Oxidation clays

Clayden effect Clay graphite Clay oxides Clay-rubber hybrids Clays... 

Adsorption of Metal Ions and Ligands. The sohd—solution interface is of greatest importance in regulating the concentration of aquatic solutes and pollutants. Suspended inorganic and organic particles and biomass, sediments, soils, and minerals, eg, in aquifers and infiltration systems, act as adsorbents. The reactions occurring at interfaces can be described with the help of surface-chemical theories (surface complex formation) (25). The adsorption of polar substances, eg, metal cations, M, anions. A, and weak acids, HA, on hydrous oxide, clay, or organically coated surfaces may be described in terms of surface-coordination reactions ... 

Goldberg S., Forster H.S., Heick E.L. Boron adsorption mechanisms on oxides, clay minerals and soils inferred from ionic strength effects. Soil Sci Soc Am J 1993 57 704-708. 

Most of the zinc introduced into aquatic environments is sorbed onto hydrous iron and manganese oxides, clay minerals, and organic materials, and eventually is partitioned into the sediments (USEPA 1987). Zinc is present in sediments as precipitated zinc hydroxide, ferric and manganic... 

The first consideration was the speciation and distribution of the metal in the sediment and water. Benthic organisms are exposed to surface water, pore water and sediment via the epidermis and/or the alimentary tract. Common binding sites for the metals in the sediment are iron and manganese oxides, clays, silica often with a coating of organic carbon that usually accounts for ca. 2% w/w. In a reducing environment contaminant metals will be precipitated as their sulfides. There is not necessarily a direct relationship between bioavailability and bioaccumulation, as digestion affects the availability and transport of the metals in animals, in ways that differ from those in plants. 

Francombe, M.H. Rooksby, H.P. (1959) Structure transformation effected by the dehydration of diaspore, goethite and -ferric oxide. Clay Min. Bull. 4 1-14... 

R.E. Spitzer, C.R. (1977) The Viking magnetic properties experiment Primary mission results. J. Geophys. Res. 82 4547-4558 Harrison, J.B. Berkheiser,V.E. (1982) Anion interactions with freshly prepared hydrous iron oxides. Clays Clay Min. 30 97-102 Harrison, P.M. HoyT.G. (1973) Ferritin. In Eichhom, G.L. (ed.) Inorganic biochemistry. 

Kummert, R. Stumm,W. (1980) The surface complexation of organic acids on hydrous y-AI2O3. J. Colloid Interface Sd. 75 373—385 Rung, K.H. McBride, M.B. (1989) Adsorption of para-substituted benzoates on iron oxides. Soil Sd. Soc. Am. J. 53 1673-1678 Rung, K.H. McBride, M.B. (1989a) Coordination complexes of p-hydroxybenzoate on Ee-oxides. Clays Clay Min. 37 333-340 Kuntze, H. (1982) Iron clogging in soils and pipes. Analysis and treatment. DVWK Bull. 10. Parey, Hamburg, Berlin, 123 p. 

Williams, R.J.P. (1988) The influence of silicate and phosphate on the structural and magnetic properties of synthetic goethite and related oxides. Clays Clay Min. 36 165-175... 

Su, C. Suarez, D.L. (1997) In situ infrared speciation of adsorbed carbonate on aluminum and iron oxides. Clays Clay Min. 45 814-825... 

Transesterification Reactions. The heterogeneous acid-catalyzed transesterification of TGs has not been investigated as much as its counterpart, the base-catalyzed reaction. Various solids are available with sufficient acid strength to be effective catalysts for the named reaction. Among the solid acids available are functionalized polymers, such as the acid forms of some resins, as well as inorganic materials, such as zeolites, modified oxides, clays, and others. Some of these solids have already been found to be effective in transesterification reactions of simple esters and (3-ketoesters. 

Ozone applications in gas/water/solid systems cover a wide range of media such as sludges, soils, adsorbents and catalysts. Disinfection, which can be regarded as a three-phase system, is a well-described and established application (see Section A 3.2.1 and 3.3.2). The preozonation for particle removal is discussed frequently, especially in the treatment of surface water, where different organic (e. g. bacteria, viruses, algae, suspended organic matter) and inorganic (e. g. silica, aluminum and iron oxides, clay) particles can be present (see Section A 3.2.4). 

The weathering of surface rocks has had a critical role in the chemical evolution of the continental crust for most of the Earth s history. In the presence of air and water, mafic minerals tend to rapidly weather into iron (oxy)(hydr)oxides, clays, and other silicate minerals, and at least partially water-soluble salts of alkalis (sodium and potassium) and alkaline earths (calcium and magnesium). In contrast, quartz in felsic and intermediate igneous rocks is very stable in the presence of surface air and water, which explains why the mineral readily accumulates in sands and other sediments. 

Sedimentary rocks with the highest arsenic concentrations largely consist of materials that readily sorb or contain arsenic, such as organic matter, iron (oxy)(hydr)oxides, clay minerals, and sulfide compounds. Arsenian pyrite and arsenic-sorbing organic matter are especially common in coals and shales. Ironstones and iron formations are mainly composed of hematite and other iron (oxy)(hydr)oxides that readily sorb or coprecipitate arsenic. Iron compounds also occur as cements in some sandstones. Although almost any type of sedimentary rock could contain arsenic-rich minerals precipitated by subsurface fluids (Section 3.6.4), many sandstones and carbonates consist almost entirely of minerals that by themselves retain very little arsenic namely, quartz in sandstones and dolomite and calcite in limestones. 

Ukrainczyk, L. and M.B. McBride. 1992. Oxidation of phenol in acidic aqueous suspensions of manganese oxides. Clays Clay Miner. 40, 157-166. 

It is a mass transfer between a mobile, solid, or liquid phase, and the adsorption bed packed in a reactor. To carry out adsorption, a reactor, where a dynamic adsorption process will occur, is packed with an adsorbent [2], The adsorbents normally used for these applications are active carbons, zeolites and related materials, silica, mesoporous molecular sieves, alumina, titanium dioxide, magnesium oxide, clays, and pillared clays. 

The book explores various examples of these important materials, including perovskites, zeolites, mesoporous molecular sieves, silica, alumina, active carbons, carbon nanotubes, titanium dioxide, magnesium oxide, clays, pillared clays, hydrotalcites, alkali metal titanates, titanium silicates, polymers, and coordination polymers. It shows how the materials are used in adsorption, ion conduction, ion exchange, gas separation, membrane reactors, catalysts, catalysts supports, sensors, pollution abatement, detergency, animal nourishment, agriculture, and sustainable energy applications. 

Nitration and oxidation. Clay-supported Cu(N03)2, unlike clayfen (12,231), > shelf-stable for months. Like clayfen, it is a convenient source of N02+ and can leave thioacetals or selenoacetals to the carbonyl compound at 25° in high yield. It effects aromatization of 1,4-dihydropyridines in 80-92% yield. In the presence i acetic anhydride, it can effect nitration even of halobenzenes at 25° with marked, - jra-preference, which can be enhanced by use of lower temperatures. 

The literature of supported transition metal complexes has been thoroughly reviewed. In this article, the chemistry of supported complexes is covered in general terms by class of solid support these include metal oxides, clay minerals, zeolites, polymers, and ion-exchange resins. 

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