Silica gel ethyleneimine and its adsorption capacity for divalent Pb, Cd, and Hg |
| |
Authors: | Luiza NH Arakaki Vera Lucia S Augusto Filha Kaline S de Sousa Franklin P Aguiar Maria G da Fonseca Jose GP Espínola |
| |
Institution: | Departamento de Química, CCEN, Universidade Federal da Paraíba, 58059-900 João Pessoa, PB, Brazil |
| |
Abstract: | Activated silica gel was directly modified with a cyclic molecule, ethyleneimine, yielding a surface with various nitrogen basic centers, ≡Sil–O(CH2CH2NH)nCH2CH2NH2. Infrared spectroscopy, 13C 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. |
| |
Keywords: | Silica gel Adsorption of heavy metal Thermodynamic Calorimetry |
本文献已被 ScienceDirect 等数据库收录! |
|