Trapping the lead ion in multi-components aqueous solution by natural clinoptilolite

Abstract

To study whether natural clinoptilolite could selectively capture Pb 2+ ion in the aqueous solution containing salt and glycine as well as nitrosamines, the natural zeolite was utilized in the complex solution with pH value of 1.2 in comparison with other porous materials such as zeolite NaZSM-5 and activated carbon. Clinoptilolite exhibited the highest capability in adsorbing Pb 2+ ion in the solution at 37 °C, achieving the capacity of 7 mg/g, two times more than that by other zeolites and six times over that by activated carbon, and the adsorption equilibrium could be achieved within 2 h. The impacts of solid–liquid ratio, initial concentration of Pb 2+ and the competition of other metal ions or volatile nitrosamines on the adsorption were examined, and the change in Gibbs energy for the ion-exchanged of Pb 2+ ion by clinoptilolite was discussed, through which the ion-exchange process was proven to be spontaneous. Moreover, both the selectivity of clinoptilolite toward Pb 2+ ion in complex solution and the venial toxicity of clinoptilolite on the viability of RAW264.7 cells were investigated in this article.