CN114441608B - Detection method and detection device for valence state distribution of metal ions - Google Patents
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Abstract
The application discloses a detection method and a detection device for valence state distribution of metal ions; the detection method comprises the following steps: a) Measuring a valence state distribution-potential standard curve of the ion standard solution to be measured; b) Measuring a pH-potential standard curve of the standard solution; c) Measuring the potential of the standard solution of the ions to be measured, and determining the correction coefficients of temperature and pressure to the potential; d) Measuring the potential, the pH, the temperature and the pressure of the actual solution, and calculating the valence distribution of the ions to be detected in the solution according to the valence distribution-potential standard curve and the pH-potential standard curve given in the steps a) and b) and by combining the correction of the temperature and the pressure given in the step c) on the potential. The detection device structurally comprises: the device comprises a detection cell, a reference electrode, a working electrode, a temperature sensor, a pressure sensor and a pH sensor. The detection method and the detection device of the invention are adopted to measure the valence state distribution of the metal ions to be detected, and the absolute error is not more than plus or minus 0.01.
Description
Technical Field
The application relates to a detection method and a detection device for valence state distribution of metal ions, belonging to the technical field of electrochemistry and analytical chemistry.
Background
H 2 S is a colorless, highly toxic and corrosive gas generally derived from various chemical processes. Treatment of H by electrolysis 2 S gas, the reaction condition is mild, and hydrogen can be generated at the same time, compared with the traditional Claus technology, H is avoided 2 S waste of chemical energy. For H 2 S indirect electrolytic treatment process in the presence of electricityThe positive and negative electrodes of the electrolysis unit respectively adopt different metal ion pairs as carriers for transporting electrons, which respectively participate in H absorption through oxidation reaction 2 S and hydrogen evolution through reduction reaction, finally realizing integral H 2 And (4) S decomposition reaction. Since the whole treatment process system involves valence transformation of various metal ions and circulation of solution, a detection means is needed to realize measurement of ion valence distribution at specific positions in the system, so that the whole system can be dynamically adjusted during operation.
Disclosure of Invention
The invention aims to provide a method for detecting valence state distribution of metal ions.
Another object of the present invention is to provide a detection apparatus capable of implementing the above detection method.
In one aspect of the present application, a method for detecting a valence distribution of a metal ion is provided, the method comprising the steps of:
a) Preparing a group of metal ion standard solutions I to be detected with the same total concentration, the same pH value and different valence state distributions, and performing concentration measurement at a temperature T 1 And pressure P 1 Measuring a valence state distribution-potential standard curve of the standard solution I under the condition;
b) Preparing a group of metal ion standard solutions II to be detected with the same total concentration, the same valence state distribution and different pH values, and performing concentration measurement at a temperature T 2 And pressure P 2 Measuring the pH-potential standard curve of the standard solution II under the condition;
c) Selecting a metal ion standard solution III to be detected with specific total concentration, valence state distribution and pH value, and carrying out heat treatment at different temperatures T 3 And pressure P 3 Measuring the potential of the standard solution III under the condition, and measuring the correction coefficients of temperature and pressure to the potential;
d) Measuring the potential, pH, temperature and pressure of the actual solution to be measured, and calculating the valence distribution of ions to be measured in the solution according to the valence distribution-potential standard curve given in the step a) and the pH-potential standard curve given in the step b) in combination with the correction coefficient of the temperature and pressure to the potential given in the step c).
