Modification of aminopropyl silica gel with some chelating agents and their effect on its stability against hydrolysis |
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Authors: | Khaled S Abou-El-Sherbini |
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Institution: | (1) Department of Inorganic Chemistry, National Research Centre, 31 Elbohoos st., Dokki, Giza, Egypt;(2) Faculty of Science and Arts of Sharurah, Najran University, Sharurah, Saudi Arabia |
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Abstract: | The stability of aminopropyl-silica gel (AP-SG) against hydrolysis was investigated after modification by 2,3-butanedione
monoxime (BDMO), 8-hydroxyquinoline-2-carboxaldehyde (HQC) or isatin (Is) by Schiff’s base condensation reaction. The hybrid
modified silica gel (HMSG) compounds; BDMO-SG, HQC-SG and Is-SG were characterized by IR, thermogravimetric and elemental
analyses, magic angle spinning-13C-nuclear magnetic resonance, pH-metric titration and inductively coupled plasma–optical emission spectrometry-monitored silica
hydrolysis. The stability of the HMSG’s was found to be dependant on the type of the functionalization group, which may protect
the silica surface via; (1) the delocalization of the free lone pair of electrons on nitrogen of the propylamine group in
the aromatic rings, which reduces local basicity experienced on the silica surface, (2) the hydrophobic nature of the organic
substrates, which hinders the attack of hydroxide ions and water molecules, and (3) the bulky organic substrate, which hinders
nucleophilic attack on silicon. HQC-SG is recommended as an optimal modification to meet the requirements of stability, capacity
and separation efficiency of Hg(II) at pH 4.1. |
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Keywords: | Silica gel Functionalization Hydrolysis Separation Mercury |
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