Separation of ethanol/water azeotrope using compound starch-based adsorbents

Comparing breakthrough cures of five starch-based materials experimentally prepared for ethanol dehydration, a compound adsorptive agent ZSG-1 was formulated with high adsorption capacity, low energy and material cost. The selective water adsorption was conducted in a fixed-bed absorber packed with ZSG-1 to find the optimum conditions yielding 99.7 wt% anhydrous ethanol with high efficiency. The adsorption kinetics is well described by Bohart–Adams equation. The adsorption heat, ΔHabs, was calculated to be −3.16 × 104 J mol−1 from retention data by inverse gas chromatography. Results suggested that water entrapment in ZSG-1 is a exothermic and physisorption process. Also, ZSG-1 is recyclable for on-site multiple-use and then adapt for upstream fermentation process after saturation, avoiding pollution through disposal.