Transient modeling of column adsorption–desorption processes for pre-concentration of D-1,2,4-butanetriol

Abstract D-1,2,4-Butanetriol (BT) is one of the important platform chemicals mainly used in the pharmaceutical and military fields. However, the content of BT in its fermentation broth is less than 1 wt%. The purification of BT by distillation is a high energy-consumption process. In this paper, a solvent desorption method was used to pre-concentrate BT with ethanol as a desorbent. This work focused on establishing a transient chromatographic column model to explore vividly the pre-concentration behaviors of BT during column adsorption/desorption processes. First, by analysis of the hydrophobicity and molecular size of the solutes and the micropore size of resin, the adsorption mechanisms were proposed as size exclusion and hydrophobic interaction, while desorption equilibrium was supposed to competitive adsorption. Secondly, the effects of the different ethanol concentrations on the enrichment of BT concentration were investigated systematically. The results showed about 1.46 bed volumes of absolute ethanol could desorb BT completely with 1.5 times BT concentration in the fixed bed system. Finally, a general rate model (GRM) was used to predict the dynamic adsorption/desorption processes successfully. The transient process of BT pre-concentration in the presence of desorbent ethanol was vividly displayed by Matlab, which revealed the individual behaviors of BT and ethanol during the adsorption/desorption process. It further proved the competitive adsorption could be the reason for the BT pre-concentration.