Preparation method and application of a chemically modified titanium-based sensor

Abstract

The present invention discloses a preparation method of a chemically modified titanium-based sensor, and the method comprises the following steps: Pretreatment of a titanium electrode: polishing the surface of the titanium electrode until it is smooth and flat, and performing ultrasonic cleaning and drying; Chemical modification of the titanium electrode: first performing nanomaterial modification on the pretreated titanium electrode, and then performing functional molecule modification. The present invention also discloses a chemically modified titanium-based sensor, its application, and a method for detecting titanium content. The chemically modified titanium-based sensor provided by the method of the present invention improves the selective adsorption ability for titanium ions, improves the accuracy and reliability of analysis results, can achieve highly sensitive detection of titanium content and has a wide concentration range.

Description

Technical Field

[0001] The present invention belongs to the field of metal content detection, and particularly relates to a preparation method and application of a chemically modified titanium-based sensor. Background Art

[0002] With the growth of the demand for novel materials and innovative designs in the contemporary jewelry market, titanium jewelry has become an important material in the jewelry manufacturing industry due to its light weight, high strength, and hypoallergenic properties. It has also been increasingly favored by consumers and designers, driving a significant increase in the demand for titanium jewelry. Therefore, developing effective titanium content detection techniques is crucial for ensuring the quality and performance of jewelry. It not only helps consumers identify genuine titanium jewelry but also ensures that manufacturers comply with industry standards and regulatory requirements, and has a positive impact on the optimal use of materials.

[0003] Traditional titanium content detection methods mainly include inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence spectrometry (XRF), and atomic absorption spectrometry (AAS). Although these techniques play an important role in the field of analysis, they usually require expensive equipment, complex sample pretreatment, or are only applicable to detections under specific conditions. For example, although ICP-MS can provide high-sensitivity and accurate analysis results, its high cost and complex operation process limit its application in routine detections. Atomic absorption spectrometry (AAS) has high sensitivity and selectivity for the determination of titanium content, but this method not only requires expensive instruments but also has strict requirements for sample preparation. The sample needs to be digested into a solution state, and the matrix interference in the solution has a great influence on the determination result, and complex matrix correction is required. As a non-destructive analysis technique, XRF can quickly determine the element content in jewelry, but its detection sensitivity for light elements is limited, and the results are easily affected by the surface state of the sample.

[0004] Electrochemical sensors have been widely used in the detection of metal ions due to their advantages such as high sensitivity, good selectivity, and simple operation. By chemically modifying the electrode, the performance of the sensor can be further improved. For the detection of titanium content, developing a suitable chemically modified titanium-based sensor has great potential.

[0005] At present, there have been some research reports on the determination of titanium content by electrochemical methods. For example, some studies have used polarography to determine titanium content. By using the current signal generated by the reduction reaction of titanium ions on the electrode surface in a specific electrolyte system, the titanium content is determined. However, there are still some problems in the existing electrochemical methods for determining titanium content. For example, although the sensitivity of some methods is relatively high, the detection concentration range is relatively narrow, and it cannot meet the wide-range detection requirements of titanium content from low to high in actual samples. Some methods can achieve wide-concentration-range detection to a certain extent, but the sensitivity is not ideal, and the detection limit for low-concentration titanium is relatively high. Summary of the Invention

[0006] One object of the present invention is to provide a method for preparing a titanium-based sensor to solve the above technical problems, and this titanium-based sensor can detect titanium content with high sensitivity and a wide concentration range.

[0007] Another object of the present invention is to provide a titanium-based sensor prepared by the above method.

[0008] Still another object of the present invention is to provide the application of the above titanium-based sensor.

[0009] Yet another object of the present invention is to provide a method for detecting titanium content.

[0010] To achieve the above invention objects, the present invention provides a method for preparing a chemically modified titanium-based sensor, and this method includes the following steps:

[0011] (1) Pretreatment of the titanium electrode: Polish the surface of the titanium electrode until it is smooth and flat, and then perform ultrasonic cleaning and drying.