For the electrochemical half-reaction involving the metal ions in solution: m l m+ →M h (m+n)+ +ne - Wherein M is l m+ Is low-valent ion of metal ion pair, and has valence of + M, M h (m+n)+ The valence of the high valence ion in the metal ion pair is plus (m + n), and n is the electron transfer number corresponding to the half reaction. According to the Nernst equation, the potential of the solution and the valence state distribution of the metal ions satisfy the following relationship:
wherein:
is the actual potential of the metal ion to be measured in the solution,
r is an ideal gas constant (8.314 J.mol.) for the standard potential of the metal ion to be measured -1 ·K -1 ) T is temperature, F is Faraday constant (96485℃ Mol) -1 )，[M h ]Is the concentration of the high valence ion in the metal ion pair, [ M l ]Is the concentration of medium and low valence ions in the metal ion pair, n is the electron transfer number, X h Is the proportion of ions of high valence, having X h ＝[M h ]/([M h ]+[M l ]). Taking into account the actual measured potential
Wherein
As the potential of the reference electrode, there are:
thus, step a) of the detection method is aimed at measuring X h And
determining the potential of the reference electrode under specific temperature and pressure conditions
For having H + Participating half reaction: m l m+ +xH 2 O→M h O x (2x-m-n)- +2xH + +ne - Wherein M is l m+ Is a low valence ion of the metal ion pair, and has a valence of + M, M h O x (2x-m-n)- Is the high valence ion in the metal ion pair, the valence state is- (2 x-m-n), n is the electron transfer number corresponding to the half reaction, 2x is the H participated in the half reaction + The number of the cells. According to the nernst equation, the potential of the solution satisfies the following relationship with the valence distribution and pH of the metal ion:
wherein [ M ] is h O x (2x-m-n)- ]Is the concentration of the high valence ion in the metal ion pair, [ M l ]Is the concentration of low valence ions in the metal ion pair, n is the electron transfer number, and 2x is the H participating in the half-reaction + E is the base of the natural logarithm, X h Is the proportion of ions of high valence, having X h ＝[M h O x (2x-m-n)- ]/([M h O x (2x-m-n)- ]+[M l ]). It was found that the actual potential of the solution measured at this time should be linear with pH. On the other hand, for no H + The half-reaction involved, due to pH, will also be at the actual potential of the solution
The micro influence is generated, the linear relation can be approximated in a certain pH range, and the following conditions are met:
where δ is the correction factor of pH versus potential (for H) + The actual value of δ should be close to 2 x/lge) for the half reaction to take place. Thus, the object of step b) of the detection method is to determine the pH by measuring
The relationship determines the correction factor δ of pH versus potential.
From equation (4), it can also be found that the temperature T of the solution is related to the measured potential
There are also effects. In addition, the temperature T also affects the potential of the reference electrode
The influence relationship when the temperature range is not large can be expressed as:
wherein
As reference electrode at T 0 Potential at temperature,. Epsilon T The temperature coefficient of the reference electrode. Similarly, consider the pressure P versus the reference electrode potential
The influence relationship when the pressure range is not large can be expressed as:
wherein
As a reference electrode at P 0 Potential under pressure,. Epsilon P The pressure coefficient of the reference electrode. The purpose of step c) of the detection method is therefore to measure the potential of the reference electrode at different temperatures and pressures
Determination of the temperature coefficient ε of a reference electrode T And coefficient of pressure ε P 。
When actually measuring the solution to be measured, first of all at a temperature T 0 And pressure P 0 Measuring the potential of a reference electrode under conditions
Then according to the temperature coefficient epsilon of the reference electrode T And coefficient of pressure ε P And the potential of the reference electrode under the conditions of the current temperature T and the current pressure P can be calculated
Then, according to the standard electrode potential of the ions to be measured
Actual reference electrode potential
The actually measured potential can be obtained according to the relation given by the formula (4) by the temperature T, the number n of semi-reaction transfer electrons, the pH of the solution and the correction coefficient delta of the pH to the potential
Conversion to the ratio X of the high valence ion h ：
I.e. the valence state distribution of the metal ions to be measured.
Optionally, the metal ion to be detected is an ion pair composed of two different valence ions of the same metal;
optionally, the metal ion to be detected is selected from V 3+ /V 2+ 、VO 2+ /V 3+ 、VO 2 + /VO 2+ 、CrO 4 2- /Cr 3+ 、Cr 2 O 7 2- /Cr 3+ 、MnO 4 - /Mn 2+ Or Fe 3+ /Fe 2+ One of (1);
wherein, the ion pair V 3+ /V 2+ And Fe 3+ /Fe 2+ Corresponds to no H + The half reaction is participated, and the actual potential of the half reaction is less influenced by the pH value of the solution; and ion pair VO 2+ /V 3+ 、VO 2 + /VO 2+ 、CrO 4 2- /Cr 3+ 、Cr 2 O 7 2- /Cr 3+ And MnO 4 - /Mn 2+ Corresponding to H + The actual potential of the half-reaction is greatly influenced by the pH value of the solution.
Alternatively, the valence distribution is the proportion of higher valence metal ions in the ion pair in the total metal ion pair.
