Seek the detection method for aluminum trichloride

VI. Determination of test methods 6.1 Determination of aluminum chloride content As can be seen from Appendix 2, for the determination of aluminum chloride content, the American military standard MIL-A-63471—1987 \"Anhydrous aluminum chloride\" employs the acid-base titration method. That is, the test solution is made alkaline using sodium hydroxide solution and an excess of saturated barium hydroxide solution; potassium fluoride solution is added, and it is titrated with a standard hydrochloric acid solution. The original national standard GB/T 3959—1994 \"Industrial anhydrous aluminum chloride\" used the mercury method. The test solution was adjusted to a weakly acidic pH using a (1+1) nitric acid solution. Diphenylazocarbazide was used as an indicator, and a standard mercury nitrate titrant was employed to titrate the chloride ions, with a blank test also conducted. Both methods have their drawbacks: the American military standard uses barium hydroxide, which generates barium chloride during the reaction; the addition of potassium fluoride together with aluminum results in the formation of insoluble aluminum fluoride, leaving fluoride ions behind, and the solution resulting from the titration contaminates the environment. The method of the original national standard uses mercury nitrate as a titrant, and the solution after titration also needs to be treated; however, treating mercury-containing solutions is quite difficult. Therefore, potentiometric titration is adopted in this revision; this method is also a common approach for measuring chloride ions. 6.2 Determination of iron content: For the determination of iron content, both the original standard GB/T 3959—1994 \"Industrial anhydrous aluminum chloride\" and the U.S. military standard MIL-A-63471—1987 \"Anhydrous aluminum chloride\" employ the 1,10-phenanthroline spectrophotometric method. This method is a standard general method, and this standard can continue to be used. Only *the general method has been revised; this method requires further verification. 6.3 Determination of water-insoluble matter content The determination of water-insoluble matter content can be carried out using the gravimetric method with a Guerbet crucible or the gravimetric method with a glass sand crucible ； The original standard GB/T 3959—94 \"Industrial anhydrous aluminum chloride\" used the gravimetric method with G4 crucibles. Both methods are applicable to this product; however, the * crucible method is more complicated to operate, and the quality of the acid-washed asbestos often affects the speed and accuracy of the tests. Therefore, this standard continues to use the method specified in the original national standard. 6.4 Determination of heavy metal content (expressed as Pb): For the determination of heavy metal content (expressed as Pb), China’s standard GB/T 3959—94 \"Industrial anhydrous aluminum chloride\" employs a limit colorimetric method. First, the test solution is adjusted to a weakly acidic pH, after which saturated hydrogen sulfide solution is introduced to cause the heavy metal ions to form precipitates with hydrogen sulfide; these precipitates are then compared in color with a standard colorimetric solution. American military standard MIL-A-63471—1987 \"Anhydrous aluminum chloride\" does not include this specification nor the corresponding testing methods. Currently, many standards have replaced heavy metals with lead as the indicator, using atomic absorption spectrophotometry. The draft for comments retains the method from the original standards for now; it will be revised after extensive feedback from manufacturers and comparative tests are conducted. 6.5 Determination of free aluminum content: Both the U.S. military standard MIL-A-63471—1987 \"Anhydrous aluminum chloride\" and China’s standard GB/T 3959—94 \"Industrial anhydrous aluminum chloride\" specify the use of a potassium dichromate standard titrant in a sulfuric-phosphoric acid medium, in the presence of ferric trichloride, with sodium diphenylamine sulfonate as an indicator for the titration. VII. Inspection Rules Classification of inspection items: type inspection and factory inspection ； All items are type inspection items; among them, aluminum chloride, iron, water-insoluble substances, and heavy metals are exit inspection items that must be tested batch by batch. Each batch of products shall not exceed 50 tons.

Appendix 2 Comparison of Domestic and International Standard Test Methods Index Item Standard Code GB/T 3959—94 Industrial anhydrous aluminum chloride MIL-A-63471—1987 “Anhydrous aluminum chloride” Content of aluminum chloride (AlCl3): Titration is carried out using mercuric nitrate, with diphenylazocarbazide as an indicator. The pH is adjusted using sodium hydroxide and saturated barium hydroxide, followed by titration with hydrochloric acid. Iron content (as FeCl3): 1,10-phenanthroline spectrophotometry. Water-insoluble matter content: gravimetric method. Heavy metal content (as Pb): limit colorimetric method. Free aluminum content: titrated with potassium dichromate, using sodium diphenylamine sulfonate as an indicator. Moisture content: gravimetric method