A kind of graphene test paper electrode and its heavy metal detector based on electrochemistry of foundationTechnical field
The utility model is related to detecting instrument technical field more particularly to a kind of graphene test paper electrodes and its base of foundationIn the heavy metal detector of electrochemistry.
Background technology
Due to traditional method in environmental testing in application, equipment, cost, measurement period, sensitivity etc. are firstNature are insufficient, therefore traditional method is extremely limited in the field.Therefore, people will find various methods and goSubstitute and develop traditional chemistry, physics measurement means, electrochemical sensor due to its high sensitivity, short cycle of measurement,The traditional advantage of high reliability etc. and obtain the great concern of people, for decades, become in environmental testingInterior research hotspot simultaneously has been widely used.Currently used detection of heavy metal ion method has atomic emission spectrometry（AES）, atomic absorption spectrography (AAS)（AAS）, inductive coupling plasma-Mass Spectrometry（ICP-MS）Deng.But these methodsDue to complicated for operation, expensive equipment, inconvenient to carry etc., it is difficult to realize field monitoring.Electroanalytical Chemistry is as analysis handSection combines closely the phenomenon that chemical change and electricity, the basic principle of Applied Electrochemistry and experimental technique research substanceComposition, the component content method for analyzing test substances is various, is widely used, technically makes rapid progress, constantly deep in theoryEnter, improve and advance.In scientific research and practical application, electrochemical method is not only an analysis method, and is also oneThe essential tool of kind research, uses electrochemical sensor instrument simple, is a kind of generally acknowledged convenient for being automated with computer interconnectionIt is quick, sensitive, accurately micro and trace analysis methods, as long as usually a few minutes can survey a sample, data are automaticPreserve, can under complex environment live on-line checking, the concentration for measuring metal ion can be down to 10-12 mol/L.Therefore it grindsSystem develops a set of novel heavy metal detecting instrument based on electro-chemical test principle, realizes contents of many kinds of heavy metal ion in Complex water bodyIncluding lead（Pd2+）, cadmium（Cd2+）, copper（Cu2+）Quickly, sensitive, accurate live on-line checking, it is imperative.
Utility model content
The purpose of this utility model provides the inspection of the heavy metal based on electrochemistry of a kind of graphene test paper electrode and its foundationInstrument is surveyed, can realize and lead is included to contents of many kinds of heavy metal ion（Pd2+）, cadmium（Cd2+）, copper（Cu2+）Quickly, it is sensitive, accurateDetection.
First, the utility model provides a kind of graphene test paper electrode, to replace the columnar electrode of present routine, technologyScheme is：Described graphene printing paper electrode includes PET base and the working electrode printed thereon by printing technology, rightElectrode, reference electrode, silver conductive baseline and insulating layer；The working electrode is printing graphene, and described is print to electrodeBrush carbon, the reference electrode are printing silver/silver chlorate；The working electrode is located at PET base center, described to electrode, referenceElectrode is respectively separated to be not in contact with each other positioned at the periphery of working electrode and three, the working electrode, to electrode and reference electrodeExternal silver conductive baseline respectively；The insulating layer is enclosed in the periphery to electrode, reference electrode and makes its internal formation workRegion；The insulating layer simultaneously covers the silver conductive baseline, and the silver conductive baseline extends outward insulationLayer forms contact jaw.
Further, the working electrode is circle, described respectively arc-shaped to electrode, reference electrode.
Further, the working electrode surface deposition has one layer of bismuth film.The toxicity of bismuth metal is extremely low, it is considered to be a kind ofEnvironmentally protective metal.Research shows that bismuth metal has the electroanalysis performance similar with mercury, can be formed with many heavy metal ionSimilar to the binary or multicomponent alloy of amalgam.In terms of heavy metal analysis, bismuth pole is low, electric with overpotential height, background currentPosition window is wide, dissolution peak separator well, the advantages that stability is good, surface easily updates.In addition, bismuth pole is insensitive to dissolved oxygen, thereforeIt can be analyzed under conditions of not deoxygenation, enormously simplify operation complexity, had in terms of heavy metal ion super sensitivity detection wideGeneral application prospect.
