Special preparation of Santa Barbara Amorphous (SBA)-15, mesoporous silica with highly hexagonal ordered, these materials have been carried out for creating adsorbents exhibiting an enhanced and partially selective adsorption toward CO2. This creation starts from an adequate conditioning of the silica surface, via a thermo-alkaline treatment to increase the population of silanol species on it. CO2 adsorption is only reasonably achieved when the SiO2 surface becomes aminated after put in contact with a solution of an amino alkoxide compound in the right solvent. Unfunctionalized and amine-functionalized substrates were characterized through X-ray diffraction, N2 sorption, Raman spectroscopy, electron microscopy, 29Si solid-state Nuclear Magnetic Resonance (NMR), and NH3 thermal programmed desorption. These analyses proved that the thermo-alkaline procedure desilicates the substrate and eliminates the micropores (without affecting the SBA-15 capillaries), present in the original solid. NMR analysis confirms that the hydroxylated solid anchors more amino functionalizing molecules than the unhydroxylated material. The SBA-15 sample subjected to hydroxylation and amino-functionalization displays a high enthalpy of interaction, a reason why this solid is suitable for a strong deposition of CO2 but with the possibility of observing a low-pressure hysteresis phenomenon. Contrastingly, CH4 adsorption on amino-functionalized, hydroxylated SBA-15 substrates becomes almost five times lower than the CO2 one, thus giving proof of their selectivity toward CO2. Although the amount of retained CO2 is not yet similar to or higher than those determined in other investigations, the methodology herein described is still susceptible to optimization.
Composite materials are used in bone tissue engineering because they mimic the structure of the extracellular matrix of bone. In this work, polylactic acid (PLA) fiber scaffolds prepared by air-jet spinning technique, were doped with different concentrations of SBA-15 ceramic (0.05, 0.1, and 0.15 wt%). The SBA-15 ceramic powder was made by the Sol-Gel process. Physicochemical characterization of PLA, SBA-15, and composite fiber scaffold was done by XRD, SEM, BET, FTIR, TGA, mechanical test, and biocompatibility assay, which were performed in a cell culture model with osteoblast cells. Our results showed a random nanofibers composite scaffold with an improvement in the physicochemical properties. The PLA fiber diameter increases as increases the content of SBA-15, and the mechanical properties were dose-dependent. SBA-15 shows the well-ordered mesoporous hexagonal structure with a pore size of 5.8 ± 0.2 nm and a specific surface area with a value of 1042 ± 89 m 2 /g. PLA fibers and composites have thermal stability up to 300°C, and thermal decomposition in the range 316-367°C. In vitro biocompatibility results showed that PLA/SBA-15 composite scaffold had no cytotoxicity effect in terms of cell adhesion and viability of osteoblast cells. Furthermore, the doped SBA-15 with 0.05% wt onto the polymer matrix could be useful in biomedical applications for bone tissue engineering.
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