Solvated liquid-lignin fractions from a Kraft black liquor.
A softwood Kraft black liquor was acidified with carbon dioxide at 115°C and 6.2 bar over a pH range of 13.6-9.5, resulting in the precipitation of liquefied-lignin fractions as a separate phase. Seven such "liquid-lignin" fractions were produced, with each fraction being phase-separated within a narrow pH band of 0.5 units. The fractions were found to be highly hydrated phases, containing 32.3-48.2 wt.% water; as a result, their measured melting points were quite low, 90.7-110.5°C. In contrast, no melting point was detected up to 375°C for any of the lignin fractions after drying. Significant reductions in metals content were observed for the lignin fractions compared to the original black-liquor feed.
Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634-0909, USA.
Julian
J
Velez
Mark C
MC
Thies
D002245:Carbon Dioxide / Q000032:analysis; D005591:Chemical Fractionation; D011232:Chemical Precipitation; D004602:Elements; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000032:analysis*; D008031:Lignin / Q000737:chemistry*; D010209:Paper; D012997:Solvents / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry*
D002245:Carbon Dioxide; D004602:Elements; D007220:Industrial Waste; D008031:Lignin; D012997:Solvents; D062065:Wastewater
CO(2) acidification; Fractionation; Hydration; Lignin; Precipitation