Electrochemical sensing analysis method for nitrophenol by environmental hormone
阅读说明：本技术 环境激素对硝基酚的电化学传感分析方法 (Electrochemical sensing analysis method for nitrophenol by environmental hormone ) 是由 江吉周 何小苗 邹菁 白赛帅 于 2020-12-10 设计创作，主要内容包括：本发明公开了一种环境激素4-NP的电化学传感分析方法,将WO-(2.9)/g-C-3N-4阶梯型异质结超声分散在去离子水中得到分散液,所得分散液浓度为0.0002～0.01g/mL；在干净无杂质的裸玻碳电极上加1～10μL的WO-(2.9)/g-C-3N-4分散液进行修饰,然后在红外灯下烘烤3～10min,得到修饰电极；将修饰电极放在待测液体中进行DPV测试；若0.8～1.2V范围内出现一个明显的氧化峰,据此对待测液体进行定性检测。本发明在浓度为0.4～100μmol/L的范围时,氧化峰电流值与浓度呈良好的线性关系,检出限为0.13μmol/L,且具有良好的稳定性和重现性,可应用于实际水样中环境激素4-NP的检测。(The invention discloses an electrochemical sensing analysis method of environmental hormone 4-NP, which is implemented by mixing WO 2.9 /g‑C 3 N 4 Ultrasonically dispersing the stepped heterojunction in deionized water to obtain a dispersion liquid, wherein the concentration of the obtained dispersion liquid is 0.0002-0.01 g/mL; adding 1-10 mu L of WO on a clean and impurity-free bare glassy carbon electrode 2.9 /g‑C 3 N 4 Modifying the dispersion liquid, and then baking for 3-10 min under an infrared lamp to obtain a modified electrode; placing the modified electrode in liquid to be tested for DPV test; if an obvious oxidation peak appears in the range of 0.8-1.2V, the liquid to be detected is qualitatively detected according to the oxidation peak. When the concentration is in the range of 0.4-100 mu mol/L, the oxidation peak current value and the concentration have good linear relation, the detection limit is 0.13 mu mol/L, and the method has good stability and reproducibility and can be appliedAnd (3) detecting the environmental hormone 4-NP in an actual water sample.)
1. The electrochemical sensing analysis method of the environmental hormone 4-NP is characterized by comprising the following steps:
mixing WO2.9/g-C3N4Ultrasonically dispersing the stepped heterojunction in deionized water to obtain a dispersion liquid, wherein the concentration of the obtained dispersion liquid is 0.0002-0.01 g/mL;
adding 1-10 mu L of WO on a clean and impurity-free bare glassy carbon electrode2.9/g-C3N4Modifying the dispersion liquid, and then baking for 3-10 min under an infrared lamp to obtain a modified electrode;
placing the modified electrode in liquid to be tested to carry out differential pulse voltammetry test;
if an obvious oxidation peak appears in the range of 0.8-1.2V, the liquid to be detected is concluded to contain the environmental hormone 4-NP; thereby carrying out qualitative detection on the liquid to be detected.
2. The method for electrochemical sensing analysis of environmental hormone 4-NP as claimed in claim 1, further comprising the steps of:
preparing a 4-NP solution sample with a known concentration of 0.04-100 mu mol/L, respectively carrying out differential pulse voltammetry on the 4-NP solution sample with the known concentration by using a modified electrode, and calculating a linear equation according to the oxidation peak current and the corresponding 4-NP concentration: i isp0.0491c + 0.0908; c is the concentration of 4-NP,. mu.mol/L, Ipμ a for oxidation peak current; the concentration of 4-NP in the liquid to be detected is quantitatively detected.
