CN103983681A - Electrochemical sensor for detecting heavy metals and preparation method and application thereof - Google Patents
Electrochemical sensor for detecting heavy metals and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses an electrochemical sensor for detecting heavy metals. The sensor comprises a glassy carbon electrode serving as a working electrode in a three-electrode system, wherein ordered mesoporous carbon is modified on the surface of the detection end of the glassy carbon electrode; polyaniline and 2-mercaptoethanesulfonate are deposited on the ordered mesoporous carbon. A preparation method comprises the following steps of dispersing the mesoporous carbon into an organic solvent to obtain a mixture, then dispensing the mixture onto the surface of the glassy carbon electrode, and depositing polyaniline and 2-mercaptoethanesulfonate on the surface by an electrochemical cyclic voltammetry to prepare the electrochemical sensor. An application step comprises the following steps: putting the reaction end of the glassy carbon electrode of the electrochemical sensor into a solution to be measured, then connecting to an electrolytic basin of the three-electrode system, and implementing the detection on the concentration of heavy metal ions by a differential pulse anodic stripping voltammetry. The electrochemical sensor for detecting the heavy metals is low in cost, easy to manufacture, high in sensitivity, low in detection lower limit, high in interference resistance, easy to apply and operate and safe and pollution-free to the environment.
Description
Technical field
The present invention relates to sensor field, relate in particular to a kind of electrochemical sensor for detection of heavy metal and its preparation method and application, further, relate to a kind of for cadmium and plumbous electrochemical sensor detecting and its preparation method and application.
Background technology
Along with industry and social development, increasing heavy metal enters into people's living environment by all means.In these heavy metals, cadmium and lead are especially paid attention to.There are some researches show cadmium and plumbous to many biosome unsoundness infringements, also can destroy the ecosystem.In the potable water of world health organisation recommendations, the high-load limit value of cadmium is 3 μ gL
-1, plumbous high-load limit value is 10 μ gL
-1.At present, micro heavy main measuring methods is had to atomic absorption spectrography (AAS), atomic fluorescence spectrometry, inductively coupled plasma mass spectrometry etc.But these methods all exist apparatus expensive, complicated operation, detects consuming time longlyer, and detectability is low not, can not on-line monitoring etc. defect, limited their widespread use.On the other hand, the application of Electrochemical Stripping analytical approach in micro heavy detects more and more obtains people's attention, and it has higher sensitivity and reliability, and method of operating is also very simple.
Chemically modified electrode is to carry out MOLECULE DESIGN by the method for chemical modification at electrode surface, molecule, ion, the polymkeric substance with excellent chemical character are fixed on to electrode surface, make certain microstructure, give electrode certain specific chemistry and electrochemical properties, so that high selectivity carry out desired reaction, there is unique superiority improving aspect selectivity and sensitivity.Chemically modified electrode has been applied to the detection to multiple environmental and biological samples, meanwhile, detects and also can obtain good effect for heavy metal in conjunction with chemically modified electrode and Electrochemical Stripping analytical approach.
Summary of the invention
The technical matters that the present invention solves is to overcome the deficiencies in the prior art, provide a kind of with low cost, make the electrochemical sensor based on modified electrode simple, easy to detect, precision and efficiency of detecting is high.The also corresponding preparation method that a kind of electrochemical sensor is provided, the good superperformance in conjunction with mesoporous carbon and sulfhydrylation polyaniline; On this basis, also provide a kind of application of above-mentioned electrochemical sensor, this application can be with low cost, simplify the operation, response fast, high measurement accuracy and realize Trace Cadmium and plumbous detection compared with features such as strong anti-interference, stability and repeatability.
For solving the problems of the technologies described above, the invention provides a kind of electrochemical sensor for detection of heavy metal, comprise that one is used as the glass-carbon electrode of working electrode in three-electrode system, the test side finishing ordered mesopore carbon of aforementioned glass-carbon electrode, deposits polyaniline and 2-ethane thiol sodium sulfonate on ordered mesopore carbon.
