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The influence of mercury contact angle, surface tension, and retraction mechanism on the interpretation of mercury porosimetry data

The use of a semi-empirical alternative to the standard Washburn equation for the interpretation of raw mercury porosimetry data has been advocated. The alternative expression takes account of variations in both mercury contact angle and surface tension with pore size, for both advancing and retreating mercury meniscii. The semi-empirical equation presented was ultimately derived from electron mic

Structural studies on surfactant-templated silica films growtn at the air/water interface

In situ characterisation of a growing surfactant-templated silica film has been carried out by X-ray reflectivity, diffuse X-ray scattering from the surface. Brewster angle microscopy and surface pressure measurements. The results indicate an unexpected film growth mechanism where layered structures form in solution and diffuse to the interface after some critical induction period.

Humidity and temperature effects on CTAB-templated mesophase silicate films at the air-liquid interface

Off-specular X-ray reflectivity measurements were carried out to follow the in situ development of surfactant-templated silica thin films at the air-water interface under conditions of controlled relative humidity and temperature, using an enclosed sample cell designed for this purpose. The results suggest a strong dependence of formation time and growth mechanism on ambient conditions. Thin films

Microwave-electrochemical formation of colloidal zinc oxide at fluorine doped tin oxide electrodes

Colloidal ZnO is obtained during microwave-enhanced electrochemical deposition experiments from an aqueous solution containing 0.1 M Zn(NO 3)2 and 0.02 M H2O2 via repetitive negative going potential cycles from 0.3 to -0.8 V vs. SCE. The effects of temperature and temperature gradients on ZnO electro-formation at fluorine doped tin oxide (FTO) electrodes are investigated with both a conventional t

Self-assembled films formed at the air - Water interface from CTAB/SDS mixtures with water-soluble polymers

We have investigated the spontaneous self-assembly of solid, mesostructured films that form at the air-solution interface on solutions containing a neutral water-soluble polymer and catanionic surfactant mixtures of hexadecyl-trimethylammonium bromide (CTAB) and sodium dodecylsulphate (SDS). The formation processes and structures were probed using neutron reflectivity, X-ray reflectivity, off-spec

Control of mesostructure in self-assembled polymer/surfactant films by rational micelle design

Micron-thick hydrogel films with ordered 3D mesostructures form spontaneously at the interface of polyelectrolyte-surfactant solutions. Here we demonstrate that by rationally designing the micelle shapes it is possible to predict and so tailor the nanostructure formed within surfactant-polyelectrolyte films. Using quaternary ammonium surfactants with a range of packing parameters, we demonstrate t

Using nano-cast model porous media and integrated gas sorption to improve fundamental understanding and data interpretation in mercury porosimetry

The mechanisms of entrapment, and the nanoscopic spatial distribution, of the residual mercury within nano-cast and amorphous porous media (pore sizes ∼1-100 nm) following high-pressure penetration have been studied. It has been shown that, even at the nanoscale, one of the same two principle mechanisms that have been observed previously in mercury porosimetry experiments on macroscopic glass pore

Nanocasting of novel, designer-structured catalyst supports

Highly structured catalyst support pellets have been produced that possess multiple, but regiospecific and well-defined, pore geometries. Mesoporous silica pellets with controlled pore sizes have been synthesised using one type of pore template for the pellet core zone, whilst using a different type of template for the surrounding shell region. These materials offer the potential of adding precise

Chemically surface-modified carbon nanoparticle carrier for phenolic pollutants : Extraction and electrochemical determination of benzophenone-3 and triclosan

Chemically surface-modified (tosyl-functionalized) carbon nanoparticles (Emperor 2000 from Cabot Corp.) are employed for the extraction and electrochemical determination of phenolic impurities such as benzophenone-3 (2-hydroxy-4-methoxybenzophenone) or triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol). The hydrophilic carbon nanoparticles are readily suspended and separated by centrifugation prio

