A method for electrochemical detection of phenolic amine pollutants based on DOTP

Abstract

The application specifically discloses a phenolic amine pollutant electrochemical detection method based on DOTP. The method constructs a double-cell primary battery system; adds a persulfate oxidant in the positive electrode chamber and sets a positive electrode; adds a to-be-detected liquid containing phenolic or amine pollutants in the negative electrode chamber and sets a negative electrode; connects the positive electrode and the negative electrode through an external circuit to form a closed loop, drives electron transfer by using the chemical potential difference inside the system, and generates a spontaneous current; records the change curve of the current with time, extracts the current value in the stable stage; further prepares a plurality of standard solutions with known pollutant concentrations, establishes a linear regression equation of the current in the stable stage and the pollutant concentration; and substitutes the current value in the stable stage of the water sample to be detected into the equation to calculate the pollutant concentration. The application can realize self-powered detection without an external power supply, has a fast response speed, is suitable for quantitative analysis of phenols, anilines and derivatives thereof, and can be used for on-site rapid detection of industrial wastewater.

Description

Technical Field

[0001] This application relates to the field of environmental electrochemical detection technology, and in particular to an electrochemical detection method for phenolic amine pollutants based on DOTP. Background Technology

[0002] Phenolic and aniline compounds are important raw materials and intermediates in many chemical industries, including dyes, pharmaceuticals, pesticides, synthetic resins, coking, oil refining, and plastics. These industries generate large amounts of phenol / amine-containing organic wastewater during production. This wastewater is generally characterized by high pollutant concentrations, strong biotoxicity, and poor biodegradability, making it a key target for industrial water pollution control in my country. Rapid and accurate detection of phenol / amine pollutant concentrations is a crucial technical step in the treatment and discharge monitoring of this wastewater, enabling effective pollution source monitoring, treatment process operation evaluation, and environmental risk assessment. Existing methods for detecting phenol / amine pollutants and evaluating wastewater treatment effectiveness mainly fall into the following categories.

[0003] Firstly, there are laboratory analytical methods based on chromatography or spectroscopy. High-performance liquid chromatography (HPLC) has the advantages of good separation and high accuracy, but the equipment is expensive, the operation is complex, and the detection cycle is long, making it impossible to achieve online monitoring of pollution sources and wastewater treatment facilities. Ultraviolet spectrophotometry is relatively simple to operate, but it is easily affected by coexisting matrices in wastewater (such as suspended solids, colored substances, and other ultraviolet-absorbing species), sample pretreatment is cumbersome, and the detection sensitivity is often insufficient to meet the detection requirements of low-concentration pollutants.

[0004] Secondly, there are traditional electrochemical sensors based on external power supplies. This type of method has attracted attention due to its advantages such as fast response speed and relatively low equipment cost. However, most existing electrochemical sensors adopt a three-electrode system and rely on a potentiostat to provide an external driving potential. This not only increases the complexity of the equipment and energy consumption, but also hinders the miniaturization and on-site deployment of the sensors, thus limiting their application in in-situ detection of industrial wastewater.

[0005] Thirdly, self-powered sensors based on microbial metabolic activity. Microbial fuel cell sensors utilize the metabolic activity of electrogenic microorganisms to convert the chemical energy of organic pollutants into electrical energy, reflecting the pollutant concentration through the output electrical signal. However, this type of sensor is heavily dependent on the growth state and activity of the microorganisms, with system start-up times ranging from several hours to several days, slow response speed, and microbial activity easily affected by wastewater pH, temperature, salinity, and toxic substances, resulting in poor signal stability and making it difficult to meet the needs of frequent and rapid detection in industrial scenarios.

[0006] Fourth, traditional advanced oxidation process characterization methods used for evaluating wastewater treatment effectiveness. In wastewater treatment process monitoring, evaluating the effectiveness of advanced oxidation treatment typically requires the use of a total organic carbon analyzer or chemical oxygen demand (COD) meter to obtain organic matter removal rate data through laboratory analysis of treated water samples. This process is cumbersome, lacks timeliness, and only reflects the final result of mineralization. It cannot output electrical signals in real time during the treatment process, nor can it provide dynamic distribution information of phenol / amine pollutants in the two competing reaction pathways of polymerization and mineralization.

[0007] In summary, existing technologies lack a detection method that can simultaneously reflect the concentration of pollutants and their reaction pathways (mineralization or polymerization tendency) within the system. Therefore, there is an urgent need in the field to develop a detection method for phenol / amine pollutants that requires no external power source, responds rapidly, and can provide real-time feedback on pollutant concentration and reactivity. Summary of the Invention

[0008] To address the problems in the prior art, this application provides an electrochemical detection method for phenolic amine pollutants based on DOTP.

