Fuming oxides

Keywords fumed oxides silica gels activated carbons carbon-mineral adsorbents toxic and narcotic compounds explosives dynamic and static adsorption... 

V. M. Gun ko, V. I. Zarko, R. Leboda, and E. Chibowski, Aqueous Suspensions of Fumed Oxides Particle Size Distribution and Zeta Potential, Adv. Colloid Interface Sci. 91(1), 1-112(2001). 

Abstract. Several series of pyrocarbon/silica adsorbents were prepared using fumed oxides of different specific surface areas, and mesoporous silica gel Si-100, as inorganic matrices. Different synthetic and natural polymers as well as glucose were used as carbon precursors. Solutions of phosphoric acid at various concentrations were utilized to prepare functionalized hybrid carbon-silica adsorbents. Nitrogen, p-nitrophenol and Cd(II) adsorption isotherms as well as AFM, XRD and XRF methods were used to estimate the structural and adsorption characteristics of the adsorbents. 

V. M. Gun ko, J. Skubiszewska-Ziqba, R. Leboda, K. N. Khomenko, O. A. Kazakova, M. O. Povazhnyak, and I. F. Mironyuk, Influence of Morphology and Composition of Fumed Oxides on Changes in Their Structural and Adsorptive Characteristics on Hydrothermal Treatment at Different Temperatures,./. Colloid Interface Sci. 269, 403-424 (2004). 

Another point concerning the suitability of fumed oxides for catalytic applications, that has to be taken into consideration, is their surface chemistry. Siloxanc (Si-O-Si) and silanol groups (Si-OH) occur at the surface of the silica particles. The former arc hydro-... 

For commercial processes, formed supports are more useful. Compared with other supports, fumed oxide supports showed new catalytic effects [41]. Some intensively investigated applications for these supports are abstracted in the following. SiC>2 pellets have been successfully introduced in a new generation of precious metal supports in vinylacetate monomer production [42]. This resulted in better selcctivities and an up to 50% higher space-time yield compared with supports based on natural alumo-silicates. In alkene hydration fumed silica pellets serve as a support for phosphoric acid. In this case, an increased catalyst lifetime and a higher space-time yield were observed [43]. Pyrogenic TiC>2 powder can be used as a starting material for the manufacture of monolithic catalysts [44] for the selective reduction of NOv with ammonia. 

Dark-brown or reddish fumes (oxides of nitrogen) acidic in reaction. 

Flammable Liquid SAFETY PROFILE Poison by intraperitoneal route. Moderately toxic by ingestion. An eye irritant. Dangerous fire ha2ard by exposure to heat, flame, sparks, or powerful oxidi2ers. Reacts violently with HNO3. Incompatible with acids, acid fumes, oxidizing materials, heat, flame, and sparks. To fight fire, use alcohol foam. When heated to decomposition it emits toxic SO. See also MERCAPTANS. 

Gunko, V.M. etal.. Surface electric and titration behaviour of fumed oxides. Colloids Surf. A, 240, 9, 2004. 

Incompatibilities and Reactivities Acids, acid fumes, oxidizers, steam... 

In addition, filling of polymer coatings with fuming oxides raises their electric conductivity, thus promoting protection of commodities from radiation and radiointerference. Formulations of the coatings described by extreme portions of the curves in Fig. 3.40 have been patented [82]. 

To lower the friction and mechanochemical wear in friction joints it is possible to use solid lubricants [71] containing fuming-oxides (FO) as an active modifier of nonferrous metals. The solid lubricants represent fine-dispersed sublimation products of lead smelting slag. 

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