CN103983681B - A kind of for electrochemical sensor detecting heavy metal and its preparation method and application - Google Patents
A kind of for electrochemical sensor detecting heavy metal and its preparation method and application Download PDFInfo
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Abstract
The invention discloses a kind of electrochemical sensor for detecting heavy metal, this sensor includes a glass-carbon electrode being used as working electrode in three-electrode system, the test side finishing ordered mesopore carbon of glass-carbon electrode, on ordered mesopore carbon, deposition has polyaniline and 2-mercapto ethane sulfonic acid sodium.Its preparation method comprises the following steps: first mesoporous carbon disperseed in organic solvent, then drips to glassy carbon electrode surface, then on its surface by electrochemical cyclic voltammetry deposition polyaniline and 2-mercapto ethane sulfonic acid sodium, prepares electrochemical sensor.Its applying step is be placed in solution to be measured by the glass-carbon electrode reactive end of electrochemical sensor, then accesses the electrolyzer of three-electrode system, utilizes DPASV differential pulse anodic stripping voltammetry to complete the detection of concentration of heavy metal ion.Cost of the present invention is low, makes simple, and highly sensitive, Monitoring lower-cut is low, and anti-interference is relatively strong, and application operating is easy, environmentally safe pollution-free.
Description
Technical field
The present invention relates to sensor field, particularly relate to a kind of for electrochemical sensor detecting heavy metal and its preparation method and application, further, relate to a kind of electrochemical sensor for cadmium and plumbous detection and its preparation method and application.
Background technology
Along with the development of industry and society, increasing heavy metal enters in the living environment of people by all means.In these heavy metals, cadmium and lead are especially paid attention to.There are some researches show cadmium and plumbous to the infringement of many organism unsoundnesses, also can destroy ecosystem.In the drinking water of world health organisation recommendations, the most high-load limit value of cadmium is 3 μ gL-1, plumbous most high-load limit value is 10 μ gL-1.At present, micro heavy main measuring methods there are atomic absorption spectrography (AAS), atomic fluorescence spectrometry, inductively coupled plasma mass spectrometry etc..But these methods all exist apparatus expensive, complicated operation, detecting consuming time longer, detection limit is low not, can not the defect such as on-line monitoring, limit their extensive use.On the other hand, Electrochemical Stripping is analyzed method application in micro heavy detects and is increasingly obtained the attention of people, and it has higher sensitivity and reliability, and operational approach is also very simple.
Chemically modified electrode is to carry out MOLECULE DESIGN by the method for chemical modification at electrode surface, by having the molecule of excellent chemical character, ion, polymer are fixed on electrode surface, make certain micro structure, give electrode certain specific chemistry and electrochemical properties, so that height optionally carries out desired reaction, there is in improving selectivity and sensitivity the superiority of uniqueness.Chemically modified electrode has been applied to the detection to multiple environmental and biological samples, meanwhile, analyzes method in conjunction with chemically modified electrode and Electrochemical Stripping and can also obtain good effect for heavy metal analysis.
Summary of the invention
Present invention solves the technical problem that it is overcome the deficiencies in the prior art, it is provided that a kind of with low cost, make the electrochemical sensor based on modified electrode simple, easy to detect, that precision and efficiency of detecting is high.The preparation method correspondingly providing a kind of electrochemical sensor, well in conjunction with the superperformance of mesoporous carbon and sulfhydrylation polyaniline；On this basis, also provide for the application of a kind of above-mentioned electrochemical sensor, this application can with low cost, simplify operation, quickly response, high measurement accuracy and relatively the feature such as common-path interference, stability and repeatability realize the detection to Trace Cadmium and lead.
For solving above-mentioned technical problem, the invention provides a kind of electrochemical sensor for detecting heavy metal, including a glass-carbon electrode being used as working electrode in three-electrode system, the test side finishing ordered mesopore carbon of aforementioned glass-carbon electrode, ordered mesopore carbon deposits polyaniline and 2-mercapto ethane sulfonic acid sodium.
