or they can be soaked separately. The purpose of soaking is to remove any catalyst that may be present on the surface of the membrane layers.

[0055] In some specific embodiments, in step 2), the concentration of the cleaning acid or cleaning alkali is 1-5N; the alternation process is to first soak the membrane in the cleaning acid for 0.5-6 hours, then clean the membrane with pure water, and then soak it in the cleaning alkali for 0.5-6 hours, repeating this alternation multiple times, and finally washing the membrane with pure water, for example, three times.

[0056] Preferably, the cleaning acid is selected from one or more of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid;

[0057] Preferably, the cleaning alkaline solution is selected from one or more of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and lithium hydroxide aqueous solution.

[0058] In some specific embodiments, in step 3), the selectivity of the cation film layer is characterized using a cation film layer selectivity measuring device. The characterization method includes: contacting one side of the cation film layer with a first cation film layer measuring solution and the other side with a second cation film layer measuring solution, with the cation film layer separating the first and second cation film layer measuring solutions, and performing the characterization test under energized conditions. For example, see reference... Figure 2 As shown, the cation film selective determination device contains a first cation film determination solution and a second cation film determination solution, with the anode membrane placed inside the device to separate the first and second cation film determination solutions. Specifically, the anode membrane can be placed inside the device first, and then the first and second cation film determination solutions can be added to both sides of the anode membrane, respectively.

[0059] In some specific embodiments, the first and second cation exchange layer assay solutions are alkaline solutions of different concentrations. This arrangement aims to simulate the state of the cation exchange layer in actual application to more accurately characterize its selectivity.

[0060] In some specific embodiments, the first cation exchange layer determination solution is one or more of a 2-6N dilute sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and lithium hydroxide aqueous solution, and the second cation exchange layer determination solution is one or more of a 0-0.1N dilute sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and lithium hydroxide aqueous solution, and its concentration can be infinitely small.

[0061] In some specific embodiments, in step 3), the selectivity of the anion membrane layer is characterized using an anion membrane layer selectivity measuring device. The characterization method includes: contacting one side of the anion membrane layer with a first anion membrane layer measuring solution and the other side with a second anion membrane layer measuring solution, with the anion membrane layer separating the first and second anion membrane layer measuring solutions, and performing the characterization test under energized conditions. For example, see reference... Figure 3 As shown, the anion membrane selective determination device is used to contain the first anion membrane determination solution and the second anion membrane determination solution, and the cathode membrane is placed inside the device to separate the first anion membrane determination solution and the second anion membrane determination solution. Specifically, the cathode membrane can be placed inside the device first, and then the first anion membrane determination solution and the second anion membrane determination solution can be added to both sides of the cathode membrane respectively.

[0062] In some specific embodiments, the first and second anion exchange membrane assay solutions are acid solutions of different concentrations. This arrangement aims to simulate the state of the anion exchange membrane in actual application to more accurately characterize its selectivity.

[0063] In some specific embodiments, the first anion membrane layer test solution is one or more of 0-0.1N dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid, and its concentration can be infinitely small; the second anion membrane layer test solution is one or more of 1-5N dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid.

[0064] In some specific embodiments, the current density in the characterization method is 400-1500 A / m. 2 The power-on time is 8-30 hours. The purpose of this setting is to simulate the state of the membrane layer in actual application and to visualize the differences between products, so as to accurately characterize the selectivity of the membrane layer.

[0065] In some specific implementations, in step 3), the characterization test uses a selection coefficient as shown in the following formula to characterize the cathode or anode film.

[0066]

[0067] Where A is the selection coefficient.

[0068] C0 is dilute acid solution H + Or dilute alkaline solution OH - Initial concentration, mol / L

[0069] C t dilute acid solution H + Or dilute alkaline solution OH - The final concentration, mol / L

[0070] V is the volume of the dilute acid or dilute alkali solution, in mL.

[0071] I represents the current, A.

[0072] t is the energizing time, s

[0073] F is the Faraday constant, 96485 C / mol.

[0074] In this invention, the aforementioned selectivity coefficient can be used to characterize the selective permeation performance of each layer of the bipolar membrane for hydrogen ions and hydroxide ions.