As same technical conceive of the present invention, the present invention also provides a kind of preparation method of aforesaid electrochemical sensor, comprises the following steps:
S1, modification ordered mesopore carbon: ordered mesopore carbon is distributed in organic solvent and makes suspending liquid, and the surface, test side that hanging drop is coated onto to glass-carbon electrode obtains the glass-carbon electrode that ordered mesopore carbon is modified;
S2, deposition polyaniline: the surface, test side that adopts cyclic voltammetry that polyaniline is deposited on to the glass-carbon electrode of aforementioned ordered mesopore carbon modification obtains the glass-carbon electrode that polyaniline/ordered mesopore carbon is modified;
S3, deposition 2-ethane thiol sodium sulfonate: adopt cyclic voltammetry 2-ethane thiol sodium sulfonate to be deposited on to the surface, test side of the glass-carbon electrode of aforementioned polyaniline/ordered mesopore carbon modification, complete the preparation of electrochemical sensor.
Aforementioned S1 step is specially: ordered mesopore carbon is made to the suspending liquid that concentration is 0.3mg/mL～0.8mg/mL by ultrasonic being distributed in DMF solution, and the aforementioned hanging drop of getting 3 μ L～8 μ L is coated in the surface, test side of glass-carbon electrode.
Aforementioned S2 step is specially: the glass-carbon electrode that ordered mesopore carbon is modified immerses in the mixed solution one of aniline and sulfuric acid, adopts rate scanning-0.2V～0.85V scope 2～10 circles of cyclic voltammetry with 50mV/s.In this process, between aniline, polymerization reaction take place forms polyaniline, and polyaniline is deposited on the glass-carbon electrode surface that ordered mesopore carbon is modified, and completes polyaniline deposition step; In aforementioned mixed solution one, the concentration of aniline is 0.05mol/L～0.15mol/L, and the concentration of sulfuric acid is 0.05mol/L～0.15mol/L.
Aforementioned S3 step is specially: the glass-carbon electrode that polyaniline/ordered mesopore carbon is modified immerses in the mixed solution two of 2-ethane thiol sodium sulfonate and sulfuric acid, adopt rate scanning-0.2V～0.85V scope 2～8 circles of cyclic voltammetry with 50mV/s, complete the deposition of 2-ethane thiol sodium sulfonate; In aforementioned mixed solution two, 2-ethane thiol sodium sulfonate concentration is 5mM, and the concentration of sulfuric acid is 0.05mol/L～0.15mol/L.
Aforesaid ordered mesopore carbon can be commercially available ordered mesopore carbon, can also be the ordered mesopore carbon that adopts the preparation method who comprises the following steps to prepare:
(1) synthesis of silica-base molecular sieve SBA-15: segmented copolymer P123 is placed in to hydrochloric acid and dissolves, then dropwise add ethyl orthosilicate, after stirring, in 30 DEG C～35 DEG C water-baths, heating obtains mixed solution, by the water-bath in 140 DEG C～150 DEG C of aforementioned mixed solution, then suction filtration, washing to neutral, air-dry, roasting obtain silica-based molecular sieve SBA-15;
(2) synthesizing ordered mesoporous carbon: foregoing silicon substrate molecular sieve SBA-15 and water, sucrose, the concentrated sulphuric acid are mixed to get to potpourri; potpourri is placed at 100 DEG C～160 DEG C temperature dry until potpourri becomes black; then the potpourri of black is placed in and under inert gas shielding, carries out pyrolysis and obtain pyrolysis product; by the SiO 2 molecular sieve template in NaOH solution removal aforementioned hot hydrolysis products, filtration, washing, the dry ordered mesopore carbon that obtains.
As same technical conceive of the present invention, the present invention also provides electrochemical sensor that a kind of aforesaid electrochemical sensor or aforementioned preparation method make in the application detecting in heavy metal, comprises the following steps:
The glass-carbon electrode reactive end of electrochemical sensor is placed in to solution to be measured, then access in the electrolytic cell of three-electrode system and carry out Electrochemical Detection as working electrode, utilize DPASV differential pulse anodic stripping voltammetry, first preenrichment heavy metal ion is in glass-carbon electrode surface, and then stripping heavy metal ion, set up equation of linear regression according to concentration of heavy metal ion and Stripping Currents variation.
According to the application of aforementioned electric chemical sensor, electrochemical sensor of the present invention can be used for detecting the cadmium ion in water body, and the equation of linear regression of concentration of cadmium ions and peak current changing value is:
△I
Cd(μA)＝0.7073+0.4454C
Cd(nM) (1)
In formula (1), △ I
cdpeak current changing value during for cadmium ion stripping, unit is μ A; C
cdfor the concentration of cadmium ion in solution to be measured, unit is nM; Related coefficient is R
2=0.9990, under detection, be limited to 0.26nM.
