文摘
The adsorption isotherm data of glycerol from biodiesel (FAME, fatty acid alkyl esters) onto the sulfonated adsorbent were obtained via batch equilibrium tests at different temperatures in the range of 303鈥?23 K. Subsequently, these data were fitted by four isotherm models. Freundlich isotherm model was the best fitted (r2 > 0.98), and the model parameter 1/n implied that the adsorption process was favorable. For the Dubinin鈥揜adushkevich (D-R) isotherm model, the model parameter QD decreased with increasing temperature, and the mean free energy of sorption (E) was less than 8 kJ mol鈥?. The results of QD and E reflected the exothermic and physical properties of the adsorption process, respectively. The negative values of Gibbs free energy change (螖G0) and enthalpy change (螖H0) indicated that the adsorption occurs spontaneously with an exothermic nature, while the positive values of entropy change (螖S0) suggested the increase in randomness at the solid鈥搇iquid interface during adsorption. The isosteric heat of adsorption (螖HX) suggested that strong hydrogen bonding between glycerol and the 鈭扴O3鈥?/sup> groups of the sulfonated adsorbent dominated the adsorption process and that there existed adsorbate鈥揳dsorbate mutual attractive interaction. Furthermore, the existence of hydrogen bonding was also confirmed by infrared spectra.