Manganese selenites

No phase diagram of the system MnSe03-H20-Se02 has been found. 

Since the calculation of the formation values and entropy from the experiments involved non-TDB auxiliary data, they are included in Appendix E. 

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The primary solubility data and the calculation of the solubility products, defined in the usual way, are presented. This presentation contains some unexpected results. The total solubility of the metal ion and selenite are approximately equal in water and in the inert salt solutions for the magnesium and manganese selenites. This is the expected result for a simple dissolution reaction. For calcium selenite, the metal ion concentration was about 100 times greater than the total selenite concentration whereas for zinc selenite the opposite was found. There is no comment in the paper on these results, which contradict the equilibrium reactions used in the paper to define the reported solubility products for calcium and zinc selenite. The review also noted that the calculation of the magnesium and selenite activities from the total concentrations introduces activity coefficients between 0.1 to 0.01 at moderate ionic strengths. Thus the values of these coefficients appear unreasonably small. On the whole, the activity coefficient corrections introduced appear to vary in an erratic way between the various systems studied. 

Alkaline-Earth Sulfides and Sulfoselenides. Activated alkaline-earth sulfides have been known for a long time their luminesence is very varied. Emission bands between the ultraviolet and near infrared can be obtained by varying the activation. They are produced by precipitation of sulfates or selenites from purified solutions, followed by reduction with Ar-H2. The addition of activators, for example, copper nitrate, manganese sulfate, or bismuth nitrate, is followed by firing for 1 - 2 h. Alkaline-earth halides or alkali-metal sulfates are sometimes added as fluxes. 

As would be expected from this affinity sequence, phosphate out-competed Mo for surface sites in multisorbate systems. The work of Balistrieri and Chao (1990) indicated that at pH 7, phosphate has greater affinity for amorphous Fe oxide than does molybdate, whereas the reverse is true for the affinity sequence on manganese dioxide. This difference also was reflected in the abilities of phosphate and molybdate to compete with selenite at pH 7 on the two oxides. 

Zinc has been quantitatively coprecipitated with Fe(OH)3 from solution 23-28), from river water (26, 27), and from 200 liters of seawater (28). Suzuki and Ozaki (25) used Fe(II) and Fe(III) to produce a precipitate whose filtration was facilitated by a magnetic field. Many other metals have been coprecipitated with iron(III) hydroxide, including the following lead(II) (25, 27) mercury(II) (25, 26, 29) chromium (25, 30) cadmium (25, 26) manganese(II) and or-ganomanganese (28) thallium (57) silver (52) selenium as selenite (25, 55) arsenic(III) and (V) (25, 34-39) antimony(III) (37-39) zinc(II) and or-ganozinc (28). The combination of coprecipitation with sensitive analytical techniques allows the determination of the metal content of water at the ppb and... 

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