Method for preparing primary standard reagent potassium bichromate

Abstract

The invention relates to a method for preparing a standard reagent of potassium dichromate, comprising the following preparation steps: (1) dissolving potassium dichromate in deionized water and forming a potassium dichromate solution; (2) adding barium nitrate and eliminating sulfate radical, filtering after the solution keeps still, and the obtained filtrate crystallizing naturally and forming crystal; (3) adding the deionized water to the crystal and dissolving; (4) adding sodium polyacrylate and discharging the sediment; (5) pouring the filtrate into a crystal groove for crystallization, dewatering the crystal by using a dewaterer for crystal, putting the crystal after dewartering into a dryness box and drying at a constant temperature, and obtaining the finished product of the standard reagent of potassium dichromate. In the invention, dilute sulphuric acid is used for transferring the minute amounts of potassium chromate in the raw material into the potassium dichromate entirely, and the content is improved; the adopted sodium polyacrylate can facilitate the metallic ions to agglomerate and sink rapidly, thus the water insoluble can reach the best effect; and a multi-temperature crystallization method is adopted for confirming the temperature grads of crystallization, and the best effects can be reached that all the grain diameters are 0.5 mm, grains are even, and the content is parallel.

Description

Technical field [0001] The invention belongs to the field of chemical reagents, in particular to a method for preparing a reference reagent potassium dichromate. Background technique [0002] At present, potassium dichromate used as the reference reagent is prepared in this way. Dissolve 100g of industrial potassium dichromate in 1Kg of hot water, filter, and evaporate the filtrate to 1 / 7 of the original volume. Cool and stir quickly. The disadvantages are The potassium chromate in the industrial potassium dichromate raw material is not completely converted into potassium dichromate. The powdery crystallized by strong cooling and rapid stirring is not parallel in content, which affects the accuracy of detection and is not acceptable to customers. The preparation method is: dissolve industrial potassium dichromate in deionized water, add dilute sulfuric acid to completely convert the potassium chromate in the raw material into potassium dichromate, then add barium salt, remove sul...

AI Technical Summary

Problems solved by technology

[0002] Potassium dichromate as benchmark reagent is prepared like this at present, and 100g industrial potassium dichromate is dissolved in 1Kg hot water, filters, and when evaporating filtrate to 1 / 7 of original volume, cooling and rapid stirring, the deficiency of existence is Potassium chromate in industrial potassium dichromate raw materials is not completely converted into potassium dichromate, and the product crystallized by strong cold and rapid stirring is powdery, and the content is not parallel, which affects the accuracy of detection and is not accepted by customers. However, our The preparation method is: dissolve industrial potassium dichromate in deionized water, add dilute sulfuric acid, completely convert the potassium chromate in the raw material into potassium dichromate, then add barium salt, remove sulfate, filter and then add sodium polyacrylate , so that the metal ions quickly condense and sink, and then filter, and use the multi-temperature crystallization method to form uniform granular high-content and parallel potassium dichromate

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