According to the application of aforementioned electric chemical sensor, electrochemical sensor of the present invention can be used for detecting the lead ion in water body, and the equation of linear regression of plumbum ion concentration and peak current changing value is:
△I
Pb(μA)＝1.7746+0.5707C
Pb(nM) (2)
In formula (2), △ I
pbpeak current changing value during for lead ion stripping, unit is μ A; C
pbfor the concentration of lead ion in solution to be measured, unit is nM; Related coefficient is R
2=0.9988, under detection, be limited to 0.16nM.
The linear detection range of aforesaid cadmium ion and lead ion is 1～120nM.
In aforementioned applications process, in electrolytic cell, electrolyte solution comprises 0.1M, and the hac buffer of pH value 3～6, concentration are the bismuth ion solution of 0.5～1.5 μ M, and bismuth ion concentration is preferably 1 μ M.
The course of work of DPASV differential pulse anodic stripping voltammetry: by the heavy metal ion preenrichment in solution to be measured on working electrode, preenrichment voltage-1.2V, preenrichment time 150s.Time of repose 30s after preenrichment completes, then scanning-1.0V～-0.3V current potential, makes heavy metal ion stripping from working electrode, records the Current-potential curve in process in leaching.
Differential Pulse Voltammetry parameter: pulse-response amplitude 0.05V, pulse width 0.2s, recurrence interval 0.5s.
Innovative point of the present invention is:
The invention provides a kind of electrochemical sensor, by at electrochemical sensor glass-carbon electrode reactive end finishing ordered mesopore carbon, sulfhydrylation polyaniline, 2-ethane thiol sodium sulfonate, make electrochemical sensor there is the advantages such as highly sensitive, high specificity, good stability to cadmium and lead.Wherein ordered mesopore carbon has orderly space structure, large specific surface area and superior electronics transmission capacity, and good conductive capability and large specific surface area are provided.Polyaniline is deposited on around mesoporous carbon, has further increased the specific surface area of glass-carbon electrode reactive end, and more adsorption site is provided.Last electro-deposition 2-ethane thiol sodium sulfonate, makes it be combined with polyaniline, and polyaniline is realized sulfhydrylation, and electrochemical sensor is greatly improved to the accumulation ability of heavy metal.Meanwhile, the sulfonic group on 2-ethane thiol sodium sulfonate can pass through Electrostatic Absorption cadmium ion and lead ion, and sulphur atom can be combined with cadmium ion and lead ion coordination, improves electrode response, has strengthened the detectability of electrochemical sensor.
Compared with prior art, the invention has the advantages that:
1, electrochemical sensor of the present invention has improved the detection level of electrochemical sensor, has kept good current-responsive, has good stability, repeatability and reliability of structure.
2, the preparation method of electrochemical sensor provided by the invention, technique is simple, with low cost, making is quick, the electrode obtaining has good stability and antijamming capability, goes out excellent properties, has higher sensitivity for the detected representation of micro heavy.
3, when electrochemical sensor of the present invention is used for cadmium ion and lead ion, detect, highly sensitive, detect lower limit low, to Ca
2+, Mg
2+, Cl
-, PO
4 3-, K
+, SO
4 2-, Co
3+, CO
3 2-, Zn
2+, Fe
3+, Hg
2+, Cu
2+antijamming capability Deng interference factor is strong.Electrochemical sensor of the present invention, after storage after a while, has still kept good current-responsive simultaneously.Compared with traditional heavy metal detection method, have easy and simple to handle, the advantage such as response is rapidly, testing cost is cheap, and detection sensitivity is high, detects lower limit low, and anti-interference and stability are good.
Except object described above, feature and advantage, the present invention also has other object, feature and advantage.Below with reference to figure, the present invention is further detailed explanation.
Brief description of the drawings
The accompanying drawing that forms the application's a part is used to provide a further understanding of the present invention, and schematic description and description of the present invention is used for explaining the present invention, does not form inappropriate limitation of the present invention.
Fig. 1 is structure and the preparation process figure of electrochemical sensor of the present invention.
Fig. 2 is the glass-carbon electrode electron-microscope scanning figure that ordered mesopore carbon of the present invention is modified.
Fig. 3 is the glass-carbon electrode electron-microscope scanning figure that polyaniline of the present invention/ordered mesopore carbon is modified.
