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Process for determining metal content in terephthalic acid by plasma emission spectrum

A technology of terephthalic acid and emission spectroscopy, which is applied in the field of determination of metal content in crude terephthalic acid, can solve the problems of long operation time, environmental pollution, cumbersome steps, etc., and achieve reliable analysis results, high test accuracy, The effect of improving accuracy

Active Publication Date: 2006-04-26
SINOPEC YIZHENG CHEM FIBER
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

The above method is cumbersome to operate and the steps are cumbersome, which affects the accuracy of the measurement results
Especially when using the atomic absorption method to determine Al, Ca, Cr and Mo, it is necessary to use nitrous oxide-acetylene flame, which has potential safety hazards
Moreover, when more than six elements cannot be tested simultaneously on an atomic absorption spectrophotometer, the operation time is long, and it is not suitable for production process control
Moreover, when ashing samples, a large amount of smoke will be generated, which will pollute the environment and have adverse effects on human health and the environment.

Method used

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  • Process for determining metal content in terephthalic acid by plasma emission spectrum

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Embodiment 1

[0023] The selection of embodiment 1 ammonia concentration

[0024] See Table 1 for the solubility of 7g of terephthalic acid in 100ml of ammonia water of different concentrations.

[0025] See Table 2 for the test results of the maximum angle-dissolving amount of terephthalic acid in 100ml of the same concentration of ammonia.

[0026] 100ml ammonia concentration

[0027]

[0028] As can be seen from the above data, when the ammonia concentration is 4%, thick (or refined) terephthalic acid has the maximum solubility in the ammonia solution, 7g of soluble samples can be dissolved in this ammonia solution of 100ml, in order to obtain the maximum analysis strength, Therefore, 7 g of crude (or refined) terephthalic acid sample is dissolved in 100 ml of 4% ammonia solution.

Embodiment 2

[0029] The method of metal content in the terephthalic acid of embodiment 2

[0030] (1) Preparation of each metal standard solution

[0031] 1.1 Weigh 1.000g of high-purity metallic aluminum, dissolve it in 100mL of hydrochloric acid (50% by volume), transfer to a 1000mL volumetric flask, dilute with water to the mark and shake well. The concentration of this solution is 1mg / mL; take an appropriate amount of the above solution and dilute it 10 times to prepare a standard solution of 0.1mg / mL.

[0032] 1.2 Calcium standard solution (0.1mg / mL): Prepare according to 4.50.1 in GB / T602.

[0033] 1.3 Chromium standard solution (0.1mg / mL): Weigh 1.000g of high-purity metallic chromium, dissolve it in hydrochloric acid (50% by volume) after heating, transfer to a 1000mL volumetric flask after cooling, dilute with water to the mark and shake well. The concentration of this solution is 1.0mg / mL; take an appropriate amount of the above solution and dilute it 10 times to prepare a stan...

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Abstract

The invention discloses a PTA metal content method of plasma emission spectrum detection, which is characterized by the following: preparing the standard mixing solution with each metal content at 0.005mg / mL; washing the PTA from three to five times through electronic grade hydrochloric acid then through the pure water; drying the solution as the PTA background sample without metal; mixing the background sample and standard mixing solution and ammonia to generate six 100 ml sample solution of 7g PTA background sample with the metal element content at 0.00, 0.01, 0.05, 0.10, 0.15, 0.10 mg / L sequently; detecting the standard solution and sample solution through the plasma emission optical spectrometer zeroed by blank solution; counting each element density of sample solution automatically according to the working curve. The invention can detect the P element content in the PTA quickly, whose detecting precision is high.

Description

technical field [0001] The invention relates to the determination of metal content in crude (or refined) terephthalic acid. Background technique [0002] Terephthalic acid (PTA) is an important raw material for the production of polyester, and its quality directly affects the stable production and product quality of downstream polyester, and the content of metal elements is an important quality index of PTA products. Metal content The level not only reflects the production situation of the PTA unit, but also affects the quality and production of polyester products. In PTA products, if the metal content is too high, it will cause the formation of agglomerated particles in the polyester chips, so that it is easy to break the end during spinning. It is especially important that the presence of iron, chromium, nickel and other elements in PTA will cause corrosion of the device. Therefore, in order to produce qualified PTA products, the content of metal elements in PTA products...

Claims

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Application Information

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IPC IPC(8): G01N21/25G01N1/28
Inventor 陈家桢李德宏薛月霞许金林
Owner SINOPEC YIZHENG CHEM FIBER