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

Li-Al hydrotalcite-like compound (Li-Al Hllc) was synthesized via a hydrothermal method and used to adsorb Cu2+ and Zn2+ for investigating the adsorption characteristics of heavy metal cations. The X-Ray diffraction (XRD), folder transform infrared spectroscopy (FT1R), scanning electron microscope (SEM) and transmission electron microscopy (TEM) characterizations revealed the interconnecting flower-like layered structure of Li-Al Hllc. The adsorption kinetics and isotherms of Cu2 + and Zn2+ on Li-Al HTIc agreed with the pseudo-secondorder model and the Langmuir model at a given sorbent concentration (C-s), respectively. The C-s -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 C-s 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 Li-Al Hllc for the removal of heavy metal cations Cu2+ and Zn2+ from a solution. Li-Al HTIc is a promising sorbent for treating water containing heavy metal cations. (C) 2020 Elsevier B.V. All rights reserved.