Zhengzhou DEERXIN Tungsten & Molybdenum Technology Co., Ltd.
How to Determine Silicon Content Using the Molybdenum Blue Spectrophotometric Method
2025/04/25
The molybdenum blue spectrophotometric method is a commonly used technique for determining silicon content. The following are the basic steps for measuring silicon content:
First, the sample to be tested undergoes preliminary treatment. For solid samples, such as roasted molybdenum concentrate, the sample needs to be crushed and passed through a sieve with a specific mesh size, then dried at a particular temperature until a constant weight is achieved. Next, a certain amount of the sample is weighed and placed in a digestion apparatus, where it is digested using a mixture of nitric acid and hydrofluoric acid, or alternatively, melted and decomposed using sodium hydroxide, to obtain a silicon-containing solution.
Next, ammonium molybdate is added to the solution, forming silicomolybdic yellow with silicon. Then, a mixed acid of oxalic acid and sulfuric acid is added to increase the acidity and eliminate interfering elements. Finally, ascorbic acid is used to reduce the silicomolybdic yellow back to silicomolybdic blue.
Next, use a spectrophotometer to measure the absorbance of the solution at a specific wavelength (such as 800 nm or 810 nm). Prior to this, it is necessary to construct a calibration curve for silicon, so that the corresponding silicon concentration can be determined from the measured absorbance. To construct the calibration curve, take a series of standard solutions with known silicon concentrations, carry out the color development reaction according to the procedure described above, and then measure their absorbances. Finally, plot the calibration curve with the silicon mass on the x-axis and the absorbance on the y-axis.
Finally, based on the measured absorbance, determine the corresponding silicon content from the standard calibration curve and calculate the mass fraction of silicon in the sample.
The above are the basic steps for determining silicon content using the molybdenum blue spectrophotometric method. In actual practice, it is important to carefully control the experimental conditions to ensure the accuracy of the results.
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