Method for detecting chromium content in organic chromium compound
Through the titration method after freezing treatment and catalytic oxidation, the problem of difficulty in detecting the chromium content in non-solid organic chromium compounds in traditional titration methods is solved, and the accurate chromium content detection of different forms of organochromium compounds is achieved, which is highly efficient and universal Detection method.
Patent Information
- Application Number
- CN202411389284.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-08
- Publication Date
- 2024-12-13
AI Technical Summary
Traditional titration methods are difficult to accurately detect the chromium content in non-solid organochromium compounds.
After the organic chromium compound is frozen, the mixed acid of ammonium persulfate and thiophosphate are used for boiling and dissolving, and the trivalent chromium is oxidized to hexavalent chromium under the catalysis of silver nitrate. Then the indicator is added for titration reaction until the color changes to bright green. to determine the chromium content.
It realizes accurate and rapid detection of organic chromium compounds regardless of solid, liquid or gaseous state, is universal, has small detection errors, and is suitable for a wide range of fields.
Smart Images
Figure CN119125437A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of chromium content detection, and in particular to a method for detecting chromium content in an organic chromium compound. Background Art
[0002] The traditional titration method for detecting chromium content uses ammonium persulfate and sulfuric acid to detect the chromium content in organic chromium compounds. During the detection process, solid organic chromium compounds easily react with ammonium persulfate and sulfuric acid in a conical flask.
[0003] Aqueous solution can cover solid organic chromium compounds, with a large contact area and a relatively stable reaction rate. However, when it comes to non-solid organic chromium compounds, the traditional titration method is difficult to detect the chromium content. Therefore, we proposed a method for detecting chromium content in organic chromium compounds to solve the above problem. Summary of the invention
[0004] The purpose of the present invention is to overcome the deficiencies in the above-mentioned background technology and to propose a method for detecting the chromium content in an organic chromium compound.
[0005] In order to achieve the above object, the present invention adopts the following technical solutions:
[0006] A method for detecting the chromium content in an organic chromium compound, the method comprising:
[0007] S1: freezing the organochromium compound.
[0008] S2: Take the frozen organic chromium compound and add water, ammonium persulfate and sulfuric acid.
[0009] S3: Boil until the organic chromium compound dissolves, and continue boiling until white smoke appears.
[0010] S4: After cooling, add ammonium persulfate to oxidize trivalent chromium to hexavalent chromium under the catalysis of silver nitrate. Continue boiling. After cooling, add indicator and titrate with standard ammonium ferrous sulfate solution until the color of the aqueous solution changes from blue-purple to bright green.
[0011] Preferably, the selected gaseous organochromium compound needs to be condensed before being frozen.
[0012] Preferably, the ratio of the weight of the selected organic chromium compound sample to the volume of the sulfur-phosphorus mixed acid solution is 1:40, that is, 0.5 g of the organic chromium compound sample is added to 20 mL of the sulfur-phosphorus mixed acid solution.
[0013] Preferably, in step S2, the weight of the selected ammonium persulfate added is 2 g.
[0014] Preferably, in step S3, if the selected organic chromium compound is not completely dissolved, 50 mL of water is added after cooling, and then 2 g of ammonium persulfate is added and boiled until the sample is completely dissolved, and the boiling is continued until white smoke is emitted.
[0015] Preferably, in step S4, the indicator selected is N-phenylanthranilic acid.
[0016] Preferably, the sulfur-phosphorus mixed acid solution is a solution formed by mixing three volumes of sulfuric acid with two volumes of phosphoric acid.
[0017] The beneficial effects of the present invention are:
[0018] The method for detecting the chromium content in an organic chromium compound proposed by the present invention is a method for detecting the chromium content in an organic chromium compound with a simple process and high efficiency. The detection method first adopts a method of freezing the organic chromium compound so that the organic chromium compound, whether liquid or gaseous, can better contact and react with the reaction solution, so that the detection method can accurately and quickly detect the chromium content in the organic chromium compound, has universality, and can be widely used in more fields. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 The present invention provides a flow chart of a method for detecting chromium content in an organic chromium compound. DETAILED DESCRIPTION
[0020] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.