Same technology as the present invention is conceived, and the preparation method that present invention also offers a kind of aforesaid electrochemical sensor comprises the following steps:
S1, modification ordered mesopore carbon: be distributed in organic solvent by ordered mesopore carbon and make suspension, the surface, test side that hanging drop is coated onto glass-carbon electrode obtains the glass-carbon electrode that ordered mesopore carbon is modified；
S2, deposition polyaniline: adopt the surface, test side that polyaniline is deposited on the glass-carbon electrode that aforementioned ordered mesopore carbon is modified by cyclic voltammetry to obtain the glass-carbon electrode that polyaniline/ordered mesopore carbon is modified；
S3, deposition 2-mercapto ethane sulfonic acid sodium: the surface, test side of the glass-carbon electrode that 2-mercapto ethane sulfonic acid sodian deposition is modified by employing cyclic voltammetry at aforementioned polyaniline/ordered mesopore carbon, complete the preparation of electrochemical sensor.
Aforementioned S1 step, particularly as follows: ordered mesopore carbon is made the suspension that concentration is 0.3mg/mL～0.8mg/mL by ultrasonic disperse in DMF solution, takes the aforementioned suspension drop coating of 3 μ L～8 μ L on the surface, test side of glass-carbon electrode.
Aforementioned S2 step, particularly as follows: immersed by the glass-carbon electrode of ordered mesopore carbon modification in the mixed solution one of aniline and sulphuric acid, adopts cyclic voltammetry with rate scanning-0.2V～0.85V scope 2～10 circle of 50mV/s.In this process, occurring polyreaction to form polyaniline between aniline, polyaniline is deposited on the glassy 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 sulphuric acid is 0.05mol/L～0.15mol/L.
Aforementioned S3 step particularly as follows: immerse in the mixed solution two of 2-mercapto ethane sulfonic acid sodium and sulphuric acid by the glass-carbon electrode of polyaniline/ordered mesopore carbon modification, adopt cyclic voltammetry with rate scanning-0.2V～0.85V scope 2～8 circle of 50mV/s, complete the deposition of 2-mercapto ethane sulfonic acid sodium；In aforementioned mixed solution two, 2-mercapto ethane sulfonic acid na concn is 5mM, and the concentration of sulphuric acid is 0.05mol/L～0.15mol/L.
Aforesaid ordered mesopore carbon can be commercially available ordered mesopore carbon, it is also possible to be the ordered mesopore carbon adopting the preparation method comprised the following steps to prepare:
(1) synthesis of silica-base molecular sieve SBA-15: block copolymer P123 is placed in hydrochloric acid and dissolves, then tetraethyl orthosilicate it is added dropwise over, 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 sucking filtration, washing obtain silica-based molecular sieve SBA-15 to neutral, air-dry, roasting；
(2) synthesizing ordered mesoporous carbon: foregoing silicon substrate molecular sieve SBA-15 and water, sucrose, concentrated sulphuric acid are mixed to get mixture; it is dry until mixture becomes black to be placed in by mixture at 100 DEG C～160 DEG C temperature; then it is placed under inert gas shielding by the mixture of black to carry out pyrolysis and obtains thermal decomposition product; remove the SiO 2 molecular sieve template in aforementioned thermal decomposition product by NaOH solution, filter, washing, dry obtain ordered mesopore carbon.
Same technology as the present invention is conceived, and present invention also offers the application in detection heavy metal of electrochemical sensor that a kind of aforesaid electrochemical sensor or aforementioned preparation process prepare, comprises the following steps:
The glass-carbon electrode reactive end of electrochemical sensor is placed in solution to be measured, then access in the electrolyzer 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 glassy carbon electrode surface, then dissolution heavy metal ion again, sets up equation of linear regression according to concentration of heavy metal ion with Stripping Currents change.