For convenience, the valence distribution is the ratio X of the higher valence metal ion in the ion pair to the total metal ion pair h Having X h ＝[M h ]/([M h ]+[M l ])。
Optionally, the total concentration of the metal ions to be detected in the standard solution I in the step a) is selected from 0.01mol/L, 0.02mol/L, 0.05mol/L, 0.1mol/L, 0.2mol/L, 0.5mol/L, 1.0mol/L, 5.0mol/L or 10.0mol/L;
the total concentration of the metal ions to be detected in the standard solution II in the step b) is selected from 0.01mol/L, 0.02mol/L, 0.05mol/L, 0.1mol/L, 0.2mol/L, 0.5mol/L, 1.0mol/L, 5.0mol/L or 10.0mol/L;
the total concentration of the metal ions to be detected in the standard solution III in the step c) is selected from 0.01mol/L, 0.02mol/L, 0.05mol/L, 0.1mol/L, 0.2mol/L, 0.5mol/L, 1.0mol/L, 5.0mol/L or 10.0mol/L;
the total concentration of the metal ions to be detected in the actual solution to be detected in the step d) is 0.01-10 mol/L.
For convenience, the total concentration of the metal ions to be measured in the standard solutions in steps a), b) and c) may be the same.
In order to reduce the error as much as possible, the total concentration of the metal ions to be detected in the standard solution in the steps a), b) and c) should be close to the total concentration of the metal ions to be detected in the actual solution to be detected in the step d).
Alternatively, in the standard solution I in step a), the valence distributions are 0.05, 0.1, 0.25, 0.5, 0.75, 0.9 and 0.95;
in the standard solution II in the step b), the valence state distribution is selected from 0.05, 0.1, 0.25, 0.5, 0.75, 0.9 or 0.95;
preferably, in the standard solution II in the step b), the valence state distribution is 0.5;
in the standard solution III in step c), the valence state distribution is selected from 0.05, 0.1, 0.25, 0.5, 0.75, 0.9 or 0.95.
Preferably, in the standard solution III in step c), the valence state distribution is 0.5.
When the ratio of the high valence state ions of the metal to be detected in the standard solution in the steps b) and c) is 0.5, ln [ X ] exists h /(1-X h )]=0, which facilitates data processing and the calculation of other relevant parameters.
Alternatively, in the standard solution I in step a), the pH is selected from-1, 0, 1, 2, 3, 4, 5, 6 or 7;
in the standard solution II in the step b), the pH is selected from at least three of-1, 0, 1, 2, 3, 4, 5, 6 or 7;
in the standard solution III in the step c), the pH is selected from-1, 0, 1, 2, 3, 4, 5, 6 or 7;
in the actual solution to be measured in the step d), the pH value is-1-7.
For convenience, the pH of the standard solutions in steps a) and c) may be the same.
In order to minimize errors, the pH of the standard solutions in steps a) and c) should be close to the pH of the actual solution to be tested in step d), and the pH of the at least three different pH standard solutions in step b) should also be close to the pH of the actual solution to be tested in step d).
Optionally, in step a), said T 1 Selected from 0 deg.C, 10 deg.C, 20 deg.C, 30 deg.C, 40 deg.C, 50 deg.C, 60 deg.C, 70 deg.C or 80 deg.C;
said P in step a) 1 Selected from 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa or 1.0MPa;
said T in step b) 2 Selected from 0 deg.C, 10 deg.C, 20 deg.C, 30 deg.C, 40 deg.C, 50 deg.C, 60 deg.C, 70 deg.C or 80 deg.C;
said P in step b) 2 Selected from 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa or 1.0MPa;
t described in step c) 3 At least three selected from 0 deg.C, 10 deg.C, 20 deg.C, 30 deg.C, 40 deg.C, 50 deg.C, 60 deg.C, 70 deg.C or 80 deg.C;
p as described in step c) 3 At least three selected from 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa or 1.0MPa;
the temperature of the actual solution to be measured in the step d) is 0-80 ℃;
the pressure of the actual solution to be measured in the step d) is 0.1-1.0 MPa.
For convenience, the specific temperatures and pressures described in steps a) and b) may be the same.
In order to minimize the error, the specific temperature and pressure conditions described in steps a) and b) should be close to the temperature and pressure of the actual test solution in step d), and the at least three different temperature and pressure conditions described in step c) should also be close to the temperature and pressure of the actual test solution in step d).
In another aspect of the present application, a detection apparatus for detecting a valence distribution of a metal ion is provided, and the detection apparatus is used in the detection method for a valence distribution of a metal ion.
The detection method can be realized in the device for detecting the valence state distribution of the metal ions.
