Chromatographic separation of ethyl-β-d-glucopyranoside and d-glucose with steady-state recycling chromatography

•Steady state recycling chromatography (SSR) was investigated.•A novel design method of SSR was presented.•The method is usable in systems with components having linear sorption isotherms.•Performance of SSR was investigated experimentally and by numerical simulations.•SSR was found to be more efficient than batch process in the chosen test system.

Mixed-recycle steady-state recycling chromatography (SSR) is an efficient and simple chromatographic process scheme that can be used to improve the separation efficiency of single-column batch process in binary separations. Despite many theoretical and numerical simulation studies, experimental investigations of the mixed-recycle SSR mode, which is the most straightforward to design and implement, are still rather scarce. In this work, the use of SSR was investigated under strongly non-ideal conditions. A novel design method for determining the cut times of the recycle fraction of SSR was derived for systems with components having linear sorption isotherms. This method allows determination of the cut times directly from chromatograms obtained with the batch process in the same operating conditions as would be used in SSR. The applicability of the method was investigated with chromatographic separation of ethyl β-d-glucopyranoside (BEG) and glucose. The performance of SSR was investigated experimentally and by simulations. The design method was found to be well applicable in this case as BEG and glucose fractions fulfilling the set purity requirements (98 wt% for both) could be obtained. SSR was found to be over 50% more efficient than the batch process with respect to specific productivities and water (eluent) consumption. Numerical optimization of SSR with respect to flow rate and column loading gave the same optimal operation point as was obtained experimentally. At this global optimum, SSR was 20% more efficient with respect to productivity than the batch process at its global optimum with a single cut separation, and only 14.5% less efficient than a 4-zone SMB (1:1:1:1 configuration). The results demonstrate the efficiency of SSR over batch process, and show that SSR is a viable option for 4-zone SMB process due to low investment costs and simple operation.