A method for regenerating amino acid membrane contaminated by copper ions

Abstract

The present invention relates to the technical field of contaminated membrane regeneration, and discloses a method for regenerating an amino acid membrane contaminated by copper ions. The method comprises the following steps: immersing the amino acid membrane contaminated by copper ions in a remover solution; the amino acid membrane is composed of cysteine; the remover is aspartic acid and / or glutamic acid; and the pH value of the remover solution is 5.0 to 5.5. The method of the present invention can effectively remove copper ions from the surface of the amino acid membrane with high removal efficiency and high selectivity for copper ions, thereby regenerating the amino acid membrane contaminated by copper ions and enabling the amino acid membrane to be reused.

Description

Technical Field

[0001] The invention relates to the technical field of contaminated membrane regeneration, in particular to a method for regenerating an amino acid membrane contaminated by copper ions. Background Art

[0002] Heavy metal pollution is an important factor affecting water quality safety. Coal mining, electroplating, textiles, printing and dyeing and other fields will produce a large amount of Cu 2+ 、Hg 2+ 、Cd 2+ , Pb 2+ 、Zn 2+ 、Mn 2+ Once improperly treated wastewater containing heavy metal ions is discharged into natural water bodies, it will cause serious harm to the ecosystem and biological health. Therefore, the development and application of heavy metal ion removal technology in wastewater has always been the research focus of scientific researchers. 2+ It is an indispensable trace element in the human body, which has many physiological functions such as promoting electron transfer, ensuring mitochondrial function and enzyme activity. However, studies have shown that when excessive Cu accumulates in the body 2+ When it is released, it will cause cell death and endanger human health. Among many heavy metal ions, Cu 2+ Its physiological toxicity is second only to Hg 2+ .

[0003] Generally speaking, Cu 2+ The removal methods include flocculation, chemical precipitation, electrochemical method, adsorption, ion exchange and membrane separation technology. Among them, membrane separation technology has been widely used due to its advantages such as simple operation and high treatment efficiency. Common membrane materials include surface-modified polyetherimide membrane, amino ceramic membrane, amino acid membrane, etc. One of the basic principles of membrane separation technology is Cu 2+ By forming chemical bonds with the functional groups on the membrane surface (such as amino, carboxyl, hydroxyl, etc.), it is fixed or adsorbed on the membrane surface, thereby separating from the water body and achieving the purpose of removal. However, in actual applications, due to the 2+ Most of them are stably bound to the surface of the membrane material through chemical coordination bonds. In addition, due to the complexity of the wastewater matrix, membrane pollution and difficulty in membrane regeneration often occur, which greatly reduces the membrane separation efficiency and also brings about problems such as short membrane life, poor reusability, and high economic cost.

[0004] A common method for regenerating copper ion-contaminated membranes is to clean them with an eluent. For example, patent CN101249990A uses a disodium ethylenediaminetetraacetic acid (Na2EDTA) solution as an eluent, which can effectively remove copper ions adsorbed on chitosan-modified nylon membranes. However, Na2EDTA is not very effective in removing copper ions adsorbed on amino acid membranes and has low selectivity. Na2EDTA has a complexing ability for a variety of metal ions, which may cause membrane re-contamination and limit its scope of application. Summary of the Invention

[0005] To address the aforementioned technical issues, namely the difficulty of efficiently removing copper ions adsorbed on amino acid membranes and the low selectivity for copper ions in existing technologies, the present invention provides a method for regenerating amino acid membranes contaminated with copper ions. The method of the present invention effectively removes copper ions from the surface of amino acid membranes with high removal efficiency and high selectivity for copper ions, enabling the regeneration of amino acid membranes contaminated with copper ions and the reuse of the amino acid membranes.

