Zeolite/calcium carbonate composite for a synergistic adsorption of cadmium in aqueous solution

• DOI: 10.1016/j.nxmate.2025.100493
• Publication Date: 2025-01-16T11:33:04Z
• Authors: Daniela O. Profeta; Marcella A. da Silva; Diêgo N. Faria; Daniel F. Cipriano; Jair C.C. Freitas; Fabiana Soares do...; Thiago M. Lima; Sancler C. Vascon...; Mendelssolm K. Pi...
• Keywords: Technology; CaCO3 impregnation; T; Faujasite; Beta zeolite; Cadmium removal

The present work describes the production of synthetic FAU-type zeolites, obtained from different silicon sources, and impregnated with CaCO3. The results showed that the dispersion of CaCO3 particles over the zeolite surface combined with its adsorption sites improved the performance of the adsorbents for Cd2 + removal in aqueous solution when compared to pristine zeolites. The commercial beta zeolite sample, used as a reference, revealed unsatisfactory performance on Cd2+ uptake since both the Al and Ca contents were lower than those found in the synthetic FAU-type zeolites. Adsorption tests, associated with kinetic studies and adsorption isotherms, revealed that chemisorption, especially ion exchange, with monolayer formation at the zeolite surface, was the main mechanism involved in the Cd2+ uptake process. These results showed then that it is necessary to impregnate the samples with CaCO3, since the Cd2+ removal efficiency is raised for all samples, possibly due to the synergistic contribution of the adsorption sites present in both the zeolite and the CaCO3 particles. Furthermore, the FAU-type zeolite sample with a larger crystal size or larger particle aggregate showed greater capacity to disperse the CaCO3 on its surface, enhancing the Cd2+ uptake.