[0012] (2) Chemical modification of the titanium electrode: First, perform nanomaterial modification on the pretreated titanium electrode obtained in step (1), and then perform functional molecule modification.

[0013] Preferably, the nanomaterial modification includes: Disperse 3 g of graphene oxide in 500 mL of deionized water to prepare a 6 mg / mL graphene oxide dispersion liquid. Add 200 mL of 40% hydroiodic acid aqueous solution for reduction, perform ultrasonic treatment at 60 °C for 5 hours to promote the reaction, centrifuge to obtain a nanographene precipitate, and wash it with ethanol and deionized water, and then dry it. Add 600 mg of nanographene powder to 100 mL of ethanol and ultrasonically disperse it to form a 6 mg / mL nanographene dispersion liquid. Immerse the pretreated titanium electrode completely in the nanographene dispersion liquid for 12 - 24 hours, then take out the electrode and dry it at 60 - 80 °C for 2 - 4 hours to make the nanographene firmly adhere to the electrode surface, and obtain a titanium / graphene electrode.

[0014] Preferably, the functional molecule modification includes: mixing pyrrole monomer and ethanol at a mass ratio of 1:10 to form a sol, stirring at 60 °C for 2 hours and standing for 48 hours to form a PPy gel, uniformly dropping 500 μL of the PPy gel onto the surface of a clean titanium / graphene electrode, drying at room temperature, and finally performing heat treatment at 80 °C to cure the film.

[0015] On the other hand, the present invention also provides a chemically modified titanium-based sensor obtained by the method of the present invention.

[0016] On the other hand, the present invention also provides the application of the chemically modified titanium-based sensor in detecting titanium content.

[0017] On the other hand, the present invention also provides a method for detecting titanium content, which includes the step of using the chemically modified titanium-based sensor for detection.

[0018] Preferably, the method for detecting titanium content according to the present invention includes the following steps:

[0019] (1) Plotting a working curve: placing a three-electrode system in an electrolytic cell containing standard titanium solutions with different concentrations, adding a supporting electrolyte, a buffer solution, and an organic complexing agent solution, setting potential parameters, starting potential scanning, recording current signals at different potentials, and plotting a working curve based on the current signals and the corresponding titanium ion concentrations to ensure a good linear relationship between the peak current of the current and the titanium ion concentration;

[0020] (2) Sample detection: processing the actual sample into a solution form suitable for detection to ensure that the titanium in the sample exists in ionic form, placing the three-electrode system in the sample solution, performing potential scanning and current signal measurement under the same experimental conditions as when plotting the working curve, and finding the corresponding titanium ion concentration from the working curve based on the measured current signal, thereby realizing the detection of the titanium content in the sample. The three-electrode system includes the chemically modified titanium-based sensor of the present invention as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum wire electrode as the counter electrode.

[0021] In this method, since there is a good linear relationship between the stripping peak current and the titanium ion concentration within a certain range, the corresponding titanium ion concentration can be found through the working curve, and the accurate detection of the titanium content in the sample can be achieved.

[0022] Preferably, in step (1), the potential parameter is selected as -0.2 V as the enrichment potential, and the enrichment time is 2 minutes. The stripping potential scanning range is set from -0.5 V to 0.5 V, and the scanning rate is set at 50 mV / s.

[0023] Preferably, in step (1), the supporting electrolyte is potassium chloride solution, preferably with a concentration of 1.0 mol / L. The buffer solution is HAc-NaAc, preferably with a pH of 4.0. The organic complexing agent solution is 5-Br-PADAP, preferably with a concentration of 4.0 mmol / L.

