A kind of detection method of nickel-containing ammonium fluoride solution

Abstract

The invention discloses a detection method for a nickel-containing ammonium fluoride solution, comprising the following steps: S1, configuring five nickel-containing ammonium fluoride standard solutions with different nickel contents and the same ammonium fluoride content; S2, detecting the nickel concentration and ammonium fluoride concentration of the five nickel-containing ammonium fluoride standard solutions; S3, establishing a linear fitting curve with the nickel concentration detection values ​​and ammonium fluoride concentration detection values ​​of the five nickel-containing ammonium fluoride standard solutions, and determining a calibration relationship; S4, detecting the nickel concentration of the nickel-containing ammonium fluoride solution to be tested, if the nickel concentration is ≤1.5wt%, directly entering step S5, if the nickel concentration is >1.5wt%, adding a nickel precipitant to the nickel-containing ammonium fluoride solution to be tested, and entering step S5 after precipitation treatment; S5, detecting the ammonium fluoride concentration of the nickel-containing ammonium fluoride solution to be tested, and then substituting it into the calibration relationship for calibration to obtain the accurate value of the ammonium fluoride concentration. The detection method of the present invention is simple to operate, short in test time, high in efficiency, high in repeatability of test results, efficient in test mode, and has wide practicability.

Description

Technical Field

[0001] The invention relates to the technical field of quantitative detection, and in particular to a detection method for a nickel-containing ammonium fluoride solution. Background Art

[0002] Nickel-containing etching waste liquid mainly comes from the pickling and rinsing of plated parts during the pretreatment of metal plated parts, as well as the rinse water after plating in some acid electroplating tanks such as acid copper plating and nickel plating. The characteristics of nickel-containing etching waste liquid are that the nickel content is relatively high between 1 and 5%, and the solution also contains 8 to 15% fluoride ions and 7 to 10% ammonium ions. Nickel-containing etching waste liquid needs to be treated. Common treatment methods focus on resin adsorption, membrane separation, electrolysis and chemical precipitation.

[0003] During the treatment of nickel-containing etching waste liquid, the ammonium fluoride content needs to be tested. At present, the industry generally determines the ammonium fluoride content by acid-base titration. The pH titration end point is around pH 7. At this time, if the Ni content in the solution is higher than 1.5%, the titration data error is large. The reason is that nickel will produce nickel-ammonium complex in an environment containing ammonium radicals at a pH of around 7, thereby affecting the combination of OH- and ammonium fluoride and causing data deviation. Summary of the invention

[0004] The main purpose of the invention is to provide a detection method for a nickel-containing ammonium fluoride solution capable of eliminating nickel interference.

[0005] To achieve the above object, the present invention provides a method for detecting a nickel-containing ammonium fluoride solution, comprising the following steps:

[0006] S1. Preparation of standard solution

[0007] Prepare five nickel-containing ammonium fluoride standard solutions with different nickel contents and the same ammonium fluoride content, and the nickel contents of the five nickel-containing ammonium fluoride standard solutions are all below 1.5wt%;

[0008] S2. Detection of standard solution

[0009] Detect the nickel concentration and ammonium fluoride concentration of five nickel-containing ammonium fluoride standard solutions;

[0010] S3. Establishment of calibration relationship

[0011] A linear fitting curve is established based on the nickel concentration detection values ​​and the ammonium fluoride concentration detection values ​​of five nickel-containing ammonium fluoride standard solutions to determine the calibration relationship;

[0012] S4. Treatment of the nickel-containing ammonium fluoride solution to be tested

[0013] Detecting the nickel concentration of the nickel-containing ammonium fluoride solution to be tested, if the nickel concentration is ≤1.5wt%, directly proceeding to step S5, if the nickel concentration is >1.5wt%, adding a nickel precipitant to the nickel-containing ammonium fluoride solution to be tested, and proceeding to step S5 after precipitation treatment;

[0014] S5. Detection and calibration of the nickel-containing ammonium fluoride solution to be tested

[0015] The ammonium fluoride concentration of the nickel-containing ammonium fluoride solution to be tested is detected, and then substituted into the calibration relationship for calibration to obtain the ammonium fluoride concentration calibration value.

[0016] Furthermore, in step S1, the ammonium fluoride content of the prepared nickel-containing ammonium fluoride standard solution does not exceed 20 wt%.

