CN105928996B - Electrochemical detection device for preparing and assembling graphene oxide and polyaniline modified electrode - Google Patents
Electrochemical detection device for preparing and assembling graphene oxide and polyaniline modified electrode Download PDFInfo
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- G—PHYSICS
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Abstract
The invention provides an electrochemical detection device for preparing a graphene oxide and polyaniline modified electrode by a novel electrode, which comprises the following components: ultrasonically dispersing graphene oxide in a mixed solution containing polyaniline and Nafion to obtain GO-PAN-Nafion turbid liquid; and uniformly coating the GO-PAN-Nafion suspension on the surface of the glassy carbon electrode after polishing, cleaning and blow-drying treatment to obtain the GO-PAN-Nafion/GCE. The developed graphene oxide material meets the requirements of heavy metal ion detection and deep removal in water. The electrode material with high electrochemical activity is applied to the rapid determination of heavy metals in the water body of the electrochemical sensor, has the advantages of simple sample treatment, low cost, high speed, simultaneous detection of trace heavy metals and the like, and has great economic and social benefits after the development and industrialization of the detection and treatment technology of heavy metal water pollution in China are promoted.
Description
Technical Field
The invention belongs to the field of analysis and detection, and particularly relates to an electrochemical detection device which is assembled by preparing a graphene oxide and polyaniline modified electrode by using a novel electrode.
Background
The chemically modified electrode is characterized in that molecular design is carried out on the surface of the electrode by a chemical modification method, molecules, ions and polymers with excellent chemical properties are fixed on the surface of the electrode to form a certain microstructure, and a certain specific chemical and electrochemical property is given to the electrode so as to carry out a desired reaction with high selectivity, so that the chemically modified electrode has unique superiority in improving selectivity and sensitivity. The method utilizes a plurality of available potential fields provided by the microstructure on the surface of the chemically modified electrode to effectively separate and enrich the object to be measured, further improves the selectivity by controlling the electrode potential, and combines the sensitivity of the measuring method and the selectivity of the chemical reaction of the modifying agent to form an ideal system integrating the separation, the enrichment and the selectivity.
Anodic Stripping Voltammetry (ASV) is a main electrochemical method for detecting heavy metal ions, but the traditional ASV mainly adopts a mercury-plated membrane electrode as a working electrode, and mercury is very toxic to human bodies, so that a novel environment-friendly electrode material needs to be developed to replace mercury. Because the specific area of the modified graphene oxide is large, the adsorption of the carbonaceous substance on the heavy metal ions mainly occurs on acidic functional groups (carboxyl groups and lactone acid groups), the surface of the graphene oxide contains a large amount of hydroxyl, carboxyl and oxygen-containing functional groups, the surface of the graphene oxide has stronger adsorption force on the heavy metal ions, and the detection sensitivity of the electrode can be improved.
Patent CN201510518917.5 discloses a method for preparing an electrochemical sensor for synchronously detecting the content of mercury, copper, lead and cadmium ions, which utilizes an electrochemical deposition method to dope graphene oxide with nitrogen to prepare a modified glassy carbon electrode, and performs electrochemical detection on the mercury, copper, lead and cadmium ions in a solution with acetic acid/sodium acetate as a supporting electrolyte. But the detection limit is higher, and the requirement of detecting the trace of part of heavy metal elements cannot be met.
Polyaniline (PAN), a polymer compound, has special electrical and optical properties, and can have electrical conductivity and electrochemical properties after being doped. After certain treatment, various devices and materials with special functions can be prepared, such as urease sensors which can be used as biological or chemical sensors, electron field emission sources, electrode materials which have more excellent reversibility in the charging and discharging processes compared with the traditional lithium electrode materials, selective membrane materials, antistatic and electromagnetic shielding materials, conductive fibers, anticorrosion materials and the like. Polyaniline has been widely studied and applied because of its easily available raw materials, simple synthesis process, good chemical and environmental stability, and the like.