[0024] The titanium-based electrochemical electrode prepared by the present invention enhances the selective adsorption ability for titanium ions through chemical modification. This modified electrode can more effectively distinguish titanium ions from other possible interfering ions, thereby achieving more accurate titanium detection in complex sample matrices. Combining the use of an organic complexing agent, the method of the present invention can significantly improve the detection sensitivity for titanium ions. The complex formed by the organic complexing agent and titanium ions generates an obvious current response during the electrochemical scanning process, making the detection of low-concentration titanium ions possible. In addition, the method of the present invention can accurately detect the concentration of titanium ions in a wide concentration range (from 10 pM to 100 mM), and is applicable to the detection of samples at different concentration levels. Through specific chemical modification and the selection of an organic complexing agent, the method of the present invention realizes highly selective detection of titanium ions, reduces the interference of other coexisting ions, and improves the accuracy and reliability of the analysis results. Description of the Drawings

[0025] Figure 1 It is the adsorptive stripping voltammogram of chemically modifying a titanium electrode with nanographene or polypyrrole.

[0026] Figure 2 It is the adsorptive stripping voltammogram at different enrichment potentials.

[0027] Figure 3 It is the adsorptive stripping voltammogram at different enrichment times.

[0028] Figure 4 It is the adsorptive stripping voltammogram at different concentrations of titanium solution.

[0029] Figure 5 It is the adsorptive stripping voltammogram at different pH values.

[0030] Figure 6 It is the adsorptive stripping voltammogram at different concentrations of complexing agent.

[0031] Figure 7 It is the adsorptive stripping voltammogram with or without interfering ions. Detailed Embodiments

[0032] The following further illustrates the present invention in conjunction with specific embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0033] Example 1: Preparation Method of Chemically Modified Titanium-Based Sensor

[0034] This embodiment details the preparation process of a titanium-based electrochemical sensor, which uses a chemically modified titanium-based electrode to improve the selective adsorption ability of titanium ions.

[0035] 1. Pretreatment of the titanium electrode

[0036] (1) Material selection and cutting: Select high-purity titanium material (purity ≥ 99.95%) and cut it into titanium electrodes of the required size, with a size of 1 cm × 1 cm.

[0037] (2) Surface polishing: Use sandpaper to polish the surface of the titanium electrode in sequence from low grit to high grit (such as 200 mesh, 400 mesh, 600 mesh, 800 mesh, and 1000 mesh) until the surface is smooth and flat.

[0038] (3) Ultrasonic cleaning: Ultrasonically clean the polished titanium electrode (frequency 40KHz) in ethanol and ultrapure water for 15 - 30 minutes to remove surface impurities and oil, and then dry it in a nitrogen atmosphere for standby.

[0039] 2. Chemical modification of the titanium electrode

[0040] (1) Modification with nanomaterials

[0041] Prepare graphene oxide (GO) by the Hummers method. Disperse 3g of GO in 500mL of deionized water to form a 6mg / mL GO dispersion. Add 200mL of 40% (mass concentration) hydroiodic acid aqueous solution for reduction, and perform ultrasonic treatment (frequency 40KHz) at 60°C for 5 hours to promote the reaction. Centrifuge at 9000rpm for 20 minutes to obtain a nanographene precipitate, and wash it twice with ethanol and deionized water. Put it into a vacuum drying oven, take it out after drying at 60°C for 4 hours. Add 600mg of nanographene powder to 100mL of ethanol and ultrasonically disperse it at 40KHz for 30 minutes to form a 6mg / mL nanographene dispersion. Immerse the pretreated titanium electrode completely in the nanographene dispersion for 12 - 24 hours. Then take out the electrode and dry it in an oven at 60 - 80°C for 2 - 4 hours to make the nanographene firmly adhere to the electrode surface.

[0042] (2) Modification with functional molecules

[0043] Polypyrrole (PPy) is a conductive polymer with good redox properties, which makes it easier for titanium ions to adsorb and complex on the electrode surface, thus achieving selective adsorption of titanium ions. Prepare a polypyrrole film on the titanium electrode by the sol - gel method.

[0044] Mix the pyrrole monomer and ethanol in a mass ratio of 1:10 to form a sol, stir it at 60 °C for 2 hours and let it stand for 48 hours to form a gel. Then, uniformly drop 500 μL of the PPy gel onto the surface of a clean titanium / graphene electrode, air-dry it at room temperature, and finally perform heat treatment at 80 °C to cure the film.

