Abstract
The aim of the present work was to monitor the adsorption of thyamine hydrochloride (VB1) onto halloysite (HNT) nanoclay in different conditions (contact time, initial pH, temperature and initial concentration). The HNT-VB1 materials were also analyzed by FTIR, TGA, TEM and the release of VB1 was monitored in two different simulated body fluids. Three isotherm models were used to determine the adsorption mechanism of VB1 onto HNT. The Langmuir model showed that the adsorption process is endotherm. The Freundlich adsorption model confirms that this is a favorable process. The adsorption of VB1 onto HNT is a physical process according to Dubinin-Radushkevich isotherm. The release of VB1 from HNT takes place by Fickian diffusion and it was monitored for 24 h. The highest amount of drug released (35%) was registered in simulated gastric fluid (pH 1.2).
Keywords: halloysite nanoclay; controlled drug release; isotherm models