Fig. 4 is the glass-carbon electrode electron-microscope scanning figure that 2-ethane thiol sodium sulfonate/polyaniline of the present invention/ordered mesopore carbon is modified.
Fig. 5 is the electrochemical impedance collection of illustrative plates of electrochemical sensor of the present invention 4 intermediates in manufacturing process.
Fig. 6 be electrochemical sensor of the present invention in manufacturing process 4 intermediates for cadmium and plumbous current-responsive comparison diagram.
Fig. 7 is that electrochemical sensor of the present invention is to the cadmium of variable concentrations and plumbous volt-ampere curve and the linear regression graph detecting.
Marginal data:
In the accompanying drawings, OMC: ordered mesopore carbon, PANI: polyaniline, MES:2-ethane thiol sodium sulfonate, GCE: glass-carbon electrode, Cd: cadmium ion, Pb: lead ion.
Embodiment
Below in conjunction with accompanying drawing, embodiments of the invention are elaborated, but the multitude of different ways that the present invention can be defined by the claims and cover is implemented.
Embodiment
The material adopting in following examples and instrument are commercially available.Wherein, the full name of segmented copolymer P123 is polyethylene oxide-polypropyleneoxide-polyethylene oxide triblock copolymer, and molecular formula is: PEO-PPO-PEO, trade name is Pluronic P123.
Embodiment 1: electrochemical sensor and preparation method thereof
Referring to Fig. 1, a kind of electrochemical sensor, comprises glass-carbon electrode, and glass-carbon electrode finishing has one deck ordered mesopore carbon, has one deck polyaniline at ordered mesopore carbon substrates, and on polyaniline, electro-deposition has 2-ethane thiol sodium sulfonate again.
The preparation method of aforementioned electric chemical sensor, specifically comprises the following steps:
1, prepare ordered mesopore carbon:
(1) mesoporous silicon template SBA-15's is synthetic: 8.0g segmented copolymer P123 is placed in to hydrochloric acid solution, and (hydrochloric acid solution is by the H of 270g
2the hydrochloric acid of O and 320mL, 1.54M is mixed formulated) in, in 35 DEG C of water-baths, (bath temperature is 30～35 DEG C all can be implemented) stirs until segmented copolymer P123 dissolves, and then dropwise adds 17g ethyl orthosilicate (TEOS) to obtain mixed solution.After mixed solution is stirred to 20h at 35 DEG C, be transferred in reactor, heating water bath 24h at 140 DEG C of temperature (bath temperature is 140 DEG C～150 DEG C all can be implemented), then carries out suction filtration and gets filtrate.Filtrate is washed with distilled water to after neutrality and is dried and obtains white powder.White powder is put into chamber type electric resistance furnace roasting, and controlling heating rate is l DEG C/min, and in 550 DEG C of air, roasting 4h obtains product of roasting.Product of roasting is ground and is obtained silica-based molecular sieve SBA-15 powder.
(2) synthesizing ordered mesoporous carbon: get the aforementioned silica-based molecular sieve SBA-15 powder making of 1g, separately get 5mL water dissolving saccharose 1.25g and 0.14g H
2sO
4be mixed to get potpourri with silica-based molecular sieve SBA-15 powder afterwards, potpourri is placed in to chamber type electric resistance furnace and keeps 6h at 100 DEG C of temperature, then temperature is increased to 160 DEG C, then is incubated 6h, make the color of potpourri become black; Then the potpourri of black is carried out under nitrogen air-flow protection in the quartz tube furnace of 900 DEG C to pyrolysis, and make sucrose carbonization, after pyrolysis 6h, obtain pyrolysis product (pyrolysis product is carbonized polymers).In pyrolysis product, add the NaOH solution of 3M fully to remove the SiO 2 molecular sieve template in pyrolysis product, then cross leaching filter residue,, be then dried and acquire ordered mesopore carbon to neutral with deionized water washing.
2, modify ordered mesopore carbon:
Ultrasonic ordered mesopore carbon being scattered in obtained to the suspending liquid that order mesoporous concentration of carbon is 0.5mg/mL in DMF.Get suspending liquid 5 μ L and drip in glass-carbon electrode (3mm diameter) surface, naturally dry, obtain the glass-carbon electrode that ordered mesopore carbon is modified.