[0045] Example 2: Method for detecting titanium content using a chemically modified titanium-based sensor

[0046] 1. Instrument and reagent preparation

[0047] (1) Instrument

[0048] Set up an electrochemical workstation (Metrohm Autolab, Switzerland) for applying potential and measuring current signals. Prepare a three-electrode system, including the chemically modified titanium-based sensor prepared in Example 1 as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum wire electrode as the counter electrode.

[0049] (2) Reagents

[0050] Supporting electrolyte solution: Select potassium chloride solution as the supporting electrolyte with a concentration of 0.1 - 1.0 mol / L.

[0051] Buffer solution with a pH of 2.0 to 5.0: Prepared from different ratios of HAc-NaAc

[0052] Organic complexing agent: Heterocyclic azo reagents can be selected, such as pyridylazo, thiazolylazo, pyrazolylazo

[0053] (5-Br-PADAP)

[0054] (TAR)

[0055] Standard titanium solution: Prepare a series of standard titanium solutions with different concentrations ranging from 10 pM to 100 mM for drawing a working curve.

[0056] 2. Drawing of the working curve

[0057] (1) Preparation of the electrolytic cell: Place the three-electrode system in an electrolytic cell containing standard titanium solutions with different concentrations, add the electrolyte and the organic complexing agent solution, and electrochemically enrich a series of Ti(IV)-complexes with different concentrations under stirring conditions.

[0058] (2) Potential setting: Set parameters such as the potential scan range and scan rate on the electrochemical workstation. The enrichment potential is preferably -0.2 V, the scan rate is 20 - 100 mV / s (preferably 50 mV / s), and the enrichment time is 2 minutes.

[0059] (3)Potential scanning: Start potential scanning. The stripping potential scanning range is from -0.5 V to 0.5 V. Record the current signals at different potentials. When the potential reaches the value at which the redox reaction of titanium ions occurs, corresponding current peaks will be generated.

[0060] (4)Data recording and analysis: According to the recorded current signals and the corresponding titanium ion concentrations, plot a working curve. In a wide concentration range, the peak current of the current peak shows a good linear relationship with the titanium ion concentration.

[0061] 3. Sample detection

[0062] (1)Sample preparation: Process the actual sample into a solution form suitable for detection to ensure that the titanium in the sample exists in ionic form.

[0063] (2)Potential scanning: Place the three-electrode system in the sample solution and perform potential scanning and current signal measurement under the same experimental conditions as when plotting the working curve.

[0064] (3)Concentration determination: According to the measured current signal, find the corresponding titanium ion concentration from the working curve, so as to realize the detection of the titanium content in the sample.

[0065] Example 3: Influence of chemically modifying the titanium electrode with nanographene or polypyrrole on the stripping peak signal

[0066] The adsorption stripping voltammograms of Ti / GNSs / PPy prepared in Example 1, Ti (titanium electrode without any chemical modification), Ti / GNSs (titanium electrode only modified with GNSs nanomaterial (i.e., omitting the "functional molecule modification" step in Example 1)), and Ti / PPy (titanium electrode only modified with PPy (i.e., omitting the "nanomaterials modification" step in Example 1)) in 100 μM Ti 4+ HAc-NaAc (pH 4.0), 4 mmol / L 5-Br-PADAP mixed electrolyte. As Figure 1 shown, the peak currents of bare Ti (curve a) and Ti / GNSs (curve b) change little. The peak current signal of Ti / PPy (curve c) increases compared with curves a and b, indicating that the polypyrrole film is beneficial to the deposition of Ti 4+ on the electrode surface, thereby improving the stripping signal of the analyte ions. The peak current of Ti / GNSs / PPy (curve d) increases significantly because the deposited polypyrrole film and GNSs have a synergistic effect, effectively increasing the electrode surface area, which is beneficial to the adsorption and complexation of titanium ions on the electrode surface, and thus making the stripping signal of Ti 4+ on Ti / GNSs / PPy increase significantly.

