WUILLOUD Rodolfo German
congresos y reuniones científicas
A novel nanosilica-ionic liquid hybrid material for the selective extraction of inorganic Se(IV) from aqueous samples
LLAVER, MAURICIO; WUILLOUD, RODOLFO G.
Congreso; 5th IBEROAMERICAN MEETING ON IONIC LIQUIDS (IMIL 2017); 2017
Universidade Estadual Paulista (UNESP)
The functionalization of porous silica nanoparticles by an imidazolium-type ionic liquid (IL) (3-methyl-1-dodecylimidazolium bromide) and its application as extractant for inorganic Se(IV) from aqueous samples was studied. The hybrid material was obtained by direct contact between powdered nanosilica and an aqueous solution of the aforementioned IL in a buffered medium. The resulting functionalized material was characterized by FT-IR and UV espectroscopies, whilst the latter technique was also used to study kinetic aspects of the functionalization process, as well as the determination of sorption isotherms of IL on nanosilica. As for its application as an inorganic Se(IV) sorbent, the extraction process was quite straightforward: a known volume of an aqueous sample containing the analyte and ammonium pyrrolidine dithiocarbamate (APDC) as chelating agent were in contact with the IL-functionalized nanosilica and mixed using a vortex stirrer. Afterwards, following a centrifugation step, Se(IV) remaining in the supernatant was determined by graphite furnace-atomic absorption spectroscopy (GF-AAS) and the amount of retained analyte was calculated by difference with respect to the original concentration. Several factors affecting both the functionalization (pH, buffer concentration, contact time, amount of silica and IL) and the extraction processes (pH, sample volume, APDC/Se ratio and extraction time) were evaluated and optimized using a univariant method. Also, the selectivity of the retention process towards Se(IV) and Se(VI) species was studied. Thus, thanks to the selective chelating capacity of APDC towards Se(IV), Se(VI) was not retained on the IL-functionalized nanosilica. Retention efficiency was as high as 90% for Se(IV) under the optimal experimental conditions. Different eluents and elution methods are being studied at the moment, in order to allow the direct measurement of the retained analyte by GF-AAS. Moreover, considering the high retention achieved, the low mass of material required and the easy separation of the material after extraction; IL-functionalized nanosilica could be considered as a highly valuable nanomaterial for developing efficient preconcentration analytical methods based on solid phase microextraction (SPME) or novel remediation processes.