[0009] Firstly, this application provides an electrochemical detection method for phenolic amine pollutants based on DOTP, employing the following technical solution: An electrochemical detection method for phenolic amine pollutants based on DOTP includes the following steps: S1, Construct a dual-cell galvanic cell system, wherein the dual-cell galvanic cell system includes a positive electrode chamber, a negative electrode chamber, and a cation exchange membrane; S2, an electrolyte solution and a buffer salt are added to the positive electrode chamber and the negative electrode chamber, respectively; An oxidant is added to the positive electrode chamber, and a positive electrode is provided. The test solution containing contaminants is added to the negative electrode chamber, and a negative electrode is set thereup. S3, the positive electrode and the negative electrode are connected through an external circuit to form a closed loop system; Record the curve of spontaneous current generated by the closed loop system over time to obtain the current value in the steady-state stage after the addition of the test liquid; S4. Prepare multiple standard solutions with known pollutant concentrations respectively. Use the standard solutions as the test solutions and repeat steps S2-S3 to obtain the current value of the stable stage corresponding to each standard solution. A standard curve was plotted with the current value during the stable phase as the ordinate and the corresponding pollutant concentration in the standard solution as the abscissa, and a linear regression equation was obtained by fitting the curve. S5. For a water sample with an unknown pollutant concentration, use the water sample as the test liquid and repeat steps S2-S3 to obtain the corresponding stable stage current value. Substitute the value into the linear regression equation obtained in S4 to calculate the pollutant concentration in the water sample.

[0010] In this application, DOTP is short for Direct Oxidative Transfer Process. In S1, the cation exchange membrane physically isolates the positive and negative electrode chambers, preventing the oxidant from directly contacting the pollutants and causing a homogeneous reaction, while allowing cations to pass through to maintain the charge balance between the two chambers. In S2, the positive electrode is used to activate the persulfate oxidant, making it an electron acceptor, while the negative electrode is used to adsorb and activate phenolic amine pollutants, causing them to release electrons. In S3, after the positive and negative electrodes are connected by an external circuit, the electrons released from the pollutant side spontaneously migrate to the oxidant side through the external circuit, forming a current signal in a closed loop. In S4, a linear regression equation Y=aX+b is established between current and concentration using multiple standard solutions of known concentrations. In S5, the concentration of pollutants in the water sample can be calculated by substituting the current value of the steady-state stage corresponding to the water sample into this equation.

[0011] In this application's technical solution, the generation of the current signal relies entirely on the chemical potential difference within the system driving electron transfer, achieving self-powered operation without the need for an external power source. Simultaneously, the current signal reaches a stable plateau within minutes of the addition of the test solution. Based on the linear regression equation established between the current value during this stable plateau and the pollutant concentration, accurate quantification of the pollutants can be achieved. Furthermore, since the detection current originates from the DOTP two-electron transfer and coupling polymerization reaction of phenolic / amine pollutants on the CuO electrode surface, and aromatic compounds containing electron-withdrawing groups (such as benzoic acid) lack this reactivity, this method exhibits selective response to phenolic / amine pollutants with DOTP polymerization activity. The combination of self-powered operation, rapid response, quantitative detection, and selective identification enables this method to meet the application requirements for rapid on-site detection of industrial wastewater.

[0012] Preferably, the contaminant includes at least one of phenols, anilines, or their derivatives.

[0013] This application defines the types of pollutants: phenols, anilines, and their derivatives all contain active functional groups such as phenolic hydroxyl or amino groups, which can be adsorbed and undergo two-electron transfer on the CuO electrode surface, thereby triggering the DOTP process and generating a current signal. This definition clarifies the scope of detection applicable to this method and indicates its versatility for phenolic amine pollutants with different structures.

[0014] Preferably, the oxidant includes at least one of sodium persulfate and potassium persulfate.

[0015] Sodium persulfate is the preferred oxidant in this invention. After being activated on the surface of the CNT electrode, it has a strong electron-accepting ability and can effectively accept electrons from the contaminant side, providing sufficient driving force for the DOTP process.

[0016] Preferably, the concentration of the oxidant is 10-40 times the molar concentration of the pollutant in the known concentration of the pollutant standard solution.