[0067] Example 4: Influence of different enrichment potentials on the stripping peak signal

[0068] In this example, the effect of different enrichment potentials on the stripping peak signal of titanium ions was investigated. The supporting electrolyte used in the experiment was potassium chloride solution with a concentration range of 1.0 mol / L. At the same time, 4 mmol / L of 5-Br-PADAP was selected as the organic complexing agent, and an HAc-NaAc buffer solution with pH = 4.0. In a solution containing 100 μM of titanium ions, based on the above conditions, the effect of different enrichment potentials between -0.5 V and 0.5 V on the reduction peak current of titanium ions was explored.

[0069] Figure 2 As shown, as the enrichment potential increased from -0.5 V to 0.5 V, the reduction peak current gradually increased and reached the maximum value at -0.2 V. When the potential was further increased to -0.1 V, the reduction peak current began to decrease. This indicates that the enrichment potential has a significant effect on the electrochemical response signal of titanium ions. Therefore, the enrichment potential was set to -0.2 V to optimize the detection sensitivity of titanium ions. This finding is consistent with the basic principle of electrochemical enrichment, that is, an appropriate enrichment potential can effectively increase the concentration of the target substance on the electrode surface, thereby enhancing the current response.

[0070] Example 5: Effect of Different Enrichment Times on the Stripping Peak Signal

[0071] In this example, the effect of the enrichment time on the reduction peak current of titanium ions was investigated, and the results are shown in Figure 3 . The detection conditions of this example were based on those of Example 4. The results showed that within the enrichment time range of 0 to 5 minutes, as the cumulative time increased from 0 to 2 minutes, the reduction peak current of titanium ions increased significantly, indicating that the titanium ions enriched on the electrode surface gradually increased. As the enrichment time increased from 2 minutes to 5 minutes, the reduction peak current increased very slowly, which may indicate that the enrichment time of 2 minutes had reached the maximum detection amount that the effective detection area of the electrode could load. Considering both sensitivity and analysis time, the enrichment time was set to 2 minutes.

[0072] Example 6: Effect of Different Concentrations of Titanium Solution on the Stripping Peak Signal

[0073] In this example, the ability of the chemically modified titanium-based sensor to detect titanium ions at different concentrations was investigated. Figure 4 In A, for the titanium-based sensor prepared in Example 1 in titanium ion solutions with medium concentrations (30 μM, 50 μM, 100 μM, 120 μM, 160 μM, 220 μM, 320 μM), the current signal increased with the increase in the metal ion concentration, and Figure 4 in B at low concentrations (10 pM, 20 pM, 40 pM, 80 pM, 100 pM, 120 pM, 150 pM) and Figure 4C also has a good linear relationship at high concentrations (1 mM, 2 mM, 4 mM, 8 mM, 10 mM, 12 mM, 16 mM), indicating that the titanium-based electrochemical sensor has good ability to detect titanium ions in one step and performs well in both high and low concentration ranges.

[0074] Example 7: Effect of pH of different buffers on the stripping peak signal

[0075] This example examines the effect of the pH of the buffer on the reduction peak current of titanium ions. The results are shown in Figure 5 . The buffers with pH values from 2.0 to 5.0 were prepared from different ratios of 200.0 mmol / L acetic acid and sodium acetate solutions (HAc-NaAc). In the range of pH 2.0 - 5.0, the reduction peak current was larger at pH 4.0. As the pH further increased from 4.0 to 5.0, the reduction peak current gradually decreased. The pH of the buffer is a key influencing factor for the detection of titanium ions. The measurement error is small and the reduction peak current is large at pH 4.0, so the pH of the HAc-NaAc buffer is preferably 4.0.

