Phosphate exchange properties

The main interest in zirconium phosphates relates to their ion-exchange properties. If amorphous zirconium phosphate is equiUbrated with sodium hydroxide to pH 7, one hydrogen is displaced and ZrNaH(P0 2 3H20 [13933-56-7] is obtained. The spacing between the zirconium layers is increased from 0.76 to 1.18 nm, which allows this phosphate to exchange larger ions. 

We achieved, that by contact of polyurethane foam with water solution of molybdophosphate, contain by pH 1-2,5 mixture of saturated (5 NMR P=-3.20 p.p.m. apply to 85 % H PO ) and unsaturated monovacant (x=0-t-4) (5 NMR P = -0,96 p.p.m.) heteropolycomplexes Keggin staicture, equilibrium discharge in the direction produced of saturated heteropolycomplex of Dowson stmcture and on the surface of polyurethan foam formed 18-molybdo-2-phosphate acid ( P = -2,40 p.p.m. in ether extract). The formed surfaces heteropolycomplex is stable for action 1 M solution of strong acids and basics and have ion exchanged properties in static and dynamic conditions to relation to macro and micro amount of M(I) ... 

The hydrous aluminosilicates and Zr, Th, and Ti phosphates have significant ion exchange capacity (6). Further interpretive study of charge development in such systems will require recognizing the ion exchange properties and measuring trivalent cation site distribution as well as adsorption and mobility. 

Structures and Exchange Properties of Layered Metal Phosphate Hosts... 

About 40 years ago, Clearfield and coworkers started a fertile activity in the synthesis and characterization of crystalline zirconium phosphates [136,140,148], After the initial findings, an enormous research effort directed toward the syntheses and characterization and investigation of the properties of the many phases of crystalline zirconium phosphate have been carried out [140], In this regard, it has been shown that, in general, all of the zirconium phosphate phases have excellent ion-exchange properties. 

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). 

Ion-exchange properties of a novel layered titanium(IV) phosphate... 

Recent work in Versailles and Santa Barbara has led to the synthesis of several nanoporous nickel(II) phosphates. A zeolitic nickel(II) phosphate, VSB-1 (Versailles/Santa Barbara-1), was prepared under simple hydrothermal conditions [22] and has a unidimensional pore system delineated by 24 NiO and PO4 poly-hedra with a free diameter of approximately 0.9 nm (Figure 18.7). It becomes microporous on calcination in air at 350 °C, yielding BET surface areas up to 160 m g and is stable in air to approximately 500 °C. The surface area appears low compared with aluminosilicate zeolites, but the density of VSB-1 is twice that of a zeolite and the channel walls are particularly thick. VSB-1 can be prepared in both ammonium and potassium forms, and exhibits ion-exchange properties that lead, for example, to the formation of the lithium and sodium derivatives. Other cations (e.g. Mn, Fe, Co, and Zn) can be substituted for Ni in VSB-1, up to a level as high as 30 atomic%. The parent compound shows canted antiferromagnetic order at Tn = 10.5 K with 6 = —71 K on doping with Fe, Tn increases to 20 K and 6 decreases to —108 K. 

Zirconium oxalate of composition Zr0(0H)(C204H) was found to have ion exchange properties 360), although the selectivity for the alkali metals was not favorable compared to the phosphate. The oxalate is also chemically unstable in strong base and acid solutions. 

Early work on the exchange properties of amorphous zirconium phosphate has been summarized by Amphlett (29). In addition, Ahrland et al. (13,15) have studied the exchange behavior of representative fission product ions, for which they found an affinity order of UO, Ce, Y " ", Sr +, Cs+, Rb+, Na+, when amorphous gels of high P04/Zr ratios were used. The separation of certain transplutonium ions (250) on amorphous... 

Zirconium and niobium phosphates may be coprecipitated to give a product which has ion exchange properties (233). 

Different strategies to confer ion-exchange properties on bacterial cellulose were investigated. The s mthesis of a cellulose phosphate membrane was the most successful. 

The transport of lanthanum and scandium orthophosphates by phosphorus pentachloride has been examined mass spectrometrically, and zircon-type structures have been confirmed by X-ray data for LUPO4 and the corresponding arsenate. " Cerium(iv) phosphates " and phosphate sulphates have been synthesized and their ion-exchange properties investigated. 

Wide-line and n.m.r. measurements led to a value of 1.87 A for the H P distance in Zr(HP04)2 values for all other H H distances are also given. The ion-exchange behaviour of ctystalline zirconium phosphates depends on the method of preparation, and the details of the sodium-potassium exchange on this material have been investigated by two groups. The ion-exchange properties of chromium phosphates similarly... 

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