CN101464426A - Method for measuring hexafluorophosphate ions by amperometry - Google Patents
Method for measuring hexafluorophosphate ions by amperometry Download PDFInfo
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- CN101464426A CN101464426A CNA2008101815216A CN200810181521A CN101464426A CN 101464426 A CN101464426 A CN 101464426A CN A2008101815216 A CNA2008101815216 A CN A2008101815216A CN 200810181521 A CN200810181521 A CN 200810181521A CN 101464426 A CN101464426 A CN 101464426A
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- hexafluorophosphoricacid acid
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Abstract
The invention relates to a method for analyzing and determining hexafluorophosphate ions. A method for measuring hexafluorophosphate ions by an amperometry comprises the following steps: (1) preparing a standard solution of the arsenic tetraphenylanicum chloride: calibrating the concentration of the tetraphenylarsenic chloride solution; (2) preparing a hexafluorophosphate ion solution to be detected: (3) setting the conditions of polarographic analysis: initial potential is-1.25 to-1.78; the sensitivity I is 8; a differential of 2.0; the number of scanning times is 1; step 5; carrying out current titration on hexafluorophosphate ions by using the tetraphenylarsene chloride as a titrant; (4) generated (C)6H5)4AsPF6And then reducing excessive tetraphenylarsenic ions on the mercury drops, and calculating the concentration of the lithium ion battery electrolyte sample to be measured according to the concentration of lithium salt of the diluted sample and the dilution multiple. The invention provides a method for rapidly, accurately and economically measuring hexafluorophosphate ions. The tetraphenylarsonium chloride is stable in solution, can form complex precipitation with hexafluorophosphate, and hexafluorophosphate ions are not easy to be oxidized or reduced when mercury drops, so that the analysis of the hexafluorophosphate ions is based on the reduction characteristic of the tetraphenylarsonium ions.
Description
Technical field:
The present invention relates to a kind of method of assay determination hexafluorophosphoricacid acid ions.
Background technology:
Hexafluorophosphate comprises lithium hexafluoro phosphate, sodium hexafluoro phosphate, Potassium Hexafluorophosphate, ammonium hexafluorophosphate etc., is widely used in the electropolishing of lithium ion battery, catalytic reaction and metal.Lithium hexafluoro phosphate is an important electrolyte in the green high-capacity rechargeable battery electrolytic solution of latest generation, obtained develop rapidly over nearly 10 years, and in the secondary lithium battery of mobile electronic terminal apparatus field such as notebook computer, mobile phone, video camera, weaponry, occupied leading position with its remarkable ratio of performance to price advantage, be considered to 21 century to national economy and the significant new high-tech product of people's lives.
The assay method of hexafluorophosphate has gravimetric method, amperometry, spectrophotometric method, distribution titrimetry.Can make hexafluorophosphate and many ion isolation with nitron or tetraphenylarsonium chloride arsenic precipitation, the mensuration of gravimetric method is exactly the method that designs according to this.Use nitron, owing to itself instability, measurement result is also always unstable for this reason.The use of tetraphenylarsonium chloride arsenic is a great progress.From operation, this method is easier, thereby tetraphenylarsonium chloride arsenic gravimetric method is all adopted in the standard method that hexafluorophosphate is measured.But, because MnO4, high rhenium acid group, perchlorate, bromide, iodide iodate and thiocyanate radical and tetraphenylarsonium chloride arsenic all can generate precipitation, so these ions interference measurement all influences the accuracy of measurement result.The ion of most probable and hexafluorophosphate coexistence also has orthophosphate and Monofluorophosphate in addition, though these ions do not produce precipitation, the gravimetric method running time is long, and result's reappearance is also not so good.
