The importance of diagram system MnO2─NaVO3 is in obtaining a crystal phase
(chemical compounds or solid solutions). Acknowledging the fact that these compounds
have grade properties in the field of technology, it was important to study the possibi
lity of
obtaining new phases with different mole ratios, and to draw phase diagram for it,
especially the used compounds in this study have different crystal structures.
The samples were made beginning from powders of reagent grade MnO2 and NaVO3 of
5gr for each of them at following percentage mole ratios of MnO2: (10, 20, 25, 30, 33.33,
50, 66.66, 70, 71, 75, 80, 90). The mixing and grinding process was made for these
samples. Then, it made pills ellipsoidal using manually hydraulic press, and it burned into
oven at different degrees. The study was made using powder X─Rays diffraction PXRD
and different thermal analysis TG─ DTA. The results are compared with X─rays
spectrums of grade compounds and parameters of it. Then, the formation phase changes
degrees were determined. New compound was formed at ratio (MnO2)10(NaVO3)90
mole%, and crystal solid solution was formed to ratio (MnO2)25(NaVO3)75 mole%. As well
solid solution (amorphous+ new compound) was formed until mole ratio
(MnO2)75(NaVO3)25 mole%, and amorphous solid solution was formed beginning mole
ratio (MnO2)80(NaVO3)20 mole%, then the phase diagram for the studied system was
drawing.
This study has been conducted to identify the levels of heavy
metals (lead, cadmium, nickel, cobalt, copper, iron, manganese, and
zinc) in the following spices: Nutmeg, turmeric, cinnamon, ginger,
cardamom, nigella sativa, black pepper, cumin, coriander, curry,
and mixed spices.
This study was undertaken to
evaluate the chemical speciation and distribution of Mn in soils of
Homs Governorate. Sequential extraction scheme was used to
fractionate Mn into exchangeable, bound to carbonate, bound to
manganese (Mn) and iron (Fe) oxide, organically bound, and
residual forms.
The compounds ScMnO3 and CaMnO3 were obtained by high- temperature
solid state reactions considering a stoichiometric rate of CaCO3: Mn2O3 and
Sc2O3:Mn2O3. The findings were characterized by X-ray powder diffraction.
The determination method of av
erage oxidation state of these compounds based
on dissolving the samples in concentrated HCl solution. Cl2 obtained by
dissolving the samples is reduced by KI solution. I2 was titrated with standard
sodium thiosulfate solution. In the calculation it was taken a as a fraction of
Mn3+ in the mixed oxides. The formula of Scandium manganite was formulated
as ScMnO3+0.12, and for calcium manganite as CaMnO3-0.03. The relative
standard deviation in the identification of Mn does not exceed 3,5%.
