I am working on both materials with filtration and sedimentation processes. Does anyone have information on these two materials and the difference between them with both processes [paper, books] or any publication regarding to this work [way of mixing, pH, zeta potential, shape, permeability, wall effect, specific cake resistance, etc]?
They are quite different. Talc is a magnesium silicate http://en.wikipedia.org/wiki/Talc with layered structure, H2Mg3(SiO3)4 or Mg3Si4O10(OH)2, while calcium carbonate is a carbonate mineral CaCO3. This chemical difference is shown by differences in their hardness, sufcae charge in suspension etc.
[I] Shape:
(a) Of Ca CO3:
Triclinic.
(b) Of Talc:
Monoclinic.
[II] pH:
(a) Of CaCO3:
[i) Varying pH; with Ca(2) ion solubility as a function of CO2 partial pressure:
(ii) At p(CO2)=10^-12 and [Ca(II)]=5.19.10^-3 mol/lit] pH=12 .
And
At p(CO2)=10^-2 and [Ca(II)]=1.42.10^-3 mol/lit] pH= 7.3.
(b) Of Talc:
8.4-94.
[III] Zeta potential:
(a) Of CaCO3:
It is +40 mV at pH=9 which decreases sharply
and at pH=12.5 but is stable at -15mV
(b) Of Talc :
At pH ≈ 8 , it is – 35 mV
[IV] Permeability:
(a) Of Limestone*:
Values lie in between 8.10^-17 and 10. 10^-17 m2 at one atm.
(b) Of Talc:
Values lie in between 1.10^-19 m2 and 1. 10^-24 m2
in the pressure range 20–150 MPa.
[V] Specific Cake Resistance:
(a) Of CaCO3:
[α o ]
46.9.10^80.13
(b) Of Talc:
[α o ]
7.1.10^80.5
[VI] Wall Effect:
The consequence of a looser packing density near the walls of a rigid HPLC column. The mobile phase has a tendency to flow slightly faster near the wall because of the increased local permeability.
(a) Of CaCO3:
The aged limestone creates the look of natural stone; bringing old world charm to any room of the home. The limestone look is easily created with a faux paint technique.
(b) Of Talc:
Talc is widely known for its use in powders and as soapstone.; absorb oils, absorbs odor, serve as a lubricant and produce an astringent effect with human skin and of solids and helps the liquid paint adhere to a wall without sagging.
*Containing traces of Dolomite
Dear Mr. Banhegyi and Mr. Sehgal
Thank you very much for your information and help
Faiz
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