Discussion on particle alkali concentration analysis using a refractometer
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Our company has acquired a refractometer for analyzing concentrations such as 32% alkali, saltwater concentration, and hydrogen peroxide concentration. The analysis of the concentration of granular alkali in the control sample still uses the national standard methods: weighing, dissolving, making up to a fixed volume, and titration. The time required for analyzing one sample of granular alkali is around 40–50 minutes. To determine the concentration of granular alkali using a refractometer, we first dissolve the granular alkali to achieve a concentration of around 30%, and then use the refractometer to measure this concentration. It is necessary to accurately weigh the mass of the alkali, m1; after dissolution, the mixture is cooled to room temperature, and then the mass of the dissolved alkali solution is weighed, m2. The concentration of the alkali, c, can be determined using the refractometer, with w% calculated as cm2/m1. The values obtained using this method are 0.5% higher than those specified by the national standards; are there any better methods?
The refractometer should work well for measuring concentration; it’s just that when the concentration is high, temperature control is necessary. Furthermore, the online density meter method can also be considered, or the online titration method is more accurate and reliable.
This post was last edited by qugd on 2023-10-24 09:24. Acid-base titration is the standard method for determining the purity of caustic soda, as this analytical technique analyzes the alkalinity of sodium hydroxide. It is considered a **standard method due to its specificity and reliability in detection. The refractometry principle involves measuring the total refractive change caused by all components in the caustic soda solution that are capable of altering the refractive index of water; it is a relative analytical method, as caustic soda also contains a certain amount of sodium carbonate, which contributes to changes in the refractive index as well. The accuracy of acid-base titration is definitely reliable.
Actually, an refractometer works very well for measuring a 32% alkali concentration, giving results that are identical to those obtained through titration
We have used Anton Paar densitometers, those with a capacity of 20–30 watts; they are also very good for working with liquid alkalis
Could it be considered to compare the titration data with the refractometer measurement data in order to find a correction factor?
Most instruments have a data correction function; simply find the corresponding relationship and make the adjustment.