3. The method for electrochemical sensing analysis of environmental hormone 4-NP as claimed in claim 1 wherein said WO2.9/g-C3N4The step-type heterojunction is prepared by adopting the following method:
(1) heating melamine to 500-600 ℃ at a speed of 3-12 ℃/min in a muffle furnace, keeping the temperature for 3-10h, and cooling to obtain faint yellow g-C3N4A block body;
(2) the obtained g-C3N4Placing the block in a high pressure reaction kettle with polytetrafluoroethylene lining, adding deionized water, mixing to obtain dispersion, and subjecting to g-C treatment with cell wall breaking ultrasonic instrument3N4Carrying out ultrasonic treatment on the dispersion liquid of the block; diluting the supernatant, placing in an ultrasonic cleaning machine, continuously performing ultrasonic treatment, and standing to obtain thin layer g-C3N4A dispersion liquid;
(3) formulation of WCl6Transferring the absolute ethyl alcohol solution into a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, sealing and heating to 150-200 ℃, and continuing for 10-15 hours; naturally cooling, washing the substrate with absolute ethyl alcohol for 3-5 times, and vacuum drying at 50-80 ℃ to obtain WO2.9；
(4) Mixing WO2.9With a thin layer g-C3N4Mixing the dispersion liquid in a penicillin bottle, and putting the penicillin bottle into an ultrasonic cleaner for ultrasonic treatment for 20-80 min at 80-140W to obtain WO2.9/g-C3N4A step-type heterojunction.
4. The method for electrochemical sensing analysis of environmental hormone 4-NP as claimed in claim 3, wherein the step 2 is performed by using a cell wall breaking ultrasonic instrument for g-C3N4The power of ultrasonic treatment of the block is 800-1500W, the starting/stopping time ratio is 10:2, and the treatment time is 2-4 h.
5. The method for electrochemical sensing analysis of environmental hormone 4-NP as claimed in claim 3, wherein the concentration of diluted supernatant in step 2 is 0.00001-0.0003 g/mL, and the power of continuous ultrasonic treatment is 80-140W for 1-4 h.
6. The method for electrochemical sensing analysis of environmental hormone 4-NP as claimed in claim 3 wherein WCl in step 36The concentration of the extract in the absolute ethyl alcohol solution is 1-10 g/L.
7. The method for electrochemical sensing analysis of environmental hormone 4-NP as claimed in claim 3, wherein WO in step 42.9And g-C3N4The mass ratio of (A) to (B) is 1 (0.006-0.3).
Technical Field
The invention belongs to the technical field of electrochemical sensing, and particularly relates to an electrochemical sensing analysis method of environmental hormone p-nitrophenol.
Background
The environmental hormone refers to chemical substances which externally interfere the internal secretion of organisms, and the chemical substances are similar to hormones and are combined with hormone receptors in human bodies to influence the original hormone amount in the organisms, so that normal hormone imbalance is caused, the metabolic balance in the organisms is interfered, and the normal physiological function of the organisms is further influenced. Among them, the phenol environmental hormone has the highest attention, and as industrialization develops and environmental pollution increases, the phenol environmental hormone has increasing residue in the environment, has mutagenic, cytotoxic and phytotoxic effects, and is considered as a main priority pollutant in industrial wastewater. According to statistics, p-nitrophenol (4-NP) is one of the most harmful and toxic phenol environmental hormones, and is widely applied to production of pesticides, herbicides, synthetic dyes and the like at present, and the 4-NP which is inhaled or ingested by a human body and remains the environmental hormone causes headache, sleepiness, nausea and cyanosis, and finally causes serious harm to the health of the human body and the environment. The current method for detecting residual environmental hormone 4-NP in the environment mainly uses analytical instruments such as a liquid chromatograph-mass spectrometer, an inductively coupled plasma mass spectrometer and the like which have strong specialization and high testing cost. Therefore, it is urgently needed to develop a rapid, sensitive and real-time analysis method for detecting the environmental hormone 4-NP.
g-C3N4Has the advantages of high hardness, low density, high chemical stability, strong wear resistance, good biocompatibility, no toxicity, rich source of synthesized precursor, easy functionalization of surface and the like, and g-C3N4Has a similar structure of graphene, can form pi-pi stacking interaction with aromatic environmental hormone molecules, and can accelerate environmental hormone analytes to be in g-C3N4And (4) enriching the surface. But has wider band gap, serious carrier recombination, lack of surface active sites, thicker lamella and smaller specific surface areaAnd the like limit the application of the catalyst in the fields of photoelectrocatalysis and the like.