Summary of the invention:
The method that the objective of the invention is to avoid the deficiencies in the prior art part and a kind of measuring hexafluorophosphoricacid acid radical ion by amperometric titration is provided.This method can be used in the study on the synthesis and industrial fast measuring of salt such as lithium hexafluoro phosphate, sodium hexafluoro phosphate, Potassium Hexafluorophosphate, ammonium hexafluorophosphate.Use tetraphenylarsonium chloride arsenic as indicator, according to generating (C
6H
5)
4AsPF
6The principle of the excessive four arsenobenzene ions of reduction on mercury drips is analyzed by amperometric titration subsequently.
Purpose of the present invention can be by realizing by the following technical solutions: a kind of method of measuring hexafluorophosphoricacid acid radical ion by amperometric titration the steps include:
(1) standard solution of preparation tetraphenylarsonium chloride arsenic: accurately measure 8.00ml with saturated NaCl solution towards rare to 100ml, the KI of usefulness 0.02055mol/l standard
3Solution is demarcated, with the potential change of ionic-activity meter mensuration tetraphenylarsonium chloride arsenic solution, the concentration of demarcating the tetraphenylarsonium chloride arsenic solution;
(2) configuration hexafluorophosphoricacid acid ions solution to be measured: take by weighing sample LiPF
60.14～0.16g is 9～11 NH with the pH value
3H
2O-NH
4Cl buffer solution 14～16mL dissolving is diluted to 100mL with redistilled water, concentration 0.009～0.011mol/L; Get the above-mentioned solution of 5-6mL, be added in the former buffer solution, use the KCl solution of 1mol/L then, described KCl solution contains 0.1%TritonX-100, its concentration is 0.0001mol/L when terminal point, is diluted to 54～56mL, adds the animal glue 0.43～0.45mL of concentration 0.004%;
(3) condition of setting polarographic analysis: take-off potential-1.25～-1.78; Sensitivity I is 8; Differential 2.0; Scanning times 1; Step-length 5; As titrant hexafluorophosphoricacid acid ions is carried out amperometric titration with tetraphenylarsonium chloride arsenic, the reaction equation of the amperometric titration of hexafluorophosphoricacid acid ions:
(C
6H
5)
4As
++PF
- 6＝(C
6H
5)
4AsPF
6
(4) (the C of Sheng Chenging
6H
5)
4AsPF
6, excessive four arsenobenzene ions of reduction on mercury drips subsequently, the concentration that calculates lithium-ion battery electrolytes sample to be measured according to the lithium salt and the extension rate of dilute sample.
The method of described measuring hexafluorophosphoricacid acid radical ion by amperometric titration, described hexafluorophosphoric acid includes lithium hexafluoro phosphate, sodium hexafluoro phosphate, Potassium Hexafluorophosphate, ammonium hexafluorophosphate.
Through test, excessive ten times fluoride, hydroxyl, sulfate radical, chloride, phosphate radical and difluorophosphoric acid root all do not produce interference to the result.
The invention has the beneficial effects as follows, the invention provides a kind of method of quick, accurate, economic mensuration hexafluorophosphoricacid acid ions.Tetraphenylarsonium chloride arsenic is stable in solution, can form complex compound sediment with hexafluorophosphate, drips at mercury, and hexafluorophosphoricacid acid ions is difficult for oxidized or reduction, thereby the analysis of hexafluorophosphoricacid acid ions is by the reduction characteristic of four arsenobenzene ions.
Show that from the measurement result of following embodiment this method is at 0.0014～0.01M PF
6 -Use in the scope, for the LiPF of 0.031g
6 -Carry out repeatedly replication, relative standard deviation is ± 0.1%.Sample P F
6 -Measured value in the error allowed band, can satisfy the assay determination requirement.Illustrate hexafluorophosphoricacid acid ions is carried out amperometric titration with tetraphenylarsonium chloride arsenic as titrant method quick and precisely, analysis cost is lower, is applicable to experimental determination.
