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- Designing silica xerogels containing RTIL for CO2 capture and CO2/CH4 separation: Influence of ILs anion, cation and cation side alkyl chain length and ramificationPublication . Dos Santos, Leonardo; Bernard, Franciele L.; Polesso, Barbara B.; Pinto, Ingrid S.; Frankenberg, Claudio C.; Corvo, Marta C.; Almeida, Pedro L.; Cabrita, Eurico J; Einloft, SandraCO2 separation from natural gas is considered to be a crucial strategy to mitigate global warming problems, meet product specification, pipeline specs and other application specific requirements. Silica xerogels (SX) are considered to be potential materials for CO2 capture due to their high specific surface area. Thus, a series of silica xerogels functionalized with imidazolium, phosphonium, ammonium and pyridinium-based room-temperature ionic liquids (RTILs) were synthesized. The synthesized silica xerogels were characterized by NMR, helium pycnometry, DTA-TG, BET, SEM and TEM. CO2 sorption, reusability and CO2/CH4 selectivity were assessed by the pressure-decay technique. Silica xerogels containing IL demonstrated advantages compared to RTILs used as separation solvents in CO2 capture processes including higher CO2 sorption capacity and faster sorption/desorption. Using fluorinated anion for functionalization of silica xerogels leads to a higher affinity for CO2 over CH4. The best performance was obtained by SX- [bmim] [TF2N] (223.4 mg CO2/g mg/g at 298.15 K and 20 bar). Moreover, SX- [bmim] [TF2N] showed higher CO2 sorption capacity as compared to other reported sorbents. CO2 sorption and CO2/CH4 selectivity results were submitted to an analysis of variance and the means compared using Tukey's test (5%).
- Waterborne polyurethane/Fe3O4-synthetic talc composites: synthesis, characterization, and magnetic propertiesPublication . Dos Santos, Leonardo; Ligabue, Rosane; Dumas, Angela; Le Roux, Christophe; Micoud, Pierre; Meunier, Jean-François; Martin, François; Corvo, Marta C.; Almeida, Pedro L.; Einloft, SandraNano-Fe3O4-synthetic talc gel was used as filler in the synthesis of waterborne polyurethane/Fe3O4-synthetic talc nanocomposites. This filler presents numerous edges (Si-O and Mg-O) and OH groups easily forming hydrogen bonds and polar interaction with water conferring hydrophilic character, consequently improving filler dispersion within a water-based matrix. Yet, the use of waterborne polyurethane (WPU) as matrix must be highlighted due to its environmentally friendly characteristics and low toxicity compared to solvent-based product. Fe3O4-synthetic talc-nanofillers were well dispersed into the polyurethane matrix even at high filler content as supported by XRD and TEM analyses. NMR indicates the interaction of filler OH groups with the matrix. For all nanocomposites, one can see a typical ferromagnetic behavior below Curie temperature (about 120 K) and a superparamagnetic behavior above this temperature. The use of Fe3O4-synthetic talc for obtaining magnetic nanocomposites resulted in improved materials with superior mechanical properties compared to solvent-based nanocomposites.