Application according to aforementioned electrochemical sensor, the electrochemical sensor of the present invention can be used for the equation of linear regression of the cadmium ion detecting in water body, concentration of cadmium ions and peak current changing value and is:
△ICd(μ A)=0.7073+0.4454CCd(nM)(1)
In formula (1), △ ICdPeak current changing value during for cadmium ion dissolution, unit is μ A；CCdFor the concentration of cadmium ion in solution to be measured, unit is nM；Correlation coefficient is R2=0.9990, Monitoring lower-cut is 0.26nM.
Application according to aforementioned electrochemical sensor, the electrochemical sensor of the present invention can be used for the equation of linear regression of the lead ion detecting in water body, plumbum ion concentration and peak current changing value and is:
△IPb(μ A)=1.7746+0.5707CPb(nM)(2)
In formula (2), △ IPbPeak current changing value during for lead ion dissolution, unit is μ A；CPbFor the concentration of lead ion in solution to be measured, unit is nM；Correlation coefficient is R2=0.9988, Monitoring lower-cut is 0.16nM.
The linear detection range of aforesaid cadmium ion and lead ion is 1～120nM.
In aforementioned applications process, in electrolyzer, electrolyte solution includes 0.1M, and the hac buffer of pH value 3～6, concentration are the bismuth ion solution of 0.5～1.5 μM, and bismuth concentration is preferably 1 μM.
The work process of DPASV differential pulse anodic stripping voltammetry: by the heavy metal ion preenrichment in solution to be measured on the working electrode (s, preenrichment voltage-1.2V, preenrichment time 150s.Preenrichment complete after time of repose 30s, then scanning-1.0V～-0.3V current potential, makes heavy metal ion dissolution from working electrode, the Current-potential curve in record process in leaching.
Differential Pulse Voltammetry parameter: pulse amplitude 0.05V, pulse width 0.2s, pulse period 0.5s.
The innovative point of the present invention is in that:
The invention provides a kind of electrochemical sensor, by at electrochemical sensor glass-carbon electrode reactive end finishing ordered mesopore carbon, sulfhydrylation polyaniline, 2-mercapto ethane sulfonic acid sodium, making electrochemical sensor that cadmium and lead to have the advantages such as highly sensitive, high specificity, good stability.Wherein ordered mesopore carbon has orderly space structure, big specific surface area and superior electron transmission ability, it is provided that good conductive capability and big specific surface area.Polyaniline is deposited on around mesoporous carbon, further increases the specific surface area of glass-carbon electrode reactive end, it is provided that more adsorption site.Last electro-deposition 2-mercapto ethane sulfonic acid sodium so that it is being combined with polyaniline, polyaniline realizes sulfhydrylation, makes the accumulation ability of electrochemical sensor heavy metal be greatly improved.Meanwhile, the sulfonic group on 2-mercapto ethane sulfonic acid sodium 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, enhances the power of test of electrochemical sensor.
Compared with prior art, it is an advantage of the current invention that:
1, the electrochemical sensor of the present invention improves the detection level of electrochemical sensor, maintains 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, it is quick to make, and the electrode obtained has good stability and capacity of resisting disturbance, and the detected representation for micro heavy goes out excellent properties, has higher sensitivity.
3, the electrochemical sensor of the present invention is for detecting while cadmium ion and lead ion, and highly sensitive, Monitoring lower-cut is low, to Ca2+、Mg2+、Cl-、PO4 3-、K+、SO4 2-、Co3+、CO3 2-、Zn2+、Fe3+、Hg2+、Cu2+Strong Deng the capacity of resisting disturbance of interference factor.The electrochemical sensor of the present invention is after storage after a while simultaneously, has remained in that good current-responsive.Compared with tradition heavy metal detection method, have easy and simple to handle, response rapidly, testing cost cheap, detection sensitivity is high, and Monitoring lower-cut is low, anti-interference and the advantage such as stability is excellent.
Except purpose described above, feature and advantage, the present invention also has other purpose, feature and advantage.Below with reference to figure, the present invention is further detailed explanation.