The glass-carbon electrode that ordered mesopore carbon is modified carries out electron-microscope scanning, and Fig. 2 is electron-microscope scanning result.As can be seen from Figure 2, ordered mesopore carbon is bar-shaped ordered structure, and average length is 0.8 μ m, covers glass-carbon electrode surface completely.
3, deposition polyaniline:
The glass-carbon electrode that ordered mesopore carbon is modified is immersed in the mixed solution one containing 0.1M aniline (aniline is purified through decompression distillation) and 0.1M sulfuric acid, adopt cyclic voltammetry to enclose (deposition that scanning 2～8 circles all can be realized polyaniline) with rate scanning-0.2V～0.85V scope 6 of 50mV/s, obtain the glass-carbon electrode that polyaniline/ordered mesopore carbon is modified.
The glass-carbon electrode that polyaniline/ordered mesopore carbon is modified carries out electron-microscope scanning, and Fig. 3 is electron-microscope scanning result.As can be seen from Figure 3, polyaniline is fully enclosed in ordered mesopore carbon around, has increased the specific surface area of modified electrode.
4, deposition 2-ethane thiol sodium sulfonate:
The glass-carbon electrode that polyaniline/ordered mesopore carbon is modified is immersed in containing in the 2-ethane thiol sodium sulfonate of 5mM and the mixed solution two of 0.1M sulfuric acid, adopt cyclic voltammetry to enclose (deposition that scanning 2～8 circles all can be realized 2-ethane thiol sodium sulfonate) with rate scanning-0.2V～0.85V scope 4 of 50mV/s, the surface, test side that makes 2-ethane thiol sodium sulfonate be deposited on the glass-carbon electrode of polyaniline/ordered mesopore carbon modification obtains the glass-carbon electrode that 2-ethane thiol sodium sulfonate/polyaniline/ordered mesopore carbon is modified, and completes the preparation of electrochemical sensor.
The glass-carbon electrode that 2-ethane thiol sodium sulfonate/polyaniline/ordered mesopore carbon is modified carries out electron-microscope scanning, and Fig. 4 is electron-microscope scanning result.As can be seen from Figure 4,2-ethane thiol sodium sulfonate has covered modified electrode surface completely.
In embodiment 1, electrochemical sensor and preparation method thereof is only the preferred embodiments of the present invention mode, the suspending liquid 3 μ L～8 μ L that get in the present invention concentration and be 0.3mg/mL～0.8mg/mL drip in glass-carbon electrode surface, all can prepare the glass-carbon electrode that ordered mesopore carbon is modified.
The glass-carbon electrode that ordered mesopore carbon is modified is immersed in the mixed solution one containing 0.05mol/L～0.15mol/L aniline (aniline is purified through decompression distillation) and 0.05mol/L～0.15mol/L sulfuric acid and carries out electro-deposition, can obtain equally the glass-carbon electrode that polyaniline/ordered mesopore carbon is modified.
The glass-carbon electrode that polyaniline/ordered mesopore carbon is modified is immersed in containing carrying out electro-deposition in the 2-ethane thiol sodium sulfonate of 5mM and the mixed solution two of 0.05mol/L～0.15mol/L sulfuric acid, can obtain the glass-carbon electrode that 2-ethane thiol sodium sulfonate/polyaniline/ordered mesopore carbon is modified.
1, the electrochemical sensor of embodiment 1 is carried out to Electrochemical Properties
Characterize respectively glass-carbon electrode (GCE) by galvanochemistry ac impedance spectroscopy (EIS) method, the glass-carbon electrode (OMC/GCE) that ordered mesopore carbon is modified, the glass-carbon electrode (PANI/OMC/GCE) that polyaniline/ordered mesopore carbon is modified, the glass-carbon electrode (PANI-MES/OMC/GCE) that 2-ethane thiol sodium sulfonate/polyaniline/ordered mesopore carbon is modified.Result as shown in Figure 5.The impedance spectrum semicircle of glass-carbon electrode GCE is very large, and the resistance of this explanation GCE is large.After ordered mesopore carbon is modified, be close to straight line, illustrate that OMC/GCE conductive capability is fine, resistance is very little.Modify after polyaniline, resistance does not almost change, and PANI/OMC/GCE has kept good conductive ability.Finally modify 2-ethane thiol sodium sulfonate, resistance has by a small margin to be increased, but still little more a lot of than glass-carbon electrode GCE.On the whole, prepared PANI-MES/OMC/GCE has good conductive capability, and the electrochemical sensor of embodiment 1 can significantly improve the transfer velocity of electronics between working electrode and electrolytic solution, obtains fast stable response current.
