Impacts of Green Synthesis Process on Asymmetric Hybrid PDMS Membrane for Efficient CO2/N2 Separation

The effects of green processes in hybrid polydimethylsiloxane (PDMS) membranes on CO2 separation have received little attention to date. The effective CO2 separation of the membranes is believed to be controlled by the reaction and curing process. In this study, hybrid PDMS membranes were fabricated on ceramic substrates using the water-in-emulsion method and evaluated for their gas transport properties. The effects of the tetraethylorthosilicate (TEOS) concentration and curing temperature on the morphology and CO2 separation performance were investigated. The viscosity measurement showed that, at specific reaction times, it is benefit beneficial to fabricate the symmetric hybrid PDMS membranes with a uniform and dense selective layer on the substrate. Moreover, the a high TEOS concentration can decrease the reaction time and obtain create the a fully crosslinked structure, allowing more efficient CO2/N2 separation. The separation performance was furtherly improved with in the membrane prepared at a high curing temperature of 120 °C. The developed membrane shows excellent CO2/N2 separation with a CO2 permeance of 27.7 ± 1.3 GPU and a CO2/N2 selectivity of 10.3 ± 0.3. Moreover, the membrane shows a stable gas separation performance of up to 5 bar of pressure.

Effects of TEOS Precursor and Reaction Time on the Synthesis of Silica Coated Single-Walled Carbon Nanotubes

This paper demonstrates a technique to synthesize silica-coated single-walled carbon nanotubes (SWNTs@SiO2) based on sodium dodecyl sulfate (SDS), 3-aminopropyltriethoxysilane (APTES), ammonium hydroxide (NH4OH) and tetraethyl orthosilicate (TEOS). The coating of silica is done to promote bond strength between SWNTs@SiO2 and other materials. The anionic surfactant used in the coating process helps create linkages between the silica coupling agent and the SWNTs’ walls without compromising the excellent properties of SWNTs. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive x-ray spectroscopy (EDX) were employed to characterize the sizes of SiO2 particles, the structure of SWNTs@SiO2, and the elements existed in the materials. The size of SiO2 particles has shown to be dependent on the amount of TEOS concentration and reaction time. Higher TEOS concentration and longer reaction time led to larger SiO2 particles. Successful coatings of SiO2 on SWNTs have been demonstrated. Silica appeared to be uniformly coated on the SWNTs surfaces. The thickness of the coating layer was found to be approximately 3-7 nm.

Rapid growth of SiO2 nanowires on carbon fiber

We report a novel preparing route to SiO2 nanowires, which can be regarded as a modified electrochemical process, where a single C fiber is used as a substrate on which SiO2 nanowires grow, and a heating source, and tetraethyl orthosilicate (TEOS) as an electrolyte and cooling medium. The preparing process can proceed well at ambient temperature and pressure. A good quality of SiO2 nanowires can be easily obtained at 160[Formula: see text]V for only 10[Formula: see text]s, and exhibit excellent photoluminescence (PL) property. Our study also shows that reaction time, current intensity, and TEOS concentration mainly govern the formation and growth of SiO2 nanowires. The morphology, structure and composition of the as-synthesized samples were characterized by SEM, XPS, Raman, FTIR, and PL, respectively.

Intergranular insulated Fe-6.5 wt% Si/SiO2 composite compacts with tunable insulating layer thickness for low core loss applications

Variations of microstructure and eletromagnetic properities with TEOS concentration for intergranular insulated Fe-6.5 wt% Si/SiO2 composite compacts.