What impurities are removed by coal tar acid washing?
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As the title suggests, which impurities are being removed? Must it be 95% sulfuric acid? Can waste acid from chlorine production be used?
Remove basic compounds such as pyridine, quinoline, etc. Concentrated sulfuric acid is not necessarily required, but the concentration should be around 15–17%.
Generally, during the distillate washing process, acid washing is carried out first followed by alkali washing; acid washing helps to remove substances used in the production of quinoline derivatives, while alkali washing helps to remove the crude powder
As far as I know, if the pyridine content is higher than that of phenol, acid washing should be done first; if phenol is present in higher amounts, alkali washing should be done first. Low-temperature coal tar mainly contains phenols, with very few basic compounds. Hehe, thanks anyway!