Analysis method for sulfate in saline water
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Our method for analyzing sulfate in saline involves EDTA titration, with a blank control used as a reference. When analyzing the data collected over a week, we notice large fluctuations, which results in inaccurate analysis. Do any of the more experienced colleagues have any better methods for analysis?
This post was last edited by zjp on 2010-10-19 at 15:39. The gravimetric method can also be used, but there are certain conditions for its application: Scope of application: This method is suitable for determining sulfate ions in raw water, circulating water, and boiler water whose polyphosphate content is less than 10 mg/L; the measurement range is 20–200 mg/L.
Moderator, the sulfate content in saltwater ranges from 4 to 10 g/l. Can this method be used? If so, could you provide the specific procedure or the relevant standard numbers? Thank you!
Our method involves taking 5 ml of the sample into a conical flask, adding 50 ml of distilled water, acidifying it with 1–2 drops of hydrochloric acid, then adding exactly 15 ml of a mixture of barium chloride and magnesium chloride. The mixture is heated to a gentle boil on an electric stove for three minutes; after cooling to room temperature, 5 ml of triethanolamine, 10 ml of an ammonium chloride-ammonium hydroxide buffer solution, 3–5 drops of chromium black T indicator, and 10 ml of ethanol are added. The solution is then titrated using a 0.05 mol/L EDTA standard solution until a pure blue color is achieved; a blank test is also conducted simultaneously.
Was the poster’s problem solved?:) Complex titration is quite accurate, right! What I want to ask is: you only conducted the statistics for one week – why do you think the method is inaccurate? Could it be a problem with the standard solution or some other reagent? If you have mature factories and analysis methods, problems wouldn’t arise within just a week! Is the reason for the large fluctuations operational or something else? Was it determined that it was a methodological issue, which is why the analysis method was changed? :) Ordinary chlor-alkali plants surely carry out the determination of sulfate in brine! :), is it somewhat useful as a reference, hehe
Judging from the sulfate content in the owner’s sample, it is no problem to use complexometric titration for determination. However, for industrial samples, especially in the process of preparing and refining chlor-alkali chemicals, it is entirely possible for the data to fluctuate. Currently, the methods for analyzing impurities in brine in the chlor-alkali process, especially those for analyzing sulfate ions, are highly reliable and well-established. If the original poster indeed has doubts about the data analysis, ion chromatography can be used to analyze the samples in order to verify the complexometric titration method. Also, check whether there are any factors related to the sampling containers and the sampling process that could affect the measurement results, or whether recent drops in temperature have had an impact on them.
I find this problem strange as well; after taking samples of sulfate, the values increase after one or two days. Could this be related to the decrease in solubility as the temperature drops? What I don’t understand is why, given the decrease in solubility, the measured amount of sodium sulfate actually increases