Potassium iron formation, effect

Both ions can be removed by oxidation and subsequent filtration. Aeration is adequate for iron(II) oxidation at above pH 6, but the oxidation of manganese(II) is much too slow, even at higher pH values, for effective removal. Potassium permanganate or chlorine dioxide is frequently used for the oxidation of manganese however, their use must be foHowed by coagulation prior to filtration because of the formation of coHoidal Mn02. 

Xanthine oxidase, a widely used source of superoxide, has been frequently applied for the study of the effects of superoxide on DNA oxidation. Rozenberg-Arska et al. [30] have shown that xanthine oxidase plus excess iron induced chromosomal and plasmid DNA injury, which was supposedly mediated by hydroxyl radicals. Ito et al. [31] compared the inactivation of Bacillus subtilis transforming DNA by potassium superoxide and the xanthine xanthine oxidase system. It was found that xanthine oxidase but not K02 was a source of free radical mediated DNA inactivation apparently due to the conversion of superoxide to hydroxyl radicals in the presence of iron ions. Deno and Fridovich [32] also supposed that the single strand scission formation after exposure of DNA plasmid to xanthine oxidase was mediated by hydroxyl radical formation. Oxygen radicals produced by xanthine oxidase induced DNA strand breakage in promotable and nonpromotable JB6 mouse epidermal cells [33]. 

Tbe chloroxides of potassium and calcium hare the property, in common with that of sodium, of developing the tint hut chlorine does not possess it. If a little carbonate of soda is previously addsd to chlorine water, the Coloration is readily effected, in consequence of the formation of a small amount of chloroxide. Chloric, iodie, chromic, nitrous and nitric acids, and sesqui-chloride of iron, offer nothing remarkable. 

Unpromoted samples will always display deactivation under operating conditions caused by coke deposition. Alkali compounds have shown to suppress coking [12], so the effect of potassium promotion on the iron-on-titania catalysts was also investigated. The addition of potassium could induce the formation of compounds containing both iron and potassium, thus possibly preventing the iron from entering the titania lattice [3],... 

Preparation.—The metal was first isolated by Davy1 by electrolysis of the hydroxide, and shortly afterwards Gay-Lussac and Thcnard 2 obtained it by the action of iron on the carbonate. Charcoal can be substituted for iron, one process consisting in the decomposition at low red heat of potassium hydrogen tartrate,3 with formation of a mixture of charcoal and potassium carbonate, the reduction to metal being subsequently effected at a higher temperature ... 

While unpromoted Fe catalysts show mainly the formation of light alkanes in hydrocarbons, the addition of potassium to iron results in increased selectivities towards light olefins and to liquid hydrocarbons. This is in agreement with the fact that potassium has long been known as an effective promoter of iron-based catalysts for the production of olefins and long chain hydrocarbons in F-T reaction [15]. 

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