Search Results

You are looking at 61 - 70 of 1,722 items for :

  • All content x
Clear All

Abstract  

A new method for the preparation of porous silicapotassium cobalt hexacyanoferrate (SiO2 .KCoFC) composite from silica sol is described. Silica sol was first gelled with K4Fe(CN)6 solution. Then the resulting hydrogel, SiO2 .K4Fe(CN)6 was reacted with Co(NO3)2 solution in acetone to give the composite SiO2 .KCoFC hydrogel. The empirical formula of KCoFC in the composite was found to be K1.69Co 0.93Fe(CN)6. The removal efficiency of the composite for Cs was judged by measuring its distribution coefficient, K d in 1M HCl solution containing 10 ppm Cs. The K d of Cs was found to be 5.73.105 ml/g-composite.

Restricted access

paper, we propose a systematic study using platinum-based silica-supported bimetallic catalysts modified with either Sn(C 4 H 9 ) 4 (SnBu 4 ) or Ge(C 4 H 9 ) 4 (GeBu 4 ). The objective is to analyze the effect of the addition of the second metal on the

Restricted access

Abstract  

Microcrystalline zirconium phosphate (-ZrP), hydrous manganese dioxide (HMnO), ammonium molybdophosphate (AMP) and silica gel supported forms of these materials as well as silica gel (SG) itself were investigated by thermoanalytical, electron microscopic, X-ray diffraction and infrared spectrometric methods. Chemical composition, structure and some related properties of the inorganic ion exchangers mentioned above are reported.

Restricted access

Abstract  

Template syntheses of mesoporous silicas have been carried out inside large pores of inorganic matrix. Portions of tetraethoxysilane and cetyltrimethylammonium bromide micellar solution were incorporated step-by-step inside pore volume of silica gel with large pore size. Synthesized materials were characterized using thermal analysis, adsorption-desorption of nitrogen and X-ray diffraction scattering.

Restricted access

Abstract  

Spinel iron oxide (Fe3O4-γ-Fe2O3) particles were supported on microbeads of silica gel by the calcination of the silica gel base adsorbing citric acid and Fe3+ ions. The X-ray diffraction patterns and the57Fe Mössbauer spectra measured for the spinel iron oxide indicated that the particle size of the oxide was regulated by the mean pore diameter (4–82 nm) of the silica gel support employed. In the case of α-Fe2O3 particles prepared by using the same silica gel beads, it was revealed by the Mössbauer spectra and the electron micrographs that there were relatively large particles of the oxide on the surface of the beads, in addition to the particles in the silica gel micropores.

Restricted access

Mixtures of pesticides have been separated by graft thin-layer chromatography on connected layers — silica and octadecyl silica wettable with water. Separation of pesticide mixtures was achieved by two-dimensional planar chromatography using a non-aqueous mobile phase in the first dimension and an aqueous reversed-phase mobile phase in the second dimension.

Restricted access

Abstract  

High-density polyethylene, its composites with hydrophilic/hydrophobic silica and the antioxidant BHT (butylated hydroxytoluene) were studied using the thermogravimetric analysis. It has been shown that filling with silica as well as introducing BHT into the unfilled polymer increases the thermal-oxidative stability of the polymer. Immobilized BHT is inactive and it suppresses the stabilizing effect of hydrophobic silica surface in the processes of thermal oxidation at the initial stage. However, being gradually released from the surface antioxidant prolongs the resistance of the polymer against oxidation.

Restricted access

Abstract  

The effect of addition of silica on the parameters of isothermal crystallization of polypropylene has been investigated. It was found that the covering of the silica surface by a layer of low-density polyethylene leads to a deactivation of the filler regarding the positive effect on the polypropylene crystallization rate parameters. Cross-linking of the surface polyethylene layer results in a stronger attachment of the modifying polymer to the filler surface and the deactivation effect of the silica surface modification is more pronounced.

Restricted access

Abstract  

Aqueous leaching of tritium from silica gel, loaded by absorption of water vapor, makes part of reactor de-commissioning. It is found to follow the formulation of steady-state diffusion.

Restricted access

Abstract  

This article presents results of the experimental investigation on the adsorption of the water vapor on silica gel. Two independent experimental methods has been used, viz. the constant-volume-variable-pressure (CVVP) system and variable pressure thermogravimetry (TG). Results from these two methods are compared with each other. Also the isosteric heat of adsorption of this system has been determined from the equilibrium data. The silica gels investigated here are Fuji Davison type 'A' and type 'RD'. Adsorption isotherm of water vapor have been measured under a variety of conditions all referring to chiller operation cycles, i.e. temperatures from 303 to 358 K and pressures from 500 to 7000 Pa. The data collected from the two independent experiments compare very favorably with each other and their trends are consistent with those of the adsorption chiller manufacturer. This lends significant weight to our experimental data on silica gel+water systems as being valuable to the adsorption chiller manufacturers and the scientific community.

Restricted access