CN113533626A - Method for measuring chloride ion content in cold-rolled chromium-containing sludge - Google Patents
Method for measuring chloride ion content in cold-rolled chromium-containing sludge Download PDFInfo
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- CN113533626A CN113533626A CN202110715854.8A CN202110715854A CN113533626A CN 113533626 A CN113533626 A CN 113533626A CN 202110715854 A CN202110715854 A CN 202110715854A CN 113533626 A CN113533626 A CN 113533626A
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- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title claims abstract description 54
- 229910052804 chromium Inorganic materials 0.000 title claims abstract description 54
- 239000011651 chromium Substances 0.000 title claims abstract description 54
- 239000010802 sludge Substances 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 51
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 title claims abstract description 39
- 238000004448 titration Methods 0.000 claims abstract description 36
- 238000001035 drying Methods 0.000 claims abstract description 30
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 20
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 17
- 238000001914 filtration Methods 0.000 claims abstract description 17
- 238000000227 grinding Methods 0.000 claims abstract description 17
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 16
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 16
- 239000000706 filtrate Substances 0.000 claims abstract description 14
- 238000010304 firing Methods 0.000 claims abstract description 12
- 238000012360 testing method Methods 0.000 claims abstract description 11
- 238000011282 treatment Methods 0.000 claims abstract description 10
- 238000001556 precipitation Methods 0.000 claims abstract description 8
- 239000007788 liquid Substances 0.000 claims abstract description 7
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 claims abstract description 4
- 238000007873 sieving Methods 0.000 claims abstract description 4
- 230000020477 pH reduction Effects 0.000 claims abstract description 3
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 38
- 229910052573 porcelain Inorganic materials 0.000 claims description 19
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 19
- 238000005303 weighing Methods 0.000 claims description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- 238000005406 washing Methods 0.000 claims description 14
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 12
- 230000001376 precipitating effect Effects 0.000 claims description 7
- 229910021529 ammonia Inorganic materials 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 238000009835 boiling Methods 0.000 claims description 5
- 238000009736 wetting Methods 0.000 claims description 5
- 125000001309 chloro group Chemical group Cl* 0.000 claims description 3
- 230000001502 supplementing effect Effects 0.000 claims description 2
- 238000005097 cold rolling Methods 0.000 claims 8
- 239000000243 solution Substances 0.000 abstract description 39
- 239000002244 precipitate Substances 0.000 abstract description 10
- 239000012490 blank solution Substances 0.000 abstract description 5
- VQWFNAGFNGABOH-UHFFFAOYSA-K chromium(iii) hydroxide Chemical compound [OH-].[OH-].[OH-].[Cr+3] VQWFNAGFNGABOH-UHFFFAOYSA-K 0.000 abstract description 3
- 238000005008 domestic process Methods 0.000 abstract 1
- 238000012544 monitoring process Methods 0.000 abstract 1
- 239000000523 sample Substances 0.000 description 52
- 238000001514 detection method Methods 0.000 description 13
- 238000005259 measurement Methods 0.000 description 6
- 239000000460 chlorine Substances 0.000 description 5
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 4
- 229910052801 chlorine Inorganic materials 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- 239000002253 acid Substances 0.000 description 3
- OJKANDGLELGDHV-UHFFFAOYSA-N disilver;dioxido(dioxo)chromium Chemical compound [Ag+].[Ag+].[O-][Cr]([O-])(=O)=O OJKANDGLELGDHV-UHFFFAOYSA-N 0.000 description 3
- 239000002910 solid waste Substances 0.000 description 3
- 229910021642 ultra pure water Inorganic materials 0.000 description 3
- 239000012498 ultrapure water Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 238000002372 labelling Methods 0.000 description 2
- 238000012216 screening Methods 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical class [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229940075397 calomel Drugs 0.000 description 1
