CN110133083A - The electrode face finish material and preparation method and application of a kind of pair of phosphoric acid salt density value - Google Patents
The electrode face finish material and preparation method and application of a kind of pair of phosphoric acid salt density value Download PDFInfo
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- CN110133083A CN110133083A CN201910329021.0A CN201910329021A CN110133083A CN 110133083 A CN110133083 A CN 110133083A CN 201910329021 A CN201910329021 A CN 201910329021A CN 110133083 A CN110133083 A CN 110133083A
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Abstract
The invention discloses the electrode face finish materials and preparation method and application of a kind of pair of phosphoric acid salt density value, belong to electrochemical material field.In the electrode face finish material to phosphoric acid salt density value, ZrO2- ZnO composite nanometer particle, with bigger serface, hydroxy functional group abundant, material shows good electric conductivity after adulterating multi-walled carbon nanotube.The decorative material improves the sensitivity of the working electrode, also presents good compatibility between membranaceous decorative layer and screen printing electrode, to provide optimized analysis operating environment and condition for phosphatic detection.Test result shows in 0.2mol L‑1H2SO4In the electrolyte solution of/KCl (pH=1.0), phosphate ion minimum detection limit reaches 2 × 10‑8mol L‑1。
Description
Technical field
The present invention relates to field of electrochemical detection, and in particular to the electrode face finish material of a kind of pair of phosphoric acid salt density value and
Preparation method and application.
Background technique
Phosphate is one of most important inorganic salts ingredients in the ecosystem, it can be raw to agricultural production and animals and plants
Long development provides necessary nutrient and nutrient, also can cause a system such as eutrophication pollution to water environment due to content is exceeded
Column adverse effect.Therefore, to researching and developing, one kind can include water body for varying environment, soil progress is quick, sensitive phosphate is dense
It is very crucial for spending detection method.
It is at present colorimetric method, i.e., a certain proportion of ammonium molybdate, Vitamin C about phosphatic testing laboratory's standard method
Acid and antimony (III) are sequentially added in the sample to be tested containing orthophosphates, subsequently form blue phosphomolybdate complex compound.This method
Its minimum detectability is 0.01mg L-1.In addition, chromatography, optical fluorescence method and spectrophotometry can also be used for it is phosphatic
Detection, but these technologies are more demanding for the operation of staff in the detection process, and instrument cost is expensive, is unfavorable for phosphorus
The in situ detection of hydrochlorate ion.
In recent years, with the development of electrochemical measuring technique, more and more substances pass through electrolysis method, potentiometry and conductance
Method obtains the detection of fast quantification in situ.Therefore, carrying out chemical analysis to phosphate ion using electrochemistry voltammetry has one
Fixed market potential.The phosphatic principle of Electrochemical Detection is mainly based upon the complex reaction of phosphate anion and molybdate, energy
It is enough to generate the complex compound with electro-chemical activity, to obtain the concentration of phosphate anion, specific reaction equation (1) indirectly
It is as follows:
[PMo in complex compound12O40]3-With good electro-chemical activity, after being attracted to working electrode surface,
Under the driving of potential change redox reaction can occur for the ion in cyclic voltammetry centered on Mo, thus in scanning figure
Apparent redox peaks peak shape (equation 2) is presented as in, this model electrochemical detection scheme is compared and is commonly used
Phos colorimetric method detection limit it is lower, detection speed faster.
H3PMo(VI)12O40+ reducing agent → [H4PMo(VI)8Mo(V)4O40]3- (2)
In the detection process, the selectivity of electrode is mainly determined by the compatibility degree between sensing interface and phosphate ion
It is fixed.And the most effective method for guaranteeing anion selectivity absorption of energy is chosen and only adsorbs affinity with relatively strong to by measured ion
Chemical structure makes anion be fixed on target with certain special shape then using series reactions such as non-covalent interactions
On electrode.But how to realize that this structure is the technical problem to be solved in the invention.
Summary of the invention
It is an object of the invention to solve problems of the prior art, and provide the electrode of a kind of pair of phosphoric acid salt density value
Face finish material makes its high-affinity to phosphate ion, has good compatibility.