[0017] Within the aforementioned ratio range, the number of electron acceptors on the oxidant side is sufficient to match the electrons transferred from the external circuit by pollutants of different concentrations. This ensures that the magnitude of the detection current is primarily determined by the electron release rate on the pollutant side, thereby guaranteeing the linear range and slope stability of the standard curve. If the oxidant concentration is too low, the current signal corresponding to high-concentration pollutants will be suppressed due to insufficient electron acceptors, causing the standard curve to exhibit nonlinear bending in the high-concentration region. If the oxidant concentration is too high, although it will not significantly suppress the detection signal, it will result in reagent waste and a slight increase in background current. Controlling the oxidant concentration within the aforementioned multiple range ensures both quantitative linearity and reagent economy.

[0018] Preferably, the buffer salt includes at least one of a boric acid / sodium borate buffer system and a sodium dihydrogen phosphate / disodium hydrogen phosphate buffer system; after the buffer salt is added in S2, the pH value of the reaction system in the positive electrode chamber is 5.8-7.

[0019] This application further specifies the buffer salt as a boric acid / sodium borate buffer system and controls the pH value of the positive electrode reaction system within the aforementioned range. The boric acid / sodium borate buffer system exhibits good buffering capacity within this pH range, effectively resisting local pH fluctuations that may occur during persulfate activation, thus maintaining a stable reaction environment in the positive electrode chamber. This pH range is beneficial for maintaining the chemical stability of the oxidant, preventing its non-target decomposition, and also matches the suitable ionization state of phenolic amine pollutants, facilitating their adsorption and two-electron transfer on the negative electrode surface. Simultaneously, the components of the boric acid / sodium borate buffer salt do not participate in the redox reaction during the DOTP process and will not interfere with the electrode interface reaction, thereby ensuring that the current signal accurately reflects the pollutant concentration and improving the accuracy and reproducibility of the detection results.

[0020] Preferably, the positive electrode comprises a carbon nanotube-supported electrode, wherein the loading of the carbon nanotubes is 1.0-1.5 mg / cm³. 2 .

[0021] Carbon nanotubes possess excellent electrical conductivity and a large specific surface area, providing ample active sites for the interfacial activation of persulfate. Furthermore, their unique electronic structure facilitates electron transfer between the oxidant and the electrode. By controlling the carbon nanotube loading within the aforementioned range, sufficient active sites are ensured at the positive electrode to activate persulfate, while avoiding the increased internal resistance and mass transfer resistance caused by an excessively thick catalyst layer due to excessive loading. This results in a highly efficient and smooth electron acceptance process on the positive electrode side.

[0022] Preferably, the negative electrode comprises a CuO-supported electrode or a modified electrode thereof, wherein the loading of the active component in the CuO or the modified electrode is 1.5-2.0 mg / cm³. 2 .

[0023] CuO, as a transition metal oxide, possesses abundant active sites on its surface, enabling it to effectively adsorb phenolic amine pollutant molecules through coordination and catalyze the formation of free radical intermediates through two-electron transfer at the electrode interface. Controlling the loading of the active component within the aforementioned range ensures sufficient active sites on the negative electrode surface to match the adsorption and activation requirements of different pollutant concentrations. Simultaneously, it avoids the decrease in catalytic efficiency caused by the aggregation of active components when the loading is too high, ensuring a good linear response between the electron release rate and pollutant concentration during the DOTP process.

[0024] Preferably, the load substrate for the positive electrode and the negative electrode includes at least one of carbon paper and titanium mesh.

[0025] Both carbon paper and titanium mesh have good electrical conductivity and corrosion resistance. As a support substrate, they can provide stable mechanical support and efficient electronic transport channels for the catalyst. At the same time, their porous or mesh structure is conducive to the diffusion and mass transfer of reactants on the electrode surface, thereby improving the sensitivity and speed of detection response.

[0026] Preferably, the electrolyte in the electrolyte solution includes sodium sulfate, and the concentration of the electrolyte solution is 10-100 mmol / L.

[0027] Sodium sulfate is an inert supporting electrolyte that, within this concentration range, can effectively reduce the internal resistance of the two-cell system and increase the ion migration rate of the solution, thereby reducing the influence of ohmic polarization on the current signal. Simultaneously, sodium sulfate does not undergo side reactions with other components in the system within this concentration range, nor does it significantly interfere with the adsorption and electron transfer in the DOTP process, ensuring that the measured steady-state current accurately reflects the pollutant concentration.

[0028] Preferably, the steady-state current is the current value corresponding to the current response entering the steady plateau period after the closed loop is formed; the steady plateau period occurs within a time period of 2-10 minutes after the closed loop is formed.