Accompanying drawing explanation
The accompanying drawing constituting the part of the application is used for providing a further understanding of the present invention, and the schematic description and description of the present invention is used for explaining the present invention, is not intended that 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 of the ordered mesopore carbon modification of the present invention.
Fig. 3 is the glass-carbon electrode electron-microscope scanning figure of polyaniline/ordered mesopore carbon modification of the present invention.
Fig. 4 is the glass-carbon electrode electron-microscope scanning figure of 2-mercapto ethane sulfonic acid sodium/polyaniline/ordered mesopore carbon modification of the present invention.
Fig. 5 is the electrochemical sensor of present invention electrochemical impedance collection of illustrative plates of 4 intermediate in manufacturing process.
Fig. 6 be the electrochemical sensor of the present invention in manufacturing process 4 intermediate for cadmium and plumbous current-responsive comparison diagram.
Fig. 7 is that the electrochemical sensor of the present invention is to the cadmium of variable concentrations and the plumbous volt-ampere curve detected and linear regression graph.
Marginal data:
In the accompanying drawings, OMC: ordered mesopore carbon, PANI: polyaniline, MES:2-mercapto ethane sulfonic acid sodium, GCE: glass-carbon electrode, Cd: cadmium ion, Pb: lead ion.
Detailed description of the invention
Below in conjunction with accompanying drawing, embodiments of the invention are described in detail, but the multitude of different ways that the present invention can be defined by the claims and cover is implemented.
Embodiment
The material adopted in following example and instrument are commercially available.Wherein, the full name of block copolymer P123 is poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, and molecular formula is: PEO-PPO-PEO, and trade name is PluronicP123.
Embodiment 1: electrochemical sensor and preparation method thereof
Referring to Fig. 1, a kind of electrochemical sensor, including glass-carbon electrode, glassy carbon electrode surface is modified with one layer of ordered mesopore carbon, has a strata aniline at ordered mesopore carbon substrates, and on polyaniline, electro-deposition has 2-mercapto ethane sulfonic acid sodium again.
The preparation method of aforementioned electrochemical sensor, specifically includes following steps:
1, ordered mesopore carbon is prepared:
(1) synthesis of mesoporous silicon template SBA-15: being placed in hydrochloric acid solution by 8.0g block copolymer P123, (hydrochloric acid solution is by the H of 270g2O and 320mL, 1.54M hydrochloric acid mix formulated) in, in 35 DEG C of water-baths, (bath temperature is 30～35 DEG C all can be implemented) stirring is until block copolymer P123 dissolves, and is then added dropwise over 17g tetraethyl orthosilicate (TEOS) and obtains mixed solution.Being transferred in reactor after mixed solution is stirred 20h at 35 DEG C, at 140 DEG C of temperature, heating in water bath 24h (bath temperature is 140 DEG C～150 DEG C all can be implemented), then carry out sucking filtration and take filtrate.It is dried after filtrate is washed with distilled water to neutrality and obtains white powder.Being put into by white powder in chamber type electric resistance furnace in roasting, controlling heating rate is l DEG C/min, and in 550 DEG C of air, roasting 4h obtains product of roasting.Product of roasting grinds and obtains silica-based molecular sieve SBA-15 powder.
(2) synthesizing ordered mesoporous carbon: take the aforementioned prepared silica-based molecular sieve SBA-15 powder of 1g, separately take 5mL water dissolution sucrose 1.25g and 0.14gH2SO4It is mixed to get mixture with silica-based molecular sieve SBA-15 powder afterwards, mixture is placed in chamber type electric resistance furnace and at 100 DEG C of temperature, keeps 6h, then temperature being increased to 160 DEG C, then be incubated 6h, make the color of mixture become black；Then the mixture of black is carried out under nitrogen air-flow protection in the quartz tube furnace of 900 DEG C pyrolysis, and makes sucrose carbonization, after pyrolysis 6h, obtain thermal decomposition product (thermal decomposition product is carbonized polymers).Thermal decomposition product adds the SiO 2 molecular sieve template that the NaOH solution of 3M is fully removed in thermal decomposition product, then crosses leaching filtering residue, with deionized water wash to neutral, then dry and acquire ordered mesopore carbon.