Optionally, the detection device includes: a detection cell, an electrochemical workstation; and a reference electrode, a working electrode, a temperature sensor, a pH sensor and a pressure sensor which are positioned in the detection cell;
the electrochemical work is electrically connected with the reference electrode and the working electrode and is used for obtaining the potentials of the standard solution I, the standard solution II, the standard solution III and the solution to be detected;
the temperature sensor is used for obtaining the temperatures of the standard solution I, the standard solution II, the standard solution III and the solution to be detected;
the pH sensor is used for obtaining the pH values of the standard solution I, the standard solution II, the standard solution III and the solution to be detected;
the pressure sensor is used for obtaining the pressure of the standard solution I, the standard solution II, the standard solution III and the solution to be detected.
Optionally, the reference electrode is selected from Hg/Hg 2 SO 4 Electrode, hg/Hg 2 Cl 2 One of an electrode or an Ag/AgCl electrode;
optionally, the working electrode is selected from one of a glassy carbon electrode, a graphite electrode, a gold electrode, a platinum electrode or a silver electrode;
the detection method requires that the standard solution and the solution to be detected are acidic, so that a detection pool in the detection device is required to be made of acid-resistant materials, the reference electrode and the working electrode are electrodes suitable for the acidic condition, and the temperature sensor, the pH sensor and the pressure sensor are also resistant to acid corrosion.
Optionally, a liquid inlet is formed in the lower part of the side wall of the detection pool; the upper portion of the pool lateral wall of the detection pool is provided with a liquid outlet which can be used for on-line detection.
When measuring the standard solution or the static solution to be measured, closing the liquid inlet and the liquid outlet; when the dynamic solution to be detected is measured on line, the detection pools can be connected in series or in parallel into an external solution system through the liquid inlet and the liquid outlet.
Optionally, the detection method and the detection apparatus are used to measure the valence state distribution of the metal ions to be detected, and the absolute error of the valence state distribution is not greater than ± 0.01.
Because the detection method simultaneously considers the influence factors of the ion concentration and distribution in the solution and the temperature and pressure of the environment, the accuracy is better.
Compared with the prior art, the detection method and the detection device for the valence state distribution of the metal ions have the following advantages:
1) The detection method simultaneously considers the influence factors of the ion concentration and distribution in the solution and the temperature and pressure of the environment, so the accuracy is better, and the absolute error can be realized to be not more than +/-0.01;
2) The detection device has a simple structure and is convenient to assemble, disassemble and maintain;
3) The detection device uses a detection pool made of acid-resistant materials, a temperature sensor, a pH sensor and a pressure sensor, and the reference electrode and the working electrode are electrodes suitable for the acidic condition, so that the detection device works stably under the acidic condition and has good repeatability of a measurement result;
4) The detection method and the detection device have high response speed, and can realize real-time online monitoring of the valence state distribution of the metal ions.
Drawings
Fig. 1 is a schematic structural diagram of the metal ion valence distribution detection apparatus.
FIG. 2 shows the actual potentials φ' and Fe of the Fe standard solution in example 1 3+ Ratio of X h A graph of the relationship (c). For facilitating linear fitting, taking phi' -phi on the ordinate 0 Taking ln [ X ] as abscissa h /(1-X h )]。
FIG. 3 is a graph of the actual potential φ' versus pH for the Fe standard solutions of example 2.
FIG. 4 shows Hg/Hg in example 3 2 SO 4 Reference electrode potential phi Ref Graph with temperature T.
FIG. 5 shows Hg/Hg in example 4 2 SO 4 Reference electrode potential phi Ref Graph against pressure P.
FIG. 6 is a diagram illustrating the online detection result of the Fe ion valence distribution of the solution to be detected in example 5. Wherein the dotted line is Fe calculated according to the charge amount of the charge/discharge meter 3+ The solid line represents Fe calculated by the detection method of the present invention 3+ The percentage, square mark, is Fe measured by potentiometric titrator 3+ Ratio of occupation.
Wherein:
1. a detection cell; 2. a reference electrode; 3. a working electrode; 4. a temperature sensor; 5. a pH sensor; 6. a pressure sensor; 7. a liquid inlet; 8. liquid outlet
Detailed Description
The present application will be described in detail with reference to examples, but the present application is not limited to these examples.
The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified.