[0029] When the adsorption activation and electron transfer rate of pollutants on the negative electrode surface reaches a dynamic equilibrium with the electron acceptance rate of the oxidant on the positive electrode, the current in the external circuit enters a stable plateau period. The current value during this plateau period exhibits good reproducibility and concentration dependence, making it an ideal signal for establishing quantitative relationships. The 2-10 minute time window indicates that this method has a fast response speed, capable of completing a detection within minutes, meeting the application requirements for rapid on-site detection.

[0030] Secondly, this application provides a method for regenerating the negative electrode in the method described above, employing the following technical solution: A method for regenerating a negative electrode in the method described above includes the following steps: annealing the deactivated negative electrode at 350-400°C for 2-3 hours.

[0031] Preferably, the criterion for determining the completion of activation of the negative electrode is: when I re When the current value in the stable phase after regeneration recovers to 95%-105% of I0 (the initial stable phase current value), the electrode is considered to be fully activated. It should be noted that the annealing regeneration process can convert a small amount of low-valent copper in the CuO loaded on the surface of the negative electrode into divalent copper, thereby increasing the number of catalytic active sites. Therefore, the current value after regeneration may increase to some extent, but it will still fall within the above-mentioned acceptable recovery range.

[0032] During DOTP detection, phenolic amine contaminants undergo two-electron transfer on the negative electrode surface, forming free radical intermediates. These intermediates further undergo oxidative coupling and polymerization reactions, generating insoluble polymers that accumulate on the CuO electrode surface. With increasing detection cycles, the polymer layer gradually thickens, covering active sites and hindering the diffusion of contaminant molecules to the electrode surface, leading to a decrease in current response. Annealing the deactivated negative electrode at high temperature allows the polymer on the electrode surface to oxidize and decompose, thereby re-exposing the CuO active sites, restoring the electrode's catalytic activity and current response, enabling electrode regeneration and reuse, extending electrode lifespan, and reducing detection costs. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the dual-cell DOTP detection system in various embodiments of this application.

[0034] Figure 2 The linear correlation coefficient R between different experimental parameters and the current-pollutant concentration standard curve during the steady-state phase in Example 1 of this application is given by... 2The effect heatmap shows that Figure (A) represents the effect of oxidant concentration on the molar ratio of phenol (2, 5, 10, and 20 times) on R. 2 The effect of electrolyte solution concentrations (5 mmol / L, 10 mmol / L, 50 mmol / L, 100 mmol / L) on R; Figure (B) shows the effect of electrolyte solution concentrations (5 mmol / L, 10 mmol / L, 50 mmol / L, 100 mmol / L) on R. 2 The effect of pH (5.8, 6.2, 6.7, 7.0) on R; Figure (C) shows the effect of pH (5.8, 6.2, 6.7, 7.0) on R. 2 The effect; Figure (D) shows the loading of carbon nanotubes in the positive electrode (0.5 mg / cm³). 2 1.5 mg / cm 2 2.0 mg / cm 2 ) for R 2 The effect; Figure (E) shows the CuO loading on the negative electrode (1.5 mg / cm³). 2 2.0 mg / cm 2 4.0 mg / cm 2 ) for R 2 The impact.

[0035] Figure 3 Figure 1 shows the detection results of the independently prepared phenol standard solution in Example 2 of this application; Figure 2(A) shows the steady-state current-time response curves of phenol at different concentrations of 1, 2, 5 and 10 mg / L; Figure 3(B) shows the linear relationship between steady-state current and phenol concentration.

[0036] Figure 4 This is a graph showing the detection results of phenol under the segmented spiking method in Example 3 of this application; wherein, Figure 4 (A) shows the current-time response curves during the steady-state phase, with phenol concentrations corresponding to each step being 1 mg / L, 2 mg / L, 4 mg / L, 6 mg / L, and 8 mg / L, respectively. Figure 4 (B) is a graph showing the linear relationship between current and phenol concentration during the steady-state phase.

[0037] Figure 5 This is a comparison of the current-time response curves before and after electrode annealing and regeneration in Example 4 of this application.

[0038] Figure 6 Figure 5 shows the detection results of the aniline standard solution prepared independently in Example 5 of this application; Figure (A) shows the steady-state current-time response curves of aniline at different concentrations, with aniline concentrations of 1 mg / L, 2 mg / L, 5 mg / L, and 10 mg / L, respectively; Figure (B) shows the linear relationship between steady-state current and aniline concentration.

