Study of the Removal of Pb(II) Using a Weak Acidic Cation Resin: Kinetics, Thermodynamics, Equilibrium, and Breakthrough Curves

• Published in: Industrial & engineering chemistry research 2013-07, Vol.52 (26), p.9227-9238
• Main Authors: Vergili, Ilda, Soltobaeva, Gülzada, Kaya, Yasemin, Gönder, Z. Beril, Çavuş, Selva, Gürdaǧ, Gülten
• Format: Article
• Language: English
• Subjects: Cations; Fourier transforms; Ion exchangers; Isotherms; Polymers; Resins; Sorption
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie400630d

This study presents a method for the removal of Pb(II) from aqueous solution in batch and column modes using a commercial weak acidic cation (WAC) resin (Lewatit CNP80). Batch experiments carried out under different conditions yielded optimum conditions of pH = 5, t = 360 min, and m = 0.05 g (1 g L–1). The mechanism of ion exchange was studied using isotherm, kinetic, and thermodynamic models. The good fit of the Koble–Corrigan isotherm model indicates both heterogeneous and homogeneous sorption of Pb(II) on the resin. The concentration of Pb(II) in the solution had a strong influence on both the diffusion kinetics and the mechanism controlling the kinetic coefficient. The fit of the experimental data to the pseudo-second-order model indicated that the reaction is affected fundamentally by Pb(II) concentration, whereas temperature did not result in a significant change. The Gibbs free energy change (ΔG°) values were negative, corresponding to a spontaneous process of Pb(II) ion sorption onto the WAC resin. The S-shaped breakthrough curves from the column studies show that most of the resin capacity was used up to the breakthrough point. Clean and Pb(II)-loaded WAC resins were characterized on the basis of ζ-potential measurements, Fourier transform infrared spectrum (FTIR) spectral study, thermogravimetric analysis (TGA), and environmental scanning electron microscopy (ESEM) images. The O–H and C–O stretching of the carboxylic acid groups and the C–O–C stretching groups were the main functional groups of the WAC resin participating in the Pb(II) binding. A visible change in the surface morphology observed from the ESEM images showed some fouling, an indicator of the 28% irreversible loss of capacity after regeneration. It can be concluded that ion exchange with WAC resin is a satisfactory process for Pb(II) removal especially for low concentrations.