Above-mentioned electrochemical AC impedance analysis is containing carrying out in the 5.0mM potassium ferricyanide solution of 0.1M potassium chloride.
2, the electrochemical sensor of embodiment 1 is detected to performance study
Detect respectively four intermediates of GCE, OMC/GCE, PANI/OMC/GCE, PANI-MES/OMC/GCE in embodiment 1 preparation process with differentiated pulse stripping voltammetry (DPASV) for cadmium and plumbous detection performance.In DPASV testing process, bismuth ion is enriched on four intermediates, forms Bi/GCE, Bi/OMC/GCE, Bi/PANI/OMC/GCE, Bi/PANI-MES/OMC/GCE.
Referring to Fig. 6, as can be seen from Figure 6 stripping peak current is according to Bi/GCE, Bi/OMC/GCE, Bi/PANI/OMC/GCE, the order of Bi/PANI-MES/OMC/GCE increases gradually, proves OMC, PANI, adding of MES progressively improves the detectability of electrochemical sensor.
The analysis of above-mentioned differentiated pulse stripping voltammetry is the cadmium ion (Cd that is containing 20nM
2+) and lead ion (Pb
2+), the bismuth ion (Bi of 1 μ M
3+) 0.1M, in pH4.5 acetate buffer solution, carry out.
Embodiment 2: the application process of electrochemical sensor
Using the glass-carbon electrode of embodiment 1 as working electrode, using saturated calomel electrode as contrast electrode, platinum electrode is as to electrode, set up three-electrode system, electrolyte solution in three-electrode system electrolytic cell is the 0.1M of the bismuth ion that contains 1 μ M, pH4.5 acetate buffer solution (electrolyte solution can also be the 0.1M that contains 0.5～1.5 μ M bismuth ion, pH3～6 acetate buffer solution).Three-electrode system is connected with electrochemical workstation, utilizes DPASV differential pulse anodic stripping voltammetry to detect the concentration of heavy metal ion in solution to be measured.
The course of work of DPASV differential pulse anodic stripping voltammetry: by the heavy metal ion preenrichment in solution to be measured on working electrode, preenrichment voltage-1.2V, preenrichment time 150s.Time of repose 30s after preenrichment completes, then scanning-1.0V～-0.3V current potential, makes heavy metal ion stripping from working electrode, records the Current-potential curve in process in leaching.
Differential Pulse Voltammetry parameter: pulse-response amplitude 0.05V, pulse width 0.2s, recurrence interval 0.5s.
Set up equation of linear regression:
In electrolytic cell, put into a magnetic stirring apparatus (magnetic agitation is only carried out in the preenrichment stage), add respectively in cadmium, lead ion and the electrolyte solution of variable concentrations, complete the preenrichment of cadmium, lead ion.Electrode leaves standstill 30s, measures Current-potential curve by DPASV differential pulse anodic stripping voltammetry.The complete concentration of every mensuration, glass-carbon electrode is loading+0.3V voltage in a blank acetate buffer solution all, under stirring, scans 50s, removes heavy metal and the bismuth film of electrode surface enrichment completely, and then continue to measure next concentration.
Fig. 7 is that concentration is respectively the cadmium-ion solution of 1nM～120nM and Current-potential curve corresponding to lead ion solution of 1nM～120nM.
As seen from Figure 7, the stripping voltage of cadmium ion is at-0.83V, and the stripping voltage of lead ion is at-0.58V.
The equation of linear regression of concentration of cadmium ions and peak current changing value is:
△I
Cd(μA)＝0.7073+0.4454C
Cd(nM) (1)
In formula (1), △ I
cdpeak current changing value during for cadmium ion stripping, unit is μ A; C
cdfor the concentration value of corresponding cadmium ion in solution to be measured, unit is nM; The related coefficient of formula (1) is R
2=0.9990, under detection, be limited to 0.26nM.
The equation of linear regression of plumbum ion concentration and peak current changing value is:
△I
Pb(μA)＝1.7746+0.5707C
Pb(nM) (2)
In formula (2), △ I
pbpeak current changing value during for lead ion stripping, unit is μ A; C
pbfor the concentration value of corresponding lead ion in solution to be measured, unit is nM; The related coefficient of formula (2) is R
2=0.9988, under detection, be limited to 0.16nM.
