ph reference reagent calcium hydrate preparation method

Abstract

The invention relates to a pH reference reagent calcium hydrate fast preparation method. The method comprises 1, dissolving industrial calcium nitrate in deionized water, carrying out heating for dissolution, adding a small amount of a calcium hydrate solution into the solution, carrying out a reaction process at a temperature of 70-80 DEG C for 0.5h, dissolving the reaction product for 1-2h and filtering the solution, 2, heating the solution to a temperature of 70-80 DEG C, adding sodium hydroxide into the solution according to a matrix ratio of 3: 1, accurately adjusting pH to 12.5-10.5 and carrying out a reaction process for 1-2h, 3, filtering the hot solution at a temperature of 70-80 DEG C and washing the precipitates through hot water 2-4 times, and 4, spin-drying the precipitates and drying the precipitates at a temperature of 80-100 DEG C for 8-10h to obtain the pH reference reagent calcium hydrate. The preparation method realizes Fe, Mg and SO4<2-> removal in one step, greatly shortens a process, saves time by 4-6h and improves production efficiency.

Description

technical field [0001] The invention belongs to the field of chemical reference reagents, in particular to a preparation method of calcium hydroxide, a pH reference reagent. technical background [0002] The reference reagent is a chemical substance specially used to directly prepare the standard solution, and it can also be used to calibrate the standard solution of other non-reference substances. The quality requirements of the reference reagent are very high, such as the composition is strictly consistent with its chemical formula, the purity is high, and the impurity content is low. Calcium hydroxide is the pH reference reagent, which is used to calibrate the working measurement of the acidity meter. It requires high PH accuracy and low content of impurities such as chloride ions, sulfate ions, magnesium and iron ions. At present, the synthesis of calcium hydroxide all adopts the direct synthesis method of calcium oxide and sodium hydroxide. The pH value of the pH refer...

AI Technical Summary

Problems solved by technology

At present, the synthesis of calcium hydroxide all adopts the direct synthesis method of calcium oxide and sodium hydroxide. The pH value of the pH reference reagent measured by this method is inaccurate and poor in stability, so it is difficult to meet the requirements for use, and because there is a large amount of Mg 2+ , Fe 3+ , Cl - exist, difficult to remove

[0003] According to the retrieval, it is found that the patent document CN102390854A discloses the use of SO4 2- , Mg 2+ and other processes, this process is carried out in three steps, the removal of SO4 2- , Mg 2+ , Fe 3+ , carried out separately, two precipitation separations were carried out, and repeated operations such as suction filtration and washing of the precipitate were generated. In addition, the raw material used was CaCl2, which brought in a large amount of Cl - , it is difficult to wash off, so the completion of the entire operation process takes 8-10 hours