[0006] The specific technical solutions of the present invention are:

[0007] A method for regenerating an amino acid membrane contaminated by copper ions comprises the following steps: immersing the amino acid membrane contaminated by copper ions in a remover solution; the amino acid membrane is composed of cysteine; the remover is aspartic acid and / or glutamic acid; and the pH value of the remover solution is 5.0-5.5.

[0008] The present invention targets a specific membrane amino acid (cysteine), uses aspartic acid and / or glutamic acid as a remover, and cooperates with a specific pH environment (pH value of 5.05~5.50), which can achieve the following effects: under the above conditions, the remover has a negative charge and the membrane surface has a small amount of negative charge, so that a weak electrostatic repulsion can exist between the remover and the membrane surface. At the same time, a strong electrostatic attraction and coordination effect can be formed between the remover and the copper ions. Under the dual synergy of the action between the remover and the membrane and the action between the remover and the copper ions, the coordination bond between the copper ions and the amino acid membrane surface can be induced to break, thereby achieving the purpose of removing the copper ions on the amino acid membrane surface and achieving a higher removal efficiency; and under the above conditions, the binding force between the membrane and the copper ions will not be too strong due to the excessive negative charge on the membrane surface, nor will the copper ions be converted into copper hydroxide due to the excessive alkalinity, thereby aggravating the membrane pollution, which is conducive to the efficient removal of copper ions on the amino acid membrane surface.

[0009] In addition, the remover used in the present invention has a relatively high binding constant with copper ions, and a relatively low binding constant with other common metal ions, so it has a high selectivity for copper ions, which can reduce the risk of membrane re-contamination caused by the remover complexing with other metal ions.

[0010] Preferably, the removal agent is aspartic acid.

[0011] Aspartic acid has moderate rigidity. It will not reduce the probability of electrostatic binding with copper ions on the membrane surface due to excessive flexibility of the molecular chain, nor will it produce a steric effect due to excessive rigidity to hinder its electrostatic interaction with the membrane surface. Therefore, using aspartic acid as a remover can improve the removal efficiency of copper ions on amino acid membranes.

[0012] Preferably, the concentration of the remover solution is 5-10 mmol / L.

[0013] Preferably, the soaking time is not less than 10 min, more preferably 10 to 20 min.

[0014] Preferably, the remover solution is prepared from a remover and a phosphate buffer solution (PBS); the concentration of the phosphate buffer solution is 0.05-0.1 mol / L.

[0015] Preferably, the amino acid membrane is assembled on the surface of a metal electrode; after the copper ion-contaminated amino acid membrane is immersed in a remover solution, scanning electrochemical microscopy and / or cyclic voltammetry are used to detect the copper ion removal effect on the amino acid membrane surface.

[0016] Preferably, the cyclic voltammetry method comprises the following steps: using a metal electrode with an amino acid film on its surface as a working electrode, assembling an electrochemical device together with a counter electrode, a reference electrode, and an electrolyte, performing a forward scan, integrating the copper ion reduction peak to obtain a reduction peak charge, and calculating the rate of decrease in the reduction peak charge after immersing the copper ion-contaminated amino acid film in a remover solution compared to before immersion to obtain a copper ion removal rate. That is, the calculation formula for the copper ion removal rate is as follows:

[0017]

[0018] Wherein, P is the copper ion removal rate; Q o is the peak charge of copper ion reduction before immersion; Q is the peak charge of copper ion reduction after immersion.

[0019] Preferably, the metal electrode is a gold electrode.

[0020] Preferably, the counter electrode is a platinum wire; the reference electrode is an Ag / AgCl electrode; the electrolyte is a phosphate buffer solution (PBS) containing KCl and K4Fe(CN)6; during the forward scan, the electrochemical window is -0.2~0.6 V, and the scan rate is 0.05~0.1 V / s.

