Anion exchange properties

Unloaded silica does not recover HPA from aqueous solution. The surface of silica gel modified with quarternary ammonium salts (QAS) gets anion-exchange properties. The aim of the work is the elaboration of solid-phase reagents on the base of ion associate of HPA with QAS immobilized onto silica surface for the determination of phosphoms and organic reductants. Heterocyclic (safranine and lucigenine) and aliphatic (trinonyloctadecyl ammonium iodide and tetradecyl ammonium nitrate) compounds have been examined as QAS. 

Hydrated alumina is one of the most widespread hydrophilic polar sorbents for concentration and separation of different substances. In water Al Oj shows cation or anion exchange properties and its protolytic and adsorption characteristics depend on a way of obtaining. 

Layered double hydroxides (LDH), also referred to as anionic clays, are very useful materials due to their anion exchange properties. LDH display a layered structure built on a stacking of positive layers ([MII1 MIII (OH)2] +), separated by inter-lamellar domains constituted of anions and water molecules ([X e nH20]x ) [117]. 

Elless, M.P. Rabenhorst, M.C. (1994) Hematite in the shales of the Triassic Culpeper Basin of Maryland. Soil Sci. 158 150-154 Ellis,)., Giovanoli, R. Stumm,W. (1976) Anion exchange properties of -FeOOH. Chrmia 30 194-197... 

Researchers found that zeolite particles can be treated with high-molecular-weight surfactants [such as hexadecyltrimethylammonium (HDTMA)]. HDTMA does not penetrate into the internal pore structure of the zeolite, but coats the outer surface. The outer surface then develops hydrophobic anionic exchange properties, while the inner surface retains the capacity to adsorb cations. Researchers claim that SMZ can be used for the three major classes of water contaminants inorganic cations, inorganic anions, and nonpolar organics. 

It is interesting that, when organic and inorganic tripolyphosphates were employed under the same conditions, only 0.2-0.6 % of the phosphate donor was utilized (Lowenstein, 1958, 1960 Tetas and Lowenstein, 1963 Le Port et al., 1971). Our experimental findings thus lead to the conclusion that, as the Earth cooled and a hydrosphere was formed on its surface, a variety of transphosphorylation reactions became possible in the primeval ocean, in particular, the phosphorylation of Pi by PolyP to give pyrophosphate. It should be noted that the non-enzymatic synthesis of PolyP and pyrophosphate on the primitive Earth could take place not only in solutions, but also on the surface of some minerals with anion-exchange properties (Arrhenius et al., 1993,1997). 

Miyata, S. (1983). Anion-exchange properties of hydrotalcite-like compounds. 

A high-capacity, weak-base anion-exchange resin has been prepared by suspension polymerization of methacrylic acid with DVB followed by the amination of the beads with an alkylamine. The resin has good anion-exchange properties and dimentional stability, and can be used in deionization of water as a substitute for silica... 

The ion-exchange tests with organic anion salts did not verity any anion-exchange properties of the samples under study. The presence of organic anions has not been detected by IR in the treated samples. The introduction of tin results in cation-exchange properties. The cation capacity of the sample SnAlPO-0.05 was about 0.13 Cu2" /u.c. and 0.08 Co /u.c.. The respective values for sample SnAlPO-0.1 were 0.19 and 0.14. The molar contribution of Sn in unit cell of the above SnAlPO samples is 0.1 and 0.24, respectively. Thus the number of the cations introduced correlates with the tin number. The presence of cation-exchange properties proves localization of tin in the framework positions. 

The highly cross-linked polymeric nonporous core may consist of either a polystyrene-divinylbenzene or an ethylvinylbenzene-divinylbenzene substrate. The latex coatings are generally made from vinylben-zenylchloride polymer cross linked with divinylbenzene and fully functionalized with an appropriate quaternary amine for introducing anion-exchange properties. 

This type of polymer is used, for example, to make resins with strong anion exchange properties[5]. Because the amino groups directly connected to the aromatic ring are weak bases, further methylation can be applied to form quaternary amines that are stronger bases. Pyrolysis of this type of polymer gives indication of both type of condensation. 

The anions of adsorbed mineral acids are loosely bound at the surface and form a diffuse cloud of counter ions around the surface of the carbon particles. When the second oxygen chemisorption occun on immersion in pure water, the bound counter ions are OH ions. Obviously, the counter ions can be exchanged for other negatively charged ions, the carbons have anion exchange properties. 

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