The present invention it is specific the technical solution adopted is as follows:
The preparation method of the electrode face finish material of a kind of pair of phosphoric acid salt density value, its step are as follows:
1) by Zn (Ac)2And ZrOCl2Powder is dissolved in acetum, is slowly added to chitosan after water-bath heat preservation and is mixed
Close liquid；Add alkali to adjust pH of mixed to 11.0~12.0, continues water-bath and generate precipitating；Then to the precipitating of generation successively into
Row washing, dry, high-temperature calcination oxidation obtains ZrO after cooling2ZnO nano composite material；
2) by the ZrO2ZnO nano compound material ultrasound is scattered in ethyl alcohol, forms ZrO2ZnO nano dispersion liquid；So
It is added in backward dispersion liquid and passes through pretreated multi-walled carbon nanotube, heating reaction makes ZrO2- ZnO is compound with multi-walled carbon nanotube
After obtain suspension；After suspension is cooled to room temperature, it is added dropwise to the suspension containing four hydration ammonium heptamolybdates and Nafion
Alcohol mixeding liquid obtains ZrO after evenly mixing2- ZnO/ multi-walled carbon nanotube/tetra- hydration ammonium heptamolybdate nanocomposites are repaired
Liquid is adornd, forms phosphate sensitive membrane for modified electrode surface.
Preferably, in the step 1), Zn (Ac)2And ZrOCl2Powder is dissolved in the acetic acid of 2wt.% with mass ratio 1:1
In solution；The concentration of chitosan is 2.0wt% in the mixed liquor；The alkali is sodium hydroxide solution.
Preferably, bath temperature is kept for 80 DEG C, water-bath time 1h in the step 1).
Preferably, in the step 1), the method for high-temperature calcination oxidation are as follows: the precipitating after drying is placed in Muffle furnace
In, with 25 DEG C of h-1Rate be warming up to 350 DEG C of heated at constant temperature 1 hour, then again with 25 DEG C of h-1Rate be warming up at 450 DEG C
High-temperature oxydation 1 hour.
Preferably, in the step 2), ZrO2ZrO in ZnO nano dispersion liquid2- ZnO concentration is 300mg L-1；Point
The concentration that adds of multi-walled carbon nanotube is 100mg L in dispersion liquid-1。
Preferably, the heating reaction is to be placed in the dispersion liquid after addition multi-walled carbon nanotube in the step 2)
Under 60 DEG C of water baths, heat 24 hours.
Preferably, the concentration that adds of four hydration ammonium heptamolybdates is 0.064mol L in suspension in the step 2)-1,
The concentration that adds of Nafion is 0.1%.
The method that another object of the present invention is to provide a kind of by any of the above-described scheme prepare to phosphoric acid salt density value
Electrode face finish material.
Another object of the present invention is to provide a kind of electrode for phosphate content in test sample, which is three
Electrode system, including working electrode, reference electrode and to electrode are wherein modified on working electrode above-mentioned to phosphoric acid salt density value
Electrode face finish material.
Preferably, three-electrode system is screen printing electrode.
Preferably, the working electrode be carbon electrode, the reference electrode be Ag/AgCl electrode or carbon electrode,
Described is platinum electrode or silver electrode to electrode.
Another object of the present invention is to provide phosphate content detection method in a kind of sample using above-mentioned electrode,
Steps are as follows:
1) the dihydrogen phosphate ions standard solution of several various concentrations is quantitatively added dropwise in working electrode surface, after dry
Three-electrode system is placed in the electrolyte solution of highly acid, electric potential scanning is carried out using cyclic voltammetry, obtains phosphomolybdate
The redox peak to peak current of complex compound；Linear regression is carried out to electric current and phosphate concn, obtains linear pass between the two
It is equation；
2) it will be quantitatively added dropwise three-electrode system containing phosphatic testing sample solution after working electrode surface, drying
It is placed in the electrolyte solution of highly acid, electric potential scanning is carried out using cyclic voltammetry, obtains the oxidation of phosphomolybdate complex compound
Restore peak to peak current；According to the linear relationship equation between electric current and phosphate concn, conversion is obtained in testing sample solution
Phosphate concn.
Preferably, the electrolyte solution is the 0.2mol L of pH=1.0-1H2SO4/ KCl solution.
Preferably, needing in advance to mention the phosphate in pedotheque when the sample to be tested is pedotheque
It takes, specific steps are as follows: after pedotheque is sieved after dry, be quantitatively adding in centrifuge tube, use acetic acid as extractant, carry out
Concussion is extracted；Extracting solution is separated by solid-liquid separation using ultracentrifuge, using the supernatant liquid filtering after centrifugation as sample to be tested
Solution.
Further, the time that the concussion is extracted is preferably 1h；The acetate concentration is preferably 0.50mol L-1。
The beneficial effects of the present invention are the electrode face finish materials and preparation method thereof provided to phosphoric acid salt density value.