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- UOUJSJZBMCDAEU-UHFFFAOYSA-N chromium(3+);oxygen(2-) Chemical class [O-2].[O-2].[O-2].[Cr+3].[Cr+3] UOUJSJZBMCDAEU-UHFFFAOYSA-N 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical compound Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000004255 ion exchange chromatography Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000006101 laboratory sample Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 238000003918 potentiometric titration Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- -1 silver ions Chemical class 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000004879 turbidimetry Methods 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/16—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using titration
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/34—Purifying; Cleaning
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/44—Sample treatment involving radiation, e.g. heat
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
- G01N2001/2866—Grinding or homogeneising
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- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Molecular Biology (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
- Treatment Of Sludge (AREA)
Abstract
The invention discloses a method for measuring the content of chloride ions in cold-rolled chromium-containing sludge, which comprises the following steps: (1) drying and grinding: drying the sample in a drying oven, grinding and sieving; (2) high-temperature firing: burning in a high temperature furnace; (3) dissolving and reducing: adding dilute nitric acid to dissolve a sample, and adding hydrogen peroxide to reduce hexavalent chromium; (4) and (3) precipitation and filtration: adding dilute ammonia water to generate chromium hydroxide precipitate, and filtering; (5) acidifying: adding nitric acid into the filtrate for acidification to obtain a solution to be detected; (6) detecting by a potentiometric titrator: titrating the solution to be tested, and carrying out blank test; (7) and (3) calculating the result: and calculating the content of chloride ions in the sample according to the volume of the titration liquid consumed by the solution to be detected and the blank solution. The method provided by the invention fills the technical blank of the domestic method for measuring the content of chloride ions in the cold-rolled chromium-containing sludge, is easy to operate and high in accuracy, and has guiding significance for monitoring the content of chloride ions in the chromium-containing sludge during subsequent treatment.
Description
Technical Field
The application relates to the technical field of chemical analysis, in particular to a method for measuring the content of chloride ions in cold-rolled chromium-containing sludge.
Background
The cold-rolled chromium-containing sludge is solid waste generated after cold-rolled chromium-containing wastewater is subjected to a series of treatments and filter pressing by a filter press. The main components are chromium oxide and organic matter, and small amount of impurity elements such as copper, iron, zinc, nickel heavy metal and halogen (mainly chloride ion). In order to respond to the national policy of fully recycling solid wastes and other resources, steel enterprises often use chromium-containing sludge as a smelting ingredient for metal smelting to achieve the purpose of reducing the cost. Therefore, the accurate detection of the elements in the chromium-containing sludge has important guiding significance for the subsequent treatment of the chromium-containing sludge, and particularly, the determination of the chloride ions provides an important reference basis for preventing the sludge from contacting equipment and the corrosion of a flue gas pipeline. However, no relevant method exists for measuring the content of chloride ions in the chromium-containing sludge at present, so that the establishment of the method for measuring the content of chloride ions in the chromium-containing sludge has important practical significance.
A common method for measuring chloride ions is a turbidimetry method, but the operation steps are complex and tedious and the detection error is large; the ion chromatography is also adopted to detect chloride ions, but a chromatographic column used in the operation is extremely easy to damage in an acid solution, and the price of an instrument is relatively high, so that the detection means cannot be popularized in most enterprises. In recent years, the method for detecting chloride ions by a potentiometric titrator is mature day by day, and the detection principle is as follows: the silver electrode is used as an indicating electrode, a calomel electrode of saturated sodium chloride is used as a reference electrode, silver nitrate is used as a titration solution, the potential of the indicating electrode changes in the titration process, and the chloride ion content is calculated through the volume number of the consumed silver nitrate at the titration end point. The method has simple operation and high accuracy.