[0039] Figure 7 This is a schematic diagram illustrating the effect of adding benzoic acid on the current-time response curve of phenol wastewater in Example 6 of this application. Detailed Implementation

[0040] To better understand and implement this application, the technical solution will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some of the embodiments of this application, and not all of them.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0042] Unless otherwise stated, all numerical values ​​for the amounts of expressed components, reaction conditions, etc., used in the specification and claims are to be understood as being modified by the term "about". Therefore, unless otherwise indicated, the numerical parameters set forth herein are approximate values ​​that can be varied to obtain the desired performance.

[0043] The word “and / or” as used in this article refers to one or all of the elements mentioned.

[0044] The terms "include" and "contain" as used in this article cover both cases where only the mentioned elements exist and cases where other unmentioned elements exist in addition to the mentioned elements.

[0045] All percentages in this application are weight percentages unless otherwise stated.

[0046] Unless otherwise stated, the terms “a,” “an,” “an,” and “the” as used in this specification are intended to include “at least one” or “one or more.” For example, “a component” refers to one or more components, and therefore more than one component may be considered and may be employed or used in the implementation of the described embodiments.

[0047] Example 1: Optimization of Detection Condition Parameters S1 employs an H-type dual-cell reactor, with a cation exchange membrane (CEM) separating the reactor into a positive electrode chamber and a negative electrode chamber; S2, an electrolyte solution (100 mmol / L sodium sulfate) was added to the positive electrode chamber. An oxidant (10 mmol / L sodium persulfate Na₂S₂O₈) and a buffer salt (20 mmol / L phosphate buffer, adjusting the pH to 7.5) were also added to the positive electrode chamber. A positive electrode (a carbon nanotube-loaded electrode based on a titanium mesh, with a carbon nanotube loading of 1.5 mg / cm²) was then set up. 2 ); Phenol samples (initial phenol concentrations of 1 mg / L, 2 mg / L, 5 mg / L, and 10 mg / L) were added to the negative electrode chamber. Simultaneously, electrolyte solution (100 mmol / L sodium sulfate) and buffer salt (20 mmol / L phosphate buffer, adjusted to pH 7.5) were added to the negative electrode chamber. A negative electrode (a CuO-loaded electrode based on a titanium mesh, with a CuO loading of 2.0 mg / cm²) was then set up. 2 ); S3 connects the positive electrode and the negative electrode through an external circuit to form a closed loop system. The current of the system is monitored using an electrochemical workstation, and the curve of the spontaneous current generated by the closed loop system over time is recorded to obtain the current value of the steady stage after the addition of each concentration of the test sample. S4. Plot a standard curve with phenol concentration on the x-axis and steady-state current value on the y-axis, fit the curve to obtain a linear regression equation, and calculate the linear correlation coefficient R. 2 .

[0048] Based on the standard procedure (S1-S4) described above, keeping other conditions constant, the following parameters are changed respectively, and the linear correlation coefficient R of each parameter on the standard curve is examined. 2 Impact: (1) Oxidizing agent concentration: The concentration of sodium persulfate was set to 2, 5, 10 and 20 times the molar concentration of phenol, respectively; (2) Electrolyte solution concentration: The sodium sulfate concentration was set to 5 mmol / L, 10 mmol / L, 50 mmol / L and 100 mmol / L respectively; (3) pH: The pH of the system was set to 5.8, 6.2, 6.7 and 7.0 respectively; (4) CNT loading at the positive electrode: The CNT loading was set to 0.5 mg / cm³. 2 1.5 mg / cm 2 2.0 mg / cm 2 ; (5) CuO loading at the negative electrode: The CuO loading was set to 1.5 mg / cm³. 2 2.0 mg / cm 2 4.0 mg / cm 2 .

[0049] In the embodiments of this application, the linear correlation coefficient R between different parameters and the standard curve of current-pollutant concentration in the steady-state phase is... 2 The effects are as follows Figure 2 As shown.

