Black liquor (BL) concentration in the kraft process is extremely energy intensive due to the use of multi-effect evaporators. Membrane-based processes can save large amounts of energy, but the development of robust (long-lived) and high-performance membranes for BL concentration has remained elusive and has been highly challenging for conventional polymeric and ceramic membranes . We will discuss the ongoing development of graphene oxide (GO)-based membrane technology for BL applications at Georgia Tech . The fundamental methods for the synthesis and modification of these GO membranes will be illustrated, and the resulting separation properties such as permeation flux, lignin rejection, non-lignin organics rejection, inorganics rejections, and total solids rejection from BL feeds will be discussed in detail. The tuning of GO membranes to achieve nanofiltration (NF) and reverse osmosis (RO) performance will be demonstrated. Furthermore, the scale-up of GO membranes and their excellent performance in longer-term evaluation with realistic BL feeds (up to 3 gal/min) will be discussed. Finally, we will discuss the feasibility of a process that combines GO-based NF and RO membrane stages for concentration of BL as well as production of process-quality makeup water.
 N. Kevlich, M. L. Shofner, S. Nair, "Membranes for Kraft Black Liquor Concentration and Chemical Recovery: Current Progress, Challenges, and Opportunities", Separation Science & Technology, 52 (6), p. 1070-1094 (2017).
 F. Rashidi, N. Kevlich, S. Sinquefield, M. Shofner, S. Nair, "Graphene Oxide Membranes in Extreme Operating Environments: Concentration of Kraft Black Liquor by Lignin Retention", ACS Sustainable Chemistry & Engineering, 5, p. 1002-1009 (2017).