[0021] Preferably, the pH value of the electrolyte is 5.0-5.5, the content of KCl is 0.1-0.2 mol / L, and the content of K4Fe(CN)6 is 0.5-2.0 mmol / L.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The present invention targets a specific membrane amino acid (cysteine), uses aspartic acid and / or glutamic acid as a remover, and combines it with a specific pH environment (pH 5.05-5.50), which can effectively remove copper ions from the surface of the amino acid membrane and achieve the regeneration of the copper ion-contaminated amino acid membrane.

[0024] (2) The remover used in the present invention has a high selectivity for copper ions, which can reduce the risk of membrane re-contamination caused by the remover complexing with other metal ions.

[0025] (3) The method of the present invention is used to remove copper ions on the surface of the amino acid membrane. No toxic byproducts are generated during the entire process, making it safer and more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The cyclic voltammograms of the working electrode in Example 1 were measured before and after being immersed in the remover solution.

[0027] Figure 2 This is the surface current distribution diagram of the working electrode with copper ions enriched on the surface in Example 1.

[0028] Figure 3 This is the current distribution diagram on the working electrode surface after the cysteine membrane is regenerated in Example 1.

[0029] Figure 4 This is a curve showing the change in copper ion removal rate with the immersion time in the remover (aspartic acid) solution.

[0030] Figure 5 The cyclic voltammograms are measured before and after immersion in different remover solutions.

[0031] Figure 6 is the copper ion removal efficiency after immersion in different remover solutions. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the embodiments.

[0033] A method for regenerating an amino acid membrane contaminated by copper ions comprises the following steps: immersing the amino acid membrane contaminated by copper ions in a remover solution; the amino acid membrane is composed of cysteine; the remover is aspartic acid and / or glutamic acid; and the pH value of the remover solution is 5.0-5.5.

[0034] In some embodiments, the removal agent is aspartic acid.

[0035] In some specific embodiments, the concentration of the remover solution is 5-10 mmol / L.

[0036] In some embodiments, the soaking time is no less than 10 min.

[0037] In some specific embodiments, the remover solution is prepared from a remover and a phosphate buffer solution (PBS); the concentration of the phosphate buffer solution is 0.05-0.1 mol / L.

[0038] In some embodiments, the amino acid membrane is assembled on the surface of a metal electrode; after the copper ion-contaminated amino acid membrane is immersed in a remover solution, scanning electrochemical microscopy and / or cyclic voltammetry are used to detect the copper ion removal effect on the surface of the amino acid membrane. Optionally or preferably,

[0039] In some specific embodiments, the steps of the cyclic voltammetry method include: using a metal electrode with an amino acid film on its surface as a working electrode, assembling an electrochemical device together with a counter electrode, a reference electrode and an electrolyte, performing a forward scan, integrating the copper ion reduction peak to obtain the reduction peak charge, and calculating the decrease rate of the reduction peak charge after the amino acid film contaminated with copper ions is immersed in a remover solution compared to before immersion to obtain the copper ion removal rate.

[0040] In the above specific implementation manner, optionally or preferably:

[0041] The metal electrode is a gold electrode;

[0042] The counter electrode is a platinum wire;

[0043] The reference electrode is an Ag / AgCl electrode;

[0044] The electrolyte is a phosphate buffer solution (PBS) containing KCl and K4Fe(CN)6, with a pH value of 5.0-5.5, wherein the content of KCl is 0.1-0.2 mol / L, and the content of K4Fe(CN)6 is 0.5-2.0 mmol / L;

[0045] During the forward scan, the electrochemical window is -0.2-0.6 V, and the scan rate is 0.05-0.1 V / s.

[0046] The present invention is described below by way of specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, any changes and advantages that can be imagined by those skilled in the art are included in the present invention, and the scope of protection of the present invention is defined by the appended claims and any equivalents thereof.

[0047] Example 1

[0048] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0049] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 min, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0050] S2: Add aspartic acid to 0.05 mol / L PBS buffer and adjust the pH to 5.50 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with an aspartic acid concentration of 5 mmol / L.