The cold-rolled chromium-containing sludge contains a large amount of chromium oxides and organic matters, if the cold-rolled chromium-containing sludge is detected by a potentiometric titrator, the sensitivity of an electrode is reduced by organic insoluble substances in a solution, so that the titration end point of the titrator is not obvious, and chromate in the solution is easy to react with silver ions to generate silver chromate precipitate, so that the accuracy of the titration result is influenced. The method comprises the steps of burning a sample at a high temperature to remove organic matters, dissolving the organic matters in acid, adding dilute ammonia water to generate chromium hydroxide precipitate, filtering the precipitate, and detecting the content of chloride ions in filtrate in a potentiometric titrator. The method not only eliminates the interference of organic matters and the generated silver chromate precipitate on the detection process, but also improves the accuracy of the detection result, has simple and quick operation, and can be widely applied to the daily detection of the chloride ions in the chromium-containing sludge.
Disclosure of Invention
The invention aims to provide a method for measuring the content of chloride ions in cold-rolled chromium-containing sludge, so as to overcome the defects in the prior art.
In order to achieve the purpose, the invention provides the following technical scheme: a method for measuring the content of chloride ions in cold-rolled chromium-containing sludge comprises the following steps:
step 1: drying and grinding: taking back the sample on site, drying in a drying box, grinding by a vibration mill, and sieving;
step 2: high-temperature firing: weighing the dried and ground sample, placing the sample in a porcelain boat which is dried in advance to constant weight, placing the porcelain boat in a high-temperature furnace for burning, and calculating a loss on ignition coefficient Lc;
and step 3: dissolving and reducing: weighing a sample, wetting the sample with 1-2 mL of water, adding 10-20 mL of dilute nitric acid for dissolving, and slowly dropwise adding 1-2 mL of hydrogen peroxide for reducing hexavalent chromium;
and 4, step 4: and (3) precipitation and filtration: adding water into the solution, boiling, slowly adding 30-50 mL of dilute ammonia water until the solution generates a slight ammonia smell, supplementing 3-5 mL of dilute ammonia water, standing for a period of time, filtering the precipitate, washing the container and the precipitate for several times, and recovering the filtrate and the washing liquid into a beaker;
and 5: acidifying: adding 10mL of dilute nitric acid into the filtrate for acidification to obtain a solution to be detected;
step 6: detecting by an instrument: titrating the solution to be tested in the step 5 by using a silver nitrate standard titration solution on a potentiometric titrator, and recording the titration volume V1Recording the titration volume V along with the blank test0；
And 7: and (3) calculating the result: the calculation formula of the content of chloride ions in the chromium-containing sludge is as follows:
in the formula:
ω(Cl-) -chloride ion content,%, in the sample;
c, concentration of silver nitrate standard titration solution, mol/L;
V1-volume of silver nitrate standard titration solution consumed in titrating the sample, mL;
V0-volume of silver nitrate standard titration solution consumed in titrating the blank, mL;
lc-loss on ignition coefficient of the sample;
m-weighing the mass of the sample, g;
35.45-molar mass of Cl atoms, g/mol.
Preferably, in step 1, the drying and grinding process includes: the drying temperature of the drying oven is 105-110 ℃, and the drying time is 2 h; the vibration grinding time is 60-80 s, and the granularity of the metal mesh screen is 120 meshes.
Preferably, in step 2, the high-temperature burning process includes: weighing 1.0000-2.0000 g of sample, wherein the ignition temperature of the high-temperature furnace is 750-850 ℃, and the ignition time is 1.5-2 h.
Preferably, in the step 2, the calculation formula of the loss on ignition coefficient Lc is as follows:
in the formula:
m1weighing the mass g of the sample before firing treatment;
m2-drying the treated porcelain boat mass, g;
m3the combined amount of the porcelain boat and the sample after firing treatment, g;
lc-loss on ignition coefficient of the sample.
Preferably, in the step 3, the weight of the weighed sample is 0.2000-0.3000 g.