[0050] Example 2: Quantitative Detection of Phenol Standard Solution Prepared Independently S1 employs an H-type dual-cell reactor, with a cation exchange membrane (CEM) separating the reactor into a positive electrode chamber and a negative electrode chamber; S2, an electrolyte solution (100 mmol / L sodium sulfate) was added to the positive electrode chamber. An oxidant (10 mmol / L sodium persulfate Na₂S₂O₈) and a buffer salt (20 mmol / L phosphate buffer, adjusting the pH to 7.5) were also added to the positive electrode chamber. A positive electrode (a carbon nanotube-loaded electrode based on a titanium mesh, with a carbon nanotube loading of 1.5 mg / cm²) was then set up. 2 ); The test solution containing phenol (initial phenol concentration 1 mg / L) was added to the negative electrode chamber. Simultaneously, an electrolyte solution (100 mmol / L sodium sulfate) and a buffer salt (20 mmol / L phosphate buffer, adjusted to pH 7.5) were added to the negative electrode chamber. A negative electrode (a CuO-loaded electrode with a titanium mesh substrate, CuO loading of 2.0 mg / cm²) was then set up. 2 ); S3 connects the positive and negative electrodes through an external circuit to form a closed-loop system, and uses an electrochemical workstation to monitor the current of the system. Record the curve of spontaneous current generated by the closed loop system over time to obtain the current value in the steady-state stage after the addition of the test liquid; S4. Prepare standard solutions with phenol concentrations of 1 mg / L, 2 mg / L, 5 mg / L, and 10 mg / L respectively. Repeat steps S2-S3 to obtain the current values ​​of the steady-state phase for each standard solution. A standard curve was plotted with the steady-state current value on the ordinate and the concentration of phenol in the corresponding standard solution on the abscissa. The fitted linear regression equation was Y = 16.7X - 5.65, R0. 2 It is 0.99; S5. For a water sample with an unknown pollutant concentration, repeat steps S2-S3 to obtain its corresponding steady-state current value, substitute it into the linear regression equation obtained in step S4, and calculate the concentration of pollutants in the water sample.

[0051] The detection results of the independently prepared phenol standard solution in this embodiment are shown in the figure below. Figure 3 As shown.

[0052] Example 3 Quantitative Detection of Phenol Using Segmented Spiking Method S1 employs an H-type dual-cell reactor, with a cation exchange membrane (CEM) separating the reactor into a positive electrode chamber and a negative electrode chamber; S2, an electrolyte solution (100 mmol / L sodium sulfate) was added to the positive electrode chamber. An oxidant (10 mmol / L sodium persulfate Na₂S₂O₈) and a buffer salt (20 mmol / L phosphate buffer, adjusting the pH to 7.5) were also added to the positive electrode chamber. A positive electrode (a carbon nanotube-supported electrode based on a titanium mesh, with a carbon nanotube loading of 1.0 mg / cm²) was then set up. 2 ); The test solution containing phenol (initial phenol concentration 1 mg / L) was added to the negative electrode chamber. Simultaneously, an electrolyte solution (100 mmol / L sodium sulfate) and a buffer salt (20 mmol / L phosphate buffer, adjusted to pH 7.5) were added to the negative electrode chamber. A negative electrode (a CuO-loaded electrode with a titanium mesh substrate, CuO loading of 2.0 mg / cm²) was then set up. 2 ); S3 connects the positive and negative electrodes through an external circuit to form a closed-loop system, and uses an electrochemical workstation to monitor the current of the system. Record the curve of spontaneous current generated by the closed loop system over time to obtain the current value in the steady-state stage after the addition of the test liquid; S4. Phenol reagent was added multiple times using a segmented spiking method to make the phenol concentration in the system 2 mg / L, 4 mg / L, 6 mg / L and 8 mg / L respectively. Steps S2-S3 were repeated to obtain the current value of the steady stage corresponding to each standard solution. A standard curve was plotted with the steady-state current value on the ordinate and the corresponding phenol concentration in the system on the abscissa. The fitted linear regression equation was Y = 6.17X - 6.70, R0. 2 It is 0.99; S5. For a water sample with an unknown pollutant concentration, repeat steps S2-S3 to obtain its corresponding steady-state current value, substitute it into the linear regression equation obtained in step S4, and calculate the concentration of pollutants in the water sample.

[0053] The detection results of phenol under the segmented spiking method in this embodiment are as follows: Figure 4 As shown.

[0054] Example 4: Regeneration and Reuse of the Negative Electrode Using the same H-type two-cell reaction system and detection conditions as in Example 1, and with 10 mg / L phenol standard solution as the detection object, the current value of the negative electrode in the stable stage at the beginning of use (denoted as I0) was recorded.

[0055] Multiple tests were performed consecutively according to the detection method in Example 1. After each test, the negative electrode was removed, rinsed with deionized water, dried, and then reassembled for the next test. The steady-state current value I of the nth test was recorded.n As the number of detections increases, the current value in the steady-state phase gradually decreases, when I... n When the value of I0 drops below 80%, the electrode is considered to be deactivated.

[0056] The deactivated negative electrode was placed in a muffle furnace and annealed at 400°C for 3 hours. After naturally cooling to room temperature, it was removed. The regenerated negative electrode was reassembled into the detection system, and its steady-state current value was measured again using a 10 mg / L phenol standard solution as the detection target, following the detection method in Example 1.

