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Type: Artigo
Title: Mercaptopropyl-grafted Magadiite For Lead And Cadmium Sorption And Calorimetric Determination
Author: Pires
Cleo T. G. V. M. T.; Pinto
Alane A.; Sousa
Kaline S.; Airoldi
Abstract: Sodium magadiite anchored with 3-mercaptopropyltrimethoxysilane was synthesized through direct functionalization. After this reaction, it was observed a decrease in crystallinity, with a slight increase in basal distance to 1.57 nm, when compared to the precursor value of 1.53 nm. This organofunctionalization was evidenced through infrared spectroscopy, indicating by the presence of C-H stretching vibration in the 2900-2800 cm(-1) region and mainly from the appearance of T species at the Si-29 NMR spectrum, centered at -65 and -55 ppm. The pendant chains covalently bonded to magadiite layers have the ability to sorb lead and cadmium cations, through a batch-wise method at 298 +/- 1 K, to give the maximum sorption capacity values of 1.54 and 2.72 mmol g(-1), respectively. The energetic effects caused by both cation/sulfur basic center interactions at the solid/liquid interface were determined through calorimetric titration, to give the enthalpies -13.48 +/- 0.05 and -0.83 +/- 0.053 kJ mol(-1) for lead and cadmium, respectively. The sulfur basic centers attached to the pendant chains reflect in spontaneous process with negative Gibbs energies of -26.8 +/- 0.1 and -24.5 +/- 0.1 kJ mol(-1), resulting also in positive entropies of 44 +/- 1 and 79 +/- 1 J K-1 mol(-1), respectively. This set of favorable thermodynamic data is more pronounced for the softer cation in interacting with the basic atom.
Subject: Magadiite
Editor: Springer
Citation: Journal Of Thermal Analysis And Calorimetry. Springer, v. 126, p. 1513 - 1520, 2016.
Rights: fechado
Identifier DOI: 10.1007/s10973-016-5684-3
Date Issue: 2016
Appears in Collections:Unicamp - Artigos e Outros Documentos

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