[0017] Furthermore, in step S2, the nickel concentration is detected by EDTA titration method, and the ammonium fluoride concentration is detected by acid-base titration method.

[0018] Further, in step S3, the linear fitting curve takes the nickel concentration detection value as the horizontal coordinate and |ammonium fluoride concentration detection value-ammonium fluoride concentration standard value| as the vertical coordinate.

[0019] Furthermore, in step S4, the addition of the nickel precipitant is configured to reduce the nickel concentration of the nickel-containing ammonium fluoride solution to be tested to below 1.5 wt%.

[0020] Furthermore, in step S4, the nickel precipitant is sodium dithioaminocyanurate (TDC), the molar ratio of nickel to sodium dithioaminocyanurate is 3:2-2.4, and the precipitation treatment condition is precipitation at room temperature for 10 minutes.

[0021] The beneficial effects of the present invention are embodied in:

[0022] The invention establishes a linear fitting curve related to the ammonium fluoride content with a nickel content of less than 1.5wt% (the nickel content within this range does not affect the titration detection of ammonium fluoride), determines a calibration relationship, and then determines whether to directly perform the detection of ammonium fluoride according to the nickel concentration range when detecting the nickel-containing ammonium fluoride solution to be detected. When the nickel concentration is greater than 1.5wt%, the nickel concentration is reduced to less than 1.5wt% by a precipitation method before the detection is performed, so that the calibration value of ammonium fluoride can be obtained according to the previous calibration relationship, the interference of nickel is eliminated, and the detection accuracy is improved.

[0023] The detection method of the present invention is simple to operate, has a short test time, high efficiency, high repeatability of test results, and an efficient test method, and has wide practicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the linear fitting curve diagram of Example 1.

[0025] Figure 2 It is the linear fitting curve diagram of Example 2.

[0026] Figure 3 It is the linear fitting curve diagram of Example 3.

[0027] Figure 4 It is the linear fitting curve diagram of comparative example 1. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0029] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods; unless otherwise specified, the methods used in the embodiments of the present invention are methods known to those skilled in the art. Among them, the detection methods of nickel concentration and ammonium fluoride concentration are as follows:

[0030] The nickel concentration is tested by EDTA titration method, with reference to HG / T 3734 industrial nickel fluoride, as follows:

[0031] In an ammonia-ammonium chloride buffer solution, nickel is titrated with EDTA standard titration solution using ammonium violaceum as an indicator.

[0032] Reagents: (1) Ammonia water; (2) Standard titration solution of disodium ethylenediaminetetraacetate: c(EDTA) about 0.02 mol / L; (3) Murexide indicator; (4) Ammonia-ammonium chloride buffer solution A (PH ≈ 10);

[0033] Use a pipette to transfer 10 mL of the standard solution into a 250 mL conical flask, add 80 mL of water, 3 drops of ammonia water, 10 mL of ammonia-ammonium chloride buffer solution A, and 0.2 g of ammonium violaceum indicator, and titrate with EDTA standard titration solution. When near the end point, slowly titrate until the solution turns red-purple.

[0034] The mass fraction of nickel (Ni) Ni The value is expressed in %, calculated according to formula (1):

[0035]

[0036] V1——The volume of EDTA standard titration solution consumed by titrating the test solution, in milliliters (mL);

[0037] c——The exact value of the concentration of the EDTA standard titration solution, in moles per liter (mol / L);

[0038] M1——the numerical value of the molar mass of nickel in grams per mole (g / mol) (M=58.69);

[0039] m1——the numerical value of the sample mass, in grams (g).

[0040] The concentration of ammonium fluoride is tested by acid-base titration, with reference to GB 28653 industrial ammonium fluoride, as follows:

[0041] Add formaldehyde to react with ammonium ions to generate hexamethylenetetramine and release acid. Use phenolphthalein as an indicator and titrate with sodium hydroxide standard titration solution to obtain the ammonium fluoride content.

[0042] Reagents: (1) Neutral formaldehyde solution: 1+1; (2) Sodium hydroxide standard titration solution: c(NaOH)≈0.5 mol / L; (3) Phenolphthalein indicator solution: 10 g / L;

[0043] In a plastic conical flask, weigh about 2.5g of sample, add 20ml of water, add 40ml of neutral formaldehyde, shake well, let stand for 30min, add 2 drops of phenolphthalein, and titrate with sodium hydroxide until the solution turns pink and keep it for 30s without fading.

