Kinetics of Isothermal Ethanol Adsorption onto a Carbon Molecular Sieve under Conventional and Microwave Heating

The isothermal kinetics of ethanol adsorption from aqueous solution onto a zeolite type carbon molecular sieve (CMS-3A) under conventional heating (CH) and microwave heating (MWH) was investigated. The adsorption kinetics is described by the model of a phase-boundary controlled reaction for both heating modes. The activation energy (Ea) for the adsorption process under MWH is lower than under CH while the preexponential factor (lnA) is higher. Ethanol adsorption is a kinetically complex process whose complexity changes with the mode of heating. The established decrease in Ea and increase in lnA under MWH compared to CH is explained with the increase in the ground vibrational level of the OH twisting vibrations in the ethanol molecule and with the decrease in its anharmonicity factor which is caused by the selective resonant transfer of energy from CMS-3A to the OH oscillators.