[0076] Example 8: Effect of complexing agent concentration on the stripping peak signal

[0077] Ti(5-Br-PADAP) 4 There is a certain relationship between the reduction current on the titanium electrode and the concentration of 5-Br-PADAP in the sample. At concentrations below 4 mmol / L, the reduction current increases with the increase in the concentration of 5-Br-PADAP, as Figure 6 shown. However, if the concentration of 5-Br-PADAP continues to increase, the reduction peak of 5-Br-PADAP affects the reduction peak of Ti(5-Br-PADAP) 4 , resulting in an increase in the background current near the reduction peak of Ti(5-Br-PADAP) 4 . Therefore, 4 mmol / L 5-Br-PADAP is taken as the optimal concentration.

[0078] Example 9: Effect of interfering ions on the stripping peak signal

[0079] Figure 7 For the titanium-based electrochemical sensor prepared in Example 1, in the presence or absence of interfering ions (Ni² + , Co² + , Fe³ + , Cu² + , Fe² + , Mg² + , Ca² + , Mn² + or Cl -Adsorptive stripping voltammetry curves in the titanium complex electrolyte of (), with the ionic concentration being 100 μm. The results are as Figure 7 shown, for the Ti 4+ complex, the deviation of the stripping peak current does not exceed 2.8%, the peak position does not change significantly, and no other stripping peaks appear, indicating that the electrochemical sensor has good selectivity.

[0080] Example 10: Precision of Electrochemical Method for Determining Titanium Ions at Different Concentrations

[0081] This example evaluates the precision of the electrochemical method of the present invention for determining titanium ions at different concentrations. In the experiment, the titanium ion standard solution was directly added to the electrolyte solution to prepare titanium ion solutions with low concentration (50 pM), medium concentration (50 μM), and high concentration (50 mM). In these solutions, intra-day repeated determinations were carried out, that is, the same sample was continuously determined 5 times within one day, and inter-day determinations were carried out, that is, the same sample was determined within 5 consecutive days. By calculating the intra-day and inter-day coefficients of variation of titanium ions at different concentrations, the precision of the method was comprehensively investigated, and the results are shown in Table 1 in detail.

[0082] The experimental results show that the intra-day coefficients of variation of titanium ions are all less than 5.5%, and the inter-day coefficients of variation are all less than 6.3%, indicating that the electrochemical detection method of the present invention has good precision in determining titanium ions at different concentrations.

[0083] Table 1. Precision (n = 5)

[0084]

[0085] Example 11: Recovery Rate of Electrochemical Method for Determining Titanium Ions at Different Concentrations

[0086] This example examines the recovery rate of the electrochemical method of the present invention for determining titanium ions. After adding titanium ion standard solutions with low concentration (50 pM), medium concentration (50 μM), and high concentration (50 mM) to the electrolyte solution respectively, a recovery experiment was carried out by measuring the concentration of titanium ions in the solution before and after adding the titanium ion standard solution.

[0087] The formula for calculating the relative recovery rate is:

[0088] .

[0089] The results are shown in Table 2. The recovery rates of titanium ions at different concentrations are between 97.0% and 107.6%, and the maximum coefficient of variation is 5.0%, indicating that the electrochemical detection method of the present invention has good accuracy.

[0090] Table 2. Recovery Rate of Titanium Ions (n = 5)

[0091]

