Avaluadó de la reacdó-adsordó de ions Ca²⁺ en cendres de bagàs de canya de sucre. Aproximacions cinètiques i termodinàmiques

The adsorption of Ca²⁺ ions and the pozzolanic reaction between ashes from sugar cane bagasse (bio-reactant) and Ca(OH)₂, are studied in the present paper. The characterization of the bio-reactant by means of XRD, specific surface Brunauer-Emmett-Teller (BET), thermal differential analysis (TDA), thermo-gravimetric analysis and other physical parameters such as pignometric density, porosity, compressibility, form factor and flow velocity, is developed. A four stages mechanism is proposed to describe the pozzolanic reaction according to Zhulaev postulations. Once the reaction takes place, an 85.15% of Ca²⁺ is converted and the rest remains as adsorbed specie validating a dual adsorption-reaction process. The kinetics of the adsorption process can be described by means of a pseudo-first order model and the mechanism is controlled by the film diffusion model. The thermodynamics of the adsorption process fits to the Freundlich isotherm.