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

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 (Cu²⁺) from aqueous solutions. The highest Cu²⁺ adsorption capacity of F1 adsorbent was determined as 0.21 mmol g^-1 for 0.8 mmol dm^-3 initial Cu²⁺ 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, ΔG°, ΔH° and ΔS° 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.