[0051] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 10 minutes, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0052] S4: Scanning electrochemical microscopy was used to evaluate the removal of copper ions from the cysteine membrane on the working electrode. The specific process was as follows: the probe electrode diameter was 10 μm, the distance between the probe and the working electrode was fixed at 10 μm, the probe applied potential was 0.4 V, the working electrode was at open circuit potential, the probe scan rate was 20 μm / s, the scanning range was 50 μm×50 μm, and the surface current distribution was obtained. The surface current distribution of the working electrode with copper ions enriched on the surface in step S1 is shown in Figure 2. Figure 2 As shown in FIG. 3 , the current distribution on the working electrode surface after the cysteine membrane is regenerated in step S3 is as follows: Figure 3 As shown, from Figure 2 and Figure 3 It can be seen that before soaking in the remover solution, the surface current of the working electrode in the scanning range is 1.54~1.59 nA, and the current distribution is uniform; after soaking in the remover solution, the surface current of the working electrode in the scanning range is 1.33~1.36 nA, and the conductivity of the working electrode is significantly lower than before soaking, indicating that the copper ions attached to the cysteine membrane are reduced.

[0053] S5: Cyclic voltammetry was used to evaluate the removal of copper ions from the cysteine membrane surface on the working electrode. The specific process was as follows: a platinum wire was used as the counter electrode and silver / silver chloride (Ag / AgCl) was used as the reference electrode. A 0.05 mol / L PBS buffer solution was used as the electrolytic solution, and 0.1 mol / L KCl was added as the electrolyte, and 1 mmol / L K4Fe(CN)6 was added as the free electroactive species to prepare an electrolyte with a pH of 5.50. The working electrode, counter electrode, reference electrode, and electrolyte were assembled into an electrochemical device. The electrochemical window was -0.2 to 0.6 V, and a positive scan was performed at a scan rate of 0.1 V / s. The cyclic voltammetry test results are as follows:

[0054] (1) When the working electrode with copper ions enriched on the surface in step S1 and the working electrode after the cysteine membrane regeneration in step S3 are used respectively, the cyclic voltammograms obtained are as follows: Figure 1 As shown, it can be seen that before immersion in the remover solution, Cu appeared near 0.24 V and 0.14 V respectively. 2+ / + The redox characteristic peaks of Cu 2+ / + The intensity of the redox characteristic peaks decreased significantly.

[0055] (2) By integrating the copper ion reduction peak in the cyclic voltammogram, the reduction peak charge is obtained, and the copper ion removal rate is calculated according to the following formula:

[0056]

[0057] Wherein, P is the copper ion removal rate; Q o Q is the peak charge of copper ion reduction measured when using the working electrode with copper ions enriched on its surface in step S1; Q is the peak charge of copper ion reduction measured when using the working electrode after the cysteine membrane is regenerated in step S3.

[0058] According to measurement, the copper ion removal rate (P value) using the method of this embodiment is 96.47±0.64%.

[0059] Example 2

[0060] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0061] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0062] S2: Add aspartic acid to 0.05 mol / L PBS buffer and adjust the pH to 5.50 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with an aspartic acid concentration of 8 mmol / L.

[0063] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 10 minutes, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0064] S4: Cyclic voltammetry was used to evaluate the removal of copper ions from the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The copper ion removal rate (P value) using the method of this example was 96.91±0.81%.

[0065] Example 3

[0066] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0067] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0068] S2: Add aspartic acid to 0.05 mol / L PBS buffer and adjust the pH to 5.50 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with an aspartic acid concentration of 10 mmol / L.

[0069] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 10 minutes, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0070] S4: Cyclic voltammetry was used to evaluate the removal of copper ions from the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The copper ion removal rate (P value) using the method of this example was 97.12±0.47%.

[0071] Example 4

[0072] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0073] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0074] S2: Add aspartic acid to 0.05 mol / L PBS buffer and adjust the pH to 5.50 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with an aspartic acid concentration of 5 mmol / L.