Disclosure of Invention
The invention aims to provide an electrochemical sensing analysis method for efficiently detecting environmental hormone 4-NP, which has the advantages of low manufacturing cost, simple operation, high efficiency and sensitivity, and can be successfully applied to the detection of 4-NP in an actual water sample.
In order to achieve the purpose, the technical scheme is as follows:
the electrochemical sensing analysis method of the environmental hormone 4-NP comprises the following steps:
mixing WO2.9/g-C3N4Ultrasonically dispersing the stepped heterojunction in deionized water to obtain a dispersion liquid, wherein the concentration of the obtained dispersion liquid is 0.0002-0.01 g/mL;
adding 1-10 mu L of WO on a clean and impurity-free bare glassy carbon electrode2.9/g-C3N4Modifying the dispersion liquid, and then baking for 3-10 min under an infrared lamp to obtain a modified electrode;
placing the modified electrode in liquid to be tested to carry out Differential Pulse Voltammetry (DPV) test;
if an obvious oxidation peak appears in the range of 0.8-1.2V, the liquid to be detected is concluded to contain the environmental hormone 4-NP; thereby carrying out qualitative detection on the liquid to be detected.
According to the scheme, the method further comprises the following steps:
preparing a 4-NP solution sample with a known concentration of 0.04-100 mu mol/L, respectively carrying out differential pulse voltammetry on the 4-NP solution sample with the known concentration by using a modified electrode, and calculating a linear equation according to the oxidation peak current and the corresponding 4-NP concentration: i isp0.0491c + 0.0908; c is the concentration of 4-NP,. mu.mol/L, Ipμ a for oxidation peak current; the concentration of 4-NP in the liquid to be detected is quantitatively detected.
According to the above scheme, said WO2.9/g-C3N4The step-type heterojunction is prepared by adopting the following method:
heating melamine to 500-600 ℃ at a speed of 3-12 ℃/min in a muffle furnace, keeping the temperature for 3-10h, and cooling to obtain faint yellow g-C3N4A block body;
the obtained g-C3N4Placing the block in a high pressure reaction kettle with polytetrafluoroethylene lining, adding deionized water, mixing to obtain dispersion, and subjecting to g-C treatment with cell wall breaking ultrasonic instrument3N4Carrying out ultrasonic treatment on the dispersion liquid of the block; diluting the supernatant, placing in an ultrasonic cleaning machine, continuously performing ultrasonic treatment, and standing to obtain thin layer g-C3N4A dispersion liquid;
formulation of WCl6Transferring the absolute ethyl alcohol solution into a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, sealing and heating to 150-200 ℃, and continuing for 10-15 hours; naturally cooling, washing the substrate with absolute ethyl alcohol for 3-5 times, and vacuum drying at 50-80 ℃ to obtain WO2.9；
Mixing WO2.9With a thin layer g-C3N4Mixing the dispersion liquid in a penicillin bottle, and putting the penicillin bottle into an ultrasonic cleaner for ultrasonic treatment for 20-80 min at 80-140W to obtain WO2.9/g-C3N4A step-type heterojunction.
According to the scheme, a cell wall breaking ultrasonic instrument is used for measuring the g-C3N4The power of ultrasonic treatment of the block is 800-1500W, the starting/stopping time ratio is 10:2, and the treatment time is 2-4 h.
According to the scheme, the concentration of the diluted supernatant is 0.00001-0.0003 g/mL, and the continuous ultrasonic treatment power is 80-140W, and the treatment time is 1-4 h.
According to the scheme, WCl6The concentration of the extract in the absolute ethyl alcohol solution is 1-10 g/L.
According to the above scheme, WO2.9And g-C3N4The mass ratio of (A) to (B) is 1 (0.006-0.3).