Disclosure of Invention
In order to overcome the problems and improve the detection sensitivity, the electrode modification material is improved, and graphene oxide is bonded on the surface of the glassy carbon electrode through the bonding effect of the Nafion solution, but experiments show that when the mass fraction of Nafion is more than 0.5%, the solubility of the graphene oxide is poor, agglomeration is easy to occur, a uniform dispersion system cannot be formed, and the conductivity of the electrode is reduced. Therefore, a certain amount of polyaniline is added into the Nafion solution, and due to the non-localized P-electron conjugated structure of the polyaniline, the polyaniline can be uniformly deposited in the middle of graphene sheet layers after doping, so that the stacking of graphene nano sheets can be effectively prevented, the dispersion degree of graphene oxide is improved, and the active surface area is increased. In addition, the conductivity of the Nafion film is effectively improved by doping polyaniline, a structural carrier of a multilevel pore channel is constructed while the permselectivity of the Nafion film is not damaged, and the defect of poor conductivity of the Nafion film is overcome by fully utilizing the ultrahigh specific surface area and excellent conductivity of graphene.
In order to achieve the purpose, the invention adopts the following technical scheme:
a graphene oxide and polyaniline-modified electrode comprising:
a glassy carbon electrode;
the graphene oxide-polyaniline-Nafion layer is coated on the glassy carbon electrode;
the graphene oxide-polyaniline-Nafion layer is formed by uniformly mixing graphene oxide, polyaniline and Nafion.
Preferably, in the graphene oxide-polyaniline-Nafion layer, the ratio of graphene oxide: polyaniline: the mass ratio of Nafion is as follows: 4 to 5:1 to 2X 103。
The experiment of the invention finds that: and (3) graphene oxide: polyaniline: among Nafion, when Nafion proportionality coefficient is less than 1X 103The selective permeability of the formed film is poor, and the accuracy and precision of the electrode are reduced; when the Nafion proportionality coefficient is larger than 2 multiplied by 103In the process, the conductivity of the electrode is reduced, and the graphene oxide is not uniformly dispersed and is easy to agglomerate.
When the proportionality coefficient of the polyaniline is more than 2, the permselectivity of the formed film is reduced, the film is easily interfered by other impurity heavy metal ions, and the chemical stability of the formed film is reduced; when the proportionality coefficient of polyaniline is less than 1, an effective multi-level pore channel system cannot be formed, and the electrode conductivity is greatly reduced.
The invention also provides a graphene oxide and polyaniline modified electrode sensor which is prepared by taking any one of the electrodes as a working electrode.
The invention also provides a preparation method of the graphene oxide and polyaniline modified electrode, which comprises the following steps:
ultrasonically dispersing graphene oxide in a mixed solution of polyaniline and Nafion to obtain GO-PANPAN-Nafion turbid liquid;
and uniformly coating the GO-PAN-Nafion suspension on the surface of the glassy carbon electrode after polishing, cleaning and blow-drying treatment to obtain the GO-PAN-Nafion/GCE.
Preferably, graphene oxide is contained in the GO-PAN-Nafion suspension; polyaniline: the mass ratio of Nafion is as follows: 4 to 5:1 to 2X 103。
Preferably, the concentration of the polyaniline in the mixed solution of the polyaniline and Nafion is 0.5-1.0 mgL-1The mass fraction of Nafion is 0.5-1.0%.
The invention also provides an electrochemical detection method of the graphene oxide and polyaniline modified electrode in detecting trace heavy metal ions in water, which comprises the steps of
The modified graphene oxide composite modified electrode is used as a working electrode, and heavy metal ions in the water body are respectively measured by adopting an anodic stripping voltammetry method.
Preferably, the heavy metal ions include: copper, lead, zinc, iron, cobalt, nickel, manganese, cadmium, mercury, tungsten, molybdenum, gold and silver.
More preferably, the heavy metal ion is lead.
Preferably, the detection parameters of the anodic stripping voltammetry are as follows:
the electro-deposition potential is-1.4V, and the electro-deposition time is 180 s;
the static potential is-1.35V, and the static time is 10 s;
the scanning speed is 5mV/s, and the scanning range is-1.4V to-1.35V.
Preferably, in the detection process of the anodic stripping voltammetry, the electrolyte contains 0.1M acetate and 400 mu gL-1And (7) PAN. The experiment of the invention finds that: adding 400 mu gL of electrolyte-1And the detection precision of the PAN is improved by about 1.2-1.7%. Probably due to the presence of polyaniline salt which promotes the metal enrichment and dissolution efficiency.