The ZrO2In-ZnO/MWCNTs/AMT composite nano materials, ZrO2- Zn composite nanometer particle with bigger serface, enriches
Hydroxy functional group, adulterate multi-walled carbon nanotube after material show good electric conductivity.The decorative material improves the work
The sensitivity of electrode also presents good compatibility between membranaceous decorative layer and screen printing electrode, to be phosphatic
Detection provides optimized analysis operating environment and condition.The working electrode of material modification is directed to phosphorus molybdenum during electric potential scanning
Hydrochlorate complex compound has shown excellent sensitivity, selectivity and stability.It is formed by feature redox peaks it is complete and
The content of the generation and reaction product of its current peak valid certificates phosphate and molybdate complex reaction, thus indirectly
Obtain the corresponding addition concentration of phosphate ion.In 0.2mol L-1H2SO4In the electrolyte solution of/KCl (pH=1.0), phosphoric acid
Salt ion minimum detection limit reaches 2 × 10-8mol L-1。
Detailed description of the invention
Fig. 1 is the scanning electron microscope diagram of different materials in the present invention；Wherein (A)-(C) is respectively ZrO2ZnO nano
Composite material (A), ZrO2- ZnO individually modifies screen printing electrode (B) and ZrO2The composite modified silk screen of-ZnO/MWCNTs/AMT
Print electrode surface (C).
Fig. 2 is ZrO2ZnO nano compound X-ray diffraction spectrum analysis (A) and FTIR spectrum analysis (B).
Fig. 3 is ZrO2- ZnO/MWCNTs/AMT composite modified electrode is in addition 3.7 × 10-7μmol L-1H2PO4-(a) and do not have
There is addition H2PO4-Under the conditions of (b) cyclic voltammetric electrochemical behavior (oxidation peak that -0.067v is molybdenum variation of valence).
Fig. 4 is the selection and electrode anti-interference ability test result of pH；Wherein (A) ZrO2-ZnO/MWCNTs/AMT is multiple
Conjunction modified electrode is in different pH value electrolyte solutions to dihydrogen phosphate ions three kinds of concentration (a:1.47 × 10-7mol L-1,b:3.68×10-7mol L-1,c:1.10×10-6mol L-1) under cyclic voltammetry scan curve；(B)ZrO2-ZnO/
MWCNTs/AMT composite modified electrode is in various concentration Cl-、HCO3 -、SO4 2-Or NO3-(1×10-4mol L-1-3×10-4mol L-1) exist in the case of to 1 × 10-6mol L-1The detection of dihydrogen phosphate ions influences, and interfering ion is not added in Normal expression.
Normal linearity curve of the Fig. 5 between phosphate ion and peak current.
Specific embodiment
Preferred implementation of the invention is described in detail with reference to the accompanying drawing, has enable advantages and features of the invention more
It is easy to be understood by the person skilled in the art, more clear is clearly defined to be made to protection scope of the present invention.
Embodiment 1
In the present embodiment, the electrode face finish material of a kind of pair of phosphoric acid salt density value, i.e. ZrO2-ZnO/ multi wall are provided
Carbon nanotube/tetra- hydration ammonium heptamolybdate (ZrO2- ZnO/MWCNTs/AMT) nanocomposite.Prepare ZrO2-ZnO/MWCNTs/
The process of AMT nanocomposite is as follows:
1) ZrO is prepared2ZnO nano composite material
By the Zn (Ac) of 1.5g2With the ZrOCl of 1.5g2The acetic acid that powder (mass ratio 1:1) is dissolved in 30ml 2wt.% is molten
In liquid, chitosan is then slowly added under 80 DEG C of water baths makes chitosan concentration 2.0wt%, and in the item being stirred continuously
30%NaOH solution is added dropwise under part dropwise, adjusts pH value of solution to 11.0~12.0, continues to be kept for 80 DEG C water-bath 1 hour, in solution
Generate white precipitate.
White precipitate caused by filtering is washed repeatedly with deionized water and ethyl alcohol later, and is placed it in baking oven,
It is dry under the conditions of 100 DEG C.After complete drying to be precipitated, solid precipitating is put into Muffle furnace, with 25 DEG C of h-1Rate heating
To 350 DEG C and heated at constant temperature 1 hour, then proceed to be heated to 450 DEG C of high-temperature oxydations with identical heating rate 1 hour.To solid
Completely after cooling, ZrO is obtained2ZnO nano composite material.
2) ZrO is prepared2-- the nano combined decorative material of ZnO/MWCNTs/AMT
By a certain amount of above-mentioned prepared ZrO2ZnO nano composite material is added in ethyl alcohol, ultrasonic vibration 1h or more, shape
At 300mg L-1ZrO2ZnO nano dispersion liquid.Multi-walled carbon nanotube is pre-processed in advance: by multi wall carbon in dense HNO3
Nanotube (Aladdin, diameter=3-5nm, length=50 μm) flows back 5 hours to activate its molecular activity, then will locate by pre-
The multi-walled carbon nanotube (MWCNTs) of reason is added in dispersion liquid, and concentration of the MWCNTs in dispersion liquid is 100mg L-1, continue to tie up
It holds and is heated 24 hours under 60 DEG C of water baths, obtain suspension.After suspension is cooled to room temperature, in order to increase later period modified membrane
Stability, 0.064mol L is added into the suspension-1Four hydration ammonium heptamolybdate (AMT) and 0.1%Nafion (AMT with
Nafion is previously dissolved in ethyl alcohol and adds again), ZrO is obtained after evenly mixing2- ZnO/ multi-walled carbon nanotube/tetra- seven molybdic acids of hydration
The decorating liquid of ammonium nanocomposite.