[0075] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 5 seconds, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0076] S4: Cyclic voltammetry was used to evaluate the removal of copper ions from the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The copper ion removal rate (P value) using the method of this example was 9.07±3.44%.

[0077] Example 5

[0078] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0079] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0080] S2: Add aspartic acid to 0.05 mol / L PBS buffer and adjust the pH to 5.50 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with an aspartic acid concentration of 5 mmol / L.

[0081] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 30 seconds, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0082] S4: Cyclic voltammetry was used to evaluate the removal of copper ions from the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The copper ion removal rate (P value) using the method of this example was 15.11±0.38%.

[0083] Example 6

[0084] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0085] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0086] S2: Add aspartic acid to 0.05 mol / L PBS buffer and adjust the pH to 5.50 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with an aspartic acid concentration of 5 mmol / L.

[0087] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 1 min, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0088] S4: Cyclic voltammetry was used to evaluate the removal of copper ions from the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The copper ion removal rate (P value) using the method of this example was 24.60±5.04%.

[0089] Example 7

[0090] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0091] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0092] S2: Add aspartic acid to 0.05 mol / L PBS buffer and adjust the pH to 5.50 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with an aspartic acid concentration of 5 mmol / L.

[0093] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 2 minutes, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0094] S4: Cyclic voltammetry was used to evaluate the removal of copper ions from the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The copper ion removal rate (P value) using the method of this example was 48.45±0.89%.

[0095] Example 8

[0096] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0097] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0098] S2: Add aspartic acid to 0.05 mol / L PBS buffer and adjust the pH to 5.50 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with an aspartic acid concentration of 5 mmol / L.

[0099] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 5 minutes, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0100] S4: Cyclic voltammetry was used to evaluate the removal of copper ions from the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The copper ion removal rate (P value) of the method of this example was 67.77±2.28%.

[0101] Example 9

[0102] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0103] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0104] S2: Add aspartic acid to 0.05 mol / L PBS buffer and adjust the pH to 5.50 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with an aspartic acid concentration of 5 mmol / L.

[0105] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 600 seconds, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0106] S4: Cyclic voltammetry was used to evaluate the removal of copper ions from the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The copper ion removal rate (P value) using the method of this example was measured to be 96.25±0.80%.

[0107] According to the test results in Example 1 and Example 4 to Example 9, a curve showing the relationship between the immersion time of the remover solution and the copper ion removal rate is drawn. The curve obtained by fitting is as follows: Figure 4 As shown, it can be seen that: in a short period of time, the copper ion removal rate increases positively with time, and then increases slowly until it no longer changes significantly with time.

[0108] Example 10

[0109] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0110] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0111] S2: Add glutamic acid to 0.05 mol / L PBS buffer and adjust the pH to 5.50 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with a glutamic acid concentration of 5 mmol / L.

[0112] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 10 minutes, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0113] S4: Cyclic voltammetry was used to evaluate the removal effect of copper ions from the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The obtained cyclic voltammetry diagram is shown in FIG. Figure 5 , it was measured that the copper ion removal rate (P value) using the method of this embodiment was 88.23±0.73%.

[0114] Example 11

[0115] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0116] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0117] S2: Add aspartic acid to 0.05 mol / L PBS buffer and adjust the pH to 5.00 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with an aspartic acid concentration of 5 mmol / L.

[0118] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 10 minutes, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0119] S4: Cyclic voltammetry was used to evaluate the removal of copper ions from the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The copper ion removal rate (P value) using the method of this example was 95.54±0.84%.

[0120] Comparative Example 1

[0121] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0122] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0123] S2: Lysine was added to 0.05 mol / L PBS buffer and the pH value was adjusted to 5.50 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with a lysine concentration of 5 mmol / L.