Studies have also shown that: and sequentially coating the graphene oxide dispersion liquid, the polyaniline solution and the Nafion solution on the surface of the glassy carbon electrode to form a corresponding graphene oxide layer, a polyaniline film layer and a Nafion film layer, wherein the obtained multilayer modified electrode is approximately equivalent to the detection results of the graphene oxide and polyaniline modified electrode.
Therefore, the present invention also provides a graphene oxide and polyaniline modified multilayer electrode, comprising:
a base electrode;
the graphene oxide is arranged on the outer surface of the substrate electrode;
the polyaniline layer is arranged on the outer surface of the graphene oxide;
and the Nafion layer is arranged on the outer surface of the polyaniline layer.
Preferably, the substrate electrode is a glassy carbon electrode.
The invention also provides an electrochemical sensor modified by graphene oxide and polyaniline, wherein the electrode sensor is an electrolytic cell, and the electrolytic cell comprises: the working electrode is any one of the multilayer electrode, the auxiliary electrode, the reference electrode and the electrolyte arranged at the bottom of the electrolytic cell.
Preferably, the auxiliary electrode is a platinum wire electrode.
Preferably, the reference electrode is a calomel reference electrode
Preferably, a magnetic stirrer is also arranged in the electrolytic cell.
The invention has the beneficial effects that:
1) and after the modified graphene oxide material is subjected to ultrasonic dispersion, preparing a composite modified electrode on the surface of the glassy carbon electrode through an adhesive, and using the composite modified electrode for electrochemical test of the next experiment. The heavy metal ion to be measured is first enriched on the working electrode through electrolysis under proper base solution and applied voltage, and then the applied voltage is scanned in positive direction to make it oxidized and dissolved to obtain anode dissolved peak, which can be used as qualitative and quantitative analysis of heavy metal ion according to peak potential and peak current.
2) The developed graphene oxide material meets the requirements of heavy metal ion detection and deep removal in water. The electrode material with high electrochemical activity is applied to the rapid determination of heavy metals in the water body of the electrochemical sensor, has the advantages of simple sample treatment, low cost, high speed, simultaneous detection of trace heavy metals and the like, and has great economic and social benefits after the development and industrialization of the detection and treatment technology of heavy metal water pollution in China are promoted.
3) Detecting trace heavy metal ions in water by adopting graphene material modified glassy carbon electrode, wherein lead ions (Pb) are detected2 +) And cadmium ion (Cd)2+) The detection limit of (A) is up to 0.2ug/L and 0.1ug/L respectively. Good selectivity (Na)+、Ca2+、K+、Al3+、Li+、Cr3+No response to plasma), good stability and the like, and the prepared glassy carbon electrode modified by the graphene material can be used for simultaneously measuring the content of heavy metal ions in the environment.
4) The preparation method is simple, strong in practicability and easy to popularize.
Drawings
FIG. 1 is a schematic structural diagram of an electrochemically modified electrode according to the present invention.
The electrode structure comprises a substrate electrode (glassy carbon electrode) 1, a graphene oxide layer modified on the outer surface of the substrate electrode 2, a polyaniline layer modified on the outer surface of the graphene oxide layer 3 and a Nafion layer modified on the outer surface of the polyaniline layer 4.
Detailed Description
The invention is further illustrated by the following examples.
Example 1
Adding 1.0mL of graphene oxide aqueous solution (with the concentration of 2.3mg/mL) into 0.75% of Nafion solution (containing 0.5mg/L polyaniline solution) by mass fraction, uniformly mixing, and performing ultrasonic dispersion for 30min to form GO-PAN-Nafion is suspended. A glassy carbon electrode (diameter 3mm) containing 0.3 and 0.05 μm of Al in this order2O3Polishing the slurry chamois leather to a mirror surface, then ultrasonically cleaning the slurry chamois leather in absolute ethyl alcohol, dilute nitric acid and secondary water in sequence, and finally washing the slurry chamois leather by using the secondary water. And after the surface of the electrode is dried by using nitrogen, dropwise adding 5 mu L of GO-PAN-Nafion suspension in the center of the electrode by using a micro-syringe, after the solvent is volatilized, washing the surface of the electrode by using deionized water and drying in the air to obtain the GO-PAN-Nafion composite membrane modified glassy carbon electrode which is marked as GO-PAN-Nafion/GCE.
