How to determine the sulfuric acid content in sulfate solutions containing iron, silicon, aluminum, and titanium metal ions
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There is currently an waste sulfuric acid solution resulting from chemical mineral processing, containing metal ions such as iron, aluminum, silicon, and titanium. It is necessary to determine the sulfuric acid content in waste acid, but due to the interference of metal ions, direct acid-base titration analysis results in large errors. I wonder what method can be used to eliminate the influence of metal ions in waste acid when the mass fraction of sulfuric acid is between 20% and 30% What can be used to precipitate and remove metal ions in the form of complexes?
Is it very difficult to directly measure sulfate ions? It can be determined using anion chromatography: the sample is neutralized with carbonate, most metal ions hydrolyze and form precipitates, while silicon forms an amorphous silicic acid gel; the sulfate ions can then be analyzed in the clear solution. The volumetric titration method or the barium sulfate gravimetric method can also be used. Most analyses require appropriate sample preparation.
It is methodologically feasible to analyze sulfate after removing cationic interferences using carbonates; however, the analysis of sulfate takes too long, so weight analysis should be avoided as much as possible.
Moreover, the main goal is to analyze the content of free sulfuric acid in this system; when analyzing sulfate ions, those present in metal ions such as iron and aluminum ions are also taken into account, so what is determined is not the actual sulfuric acid content.