3) electrode modification
In the present embodiment, use screen printing electrode that integrated three-electrode system is made: working electrode will be repaired for carbon electrode
Drop-coated is adornd in working electrode surface, ZrO is made after dry2Composite modified screen printing electrode (the ZrO of-ZnO/MWCNTs/AMT2-
ZnO/MWCNTs/AMT/SPE), while using carbon electrode and silver electrode as reference electrode and to electrode.
The performance of the present embodiment is prepared below composite material and electrode is tested.
1, SEM is characterized
For the ease of observing ZnO-ZrO2Composite nanometer particle and its shape characteristic for modifying screen printing electrode surface, are adopted
It, which is observed, with Japanese JSM-5600LV scanning electron microscope forms form and diameter.In the present embodiment, to ZrO2ZnO nano
Structure before and after the form looks and its doping multi-walled carbon nanotube of composite material on modified electrode is characterized, Fig. 1 (A)
For ZrO2ZnO nano composite material scanning electron microscope image, image are shown as Zn (Ac)2And ZrOCl2Contained with the mass ratio of 1:1
When mixing in the acetum of 2.0wt% chitosan, it will form uniform nano bar-shape structure, and the nanometer rods through high-temperature calcination
Length keeps the width of about 100nm within the scope of 300-500nm from tip to bottom.And Fig. 1 (B) is shown, is incited somebody to action when independent
ZrO2ZnO nano composite material is modified in screen printing electrode surface, and structure is passed through compared with material unmodified before
After the processing such as ultrasonic vibration, certain variation is had occurred in nano particle form, and nanometer rods tamped density is more uniform, specific surface area
Have and definitely improve, this kind, which changes, has effectively facilitated increasing for the diffusible site of absorbate.Meanwhile it being received being doped with multi wall carbon
On modified membrane after mitron, scan image Fig. 1 (C) display, every carbon nano tube surface is coated with ZrO2- ZnO is compound to be received
Rice grain, this structure is not only using ZrO2ZnO nano composite material, can also be according to the high-affinity of phosphate ion
Improve the reaction rate and the extent of reaction of phosphomolybdic acid radical ion redox reaction by the high conductivity of multi-walled carbon nanotube.
2, XRD and FTIR characterization
Prepared ZrO is determined using XRD technology2The phase structure of ZnO nano composite material, as shown in Fig. 2 (A), through height
There is significant diffraction maximum in XRD spectra in the calcined composite Nano oxygenate of temperature, (101), (200) in diffraction maximum,
(211) and (100), (002), (101), (102), (110), (103), (112) crystal face correspond respectively to ZrO2Four directions and monocline
The hexagonal wurtzite structure of crystal phase and ZnO.In addition to this this method does not detect the diffraction maximum of other impurities, sufficiently says
The purity of the nanocomposite is illustrated.Based on ZrO2(101) and the main peak peak value of ZnO (101), according to Debye-Scherrer
Equation, the average-size that can calculate two kinds of crystal in the material is respectively 100nm and 130nm, this is also ZrO in material2
It interacts with ZnO obtained.XRD diffraction spectrogram sufficiently demonstrates the ZrO2The high-crystallinity of ZnO nanorod and stable
Molecular conformation feature.
And ZrO2ZnO nano composite oxides are in 0-4000cm-1Interior FTIR spectrum (Fig. 2 (B)) display: according to metal
Oxide is usually lower than 1000cm in absorption band-1When the diffraction maximum vibrated between atom occurs, and this is theoretical, which exists
560cm-1,882cm-1And 918cm-1The wave band of appearance is as caused by the such chemical combination key chattering of Zr-O or Zn-O.And it is based on
ZrO2- ZnO mixing material includes the hydrone of physical absorption, in 651cm-1There is weaker diffraction maximum in place, and 3396cm-1Place
Absorption peak is then attributed to the bending of hydroxyl caused by intermolecular hydrogen bonding and stretching vibration.In 2973cm-1,2872cm-1And 1376cm-1
The diffraction maximum at place derives from the strong stretching vibration of CH functional group, especially-CH3With-CH2The symmetric deformation of group.CH base
Interaction between the presence and hydroxyl group of group plays very big help to effective fixation of nano molecular.
