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Method for rapid determination of liquid phase sulfate content in the production process of potassium dihydrogen phosphate

A production process technology of potassium dihydrogen phosphate, which is applied in the field of analytical chemistry, can solve the problems of slow discoloration at the end point of titration, cumbersome steps, and long time consumption, and achieve the effect of sensitive discoloration of the system and improvement of detection accuracy

Active Publication Date: 2019-05-28
HUBEI SANNING CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The gravimetric method is highly accurate and mature, but the steps are cumbersome and time-consuming, and it is not suitable for rapid analysis
The titration method is generally titrated with standard barium chloride solution or EDTA under the condition of pH greater than 5, but at this pH value, barium ions can combine with phosphate ions to form precipitates, resulting in large errors, and there are also titration The problem of slow color change at the end point
Spectrophotometry has the advantages of fast and accurate, but when applied to this system, the sample needs to be diluted at least 50 times or even higher, and once the production is abnormal, it is easy to exceed the standard curve measurement range
Sodium rhodamine colorimetric method is a widely used method. It is under the condition of pH 5.5-7, using sodium rhodamine as an indicator, and determining the concentration range of sulfate radicals through color development, with high accuracy. It has the advantages of high speed and high speed, but when it is applied to this system, there are also situations where phosphate radicals and barium ions are combined, and in a strong acidic environment, it is easy to form a pink transition color, resulting in large errors
[0003] This shows that at present there is not a kind of method that is fully applicable to the quick measurement liquid phase sulfate radical content in this potassium dihydrogen phosphate production process

Method used

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  • Method for rapid determination of liquid phase sulfate content in the production process of potassium dihydrogen phosphate
  • Method for rapid determination of liquid phase sulfate content in the production process of potassium dihydrogen phosphate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Take 3mL, 3.5mL, 4mL, 4.5mL barium chloride standard solution into four 25mL colorimetric tubes respectively with a burette, then add 2mL acetic acid solution, 4mL stabilizer (50% ethanol + 30% chloroform + 20 % glyceryl stearate), 5-6 drops of sodium roseate indicator solution. Filter the sample, pipette 4mL filtrate into four colorimetric tubes, and shake the colorimetric tubes for about 30 seconds after the tubes are tightly plugged. The colors of the four colorimetric tubes are white, white, white, and red in sequence. Formula (1) calculates that the sulfate content in the sample is 0.85%, and the sulfate content in the sample is determined by gravimetric method to be 0.81%, and the error between the two is 0.04%. After the colorimetry, the pH value of the four colorimetric tubes was measured with a precision pH meter to be 2.5-2.6.

Embodiment 2

[0028] Take 3mL, 3.5mL, 4mL, 4.5mL barium chloride standard solution into four 25mL colorimetric tubes respectively with a burette, then add 3mL acetic acid solution, 4mL stabilizer (40% ethanol + 40% chloroform + 20 % methyl isobutyl ketone), 5-6 drops of sodium roseate indicator solution. Filter the sample, draw 2mL of the filtrate with a pipette and add them to the four colorimetric tubes. After tightening the stoppers, shake the colorimetric tubes for about 30 seconds. The colors of the four colorimetric tubes are all white. Take another colorimetric tube and add 5mL barium chloride standard solution, the other operations are the same as above, the color of the colorimetric tube is red. Calculate according to (1) formula and obtain the sulfate radical content in the sample to be 1.90%, measure the sulfate radical content in the sample with gravimetry simultaneously and be 1.84%, both error is 0.06%. After the colorimetry was finished, the pH value of the colorimetric tube...

Embodiment 3

[0030] Take 2mL, 2.5mL, 3mL, 3.5mL of barium chloride standard solution into four 25mL colorimetric tubes respectively with a burette, then add 3mL of acetic acid solution and 4mL of stabilizer (40% ethanol + 40% acetone + 20% three ethanolamine), 5-6 drops of sodium rhodamine indicator solution. Filter the sample, draw 2mL filtrate into four colorimetric tubes with a pipette, and shake the colorimetric tubes for about 30 seconds after the tubes are tightly plugged. The colors of the four colorimetric tubes are white, white, red, and red respectively. (1) formula calculates and obtains that sulfate radical content is 1.10% in the sample, measures the sulfate radical content in the sample with gravimetric method simultaneously and is 1.07%, both error is 0.03%. After the colorimetry, the pH value of the colorimetric tubes in this group was measured by a precision pH meter at 2.0-2.1.

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Abstract

The invention discloses a method for rapid determination of sulfate radical content in a liquid phase in the process of production of potassium dihydrogen phosphate, and belongs to the field of analytical chemistry. The method comprises the following steps: taking barium chloride standard solutions with different volume gradients into colorimetric tubes, successively adding an acid, a stabilizer, an indicator and a to-be-tested sample, rapidly shaking the colorimetric tubes for 30s, observing the color change of the colorimetric tubes; and if one of adjacent colorimetric tubes shows red, and the other one of the adjacent colorimetric tubes shows white, determining that the to-be-tested sulfate radical concentration is between the concentration marked by the colorimetric tube showing red and the concentration marked by the colorimetric tube showing white. The method is an improvement of a sodium rhodizmate colorimetric method, by adding of the stabilizer, the method can also be applied under the condition of acidity, transition color can be eliminated, and detection precision is improved.

Description

technical field [0001] The invention belongs to the field of analytical chemistry, and in particular relates to a method for quickly measuring the sulfate radical content in liquid phase during the process of producing potassium dihydrogen phosphate through metathesis reaction of calcium hydrogen phosphate and potassium hydrogen sulfate. Background technique [0002] Hubei Sanning Chemical Co., Ltd. has independently developed a new process for preparing potassium dihydrogen phosphate by the reaction of calcium hydrogen phosphate and potassium hydrogen sulfate (patent number CN102424374A). This process needs to control the liquid-phase sulfate content in the reaction slurry to 1.5 % (mass fraction, the same below), this just needs to provide a kind of method for fast determination sulfate radical content, to realize the real-time monitoring of liquid phase sulfate radical content in production. At present, the methods for determining sulfate content mainly include gravimetri...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N21/78
CPCG01N21/78
Inventor 周炜张小元廖秋实肖林波谭贤妮熊其莲
Owner HUBEI SANNING CHEM
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