Embodiment:
Below in conjunction with shown in most preferred embodiment be described in further detail:
1 one kinds of amperometric titrations of embodiment are measured the method for the hexafluorophosphoricacid acid ions of lithium hexafluoro phosphate, the steps include:
(1) standard solution of preparation tetraphenylarsonium chloride arsenic: accurately measure 8.00ml with saturated NaCl solution towards rare to 100ml, the KI of usefulness 0.02055mol/l standard
3Solution is demarcated, and measures the potential change of tetraphenylarsonium chloride arsenic solution with PXS-215 type ionic-activity meter.The drop reaction equation is:
(C
6H
5)
4As
++I
2+I→(C
6H
5)
4AsI
3
Calculate the terminal point of titration with secondary difference quotient method, the concentration of the tetraphenylarsonium chloride arsenic solution that the volume of the standard potassium triiodide solution that is consumed and quilt are demarcated.
Demarcate the concentration of tetraphenylarsonium chloride arsenic solution.
Tetraphenylarsonium chloride arsenic solution concentration titration data is shown in Table 1.Tetraphenylarsonium chloride arsenic solution current potential-standard K I
3Volume is seen shown in Figure 1.
Calculate the terminal point of titration with secondary difference quotient method, the volume of the standard potassium triiodide solution that is consumed is 6.9304mL, is demarcated tetraphenylarsonium chloride arsenic solution concentration to be:
6.9304×0.02055/8.00＝0.017802mol/l
The adding of table 1 titrant and the variation of solution potential
(2) configuration hexafluorophosphoricacid acid ions solution to be measured: take by weighing sample LiPF
60.15g, with the NH of pH value=10
3.H
2O-NH
4Cl buffer solution 15mL dissolving is diluted to 100mL with redistilled water, and concentration is about 0.01mol/L.Get the above-mentioned solution of 5.00mL, be added in the former buffer solution of 15mL, use the KCl solution of 1mol/L then, described KCl solution contains 0.1%TritonX-100, its concentration is 0.0001mol/L when terminal point, is diluted to 55-55mL, adds the animal glue 0.44mL of concentration 0.004%.
(3) connect experimental provision, set the condition of polarographic analysis: take-off potential-1.25～-1.78; Sensitivity I is 8; Differential 2.0; Scanning times 1; Step-length 5; As titrant hexafluorophosphoricacid acid ions is carried out amperometric titration with tetraphenylarsonium chloride arsenic, the reaction equation of the amperometric titration of hexafluorophosphoricacid acid ions:
(C
6H
5)
4As
++PF
- 6＝(C
6H
5)
4AsPF
6
(4) (the C of Sheng Chenging
6H
5)
4AsPF
6, excessive four arsenobenzene ions of reduction on mercury drips subsequently, the concentration that calculates lithium-ion battery electrolytes sample to be measured according to the lithium salt and the extension rate of dilute sample.
As titrant hexafluorophosphoricacid acid ions is carried out amperometric titration with tetraphenylarsonium chloride arsenic described in the step (3), decomposition voltage with respect to saturated mercurous chloride electrode is-1.5V, carries out titration and measurement, occurs until electric current ~ voltage curve.Before near terminal point, titrant at every turn with 0.05 or the volume of 0.1mL add, behind terminal point, each addition of titrant is controlled at 0.1mL, this is to disperse electric current for fear of unnecessary height.Add gelatin and be in order to reduce the formation of gelatinous precipitate suspension,, can measure current value exactly when this sedimentary amount is reduced to 10-4g/L when following.
Polarographic analysis is a kind of microanalysis method fast, is converted into strength of current by tested ion concentration and measures.The only concentration range of DC polarography is 10
-2～10
-4Mol/L, the scope that polarographic titration is measured is 0.1 to 10
-4Mol/L can be low to moderate 10 under appropriate condition
-6The concentration that mol/L is above.To 10
-3The concentration of mol/L, error at measurment are ± 0.1%, 10
-5Mol/L is ± 1%.Therefore, as (C
6H
5)
4As
+With PF
- 6The post precipitation that reacts completely, excessive slightly (C
6H
5)
4As
+Be reduced on the dropping-mercury electrode surface, electric current-voltage spectrogram occurs.