Preferably, in said step 3The concentration of the nitric acid before diluted nitric acid is 1.42g/cm3The concentration of the hydrogen peroxide is 1.13g/cm3。
Preferably, in the step 4, the concentration of the ammonia water before the diluted ammonia water is 0.91g/cm3。
Preferably, in step 4, the precipitation and filtration process includes: standing for 5-10 min, filtering with slow quantitative filter paper, washing the container and precipitating for at least 3 times, and recovering filtrate and washing liquid in a beaker with a volume of 150 mL.
Preferably, in the steps 3 and 5, the volume fraction of the dilute nitric acid is 50%.
Preferably, in the step 4, the volume fraction of the dilute ammonia water is 50%.
Preferably, in the step 6, the concentration of the silver nitrate standard titration solution is 0.50-1.00 mol/L.
The invention has the beneficial effects that:
(1) the invention adopts a high-temperature ignition method to remove organic matters in the cold-rolled chromium-containing sludge, adds hydrogen peroxide to reduce hexavalent chromium after acid dissolution, adds dilute ammonia water to generate chromium hydroxide precipitate, and precipitates and filters to obtain a solution to be detected, thereby eliminating the interference of the organic matters and the generated silver chromate precipitate on the detection of chloride ions.
(2) The method adopts a potentiometric titration method to measure the content of chloride ions in the cold-rolled chromium-containing sludge, and directly calculates the content of the chloride ions by the volume number of silver nitrate consumed at the end point of titration after interference is eliminated. The method has simple operation and high accuracy.
(3) The method fills the technical blank of analyzing the content of chloride ions in the domestic cold-rolled chromium-containing sludge, and has guiding significance for controlling and detecting the content of the chloride ions in the cold-rolled chromium-containing sludge and other solid wastes during subsequent treatment.
Detailed Description
Technical solutions in the embodiments of the present invention will be described in detail below, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The invention adopts the following instruments and reagents in the following method:
the instrument equipment comprises: automatic potentiometric titrators (model ZDJ-4A, shanghai thunder magnetic); high temperature furnace (type N31/H, Naberterm, Germany); a vibration sample grinding machine (ZHM-1A, Beijing Zhonghe) electric heating air blast drying box (FT101A (S) P-3 type, Zhenjiang Fengtai laboratory sample preparation equipment Co., Ltd.); electronic balance (XP204, mettler-toledo); ultra pure water apparatus (Millipore, USA).
All reagents are superior pure: nitric acid (1.42 g/cm)3) (ii) a Hydrogen peroxide (1.13 g/cm)3) (ii) a Ammonia (0.91 g/cm)3). All the test instruments are used after being soaked in nitric acid with the volume fraction of 5% for 24 hours and then rinsed with ultrapure water for three times. The pure water is ultrapure water.
Example 1
The specific implementation steps are as follows:
(1) drying and grinding: taking a chromium-containing sludge sample No. 1 back on site, placing the chromium-containing sludge sample in a drying box, drying the chromium-containing sludge sample for 2 hours at 110 ℃, grinding the dried chromium-containing sludge sample for 60 seconds in a vibration mill, and screening the chromium-containing sludge sample with a 120-mesh metal mesh screen;
(2) high-temperature firing: weighing 1.0000g (accurate to 0.0001g) of the sample obtained in the step (1), putting the sample into a porcelain boat which is dried in advance to constant weight, putting the porcelain boat into a high-temperature furnace, burning the porcelain boat for 1.5h at 750 ℃, and calculating a loss on ignition coefficient Lc;
(3) dissolving and reducing: weighing 0.2000g of the sample obtained in the step (2), wetting the sample with 1mL of water, adding 10mL of 50% dilute nitric acid for dissolving, and slowly dropwise adding 1mL of hydrogen peroxide solution;
(4) and (3) precipitation and filtration: adding 50mL of water into the solution, boiling, slowly adding 40mL of 50% diluted ammonia water until the solution generates a slight ammonia smell, then adding 5mL of water, standing for 5min, filtering by using slow quantitative filter paper, washing the container with water and precipitating for not less than 3 times, and recovering the filtrate and the washing liquid into a 150mL beaker;
(5) acidifying: adding 10mL of 50% dilute nitric acid into the filtrate to obtain a solution to be detected;
(6) detecting by an instrument: at the potential of the dropTitrating the solution to be tested in the step (5) by using 0.5mol/L silver nitrate standard titration solution on a calibrator, and recording the titration volume V1Recording the titration volume V along with the blank test0See table 1;
TABLE 11 titration volumes of solutions to be tested and blank solutions of chromium-containing sludge samples
(7) And (3) calculating the result:
the calculation formula of the content of chloride ions in the chromium-containing sludge is as follows:
in the formula:
ω(Cl-) -chloride ion content,%, in the sample;
c, concentration of silver nitrate standard titration solution, mol/L;
V1-volume of silver nitrate standard titration solution consumed in titrating the sample, mL;
V0-volume of silver nitrate standard titration solution consumed in titrating the blank, mL;
lc-loss on ignition coefficient of the sample;
m-weighing the mass of the sample, g;
35.45-molar mass of Cl atoms, g/mol.
