Basic cerium sulfate

Fig. 5.1.4 (A) TEM and (B) SEM of rodlike particles of basic cerium sulfate prepared by...

Hsu et al. (12) prepared rodlike basic cerium(lV) sulfate particles of 1-3 p,m in length from dilute solutions of Ce(S04)2 in acidic media at 90°C (see Fig. 5.1.4). When the concentration of SO42- is lowered, monodispersed polycrystalline spherical particles of Ce02 are obtained under similar conditions. Figure 5.1.5 shows the precipitation domains of the respective species at 90°C for 12 h. Even for the forma-... 

However, solubility, depending as it does on the rather small difference between solvation energy and lattice energy (both large quantities which themselves increase as cation size decreases) and on entropy effects, cannot be simply related to cation radius. No consistent trends are apparent in aqueous, or for that matter nonaqueous, solutions but an empirical distinction can often be made between the lighter cerium lanthanides and the heavier yttrium lanthanides. Thus oxalates, double sulfates and double nitrates of the former are rather less soluble and basic nitrates more soluble than those of the latter. The differences are by no means sharp, but classical separation procedures depended on them. 

Elemental composition Ce 42.18%, S 19.30%, O 38.53%. It is digested with nitric acid, diluted appropriately and analyzed for Ce by AA or ICP spectroscopy (see Cerium). The compound may be dissolved in small quantities of water (forms a basic salt when treated with large a volume of water). The solution is analyzed for sulfate ion by gravimetry following precipitation with barium chloride. Alternatively, the compound is dissolved in hot nitric acid and the solution analyzed for sulfate by ion-chromatography. 

On heating, all of the anhydrous sulfates of the trivalent rare-earth elements and yttrium, type formula R2(S04)3 decompose, without first melting, to basic salts (oxysulfates) of the type R203.S03, then to an oxide. The oxide final product is R203 for all the elements except cerium, praesodymium,... 

Fractional precipitation is similar to fractional crystallization technique but takes advantage of basicity differences and solubility differences. Separation of yttrium from yttrium earths by fractional precipitation is an example of differences in basicity. Separation of yttrium earths from cerium earths by double alkali sulfate precipitation in the form of double sulfates is an example of fractional precipitation. 

The cerium oxide obtained on calcination is treated with nitric acid and then hydrolysed in the presence of sulfate to give basic sulfate of 99.9% purity. The cerium-free rare earth chlorides are subjected to a solvent extraction step to produce a samarium concentrate as shown in Fig. 1.15. 

Selective hydrolysis is another way of concentrating cerium(IV). Hydrolysis to a basic nitrate or sulfate is effected by diluting and boiling a concentrated solution containing the trivalent rare-earths and cerium(lV). A high purity cerium is obtained but a complete separation cannot be achieved by this method. 

A sample of AS2O3 weighing 0.217 g is dissolved in basic solution and then acidified to make H3ASO3. Its titration with a solution of acidic cerium(IV) sulfate requires 21.47 mL. Determine the original concentration ofCe aq) in the titrating solution. 

Compounds. — In its chemical relations thorium resembles both zirconium and quadrivalent cerium. It is somewhat more markedly electropositive than either of these elements, acidic properties being entirely absent. Its neutral salts are hydrolyzed somewhat in solution, and consequently are acid to indicators. They are however sufficiently stable to permit recrystallization from water solution. In basicity thorium approaches the elements of the yttrium group. Double salts are less common than with cerium and zirconium, but characteristic double nitrates, R2 Th(N03) 6, crystallize well and are iso-morphous with the analogous ceric double nitrates. Thorium resembles cerium in forming a double potassium sulfate which is insoluble in potassium sulfate solution, hut differs from it in... 

To the double sulfate precipitate, 2 1. of water and 2 1. of 15 iV ammonia solution are added and the mixture is well stirred until the textxire of the precipitate indicates conversion to hydrous oxides (see synthesis 12D). The hydrous oxide precipitate is washed (by decantation) with large volumes of water in a 5-gal. crock until the washings, removed by siphoning, are only very slightly basic. The precipitate is then dissolved in the least amount of concentrated nitric acid. Cerium is next removed from this solution by the bromate method (see synthesis 14), and the remaining rare earths are converted to double magnesium nitrates (synthesis 15). 

Dimercury dichloride 10114-58-6 Basic brown 1 10117-38-1 Potassium sulfite 10119-53-6 Cerium stearate 10124-36-4 Cadmium sulfate 10124-37-5... 

Moeller (1973) cites the hydrolysis of Ce to a basic nitrate or sulfate selective precipitation from buffered solution (pH 3-4), after chemical or electrochemical oxidation and crystallization of (NH4)2[Ce(N03)6] from strong nitric acid solution as effective means of removing much of the cerium from crude rare earth solutions. The separations are not quantitative, however. 

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