Calcium titanate/magnesium titanate/carbon-based nanocomposite
A porous particulate nanocomposite material comprising, as determined by X-ray diffraction: carbon; an orthorhombic CaTiO 3 crystalline phase; and, a rhombohedral MgTiO 3 crystalline phase. Based on the total number of atoms in the nanocomposite material and as determined by energy dispersive X-ray spectroscopy (EDX): the atomic concentration of carbon (C) is from about 1 to about 5 atom % (at. %); the atomic concentration of titanium (Ti) is from about 20 to about 35 at. %; the atomic concentration of magnesium (Mg) is from about 5 to about 15 at. %; and, the atomic concentration of calcium (Ca) is from about 5 to about 15 at. %.
1. A porous particulate nanocomposite material comprising, as determined by X-ray diffraction:
carbon;
an orthorhombic calcium titanate (CaTiO 3 ) crystalline phase; and,
a rhombohedral magnesium titanate (MgTiO 3 ) crystalline phase,
wherein, based on the total number of atoms in the nanocomposite material and as determined by energy dispersive X-ray spectroscopy (EDX):
the atomic concentration of carbon (C) is from about 1 to about 5 atom % (at. %);
the atomic concentration of titanium (Ti) is from about 20 to about 35 at. %;
the atomic concentration of magnesium (Mg) is from about 5 to about 15 at. %; and,
the atomic concentration of calcium (Ca) is from about 5 to about 15 at. %.
2. The porous particulate nanocomposite material according to claim 1 , wherein based on the total number of atoms in the nanocomposite material:
the atomic concentration of C is from about 2 to about 4 at. %;
the atomic concentration of Ti is from about 25 to about 30 at. %;
the atomic concentration of Mg is from about 5 to about 10 at. %; and,
the atomic concentration of Ca is from about 5 to about 10 at. %.
3. The porous particulate nanocomposite material according to claim 1 having a volume average crystallite size, as determined by X-ray diffraction, of from about 50 to about 55 nanometer (nm).
4. The porous particulate nanocomposite material according to claim 1 having a volume average crystallite size, as determined by X-ray diffraction, of from about 52 to about 54 nm.
5. The porous particulate nanocomposite material according to claim 1 having a heterogeneous morphology comprising substantially spherical particles, flake-like particles and agglomerates thereof.
6. The porous particulate nanocomposite material according to claim 1 having a heterogeneous pore size distribution.
7. The porous particulate nanocomposite material according to claim 1 , wherein the material comprises, as determined by scanning electron microscopy (SEM):
a first fraction of pores having a diameter greater than about 2 micrometer (μm); and,
a second fraction of pores having a diameter less than about 1 μm.
8. A method for preparing the porous particulate nanocomposite material as defined in claim 1 , the method comprising:
forming a mixture by adding an aqueous solution of a calcium salt and a magnesium salt to a solution in a polar protic solvent of a titanium compound selected from the group consisting of titanium methoxide (Ti(OMe) 4 ), titanium ethoxide (Ti(OEt) 4 ), titanium isopropoxide (Ti(OiPr) 4 ), titanium tert-butoxide (Ti(O-tBu) 4 ) and titanium diisopropoxide bis-acetylacetonate;
adding an aqueous solution of a polyol into the mixture to form a gel;
heating the gel under stirring at a temperature of from about 100 to about 200° C. for a sufficient duration to form a dry powder; and,
calcining the dry powder at a temperature of from about 600 to about 800° C. to form the nanocomposite material.
9. The method according to claim 8 , wherein the aqueous solution of the magnesium salt and the calcium salt is added in a dropwise manner into the solution of the titanium compound in the polar protic solvent.
10. The method according to claim 8 , wherein:
the magnesium salt is selected from the group consisting of magnesium sulfate (MgSO 4 ), magnesium nitrate (Mg(NO 3 ) 2 ), magnesium chloride (MgCl 2 ) and magnesium acetate (Mg(CH 3 COO) 2 ); and,
the calcium salt is selected from the group consisting of calcium sulfate (CaSO 4 ), calcium nitrate (Ca(NO 3 ) 2 ), calcium chloride (CaCl 2 ) and calcium acetate (Ca(CH 3 COO) 2 ).
11. The method according to claim 8 , wherein:
the magnesium salt is magnesium nitrate (Mg(NO 3 ) 2 ); and,
the calcium salt is calcium nitrate (Ca(NO 3 ) 2 ).
12. The method according to claim 8 , wherein the titanium compound is titanium tert-butoxide (Ti(OtBu) 4 ).
13. The method according to claim 8 , wherein the polar protic solvent is selected from the group consisting of: methanol; ethanol; n-propanol; t-butanol; acetic acid; and, mixtures thereof.
14. The method according to claim 8 , wherein the polar protic solvent comprises ethanol and/or acetic acid.
15. The method according to claim 8 , wherein the aqueous solution of the polyol is added in a dropwise manner into the mixture.
16. The method according to claim 8 , wherein the polyol is selected from the group consisting of: sorbitol; maltitol; erythritol; xylitol; mannitol; inositol; lactitol; α-glucopyranosyl-1,6-mannitol; α-glucopyranosyl-1,6-sorbitol; cellobitol; maltotriitol; and, maltotetraitol.
17. The method according to claim 8 , wherein the polyol is mannitol.
18. The method according to claim 8 , wherein the dry powder is calcined at a temperature of from about 600 to about 800° C. for a duration of from about 2 to about 6 hours to form the porous particulate nanocomposite material.
19. A method of immobilizing inorganic pollutants disposed in an aqueous medium, the method comprising contacting the aqueous medium with the porous particulate nanocomposite material as defined in claim 1 .
20. A method of degrading organic pollutants disposed in an aqueous medium, the method comprising contacting the aqueous medium with the porous particulate nanocomposite material as defined in claim 1 while irradiating the aqueous medium with actinic irradiation.