[0057] The results showed that after annealing and regeneration at 400℃, the current value in the stable stage recovered to 97% of the initial value. These results indicate that the negative electrode of this method can be regenerated through annealing.

[0058] The comparison of the steady-state current-time response curves of the electrode after annealing and regeneration at 400℃ and the electrode before reaction (original electrode) in this embodiment is shown in the figure below. Figure 5 As shown.

[0059] Example 5: Quantitative Detection of Aniline Standard Solution by Independent Preparation Method S1 employs an H-type dual-cell reactor, with a cation exchange membrane (CEM) separating the reactor into a positive electrode chamber and a negative electrode chamber; S2, an electrolyte solution (100 mmol / L sodium sulfate) was added to the positive electrode chamber. An oxidant (10 mmol / L sodium persulfate Na₂S₂O₈) and a buffer salt (20 mmol / L phosphate buffer, adjusting the pH to 7.5) were also added to the positive electrode chamber. A positive electrode (a carbon nanotube-loaded electrode based on a titanium mesh, with a carbon nanotube loading of 1.5 mg / cm²) was then set up. 2 ); The test solution containing aniline (initial aniline concentration 1 mg / L) was added to the negative electrode chamber. Simultaneously, an electrolyte solution (100 mmol / L sodium sulfate) and a buffer salt (20 mmol / L phosphate buffer, adjusted to pH 7.5) were added to the negative electrode chamber. A negative electrode (a CuO-loaded electrode with a titanium mesh substrate, CuO loading of 2.0 mg / cm²) was then set up. 2 ); S3 connects the positive and negative electrodes through an external circuit to form a closed-loop system, and uses an electrochemical workstation to monitor the current of the system. Record the curve of spontaneous current generated by the closed loop system over time to obtain the steady-state current value after 5 minutes of adding the test liquid; S4. Prepare standard solutions with aniline concentrations of 1 mg / L, 2 mg / L, 5 mg / L, and 10 mg / L respectively. Repeat steps S2-S3 to obtain the current values ​​of the steady-state phase for each standard solution. A standard curve was plotted with the steady-state current value on the ordinate and the concentration of aniline in the corresponding standard solution on the abscissa. The fitted linear regression equation was Y = 11.3X - 7.74, R0. 2 It is 0.96; S5. For a water sample with an unknown pollutant concentration, repeat steps S2-S3 to obtain its corresponding steady-state current value, substitute it into the linear regression equation obtained in step S4, and calculate the concentration of pollutants in the water sample.

[0060] The detection results of the independently prepared aniline standard solution in this embodiment are shown in the figure below. Figure 6 As shown.

[0061] Example 6: Selectivity Validation Experiment of the Detection Method S1 employs an H-type dual-cell reactor, with a cation exchange membrane (CEM) separating the reactor into a positive electrode chamber and a negative electrode chamber; S2, an electrolyte solution (100 mmol / L sodium sulfate) was added to the positive electrode chamber. An oxidant (10 mmol / L sodium persulfate Na₂S₂O₈) and a buffer salt (20 mmol / L phosphate buffer, adjusting the pH to 7.5) were also added to the positive electrode chamber. A positive electrode (a carbon nanotube-loaded electrode based on a titanium mesh, with a carbon nanotube loading of 1.5 mg / cm²) was then set up. 2 ); The test solution containing phenol (initial phenol concentration 1 mg / L) was added to the negative electrode chamber. Simultaneously, an electrolyte solution (100 mmol / L sodium sulfate) and a buffer salt (20 mmol / L phosphate buffer, adjusted to pH 7.5) were added to the negative electrode chamber. A negative electrode (a CuO-loaded electrode with a titanium mesh substrate, CuO loading of 2.0 mg / cm²) was then set up. 2 ); S3, the positive electrode and the negative electrode are connected by an external circuit to form a closed loop system. The current of the system is monitored by an electrochemical workstation, and the change curve of the spontaneous current generated by the closed loop system over time is recorded. After the current enters the stable plateau period (6 min after reaction), solid benzoic acid is added to the negative electrode chamber and stirred rapidly to completely dissolve it, so that the final concentration of benzoic acid in the system reaches 25 mg / L. The current change is recorded again. The results showed that after the addition of benzoic acid, the current in the system hardly fluctuated and remained at the original stable plateau level. These results indicate that benzoic acid, being neither a phenolic nor an amine compound, cannot undergo adsorption activation and two-electron transfer reactions on the CuO electrode surface, and therefore does not generate interfering current signals. Combined with the experimental results showing that phenol can generate a significant current response in this system, this indicates that the current response of this detection method exhibits DOTP polymerization selectivity. The phenolic hydroxyl (-OH) or amino (-NH2) groups contained in phenolic and aniline compounds are electron-donating groups, endowing them with electron-donating properties, enabling them to undergo two-electron transfer on the CuO electrode surface and initiate DOTP polymerization, thereby generating a current signal. Aromatic compounds containing electron-withdrawing groups such as carboxyl groups (-COOH) do not possess the above-mentioned reactivity and do not generate a current response. This detection method has a specific response to phenolic / amine target pollutants with DOTP polymerization activity, and non-target coexisting substances do not significantly interfere with the detection signal.

