Fabrication of boehmite and Al2O3 nonwovens from boehmite nanofibres and their potential as the sorbent

Abstract

Boehmite nonwovens with hierarchical texture could be fabricated by a simple procedure consisting of mixing a boehmite nanofibre sol with an organic solvent and filtering the mixture. However, whether the nonwovens were obtained or not depended on the solvents. High polar solvents such as methanol and ethanol caused gelation of the mixture, and low polar solvents such as toluene and ether yielded condensates in the mixture. The medium polar solvents with solubility parameters of 9-12.5, concretely, mixtures of butanol with methanol, ethanol and isopropanol, were favourable for obtaining the nonwovens. The nonwovens consisted of bundles of boehmite nanofibres, and the texture, pore volume, bulk density and porosity of the nonwovens roughly depended on the thickness of the bundles. Thus, thinner bundles and thicker bundles gave dense and loose textures, respectively. The bundles became thicker by increasing the butanol content in the mixed alcohols, and thinner by increasing the methanol, ethanol and isopropanol content. The nonwovens could be transformed from boehmite to q-Al 2 O 3 via g-Al 2 O 3 in the crystal phase while maintaining seemingly the original texture when the calcination temperature was raised to 1000 C stepwise. The nonwovens were tested as sorbents for polycyclic organics such as chromaqurol B, stilbazo and alizarin yellow R in water, and it was found that the nonwovens absorb chromaqurol B and stilbazo effectively, but alizarin yellow R slightly.

Electrospun flexible self-standing γ-alumina fibrous membranes and their potential as high-efficiency fine particulate filtration media

“…[25][26][27][28] Recently, alumina brous membranes have been fabricated by self-assembly of alumina nanobers 29 or ltering a mixture of boehmite nano-ber sol and organic solvent. 30 The alumina bers that these membranes are composed of were nanobers with diameters of 2-10 nm and lengths of 200-6000 nm, which are conducive to their application as adsorbents but their exibility and mechanical properties are adverse to this. Therefore, the membranes are being used as sorbents, but are not suitable for self-standing ltration media.…”

A mechanically adaptive hydrogel with a reconfigurable network consisting entirely of inorganic nanosheets and water

“…For the creation of inorganic-based biomimetic soft materials, the most promising constituents are inorganic nanomaterials such as nanoparticles, nanofibers, or nanosheets 17 . When these inorganic materials self-assemble to form 3D architectures in water, they sometimes afford hydrogels [18][19][20][21][22][23][24][25] . In most cases, the inorganic nanomaterials aggregate through attractive interactions, such as van der Waals attraction or electrostatic attraction, to form interconnected 3D networks that can hold large quantities of water; these materials are referred to as attraction-dominant gels ( Fig.…”

“…In most cases, the inorganic nanomaterials aggregate through attractive interactions, such as van der Waals attraction or electrostatic attraction, to form interconnected 3D networks that can hold large quantities of water; these materials are referred to as attraction-dominant gels ( Fig. 1e-g) [18][19][20][21][22] . However, inorganic nanomaterials can also participate in another type of self-assembly to produce a 3D architecture that is capable of exhibiting a gel-like behavior, although previous examples are limited to only a few examples on charged inorganic nanosheets [23][24][25] .…”

Alumina nanofibrous structural self-organization in hollow nanotubes caused by hydrogen treatment

“…Nanofibers can self organize in solutions. It was described [11] reorganization, i.e., the packing of oxide nanofibers under the influence of solvent. It was shown that freshly prepared sol gel fibers of γ alumina with thicknesses of 1-7 nm immersed into mixtures of different polar liquid sol vents are ordered in space and packed into bunches of fibers with thicknesses of about 30 nm, while the fibers themselves keep a constant thickness.…”