Abstract
Lignin was extracted by ultrafiltration from kraft cooking liquors taken directly from a continuous digester. The temperature of the liquors was 145 degrees C (softwood) or 135 degrees C (hardwood), the total dry solids content was 18% and the pH 13-14. Methods for start-up, shut-down and cleaning of conventional UF equipment modified for this demanding application, were developed. The influence of transmembrane pressure, cross-flow velocity and temperature on the performance of two ceramic membranes with cut-offs of 5,000 and 15,000 Da was studied. The flux of softwood liquor at 145 degrees C and a TMP of 400 kPa was 100 l/m(2) h for the membrane with the 15,000 Da cutoff and 50 l/m(2) h for the membrane with the 5,000 Da cut-off. The retention of lignin was 20% and 30% for the 15,000 Da and 5,000 Da membranes, respectively.
Original language | English |
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Pages (from-to) | 187-200 |
Journal | Desalination |
Volume | 195 |
Issue number | 1-3 |
DOIs | |
Publication status | Published - 2006 |
Subject classification (UKÄ)
- Chemical Engineering
Free keywords
- high
- temperature
- ceramic membranes
- ultrafiltration
- Kraft cooking liquor
- lignin