Development of Regular Hydrophobic Silica Aerogel Microspheres for Efficient Oil Adsorption

Abstract

The objective of this research was to develop new hydrophobic silica aerogel microspheres (HSAMs) with water glass and hexmethyldisilazane for oil adsorption. The effects of the hexmethyldisilazane concentration and drying method on the structure and organic liquid adsorption capacity were investigated. The hexmethyldisilazane concentration of the modification solution did not influence the microstructure and pore structure in a noteworthy manner, which depended more on the drying method. Vacuum drying led to more volume shrinkage of the silica gel microsphere (SGM) than supercritical CO 2 drying, thus resulting in a larger apparent density, lower pore volume, narrower pore size distribution, and more compact network. Owing to the large pore volume and pore size, the HSAMs synthesized via supercritical CO 2 drying had a larger organic liquid adsorption capacity. The adsorption capacities of the HSAMs with pore volumes of 4.04−6.44 cm 3 /g for colza oil, vacuum pump oil, and hexane are up to 18.3, 18.9, and 11.8 g/g, respectively, higher than for their state-of-the-art counterparts. The new sorbent preparation method is facile, cost-effective, safe, and ecofriendly, and the resulting HSAMs are exceptional in capacity, stability, and regenerability.

General Approach to the Synthesis of Metal Hybrid Carbon/Titania Aerogel for the Oxygen Reduction Reaction

“…The samples showed all black in an Ar atmosphere and slightly blue in a N 2 atmosphere. Besides, the different metal-doped samples also showed other characteristics, such as yellow products on the surface of CTA-Cr-N and metallic luster on the surface of CTA-Fe-N. 28 The XRD spectra curves are shown in panels a and b of Figure 3. Anatase TiO 2 [Powder Diffraction File (PDF) number 89-4921] and rutile TiO 2 (PDF number 71-0650) mixed crystals coexist in CTA-Fe-A, CTA-Cr-N, and CTA-Cu-N, while only the anatase phase is present in the rest of the samples.…”

“…M/RF/TiO 2 aerogels were obtained by solvent substitution and supercritical CO 2 drying (SCD). 28,31 Finally, CTA-M were produced by pyrolysis under an inert atmosphere (Ar/N 2 ). The photographs of different metal doping and atmosphere treatments are shown in Figure S1 of the Supporting Information.…”

“…The first stage occurred at 400 °C and was due to the oxidation of free carbon. 12,23,28 The second stage of weight loss occurred after 478 °C, and the rate of weight loss decreased as a result of the oxidation of titanium oxide reductants and iron-containing materials. The weight loss of the other catalysts was primarily caused by the oxidation of free carbon.…”

“…Then, the phenolic structure, metal ion, and Ti–O–Ti structure are doped with each other to form a stable metal-doped phenolic/titanium dioxide (M/RF/TiO 2 ) network. M/RF/TiO 2 aerogels were obtained by solvent substitution and supercritical CO 2 drying (SCD). , Finally, CTA-M were produced by pyrolysis under an inert atmosphere (Ar/N 2 ). The photographs of different metal doping and atmosphere treatments are shown in Figure S1 of the Supporting Information.…”

“…Aerogels have tunable composition and structure and are expected to improve the ORR catalytic performance by constructing three-dimensional networks with high porosity and specific surface area and interpores. ,− In this study, we investigate the oxygen reduction performance of TiO 2 aerogels doped with different metals, including Fe, Co, Ni, Cu, and Pt, prepared via a sol–gel and supercritical drying process. We aim to elucidate the effect of each metal dopant on the oxygen reduction performance of TiO 2 aerogels and explore the underlying mechanisms that govern their catalytic activity.…”