Then, the utility model provides a kind of heavy metal detector based on electrochemistry, including electrochemical detection system withAnd its three-electrode electrochemical sensor of input terminal connection, the three-electrode electrochemical sensor are printed using above-mentioned graphenePaper electrode.
Further, the electrochemical detection system is electrochemical workstation.
Further, the electrochemical detection system includes：
Power supply circuit, for powering to each circuit in system；
Control circuit for the operation of circuit each in control system, receives electrochemical signals and handles；
I/V conversion circuits, for the current signal that three-electrode electrochemical sensor generates to be converted into voltage signal；
Filter circuit, for removing the interference signal in transformed voltage signal；
Amplifying circuit, for being amplified to voltage signal；
A/D convertor circuit, for voltage signal to be converted into digital signal by analog signal；
Bipolarity generation circuit, for generating the circuit of positive and negative bipolar voltage,
Potentiostatic circuit, the potential for keeping three-electrode electrochemical sensor working electrode are maintained at steady state value；
Serial ports output circuit for exporting printing function by serial ports, will collect data and be depicted as curve by processing；
Display circuit shows collected signal for passing through liquid crystal display；
The bipolarity generation circuit, A/D convertor circuit, serial ports output circuit and display circuit respectively with the controlCircuit connects, and the potentiostatic circuit is connect with bipolarity generation circuit, the I/V conversion circuits, filter circuit, amplifying circuitIt is connect successively with A/D convertor circuit；The potentiostatic circuit, I/V conversion circuits are connect with three-electrode electrochemical sensor；InstituteState control circuit, I/V conversion circuits, filter circuit, amplifying circuit, A/D convertor circuit, bipolarity generation circuit, constant potential electricityRoad, serial ports output circuit and display circuit are connect with power supply circuit.
Further, the bipolarity generation circuit can be programmed to generate the voltage signal of different wave.
Further, the control circuit selection STM32 microcontrollers.
The utility model is using a huge sum of money in graphene printing paper electrode and mating electrochemical analysis system test lake water sampleBelong to the content of ion, 10 retest rate of recovery are less than 5% for 92.5%, RSD, the testing time<15 minutes；Detection limit<1 µmol/L；Relative deviation is compared with atomic absorption method<5%, therefore the graphene paper electrode in the utility model and electrochemical analysisInstrument has higher accuracy and practicability.
Description of the drawings
Fig. 1 is the structure diagram of graphene printing paper electrode；
Fig. 2 is the circuit diagram of electrochemical detection system；
In figure：1st, PET base, 2, working electrode, 3, to electrode, 4, reference electrode, 5, silver conductive baseline, 6, insulationLayer.
Specific embodiment
Embodiment 1
Referring to Fig. 1, a kind of graphene test paper electrode, including PET base 1（Polyester film）And pass through printing technology thereonThe working electrode 2 of printing, to electrode 3, reference electrode 4, silver conductive baseline 5 and insulating layer 6；Working electrode 2 is printing stoneBlack alkene, is printing carbon to electrode 3, and reference electrode 4 is printing silver/silver chlorate；Working electrode 2 is located at 1 center of PET base, to electricityPole 3, reference electrode 4 are respectively separated to be not in contact with each other positioned at the periphery of working electrode and three, working electrode 2, to electrode 3 and ginsengDistinguish external silver conductive baseline 5 than electrode 4；Insulating layer 6 is enclosed in the periphery to electrode 3, reference electrode 4 and makes its internal shapeInto working region；Insulating layer 6 simultaneously covers silver conductive baseline 5（Continuous white box represents conductive path in Fig. 1, i.e.,Working electrode 2 under insulating layer uninterruptedly connect electrode 3 and reference electrode 4 with silver conductive baseline respectively）, obstruct silverConductive baseline（Silver paste）With the contact of solution to be measured, prevent silver paste exposure from aoxidizing to influence chemical property in air；SilverMatter conduction baseline 5 extends outward insulating layer 6 and forms contact jaw.
