How do I separate ions of transition metals: nickel, cobalt and manganese by precipitation (hydroxide and carbonate) from the leaching solution?
Please check the "Qualitative Analysis Using Selective Precipitation" procedures in general or analytical chemistry books. According to these methods, the cations you have mentioned are separated from solution as sulfide. One has to know what other metals are there in this leaching solution. To precipitate these ions as sulfides, a solution of slightly alkaline of thioacetamide (CH3CSNH2) is used.
Hi Prof.Pavel Pazdera
Thanks for your answer, but Precipitation pH of nickel, cobalt and manganese with sodium sulfide how much should be?
If you add sodium sulfide there is no need for adjusting the pH of the solution. The concentration of the sulfide ions is high enough.
Dear Manohar Sehgal, thank you for informative and instructive answer. Can i use soda and sodium sulphide instead of carbon dioxide and hydrogen sulphide respectively ? If not , plz ,say me using guidelines of carbon dioxide and hydrogen sulphide ? thanks
Hi,prof.Manohar Sehgal. in order to preparation of TGA analysis samples of carbonate or hydroxide of cobalt , in what temperature and how long it should be dried. Thanks
These 5 observations are noted from the experience while doing TGA of inorganic compounds:
[1] Start from room temperature,i.e. about 20 C or 20+C after drying the compound( keeping in a drying box for about 3/ 4 hrs )
[ 2] For Ni(OH)2 must go up to 600C or a liitle more
[3] For Mn(OH)2 which can also contain MnO2.H2O, you should go up to higher than 600C because the formation of higher oxidation states of the oxide like alpha Mn2O3 and even Mn3O4 is also a possibility.
[4] For CoCO3 continue up to 900C.
Pls read below the reference:
Journal of thermal analysis
June 1996, Volume 46, Issue 6, pp 1801-1808
The results obtained revealed that basic cobalt carbonate decomposed at 335C to produce Co3O4which remained stable up to 850C and then decomposed above this temperature giving CoO which transformed into Co3O4 on cooling to room temperature.
[5] In general:
Most hydroxide materials considered here yield oxides on thermal decomposition above 500 C.
Hi,prof.Manohar Sehgal, so much thanks for your experiences that you put on my hands.
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