Example 1
The detection device described in this embodiment is shown in fig. 1, and the structure thereof includes: a detection cell 1, and a reference electrode 2, a working electrode 3, a temperature sensor 4, a pH sensor 5, and a pressure sensor 6 disposed in the detection cell 1. The lower part and the upper part of the side wall of the detection pool 1 are respectively provided with a liquid inlet 7 and a liquid outlet 8. When a standard solution or a static solution to be detected is measured, the liquid inlet 7 and the liquid outlet 8 are closed; when the dynamic solution to be detected is measured on line, the detection cells can be connected in series or in parallel into an external solution system through the liquid inlet 7 and the liquid outlet 8.
Example 2
This example illustrates for Fe 3+ /Fe 2+ Standard solutions, measuring Hg/Hg under specific temperature and pressure conditions according to step a) of the detection method of the invention 2 SO 4 The potential of the reference electrode.
Using FeSO 4 、Fe 2 (SO 4 ) 3 And H 2 SO 4 Preparing a series of standard solutions with total Fe ion concentration of 0.5mol/L and pH of 0, wherein Fe is contained in the standard solutions 3+ Are 0.05, 0.1, 0.25, 0.5, 0.75, 0.9 and 0.95, respectively. The reference electrode is selected to be Hg/Hg 2 SO 4 Electrode and working electrodeThe detection device as described in example 1 was assembled with a glassy carbon electrode, a standard solution was added to the detection cell, and the reference and working electrodes were connected to an electrochemical workstation. The actual potentials of the series of standard solutions were measured at 20 ℃ and 0.1MPa, respectively, and then fitted according to the formula (2).
As a result, hg/Hg is obtained 2 SO 4 The electrode potential of the reference electrode was 0.773VvsRHE (FIG. 2) at 20 ℃ and 0.1 MPa.
Example 3
This example illustrates for Fe 3+ /Fe 2+ The standard solution, according to step b) of the detection method of the present invention, measures the correction factor of pH to potential.
Using FeSO 4 、Fe 2 (SO 4 ) 3 And H 2 SO 4 Preparing a series of Fe ions with the total Fe ion concentration of 0.5mol/L 3+ The standard solutions had a pH of 0, 1 and 2, respectively, at a ratio of 0.5. The reference electrode was chosen to be Hg/Hg 2 SO 4 Electrode, working electrode is a glassy carbon electrode the detection device as described in example 1 was assembled, a standard solution was added to the detection cell, and the reference electrode and working electrode were connected to an electrochemical workstation. The actual potentials of the series of standard solutions were measured at 20 ℃ and 0.1MPa, respectively, and then fitted according to equation (4).
As a result, the pH-potential correction coefficient was 0.0040V (FIG. 3).
Example 4
This example illustrates for Fe 3+ /Fe 2+ The standard solution, according to step c) of the detection method of the present invention, measures the temperature coefficient and the pressure coefficient of the reference electrode.
Using FeSO 4 、Fe 2 (SO 4 ) 3 And H 2 SO 4 Preparing Fe with total Fe ion concentration of 0.5mol/L 3+ 0.5 and pH 0. The reference electrode was chosen to be Hg/Hg 2 SO 4 Electrode, working electrode, glassy carbon electrode the assay device as described in example 1 was assembled, standard solution was added to the assay cell, and reference was addedThe electrode and the working electrode are connected to an electrochemical workstation. Firstly, the pressure is controlled to be 0.1MPa, the actual potential of the standard solution is measured under the conditions of 20 ℃, 30 ℃, 40 ℃ and 50 ℃ in sequence, the potential of the reference electrode is calculated according to a formula (4) respectively, and then fitting is carried out according to a formula (5). Then, the temperature is controlled to be 20 ℃, the actual potential of the standard solution is measured under the conditions of the pressures of 0.1MPa, 0.2MPa and 0.3MPa in sequence, the potential of the reference electrode is calculated according to the formula (4) respectively, and then fitting is carried out according to the formula (6).
As a result, the temperature coefficient of the reference electrode was-0.00105V/K (FIG. 4), and the pressure coefficient was 0.00065V/MPa (FIG. 5).
Example 5
This example illustrates the measurement of Fe according to the detection method of the present invention 3+ /Fe 2+ And (4) valence state distribution of Fe ions in the solution to be detected.