3, XPS is characterized
Using the chemical composition state of zirconium, three kinds of oxygen, zinc elements in nanocomposite prepared by XPS technical research,
XPS characterization result confirms ZrO2The authenticity of ZnO nano compound element composition and structure
4, ZrO2-ZnO/MWCNTs/AMT/SPE electrochemical behavior is analyzed
Using CHI660E electrochemical workstation, circulation volt is carried out for prepared ZrO2-ZnO/MWCNTs/AMT/SPE
Peace method electrochemical analysis detection.10 μ L 3.7 × 10 of film surface drop coating is modified in the ZrO2-ZnO/MWCNTs/AMT of working electrode-7
μmol L-1Dihydrogen phosphate ions H2PO4-Standard solution, it is 1 hour dry, until it is fully applied to electrode surface.Using pre-
First remove the 0.2mol L of oxygen-1H2SO4/ KCl solution (pH=1) is used as electrolyte solution, at room temperature by three electrodes
System is placed in electrolyte solution, choose current potential -1.0V ,+1.0V and -1.0V be respectively the starting point of electric potential scanning, highest point and
Terminal current potential, sweep speed remain 50mVs-1.Meanwhile it being also provided with and not adding 3.7 × 10-7μmol L-1Dihydrogen phosphate from
Sub- H2PO4-The control group of standard solution carries out identical electrochemical analysis detection.
The result shows that 3.7 × 10-7μmol L-1Under conditions of dihydrogen phosphate ions are added and are not added, ZrO2-
Cyclic voltammetric of the ZnO/MWCNTs/AMT/SPE in pH=1 electrolyte solution responds as shown in figure 3, in electric potential scanning process
In, which an anode response peak can occurs on 0.101V always, this is attributed to the hydrionic oxidation of working electrode surface
React (curve a)；And after it joined dihydrogen phosphate ions, curve b occurs one accordingly again at current potential -0.067V
Oxidation peak, the peak reflect the complicated change procedure of molybdenum valence state in phosphomolybdate complex compound, send out in two oxidation peak forming processes
Raw electrochemical reaction is as shown in equation 3 and 4:
It is worth noting that, being that the oxidation peak response current generated at -0.067V will be with phosphate ion concentration in current potential
Increase and improve, therefore the reaction provides a kind of feasible program of electrochemical techniques detection inorganic phosphate salt ion indirectly,
I.e. according to -0.067V place generate oxidation peak response current and phosphate concn between existing linear relationship, conversion obtain to
Phosphate concn in sample solution.In view of the oxidation peak only appearance when electrode surface load has phosphate ion, the electrode
With good detecting and selecting property.
By can be calculated, ZrO2- ZnO/MWCNTs/AMT/SPE and individually having with the screen printing electrode of AMT modification
Imitating surface area is respectively 0.547cm2And 0.172cm2, illustrate ZrO2The utilization of-ZnO/MWCNTs decorative layer not only improves the work
Make the sensitivity of electrode, also present good compatibility between membranaceous decorative layer and screen printing electrode, to be phosphate
Detection provide optimized analysis operating environment and condition.
5, the selection of electrolyte solution pH and the test of electrode anti-interference ability
Phosphatic Electrochemical Detection analysis occurs under conditions of electrode surface potential → just → is born by negative and changed,
Salt compounds centered on molybdenum element are complexed in advance with phosphate, generate the phosphomolybdate complexing with electro-chemical activity
Object, the substance are forced to occur redox reaction to generate response peak-to-peak signal.Mo/H in the reaction+Content ratio is controllable
, test environment must assure that as highly acid.
The present embodiment tests ZrO2The surface-ZnO/MWCNTs/AMT/SPE has 1.47 × 10-7mol L-1、3.68×10- 7mol L-1With 1.10 × 10-6mol L-1In the presence of dihydrogen phosphate ions, pH sweeps cyclic voltammetric within the scope of 1.0-7.0
Retouch the influence (Fig. 4 (A)) of curve oxidation peak peak point current.The result shows that the response of the electrochemical sensor is believed as pH > 1.0
It can continue number under various concentration phosphate ion existence condition to reduce.Therefore, pH=1.0 is by as best under optimal conditions
The pH value of electrolyte solution, the pH of electrolyte solution is no more than 1.0.
