Kinetic, thermodynamic and isotherm investigations of Cu2+ and Zn2+ adsorption on LiAl hydrotalcite-like compound.

ABSTRACT

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.