Growth and characterization of mesoporous silica films

The synthesis of surfactant-templated silicate materials has developed rapidly over the past decade. The uniform controlled pore sizes created in the amorphous silicate framework by this method show promise as catalyst supports, sensors, filtration membranes and in a variety of optoelectronic applications. Formation of these materials in a thin-film or membrane geometry is therefore an active area

Shear and salt effects on the structure of MCM-41 synthesis gels

Orientational ordering under shear was observed for some precursor gels for the synthesis of the hexagonal mesoporous silica MCM-41 in the presence of high KBr concentrations. The presence of KBr disrupted the formation of the first-order MCM-41 diffraction peak dependent upon KBr concentration. Synthesis gels which formed good quality MCM-41, but with no added KBr salt, were not oriented by stron

Structure and dynamics of hydrogen sorption in mesoporous MCM-41

Adsorption isotherms taken at temperatures ranging from 20 to 77 K show a large pore volume and surface area of 980 m2 g-1 for the physical adsorption of molecular hydrogen on MCM-41. The adsorbed hydrogen behaves more like a solid than a liquid and isosteric heats of adsorption reveal a heterogenous surface. The evaporation behaviour of the adsorbed hydrogen indicates that the hexagonally packed

A tale of two mechanisms : comparing mesostructure formation in cationic and non-ionic surfactant-templated silicas

The formation of surfactant templated silica films at the air-solution interface has been investigated in situ using a number of time-resolved surface-sensitive and bulk sensitive techniques. Results from templating solutions prepared using a non-ionic surfactant (C16EO8) are compared to those obtained when a cationic surfactant (CTAB) is used. In both cases specific solution phase interactions dr

Measurement of the Adsorption of Cytochrome c onto the External Surface of a Thin-Film Mesoporous Silicate by Ellipsometry

The measurement of adsorption of cytochromes c onto the external surfaces of a thin film mesoporous silicates (MPS) supported by silicon wafers was discussed. Adsorption in a multilayered system consisting silicon, SiO 2, MPS, and adsorbed proteins was analyzed using ellipsometry. Synthesis of MPS thin films on 0.5 mm thick silicon wafers was done using a dip-coating alcohol vaporization method. I

Assembly of nonionic-anionic co-surfactants to template mesoporous silica vesicles with hierarchical structures

Mesoporous silica vesicles (MSV) with a hierarchical structure were developed using triblock copolymer Pluronic P103 and anionic surfactant sodium dodecyl sulfate (SDS) as a co-surfactant in the present of an inorganic salt, sodium fluoride (NaF). To some extent, variation in the particle size and vesicle cavity diameter can be achieved by adjusting the anionic-nonionic surfactant molar ratio. An

Thin-film modified electrodes with reconstituted cellulose-PDDAC films for the accumulation and detection of triclosan

A strategy for the formation of thin reconstituted cellulose films (pure or modified)) with embedded receptors or embedded ion-selective components is reported. Cellulose nanofibril ribbons from sisal of typically 3-5 nm diameter and 250 nm length are reconstituted into thin films of typically 1.5-2.0 μm thickness (or into thicker free-standing films). Cellulose and cellulose nanocomposite films a

Effect of micelle composition on the formation of surfactant-templated polymer films

Surfactant-templated polymer films prepared from polyethylenimine (PEI), cetyltrimethylammonium bromide (CTAB), and octaethylene glycol monohexadecyl ether (C16E8) were examined and the effect of increasing the percentage of nonionic surfactant in the micelles measured using both surface and bulk-sensitive techniques. It was found that there is a strong interaction between CTAB and C16E8, although

Microcalorimetric study of ammonia chemisorption on H3PW 12O40 supported onto mesoporous synthetic carbons and SBA-15

Keggin tungstophosphoric acid supported onto mesoporous and meso-microporous materials was studied by ammonia microcalorimetry. Experiments were performed at high and low temperatures to separate the contributions of chemisorpdon and physisorption, low-temperature data being potentially important for the ambient temperature purification processes. Analysis of thermokinetic data obtained from heat