Lignin Concentration by Nanofiltration and Precipitation in a Lignocellulose Biorefinery
Weinwurm, F.
Drljo, A.
Friedl, A.
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Weinwurm F., Drljo A., Friedl A., 2015, Lignin Concentration by Nanofiltration and Precipitation in a Lignocellulose Biorefinery, Chemical Engineering Transactions, 45, 901-906.
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In the presented work, some findings of three separate studies were combined. These experimental and process simulation works included one study regarding the production of organosolv liquors to investigate lignin and carbohydrate solubilisation and the precipitation of lignins, one study investigating the nanofiltration behaviour of organosolv liquors, which were approximated with synthetic solutions of Kraft lignin and glucose, and third, a process simulation of the whole organosolv process to investigate possibilities for process integration and energy and chemicals savings. Here, we want to concentrate on the possibilities of concentrating the organosolv liquor by nanofiltration for lignin separation and production. A liquor with a lignin concentration of 9.1 g/L and a total monomeric sugar concentration of 61.8 mg/L was produced by ethanol organosolv treatment at 180 °C. The synthetic liquor which resembled these conditions the most had concentrations of 1.1 %w lignin and 0.1 %w glucose. With this liquor, a lignin rejection of ca. 99 % was reached. In the process simulation, which was done at an earlier stage, a lignin rejection of 90 % was used. This could mean a much lower "loss" of lignin to the permeate and a higher lignin yield in the precipitation step.
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