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Lowering kraft black liquor viscosity of ultrafiltration

Conference · · Sep. Sci. Technol.; (United States)
OSTI ID:5995878
High viscosity is a major factor limiting the percentage total dissolved solids (%TDS) to which kraft black liquor (KBL), a spent pulping liquor, can be concentrated before it is burned to recover its fuel value and its inorganic chemicals. The effect on black liquor viscosity of removing high molecular weight lignin by ultrafiltration of 16% and 24% TDS liquors was studied. Viscosities of ultrafiltration permeates were reduced relative to feed black liquors. When a permeate was concentrated to higher %TDS levels, its viscosity decreased yet further relative to feed samples evaporated to similar solids levels. Retentate viscosity was very high relative to both feed and permeate. Ultrafiltration was carried out at 75/degrees/C using polysulfone membranes in a plate-and-frame or hollow fiber system. Flux rates varied greatly depending upon the specific liquor used. Flux was enhanced by increased temperature and increased linear velocity. The membrane molecular weight cutoff (MWCO) typically used was 50,000; increasing 100,000 or 200,000 did not enhance flux.
Research Organization:
Univ. of Maine, Orono, ME (USA)
OSTI ID:
5995878
Report Number(s):
CONF-871038-
Conference Information:
Journal Name: Sep. Sci. Technol.; (United States) Journal Volume: 23:12,13
Country of Publication:
United States
Language:
English