RESUMEN
Four modified palygorskite powders that had been milled in mortar, in air jet mill, in Pulverisette0 vibrating ball mill and treated with hydrochloric acid were used as adsorbents for lead removal from an aqueous solution. The adsorbents were characterized by nitrogen adsorption, size measurement, mercury porosimetry and scanning electron microscopy. Inverse gas chromatography at infinite dilution and finite concentration was also implemented to determine surface properties of the four samples, in particular the irreversibility indexes, a measurement of high-energy sites. In a second part, batch adsorption experiments were carried out to study the effect of mechanical and chemical treatments on lead adsorption properties of the powder. The isotherm analysis indicated that the Langmuir model could represent the adsorption data. The sample ground in Pulverisette0 presented the highest cationic exchange capacity and led to the highest adsorption capacity despite the relatively low specific surface area and the complete destruction of the fibrous morphology of the raw powder. A correlation was shown between the cationic exchange capacity and irreversibility indexes obtained with isopropanol.
Asunto(s)
Contaminantes Ambientales/aislamiento & purificación , Plomo/aislamiento & purificación , Compuestos de Magnesio/química , Compuestos de Silicona/química , Adsorción , Cationes Bivalentes , Cromatografía de Gases/métodos , Concentración de Iones de Hidrógeno , Polvos , Soluciones , Propiedades de Superficie , AguaRESUMEN
Radiation as well as mechanical treatments induced in drugs and excipients radicals, which can be studied by electron paramagnetic resonance. A special attention is pointed about the use of electron paramagnetic resonance (EPR) to bring the proof whether or not a drug has been irradiated or not. We also discuss of other methods (thermoluminescence (TL), gas phase chromatography (GPC)) which can be used to bring the same proof in case of irradiated drugs, excipients and cosmetic products.