| 摘要 |
Phenols are recovered from waste liquors containing a phenol and aldehydes by the addition of a bisulphite in sufficient amounts to react with all the aldehyde present. The waste liquor at pH below 9.5, preferably 7-9.5 is treated to a steam stripping process, whereby the phenol volatilizes and the aldehyde is fixed as the bisulphite adduct. The steam and phenol vapour are separated, e.g. by passing through aqueous alkali solution, whereby the phenol is absorbed from the mixture. Prior to the addition of the bisulphite the pH of the waste liquor is preferably adjusted to 7/sB0.4. After removal of the phenol the steam may be recycled together with any oil vapours which may be present. The phenol recovered may be phenol itself or a homologue such as a cresol or xylenol.
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