Insights into the physicochemical characteristics from vermiculite to silica nanosheets

Mesoporous silica nanosheets (SiNSs) were prepared from acid-treated vermiculite (Verm). The influences of acid concentration and reaction time on the structural, and textural properties of acid-treated samples were investigated. The physicochemical characteristics of SiNSs were studied by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR), N-2 adsorption-desorption techniques, zeta potential, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and Si-29 and Al-27 nuclear magnetic resonance (NMR). XRF study indicated that acid-treatment leads to the removal of the aluminum and magnesium from the octahedral sheets along with other impurities. XRD, SEM and HRTEM measurements supported that treatment with moderate concentrated acid and reaction time favor the formation of translucent and monodispersed SiNSs, which have been reported rarely. Acid-activation with 2 M HCl for 12 h gave a maximum value of specific surface area (764 m(2) g(-1)) with zeta potential of -38.9 mV. FTIR and NMR spectroscopic analyses demonstrated the formation of active groups (Si-OH groups) on the surface of SiNSs. The SiNSs thus obtained by acid-treatment can be used as promising catalyst supports, adsorbents, and morphology-controlling reagents of nanomaterials. (C) 2016 Elsevier B.V. All rights reserved.