[0044] The mass fraction of ammonium fluoride (NHF) ω NHF The value is expressed in %, calculated according to formula (2):

[0045]

[0046] V2——The volume of sodium hydroxide standard titration solution consumed by titrating the test solution, in milliliters (mL);

[0047] c2——The exact value of the concentration of the sodium hydroxide standard titration solution, in moles per liter (mol / L);

[0048] M2——the numerical value of the molar mass of ammonium fluoride in grams per mole (g / mol) (M=37.04);

[0049] m1——the numerical value of the sample mass, in grams (g).

[0050] Example 1

[0051] Detection of nickel-containing ammonium fluoride solution

[0052] The steps are as follows:

[0053] S1. Preparation of standard solution

[0054] Five nickel-containing ammonium fluoride standard solutions with different nickel contents and the same ammonium fluoride content were prepared, and the specific concentration standard values ​​are shown in Table 1;

[0055] S2. Detection of standard solution

[0056] The nickel concentration and ammonium fluoride concentration of five nickel-containing ammonium fluoride standard solutions were detected by EDTA titration and acid-base titration. The specific detection values ​​are shown in Table 1.

[0057] Table 1

[0058]

[0059] S3. Establishment of calibration relationship

[0060] The ammonium fluoride calibration values ​​of the five nickel-containing ammonium fluoride standard solutions were calculated, where ammonium fluoride calibration value = |ammonium fluoride concentration detection value - ammonium fluoride concentration standard value|. The results are shown in Table 1.

[0061] The nickel concentration detection values ​​of the five nickel-containing ammonium fluoride standard solutions were used as the horizontal axis, and the ammonium fluoride calibration values ​​were used as the vertical axis. Linear fitting was performed using Excel software, see Figure 1 , and the linear fitting curve y = 0.896x-0.008, R 2 =0.9991, and then the calibration relationship is obtained by inverse deduction based on the fitting: ω Ni is the nickel concentration detection value.

[0062] S4. Treatment of the nickel-containing ammonium fluoride solution to be tested

[0063] A solution having an ammonium fluoride concentration of 11.17 wt % and a nickel concentration of 2.2 wt % is prepared as the nickel-containing ammonium fluoride solution to be tested;

[0064] The nickel concentration of the nickel-containing ammonium fluoride solution to be tested was 2.2wt% by EDTA titration method, which was higher than 1.5wt%. Then sodium dithioaminocyanurate was added at a molar ratio of nickel: sodium dithioaminocyanurate = 3:2, and precipitation was performed at room temperature for 10 minutes.

[0065] S5. Detection and calibration of the nickel-containing ammonium fluoride solution to be tested

[0066] The nickel-containing ammonium fluoride solution to be tested after the treatment in step S4 is filtered, and then the nickel concentration is detected by EDTA titration method to be 0.5wt%, and the ammonium fluoride concentration is detected by acid-base titration method to be 11.60wt%. Substituting into the above calibration relationship, the ammonium fluoride concentration calibration value is 11.16wt%, and the error is less than 0.2%.

[0067] Example 2

[0068] Detection of nickel-containing ammonium fluoride solution

[0069] The steps are as follows:

[0070] S1. Preparation of standard solution

[0071] Five nickel-containing ammonium fluoride standard solutions with different nickel contents and the same ammonium fluoride content were prepared, and the specific concentration standard values ​​are shown in Table 2;

[0072] S2. Detection of standard solution

[0073] The nickel concentration and ammonium fluoride concentration of five nickel-containing ammonium fluoride standard solutions were detected by EDTA titration and acid-base titration. The specific detection values ​​are shown in Table 2.

[0074] Table 2

[0075]

[0076] S3. Establishment of calibration relationship

[0077] The ammonium fluoride calibration values ​​of the five nickel-containing ammonium fluoride standard solutions were calculated, where ammonium fluoride calibration value = |ammonium fluoride concentration detection value - ammonium fluoride concentration standard value|. The results are shown in Table 2.