In addition, in ZrO2Have 1 × 10 on-ZnO/MWCNTs composite modified electrode-6mol L-1H2PO4-Under existence condition, this
Embodiment has probed into its Cl with 10 times of concentration respectively-、HCO3 -、NO3 -And SO4 2-Testing result generation is done when ion coexists
Disturb influence.In order to probe into the repeatability energy of the working electrode, it is prepared for using modification condition as hereinbefore, method of modifying
Six ZrO2- ZnO/MWCNTs/AMT/SPE, and the H of same amount is added dropwise in electrode surface2PO4 -Ion is placed in pH=1's
0.2mol L-1H2SO4In/KCl electrolyte solution, acquired results calculate relative standard deviation.Four kinds of anion Cl-, HCO3-,
Respectively to phosphate ion in ZrO when SO42- and NO3- is present in electrolyte solution2Sound on-ZnO/MWCNTs/AMT/SPE
Induction signal influences (Fig. 4 (B)).The result shows that with higher concentration (1 × 10-4mol L-1-3×10-4mol L-1) Cl-、
HCO3 -、SO4 2-And NO3 -Respectively under concurrent conditions, 1 × 10-6mol L-1Sound of the phosphate ion in cyclic voltammetric electric potential scanning
Answer curent change amplitude less obvious；Simultaneously, it is contemplated that the concentration of these anion and phosphate ion are dense in actual sample
Degree hardly at a distance of 100 times and its more than.In conclusion such interference signal will not generate too big shadow to final detection result
It rings, which has preferable anti-interference ability.
Embodiment 2
In the present embodiment, using in embodiment 1 with ZrO2- ZnO/MWCNTs/AMT/SPE is three electrode bodies of working electrode
The phosphate content in water sample detects in system.
Detection method are as follows: the dihydrogen phosphate ions standard solution of several various concentrations is quantitatively added dropwise in ZrO2-ZnO/
The surface MWCNTs/AMT/SPE, dry 1 hour until it is overlying on electrode surface completely.In the present embodiment, concentration of standard solution is set
Setting section is 3.7 × 10-8mol L-1-1.10×10-6mol L-1.Then the electrolyte for three-electrode system being placed in highly acid is molten
Liquid (the 0.2mol L of pH=1.0-1H2SO4/ KCl solution) in, current potential is carried out using cyclic voltammetry by electrochemical workstation
Scanning obtains redox peaks (place -0.067V) peak current of phosphomolybdate complex compound.Line is carried out to electric current and phosphate concn
Property return, obtain linear relationship equation between the two.
As a result as shown in figure 5, working as KH2PO4Concentration of standard solution is in 3.7 × 10-8mol L-1-1.10×10-6mol L-1
In range, linear increase, the equation of linear regression between oxidation peak response current and phosphate concn is presented in electrode peak current are as follows:
Ip=86.655 [H2PO4 -]+2.395, coefficient R2=0.9936 (n=3).Signal-to-noise ratio is being taken to be slope intercept standard deviation
Under conditions of 3 times, H2PO4 -Minimum detection limit (LOD) be 2 × 10-8mol L-1.In order to investigate the repeatable of the working electrode
Property, this experiment is prepared for the identical electrochemical working electrode of six modification conditions, 3.7 × 10-7mol L-1There are items for phosphate
Under part, the relative standard deviation (RSD) of gained measurement result is lower than 6% (5.8%), shows the height of the electrochemical sensing system
Reproducibility.
In actual water determination, will can quantitatively be added dropwise containing phosphatic testing sample solution in working electrode table
Face, dry 1 hour until it is overlying on electrode surface completely.Then dry 1 hour until its be overlying on electrode surface completely, equally will
Three-electrode system is placed in electrolyte solution (the 0.2mol L of pH=1.0 of highly acid-1H2SO4/ KCl solution) in, using circulation
Voltammetry carries out electric potential scanning, obtains the redox peak to peak current of phosphomolybdate complex compound.According to electric current and phosphate concn
Between equation of linear regression, can convert to obtain the phosphate concn in testing sample solution.
It is first quantitatively added dropwise when in the present invention, containing phosphatic prepare liquid on the working electrode (s, is placed in electricity again after dry
Electric potential scanning is carried out in electrolyte solution.This is because the phosphate of detection is trace, directly it is mixed in use in electrolyte and follows
When ring voltammetry carries out electric potential scanning, it is not easy to appearance.And electric potential scanning is carried out after being pre-dried in being placed in electrolyte solution,
Can preferably appearance, improve measurement accuracy.
But in other embodiments, if phosphate content is higher, prepare liquid can also quantitatively be mixed in electrolyte solution
It closes, then mixed liquor is directly added drop-wise on three-electrode system or three-electrode system is placed in mixed liquor, carry out electric potential scanning.
Or it is directed to trace phosphate, prepare liquid can also quantitatively be mixed in electrolyte solution, then directly be added drop-wise to mixed liquor
It is placed in mixed liquor on three-electrode system or by three-electrode system, using square wave voltammetry electric potential scanning.