Embodiment 2
Referring to Fig. 1, a kind of graphene test paper electrode, on the basis of 1 structure of embodiment, in order to improve in trace metalSensitivity and reproducibility in analysis measurement；Using（Electricity）Chemical deposition prints graphene surface modification counterweight in working electrodeMetal ion has the bismuth film of special electro-chemical activity.
Embodiment 3
Referring to Fig. 2, a kind of heavy metal detector based on electrochemistry connects including electrochemical detection system and its input terminalThe three-electrode electrochemical sensor connect, three-electrode electrochemical sensor use the graphene printing paper electrode in embodiment 2.ElectrificationIt learns detecting system and existing electrochemical workstation may be used, the present embodiment uses following miniature electrochemical analyser, for surveyingThe micro current signal of three electrode sensors generation is measured, including：
Power supply circuit, for powering to each circuit in system；
Control circuit for the operation of circuit each in control system, receives electrochemical signals and handles；Control circuit canTo select STM32 microcontrollers；
I/V conversion circuits, for the current signal that three-electrode electrochemical sensor generates to be converted into voltage signal；I.e. threeThe signal that electrode sensor generates needs that current signal first is converted into the method that voltage signal measures again for micro current signalTo test the size of electric current；
Filter circuit, for removing the interference signal in transformed voltage signal；I.e. due to integrated circuit imperfectionAnd the influence of the factors such as thermal noise of resistance, transformed voltage signal can be made to generate additional interference, if the interference signal is notIt filters out and directly amplifies, it is possible to flood useful signal, it is therefore necessary to be filtered before signal is amplified.
Amplifying circuit, for being amplified to voltage signal；Voltage signal i.e. by I/V conversions is faint voltage letterNumber, sampling is directly carried out to tiny signal and on the one hand requires the resolving power of sampling AD high, on the other hand external circuit is resistedInterference requirement is higher.Therefore selection carries out voltage amplification before being AD converted, and improves the precision of sampling.
A/D convertor circuit, for voltage signal to be converted into digital signal by analog signal；
Bipolarity generation circuit, for generating the circuit of positive and negative bipolar voltage；That is the potential of electrode, which needs, just to be hadIt is negative, it is therefore desirable to which that a circuit that can generate positive and negative bipolar voltage, the circuit can be programmed to generate differentThe voltage signal of waveform.
Potentiostatic circuit, the potential for keeping three-electrode electrochemical sensor working electrode are maintained at steady state value；ExistDuring working sensor, due to the influence of polarization, the offset of electrode potential can be led to, so as to cause the output of sensorIt is unstable, it is therefore desirable to the potential of working electrode be kept to be maintained at steady state value.
Serial ports output circuit for exporting printing function by serial ports, will collect data and be depicted as curve by processing；That is the effect of the partial circuit is to export printing function by serial ports, will collect data and is depicted as curve by processing, so as toJudge the performance of instrument.
Display circuit shows collected signal for passing through liquid crystal display；
Bipolarity generation circuit, A/D convertor circuit, serial ports output circuit and display circuit are connect respectively with control circuit,Potentiostatic circuit is connect with bipolarity generation circuit, I/V conversion circuits, filter circuit, amplifying circuit successively with A/D convertor circuitConnection；Potentiostatic circuit, I/V conversion circuits are connect with three-electrode electrochemical sensor；Control circuit, I/V conversion circuits, filterWave circuit, amplifying circuit, A/D convertor circuit, bipolarity generation circuit, potentiostatic circuit, serial ports output circuit and display circuitIt is connect with power supply circuit.
This heavy metal detector uses anodic stripping voltammetry（Anodic Stripping Voltammetry, ASV）InspectionCheck weighing metal ion, such as differential pulse ASV and square-wave pulse SWASV.