In order to guarantee the accuracy of polarographic analysis, it is pure that the purity of the mercury that uses will reach analysis at least; The distilled water that reagent preparation is used must could use through purifying.In electrolytic cell, add the end liquid (comprising: supporting electrolyte, complexing agent, TritronX-100 and gel etc. are made maximum suppressor) of total amount 10% during experiment, add tested test solution such as PF again
- 6With the dropping-mercury electrode is that negative pole, saturated calomel electrode are that positive pole, platinum electrode are contrast electrode, connects circuit, rises mercury-storage bottle, and making mercury drip drop time is 3～6 seconds, writes down polarogram then.For avoiding producing the oxygen ripple, when adding titrant at every turn, be added in a large amount of mensuration liquid with the reagent of small size after, concentration of oxygen is very little, can not produce electric current in the time that sets, and disturbs not quite, stops to stir static back and measures.
Add supporting electrolyte in the end liquid, and during big 50 to 100 times of the tested ion concentration of concentration ratio, dropping-mercury electrode is to being reduced greatly by the electrostatic interaction of measured ion, thereby eliminated transference cell.In addition, because the reaction of organic substance on dropping-mercury electrode is slower than inorganic ions, and also complicated.The reaction of tetraphenylarsonium chloride arsenic on dropping-mercury electrode generally includes H
+, the pH of electrode surface solution is changed, the disorder of polarogram waveform, so end liquid need add 100mLNH
3H
2O-NH
4Cl buffer solution.
The instrument that the present invention uses comprises:
(1) JP4000 type oscillographic polarograph;
(2) buret is that a minimum scale is that 0.05mL, capacity are 10 ± 0.002mL microburette;
(3) the amperometric titration groove covers rim of a cup with 50 milliliters of poly-tetrafluoro beakers with plastic sheeting, opens an osculum and inserts dropping-mercury electrode (indicator electrode), saturated calomel electrode (contrast electrode), platinum electrode (to electrode) respectively;
(4) FA2004 electronic analytical balance.
(5) PXS-215 type ionic-activity meter.
All volumetric apparatus all pass through calibration.
The reagent that the present invention uses comprises:
(1) (U.S. produces tetraphenylarsonium chloride arsenic, 99.9%) standard solution: with accuracy is that the electronic analytical balance of 0.0001g accurately takes by weighing tetraphenylarsonium chloride arsenic, dissolve in the water, be made into the solution that concentration is about 0.02molL, demarcate with concentration 0.02055mol/L potassium triiodide standard solution then.Above-mentioned solution is used for carrying out the research of amperometric titration and polarogram.
(2) NH of pH value=10
3H
2O-NH
4Cl buffer solution;
(3) the KCl solution of 1mol/L (wherein contain 0.1%TritonX-100, its concentration is 0.0001mol/L when terminal point);
(4) 0.004% animal glue;
(5) lithium hexafluoro phosphate solution: with a certain amount of self-designed L iPF
6, earlier with the dissolving of pH=10 buffer solution, with the redistilled water dilution, TritronX-100 and gel are used as maximum suppressor then;
(6) KI
3Standard solution (0.02055mol/l);
(7) NaCl saturated solution.
Used reagent all is analytically pure.
Choose a kind of up-to-date commerical grade lithium hexafluoro phosphate sample of purchasing (content 99.8%), adopt electric current polarography and gravimetric method to compare mensuration respectively, as titrant hexafluorophosphoricacid acid ions is carried out amperometric titration with tetraphenylarsonium chloride arsenic, the result who measures is as shown in table 2, as precipitation agent hexafluorophosphoricacid acid ions is carried out the mensuration of gravimetric method with tetraphenylarsonium chloride arsenic, the result of mensuration is as shown in table 3.
The result shows, with the sample P F of two kinds of methods mensuration
- 6Content mean value is consistent, illustrates that be quick, accurate, economic analytical approach with tetraphenylarsonium chloride arsenic as the method that titrant carries out amperometric titration to hexafluorophosphoricacid acid ions.
