| 摘要 |
Sulfite spent liquor is subjected to a two-step chromatographic separation to form substantially purified fractions of sugars and lignosulfonates. The process for the separation of sugars and lignosulfonates comprises the steps of (a) introducing sulfite spent liquor with a pH of 2.5 to 3.5 onto a chromatographic column containing a resin in metal salt form; (b) eluting the sulfite spent liquor from the column with water to recover a substantially sugar-free lignosulfonate-rich fraction and a sugar-rich fraction; (c) collecting the sugar-rich fraction for further purification; (d) adjusting the pH of the collected sugar-rich material to between 5.5 and 6.5 and introducing the material onto a second chromatographic column containing a resin in monovalent salt form; and (e) eluting the sugar-rich material from the second column with water, whereby a second sugar-rich fraction and a second lignosulfonate-rich fraction are formed. By this method, essentially all of the lignosulfonate is recovered in fractions which are substantially free of sugars, and essentially all of the sugars are recovered in a fraction which is substantially free of lignosulfonates. |