2, ordered mesopore carbon is modified:
Ordered mesopore carbon ultrasonic disperse is obtained in N,N-dimethylformamide the suspension that order mesoporous concentration of carbon is 0.5mg/mL.Take suspension 5 μ L to 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 is carried out electron-microscope scanning, and Fig. 2 is electron-microscope scanning result.From figure 2 it can be seen that ordered mesopore carbon is bar-shaped ordered structure, average length is 0.8 μm, is completely covered on glassy carbon electrode surface.
3, deposition polyaniline:
The glass-carbon electrode that ordered mesopore carbon is modified is immersed in containing in 0.1M aniline (aniline is through decompression distilation) and the mixed solution one of 0.1M sulphuric acid, adopt cyclic voltammetry to enclose (deposition that scanning 2～8 circle all can realize polyaniline) with the 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 is carried out electron-microscope scanning, and Fig. 3 is electron-microscope scanning result.From figure 3, it can be seen that polyaniline is fully enclosed in around ordered mesopore carbon, increase the specific surface area of modified electrode.
4, deposition 2-mercapto ethane sulfonic acid sodium:
The glass-carbon electrode that polyaniline/ordered mesopore carbon is modified is immersed in the mixed solution two of the 2-mercapto ethane sulfonic acid sodium containing 5mM and 0.1M sulphuric acid, cyclic voltammetry is adopted to enclose (deposition that scanning 2～8 circle all can realize 2-mercapto ethane sulfonic acid sodium) with the rate scanning-0.2V～0.85V scope 4 of 50mV/s, make 2-mercapto ethane sulfonic acid sodian deposition obtain, on the surface, test side of the glass-carbon electrode of polyaniline/ordered mesopore carbon modification, the glass-carbon electrode that 2-mercapto ethane sulfonic acid sodium/polyaniline/ordered mesopore carbon is modified, complete the preparation of electrochemical sensor.
The glass-carbon electrode that 2-mercapto ethane sulfonic acid sodium/polyaniline/ordered mesopore carbon is modified is carried out electron-microscope scanning, and Fig. 4 is electron-microscope scanning result.From fig. 4, it can be seen that 2-mercapto ethane sulfonic acid sodium completely covers modified electrode surface.
In embodiment 1, electrochemical sensor and preparation method thereof is only the preferred embodiments of the present invention mode, take the suspension 3 μ L～8 μ L that concentration is 0.3mg/mL～0.8mg/mL in the present invention to drip in glassy 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 and carries out electro-deposition containing in 0.05mol/L～0.15mol/L aniline (aniline is through decompression distilation) and the mixed solution one of 0.05mol/L～0.15mol/L sulphuric acid, the glass-carbon electrode that polyaniline/ordered mesopore carbon is modified can be obtained equally.
The glass-carbon electrode that polyaniline/ordered mesopore carbon is modified is immersed in the mixed solution two of the 2-mercapto ethane sulfonic acid sodium containing 5mM and 0.05mol/L～0.15mol/L sulphuric acid and carries out electro-deposition, it is possible to obtain the glass-carbon electrode that 2-mercapto ethane sulfonic acid sodium/polyaniline/ordered mesopore carbon is modified.
1, the electrochemical sensor of embodiment 1 is carried out Electrochemical Properties
Glass-carbon electrode (GCE) is characterized respectively by electrochemistry 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-mercapto ethane sulfonic acid sodium/polyaniline/ordered mesopore carbon is modified.Result is as shown in Figure 5.The impedance spectrum semicircle of glass-carbon electrode GCE is very big, and this illustrates that the resistance of GCE is big.After ordered mesopore carbon is modified, nearly straight, illustrate that OMC/GCE conductive capability is fine, resistance is only small.After modifying polyaniline, resistance has almost no change, and PANI/OMC/GCE maintains good conductive ability.Finally modify 2-mercapto ethane sulfonic acid sodium, resistance has to be increased by a small margin, but still than glass-carbon electrode GCE little a lot.On the whole, obtained 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 electrolyte, quickly obtains stable response current.