Table 2 carries out amperometric titration as titrant to hexafluorophosphoricacid acid ions with tetraphenylarsonium chloride arsenic
Table 3 carries out the mensuration of gravimetric method to hexafluorophosphoricacid acid ions as precipitation agent with tetraphenylarsonium chloride arsenic
Embodiment 3
Prepare in the research of lithium hexafluoro phosphate at solvent method, carry out 6 replicate determinations, the standard deviation of calculation sample and relative standard deviation (R for same a kind of sample of making synthetic lithium hexafluoro phosphate product by oneself
SDValue), test shows that the precision of method can satisfy the requirement of assay determination.Measurement result is shown in Table 4.
Table 4 Precision test result
4 one kinds of amperometric titrations of embodiment are measured the method for the hexafluorophosphoricacid acid ions of sodium hexafluoro phosphate, and its step is identical with embodiment 1.
5 one kinds of amperometric titrations of embodiment are measured the method for the hexafluorophosphoricacid acid ions of Potassium Hexafluorophosphate, and its step is identical with embodiment 1.
6 one kinds of amperometric titrations of embodiment are measured the method for the hexafluorophosphoricacid acid ions of ammonium hexafluorophosphate, and its step is identical with embodiment 1.
Claims (2)
1. the method for a measuring hexafluorophosphoricacid acid radical ion by amperometric titration the steps include:
(1) standard solution of preparation tetraphenylarsonium chloride arsenic: accurately measure 8.00ml with saturated NaCl solution towards rare to 100ml, the KI of usefulness 0.02055mol/l standard
3Solution is demarcated, with the potential change of ionic-activity meter mensuration tetraphenylarsonium chloride arsenic solution, the concentration of demarcating the tetraphenylarsonium chloride arsenic solution;
(2) configuration hexafluorophosphoricacid acid ions solution to be measured: take by weighing sample LiPF
60.14～0.16g is 9～11 NH with the pH value
3H
2O-NH
4Cl buffer solution 14～16mL dissolving is diluted to 100mL with redistilled water, concentration 0.009～0.011mol/L; Get the above-mentioned solution of 5～6mL, be added in the former buffer solution, use the KCl solution of 1mol/L then, described KCl solution contains 0.1%TritonX-100, its concentration is 0.0001mol/L when terminal point, is diluted to 54～56mL, adds the animal glue 0.43～0.45mL of concentration 0.004%;
(3) condition of setting polarographic analysis: take-off potential-1.25～-1.78; Sensitivity I is 8; Differential 2.0; Scanning times 1; Step-length 5; As titrant hexafluorophosphoricacid acid ions is carried out amperometric titration with tetraphenylarsonium chloride arsenic, the reaction equation of the amperometric titration of hexafluorophosphoricacid acid ions:
(C
6H
5)
4As
++PF
- 6＝(C
6H
5)
4AsPF
6
(4) (the C of Sheng Chenging
6H
5)
4AsPF
6, excessive four arsenobenzene ions of reduction on mercury drips subsequently, the concentration that calculates lithium-ion battery electrolytes sample to be measured according to the lithium salt and the extension rate of dilute sample.
2. the method for measuring hexafluorophosphoricacid acid radical ion by amperometric titration as claimed in claim 1 is characterized in that described hexafluorophosphoric acid includes lithium hexafluoro phosphate, sodium hexafluoro phosphate, Potassium Hexafluorophosphate, ammonium hexafluorophosphate.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106353383A (en) * | 2016-10-10 | 2017-01-25 | 常州大学 | Sensor for detecting hexafluorophosphate ions |
-
2008
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106353383A (en) * | 2016-10-10 | 2017-01-25 | 常州大学 | Sensor for detecting hexafluorophosphate ions |
| CN106353383B (en) * | 2016-10-10 | 2019-05-28 | 常州大学 | A kind of sensor detecting hexafluorophosphoricacid acid ions |
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Application publication date: 20090624 |