Water and ethanol adsorption on starchy and cellulosic substrates as biomass separation systems

Abstract

 Adsorption of water and ethanol on to one cellulosic and five starchy materials of constant particle size has been studied in the temperature range of 50 – 90°C using inverse gas chromatography (IGC). The results showed that all substrates adsorbed water to a greater extent than ethanol, at all temperatures. On the other hand, the type of adsorber affected the adsorption of water more significantly than that of ethanol. Starchy materials showed a greater separation capacity compared to the cellulosic material. From the chromatographic retention data it was possible to calculate the separation factors for the two solutes and to obtain values for thermodynamic parameters such as Gibb’s free energy (ΔGs) and the enthalpy (ΔHs) of adsorption of water and ethanol on to the substrates. Calculated ΔGs values revealed that the adsorption of both solutes was more spontaneous at lower temperatures, as expected. The ΔHs values obtained for water were significantly higher than those for ethanol, indicating stronger water/substrate interactions. Wheatflour of 70% rate extraction proved to be the substrate with the highest separation factor at all temperatures.