Silica gel ethyleneimine and its adsorption capacity for divalent Pb, Cd, and Hg

被引:23
作者
Arakaki, LNH [1 ]
Augusto, VLS [1 ]
de Sousa, KS [1 ]
Aguiar, FP [1 ]
da Fonseca, MG [1 ]
Espínola, JGP [1 ]
机构
[1] Univ Fed Paraiba, CCEN, Dept Quim, BR-58059900 Joao Pessoa, Paraiba, Brazil
关键词
silica gel; adsorption of heavy metal; thermodynamic; calorimetry;
D O I
10.1016/j.tca.2005.11.004
中图分类号
O414.1 [热力学];
学科分类号
摘要
Activated silica get was directly modified with a cyclic molecule, ethyleneimine, yielding a surface with various nitrogen basic centers, equivalent to Sil-O(CH2CH2NH)(n)CH2CH2NH2. Infrared spectroscopy, C-13 NMR, thermal, and elemental analyses confirmed the covalent attachment of the organic species onto the silica matrix. The purpose of this paper is to describe the interaction involving the grafted species on silica surface with the divalent heavy cations, Pb(II), Cd(II), and Hg(II), from aqueous solutions at room temperature, The process of metal extraction was followed by the batch method and the order of the maximum extraction capacities found was: 1.27 +/- 0.04, 1.02 +/- 0.02, and 0.98 +/- 0.01 mmol g(-1) for Pb(II), Cd(II), and Hg(II) chlorides, respectively. These interactions were followed by calorimetric titration, The enthalpies of these processes are: -3.05 +/- 0.02, -1.09 +/- 0.01, and -9.88 +/- 0.03 kJ mol(-1) for Pb(II), Cd(II), and Hg(II), respectively. The standard molar Gibbs free energies are in agreement with the spontaneity of the proposed reactions between cation and basic center. (C) 2005 Elsevier B.V. All rights reserved.
引用
收藏
页码:176 / 180
页数:5
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