Electrochemical determination of four ions of mercury, copper, lead and cadmium: four metal ions of different concentrations were added to acetate buffer solution (acetate concentration 1mol/L, containing Bi of 400. mu.g/L) of pH 4.5, respectively3+) And simultaneously measuring the four ions by using GO-PAN-Nafion/GCE in combination with anodic stripping voltammetry.
The detection parameters are as follows:
the electro-deposition potential is-1.4V, and the electro-deposition time is 180 s;
the static potential is-1.35V, and the static time is 10 s;
the scanning speed is 5mV/s, and the scanning range is-1.4V to-1.35V.
The results show that: the linear increase of the peak current indicates that the sensing electrode can successfully detect four metal ions with unknown concentrations, and the modified electrode has a good linear relation, a wider linear range, higher sensitivity and lower detection limit to the four metal ions.
And (3) evaluating the performance of the electrochemical sensor for detecting four ions of mercury, copper, lead and cadmium: the GO-PAN-Nafion/GCE has strong selectivity on four ions of mercury, copper, lead and cadmium, and has strong selectivity on Na+、Ca2+、K+、Al3+、Li+、Cr3+The plasma has stronger anti-interference capability. Even in the presence of various anions and cations, e.g. Br-、Cl-、NO3-、H2PO4-、SO4 2-In the complex environment with the simultaneous existence of the GO-PAN-Nafion/GCE, the electrochemical response of the GO-PAN-Nafion/GCE to four ions of mercury, copper, lead and cadmium is not obviously changed, so that some common yin and yang are eliminatedInterference of ions.
Wherein, lead ion (Pb) is included2+) And cadmium ion (Cd)2+) The detection limit of (a) is 0.211ug/L and 0.111ug/L respectively.
Example 2
Adding 1.25mL of graphene oxide aqueous solution (the concentration is 2.3mg/mL) into 1.0% by mass of Nafion solution (containing polyaniline salt with the concentration of 1.0 mg/L), uniformly mixing, and performing ultrasonic dispersion for 30min to form GO-PAN-Nafion suspension. A glassy carbon electrode (diameter 3mm) containing 0.3 and 0.05 μm of Al in this order2O3Polishing the slurry chamois leather to a mirror surface, then ultrasonically cleaning the slurry chamois leather in absolute ethyl alcohol, dilute nitric acid and secondary water in sequence, and finally washing the slurry chamois leather by using the secondary water. And after the surface of the electrode is dried by using nitrogen, dropwise adding 5 mu LGO-PAN-Nafion suspension in the center of the electrode by using a micro-syringe, after the solvent is volatilized, washing the surface of the electrode by using deionized water and drying in the air to obtain the GO-PAN-Nafion composite membrane modified glassy carbon electrode which is marked as GO-PAN-Nafion/GCE.
Electrochemical determination of four ions of mercury, copper, lead and cadmium: adding four metal ions with different concentrations into acetate buffer solution (acetate concentration is 1mol/L, wherein PAN with concentration of 400 mug/L) with pH of 4.5, simultaneously measuring the four ions by using GO-PAN-Nafion/GCE in combination with anodic stripping voltammetry,
the detection parameters are as follows:
the electro-deposition potential is-1.4V, and the electro-deposition time is 180 s;
the static potential is-1.35V, and the static time is 10 s;
the scanning speed is 5mV/s, and the scanning range is-1.4V to-1.35V.
The results show that: the linear increase of the peak current indicates that the sensing electrode can successfully detect four metal ions with unknown concentrations, and the modified electrode has a good linear relation, a wider linear range, higher sensitivity and lower detection limit to the four metal ions.
And (3) evaluating the performance of the electrochemical sensor for detecting four ions of mercury, copper, lead and cadmium: the GO-PAN-Nafion/GCE has strong selectivity on four ions of mercury, copper, lead and cadmium, and has strong selectivity on Na+、Ca2+、K+、Al3+、Li+、Cr3+The plasma has stronger anti-interference capability. Even in the presence of various anions and cations, e.g. Br-、Cl-、NO3-、H2PO4-、SO4 2-In a complex environment with the same existence, the electrochemical response of GO-PAN-Nafion/GCE to mercury, copper, lead and cadmium ions is not obviously changed, so that the interference of common anions and cations is eliminated.
Wherein, lead ion (Pb) is included2+) And cadmium ion (Cd)2+) The detection limit of (A) reaches 0.216ug/L and 0.113ug/L respectively.
