Issue 46, 2015

Removal of Pb(ii) from aqueous solution by mesoporous silica MCM-41 modified by ZnCl2: kinetics, thermodynamics, and isotherms

Abstract

A new hybrid nanostructured sorbent ZnCl2-MCM-41, was synthesized by a post-synthesis method in toluene as the solvent. To characterize the sorbent, a number of methods were applied, including X-ray diffraction (XRD), nitrogen adsorption–desorption isotherm, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Characterization demonstrated that the sorbent particles are of semi-spherical shape, nanostructured with a 754 m2 g−1 surface area and a 2.86 nm pore diameter. The Pb(II) removal depended on several parameters, including the pH of solution, temperature, initial Pb(II) concentration, sorbent dosage, ionic strength, and the amount of ZnCl2 loaded on the MCM-41 surface. The results showed that the pseudo-second-order model describes the kinetics of sorption better than the pseudo-first-order model. The adsorption continuously increased in the pH range of 2.0–7.0, beyond which the adsorption could not be carried out due to the precipitation of the metal ions. The adsorbent had a considerably high Langmuir monolayer capacity of 479 mg g−1. The adsorption process was exothermic at ambient temperature and the computation of the parameters ΔG°, ΔH°, and ΔS° indicated the interactions to be thermodynamically favorable.

Graphical abstract: Removal of Pb(ii) from aqueous solution by mesoporous silica MCM-41 modified by ZnCl2: kinetics, thermodynamics, and isotherms

Supplementary files

Article information

Article type
Paper
Submitted
20 Jan 2015
Accepted
17 Apr 2015
First published
17 Apr 2015

RSC Adv., 2015,5, 37066-37077

Author version available

Removal of Pb(II) from aqueous solution by mesoporous silica MCM-41 modified by ZnCl2: kinetics, thermodynamics, and isotherms

F. Raji, A. Saraeian, M. Pakizeh and F. Attarzadeh, RSC Adv., 2015, 5, 37066 DOI: 10.1039/C5RA01192B

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