Search results for "Silica aerogel"
showing 4 items of 4 documents
Temperature effects on the IR absorption bands of hydroxyl and deuteroxyl groups in silica glass
2009
Abstract In this report we will show the changes of the band shape of the hydroxyl group (SiOH) infrared (IR) absorption band (∼3670 cm −1 ) in silica glass induced by lowering temperature in the range from 290 to 20 K. This band is considered as the overlap of several spectral components associated to the vibrational activity of hydroxyl groups in different bond configurations. By a suitable analysis of the experimental band profile in terms of different sub-bands, we studied the thermal evolution of each component and we reconsidered their assignations. For comparison we examined the SiOD absorption band (∼2710 cm −1 ) as a function of temperature as well. Our data can be interpreted as a…
Supercritical Fluid Adsorption of Domperidone on Silica Aerogel
2013
Silica aerogel (SA) was loaded with domperidone to demonstrate the potentiality of adsorption processes based on the usage of supercritical carbon dioxide to treat poorly water-soluble drugs, forming new kinds of drug delivery systems. The effects of pressure, temperature and solution concentration on loaded SA were studied. Adsorption isotherms were measured at 35℃ and 45℃ and fitted with Langmuir model. Release kinetics of the adsorbed drug were also evaluated by in vitro dissolution tests. Results showed that domperidone can be uniformly dispersed into the aerogel and that the release rate of domperidone from the composite, constituted by drug and silica aerogel, is much faster than that…
Nimesulide adsorbed on silica aerogel using supercritical carbon dioxide
2012
Silica aerogel (SA) was loaded with nimesulide, a drug model compound, to demonstrate the potentiality of adsorption processes based on the usage of supercritical carbon dioxide to treat poorly water-soluble drugs, forming new kinds of drug delivery systems. Adsorption isotherms and kinetics were measured and described by models. The effect of pressure, temperature and solution concentration on loaded SA were also studied. Modelling of kinetic data showed that the sorption process was best described by a pseudo-second-order model. The adsorption isotherm data were best fitted by the Freundlich isotherm. The drug/SA composites were characterized using scanning electron microscopy, X-ray micr…
Eumelanin Coating of Silica Aerogel by Supercritical Carbon Dioxide Deposition of a 5,6-Dihydroxyindole Thin Film
2018
Eumelanin integration in silica aerogel (SA) was achieved via supercritical adsorption of 5,6-dyhydroxyindole (DHI) from CO2. Notably, after the supercritical treatment, DHI evolved towards spontaneous polymerization, which resulted in uniform pigment development over the SA. The new material was characterized for its morphological and physicochemical properties, disclosing the formation of a eumelanin-like coating, as confirmed by UV&ndash