A novel nano-scaled zerovalent iron (nZVI) is an effective adsorbent for scavenging inorganic and organic toxicants. nZVI was synthesized in a single pot system using bottom-up approach and were characterized by BET, SEM, EDX and FTIR. In this study, sorption of Cu2+ onto nZVI was carried out vis-à -vis the investigation of physicochemical parameters (initial metal ion concentration, pH, temperature, adsorbent dose) at 298 K. The sorption data obtained at optimum conditions were subjected to six different isotherm models (Langmuir, Freundlich, Tempkin, Dubinin-Raduskevich (DRK), Halsey and Harkin-Jura). However, the equilibrium sorption data were best described by both Langmuir and Temkin isotherm models with Langmuir maximum monolayer coverage (Qmax) of 40.816 mg/g and regression correlation value (R2 > 0.96) supporting a chemisorption mechanism. Pseudo first-and second-order, Elovich, fractional power and intra-particle diffusion models were applied to the adsorption data in order to investigate the kinetic process; pseudo-second order fitted the data most. The intra-particle diffusion model suggested that the intra-particle diffusion was one of the rate-limiting steps. The values of the Gibbs free energy showed the feasibility and spontaneity of the sorption process. The removal efficiency of Cu2+ (> 98%) onto zerovalent iron nanoparticles revealed that nZVI is a promising and efficient adsorbent that can be utilized by industries on a large scale for waste treatment.
Keywords: Zerovalent Iron nanoparticles; Sorption; Isotherms; Kinetics and Thermodynamics