Effect of adsorbent particle size and temperature on water-ethanol separation by starchy and cellulosic substrates

 Inverse gas chromatography was used to study the adsorption of water and ethanol on two starchy (cornmeal and wheatflour) and one cellulosic (wheat straw) substrate, in the temperature range 50–90  °C. Three particle size fractions of each substrate were investigated – 180–250 μm, 160–180 μm and 125–160 μm, denoted, respectively, by: 60–80 mesh, 80–100 mesh and 100-120 mesh. Values for the separation factor and for thermodynamic parameters, such as Gibbs free energy and enthalpy of adsorption, were calculated from the chromatographic retention data. The results showed that water was adsorbed more strongly than ethanol on all substrates, at all temperatures. In addition, it was found that lower temperatures were more favourable for the adsorption of both solutes. There was no significant difference between values of separation capacity of the three fractions of wheat straw. In contrast, the separation capacities of starchy materials with smaller particle sizes, i.e. 80–100 mesh and 100–120 mesh, were greater. The 100–120 mesh wheatflour fraction exhibited the highest separation at all temperatures.