Method for indirectly measuring silicon content in defoaming agent through flame atomic absorption

Abstract

The invention discloses a method for indirectly measuring silicon content in a defoaming agent through flame atomic absorption. The method comprises the following steps of: (1) digestion: taking 0.3 to 0.5g of defoaming agent sample, and adding 8 to 10mL of 65 to 69 mass percent nitric acid for microwave digestion to obtain a digestion solution; (2) derivatization and extraction: adding a molybdate solution into the prepared digestion solution for derivatization reaction to obtain silicon molybdenum heteropolyacid, extracting to obtain a testing solution, performing nitric acid acidification on a standard solution of molybdenum, and performing derivatization and extraction by using the same method to obtain a standard solution extraction liquid; and (3) measurement on a machine through flame atomic absorption: introducing the testing solution and the standard solution extraction liquid into a flame atomic absorption spectrophotometer for measuring molybdenum content, comparing and quantitating, and converting the molybdenum content into silicon content. The method has the advantages of high antijamming capability, high responsiveness, high repeatability and low cost.

Description

technical field [0001] The invention relates to a method for the silicon content in the defoamer, in particular to a method for indirect determination of the silicon content in the defoamer by flame atomic absorption. Background technique [0002] Silicone defoamers are silicon-containing surfactants. As a family of organosilicon compounds, they have been used in various industrial fields since the 1960s, but their large-scale and comprehensive rapid development began in the 1980s. Silicone defoamer has many excellent properties: it can be miscible with water in any proportion, has excellent defoaming performance, and does not chemically react with foaming substances, non-toxic, non-polluting, harmless to the environment, heat-resistant, Cold resistance, aging resistance, excellent softness and lubricating properties, so silicone defoamers have a wide range of applications and are increasingly valued by all walks of life. [0003] At present, the main methods for determinin...

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Problems solved by technology

[0008] 5. Volatile silicon reduction weight method and potassium fluorosilicate volumetric method: These two methods are only suitable for the determination of silicon content in high-purity silicon (such as quartz) or alloys, and are not applicable to defoamers

Since silicon is a non-metal, it is difficult to be excited and ionized, so the response value on the instrument is very low, which is not conducive to the determination of low-concentration samples, and it has high requirements for sample pretreatment. It needs to be digested with hydrofluoric acid. The existence of the instrument will cause a certain memory effect, which is not conducive to the subsequent measurement and will affect the reproducibility of the measurement results

With hydrofluoric acid, the mass spectrometer must be replaced with more corrosion-resistant platinum cones, and even then, cone life is reduced

In addition, the high price and use cost of the instrument itself is also one of the weaknesses of this method

[0011] The atomization temperature of silicon is as high as 2800°C. It is very difficult to directly measure the atomic absorption method, the response value is extremely low, the sensitivity is poor, and the reproducibility is poor. The flame atomic absorption must use laughing gas / acetylene flame to reach such a temperature. Even so, ideal results cannot be obtained

[0012] The silicon volatile weight loss method and the potassium fluorosilicate volumetric method are only suitable for the determination of the silicon content of high-purity silicon (such as quartz). These two methods have higher requirements for the measurement object, requiring low impurity content and high silicon content. The defoamer does not meet the above two requirements, so it is not applicable

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