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A calcium hydroxide and benchmark technology, applied in the direction of calcium/strontium/barium oxide/hydroxide, etc., can solve the problems of inaccurate pH value of pH benchmark reagents, difficult to meet the use requirements, poor stability, etc., to shorten the production time , reduce precipitation and adsorption, and increase yield
Inactive Publication Date: 2016-05-11
TIANJIN GUANGFU TECH DEV
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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
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Embodiment 1
[0025] A method for rapidly preparing pH benchmark calcium hydroxide, the steps are as follows:
[0026] (1) Dissolve 100Kg of industrial calcium nitrate in 100Kg of distilled water and heat to dissolve;
[0027] (2) Add 105Kg calcium hydroxide solution to the solution, the reaction temperature is 80°C, the reaction time is 1 hour, and the solution is kept warm for 1 hour.
[0028] (3) Filtrate with an activated carbon funnel, heat the solution to 80°C, add 75Kg of sodium hydroxide (40%) solution, and adjust the pH to 12.5; after 1 hour, the dissolved matter is precipitated, and the heated dissolved matter is dried and washed with water three times;
[0029] (4) Spin dry again, and then dry again. The drying temperature is controlled at 100°C for about 5 hours to obtain the qualified pH benchmark reagent calcium hydroxide.
Embodiment 2
[0031] A method for rapidly preparing pH benchmark calcium hydroxide, the steps are as follows:
[0032] (1) 200Kg industrial calcium nitrate, dissolved in 150Kg distilled water, heated to dissolve;
[0033] (2) Add 500g of solid sodium hydroxide to the solution, the reaction temperature is 90°C, dissolve for 2 hours, keep warm and settle for 1 hour;
[0034] (3) Filter with an activated carbon funnel, dissolve and clear, otherwise wake up and filter twice. Heat the cleared precipitate to 90°C, add 67Kg of sodium hydroxide, dissolve and react for 3 hours, keep the precipitation for 1 hour, dry the hot precipitate, and wash 3 times with 90°C water;
[0035] (4) Shake dry again, and dry at 90°C for about 5 hours to obtain calcium hydroxide, a qualified PH benchmark reagent.
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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...
Claims
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