Enhanced Adsorption of Cd(II) and Pb(II) Using Amine-Modified MCM-41 Mesoporous Silica

Document Type : Research Article

Author

Department of Chemistry, Faculty of Science, Imam Khomeini International University, Qazvin, Iran

10.22091/jaem.2025.13195.1027

Abstract

This research investigates the synthesis and characterization of MCM-41 molecular sieves functionalized with 3-aminopropyltriethoxysilane (APTES) to evaluate their efficacy in adsorbing heavy metal ions, such as Cd(II) and Pb(II), from aqueous solutions. Amine-modified MCM-41 samples with 3, 5, 8, and 15 wt% APTES were synthesized via a co-condensation method using cetyltrimethylammonium bromide (CTAB) as the template, APTES for functionalization, and tetraethyl orthosilicate (TEOS) as the silica precursor. The adsorbents were characterized using X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms (BET), thermogravimetric analysis (TG-DTG), Fourier-transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). Batch adsorption experiments assessed the effects of initial metal ion concentration, solution pH, adsorbent dosage, and temperature. All NH2-MCM-41 variants exhibited higher adsorption capacities for Cd(II) and Pb(II) than unmodified MCM-41, with performance varying by amine loading. The enhanced adsorption was attributed to amine groups on the pore surfaces and external surfaces of the mesoporous silica. For the optimized adsorbent (5 wt% NH2-MCM-41), maximum adsorption efficiencies were 89.1% for Cd(II) at pH 5.0–6.0 and 95.3% for Pb(II) at pH 3.0–3.5, with precipitation effects considered negligible under these conditions. Adsorption isotherms conformed to the Langmuir model, indicating monolayer adsorption. Kinetic studies revealed that adsorption followed the pseudo-second-order model for both Cd(II) and Pb(II).

Keywords

Main Subjects

Advances in Energy and Materials Research
Volume 1, Issue 3
September 2024
Pages 40-54

Files

Share

How to cite

Statistics