Kraft lignin ultrafiltration

Figure 7. Association of predissociated kraft lignin sample (92% retained by nominally 500 molecular weight cutoff ultrafiltration membrane) during incubation at 160 gL 1 in 1.0 M ionic strength aqueous 0.40 M NaOH for (l)0h, (2) 50 h and (3) 480 h.

Table 8.4.3. Molecular weight distribution of pine kraft lignin in black liquor measured by ultrafiltration...

Kirkman, A. G. Gratzl, J. S. Edwards, L. L. Kraft lignin recovery by ultrafiltration economic feasibility and impact on the kraft recovery system. Tappi J. 1986, 69(5), 110-114. 

Uloth V, Wearing J. Kraft lignin recovery acid precipitation versus ultrafiltration. Part I laboratory test results. Pulp Pap Can 1989 90(9) 67—71. 

Hill M, Fricke A (1984) Ultrafiltration studies on a kraft black liquor. Tappi J 67(6) 100-103 Klinkowski PR (1978) An emerging unit operation. Chem Eng 8 165-173 Lin SY, Detroit WJ 1981 Heterogeneity of technical lignins - its significance in lignin utilization. Proc 1981 Int Symp Wood Pulp Chem. Ekman-Days 1981 (Stockholm). SPCI Rep 38,4 44-52... 

Wallberg O, Jonsson A-S, and Wimmerstedt R. Fractionation and concentration of kraft black liquor lignin with ultrafiltration. Desalination 2003 154 187-199. 

Ristolainen, M. Alen, R. Knuutinen, J. Characterization of TCF effluents from kraft pulp bleaching. I. Fractionation of hardwood lignin-derived material by GPC and ultrafiltration. Holzforschung 1996, 50 (1), 91-96. 

Wallberg O, Jonsson A-S. Separation of lignin in kraft cooking liquor from a continuous digester by ultrafiltration at temperatures above 100°C. Desalination 2006 195(1—3) 187—200. 

Ullrafiltration processes have proved successful for the treatment of effluents, the treatment of black liquor, bleaching effluents and paper machine wash waters. They have also found use in the treatment of Kraft process effluents and there is increasing use of ultrafiltration to recover lignosulphonate and alkali lignin from the spent Uquors to produce other products. Reverse osmosis is used in the pulp and paper industry for concentration of sulphate liquor, using plate and frame modules and cellulose acetate membranes. Reverse osmosis is also used in the treatment of bleach effluents after various pretreatment stages. 

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