Method of separating lignosulphonic acids from aqueous liquids containing same

摘要

A method of separating alpha lignosulphonic acids from an aqueous liquid containing said acids comprises treating said liquid with minerally-tanned hide for a time sufficient to allow the chemical combination of said acids with said hide and then treating said hide with an aqueous alkali to remove said acids therefrom. In a modification of the process the aqueous liquid also contains beta lignosulphonic acids and after the removal of the alpha lignosulphonic acids, the liquid is again treated with tanned hide for a time sufficient to allow the chemical combination of said beta lignosulphonic acids with said hide and the hide is then treated with an aqueous alkali to remove the beta lignosulphonic acids therefrom. The hide may be re-used for the separation of the alpha- and beta acids after washing with an aqueous acid, e.g. dilute sulphuric acid. The hide may be employed in finely divided condition. The aqueous alkali specified is ammonium hydroxide. Sulphite liquor from the paper pulp process is the specified starting material. Examples are furnished.