Above-mentioned electrochemical AC impedance analysis carries out in the 5.0mM potassium ferricyanide solution containing 0.1M potassium chloride.
2, the electrochemical sensor of embodiment 1 is carried out detection performance study
Four intermediate detection performance for cadmium and lead of GCE, OMC/GCE, PANI/OMC/GCE, PANI-MES/OMC/GCE in embodiment 1 preparation process is detected respectively with differential plus Anodic Stripping Voltammetry (DPASV).In DPASV detection process, bismuth ion is enriched on four intermediate, 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 dissolution peak current is according to Bi/GCE, Bi/OMC/GCE, the order of Bi/PANI/OMC/GCE, Bi/PANI-MES/OMC/GCE is gradually increased, it was demonstrated that OMC, the addition of PANI, MES makes the power of test of electrochemical sensor step up.
Above-mentioned differential plus Anodic Stripping Voltammetry analysis is at the cadmium ion (Cd containing 20nM2+) and lead ion (Pb2+), the bismuth ion (Bi of 1 μM3+) 0.1M, pH4.5 acetate buffer solution in 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 reference electrode, platinum electrode is as to electrode, set up three-electrode system, electrolyte solution in three-electrode system electrolyzer is the 0.1M of the bismuth ion containing 1 μM, pH4.5 acetate buffer solution (electrolyte solution can also is that 0.1M, the pH3 containing 0.5～1.5 μM of bismuth ion～6 acetate buffer solutions).Three-electrode system is connected with electrochemical workstation, utilizes DPASV differential pulse anodic stripping voltammetry that the concentration of heavy metal ion in solution to be measured is detected.
The work process of DPASV differential pulse anodic stripping voltammetry: by the heavy metal ion preenrichment in solution to be measured on the working electrode (s, preenrichment voltage-1.2V, preenrichment time 150s.Preenrichment complete after time of repose 30s, then scanning-1.0V～-0.3V current potential, makes heavy metal ion dissolution from working electrode, the Current-potential curve in record process in leaching.
Differential Pulse Voltammetry parameter: pulse amplitude 0.05V, pulse width 0.2s, pulse period 0.5s.
Set up equation of linear regression:
Electrolyzer is put into a magnetic stirring apparatus (magnetic agitation only carries out in the preenrichment stage), is separately added in the cadmium of variable concentrations, lead ion and electrolyte solution, completes the preenrichment of cadmium, lead ion.Electrode stands 30s, measures Current-potential curve with DPASV differential pulse anodic stripping voltammetry.Often having measured a concentration, glass-carbon electrode all loads+0.3V voltage in a blank acetate buffer solution, scans 50s under stirring, removes heavy metal and the bismuth film of electrode surface enrichment completely, is then further continued for measuring next concentration.
Fig. 7 is the Current-potential curve that the cadmium-ion solution of concentration respectively 1nM～120nM is corresponding with the lead ion solution of 1nM～120nM.
As seen from Figure 7, the dissolution voltage of cadmium ion is at-0.83V, and the dissolution voltage of lead ion is at-0.58V.
The equation of linear regression of concentration of cadmium ions and peak current changing value is:
△ICd(μ A)=0.7073+0.4454CCd(nM)(1)
In formula (1), △ ICdPeak current changing value during for cadmium ion dissolution, unit is μ A；CCdFor the concentration value of cadmium ion corresponding in solution to be measured, unit is nM；The correlation coefficient of formula (1) is R2=0.9990, Monitoring lower-cut is 0.26nM.