1, the anti-interference research of electrochemical sensor:
Using the electrochemical sensor of embodiment 1 as working electrode, saturated calomel electrode is as contrast electrode, platinum electrode is as to electrode, set up three-electrode system, three-electrode system is connected with electrochemical workstation, to the calcium ion (Ca that adds 100 times of concentration in the electrolyte solution containing the cadmium ion of 20nM and the lead ion of 20nM
2+), magnesium ion (Mg
2+), chlorion (Cl
-), phosphate anion (PO
4 3-), potassium ion (K
+), sulfate ion (SO
4 2-), the cobalt ions (Co of 50 times of concentration
3+), carbanion (CO
3 2-), zinc ion (Zn
2+), the ferric ion (Fe of 10 times of concentration
3+), mercury ion (Hg
2+), the copper ion (Cu of 5 times of concentration
2+), with reference to the application process of embodiment 2, each concentration of heavy metal ion in solution to be measured is detected.
Testing result: analyze the electrochemical sensor of embodiment 1 only to cadmium, lead ion sensitivity from Current-potential curve, calcium ion, magnesium ion, chlorion, phosphate anion, potassium ion and the sulfate ion of 100 times of concentration, cobalt ions, carbanion and the zinc ion of 50 times of concentration and the ferric ion of 10 times of concentration and mercury ion disturb and are less than 5% for the peak point current of electrochemical sensor of the present invention.The interference of the copper ion of 5 times of concentration is also less than 5%.Therefore, electrochemical sensor of the present invention has good interference free performance.
2, electrochemical sensor detects stability and repetitive research:
Use the electrochemical sensor of embodiment 1 as working electrode, with reference to the cadmium ion of the application process duplicate detection 20nM of embodiment 2 and the plumbum ion concentration of 20nM, every detection is once complete, working electrode is loading+0.3V voltage in a blank acetate buffer solution all, under stirring, scan 50s, remove heavy metal and the bismuth film of electrode surface enrichment completely, and then continue replication, repeat 5 times.
5 testing results, cadmium ion relative standard deviation is 2.1%, lead ion relative standard deviation is 2.7%, shows that electrochemical sensor of the present invention has good stability.
3, the repetitive research that prepared by electrochemical sensor:
According to the method for embodiment 1, make 5 sensors, in same testing environment, detect the cadmium ion of 20nM and the lead ion of 20nM with reference to the application process of embodiment 2, research electrochemical sensor repeatability.
Testing result: cadmium and lead ion relative standard deviation are respectively 3.1% and 3.9%, shows that electrochemical sensor of the present invention has good repeatability.
The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, to those skilled in the art, the present invention can have various modifications and variations.Within every the spirit and principles in the present invention, any amendment of doing, be equal to replacement, improvement etc., within protection scope of the present invention all should be included in.
Claims (10)
1. the electrochemical sensor for detection of heavy metal, comprise that one is used as the glass-carbon electrode of working electrode in three-electrode system, it is characterized in that the test side finishing ordered mesopore carbon of described glass-carbon electrode deposits polyaniline and 2-ethane thiol sodium sulfonate on described ordered mesopore carbon.
2. a preparation method for electrochemical sensor as claimed in claim 1, is characterized in that, comprises the following steps:
S1, modification ordered mesopore carbon: ordered mesopore carbon is distributed in organic solvent and makes suspending liquid, and the surface, test side that described hanging drop is coated onto to glass-carbon electrode obtains the glass-carbon electrode that ordered mesopore carbon is modified;
S2, deposition polyaniline: the surface, test side that adopts cyclic voltammetry that polyaniline is deposited on to the glass-carbon electrode of described ordered mesopore carbon modification obtains the glass-carbon electrode that polyaniline/ordered mesopore carbon is modified;
S3, deposition 2-ethane thiol sodium sulfonate: adopt cyclic voltammetry 2-ethane thiol sodium sulfonate to be deposited on to the surface, test side of the glass-carbon electrode of described polyaniline/ordered mesopore carbon modification, complete the preparation of electrochemical sensor.
3. preparation method according to claim 2, it is characterized in that: described S1 step is: by described ordered mesopore carbon by the ultrasonic N of being distributed to, in dinethylformamide solution, make the suspending liquid that concentration is 0.3mg/mL～0.8mg/mL, the described hanging drop of getting 3 μ L～8 μ L is coated in the surface, test side of glass-carbon electrode.