Claims

1. Application of a chemically modified titanium-based sensor in detecting titanium content, wherein the chemically modified titanium-based sensor is prepared by the following method: (1) Pretreatment of titanium electrode: polish the surface of titanium electrode to make it smooth and flat, and then perform ultrasonic cleaning and drying; (2) Chemical modification of titanium electrode: first, the pretreated titanium electrode obtained in step (1) is modified with nanomaterials, and then modified with functional molecules; The nanomaterial modification includes: 3 g of graphene oxide was dispersed in 500 mL of deionized water to prepare a 6 mg / mL graphene oxide dispersion, 200 mL of 40% hydroiodic acid aqueous solution was added for reduction, ultrasonic treatment was performed at 60° C. for 5 hours to promote the reaction, nanographene precipitation was obtained by centrifugation, and the precipitation was washed with ethanol and deionized water, and dried; 600 mg of nanographene powder was added to 100 mL of ethanol for ultrasonic dispersion to form a nanographene dispersion with a concentration of 6 mg / mL; the pretreated titanium electrode was completely immersed in the nanographene dispersion for 12-24 hours, and then the electrode was taken out and dried at 60-80° C. for 2-4 hours to make the nanographene firmly attached to the electrode surface, thereby obtaining a titanium / graphene electrode; The functional molecule modification includes: mixing pyrrole monomer and ethanol in a mass ratio of 1:10 to form a sol, stirring at 60°C for 2 hours and standing for 48 hours to form a PPy gel, evenly dropping 500 μL of the PPy gel on the clean titanium / graphene electrode surface, drying at room temperature, and finally heat treating at 80°C to solidify the film.

2. A method for detecting titanium content, comprising the step of using a chemically modified titanium-based sensor for detection, wherein the chemically modified titanium-based sensor is prepared by the following method: (1) Pretreatment of titanium electrode: polish the surface of titanium electrode to make it smooth and flat, and then perform ultrasonic cleaning and drying; (2) Chemical modification of titanium electrode: first, the pretreated titanium electrode obtained in step (1) is modified with nanomaterials, and then modified with functional molecules; The nanomaterial modification includes: 3 g of graphene oxide was dispersed in 500 mL of deionized water to prepare a 6 mg / mL graphene oxide dispersion, 200 mL of 40% hydroiodic acid aqueous solution was added for reduction, ultrasonic treatment was performed at 60° C. for 5 hours to promote the reaction, nanographene precipitation was obtained by centrifugation, and the precipitation was washed with ethanol and deionized water, and dried; 600 mg of nanographene powder was added to 100 mL of ethanol for ultrasonic dispersion to form a nanographene dispersion with a concentration of 6 mg / mL; the pretreated titanium electrode was completely immersed in the nanographene dispersion for 12-24 hours, and then the electrode was taken out and dried at 60-80° C. for 2-4 hours to make the nanographene firmly attached to the electrode surface, thereby obtaining a titanium / graphene electrode; The functional molecule modification includes: mixing pyrrole monomer and ethanol in a mass ratio of 1:10 to form a sol, stirring at 60°C for 2 hours and standing for 48 hours to form a PPy gel, evenly dropping 500 μL of the PPy gel on the clean titanium / graphene electrode surface, drying at room temperature, and finally heat treating at 80°C to solidify the film.

3. The method according to claim 2, characterized in that The method comprises the following steps: (1) Drawing a working curve: Place the three-electrode system in an electrolytic cell containing standard titanium solutions of different concentrations, add supporting electrolytes, buffer solutions, and organic complexing agent solutions, set potential parameters, start potential scanning, record current signals at different potentials, and draw a working curve based on the current signals and the corresponding titanium ion concentrations to ensure that the peak current shows a good linear relationship with the titanium ion concentration. (2) Sample detection: The actual sample is processed into a solution form suitable for detection to ensure that the titanium in the sample exists in the form of ions. The three-electrode system is placed in the sample solution, and potential scanning and current signal measurement are performed under the same experimental conditions as when drawing the working curve. According to the measured current signal, the corresponding titanium ion concentration is found from the working curve, thereby realizing the detection of the titanium content in the sample. The three-electrode system includes the chemically modified titanium-based sensor as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum wire electrode as the counter electrode.

4. The method according to claim 3, characterized in that In step (1), the potential parameter is -0.2 V as the enrichment potential, and the enrichment time is 2 minutes.

5. The method according to claim 3, characterized in that: In step (1), the dissolution potential scan range was set to -0.5 V to 0.5 V, and the scan rate was set to 50 mV / s.

6. The method according to claim 3, characterized in that In step (1), the supporting electrolyte is potassium chloride solution, the buffer solution is HAc-NaAc, and the organic complexing agent solution is 5-Br-PADAP.

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