The calculation formula of the loss on ignition coefficient Lc is as follows:
in the formula:
m1weighing the mass g of the sample before firing treatment;
m2-drying the treated porcelain boat mass, g;
m3the combined amount of the porcelain boat and the sample after firing treatment, g;
lc-loss on ignition coefficient of the sample.
(8) Detection limit and lower measurement limit of the method: the blank solution was measured 10 times in succession, and 3 times the standard deviation of the 10 measurements was taken as the detection limit, and 5 times the detection limit was taken as the lower measurement limit of the method, as shown in Table 2.
TABLE 2 detection limits and lower measurement limits of chlorine
| Element(s) | Standard deviation/% | Detection limit/%) | Determination lower limit/%) |
| Cl | 0.0007 | 0.0022 | 0.011 |
Example 2
The method comprises the following specific steps:
(1) drying and grinding: taking a chromium-containing sludge sample No. 2 back on site, placing the chromium-containing sludge sample in a drying box, drying the chromium-containing sludge sample for 2 hours at 105 ℃, grinding the dried chromium-containing sludge sample for 80 seconds in a vibration mill, and screening the chromium-containing sludge sample with a 120-mesh metal screen;
(2) high-temperature firing: weighing 2.0000g (accurate to 0.0001g) of the sample obtained in the step (1), putting the sample into a porcelain boat which is dried in advance to constant weight, putting the porcelain boat into a high-temperature furnace, burning the porcelain boat for 1.5h at 850 ℃, and calculating a loss on ignition coefficient Lc;
(3) dissolving and reducing: weighing 0.3000g of the sample obtained in the step (2), wetting the sample with 2mL of water, adding 20mL of 50% dilute nitric acid to dissolve the sample, and slowly dropwise adding 1.5mL of hydrogen peroxide solution;
(4) and (3) precipitation and filtration: adding 50mL of water into the solution, boiling, slowly adding 50mL of 50% diluted ammonia water until the solution generates a slight ammonia smell, then adding 5mL of water, standing for 10min, filtering by using slow quantitative filter paper, washing the container with water and precipitating for not less than 3 times, and recovering the filtrate and the washing liquid into a 150mL beaker;
(5) acidifying: adding 10mL of 50% dilute nitric acid into the filtrate to obtain a solution to be detected;
(6) detecting by an instrument: titrating the solution to be tested in the step (5) by using 1.0mol/L silver nitrate standard titration solution on a potentiometric titrator, and recording the titration volume V1Recording the titration volume V along with the blank test0See table 3;
TABLE 32 titration volumes of solutions to be tested and blank solutions of chromium-containing sludge samples
The formula for calculating the chloride ion content and the loss on ignition coefficient Lc is the same as in example 1.