[0062] In this embodiment, the effect of adding benzoic acid on the current-time response curve of phenol wastewater is as follows: Figure 7 As shown.

[0063] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application, but such modifications or substitutions are all within the scope of protection of this application.

Claims

1. An electrochemical detection method for phenolic amine pollutants based on DOTP, characterized in that: Includes the following steps: S1, Construct a dual-cell galvanic cell system, wherein the dual-cell galvanic cell system includes a positive electrode chamber, a negative electrode chamber, and a cation exchange membrane; S2, an electrolyte solution and a buffer salt are added to the positive electrode chamber and the negative electrode chamber, respectively; An oxidant is added to the positive electrode chamber, and a positive electrode is provided. The test solution containing contaminants is added to the negative electrode chamber, and a negative electrode is set thereup. S3, the positive electrode and the negative electrode are connected through an external circuit to form a closed loop system; Record the curve of spontaneous current generated by the closed loop system over time to obtain the current value in the steady-state stage after the addition of the test liquid; S4. Prepare multiple standard solutions with known pollutant concentrations respectively. Use the standard solutions as the test solutions and repeat steps S2-S3 to obtain the current value of the stable stage corresponding to each standard solution. A standard curve was plotted with the current value during the stable phase as the ordinate and the corresponding pollutant concentration in the standard solution as the abscissa, and a linear regression equation was obtained by fitting the curve. S5. For a water sample with an unknown pollutant concentration, use the water sample as the test liquid and repeat steps S2-S3 to obtain the corresponding stable stage current value. Substitute the value into the linear regression equation obtained in S4 to calculate the pollutant concentration in the water sample.

2. The electrochemical detection method for phenolic amine pollutants based on DOTP as described in claim 1, characterized in that: The contaminants include at least one of phenols, anilines, or their derivatives.

3. The electrochemical detection method for phenolic amine pollutants based on DOTP as described in claim 1, characterized in that: The oxidant includes at least one of sodium persulfate and potassium persulfate.

4. The electrochemical detection method for phenolic amine pollutants based on DOTP according to claim 1, characterized in that: The buffer salt includes at least one of the following: boric acid / sodium borate buffer system and sodium dihydrogen phosphate / disodium hydrogen phosphate buffer system; After the buffer salt is added to S2, the pH value of the reaction system in the positive electrode chamber is 5.8-7.

5. The electrochemical detection method for phenolic amine pollutants based on DOTP as described in claim 1, characterized in that: The positive electrode includes a carbon nanotube-supported electrode, wherein the carbon nanotube loading is 1.0-1.5 mg / cm³. 2 .

6. The DOTP-based electrochemical detection method for phenolic amine pollutants as described in claim 1, characterized in that: The negative electrode comprises a CuO-supported electrode or a modified electrode thereof, wherein the loading of the active component in the CuO or the modified electrode is 1.5-2.0 mg / cm³. 2 .

7. The electrochemical detection method for phenolic amine pollutants based on DOTP as described in claim 1, characterized in that: The load substrate for the positive electrode and the negative electrode includes at least one of carbon paper and titanium mesh.

8. The electrochemical detection method for phenolic amine pollutants based on DOTP as described in claim 1, characterized in that: The electrolyte in the electrolyte solution includes sodium sulfate, and the concentration of the electrolyte solution is 10-100 mmol / L.

9. The DOTP-based electrochemical detection method for phenolic amine pollutants as described in claim 1, characterized in that: The steady-state current is the current value corresponding to the current response entering a stable plateau period after the closed loop is formed. The stable plateau period occurs within 2-10 minutes after the closed loop is formed.

10. A method for regenerating the negative electrode in any one of claims 1-9, characterized in that: The process includes the following steps: annealing the deactivated negative electrode at 350-400℃ for 2-3 hours.

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