Supported membranes of aluminum phosphate on porous alumina substrates
0
Citation
0
Reference
20
Related Paper
Abstract:
The neat reaction of triethyl aluminum with triethyl phosphate yields a low molecular weight oil. The oligomer in an organic solvent was applied by spin coating onto porous alumina disks (Anodisc{reg_sign}, 0.02 micron filter) and calcined at 500{degrees}C to form amorphous AlPO{sub 4} membrane films. Alternatively, the films may be converted to crystalline molecular sieve films by hydrothermal treatment under pressure. The thickness and quality of the supported membranes were measured by scanning electron microscopy. The utility of the membranes for gas separations was determined by gas permeability measurements. The chemistry of the film precursor and properties of the supported membranes will be presented.Keywords:
Oligomer
Aluminium phosphate
Cite
Hydrophobic-hydrophilic composite membranes containing silicalite-1 and Al-beta zeolites are prepared on the outer surface of the porous alpha-alumina tube for the first time. The hydrophilic layer with aluminum serves as an active catalytic domain, whereas the hydrophobic layer containing silicalite-1 with medium pore-size is expected to assist in separating the reaction products based on their hydrophobicity as well as shape-selectivity. The continuous defect-free composite membranes are fabricated by two-step synthesis approach by initial deposition of Al-beta crystals on the outer surface of porous alumina tube followed by coating of silicalite-1 crystals over the Al-beta layer in the second step under hydrothermal conditions. The composite membranes exhibited a high thermal stability of up to 550 degrees C. The powder X-ray diffraction patterns of samples collected at the bottom of crystallization vessel as well as coated membranes indicated typical BEA and MFI structures consisting of ca. 0.5-0.7 nm size micropores, and free from impurity phase. The field emission scanning electron microscopic (FE SEM) analysis of the silicalite-1 sample exhibited uniform rectangular crystals of size about 20 microm; whereas Al-beta showed spherical morphology with crystal size of approximately 0.6-0.7 microm. The surface and cross-sectional analyses of composite membranes both before and after calcinations exhibited defect-free microstructures for the composite membranes. The calcined membranes exhibited single gas permeation and the observed values for composite membranes are an order of magnitude lower than that of the individual membranes.
Cite
Citations (0)
Cellulose triacetate
Cellulose acetate
Spin Coating
Dichloromethane
Cite
Citations (33)
Particle (ecology)
Gravimetric analysis
Cite
Citations (26)
Lanthanum
Carbon fibers
Tungstate
Dip-coating
Cite
Citations (13)
Diffractometer
Field emission microscopy
Ceramic membrane
Cite
Citations (11)
Porous permeable films materials have very broad prospects in the treatment of sludge-containing waste water due to their large surface area and good microfiltration. In this work, highly ordered porous membranes have been prepared successfully on ice substrates using a poly(phenylene oxide) (BPPO)-SiO2 nanoparticle (NP) mixture by the brePorous permeable films materials have very broad prospects in the treatment of sludge-containing waste water due to their large surface area and good microfiltration. In this work, highly ordered porous membranes have been prepared successfully on ice substrates using aath figure method. Based on the theory of Pickering emulsion system and capillary flow, particle assisted membrane formation was analyzed. Another two sorts of new membranes SiO2/C membrane and hierarchical porous polymer (HPP) membrane, which were obtained by modification of the BPPO-SiO2 membrane by calcination and etching, were set up in a further study. Their properties were investigated through the methods of scanning electron microscopy (SEM), fourier transform infrared spectrometry (FTIR), ultraviolet spectrum (UV), capillary electrophoresis (CE), contact angle, and water flux tests. All these results demonstrate that both surface hydrophilicity and fouling resistance of the membrane would be improved by using SiO2 as a filler. The membranes with high permeability and antifouling properties were used for microfiltration applications.
Cite
Citations (23)
Atomic layer deposition (ALD) of SiO2 onto nanoporous alumina (PA) membranes was investigated with the aim of adjusting the pore size and transport properties. PA membranes from commercial sources with a range of pore diameters (20 nm, 100 nm and 200 nm) were used and modified by atomic layer deposition using tris(tert-butoxy)silanol and water as the precursor couple. By adjusting the number of deposition cycles, the thickness of the conformal silica coating was controlled, reducing the effective pore diameter, and subsequently changing the transport properties of the PA membrane. Silica coated PA membranes with desired pore diameters from <5 nm to 100 nm were fabricated. In addition to the pore size, the transport properties and selectivity of fabricated silica coated PA membranes were controlled by chemical functionalisation using a silane with hydrophobic properties. Structural and chemical properties of modified membranes were studied by dynamic secondary ion mass spectrometry (DSIMS) and scanning electron microscopy (SEM). Spectrophotometric methods were used to evaluate the transport properties and selectivity of silica coated membranes by permeation studies of hydrophobic and hydrophilic organic molecules. The resultant silica/PA membranes with specific surface chemistry and controlled pore size are applicable for molecular separation, cell culture, bioreactors, biosensing and drug delivery.
Nanoporous
Silanol
Cite
Citations (4)
Polysulfone
Cite
Citations (24)
Study on the formation process of γ -Al 2O 3 membranes by electrophoretic deposition and their structure characteristics was performed. It is found that the γ -Al 2O 3 membranes are even and a perfect gel film can be obtained with a slow drying process. By calcinating the dried gel films, the γ -Al 2O 3 membranes well bound to the substrate are obtained. The transformation of γ -AlOOH to γ -Al 2O 3 occurs in the calcination at about 345 ℃. However, it is observed from the cross_section fracture surfaces that the thickness of the γ -Al 2O 3 membranes with nanometer pores is in the range of 17～23 μm.
Electrophoretic Deposition
Deposition
Cite
Citations (0)
Abstract Thin films of alumina were deposited onto aluminium‐treated substrates by pneumatic spray pyrolysis at 250 °C. As precursors, solutions of AlCl 3 dissolved in the mixture water:ethanol = 1:1 were used. As morphology controlling agents, maleic acid based copolymers (HFB/HFL) and/or acetylacetone were added in spraying solutions. The absorptance ( α ) and emittance ( ϵ ) values are those expected for alumina films, as possible matrix in a cermet, used as a solar‐thermal selective absorber. The films have amorphous–crystalline structure and porous morphology. The alumina film composition and crystallinity can be tailored by adding acetylacetone in the spraying solution, when predominantly amorphous structures are obtained. The addition of hydrophobic/hydrophilic copolymer in the precursor solution favours the obtaining of porous aggregates with large, open structures (3.5–4 μm). These porous morphologies are suitable for further infiltration of metallic particles, for preparation of alumina‐based cermets. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Acetylacetone
Cermet
Cite
Citations (6)