Kinetic, thermodynamic and isotherm investigations of Cu2+ and Zn2+ adsorption on Li[sbnd]Al hydrotalcite-like compound
2020
Zhao, Ling-Xi | Liang, Ji-Ling | Li, Na | Xiao, Hua | Chen, Li-Zong | Zhao, Ru-Song
LiAl hydrotalcite-like compound (LiAl HTlc) was synthesized via a hydrothermal method and used to adsorb Cu²⁺ and Zn²⁺ for investigating the adsorption characteristics of heavy metal cations. The X-Raydiffraction (XRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscopy (TEM) characterizations revealed the interconnecting flower-like layered structure of LiAl HTlc. The adsorption kinetics and isotherms of Cu²⁺ and Zn²⁺ on LiAl HTlc agreed with the pseudo-second-order model and the Langmuir model at a given sorbent concentration (Cₛ), respectively. The Cₛ-effect on the adsorption kinetics and isotherms was observed, and the Langmuir–surface component activity (SCA) equation could be utilized to characterize the effect of Cₛ in the adsorption isotherms. The adsorption process was spontaneous and endothermic. The adsorption mechanism denoted that the adsorption process was controlled using two main mechanisms, i.e., surface complexation and isomorphic substitution. This is the first report, to the best of our knowledge, on the usage of LiAl HTlc for the removal of heavy metal cations Cu²⁺ and Zn²⁺ from a solution. LiAl HTlc is a promising sorbent for treating water containing heavy metal cations.
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