Adsorption of Cu(II) onto three types of engineering materials in the presence of S,S-EDDS chelate: equilibrium, kinetics, and thermodynamics

Abstract

The adsorption of Cu(II) ions in the presence of the S,S-ethylenediaminedisuccinic acid (S,S-EDDS) chelating agent was investigated to determine the adsorption characteristics of the 719 strongly basic anion exchange resin (719 resin), γ-Al₂O₃, and activated carbon (AC). The influence of adsorption pH (3–7), time (10–600 min), initial concentration (25–175 mg/L), and temperature (298–318 K) was determined. A mechanism for the adsorption process was proposed. The adsorption data were fitted to the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich models. Batch experiments revealed that the maximum adsorption capacities are 17.46, 5.79, and 5.46 mg/g for the 719 strongly basic anion exchange resin, γ-Al₂O₃, and AC, respectively, at pH 6. The results also indicate that the Langmuir and Temkin adsorption models described the adsorption of Cu(II) ions onto the 719 strongly basic anion exchange resin, γ-Al₂O₃, and AC better than the Freundlich model. The obtained results show that a pseudo-second-order model describes the adsorption kinetics better than the other models for the three types of engineering materials. Thermodynamic constants for adsorption such as ∆H° and ∆S° were also calculated and we found that Cu(II) complex adsorption onto three types of engineering materials is an endothermic and spontaneous process.

Keywords:

• Adsorption
• Copper (II)
• S,S-EDDS
• Kinetics