The invention has the beneficial effects that:
the invention prepares WO with enhanced current signal on the surface of glassy carbon electrode2.9/g-C3N4A step-type heterojunction material, and develops an electrochemical sensing analysis method for efficiently detecting environmental hormones.
The present invention utilizes WO2.9Nanoparticles and g-C3N4Of nanosheetsElectrostatic self-assembly to prepare WO2.9/g-C3N4The oxygen vacancy mediated stepped heterojunction has simple synthesis and low cost. Due to WO2.9And g-C3N4Recombination to form an oxygen vacancy mediated stepped heterojunction, WO2.9Due to the introduction of oxygen vacancies in the nanoparticles, excitons can be effectively dissociated into free charge carriers, thereby improving the electrocatalytic activity related to the carriers. Meanwhile, the formation of the stepped heterojunction can inhibit the recombination of useful electrons and holes on a heterointerface, so that the electrocatalysis rate of the surface of the modified electrode is improved.
When the concentration of the environmental hormone 4-NP is in the range of 0.4-100 mu mol/L, the oxidation peak current value on the modified electrode and the concentration form a good linear relation, and the detection limit is 0.13 mu mol/L; WO2.9/g-C3N4The modified electrode has good stability and reproducibility when detecting the environmental hormone 4-NP; in addition, the sensing analysis method is also successfully applied to the detection of the environmental hormone 4-NP in an actual water sample.
Drawings
FIG. 1: differential pulse voltammogram of the environmental hormone 4-NP at different modified electrodes.
Detailed Description
The following examples further illustrate the technical solutions of the present invention, but should not be construed as limiting the scope of the present invention.
Example 1:
WO2.9/g-C3N4preparing a step type heterojunction:
weighing 2-10 g of melamine, adding the melamine into a ceramic crucible, heating and stirring the mixture uniformly, putting the mixture into a muffle furnace for heating at a heating rate of 3-12 ℃/min and a heating temperature of 500-600 ℃, keeping the temperature for 3-10h, and cooling the mixture to obtain light yellow g-C3N4And (3) powder. Then g-C is added3N4Placing the cell in a cell wall breaking instrument for ultrasonic treatment, wherein the ultrasonic power is 800-1500W, and the ultrasonic treatment is started: the stop time ratio is 10:2, and the ultrasonic time is 2-4 h. Taking 2-10 mL of supernatant, diluting to 0.5-1.5L, carrying out ultrasonic treatment at the power of 80-140W for 1-4 h, standing overnight to obtain a thin layerg-C3N4A dispersion liquid; 0.05 to 0.20g of WCl6Placing the solution in 20-50 mL of absolute ethyl alcohol, performing ultrasonic treatment to completely dissolve the solution, wherein the ultrasonic power is 80-140W, the ultrasonic time is 3-10 min, transferring the solution into a stainless steel high-pressure reaction kettle with a capacity of 50-100 mL and a polytetrafluoroethylene lining, sealing and heating the reaction kettle to 150-200 ℃ for 10-15 h, after the reaction is finished, naturally cooling the reaction kettle to room temperature, thoroughly washing the substrate with absolute ethyl alcohol for 3-5 times, and drying the substrate in a vacuum drying oven at 50-80 ℃ to obtain WO2.9(ii) a Weighing 0.001-0.05 g of WO2.9Placing the mixture into a penicillin bottle, and adding 5-10 ml of thin layer g-C3N4Dispersing liquid, namely putting a penicillin bottle in an ultrasonic cleaner for ultrasonic treatment, wherein the ultrasonic power is 80-140W, and the ultrasonic time is 20-80 min, so as to prepare WO2.9/g-C3N4A step-type heterojunction.