Embodiment 3
Testing sample solution in embodiment 2 is aqueous solution, can be directly used for the phosphate content in detection water sample.But it is false
It such as needs to measure the phosphate content in pedotheque, then needs in advance to mention inorganic phosphate salt ion in pedotheque
It takes.Extracting parameter is optimized below based on identical three-electrode system in embodiment 2, to ensure Phos in pedotheque
The content of hydrochlorate utmostly changes ground reaction on cyclic voltammetry curve.Therefore optimum extraction agent needed for will not only make phosphate
The ion for being completely dissolved, and itself being included will not generate interference to testing result, that is, will not influence the electricity of redox peaks
Position current value.In the present embodiment, four kinds of extractant acetic acid, sodium bicarbonate, potassium sulfate and MES buffer are waited as extractant
Select solution.
It is screened firstly, 1.0g is added in more 50mL centrifuge tubes by drying, and by the sieve of 0.5mm diameter sieve pore
Soil powder afterwards is arranged the test of multiple groups difference extractant, adds 20mL 0.50mol L respectively in different tests group-1HAc、
NaHCO3、K2SO4Extractant is used as with one of MES solution.Then 1mL 0.025mol L is added into each centrifuge tube again-1KHP is molten
Liquid is as ionic strength adjustor.Centrifuge tube is placed in constant-temperature table (170rpm, 25 DEG C) carry out concussion extraction, this reality
It applies example simultaneously to optimize the concussion time, respectively 10 minutes, 20 minutes, 30 minutes, 1 hour and 2 hours.It is complete in mixture
After concussion, it is set to be separated by solid-liquid separation (5000rpm, 20 minutes, 25 DEG C) using ultracentrifuge.By the liquid after centrifugation again mistake
It filters and is transferred in 25mL centrifuge tube, place it in 4 DEG C of environment and store before sample is detected.
Test result shows that the preferred sequence of extractant is HAc > NaHCO3>K2SO4>MES.Acetic acid solvent is used as and most preferably mentions
Agent is taken, the cyclic voltammetry curve line style formed with the phosphate ion of Extraction of acetic acid in the electric potential scanning stage is complete, and has clearly
Redox peaks occur, response signal is also very strong.And for extraction time, earthquake extraction time is 1 hour
Under the conditions of, final detection effect is shown as best.Therefore optimal conditions are extracted in the concussion of soil are as follows: with 0.50mol L-1Acetic acid is
Extractant, the time for shaking extraction are set as 1h.
With optimal conditions, electrochemistry concentration analysis is carried out to the sample of phosphate-containing ion after extraction, uses micro-injection
Device pipettes screen printing electrode surface of the 10 μ L sample solution drop coatings to after being modified and is placed in after being dried at room temperature for 1h
0.2mol L-1H2SO4In/KCl (pH=1) electrolyte solution, electric potential scanning is carried out using cyclic voltammetry, to obtain phosphorus molybdenum
The redox peak to peak current of hydrochlorate complex compound, according to linear relationship existing between electric current and phosphate concn, and then indirectly
Determine the concentration of soluble phosphate ion in sample.Meanwhile in order to assess inorganic phosphate in electrochemistry voltammetric determination soil
The testing result of above-mentioned cyclic voltammetry is compared by the feasibility of salt ion with State Standard Colorimetry acquired results, and assessment should
The accuracy in detection of working electrode.Pedotheque is taken respectively from three ground of Guangdong, Hunan and Jiangsu, two samples in every ground.
The testing result such as table 1 of State Standard Colorimetry and cyclic voltammetry for inorganic phosphate salt ionic concentration in same sample
Shown, wherein cyclic voltammetry is by adjusting pH value, so that inorganic phosphate is mainly with H2PO4-Form participate in electrochemistry it is anti-
It answers, and standard colorimetric rule is tested according to the complex reaction occurred between conventional phosphate and molybdate.Test result is aobvious
Show, phosphate concn obtained by colorimetric method is slightly below cyclic voltammetric technology, and result conjecture may be ascorbic acid in colorimetric method
Caused by being added, which can destroy the electronics transfer during redox reaction, so that the complicated phosphoric acid of 10%-20%
Salt compound is unable to get identification in the detection process.
1 State Standard Colorimetry of table and cyclic voltammetry are compared for soil phosphate ion concentration testing result
Above-mentioned embodiment is only a preferred solution of the present invention, so it is not intended to limiting the invention.Have
The those of ordinary skill for closing technical field can also make various changes without departing from the spirit and scope of the present invention
Change and modification.Therefore all mode technical solutions obtained for taking equivalent substitution or equivalent transformation, all fall within guarantor of the invention
It protects in range.