[0078] The nickel concentration detection values ​​of the five nickel-containing ammonium fluoride standard solutions were used as the horizontal axis, and the ammonium fluoride calibration values ​​were used as the vertical axis. Linear fitting was performed using Excel software, see Figure 2 , and the linear fitting curve y = 0.8371x-0.0144, R 2 =0.9991, and then the calibration relationship is obtained by inverse deduction based on the fitting: ω Ni is the nickel concentration detection value.

[0079] S4. Treatment of the nickel-containing ammonium fluoride solution to be tested

[0080] A solution having an ammonium fluoride concentration of 11.30 wt % and a nickel concentration of 2.5 wt % is prepared as the nickel-containing ammonium fluoride solution to be tested;

[0081] The nickel concentration of the nickel-containing ammonium fluoride solution to be tested is 2.5wt% by EDTA titration method, which is higher than 1.5wt%. Then sodium dithioaminocyanurate is added at a molar ratio of nickel: sodium dithioaminocyanurate = 3:2.4, and precipitation is performed at room temperature for 10 minutes.

[0082] S5. Detection and calibration of the nickel-containing ammonium fluoride solution to be tested

[0083] The nickel-containing ammonium fluoride solution to be tested after the treatment in step S4 is filtered, and then the nickel concentration is detected by EDTA titration method to be 0.9wt%, and the ammonium fluoride concentration is detected by acid-base titration method to be 12.02wt%. Substituting into the above calibration relationship, the ammonium fluoride concentration calibration value is 11.28wt%, and the error is less than 0.2%.

[0084] Example 3

[0085] Detection of nickel-containing ammonium fluoride solution

[0086] The steps are as follows:

[0087] S1. Preparation of standard solution

[0088] Five nickel-containing ammonium fluoride standard solutions with different nickel contents and the same ammonium fluoride content were prepared, and the specific concentration standard values ​​are shown in Table 3;

[0089] S2. Detection of standard solution

[0090] The nickel concentration and ammonium fluoride concentration of five nickel-containing ammonium fluoride standard solutions were detected by EDTA titration and acid-base titration. The specific detection values ​​are shown in Table 3.

[0091] Table 3

[0092]

[0093] S3. Establishment of calibration relationship

[0094] The ammonium fluoride calibration values ​​of the five nickel-containing ammonium fluoride standard solutions were calculated, where ammonium fluoride calibration value = |ammonium fluoride concentration detection value - ammonium fluoride concentration standard value|. The results are shown in Table 3.

[0095] The nickel concentration detection values ​​of the five nickel-containing ammonium fluoride standard solutions were used as the horizontal axis, and the ammonium fluoride calibration values ​​were used as the vertical axis. Linear fitting was performed using Excel software, see Figure 3 , and the linear fitting curve y = 0.4728x-0.003, R 2 =0.999, and then the calibration relationship is obtained by back-calculation based on the fitting: ω Ni is the nickel concentration detection value.

[0096] S4. Treatment of the nickel-containing ammonium fluoride solution to be tested

[0097] A solution having an ammonium fluoride concentration of 9.41 wt % and a nickel concentration of 1.6 wt % is prepared as the nickel-containing ammonium fluoride solution to be tested;

[0098] The nickel concentration of the nickel-containing ammonium fluoride solution to be tested was 1.6 wt % by EDTA titration method, which was higher than 1.5 wt %. Then sodium dithioaminocyanurate was added at a molar ratio of nickel: sodium dithioaminocyanurate = 3:2.1, and precipitation was performed at room temperature for 10 min.

[0099] S5. Detection and calibration of the nickel-containing ammonium fluoride solution to be tested

[0100] The nickel-containing ammonium fluoride solution to be tested after the treatment in step S4 is filtered, and then the nickel concentration is detected by EDTA titration method to be 0.6wt%, and the ammonium fluoride concentration is detected by acid-base titration method to be 9.71wt%. Substituting into the above calibration relationship, the ammonium fluoride concentration calibration value is 9.43wt%, and the error is less than 0.2%.

[0101] Comparative Example 1

[0102] Detection of nickel-containing ammonium fluoride solution

[0103] The steps are as follows:

[0104] S1. Preparation of standard solution

[0105] Five nickel-containing ammonium fluoride standard solutions with different nickel contents and the same ammonium fluoride content were prepared, and the specific concentration standard values ​​are shown in Table 4;

[0106] S2. Detection of standard solution

[0107] The nickel concentration and ammonium fluoride concentration of five nickel-containing ammonium fluoride standard solutions were detected by EDTA titration and acid-base titration. The specific detection values ​​are shown in Table 4.