ASV technologies are the electrochemistry of a kind of heavy metal ion invented by Jaroslav Heyrovsky the 1920sAnalysis method.It is simple with high sensitivity, apparatus, it is easy to accomplish the advantages that automation is concerned by people.In factWith novel person Jaroslav Heyrovsky because the outstanding contributions in terms of detection of heavy metal ion obtain the Nuo Bei of nineteen fifty-nineYou encourage at chemistry.
The working mechanism of ASV methods is first to be enriched to heavy metal ion to be measured on working electrode, then make current potential byNegative sense is just scanned, and the heavy metal ion is made to be dissolved out from electrode, records the Current-potential curve of the process in leaching.CertainIn the range of, the peak height of Current-potential curve and the concentration of heavy metal ion heavy metal ion in a linear relationship and different existThere is different spike potentials in identical electrolyte.So dissolution peak current and spike potential can be used as and qualitatively and quantitatively analyzeThe basis of concentration of heavy metal ion.Up to the present, ASV methods can measure 40 kinds or more of heavy metal element, it can be fastMicro heavy metal ion in speed detection sample, and detection sensitivity is very high.Since ASV methods have required instrument and equipment letterThe advantages that single, easy to operate.So very extensive application is obtained in the analysis of ultrapure material and environmental monitoring and analysis.
Heavy metal ion includes electrolysis enrichment and electrolysis two processes of dissolution in ASV detection water.The first step is enrichment process,It, should in solution when the potential of electrode is more than the evolution or deposition potential of certain heavy metal ion by reduction potential plus on the working electrode (sMetal ion species will be reduced to metal and be electroplated on the surface of working electrode, when reduction potential application obtains on the working electrode (sBetween longer metal being plated on electrode surface restored it is more.Second step is then electrolysis process in leaching, when enoughWhen metal layer is plated on working electrode surface, potential is increased to working electrode with constant speed, which will on the working electrode (sDissolution（Aoxidize）.The type of metal can be identified according to the position of oxidation potential, and the difference of oxidation potential can be passed throughIt is carried out at the same time the detection of contents of many kinds of heavy metal ion.Pass through calculating current peak height or peak area and the standard solution ratio under the same termsTo calculating the concentration of heavy metal ion in sample.
Graphene printing paper electrode is connect by this heavy metal detector with miniature electrochemical analyser first, in order to ensure electricityPole and work station are fully connected and errorless, after line connects, survey the corresponding resistance in conducting wire both ends respectively using electronic multimeter,See that resistance value is no within zone of reasonableness.
Using heavy metal ion in homemade graphene paper electrode and mating miniature electrochemical analyser test lake water sampleContent, the results are shown in table below, and 10 retest rate of recovery are less than 5% for 92.5%, RSD, it was demonstrated that the stone of this Project-developingBlack alkene paper electrode and electrochemical analyser have higher accuracy and practicability.
| Analytes | Added (nM) | Found (nM) | Recovery (%) | R.S.D(%) |
| Cd2+ | 0 | Ndb | - | - |
| 500 | 489 | 97.8 | 4.52 |
| 1000 | 925 | 92.5 | 3.66 |
| 10000 | 10330 | 103.3 | 2.73 |
| Pb2+ | 0 | Ndb | - | - |
| 500 | 525 | 105 | 3.52 |
| 1000 | 958 | 95.8 | 2.11 |
| 10000 | 98340 | 98.3 | 2.85 |
| Cu2+ | 0 | 50 | - | 1.92 |
| 500 | 568 | 103.2 | 3.14 |
| 1000 | 1020 | 97.1 | 3.57 |
| 10000 | 10108 | 96.2 | 3.88 |
The above, is only the exemplary embodiments of the utility model, and those skilled in the art explains possibly also with above-mentionedEquivalent technical solution is changed or be revised as to the technical solution stated to the present invention.Therefore, according to the utility modelAny simple modification or substitute equivalents that technical solution is carried out, belong to the greatest extent the scope of protection of present invention.