[0075] The present invention will be further illustrated by the following examples, but the present invention is not limited thereto.

[0076] Example 1: Take a commercially available bipolar membrane 1, take samples of 4*7cm (effective area 2*5cm), and place them in... Figure 1 In the layering device shown, layering solution 1 uses 100 mL of a mixed solution of 0.2 N dilute sulfuric acid and 0.3 N ferric chloride aqueous solution in equal proportion, and layering solution 2 uses 100 mL of 0.5 N dilute sodium hydroxide solution. The solution is energized at 1 A for 1 h to obtain a bipolar membrane with completely separated anion and cation layers.

[0077] Comparative Example 1: Using a 2-chamber unit with the following structure, at a liquid temperature of 25°C and a current density of 30 A / dm³... 2 Under certain conditions, after 5 hours of energization, the bipolar membrane produces dense small bubbles, possibly because the process of producing water and heat alone is insufficient to completely separate the anion membrane layer and the cation membrane layer.

[0078] Cathode (Pt plate) (1.0 mol / L NaOH) / Measurement of bipolar membrane / (1.0 mol / L HCl) Anode (Pt plate)

[0079] Comparative Example 2: Take commercially available bipolar membrane 1, and take samples of 4*7cm (effective area 2*5cm) respectively. Place them in... Figure 1 In the layering device shown, layering solution 1 uses 100 mL of a mixture of 0.2 N dilute sulfuric acid and 0.3 N ferric chloride aqueous solution in equal proportions, and layering solution 2 uses 100 mL of 0.5 N dilute sodium hydroxide solution. When the current is constant at 0.1 A for 1 h, the current density is too low, small bubbles form on the bipolar membrane, and the anion membrane layer and cation membrane layer cannot be completely separated.

[0080] By comparing Example 1 with Comparative Examples 1 and 2, it can be seen that the method of this application can completely peel off the anion and cation layers of the bipolar membrane.

[0081] Example 2: The anion membrane layer and cation membrane layer separated in Example 1 were soaked in 2N HCl for 3 hours, washed with pure water, soaked in 2N NaOH for 3 hours, and washed with pure water. This process was repeated three times. The anion membrane layer was then placed in... Figure 3 In the anion membrane selectivity testing device shown, the selectivity coefficient was measured to be 0.95. The cation membrane was placed... Figure 2In the cation exchange membrane selectivity testing device shown, the selectivity coefficient was measured to be 0.86. The first and second anion exchange membrane assay solutions were 0.01N and 3N dilute hydrochloric acid, respectively. The first and second cation exchange membrane assay solutions were 0.001N and 3.5N dilute NaOH solutions, respectively. The power parameters for both the anion exchange membrane selectivity testing device and the cation exchange membrane selectivity testing device included: constant current of 0.8A and power-on time of 30 hours.

[0082]

[0083] In this embodiment, the specific values ​​of the above parameters are I = 0.8 and t = 1.08 * 10^10. 5 F is 96485, V is 0.1, and the cation exchange membrane layer c o It is 3.498, c t The value is 3.051, and the anion membrane layer c o It is 3.012, c t The coefficient of choice is 1.762, from which the above selection coefficient is calculated.

[0084] Although the present invention has been described in detail through the preferred embodiments described above, it should be understood that the above description should not be considered as a limitation of the present invention. Those skilled in the art will understand that modifications or adjustments can be made to the present invention based on the teachings of this specification. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A method for the separate characterization of the cathode and anode membrane layers of a bipolar membrane, characterized in that, The method comprises the following steps: 1) contacting the anode side of the bipolar membrane with a first layered solution, contacting the cathode side of the bipolar membrane with a second layered solution, and separating the first layered solution and the second layered solution by the bipolar membrane, and under the condition of positive current, the bipolar membrane is separated into an anode layer and a cathode layer; 2) alternately immersing the anode layer and the cathode layer obtained in step 1) in cleaning acid and cleaning base; 3) characterizing the selectivity of the anode layer and the cathode layer obtained in step 2) respectively; The first layered solution is a mixed solution containing acid and metal ions, and the second layered solution is a base solution. The metal ion is selected from one or more of Al 3+ , Fe 3+ , Cu 2+ , Mg 2+ .