4. preparation method according to claim 2, it is characterized in that, described S2 step is: the glass-carbon electrode that described ordered mesopore carbon is modified immerses in the mixed solution one of aniline and sulfuric acid, adopt rate scanning-0.2V～0.85V scope 2～10 circles of cyclic voltammetry with 50mV/s, complete the deposition of polyaniline; In described mixed solution one, the concentration of aniline is 0.05mol/L～0.15mol/L, and the concentration of sulfuric acid is 0.05mol/L～0.15mol/L.
5. preparation method according to claim 2, it is characterized in that, described S3 step is: the glass-carbon electrode that described polyaniline/ordered mesopore carbon is modified immerses in the mixed solution two of 2-ethane thiol sodium sulfonate and sulfuric acid, adopt rate scanning-0.2V～0.85V scope 2～8 circles of cyclic voltammetry with 50mV/s, complete the deposition of 2-ethane thiol sodium sulfonate; In described mixed solution two, 2-ethane thiol sodium sulfonate concentration is 5mM, and the concentration of sulfuric acid is 0.05mol/L～0.15mol/L.
6. according to the preparation method described in any one in claim 2～5, it is characterized in that, described ordered mesopore carbon is to adopt the preparation method who comprises the following steps to prepare:
(1) synthesis of silica-base molecular sieve SBA-15: segmented copolymer P123 is placed in to hydrochloric acid and dissolves, then dropwise add ethyl orthosilicate, after stirring, in 30 DEG C～35 DEG C water-baths, heating obtains mixed solution, by the water-bath in 140 DEG C～150 DEG C of described mixed solution, then suction filtration, washing to neutral, air-dry, roasting obtain silica-based molecular sieve SBA-15;
(2) synthesizing ordered mesoporous carbon: described silica-based molecular sieve SBA-15 and water, sucrose, the concentrated sulphuric acid are mixed to get to potpourri; described potpourri is placed at 100 DEG C～160 DEG C temperature dry until potpourri becomes black; then the potpourri of black is placed in and under inert gas shielding, carries out pyrolysis and obtain pyrolysis product; by the SiO 2 molecular sieve template in pyrolysis product described in NaOH solution removal, filtration, washing, the dry ordered mesopore carbon that obtains.
7. the electrochemical sensor that in electrochemical sensor as claimed in claim 1 or claim 2～6, described in any one, preparation method makes in the application detecting in heavy metal, is characterized in that, comprises the following steps:
The glass-carbon electrode reactive end of electrochemical sensor is placed in to solution to be measured, then access in the electrolytic cell of three-electrode system and carry out Electrochemical Detection as working electrode, utilize DPASV differential pulse anodic stripping voltammetry, first preenrichment heavy metal ion is in glass-carbon electrode surface, and then stripping heavy metal ion, set up equation of linear regression according to concentration of heavy metal ion and Stripping Currents variation.
8. application according to claim 7, is characterized in that, described electrochemical sensor is for detection of cadmium ion, and the equation of linear regression of described concentration of cadmium ions and peak current changing value is:
△I
Cd(μA)＝0.7073+0.4454C
Cd(nM) (1)
In formula (1), △ I
cdpeak current changing value during for cadmium ion stripping, unit is μ A; C
cdfor the concentration of cadmium ion in solution to be measured, unit is nM; Related coefficient is R
2=0.9990, under detection, be limited to 0.26nM.
9. application according to claim 7, is characterized in that, described electrochemical sensor is for detection of lead ion, and the equation of linear regression of described plumbum ion concentration and peak current changing value is:
△I
Pb(μA)＝1.7746+0.5707C
Pb(nM) (2)
In formula (2), △ I
pbpeak current changing value during for lead ion stripping, unit is μ A; C
pbfor the concentration of lead ion in solution to be measured, unit is nM; Related coefficient is R
2=0.9988, under detection, be limited to 0.16nM.
10. according to the application described in any one in claim 7 to 9, it is characterized in that: in described electrolytic cell, electrolyte solution comprises that hac buffer, the concentration of pH value 3～6 are the bismuth ion solution of 0.5～1.5 μ M; In described DPASV differential pulse anodic stripping voltammetry, preenrichment voltage is-1.2V, and the preenrichment time is 150s, and sweep limit is-1.0V～-0.3V.
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