[0124] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 10 minutes, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0125] S4: Cyclic voltammetry was used to evaluate the removal effect of copper ions from the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The obtained cyclic voltammetry diagram is shown in FIG. Figure 5 , it was measured that the copper ion removal rate (P value) using the method of this comparative example was 66.49±1.05%.

[0126] Comparative Example 2

[0127] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0128] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0129] S2: Phenylalanine was added to 0.05 mol / L PBS buffer and the pH value was adjusted to 5.50 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with a phenylalanine concentration of 5 mmol / L.

[0130] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 10 minutes, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0131] S4: Cyclic voltammetry was used to evaluate the removal effect of copper ions from the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The obtained cyclic voltammetry diagram is shown in FIG. Figure 5 , it was measured that the copper ion removal rate (P value) using the method of this comparative example was 60.94±2.05%.

[0132] According to the test results in Example 1, Example 10, Comparative Example 1 and Comparative Example 2, the comparison of the removal effect of copper ions on the surface of cysteine membrane when different amino acids are used as removers is shown in FIG. Figure 5 and Figure 6 , it can be seen that the copper ion removal effect is aspartic acid > glutamic acid > lysine > phenylalanine. The reason is:

[0133] (1) Lysine carries a positive charge at pH 5.50, and there is a strong electrostatic repulsion between it and the copper ions on the membrane surface. Compared with aspartic acid, lysine has three more methylene groups in its molecular chain, which increases the flexibility of the molecular chain and is not conducive to its binding with the copper ions on the membrane surface. Therefore, the removal effect of copper ions on the membrane surface is poor.

[0134] (2) Phenylalanine has a net charge of approximately zero at pH 5.50, but its molecular structure contains a benzene ring, which produces a steric hindrance effect that hinders its electrostatic interaction with the membrane surface, resulting in a low copper ion removal rate.

[0135] (3) Glutamic acid and aspartic acid both carry negative charges at pH 5.50, which can produce a weak electrostatic repulsion with the cysteine membrane surface with a small amount of negative charge, and form a strong electrostatic attraction and coordination effect with copper ions, thereby achieving the removal of copper ions from the cysteine membrane surface; however, compared with aspartic acid, glutamic acid has an additional methylene group in its molecular chain, which increases the flexibility of the molecular chain and reduces the probability of electrostatic binding between glutamic acid and copper ions on the membrane surface, which is not conducive to the removal of copper ions from the membrane surface.

[0136] Comparative Example 3

[0137] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0138] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0139] S2: Add aspartic acid to 0.05 mol / L PBS buffer and adjust the pH to 4.05 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with an aspartic acid concentration of 5 mmol / L.

[0140] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 10 minutes, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0141] S4: Cyclic voltammetry was used to evaluate the removal of copper ions from the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The copper ion removal rate (P value) using the method of this comparative example was 73.25±1.05%.

[0142] Comparative Example 4

[0143] Follow the steps below to regenerate the copper ion-contaminated amino acid membrane (cysteine membrane) and test the copper ion removal effect on the amino acid membrane surface:

[0144] S1: A gold electrode with a cysteine film assembled on its surface was used as the working electrode. The working electrode was soaked in a 1.0 mmol / L copper sulfate solution for 20 minutes, then taken out and rinsed with deionized water to obtain a working electrode with copper ions enriched on its surface.

[0145] S2: Add aspartic acid to 0.05 mol / L PBS buffer and adjust the pH to 6.50 with hydrochloric acid and sodium hydroxide solution to obtain a remover solution with an aspartic acid concentration of 5 mmol / L.

[0146] S3: Immerse the working electrode with copper ions enriched on its surface in step S1 into the remover solution obtained in step S2. After soaking at room temperature for 10 minutes, take out the working electrode and rinse the surface of the working electrode with deionized water to obtain a working electrode after cysteine membrane regeneration.

[0147] S4: Cyclic voltammetry was used to evaluate the copper ion removal effect on the surface of the cysteine membrane on the working electrode. The specific process was the same as step S5 in Example 1. The copper ion removal rate (P value) using the method of this comparative example was 53.24±0.18%.

