Kinetics and mechanisms of the adsorption of Pb(II), Cu(II) and Cd(II) onto ETS-10

Understanding adsorption kinetics and mechanisms play an instrumental role to determine the speed, efficiency, and pathways by which adsorbents remove pollutants. In this study, kinetics and mechanisms of the adsorption of Pb(II), Cu(II) and Cd(II) onto ETS-10 are investigated based on the combination of experimental, theoretical models (Langmuir, Freundlich, Sips, Pseudo-First-Order (PFO), Pseudo-Second-Order (PSO), Intraparticle diffusion (ID)), and modern analytical techniques (XRD, SEM-EDX, FT-IR and BET-BJH). Obtained results show that Sips models give the best fit with experimental data for three ions, while kinetic of Pb(II) adsorption follows PSO and kinetics of Cu(II) and Cd(II) uptakes follow ID models. The adsorption rates of Pb(II) > Cd(II) > Cu(II) during the diffusion process on the surface, whereas the ones of Pb(II) > Cu(II) > Cd(II) in the intraparticle diffusion process. The mechanisms of intraparticle diffusion, ion-exchange and complexion play mainly roles in the removal of Pb(II), Cd(II) and Cu(II).