Taking a group of 10 different Fe solutions to be detected, respectively measuring the pH and the actual potential of the 10 different Fe solutions to be detected under the conditions that the temperature is 20 ℃ and the pressure is 0.1MPa, and calculating the Fe of each solution according to a formula (8) 3+ Ratio of X h . Simultaneously, fe in each solution was measured separately using a potentiometric titrator 3+ And Fe 2+ Calculating Fe 3+ Ratio of X h ' the absolute error can be obtained by comparing the results obtained by the method of the present invention. The absolute error is calculated as follows:
absolute error = X h -X h ’
The results are shown in Table 1.
TABLE 1
It can be found that the absolute error of the detection method of the present invention is not more than ± 0.01.
Example 6
This example illustrates the on-line measurement of Fe according to the detection method of the present invention 3+ /Fe 2+ And (4) the valence state distribution of the Fe ions in the solution to be detected.
Using FeSO 4 And H 2 SO 4 Preparing a solution with the total Fe ion concentration of 0.5mol/L and the pH value of 0. The solution was placed on the positive side of an electrolytic cell for electrolytic oxidation, while the electrolytic cell was connected to the detection cell of the detection device described in example 1 using a circulation pump, and then a reference electrode and a working electrode were connected to an electrochemical workstation for Fe at 20 ℃ and 0.1MPa 3+ And (5) carrying out online detection on the ratio. Meanwhile, samples were taken every 30min and measured using an electrochemical titrator. The results are shown in FIG. 6, in which the broken line represents Fe calculated by dividing the amount of charge of the charge/discharge meter 3+ The solid line represents Fe calculated by the detection method of the present invention 3+ The percentage, square mark is Fe measured by potentiometric titrator 3+ The ratio of the components is.
It can be seen that the detection method of the present invention has good accuracy.
Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.
Claims (12)
1. A detection method of metal ion valence state distribution is characterized in that:
the detection method comprises the following steps:
a) Preparing a group of metal ion standard solutions I to be detected with the same total concentration, the same pH value and different valence state distributions, and performing concentration measurement at a temperature T 1 And pressure P 1 Measuring a valence state distribution-potential standard curve of the standard solution I under the condition;
b) Preparing a group of metal ions to be detected with the same total concentration, the same valence state distribution and different pH valuesStandard solution II, at temperature T 2 And pressure P 2 Measuring the pH-potential standard curve of the standard solution II under the condition;
c) Selecting standard solution III of metal ions to be detected with known total concentration, valence state distribution and pH value, and performing heat treatment at different temperatures T 3 And pressure P 3 Measuring the potential of the standard solution III under the condition, and measuring the correction coefficient of the temperature and the pressure to the potential;
d) Measuring the potential, pH, temperature and pressure of the actual solution to be measured, and calculating the valence state distribution of ions to be measured in the solution according to a formula (8) by combining the valence state distribution-potential standard curve given in the step a) and the pH-potential standard curve given in the step b) with the correction coefficient of the temperature and pressure to the potential given in the step c);
the metal ions to be detected are ion pairs consisting of two ions with different valence states of the same metal;
the valence distribution is the ratio of the higher valence metal ions in the ion pair to the total metal ion pair;
wherein, X h The ratio of the high valence state ions, namely the valence state distribution of the ions to be detected;
n is the number of electron transfer corresponding to half reaction; f is a Faraday constant;
phi' is the potential of the solution to be measured in step d);
φ 0 the standard electrode potential of the ions to be detected in the solution to be detected in the step d);
φ Ref (T, P) is the reference electrode potential under the temperature and pressure conditions of step d);
r is an ideal gas constant; t is temperature, and delta is a correction coefficient of pH to potential.
2. The method according to claim 1, wherein the metal ion valence state distribution is detected by:
the described to be measuredThe metal ion is selected from V 3+ /V 2+ 、VO 2+ /V 3+ 、VO 2 + /VO 2+ 、CrO 4 2- /Cr 3+ 、Cr 2 O 7 2- /Cr 3+ 、MnO 4 - /Mn 2+ Or Fe 3+ /Fe 2+ One kind of (1).
3. The method according to claim 1, wherein the distribution of valence states of the metal ions is:
the total concentration of the metal ions to be detected in the standard solution I in the step a) is selected from 0.01mol/L, 0.02mol/L, 0.05mol/L, 0.1mol/L, 0.2mol/L, 0.5mol/L, 1.0mol/L, 5.0mol/L or 10.0mol/L;
the total concentration of the metal ions to be detected in the standard solution II in the step b) is selected from 0.01mol/L, 0.02mol/L, 0.05mol/L, 0.1mol/L, 0.2mol/L, 0.5mol/L, 1.0mol/L, 5.0mol/L or 10.0mol/L;
the total concentration of the metal ions to be detected in the standard solution III in the step c) is selected from 0.01mol/L, 0.02mol/L, 0.05mol/L, 0.1mol/L, 0.2mol/L, 0.5mol/L, 1.0mol/L, 5.0mol/L or 10.0mol/L;
the total concentration of the metal ions to be detected in the actual solution to be detected in the step d) is 0.01 to 10mol/L.
