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Type: Artigo de periódico
Title: Crystalline Polysilicate Magadiite With Intercalated N-alkylmonoamine And Some Correlations Involving Thermochemical Data
Author: Petrucelli G.C.
Meirinho M.A.
Macedo T.R.
Airoldi C.
Abstract: Synthesized hydrated lamellar acidic crystalline magadiite (H2Si14O29·2H2O) nanocompound was used as host for intercalation of polar n-alkylmonoamine molecules of the general formula H3C(CH2)nNH2 (n = 1-6) in aqueous solution. The original interlayer distance (d) of 1500 pm, determined by X-ray powder diffraction patterns, increases after intercalation. The values correlated with the number of aliphatic amine carbon (nc) atoms: d = [(1312 ± 11) + (21 ± 2)]nc. The amount of intercalated amines (Ns), decreased as nc increased: Ns = [(5.82 ± 0.04) - (0.45 ± 0.01)]nc. The acidic layered nanocompound was calorimetrically titrated with the amines and the thermodynamic data gave exothermic values for all guest molecules, as shown by the correlation: ΔintH = -[(24.45 ± 0.49) - (1.91 ± 0.10)]nc and d = [(1576 ± 16) - (10.8 ± 1.0)]ΔintH. The negative values of the Gibbs energies and the positive entropies also presented the correlations: ΔintG = -[(22.8 ± 0.2) - (0.2 ± 0.1)]nc and ΔintS = [(6 ± 1) + (5 ± 1)]nc, respectively. © 2006 Elsevier B.V. All rights reserved.
Rights: fechado
Identifier DOI: 10.1016/j.tca.2006.06.023
Date Issue: 2006
Appears in Collections:Unicamp - Artigos e Outros Documentos

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