Example 3
The method comprises the following specific steps:
(1) drying and grinding: taking a chromium-containing sludge sample No. 3 back on site, placing the chromium-containing sludge sample in a drying box, drying the chromium-containing sludge sample for 2 hours at 110 ℃, grinding the dried chromium-containing sludge sample for 80 seconds by a vibration mill, and sieving the chromium-containing sludge sample with a 120-mesh metal mesh screen;
(2) high-temperature firing: weighing 1.0000g (accurate to 0.0001g) of the sample obtained in the step (1), putting the sample into a porcelain boat which is dried in advance to constant weight, putting the porcelain boat into a high-temperature furnace, burning the porcelain boat for 2 hours at 850 ℃, and calculating a loss on ignition coefficient Lc;
(3) dissolving and reducing: weighing 0.2000g of the sample obtained in the step (2), wetting the sample with 1mL of water, adding 10mL of 50% dilute nitric acid for dissolving, and slowly dropwise adding 1.5mL of hydrogen peroxide solution;
(4) and (3) precipitation and filtration: adding 50mL of water into the solution, boiling, slowly adding 40mL of 50% diluted ammonia water until the solution generates a slight ammonia smell, then adding 3mL of water, standing for 8min, filtering by using slow quantitative filter paper, washing the container with water and precipitating for not less than 3 times, and recovering the filtrate and the washing liquid into a 150mL beaker;
(5) acidifying: adding 10mL of 50% dilute nitric acid into the filtrate to obtain a solution to be detected;
(6) detecting by an instrument: titrating the solution to be tested in the step (5) by using 0.5mol/L silver nitrate standard titration solution on a potentiometric titrator, and recording the titration volume V1Recording the titration volume V along with the blank test0See table 4;
TABLE 43 titration volumes of solutions to be tested and blank solutions of chromium-containing sludge samples
The formula for calculating the chloride ion content and the loss on ignition coefficient Lc is the same as in example 1.
The content of chlorine element in the chromium-containing sludge samples of examples 1 to 3 was measured, 10 times for each sample was conducted in parallel, precision tests were conducted, and the average value and the Relative Standard Deviation (RSD) of the test results were calculated, and the results are shown in table 5. The data in Table 5 show that the Relative Standard Deviation (RSD) of chlorine is between 0.94 and 2.10 percent, and the result is satisfactory.
Table 5 precision measurement results (n ═ 10)
The accuracy of the method of the invention is verified by using a labeling recovery test, and 3 levels of labeling tests are respectively carried out, and the results are shown in table 6. The data in Table 6 show that the recovery rate of the chlorine added standard is between 96.0 and 103.0 percent, and the result is satisfactory.
TABLE 6 results of recovery measurements with addition of standard
As can be seen from tables 5 to 6, the method of the present invention has good recovery rate and accuracy, and is favorable for popularization and application.
The above-mentioned examples only express the specific embodiments of the present invention, but should not be construed as limiting the scope of the present invention. Any modifications of the present invention which would occur to those skilled in the art and which are within the spirit of the invention are considered to be within the scope of the present invention.