2. The method for characterizing the cathode and anode layer of a bipolar membrane according to claim 1, characterized in that, The first layered solution is a mixed solution of acid and metal ion-containing aqueous solution. The acid in the first layered solution is selected from one or more of dilute sulfuric acid, dilute hydrochloric acid and dilute nitric acid. The base in the second layered solution is selected from one or more of sodium hydroxide solution, potassium hydroxide solution and lithium hydroxide solution. The concentration of the acid is 0.1N-0.5N, the concentration of the metal ion-containing aqueous solution is 0.1N-0.5N, and the concentration of the base is 0.3N-3N.

3. The method for distinguishing characterization of the cathode and anode layers of a bipolar membrane according to claim 1, characterized in that, In step 1), the current density of the power supply is 400-1500 A / m 2 , and the power supply duration is 15-120 min.

4. The method for the characterization of the cathode and anode layer of a bipolar membrane according to any one of claims 1 to 3, characterized in that, In step 2), the concentration of the cleaning acid or the cleaning base is 1-5N; the alternating process is to immerse in the cleaning acid for 0.5-6h, then wash the membrane with pure water, and then immerse in the cleaning base for 0.5-6h, and so on, and finally wash the membrane with pure water. The cleaning acid is selected from one or more of dilute sulfuric acid, dilute hydrochloric acid and dilute nitric acid. The cleaning base is selected from one or more of sodium hydroxide solution, potassium hydroxide solution and lithium hydroxide solution.

5. The method for distinguishing characterization of the cathode and anode layers of a bipolar membrane according to claim 1, characterized in that, In step 3), the selectivity of the anode layer is characterized by using an anode layer selectivity measuring device, and the characterization method comprises the following steps: one side of the anode layer is contacted with a first anode layer measuring solution, the other side is contacted with a second anode layer measuring solution, the anode layer separates the first anode layer measuring solution and the second anode layer measuring solution, and the characterization test is carried out under the condition of current.

6. The method for the characterization of the cathode and anode layer of a bipolar membrane according to claim 5, characterized in that, The first anode layer measuring solution and the second anode layer measuring solution are alkali solutions with different concentrations. The first anode layer measuring solution is one or more of 2-6N sodium hydroxide solution, potassium hydroxide solution and lithium hydroxide solution, and the second anode layer measuring solution is one or more of 0-0.1N sodium hydroxide solution, potassium hydroxide solution and lithium hydroxide solution.

7. The method for distinguishing characterization of the cathode and anode layers of a bipolar membrane according to claim 1, characterized in that, In step 3), the selectivity of the cathode layer is characterized by using a cathode layer selectivity measuring device, and the characterization method comprises the following steps: one side of the cathode layer is contacted with a first cathode layer measuring solution, the other side is contacted with a second cathode layer measuring solution, the cathode layer separates the first cathode layer measuring solution and the second cathode layer measuring solution, and the characterization test is carried out under the condition of current.

8. The method for characterizing the cathode and anode layer of a bipolar membrane according to claim 7, characterized in that, The first cathode layer measuring solution and the second cathode layer measuring solution are acid solutions with different concentrations. The first cathode layer measuring solution is one or more of 0-0.1N dilute sulfuric acid, dilute hydrochloric acid and dilute nitric acid, and the second cathode layer measuring solution is one or more of 1-5N dilute sulfuric acid, dilute hydrochloric acid and dilute nitric acid.

9. The method for distinguishing characterization of the cathode and anode layer of a bipolar membrane according to claim 5 or 7, characterized in that, The current density of the power supply is 400-1500 A / m 2 , and the power supply duration is 8-30 h.

10. The method for characterizing the cathode and anode layer of a bipolar membrane according to claim 5 or 7, characterized in that, In step 3), the selectivity of the cathode layer or the anode layer is characterized by the selectivity coefficient shown in the following formula: wherein A is the selectivity coefficient. C0 is the initial concentration of the dilute acid H + or dilute base OH - , mol / L C t For the end concentration of the dilute acid H + or dilute base OH - , mol / L V is the volume of dilute acid or dilute base solution, mL I is the current, A t is the current time, s F is the Faraday constant, 96485 C / mol.

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