A superflexible hydrophobic silica-based aerogel (FHSA) was prepared via a facile sol−gel process and ambient pressure drying method. The FHSA was treated at different temperatures varying from −196 to 450 °C to evaluate its thermal and mechanical performances. The evolutions of the physical property, hydrophobicity, microstructure, pore structure, and chemical structure of the FHSA with the various treatment temperatures were investigated comprehensively. The structure of the FHSA did not show an obvious change after treatment in the liquid nitrogen. The bulk density of the FHSA increased from 0.047 to 0.077 g cm −3 when the thermal treatment temperature increased from 25 to 450 °C. The specific surface area and pore volume of the FHSA increased with the treatment temperature owing to the decomposition of the organic moieties. The Fourier transform infrared spectra showed that the methyl groups in the FHSA had excellent thermostability up to 400 °C. The water contact angles of the FHSA after treatment at

No abstract

No 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.

Macroporous titania monoliths were prepared via sol-gel method using polymer foam as templates. The polymer foam polymerized via concentrated emulsion polymerization was immerged in a solution of titanium(IV) isopropoxide in 2-propanol, which underwent a sol-gel process. The organic components were subsequently removed by calcination. The effects of various parameters, including the nature of the monomer, the volume fraction of dispersed phase of the concentrated emulsion, and concentration of the sol-gel solution were investigated. The SEM micrographs of the macroporous titania monoliths thus obtained showed that the porous structure of the final material was effectively controllable.

An efficient auto-continuous globing process was developed with a self-built apparatus to synthesize pure silica aerogel microspheres (PSAMs) using sodium silicate as a precursor and water as a solvent. A hydrophobic silica aerogel microsphere (HSAM) was obtained by methyl grafting. A reinforced silica aerogel microsphere (RSAM) was prepared by polymer cross-linking on the framework of the silica gel. The pH value of the reaction system and the temperature of the coagulating bath were critical to form perfect SAMs with a diameter of 3.0 ± 0.2 mm. The grafted methyl groups are thermally stable up to 400 °C. Polymer cross-linking increased the strength significantly, owing to the polymer coating on the framework of silica aerogel. The pore volumes of HSAM (6.44 cm3/g) and RSAM (3.17 cm3/g) were much higher than their state-of-the-art counterparts. Their specific surface areas were also at a high level. The HSAM and RSAM showed high organic sorption capacities, i.e., 17.9 g/g of pump oil, 11.8 g/g of hexane, and 22.2 mg/g of 10 mg/L methyl orange. The novel preparation method was facile, cost-effective, safe, and eco-friendly, and the resulting SAM sorbents were exceptional in capacity, dynamics, regenerability, and stability.

No abstract

No abstract