Claims (10)
1. A method for measuring the content of chloride ions in cold-rolled chromium-containing sludge is characterized by comprising the following steps:
step 1: drying and grinding: taking back the sample on site, drying in a drying box, grinding by a vibration mill, and sieving;
step 2: high-temperature firing: weighing the dried and ground sample, placing the sample in a porcelain boat which is dried in advance to constant weight, placing the porcelain boat in a high-temperature furnace for burning, and calculating a loss on ignition coefficient Lc;
and step 3: dissolving and reducing: weighing a sample, wetting the sample with 1-2 mL of water, adding 10-20 mL of dilute nitric acid for dissolving, and slowly dropwise adding 1-2 mL of hydrogen peroxide for reducing hexavalent chromium;
and 4, step 4: and (3) precipitation and filtration: adding water into the solution, boiling, slowly adding 30-50 mL of dilute ammonia water until the solution generates a slight ammonia smell, supplementing 3-5 mL of dilute ammonia water, standing for a period of time, filtering and precipitating, washing a container and precipitating for several times, and recovering filtrate and washing liquor to a beaker;
and 5: acidifying: adding 10mL of dilute nitric acid into the filtrate for acidification to obtain a solution to be detected;
step 6: detecting by an instrument: titrating the solution to be tested in the step 5 by using a silver nitrate standard titration solution on a potentiometric titrator, and recording the titration volume V1Recording the titration volume V along with the blank test0；
And 7: and (3) calculating the result: the calculation formula of the content of chloride ions in the chromium-containing sludge is as follows:
in the formula:
ω(Cl-) -chloride ion content,%, in the sample;
c, concentration of silver nitrate standard titration solution, mol/L;
V1-volume of silver nitrate standard titration solution consumed in titrating the sample, mL;
V0-volume of silver nitrate standard titration solution consumed in titrating the blank, mL;
lc-loss on ignition coefficient of the sample;
m-weighing the mass of the sample, g;
35.45-molar mass of Cl atoms, g/mol.
2. The method for determining the chloride ion content in the chromium-containing sludge in the cold rolling process according to claim 1, which is characterized in that: in the step 1, the drying and grinding process comprises: the drying temperature of the drying oven is 105-110 ℃, and the drying time is 2 h; the vibration grinding time is 60-80 s, and the granularity of the metal mesh screen is 120 meshes.
3. The method for determining the chloride ion content in the chromium-containing sludge in the cold rolling process according to claim 1, which is characterized in that: in the step 2, the high-temperature burning process includes: weighing 1.0000-2.0000 g of sample, wherein the ignition temperature of the high-temperature furnace is 750-850 ℃, and the ignition time is 1.5-2 h.
4. The method for determining the chloride ion content in the chromium-containing sludge in the cold rolling process according to claim 1, which is characterized in that: in the step 2, the calculation formula of the loss on ignition coefficient Lc is as follows:
in the formula:
m1weighing the mass g of the sample before firing treatment;
m2-the mass of the porcelain boat after drying, g；
m3The combined amount of the porcelain boat and the sample after firing treatment, g;
lc-loss on ignition coefficient of the sample.
5. The method for determining the chloride ion content in the chromium-containing sludge in the cold rolling process according to claim 1, which is characterized in that: in the step 3, the weight of the weighed sample is 0.2000-0.3000 g.
6. The method for determining the chloride ion content in the chromium-containing sludge in the cold rolling process according to claim 1, which is characterized in that: in the step 3, the concentration of the nitric acid before the dilute nitric acid is diluted is 1.42g/cm3The concentration of the hydrogen peroxide is 1.13g/cm3。
7. The method for determining the chloride ion content in the chromium-containing sludge in the cold rolling process according to claim 1, which is characterized in that: in the step 4, the precipitation and filtration process comprises: standing for 5-10 min, filtering with slow quantitative filter paper, washing the container and precipitating for at least 3 times, and recovering filtrate and washing liquid in a beaker with a volume of 150 mL.
8. The method for determining the chloride ion content in the cold-rolled chromium-containing sludge according to claim 1, characterized in that: in the step 4, the concentration of the ammonia water before the diluted ammonia water is 0.91g/cm3(ii) a The volume fraction of the dilute ammonia water is 50%.
9. The method for determining the chloride ion content in the chromium-containing sludge in the cold rolling process according to claim 1, which is characterized in that: in the steps 3 and 5, the volume fraction of the dilute nitric acid is 50%.
10. The method for determining the chloride ion content in the chromium-containing sludge in the cold rolling process according to claim 1, which is characterized in that: in the step 6, the concentration of the silver nitrate standard titration solution is 0.50-1.00 mol/L.
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| CN114965326A (en) * | 2022-07-28 | 2022-08-30 | 山东飞源气体有限公司 | Method for measuring nickel content in waste residue generated by nitrogen trifluoride electrolysis |
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