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|Type:||Artigo de periódico|
|Title:||Calorimetric Study Of Intercalation Of N-alkyldiamines Into α-titanium Hydrogenphosphate|
|Abstract:||A series of n-alkyldiamines of general formula H2N(CH2)nNH2 (n = 2-9) has been intercalated into the crystalline lamellar compound α-Ti(HPO4)2·H2O (TiP) from aqueous solution. The amount intercalated was followed batchwise at 298 ± 1 K and the variation of the original interlayer distance for TiP (756 pm) was followed by X-ray powder diffraction. Linear correlations with good fits were obtained for the interlamellar distance (d) or for the number of moles intercalated (nint) as a function of the number of carbon atoms in the aliphatic chain (nc): d =(883.14 ± 12.76) + (108.51 ± 2.20)nc and nint =(5.79 ± 0.12) - (0.28 ± 0.02)nc. The exothermic enthalpies for the intercalation are related to the monomolecular layer arrangement with a longitudinal axis inclined by 58° to the inorganic sheets. The enthalpies for the overall reaction 2O3P-OH(c) + H2N(CH2)nNH2(c, l) = O3P - O-+H3N(CH2)nNH3+-O - PO3(c); ΔintH, determined by reaction-solution calorimetry at 298.15 ± 0.02 K are correlated with the number of carbons in the aliphatic chain or the interlamellar distance, by the equations Δint H= -(56.16 ± 0.67)-(2.06 ± 0.12)nC and ΔintH = -(39.41 ± 1.41)-(1.80 × 10-2 ± 0.10 × 10-2)d. The enthalpic value for nc = 0 gave -56.17 ± 0.67 kJ mol-1 which corresponds to the intercalation of two moles of ammonium cation.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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