Facile Fabrication and Characterization of Amine-Functional Silica Coated Magnetic Iron Oxide Nanoparticles for Aqueous Carbon Dioxide Adsorption
Md. Muhyminul Islam, Md. Abdur Rahman, Mohammad Ashraful Alam, Md. Mahbubor Rahman, O. Thompson Mefford, Anwar Ul‐Hamid, Jalil Miah, Hasan Ahmad
Abstract
High Resolution Image Download MS PowerPoint Slide Surface active amine-functionalized silica coated magnetic iron oxide nanoparticles were prepared by a simple two-step process for adsorbing CO 2 gas from aqueous medium. First, oleic acid (OA) coated iron oxide magnetic particles (denoted as Fe 3 O 4 -OA) were prepared by a simple coprecipitation method. Then, the surface of the Fe 3 O 4 -OA particles was coated with silica by using tetraethyl orthosilicate. Finally, aminated Fe 3 O 4 /SiO 2 -NH 2 nanoparticles were concomitantly formed by the reactions of 3-aminopropyl triethoxysilane with silica-coated particles. The formation of materials was confirmed by Fourier transform infrared spectral analysis. Transmission electron microscopic analysis revealed both spherical and needle-shaped morphologies of magnetic Fe 3 O 4 /SiO 2 -NH 2 particles with an average size of 15 and 68.6 nm, respectively. The saturation magnetization of Fe 3 O 4 /SiO 2 -NH 2 nanoparticles was found to be 33.6 emu g –1, measured by a vibrating sample magnetometer at ambient conditions. The crystallinity and average crystallite size (7.0 nm) of the Fe 3 O 4 /SiO 2 -NH 2 particles were revealed from X-ray diffraction data analyses. Thermogravimetric analysis exhibited good thermal stability of the nanoadsorbent up to an elevated temperature. Zeta potential measurements revealed pH-sensitive surface activity of Fe 3 O 4 /SiO 2 -NH 2 nanoparticles in aqueous medium. The produced magnetic Fe 3 O 4 /SiO 2 -NH 2 nanoparticles also exhibited efficient proton capturing activity (92%). The particles were used for magnetically recyclable adsorption of aqueous CO 2 at different pH values and temperatures. Fe 3 O 4 /SiO 2 -NH 2 nanoparticles demonstrated the highest aqueous CO 2 adsorption efficiency (90%) at 40 °C, which is clearly two times higher than that of nonfunctionalized Fe 3 O 4 -OA particles.