Membranes for Kraft black liquor concentration and chemical recovery: Current progress,challenges, and opportunities |
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| Authors: | Nikita S. Kevlich Meisha L. Shofner |
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| Affiliation: | 1. School of Chemical &2. Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA;3. Renewable Bioproducts Institute, Georgia Institute of Technology, Atlanta, Georgia, USA;4. Renewable Bioproducts Institute, Georgia Institute of Technology, Atlanta, Georgia, USA;5. School of Materials Science &6. Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA |
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| Abstract: | Membranes can significantly reduce energy consumption during concentration of black liquor (BL) in the Kraft papermaking process, but the harsh conditions (pH ~12, 80°C–95°C, ~15 wt% solids) make this challenging. We elucidate challenges and opportunities for membranes in BL applications. We critically review membrane materials, processes, and operational modes investigated in the literature. Future advances will involve fabrication of higher-rejecting (≥95% lignin and inorganics), BL-resistant, NF, and RO membranes. Opportunities exist for molecular sieving and electrically driven membranes to recover other valuable chemicals such as carboxylic acids. We also discuss the economics of BL concentration with a single-stage membrane process. |
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| Keywords: | Black liquor Kraft process lignin removal membrane nanofiltration |
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