Development of a simulated moving bed process for ultra-high-purity separation of ribose from a low-selectivity sugar mixture in microalgal hydrolyzate

The ultra-high-purity separation of ribose from the mixture of monosugars coming from the hydrolysis of defatted microalgal biomass has been a core issue in the areas of microalgae-based ribose production process for pharmaceutical applications. To address such issue, this study was aimed at developing a customized simulated-moving-bed (SMB) process to steadily recover ribose with ultra-high purity from the aforementioned monosugar mixture. First, the intrinsic parameters of the mixture components containing ribose were determined through single-column experiments, which revealed the issue of a low selectivity between ribose and other impurities. On the basis of the determined intrinsic-parameters, the optimal design of the ribose-separation SMB was conducted in such a way that a proper degree of separation margin for maintaining an ultra-high level of ribose purity steadily throughout the SMB operation could be reflected in a quantitative manner while keeping the degree of the adsorbent-bed utilization as high as possible. These considerations were handled by carrying out the optimization runs of maximizing throughput while forcing the purity and yield constraints to be met not only in the normal situation (no deviations in adsorption parameters) but also in the situation where the adsorption parameters of all components would have a given range of fluctuations. The simulation and experimental works for such optimized ribose-SMB confirmed that it could lead to the continuous-mode separation of ribose with the purity of 99.6% without loss, and the degree of its adsorbent-bed utilization could be kept to the highest level when the worst cases of deviations in adsorption parameters would occur.