processes Review Systematic Review on Isolation Processes for Technical Lignin Marlene Kienberger *, Silvia Maitz, Thomas Pichler and Paul Demmelmayer Institute of Chemical Engineering and Environmental Technology, Graz University of Technology, Inffeldgasse 25c, A-8010 Graz, Austria;
[email protected] (S.M.);
[email protected] (T.P.);
[email protected] (P.D.) * Correspondence:
[email protected]; Tel.: +43-031-6873-7484 Abstract: Technologies for the isolation of lignin from pulping process streams are reviewed in this article. Based on published data, the WestVaco process, the LignoBoost process, the LigoForce SystemTM and the SLRP process are reviewed and discussed for the isolation of lignin from Kraft black liquor. The three new processes that have now joined the WestVaco process are compared from the perspective of product quality. Further, isolation processes of lignosulfonates from spent sulfite liquor are reviewed. The limitation for this review is that data are only available from lab scale and pilot scale experiments and not from industrial processes. Key output of this paper is a technology summary of the state of the art processes for technical lignins, showing the pros and cons of each process. Keywords: Kraft lignin; lignosulfonates; lignin isolation processes; technical lignin 1. Introduction Citation: Kienberger, M.; Maitz, S.; After cellulose, lignin is the second most abundant biopolymer worldwide. Lignins are Pichler, T.; Demmelmayer, P. non-toxic and renewable, and hence may play an essential role during the change-over from Systematic Review on Isolation a fossil-based to a bio-based economy. The value-added application of technical lignin not Processes for Technical Lignin.