RESUMEN
Surface-clean Au nanoparticles (NPs) confined in films of ionic liquids (ILs) can be easily fabricated by sputtering deposition. A silicon wafer coated with films of both hydrophobic (bis((trifluoromethyl)sulfonyl)amide, NTf2-) and hydrophilic (tetrafluoroborate, BF4-) imidazolium-based ILs forms an 'ionic carpet-like' structure that can be easily decorated with Au NPs of 5.1 and 6.5 nm mean diameter, respectively. The depth profile distribution of the Au NPs depends on the arrangement of the IL, which is controlled mainly by the anion volume. Higher concentrations of Au NPs are found closer to the IL surface for the system containing a larger anion (NTf2) whereas Au NPs are located deeper in the IL for the system containing a smaller anion (BF4). The Au NPs are well distributed over the IL/Si support and are strictly confined in a single layer of the IL. This method is among the most simple and versatile for the generation of liquid layers containing surface-clean, stable and confined Au NPs.
RESUMEN
The present study has investigated the influence of the filtration step of the liquid-liquid extraction (LLE) on the quantitative analysis of di-n-butyl phthalate (DnBP) in the wastewater treatment system of the University of Caxias do Sul (WWTS-UCS). During five months, five wastewater samples from the inflow and outflow points were collected and submitted to LLE with and without the filtration step. The organic extracts were analyzed by Gas Chromatography with Flame Ionization Detection (GC/FID). The DnBP removal in the filtered samples was 36%, and the median DnBP concentration at the outflow point was 17.45 µg/mL. For the unfiltered samples, the DnBP removal was 39%, and the median DnBP concentration at the outflow point was 21.45 µg/mL. According to these results, an important fraction of the contaminant is retained in the LLE filtration step leading to considerable errors in the quantification of the target compounds.