Sulfates and Selenates

H3Pa0(S04)3 and H3Pa0(Se04)3 are isostructural, possessing hexagonal symmetry (Table XIV). Full structural details are not available, but infrared studies have indicated the presence of bidentate sulfate and selenate groups. 

Cbystallogbaphic Data fob Some Miscellaneous Protactinium Compounds 

Although it is known that protactinium(V) precipitates from dilute sulfuric acid on the addition of potassium sulfate, the product, believed to be K3Pa0(S04)3, has not been satisfactorily characterized [19, 28, 105). There is obviously scope for further research on the preparation of sulfato (and selenato) complexes of pentavalent protactinium. In addition, tetravalent protactinium sulfates, selenates, and their complexes have not been studied. 

The remaining compounds of protactinium are more conveniently dealt with together since they belong to several different classes. 

Protactinium metal reacts with hydrogen to form the black hydride, PaHs, which is isostructural with other actinide trihydrides it has only been prepared in submilligram amounts and identified by X-ray powder diffraction analysis [125). 

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Wu CH, Shang LL, Cheng FL, Chao YK (2001) Modeling competitive adsorption of molybdate, sulfate and selenate on y-Al203 by the triple-layer model. J Colloid Interf Sci 233 259-264... 

Aqueous 1 M chromium trioxide (12) does not react with metallic polonium, but with polonium(IV) hydroxide or tetrachloride yields an orange-yellow solid, thought to be Po(Cr04)2. This is insoluble in an excess of the reagent and is easily hydrolyzed by water or wet acetone to a dark brown basic chromate with a composition close to 2Po02 Cr()3 (cf., the basic sulfate and selenate). On long standing in an excess of aqueous chromium trioxide, oxidation to polonium(VI) may occur (Section VI,A). 

There are few reports on nickel(II) coordinated to sulfate and selenate species.1688... 

Phosphate, silicate, borate, arsenate, selenite, chromate, and fluoride are anions for which ligand exchange is important. Nitrate, chloride, bromide, and perchlorate are not held, while sulfate and selenate may be weakly held. As a consequence, leaching of nitrate and sulfate from soil in drainage water can be significant, but very little phosphate is lost in solution. Of the trace metals, Co, Cu, Ni, and Pb are strongly held on oxide surfaces by chemisorption, but the process is much less important for Cd and Zn. 

Wijnja H. and Schulthess C. P. (2000) Interaction of carbonate and organic anions with sulfate and selenate adsorption on an aluminum oxide. Soil Sci. Soc. Am. J. 64, 898—908. 

When crystals are noncentrosymmetric, the situation becomes more complicated because there are two possible phases angles that are derived for each reflection for data from one isomorphous pair. Therefore, in order to derive the phase angle, more than one isomorphous pair is required. This problem was first tackled by Johannes M. Bijvoet, Cornells Bokhoven and Jean C. Schoone, who solved the noncentrosymmetric isomorphous structures of strychnine sulfate and selenate. ... 

Bokhoven, C., Schoone, J. C., and Bijvoet, J. M. On the crystal structure of strychnine sulfate and selenate. III. [001] projection. Proc. Koninklijke Nederlandse Akademie van Wetenschappen [Proc. Roy. Acad. (Amsterdam)] 52, 120-121 (1949). 

The presence of sulfate and selenate VI does not affect the uptake of phosphate,... 

Wu. Ch.H. et al.. Modeling competitive adsorption of molybdate, sulfate, and selenate on y-ALO, hy the triple-layer model, J. Colloid Interf. Sci., 233, 259, 2001. Hachiya. K. et al.. Static and kinetic studies of adsorption-desorption of metal ions on y-ALO, siuface. 1. Static study of adsorption-desoiption, J. Pltys. Chem., 88, 23, 1984. Tamiu a, H.. Katayama. N., and Furuichi, R.. Modeling of ion-exchange reactions on metal oxides with the Frumkin isotherm. 1. Acid-base and charge characteristics of MnO,. TiO,. Fe,O4. and ALO, surfaces and adsorption affinity of alkali metal ions. Environ. Sci. Technol.. 30. 1198. 1996. 

HYDROGEN BONDING SYSTEMS IN ACID METAL SULFATES AND SELENATES... 

This work deals with general structural aspects of crystalline metal hydrogen sulfates and selenates with special emphasis on the hydrogen bonding systems in these... 

Table 1. Compositions of Structurally Characterized Hydrogen Sulfates and Selenates of Mono- and Divalent Metals...

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