Dynamic simulation-driven analysis of cadmium, nickel, cobalt, and iron adsorption mechanisms in zeolite LTA synthesized from bentonite

Abstract

A practical and cost-effective method was successfully developed for synthesizing high-performance zeolite LTA from bentonite clay by fine-tuning activation steps and crystallization parameters. The optimal synthesis conditions and crystallization mechanism were investigated. The synthesized zeolites were characterized using XRD, FTIR, and SEM-EDS techniques. The results highlight the significant influence of factors such as crystallization temperature, duration, and the effect of sodium hydroxide concentration on the formation of zeolites. Optimal conditions set at a crystallization temperature of 97 °C, duration of 24 h, and NaOH concentration of 4M yielded pure zeolite LTA, boasting high crystallinity levels. Achieving a peak crystallinity of 82 %. The obtained zeolite LTA showed an exceptional Cd (II) ion exchange capacity. A mechanism involving adsorption of Cd 2 ⁺, Ni 2 ⁺, Co 2 ⁺, and Fe 2 ⁺ ions in zeolite LTA at the α and β-cages has been proposed using dynamic simulation. This mechanism supports all experimental results, in particular for LTA- Cd 2 ⁺, Cd 2 ⁺ ions are predominantly distributed in both α and β-cages, with a denser distribution in the α-cages, indicating a strong preference for these sites due to their geometric and electronic environment. The resulted zeolite LTA demonstrated ability for successful Cd (II) removal, affirming its utility as an efficient material in environmental remediation industries. • A practical and cost-effective synthesis of high-performance zeolite LTA from bentonite was developed. • Z_LTA adsorbent displayed high Cd(II) ion exchange capacity and selectivity. • Potential adsorption mechanism of metal ions in the α and β-cages of Z_LTA was elucidated using dynamic simulations. • Z_LTA adsorbent can be effectively reused for up to ten cycles.