[0108] Table 4

[0109]

[0110] S3. Establishment of calibration relationship

[0111] The ammonium fluoride calibration values ​​of the five nickel-containing ammonium fluoride standard solutions were calculated, where ammonium fluoride calibration value = |ammonium fluoride concentration detection value - ammonium fluoride concentration standard value|. The results are shown in Table 4.

[0112] The nickel concentration detection values ​​of the five nickel-containing ammonium fluoride standard solutions were used as the horizontal axis, and the ammonium fluoride calibration values ​​were used as the vertical axis. Linear fitting was performed using Excel software, see Figure 4 , its fitting error R 2 =0.9267, which is unable to reach the target of 0.999. The nickel content and the amount of sodium hydroxide used are not in a linear relationship, so this method cannot be used for calibration calculation.

[0113] Comparative Example 2

[0114] Detection of nickel-containing ammonium fluoride solution

[0115] This comparative example is operated according to the method of Example 3, except that sodium dithioaminocyanurate is not used to precipitate nickel ions. The nickel concentration is directly detected by EDTA titration method and is 1.6wt%. The ammonium fluoride concentration is detected by acid-base titration method and is 10.26wt%. The calibration relationship is used to obtain the ammonium fluoride concentration calibration value of 9.51wt%, with an error of 1.06%, which is relatively large.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting a nickel-containing ammonium fluoride solution, characterized in that: The following steps are involved: S1. Preparation of standard solution Prepare five nickel-containing ammonium fluoride standard solutions with different nickel contents and the same ammonium fluoride content, and the nickel contents of the five nickel-containing ammonium fluoride standard solutions are all below 1.5wt%; S2. Detection of standard solution Detect the nickel concentration and ammonium fluoride concentration of five nickel-containing ammonium fluoride standard solutions; S3. Establishment of calibration relationship A linear fitting curve is established based on the nickel concentration detection values ​​and the ammonium fluoride concentration detection values ​​of five nickel-containing ammonium fluoride standard solutions to determine the calibration relationship; S4. Treatment of the nickel-containing ammonium fluoride solution to be tested Detecting the nickel concentration of the nickel-containing ammonium fluoride solution to be tested, if the nickel concentration is ≤1.5wt%, directly proceeding to step S5, if the nickel concentration is >1.5wt%, adding a nickel precipitant to the nickel-containing ammonium fluoride solution to be tested, and proceeding to step S5 after precipitation treatment; S5. Detection and calibration of the nickel-containing ammonium fluoride solution to be tested The ammonium fluoride concentration of the nickel-containing ammonium fluoride solution to be tested is detected, and then substituted into the calibration relationship for calibration to obtain the ammonium fluoride concentration calibration value.

2. The method for detecting a nickel-containing ammonium fluoride solution according to claim 1, wherein: In step S1, the ammonium fluoride content of the prepared nickel-containing ammonium fluoride standard solution does not exceed 20wt%.

3. The method for detecting the nickel-containing ammonium fluoride solution according to claim 1 or 2, characterized in that: In step S2, the nickel concentration is detected by EDTA titration method, and the ammonium fluoride concentration is detected by acid-base titration method.

4. The method for detecting the nickel-containing ammonium fluoride solution according to claim 1 or 2, wherein: In step S3, the linear fitting curve takes the nickel concentration detection value as the horizontal coordinate and |ammonium fluoride concentration detection value-ammonium fluoride concentration standard value| as the vertical coordinate.

5. The method for detecting the nickel-containing ammonium fluoride solution according to claim 1 or 2, characterized in that: In step S4, the nickel precipitant is added to reduce the nickel concentration of the nickel-containing ammonium fluoride solution to be tested to below 1.5 wt %.

6. The method for detecting the nickel-containing ammonium fluoride solution according to claim 5, characterized in that: In step S4, the nickel precipitant is sodium dithioaminocyanurate, the molar ratio of nickel to sodium dithioaminocyanurate is 3:2-2.4, and the precipitation treatment condition is precipitation at room temperature for 10 minutes.

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