RESUMO
Benzene, diethylbenzene, and ethylenediamine-bridged bistrialkoxy precursors were used in the synthesis of multifunctional PMO copolymers for the adsorption of phenols and metal ions. Polyoxyethylene(10) stearyl ether (Brij 76) was used as the structure director with the surfactant template approach in the synthesis. The resulting PMO copolymers with two or more bridging groups have been characterized by nitrogen gas adsorption, powder X-ray diffraction, and 13C and 29Si solid-state NMR. These organosilicas exhibit large surface areas, narrow pore size distributions, large total pore volumes, and pore ordering consistent with well ordered, hexagonally packed p6mm structures. Minimal competitive effects were observed on the adsorption of p-chlorophenol to the copolymers in the presence of copper ions in solution. Similarly, the presence of p-chlorophenol in solution or adsorbed onto the copolymers did not interfere with copper adsorption. Replacement of a small portion of the benzene bridge in the 90:10 BENZ:EDA copolymer with diethylbenzene produced a copolymer 2.5-fold more efficient for p-chlorophenol adsorption. ICP analysis revealed that greater than 98% of adsorbed copper was removed during extraction with HCl, and this extraction process can be repeated with no difference in copper adsorption after regeneration.
Assuntos
Quelantes/química , Quelantes/síntese química , Poluentes Ambientais/química , Compostos de Organossilício/química , Compostos de Organossilício/síntese química , Adsorção , Benzeno/química , Benzeno/isolamento & purificação , Clorofenóis/química , Clorofenóis/isolamento & purificação , Cristalografia por Raios X , Poluentes Ambientais/isolamento & purificação , Etilenodiaminas/química , Etilenodiaminas/isolamento & purificação , Indicadores e Reagentes , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , PorosidadeRESUMO
Arylene- and ethylene-bridged polysilsesquioxane materials have been synthesized by the hydrolysis and condensation of alkoxysilyl precursors under basic conditions. Cetyltrimethylammonium chloride was used to increase the porosity and surface areas of these materials via the surfactanttemplate approach. Structural characterization of these materials was carried out by nitrogen gas sorption and X-ray diffraction. The adsorption of three phenolic compounds (4-nitrophenol, 4-chlorophenol, 4-methylphenol) has been investigated by both batch and column testing. The arylene-bridged material exhibited a much greater affinity for all three phenols. The efficient removal of adsorbed phenols by a simple ethanol wash led to sorbent regeneration and separation of the aromatic species.
Assuntos
Fenóis/química , Siloxanas/química , Poluição da Água/prevenção & controle , Purificação da Água/métodos , Adsorção , Hidrólise , Porosidade , Poluentes Químicos da Água/análiseRESUMO
Molecular imprinting of surfaces of mesoporous sorbents is a novel method for introducing template-selective recognition sites. This method makes use of the unique surface environment of hexagonally packed mesopore surfaces of selected pore sizes (see the schematic representation) and coats such surfaces with functional ligands by binding to a metal ion template.