[0148] Comparing the test results in Example 1, Example 11, Comparative Example 3, and Comparative Example 4, it can be seen that when the pH value of the remover solution is 5.0-5.5, a good removal effect of copper ions on the surface of the cysteine membrane can be achieved; both too high and too low pH values of the remover solution will result in a decrease in the copper ion removal rate. Analysis shows that when the remover solution is too acidic (the pH value is too low), the positive charge on the surface of the cysteine membrane increases, the electrostatic repulsion between the membrane and the remover (aspartic acid) is weakened, and the electrostatic attraction is enhanced, which is not conducive to the removal of copper ions on the membrane surface. When the remover solution is too alkaline (the pH value is too high), the surface of the cysteine membrane has excessive negative charge, and the electrostatic attraction between the membrane and the copper ions is enhanced, which is also not conducive to the removal of copper ions. In addition, copper ions tend to form precipitation in an overly alkaline environment, and the formation of trace Cu(OH)2 precipitation further aggravates the contamination of the membrane surface.

[0149] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this disclosure pertains. Unless otherwise specified, the raw materials and equipment used herein are conventional in the art and can be obtained from conventional commercial sources. The methods used herein are conventional in the art, unless otherwise specified.

[0150] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for regenerating an amino acid membrane contaminated by copper ions, characterized in that: The following steps are involved: The amino acid membrane contaminated by copper ions is immersed in a remover solution; the amino acid membrane is composed of cysteine; and the remover is aspartic acid; The pH value of the remover solution is 5.0-5.

5.

2. The method for regenerating an amino acid membrane contaminated by copper ions according to claim 1, wherein: The concentration of the remover solution is 5-10 mmol / L.

3. The method for regenerating an amino acid membrane contaminated by copper ions according to claim 1 or 2, wherein: The soaking time is not less than 10 min.

4. The method for regenerating an amino acid membrane contaminated by copper ions according to claim 1 or 2, wherein: The remover solution is prepared from a remover and a phosphate buffer solution; the concentration of the phosphate buffer solution is 0.05-0.1 mol / L.

5. The method for regenerating an amino acid membrane contaminated by copper ions according to claim 1, wherein The amino acid membrane is assembled on the surface of the metal electrode; after the copper ion-contaminated amino acid membrane is immersed in a remover solution, the copper ion removal effect on the amino acid membrane surface is detected by scanning electrochemical microscopy and / or cyclic voltammetry.

6. The method for regenerating an amino acid membrane contaminated by copper ions according to claim 5, wherein: The steps of the cyclic voltammetry method include: using a metal electrode with an amino acid film on its surface as a working electrode, assembling it together with a counter electrode, a reference electrode and an electrolyte to form an electrochemical device, performing a forward scan, integrating the copper ion reduction peak to obtain the reduction peak charge, and calculating the decrease rate of the reduction peak charge after the amino acid film contaminated with copper ions is immersed in a remover solution compared to before immersion to obtain the copper ion removal rate.

7. The method for regenerating an amino acid membrane contaminated by copper ions according to claim 5 or 6, wherein: The metal electrode is a gold electrode.

8. The method for regenerating an amino acid membrane contaminated by copper ions according to claim 6, wherein: The counter electrode is a platinum wire; the reference electrode is an Ag / AgCl electrode; the electrolyte is a phosphate buffer solution containing KCl and K4Fe(CN)6; during the forward scan, the electrochemical window is -0.2~0.6 V, and the scan rate is 0.05~0.1 V / s.

9. The method for regenerating an amino acid membrane contaminated by copper ions according to claim 8, wherein: The pH value of the electrolyte is 5.0-5.5, the content of KCl is 0.1-0.2 mol / L, and the content of K4Fe(CN)6 is 0.5-2.0 mmol / L.

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