CO2 Sequestration by Natural Zeolite for Greenhouse Effect Control

This paper describes the adsorption of CO2 on pores in natural erionite exchanged with aqueous solutions of Na+, Mg2+, and Ca2+ salts at different concentrations, variable time and temperature of treatment. Experimental data of CO2 adsorption were treated by the Freundlich and Langmuir equations. Complementarily were evaluated standard adsorption energies and the degree of interaction of the gas with the zeolite; the evolution of isosteric heats of adsorption was analyzed. The exchange with Na+ favors the creation of emergent pores thus causing an increase of the adsorption capacity for CO2. The presence of Na+ at micropore entrances causes an increased adsorption into the nanocavities and on the external area of the ion-exchanged zeolites. The development of nanopores in erionite was evaluated through the Barrett-Joyner-Halenda and NLDFT methods. Depending on the conditions of the exchange treatment, Na+ was found to be most favorable, well distributed, and accessible for N2 adsorption.