[0021] Reference Figure 1 , a method for detecting the chromium content in an organic chromium compound, the method for determining the chromium content in an organic chromium compound comprises:
[0022] S1: Freeze the organic chromium compound. S2: Take the frozen organic chromium compound, add water, ammonium persulfate and sulfuric acid. S3: Boil until the organic chromium compound dissolves, and continue to boil until white smoke appears. S4: After cooling, add ammonium persulfate, and oxidize trivalent chromium to hexavalent chromium under the catalysis of silver nitrate, continue to boil, add indicator after cooling, and titrate with ammonium ferrous sulfate standard solution until the color of the aqueous solution suddenly changes from blue-purple to bright green.
[0023] Example 1
[0024] 1. Take out the solid organic chromium compound and freeze it.
[0025] 2. Weigh 0.5 g of frozen solid organic chromium compound into a 250 ml conical flask, add 50 ml of pure water, shake well, add 2 g of ammonium persulfate, and after the ammonium persulfate is dissolved, add 15 ml of sulfuric acid and phosphoric acid mixed solution.
[0026] 3. Boil until the organic chromium compound is dissolved, and continue to boil until white smoke is emitted. If the solid organic chromium compound is not completely dissolved, add 50 mL of water after cooling, and then add 2 g of ammonium persulfate and boil until the sample is completely dissolved, and continue to boil until white smoke is emitted.
[0027] 4. After cooling, add 250 mL of water and 5 g of ammonium persulfate, add 5 mL of silver nitrate solution (17 g / L) to oxidize trivalent chromium to hexavalent chromium, boil for 5 minutes, cool, add ammonium ferrous sulfate until it turns green, add 5 drops of N-phenylanthranilic acid, and titrate with 0.1008 mol / L (NH4)2Fe(SO4)2 standard titration solution. The color changes from blue-purple to bright green, which is the titration end point.
[0028] The solid organic chromium compound with known content is used as the standard sample, and the chromium content in the chromium picolinate is measured by the above-mentioned determination method. The chemical formula of the obtained result and the chromium picolinate is Cr(CHNO)3, and the mass fraction of chromium calculated in theory is about 12.43%. Compared with the known content, the accuracy of the result obtained by the method of the present invention is judged. Three groups of tests are carried out, and the experimental results show that the chromium contents of the chromium picolinate measured by the three groups of tests are 12.22%, 12.17% and 12.26% respectively, and the average chromium content is 12.22%, the error is 0.21%, and the relative error value RE=1.69%.
[0029] Example 2
[0030] 1. Take out the liquid organic chromium compound and freeze it.
[0031] 2. Weigh 0.5g of frozen liquid organic chromium compound into a 250ml conical flask, add 50mL of pure water, shake well, add 2g of ammonium persulfate, and after the ammonium persulfate is dissolved, add 15mL of sulfuric acid and phosphoric acid mixed solution. Keep it sealed during the whole process.
[0032] 3. Boil until the liquid organic chromium compound is dissolved, and continue to boil until white smoke is emitted. If the liquid organic chromium compound is not completely dissolved, add 50 mL of water after cooling, and then add 2 g of ammonium persulfate and boil until the liquid organic chromium compound is completely dissolved, and continue to boil until white smoke is emitted.
[0033] 4. After cooling, add 250 mL of water and 5 g of ammonium persulfate, add 5 mL of silver nitrate solution (17 g / L) to oxidize trivalent chromium to hexavalent chromium, boil for 5 minutes, cool, add ammonium ferrous sulfate until it turns green, add 5 drops of N-phenylanthranilic acid, and titrate with 0.1008 mol / L (NH4)2Fe(SO4)2 standard titration solution. The color changes from blue-purple to bright green, which is the titration end point.
[0034] The chromium content in the chromium acetylacetonate is determined by the above-mentioned determination method using a liquid organic chromium compound with a known content, chromium acetylacetonate, as a standard sample. The chemical formula of chromium acetylacetonate is C15H24CrO6, and the mass fraction of chromium calculated theoretically is about 14.90%. The known content is compared to determine the accuracy of the results obtained by the method of the present invention. Three groups of tests are conducted. The experimental results show that the chromium contents of the chromium acetylacetonate measured in the three groups of tests are 14.52%, 14.77% and 14.60% respectively, with an average chromium content of 14.63%, an error of 0.27%, and a relative error value RE=1.79%.
[0035] Example 3
[0036] 1. The gaseous organic chromium compounds are condensed before being measured, and the condensed gaseous organic chromium compounds are taken out and frozen.