4. The method according to claim 1, wherein the metal ion valence state distribution is detected by:
in the standard solution I in the step a), the valence state distribution is 0.05, 0.1, 0.25, 0.5, 0.75, 0.9 and 0.95;
in the standard solution II in the step b), the valence state distribution is selected from 0.05, 0.1, 0.25, 0.5, 0.75, 0.9 or 0.95;
in said standard solution III in step c), the valence state distribution is selected from 0.05, 0.1, 0.25, 0.5, 0.75, 0.9 or 0.95.
5. The method according to claim 1, wherein the distribution of valence states of the metal ions is:
in the standard solution I in the step a), the pH is selected from one of-1, 0, 1, 2, 3, 4, 5, 6 or 7;
in the standard solution II in the step b), the pH is selected from at least three of-1, 0, 1, 2, 3, 4, 5, 6 or 7;
in the standard solution III in step c), the pH is selected from one of-1, 0, 1, 2, 3, 4, 5, 6 or 7;
and d) in the actual solution to be measured in the step d), the pH is-1 to 7.
6. The method according to claim 1, wherein the metal ion valence state distribution is detected by:
in step a), the T 1 A residue from 0C, 10C, 20C, 30C, 40C, 50C, 60C, 70C, or 80C;
said P in step a) 1 Selected from 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa or 1.0MPa;
said T in step b) 2 A residue from 0C, 10C, 20C, 30C, 40C, 50C, 60C, 70C, or 80C;
said P in step b) 2 Selected from 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa or 1.0MPa;
t as described in step c) 3 (ii) at least three selected from 0C, 10C, 20C, 30C, 40C, 50C, 60C, 70C, or 80C;
p as described in step c) 3 At least three selected from 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa or 1.0MPa;
the temperature of the actual solution to be tested in the step d) is 0 to 80 ℃;
the pressure of the actual solution to be measured in the step d) is 0.1 to 1.0MPa.
7. The method for detecting the valence distribution of a metal ion according to any one of claims 1 to 6, wherein:
and measuring the valence state distribution of the metal ions to be detected by adopting the detection method, wherein the absolute error of the valence state distribution is not more than +/-0.01.
8. A detection device for detecting the distribution of valence states of metal ions, which is used in the detection method for the distribution of valence states of metal ions according to any one of claims 1 to 7.
9. The apparatus for detecting a valence state distribution of a metal ion according to claim 8, wherein:
the detection device includes: a detection cell, an electrochemical workstation; and a reference electrode, a working electrode, a temperature sensor, a pH sensor and a pressure sensor which are positioned in the detection cell;
the electrochemical workstation is electrically connected with the reference electrode and the working electrode and is used for obtaining the potentials of the standard solution I, the standard solution II, the standard solution III and the solution to be detected;
the temperature sensor is used for obtaining the temperatures of the standard solution I, the standard solution II, the standard solution III and the solution to be detected;
the pH sensor is used for obtaining the pH values of the standard solution I, the standard solution II, the standard solution III and the solution to be detected;
the pressure sensor is used for obtaining the pressures of the standard solution I, the standard solution II, the standard solution III and the solution to be detected.
10. The apparatus according to claim 9, wherein:
the reference electrode is selected from Hg/Hg 2 SO 4 Electrode, hg/Hg 2 Cl 2 One of an electrode or an Ag/AgCl electrode;
the working electrode is selected from one of a glassy carbon electrode, a graphite electrode, a gold electrode, a platinum electrode or a silver electrode.
11. The apparatus for detecting a valence state distribution of a metal ion according to claim 9, wherein:
a liquid inlet is formed in the lower part of the side wall of the detection pool; the upper portion of the pool lateral wall of the detection pool is provided with a liquid outlet which can be used for on-line detection.
12. The detection device according to any one of claims 8 to 11, wherein:
and measuring the valence state distribution of the metal ions to be detected by adopting the detection device, wherein the absolute error of the valence state distribution is not more than +/-0.01.
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