The equation of linear regression of plumbum ion concentration and peak current changing value is:
△IPb(μ A)=1.7746+0.5707CPb(nM)(2)
In formula (2), △ IPbPeak current changing value during for lead ion dissolution, unit is μ A；CPbFor the concentration value of lead ion corresponding in solution to be measured, unit is nM；The correlation coefficient of formula (2) is R2=0.9988, Monitoring lower-cut is 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 reference electrode, platinum electrode is as to electrode, set up three-electrode system, three-electrode system is connected with electrochemical workstation, in the electrolyte solution of the cadmium ion containing 20nM and the lead ion of 20nM, adds the calcium ion (Ca of 100 times of concentration2+), magnesium ion (Mg2+), chloride ion (Cl-), phosphate anion (PO4 3-), potassium ion (K+), sulfate ion (SO4 2-), the cobalt ion (Co of 50 times of concentration3+), carbanion (CO3 2-), zinc ion (Zn2+), the iron ion (Fe of 10 times of concentration3+), mercury ion (Hg2+), the copper ion (Cu of 5 times of concentration2+), concentration of heavy metal ion each in solution to be measured is detected by the application process with reference to embodiment 2.
Testing result: analyze the electrochemical sensor of embodiment 1 from Current-potential curve only to cadmium, lead ion sensitivity, the calcium ion of 100 times of concentration, magnesium ion, chloride ion, phosphate anion, potassium ion and sulfate ion, the iron ion of the cobalt ion of 50 times of concentration, carbanion and zinc ion and 10 times of concentration and mercury ion disturb 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 again smaller than 5%.Therefore, electrochemical sensor of the present invention has good interference free performance.
2, electrochemical sensor detection stability and repetitive research:
Use the electrochemical sensor of embodiment 1 as working electrode, the cadmium ion of the application process duplicate detection 20nM of reference embodiment 2 and the plumbum ion concentration of 20nM, often detect once, working electrode all loads+0.3V voltage in a blank acetate buffer solution, 50s is scanned under stirring, remove heavy metal and the bismuth film of electrode surface enrichment completely, be then further continued for replication, repeat 5 times.
5 testing results, cadmium ion relative standard deviation is 2.1%, and lead ion relative standard deviation is 2.7%, it was shown that the electrochemical sensor of the present invention has good stability.
3, repetitive research prepared by electrochemical sensor:
According to the method for embodiment 1, making 5 sensors, in same detection environment, the application process with reference to embodiment 2 detects the cadmium ion of 20nM and the lead ion of 20nM, research electrochemical sensor repeatability.
Testing result: cadmium and lead ion relative standard deviation respectively 3.1% and 3.9%, it was shown that the 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 making, equivalent replacement, improvement etc., should be included within protection scope of the present invention.
Claims (9)
1. the preparation method of an electrochemical sensor, it is characterized in that, described electrochemical sensor includes a glass-carbon electrode being used as working electrode in three-electrode system, the test side finishing ordered mesopore carbon of described glass-carbon electrode, on described ordered mesopore carbon, deposition has polyaniline and 2-mercapto ethane sulfonic acid sodium；Its preparation method comprises the following steps:
S1, modification ordered mesopore carbon: be distributed in organic solvent by ordered mesopore carbon and make suspension, the surface, test side that described hanging drop is coated onto glass-carbon electrode obtains the glass-carbon electrode that ordered mesopore carbon is modified；
S2, deposition polyaniline: adopt the surface, test side that polyaniline is deposited on the glass-carbon electrode that described ordered mesopore carbon is modified by cyclic voltammetry to obtain the glass-carbon electrode that polyaniline/ordered mesopore carbon is modified；
S3, deposition 2-mercapto ethane sulfonic acid sodium: the surface, test side of the glass-carbon electrode that 2-mercapto ethane sulfonic acid sodian deposition is modified by employing cyclic voltammetry at described polyaniline/ordered mesopore carbon, complete the preparation of electrochemical sensor.
2. preparation method according to claim 1, it is characterized in that, described S1 step is: by described ordered mesopore carbon by ultrasonic disperse to N, making the suspension that concentration is 0.3mg/mL～0.8mg/mL in dinethylformamide solution, the described hanging drop taking 3 μ L～8 μ L is coated in the surface, test side of glass-carbon electrode.
