Treatment of industrial glycerol from biodiesel production by adsorption operation: kinetics and thermodynamics analyses

Abstract

Equilibrium, thermodynamic, and kinetic analyses of the pigments adsorption of the industrial glycerol onto activated charcoal were performed. As the pigments concentration was not known, then, a relative adsorption capacity was defined using absorbance values measured in a spectrophotometer at a wavelength of 265?nm. Kinetic study showed that about 60?s were needed to reach equilibrium conditions. Relative adsorption capacity reached 8?g^?1 for 1% of adsorbent amount (w/w). Adsorption enthalpy was of –17.63?kJ mol^?1, while for isosteric heat values were obtained between –7.39 and –18.46?kJ mol^?1. The mathematical methodology used for the parameters determinations proved to be robust and able to express the relationships of kinetics, equilibrium and thermodynamics. Enthalpy values obtained by Van't Hoff method was confirmed by isosteric heat calculation, evidencing that this methodology can be used for systems whose compositions are unknown, but detectable by indirect form.