Characterization of Biomass Adsorbent ZSG-1 through Isopropanol and Water Azeotrope Dehydration

Abstract

In this work, a compound starch-based adsorbent material known as ZSG-1, which was formulated in a previous work for high-capacity, low-cost ethanol dehydration, was thermodynamically assessed through dehydration of azeotropic aqueous isopropanol. Comparisons of the retention times, heats of adsorption (ΔH s ), and Gibbs free energies (ΔG) of isopropanol and water confirmed the feasibility of using ZSG-1 in this dehydration process. Retention data were obtained by inverse gas chromatography and revealed the heat of adsorption ΔH s to be −55.73 kJ/mol, demonstrating that water entrapment in ZSG-1 is an exothermic physisorption process. After SEM observation, the inner micrographic pore size and surface area of ZSG-1 were calculated and estimated using an approach that combines nitrogen adsorption and mercury porosimetry. Through tests in a fixed-bed column under conditions determined by orthogonal experiment design, the optimal adsorption conditions were determined from breakthrough curves at different bed depths, bed temperatures, and kettle temperatures.