Morphological and Structural Properties of Amino-Functionalized Fumed Nanosilica and Its Comparison with Nanoparticles Obtained by Modified Stöber Method

Abstract

In industry, silica nanoparticles (NPs) are obtained by the fuming and the precipitation method. Fumed silica NPs are commonly used in the preparation of nanocomposites because they have an extremely low bulk density (160–190 kg/m3), large surface area (50–600 m2/g), and nonporous surface, which promotes strong physical contact between the NPs and the organic phase. Fumed silica has fewer silanol groups (Si–OH) on its surface than the silica prepared by the Stöber method. However, the number of –OH groups on the fumed silica surface can be increased by pretreating them with sodium hydroxide (NaOH) before further surface modification. In this study, the effectiveness of the NaOH pretreatment was evaluated on commercial fumed silica NPs with a surface area of 200 m2/g. The number of surface –OH groups was estimated by potentiometric titration. The pretreated fumed NPs, and the precipitated NPs (prepared by the Stöber method) were modified with 3-aminopropyltriethoxysilane (APTES) to obtain A200S and nSiO2-APTES, respectively. The NPs were characterized using electron dispersive scanning (EDS), scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), BET (Brunauer–Emmett–Teller) analysis, and ζ-potential. XRD confirmed the presence of the organo-functional group on the surface of both NPs. After the amino-functionalization, the ζ-potential values of the nSiO2 and A200 changed from −35.5 mV and −14.4 mV to +26.2 mV and +11.76 mV, respectively. Consequently, we have successfully synthesized functionalized NPs with interesting, specific surface area and porosity (pore volume and size), which can be attractive materials for chemical and energy industries.

Efficient Method for the Concentration Determination of Fmoc Groups Incorporated in the Core-Shell Materials by Fmoc–Glycine

“…The second step leads to the condensation of organosilanols with hydroxyl groups present on the modified NPs surface. In this step, the condensation process also occurs [ 28 ]. The mechanism of action for APTES is based on the reaction with the hydroxyl group of the oxidized surface by SN2 exchange and loss of ethanol.…”

Enzyme-functionalised, core/shell magnetic nanoparticles for selective pH-triggered sucrose capture

“…This can be explained by the reduction in hydrogen bonding between silanol groups on the NPs' surface. 75 Therefore, the functionalisation steps helped to prevent the aggregation of the nanomaterial in water suspensions. The surface charge was also estimated through zeta potential measurements ( Table 1 ), and the size and shape of the nanomaterial were evaluated by TEM, as shown in Fig.…”

Synthesis and testing of polyacrylamide‐grafted waste sand derived composite adsorbent for water purification

“…The ASPs were mixed with 100 mL of 1 M aqueous solution of NaOH. The dispersions were stirred continuously using a magnetic stirrer at 60–70°C for approximately 12 h. ASPs were recovered by centrifugation at 5000 rpm and then washed four to five times with distilled water and dried in the oven for 24 h at 100°C 32 …”