Example 3
Adding 1.2mL of graphene oxide aqueous solution (with the concentration of 2.3mg/mL) into 0.8% of Nafion solution (containing 0.75mg/L of polyaniline solution) by mass fraction, uniformly mixing, and performing ultrasonic dispersion for 30min to form GO-PAN-Nafion suspension. A glassy carbon electrode (diameter 3mm) containing 0.3 and 0.05 μm of Al in this order2O3Polishing the slurry chamois leather to a mirror surface, then ultrasonically cleaning the slurry chamois leather in absolute ethyl alcohol, dilute nitric acid and secondary water in sequence, and finally washing the slurry chamois leather by using the secondary water. And after the surface of the electrode is dried by using nitrogen, dropwise adding 5 mu L of GO-PAN-Nafion suspension in the center of the electrode by using a micro-syringe, after the solvent is volatilized, washing the surface of the electrode by using deionized water and drying in the air to obtain the GO-PAN-Nafion composite membrane modified glassy carbon electrode which is marked as GO-PAN-Nafion/GCE.
Electrochemical determination of four ions of mercury, copper, lead and cadmium: adding four metal ions with different concentrations into acetate buffer solution (acetate concentration is 1mol/L, wherein PAN with concentration of 400 mug/L) with pH of 4.5, simultaneously measuring the four ions by using GO-PAN-Nafion/GCE in combination with anodic stripping voltammetry,
the detection parameters are as follows:
the electro-deposition potential is-1.4V, and the electro-deposition time is 180 s;
the static potential is-1.35V, and the static time is 10 s;
the scanning speed is 5mV/s, and the scanning range is-1.4V to-1.35V.
The results show that: the linear increase of the peak current indicates that the sensing electrode can successfully detect four metal ions with unknown concentrations, and the modified electrode has a good linear relation, a wider linear range, higher sensitivity and lower detection limit to the four metal ions.
And (3) evaluating the performance of the electrochemical sensor for detecting four ions of mercury, copper, lead and cadmium: the GO-PAN-Nafion/GCE has strong selectivity on four ions of mercury, copper, lead and cadmium, and has strong selectivity on Na+、Ca2+、K+、Al3+、Li+、Cr3+The plasma has stronger anti-interference capability. Even in the presence of various anions and cations, e.g. Br-、Cl-、NO3-、H2PO4-、SO4 2-In a complex environment with the same existence, the electrochemical response of GO-PAN-Nafion/GCE to mercury, copper, lead and cadmium ions is not obviously changed, so that the interference of common anions and cations is eliminated.
Wherein, lead ion (Pb) is included2+) And cadmium ion (Cd)2+) The detection limit of (A) reaches 0.208ug/L and 0.109ug/L respectively.
Example 4
Adding 1.0mL of graphene oxide aqueous solution (with the concentration of 2.3mg/mL) into 0.8% of Nafion solution (containing 0.75mg/L of polyaniline solution) by mass fraction, uniformly mixing, and performing ultrasonic dispersion for 30min to form GO-PAN-Nafion suspension. A glassy carbon electrode (diameter 3mm) containing 0.3 and 0.05 μm of Al in this order2O3Polishing the slurry chamois leather to a mirror surface, then ultrasonically cleaning the slurry chamois leather in absolute ethyl alcohol, dilute nitric acid and secondary water in sequence, and finally washing the slurry chamois leather by using the secondary water. And after the surface of the electrode is dried by using nitrogen, dropwise adding 5 mu LGO-PAN-Nafion suspension in the center of the electrode by using a micro-syringe, after the solvent is volatilized, washing the surface of the electrode by using deionized water and drying in the air to obtain the GO-PAN-Nafion composite membrane modified glassy carbon electrode which is marked as GO-PAN-Nafion/GCE.
Electrochemical determination of four ions of mercury, copper, lead and cadmium: adding four metal ions with different concentrations into acetate buffer solution (acetate concentration is 1mol/L, wherein PAN with concentration of 400 mug/L) with pH of 4.5, simultaneously measuring the four ions by using GO-PAN-Nafion/GCE in combination with anodic stripping voltammetry,
the detection parameters are as follows:
the electro-deposition potential is-1.4V, and the electro-deposition time is 180 s;
the static potential is-1.35V, and the static time is 10 s;
the scanning speed is 5mV/s, and the scanning range is-1.4V to-1.35V.
