title: Backfill-simulated moving bed operation for improving the separation performance of simulated moving bed chromatography.
abstract: The Backfill-SMB (BF-SMB) strategy was designed to improve the separation performance of simulated moving bed (SMB) chromatography. In the BF-SMB operation, a limited amount of products from raffinate and/or extract was re-fed to the SMB circuit as a backfill-feed. Two additional operating variables, backfill ratio (BR) and backfill length (BL), were suggested to determine the amount and injection length of backfill-feed. This strategy was applied to a four-zone SMB with one column (1-1-1-1) and two columns (2-2-2-2) per zone using a binary mixture with a nonlinear isotherm. Various BF-SMB operational methods were designed to supply backfill-feed to the feed node and/or intermediate node. The separation performances of conventional SMB and BF-SMB were compared in terms of purity, recovery, and eluent consumption. The BF-SMB successfully improved the separation performance of the conventional SMB because backfill-feed led to the rich condition of the main component at each product withdrawal node. Due to the 'TMB effect' caused by backfill-feed, the BF-SMB operation was more efficient in the 1-1-1-1 configuration than in the 2-2-2-2 configuration, showing maximum improvement of 5-7% purity and recovery from the performance of conventional SMB. In addition, partial recycling of eluent by backfill-feed resulted in a decrease in eluent consumption up to 10% even with improved purity and recovery in BF-SMB.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul 120-749, South Korea.
authors.forename: Kyung-Min
authors.initials: KM
authors.lastname: Kim
authors.forename: Chang-Ha
authors.initials: CH
authors.lastname: Lee
mesh_terms: D000327:Adsorption; D002853:Chromatography, Liquid / Q000379:methods*; D003198:Computer Simulation; D008956:Models, Chemical; D009038:Motion
keywords: Backfill; Nonlinear isotherm; Simulated moving bed; True moving bed