Optimal design of a low-pressure SMB process for continuous separation of 3,6-anhydrogalactose from galactose with high productivity and high product concentration

Abstract

The feasibility of utilizing a simulated-moving-bed (SMB) process in “continuous separation of 3,6-anhydrogalactose (AHG) from galactose”, which is one essential task for promoting industrial production of AHG based on red algae, has been experimentally verified recently. To ensure the successful industrialization of the red algae-based AHG production, the aforementioned SMB process for AHG separation should be comprehensively optimized to maximize its economical efficiency, which is controlled mainly by the SMB productivity and AHG product concentration. As the first work for this study, a computerized optimization tool for handling a variety of SMB optimization variables (including operation parameters, column length, column-arrangement mode, and target product yield) was constructed based on standing-wave-design method, which was then utilized to maximize the SMB productivity while placing minimum and maximum acceptable limits on AHG product concentration and pressure drop respectively. It was found first that the highest SMB productivity could be achieved by selecting the SMB column length in a way that allowed both AHG product-concentration and pressure-drop requirements to limit the productivity simultaneously under the pre-set conditions of target AHG yield (YAHG) and column-arrangement mode (χ). It was also revealed that the SMB productivity could be improved further by (i) continuing to reduce YAHG until the positive effect of the YAHG reduction on AHG dilution ratio could be balanced with its negative effect on AHG recovery level, or (ii) adjusting χ in favor of the SMB enrichment zones for AHG product. The individual application of each strategy resulted in an additional 19% improvement in the SMB productivity, while the simultaneous application of both strategies resulted in an additional 38% improvement in the SMB productivity. The results of this paper will contribute to paving the way for the industrialization of AHG production based on marine-biomass utilization.