3. preparation method according to claim 1, it is characterized in that, described S2 step is: the glass-carbon electrode modified by described ordered mesopore carbon immerses in the mixed solution one of aniline and sulphuric acid, adopt cyclic voltammetry with rate scanning-0.2V～0.85V scope 2～10 circle of 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 sulphuric acid is 0.05mol/L～0.15mol/L.
4. preparation method according to claim 1, it is characterized in that, described S3 step is: the glass-carbon electrode modified by described polyaniline/ordered mesopore carbon immerses in the mixed solution two of 2-mercapto ethane sulfonic acid sodium and sulphuric acid, adopt cyclic voltammetry with rate scanning-0.2V～0.85V scope 2～8 circle of 50mV/s, complete the deposition of 2-mercapto ethane sulfonic acid sodium；In described mixed solution two, 2-mercapto ethane sulfonic acid na concn is 5mM, and the concentration of sulphuric acid is 0.05mol/L～0.15mol/L.
5. the preparation method according to any one of Claims 1 to 4, it is characterised in that described ordered mesopore carbon is to adopt the preparation method comprised the following steps to prepare:
(1) synthesis of silica-base molecular sieve SBA-15: block copolymer P123 is placed in hydrochloric acid and dissolves, then tetraethyl orthosilicate it is added dropwise over, 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 sucking filtration, washing obtain silica-based molecular sieve SBA-15 to neutral, air-dry, roasting；
(2) synthesizing ordered mesoporous carbon: described silica-based molecular sieve SBA-15 and water, sucrose, concentrated sulphuric acid are mixed to get mixture; it is dry until mixture becomes black to be placed in by described mixture at 100 DEG C～160 DEG C temperature; then it is placed under inert gas shielding by the mixture of black to carry out pyrolysis and obtains thermal decomposition product; remove the SiO 2 molecular sieve template in described thermal decomposition product by NaOH solution, filter, washing, dry obtain ordered mesopore carbon.
6. the electrochemical sensor that preparation method according to any one of a Claims 1 to 5 prepares application in detection heavy metal, it is characterised in that comprise the following steps:
The glass-carbon electrode reactive end of electrochemical sensor is placed in solution to be measured, then access in the electrolyzer 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 glassy carbon electrode surface, then dissolution heavy metal ion again, sets up equation of linear regression according to concentration of heavy metal ion with Stripping Currents change.
7. application according to claim 6, it is characterised in that described electrochemical sensor is used for detecting the equation of linear regression of cadmium ion, described concentration of cadmium ions and peak current changing value and is:
△ICd(μA)=0.7073+0.4454CCd(nM) (1)
In formula (1), △ ICdPeak current changing value during for cadmium ion dissolution, unit is μ A；CCdFor the concentration of cadmium ion in solution to be measured, unit is nM；Correlation coefficient is R2=0.9990, Monitoring lower-cut is 0.26nM.
8. application according to claim 6, it is characterised in that described electrochemical sensor is used for detecting the equation of linear regression of lead ion, described plumbum ion concentration and peak current changing value and is:
△IPb(μA)=1.7746+0.5707CPb(nM) (2)
In formula (2), △ IPbPeak current changing value during for lead ion dissolution, unit is μ A；CPbFor the concentration of lead ion in solution to be measured, unit is nM；Correlation coefficient is R2=0.9988, Monitoring lower-cut is 0.16nM.
9. the application according to any one in claim 6 to 8, it is characterised in that: in described electrolyzer, electrolyte solution includes the hac buffer of pH value 3～6, concentration is the bismuth ion solution of 0.5～1.5 μM；In described DPASV differential pulse anodic stripping voltammetry, preenrichment voltage is-1.2V, and the preenrichment time is 150s, and sweep limits is-1.0V～-0.3V.
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| CN106018506B (en) * | 2016-05-11 | 2018-10-26 | 中国科学院新疆理化技术研究所 | A method of detecting lead ion using electrochemical sensor |
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