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Type: Artigo de evento
Title: 1h Nmr Spectroscopy Study Of Water Adsorbed On The Surface Of Layered Ilerite
Author: Pires C.T.G.V.M.T.
Airoldi C.
Abstract: The hydrated layered alkaline silicate ilerite synthesized by a hydrothermal methodology was characterized by various techniques that confirmed a good structural quality of the resulted material. In an attempting to investigate the characteristics of water boundary layers in this hydrated powder sorbent, 1H NMR spectroscopy method was performed to measure the temperature dependence of the observed proton signal intensities in water sorbed, from 200.15 to 298.15 K. Gibbs energy of water molecules at the sorbent water interface decreased due to the sorption interactions, causing the water dosed to the sorbent surface freezes at T < 273.15 K. Due to a disturbing action of the sorbent surface and confined space, water occurs in the quasi-liquid state. As a result, it is observed in the 1H NMR spectra narrow signal relatively, but increase in peak broadening with the decrease of temperature. The presence of two types of hydrogen bonding was observed with the presence of signals around 3.9 and 16 ppm. The water at the interface freezes when the Gibbs energies of the sorbed water ice are identical. The variation of energy of ice observed in this material was 4.37 kJ mol-1 at 200.15 K with a decrease to null value at 298.15 K. © 2013 AIP Publishing LLC.
Rights: aberto
Identifier DOI: 10.1063/1.4810605
Date Issue: 2013
Appears in Collections:Unicamp - Artigos e Outros Documentos

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