[0037] 2. Weigh 0.5g of frozen gaseous organic chromium compound into a 250ml conical flask, add 50mL of pure water, shake well, add 2g of ammonium persulfate, and after the ammonium persulfate is dissolved, add 15mL of sulfur-phosphorus mixed acid solution. Keep it sealed during the whole process.
[0038] 3. Boil until the frozen gaseous organic chromium compound is dissolved, and continue to boil until white smoke is emitted. If the frozen gaseous organic chromium compound is not completely dissolved, add 50 mL of water after cooling, and then add 2 g of ammonium persulfate and boil until the frozen gaseous organic chromium compound is completely dissolved, and continue to boil until white smoke is emitted.
[0039] 4. After cooling, add 250 mL of water and 5 g of ammonium persulfate, add 5 mL of silver nitrate solution (17 g / L) to oxidize trivalent chromium to hexavalent chromium, boil for 5 minutes, cool, add ammonium ferrous sulfate until it turns green, add 5 drops of N-phenylanthranilic acid, and titrate with 0.1008 mol / L (NH4)2Fe(SO4)2 standard titration solution. The color changes from blue-purple to bright green, which is the titration end point.
[0040] A gaseous organic chromium compound with a known content is used for analysis. Hexacarbonyl chromium can be sublimated into gas at room temperature. Hexacarbonyl chromium is used as a standard sample. The chromium content in hexacarbonyl chromium is determined by the above-mentioned determination method. The chemical formula of hexacarbonyl chromium is Cr(CO)6. The mass fraction of chromium calculated in theory is about 23.64%. Compared with the known content, the accuracy of the results obtained by the method of the present invention is judged. Three groups of experiments are carried out. The experimental results show that the chromium contents of chromyl chloride measured in the three groups of experiments are 23.25%, 23.14% and 23.27% respectively, the average chromium content is 23.22%, the error is 0.42%, and the relative error value RE=1.75%.
[0041] Based on the above data, the relative error values of the chromium content in Examples 1, 2 and 3 are 1.69%, 1.79% and 1.75% respectively, the relative error value floating range is between 0.007% and 0.053%, and the average relative error value is 1.74%. When the chromium content detection method is used to measure different organic chromium compounds in different forms, the detection error values are not much different, and the average specific error value is 1.74%, that is, the quality of the measured chromium content is improved by 1.74%, that is, the chromium content in the chromium compound is detected.
[0042] It is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited to it. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.
Claims
1. A method for detecting chromium content in an organic chromium compound, characterized in that: The detection method for determining the chromium content in the organic chromium compound comprises: S1: freezing the organochromium compound. S2: Take the frozen organic chromium compound and add water, ammonium persulfate and sulfuric acid. S3: Boil until the organic chromium compound dissolves, and continue boiling until white smoke appears. S4: After cooling, add ammonium persulfate to oxidize trivalent chromium to hexavalent chromium under the catalysis of silver nitrate. Continue boiling. After cooling, add indicator and titrate with standard ammonium ferrous sulfate solution until the color of the aqueous solution changes from blue-purple to bright green.
2. The method for detecting chromium content in an organic chromium compound according to claim 1, characterized in that: The selected gaseous organochromium compound must be condensed before freezing.
3. The method for detecting chromium content in an organic chromium compound according to claim 1, characterized in that: The ratio of the weight of the selected organic chromium compound sample to the volume of the sulfur-phosphorus mixed acid solution is 1:40, that is, 0.5 g of the organic chromium compound sample is added to 20 mL of the sulfur-phosphorus mixed acid solution.
4. The method for detecting chromium content in an organic chromium compound according to claim 1, characterized in that: In step S2, the weight of the selected ammonium persulfate added is 2 g.
5. The method for detecting chromium content in an organic chromium compound according to claim 1, characterized in that: In step S3, the selected organic chromium compound is not completely dissolved. After cooling, 50 mL of water is added, and then 2 g of ammonium persulfate is added and boiled until the sample is completely dissolved, and the boiling is continued until white smoke is emitted.
6. The method for detecting chromium content in an organic chromium compound according to claim 1, characterized in that: In step S4, the indicator selected is N-phenylanthranilic acid.
7. The method for detecting chromium content in an organic chromium compound according to claim 1, characterized in that: The sulfur-phosphorus mixed acid solution used is a solution formed by mixing three parts by volume of sulfuric acid with two parts by volume of phosphoric acid.