Thermodynamics and kinetics of adsorption of Cu(II) onto waste iron oxide

Abstract

This study investigates low-cost sorbents as replacements for current costly methods of removing heavy metals from solution. This investigation explores the waste iron oxide material (F1), which is a by-product of the fluidized-bed reactor (FBR)–Fenton reaction, for use in the treatment of the wastewater in Taiwan. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the F1. In this investigation, F1 are tested as adsorbents for removing copper (Cu 2+) from aqueous solutions. The highest Cu 2+ adsorption capacity of F1 adsorbent was determined as 0.21 mmol g −1 for 0.8 mmol dm −3 initial Cu 2+ concentration at pH 6.0 and 300 K. Adsorption data were well described by the Freundlich model and the thermodynamic constants of the adsorption process, Δ G°, Δ H° and Δ S° were evaluated as −6.12 kJ mol −1 (at 318 K), 9.2 kJ mol −1 and 48.19 J mol −1 K −1 (at 318 K), respectively. Additionally, a pseudo-second-order rate model was adopted to describe the kinetics of adsorption.