The results show that: the linear increase of the peak current indicates that the sensing electrode can successfully detect four metal ions with unknown concentrations, and the modified electrode has a good linear relation, a wider linear range, higher sensitivity and lower detection limit to the four metal ions.
And (3) evaluating the performance of the electrochemical sensor for detecting four ions of mercury, copper, lead and cadmium: the GO-PAN-Nafion/GCE has strong selectivity on four ions of mercury, copper, lead and cadmium, and has strong selectivity on Na+、Ca2+、K+、Al3+、Li+、Cr3+The plasma has stronger anti-interference capability. Even in the presence of various anions and cations, e.g. Br-、Cl-、NO3-、H2PO4-、SO4 2-In a complex environment with the same existence, the electrochemical response of GO-PAN-Nafion/GCE to mercury, copper, lead and cadmium ions is not obviously changed, so that the interference of common anions and cations is eliminated.
Wherein, lead ion (Pb) is included2+) And cadmium ion (Cd)2+) The detection limit of (A) reaches 0.211ug/L and 0.108ug/L respectively.
Example 5
A graphene oxide and polyaniline-modified electrode comprising:
a base electrode 1;
a polyaniline layer 3 disposed on the outer surface of the graphene oxide;
and the Nafion layer 4 is arranged on the outer surface of the polyaniline layer.
The detection parameters are as follows:
the electro-deposition potential is-1.4V, and the electro-deposition time is 180 s;
the static potential is-1.35V, and the static time is 10 s;
the scanning speed is 5mV/s, and the scanning range is-1.4V to-1.35V.
The results show that: the linear increase of the peak current indicates that the sensing electrode can successfully detect four metal ions with unknown concentrations, and the modified electrode has a good linear relation, a wider linear range, higher sensitivity and lower detection limit to the four metal ions.
And (3) evaluating the performance of the electrochemical sensor for detecting four ions of mercury, copper, lead and cadmium: the GO-PAN-Nafion/GCE has strong selectivity on four ions of mercury, copper, lead and cadmium, and has strong selectivity on Na+、Ca2+、K+、Al3+、Li+、Cr3+The plasma has stronger anti-interference capability. Even in the presence of various anions and cations, e.g. Br-、Cl-、NO3-、H2PO4-、SO4 2-In a complex environment with the same existence, the electrochemical response of GO-PAN-Nafion/GCE to mercury, copper, lead and cadmium ions is not obviously changed, so that the interference of common anions and cations is eliminated.
Wherein, lead ion (Pb) is included2+) And cadmium ion (Cd)2+) The detection limit of (a) is 0.211ug/L and 0.111ug/L respectively.
Example 6
A graphene oxide and polyaniline-modified electrode comprising:
a glassy carbon electrode 1;
the graphene oxide 2 is arranged on the outer surface of the glassy carbon electrode;
a polyaniline layer 3 disposed on the outer surface of the graphene oxide;
and the Nafion layer 4 is arranged on the outer surface of the polyaniline layer.
Example 7
A graphene oxide and polyaniline modified electrochemical sensor, wherein the electrode sensor is an electrolytic cell, and the electrolytic cell comprises: working electrode, auxiliary electrode, reference electrode, electrolyte that sets up in electrolytic bath and bottom.
The working electrode is a graphene oxide and polyaniline modified electrode, and comprises:
a glassy carbon electrode 1;
the graphene oxide 2 is arranged on the outer surface of the glassy carbon electrode;
a polyaniline layer 3 disposed on the outer surface of the graphene oxide;
and the Nafion layer 4 is arranged on the outer surface of the polyaniline layer.
Example 8
A graphene oxide and polyaniline modified electrochemical sensor, wherein the electrode sensor is an electrolytic cell, and the electrolytic cell comprises: working electrode, auxiliary electrode, reference electrode, electrolyte that sets up in electrolytic bath and bottom.
The working electrode is a graphene oxide and polyaniline modified electrode, and comprises:
a glassy carbon electrode 1;
the graphene oxide 2 is arranged on the outer surface of the glassy carbon electrode;
a polyaniline layer 3 disposed on the outer surface of the graphene oxide;
and the Nafion layer 4 is arranged on the outer surface of the polyaniline layer.
The auxiliary electrode is a platinum wire electrode.
