Microporous silica solids of SiO 2 and Ag/SiO 2 (a microporous SiO 2 substrate containing 5 wt % Ag) are synthesized by the sol-gel method and analyzed through several characterization techniques. The type I shapes of N 2 sorption isotherms at 76 K on these materials indicate large micropore contents as well as important cohesive interactions between adsorbed N 2 molecules, i.e., a gradual cooperative filling process becomes more and more evident as the concentration of adsorbate within the porous structure increases. In addition, negative values of the BET constant are found thus indicating that the adsorption mechanism on these solids can be better described in terms of a volume filling process rather than in terms of a multilayer formation phenomenon. The microporosity existing in these substrata is studied through Sing's R s -plots. The adsorption capacities of n-alkanes (i.e. n-hexane, n-heptane, n-octane, and n-nonane) on SiO 2 and Ag/SiO 2 substrata are measured by gas chromatography (GC) at different temperatures. The uptake of every hydrocarbon sorptive, on both SiO 2 and Ag/SiO 2 substrata, is found to be temperaturedependent. Additionally, the intensities of attractive interactions between hydrocarbon ad molecules and the surfaces of the above solids are evaluated for each adsorbate type from determinations of the isosteric heats of adsorption.
Our research group has developed a group of hybrid biomedical materials potentially useful in the healing of diabetic foot ulcerations. The organic part of this type of hybrid materials consists of nanometric deposits, proceeding from the Mexican medicinal plantTournefortia hirsutissimaL., while the inorganic part is composed of a zeolite mixture that includes LTA, ZSM-5, clinoptilolite, and montmorillonite (PZX) as well as a composite material, made of CaCO3and montmorillonite (NABE). The organic part has been analyzed by GC-MS to detect the most abundant components present therein. In turn, the inorganic supports were characterized by XRD, SEM, and High Resolution Adsorption (HRADS) of N2at 76 K. Through this latter methodology, the external surface area of the hybrid materials was evaluated; besides, the most representative textural properties of each substrate such as total pore volume, pore size distribution, and, in some cases, the volume of micropores were calculated. The formation and stabilization of nanodeposits on the inorganic segments of the hybrid supports led to a partial blockage of the microporosity of the LTA and ZSM5 zeolites; this same effect occurred with the NABE and PZX substrates.
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