| abstract |
Crude hydroxyacetic acid made by the carbonylation reaction of formaldehyde and water in the presence of an organic acid and sulfuric acid is purified by the following steps. The crude acid is first treated with granulated activated carbon for decolorization, then treated in a weak anion resin column to remove the sulfuric acid, subjected to live steam stripping to remove low-boiling impurities, and finally treated with a cation exchange resin to remove metals present, e.g., iron or copper. |