Example 9
A graphene oxide and polyaniline modified electrochemical sensor, wherein the electrode sensor is an electrolytic cell, and the electrolytic cell comprises: working electrode, auxiliary electrode, reference electrode, electrolyte that sets up in electrolytic bath and bottom.
The working electrode is a graphene oxide and polyaniline modified electrode, and comprises:
a glassy carbon electrode 1;
the graphene oxide 2 is arranged on the outer surface of the glassy carbon electrode;
a polyaniline layer 3 disposed on the outer surface of the graphene oxide;
and the Nafion layer 4 is arranged on the outer surface of the polyaniline layer.
The reference electrode is a calomel reference electrode
Example 10
A graphene oxide and polyaniline modified electrochemical sensor, wherein the electrode sensor is an electrolytic cell, and the electrolytic cell comprises: working electrode, auxiliary electrode, reference electrode, electrolyte that sets up in electrolytic bath and bottom.
The working electrode is a graphene oxide and polyaniline modified electrode, and comprises:
a glassy carbon electrode 1;
the graphene oxide 2 is arranged on the outer surface of the glassy carbon electrode;
a polyaniline layer 3 disposed on the outer surface of the graphene oxide;
and the Nafion layer 4 is arranged on the outer surface of the polyaniline layer.
And a magnetic stirrer is also arranged in the electrolytic cell.
Comparative example 1
The preparation method and the detection method are the same as example 1, except that the Nafion solution does not contain polyaniline. The results show that: the catalytic signal is unstable.
Comparative example 2
The preparation method is the same as example 1, except that acetate buffer solution with pH of 4.5 is used as electrolyte in the detection process. The results show that: for lead ion (Pb)2+) And cadmium ion (Cd)2+) The detection limit of (A) reaches 0.198ug/L and 0.98ug/L respectively.
Comparative example 3
0.05M ammonium chloride-ammonia (NH) was prepared4Cl-NH3) Buffering a solution, and then preparing a 0.25mg/mL Graphene Oxide (GO) solution by using the buffer solution; and performing electrochemical reduction and deposition in the mixed solution by using a current-time curve method, wherein the deposition potential is-1.3V, and the deposition time is 400s, so that the nitrogen-doped graphene (NG) film is directly formed on the surface of a Glassy Carbon Electrode (GCE).
The detection method was the same as in example 1.
The results show that: lower limit of detection Hg2+0.1. mu. mol/L, Cu2+0.007. mu. mol/L of Pb2+And Cd2+All are 0.008 mu mol/L.
It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and the present invention is not limited thereto, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications and equivalents can be made in the technical solutions described in the foregoing embodiments, or equivalents thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention. Although the present invention has been described with reference to the specific embodiments thereof, it should be understood by those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
Claims (1)
1. An electrochemical detection method for selectively detecting trace heavy metal ions of lead and cadmium in a water body by adopting graphene oxide and a polyaniline modified electrode is characterized by comprising the following steps:
respectively measuring heavy metal ions in a water body by using graphene oxide and a polyaniline modified electrode GO-PAN-Nafion/GCE as working electrodes and adopting an anodic stripping voltammetry;
the detection parameters of the anodic stripping voltammetry are as follows:
the electro-deposition potential is-1.4V, and the electro-deposition time is 180 s;
the static potential is-1.35V, and the static time is 10 s;
the scanning speed is 5mV/s, and the scanning range is-1.4V to-1.35V;
in the detection process of the anodic stripping voltammetry, the electrolyte contains 0.1M acetate and 500 mu gL-1PAN；
The preparation method of the graphene oxide and polyaniline modified electrode GO-PAN-Nafion/GCE comprises the following steps: ultrasonically dispersing graphene oxide in a mixed solution of Polyaniline (PAN) and Nafion to obtain GO-PAN-Nafion turbid liquid; uniformly coating the GO-PAN-Nafion suspension on the surface of the glassy carbon electrode after polishing, cleaning and blow-drying treatment to obtain GO-PAN-Nafion/GCE;
wherein in the GO-PAN-Nafion turbid liquid, the graphene oxide: polyaniline: the mass ratio of Nafion is as follows: 4-5: 1-2: 1 in a book103～2×103；
The concentration of the polyaniline in the polyaniline and Nafion mixed solution is 0.5-1.0 mgL-1The mass fraction of Nafion is 0.5-1.0%.
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