Fabrication and Characterization of SiO 2 /(3-Aminopropyl) triethoxysilane-Coated Magnetite Nanoparticles for Lead(II) Removal from Aqueous Solution Mahnaz Mahdavi • Mansor Bin Ahmad • Md Jelas Haron • Yadollah Gharayebi • Kamyar Shameli • Behzad Nadi Received: 6 November 2012 / Accepted: 7 January 2013 / Published online: 24 January 2013 Ó Springer Science+Business Media New York 2013 Abstract A novel nano-adsorbent SiO 2 /(3-amino propyl)triethoxysilane-coated magnetite nanoparticles was synthesized for the adsorption of lead ions from water samples. Its structure and magnetic characteristics were characterized, by FTIR, powder X-ray diffraction, scanning electron microscope (SEM), transmission electron micro- scope (TEM) and vibrating sample magnetometry (VSM). Amino-functionalized SiO 2 coated Fe 3 O 4 magnetite nano- adsorbent exhibited superparamagnetic behavior and strong magnetization at room temperature. The efficiency of the nano-adsorbent in separation of the metals was evaluated by adsorption technique. Kinetic data were analyzed using the pseudo-first-order and pseudo-second-order equations. The data fitted very well to the pseudo-second-order kinetic model.The linear Langmuir and Freundlich models were applied to describe equilibrium isotherms and Langmuir model fitted well. The monolayer adsorption capacity was found as 17.65 mg/g at pH 4.0. Thermodynamic parame- ters such as free energy change (DG°), enthalpy change (DH°) and entropy change (DS°) were also calculated. These parameters showed that the adsorption of Pb(II) onto nano-adsorbent was feasible, spontaneous and endother- mic. The amino-functionalized SiO 2 coated Fe 3 O 4 mag- netic nano-adsorbent shows high adsorption capability for metal ions from aqueous solutions via the chelation mechanisms. The Pb(II) loaded nano-adsorbent can be easily recovered from aqueous solution with magnetic separation and regenerated readily by acid treatment. The product of this work can be used as an effective and recyclable nano-adsorbent for the removal of metal ions in wastewater treatment. Keywords Magnetic nano-adsorbent  Fe 3 O 4 /SiO 2 composite nanoparticles  Adsorption  Amino- functionalization 1 Introduction Water pollution is a major environmental problem faced by modern society that leads to ecological disequilibrium and health hazards [1]. Extensive pollution of the environment by heavy metals leads to the imbalance in the natural equilibrium. Lead is one of the major environmental pol- lutants because of its presence in automobile fuel and subsequent emission into the atmosphere in the exhaust gases. Moreover, it penetrates to the water environment through effluents from lead smelters, battery manufactur- ers, paper and pulp industries, and ammunition industries M. Mahdavi (&)  M. B. Ahmad  K. Shameli Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia e-mail: mahnaz.chem@gmail.com M. Mahdavi Department of Polymer Engineering, Islamic Azad University, Shiraz, Iran M. J. Haron Centre of Foundation Studies for Agricultural Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia Y. Gharayebi Department of Chemistry, Islamic Azad University, Behbahan Branch, Behbahan, Iran K. Shameli Materials and Energy Research Center, 3177983634, Karaj, Iran B. Nadi Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (UKM), Bangi, Malaysia 123 J Inorg Organomet Polym (2013) 23:599–607 DOI 10.1007/s10904-013-9820-2