Preparing a modified electrode:
mixing WO2.9/g-C3N4And adding the stepped heterojunction powder into deionized water, and uniformly dispersing by ultrasonic, wherein the ultrasonic power is 80-140W, and the ultrasonic time is 5-30 min. Simultaneously using 0.02-1 mu mAl for glassy carbon electrode2O3Polishing the polishing powder to a mirror surface, and cleaning the mirror surface by using deionized water. Removing 1 to 10 mu LWO2.9/g-C3N4Dripping the dispersion liquid on the surface of a glassy carbon electrode, baking for 3-10 min under an infrared lamp, and observing a layer of blue film on the surface of the electrode to obtain WO2.9/g-C3N4And modifying the electrode.
Modified WO2.9/g-C3N4Electrode and g-C3N4Electrode, WO2.9Electrode, WO3/g-C3N4Electrode, WO3And respectively carrying out DPV scanning on the electrode and the bare electrode in a solution to be detected containing the environmental hormone 4-NP. As can be seen from FIG. 1, WO2.9/g-C3N4The current of the environmental hormone 4-NP measured by the modified electrode is obviously higher than that of other electrodes. Conditions such as buffer solution, pH value and the like are optimized to maximize the oxidation peak current of the environmental hormone 4-NP.
Example 2
Preparing a sample of environmental hormone 4-NP at a known concentration of 0.04 to 100. mu.M, and mixing WO2.9/g-C3N4The modified electrode is subjected to DPV scanning in the environmental hormone 4-NP, and a linear equation is calculated according to the oxidation peak current and the corresponding concentration of the environmental hormone 4-NP: i isp＝0.0491c+0.0908(R20.9985); c is the concentration of the environmental hormone 4-NP (. mu.mol/L), IpThe oxidation peak current (. mu.A). According to the equation, the unknown concentration of the environmental hormone 4-NP can be quantitatively detected.
Example 3
Referring to example 1, preparation of WO2.9/g-C3N4And (3) a modified electrode, namely putting the modified electrode into a sodium acetate-acetic acid buffer solution containing a substance to be detected and having a pH value of 3-7 to perform DPV scanning, and measuring the content of the environmental hormone 4-NP by measuring the current intensity corresponding to the electrocatalytic oxidation peak of the environmental hormone 4-NP. The optimum pH was 5, with the peak current being the greatest. Analyzing the electron proton transfer quantity according to the relation between pH and voltage, and performing linear regression analysis on the pH value and the voltage to obtain Epa(V)＝-0.06019pH+1.376 (R20.993) according to the formula dEpc/dpH0.059m/n, where m is the number of protons and n is the number of electrons, to yield dEpc/dpH0.06019, close to 0.059, m/n is 1, i.e. in WO2.9/g-C3N4On the electrode, the number of transferred electrons in the 4-NP electrocatalytic oxidation process is equal to the number of protons.
Example 4
WO2.9/g-C3N4Preparation of modified electrode referring to example 1, the modified electrode was placed in a phosphate buffer system containing the analyte to be measured, DPV scanning was performed, and the content of the environmental hormone 4-NP in the water sample was obtained by measuring the current intensity corresponding to the electrocatalytic oxidation peak of the environmental hormone 4-NP according to the linear equation in example 2.
Example 5
The method is applied to a water sample in an actual environment, the taken water sample is filtered to be clear, and the environmental hormone 4-NP is detected. Under the optimal condition, a differential pulse voltammetry test is carried out, the concentration of 4-NP is calculated by adopting a standard addition method, the recovery rate is 98.8-108.8% and the Relative Standard Deviation (RSD) is within 4.8% according to the linear equation of the oxidation peak current obtained in the embodiment 2 and the corresponding concentration of the environmental hormone 4-NP.
Example 6
Adding pyrocatechol, hydroquinone and Ca into a 4-NP solution with a proper concentration and 10-200 times of the amount of the catechol, the hydroquinone and the Ca2+、Cu2+And 20-300 times of glucose and Na2+、Mg2+、K+、Cl-、CO3-And (3) carrying out interference test on the plasma, and finding that the substances do not interfere with the detection of the environmental hormone 4-NP, which shows that the electrochemical sensing analysis method has good interference resistance.