Claims (10)
1. the preparation method of the electrode face finish material of a kind of pair of phosphoric acid salt density value, which is characterized in that steps are as follows:
1) by Zn (Ac)2And ZrOCl2Powder is dissolved in acetum, is slowly added to chitosan after water-bath heat preservation and is mixed
Liquid；Add alkali to adjust pH of mixed to 11.0~12.0, continues water-bath and generate precipitating；Then the precipitating of generation is successively carried out
Washing, dry, high-temperature calcination oxidation obtains ZrO after cooling2ZnO nano composite material；
2) by the ZrO2ZnO nano compound material ultrasound is scattered in ethyl alcohol, forms ZrO2ZnO nano dispersion liquid；Then to
It is added in dispersion liquid and passes through pretreated multi-walled carbon nanotube, heating reaction makes ZrO2After-ZnO and multi-walled carbon nanotube are compound
To suspension；After suspension is cooled to room temperature, four hydration ammonium heptamolybdates and Nafion are added to the suspension, after evenly mixing
Obtain ZrO2- ZnO/ multi-walled carbon nanotube/tetra- hydration ammonium heptamolybdate nanocomposites decorating liquid, is used for modified electrode surface
Form phosphate sensitive membrane.
2. as described in claim 1 to the preparation method of the electrode face finish material of phosphoric acid salt density value, which is characterized in that institute
It states in step 1), Zn (Ac)2And ZrOCl2Powder is dissolved in the acetum of 2wt.% with mass ratio 1:1；The mixed liquor
The concentration of middle chitosan is 2.0wt%；The alkali is sodium hydroxide solution.
3. as described in claim 1 to the preparation method of the electrode face finish material of phosphoric acid salt density value, which is characterized in that institute
It states in step 1), bath temperature is kept for 80 DEG C, water-bath time 1h.
4. as described in claim 1 to the preparation method of the electrode face finish material of phosphoric acid salt density value, which is characterized in that institute
It states in step 1), the method for high-temperature calcination oxidation are as follows: the precipitating after drying is placed in Muffle furnace, with 25 DEG C of h-1Rate heating
To 350 DEG C heated at constant temperature 1 hour, then again with 25 DEG C of h-1Rate be warming up to high-temperature oxydation 1 hour at 450 DEG C.
5. as described in claim 1 to the preparation method of the electrode face finish material of phosphoric acid salt density value, which is characterized in that institute
It states in step 2), ZrO2ZrO in ZnO nano dispersion liquid2- ZnO concentration is 300mg L-1；Multi-walled carbon nanotube in dispersion liquid
Add concentration be 100mg L-1。
6. as described in claim 1 to the preparation method of the electrode face finish material of phosphoric acid salt density value, which is characterized in that institute
It states in step 2), the heating reaction is heated for the dispersion liquid after addition multi-walled carbon nanotube to be placed under 60 DEG C of water baths
24 hours.
7. as described in claim 1 to the preparation method of the electrode face finish material of phosphoric acid salt density value, which is characterized in that institute
It states in step 2), the concentration that adds of four hydration ammonium heptamolybdates is 0.064mol L in suspension-1, the concentration that adds of Nafion is
0.1%.
8. a kind of electrode face finish material to phosphoric acid salt density value prepared such as any the method for claim 1~7.
9. a kind of electrode for phosphate content in test sample, which is characterized in that the electrode is three-electrode system, including
Working electrode, reference electrode and to electrode, are wherein modified with electrode face finish material as claimed in claim 8 on working electrode
Material.
10. phosphate content detection method in a kind of sample using electrode as claimed in claim 9, which is characterized in that step
It is as follows:
1) the dihydrogen phosphate ions standard solution of several various concentrations is quantitatively added dropwise three after working electrode surface, drying
Electrode system is placed in the electrolyte solution of highly acid, carries out electric potential scanning using cyclic voltammetry, obtains phosphomolybdate complexing
The redox peak to peak current of object；Linear regression is carried out to electric current and phosphate concn, obtains linear relationship side between the two
Journey；The electrolyte solution is preferably the 0.2mol L of pH=1.0-1H2SO4/ KCl solution；
2) it will quantitatively be added dropwise containing phosphatic testing sample solution in working electrode surface, be placed in three-electrode system after dry
In the electrolyte solution of highly acid, electric potential scanning is carried out using cyclic voltammetry, obtains the redox of phosphomolybdate complex compound
Peak to peak current；According to the linear relationship equation between electric current and phosphate concn, conversion obtains the phosphoric acid in testing sample solution
Salinity.
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| CN113189187A (en) * | 2021-03-29 | 2021-07-30 | 浙江大学 | Electrochemical sensor applied to chromium ion detection |
| CN114965659A (en) * | 2022-04-20 | 2022-08-30 | 中国科学院空天信息创新研究院 | Method for detecting phosphate concentration and electrochemical sensor |
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| CN114965659A (en) * | 2022-04-20 | 2022-08-30 | 中国科学院空天信息创新研究院 | Method for detecting phosphate concentration and electrochemical sensor |
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