The structural and surface changes in a phenylene-bridged periodic mesoporous organosilica after thermal treatment under different conditions are reported. Organic moieties in the pore walls are stable at temperatures close to 500 C but calcination in the presence of oxygen leads to C-Si bond cleavage as well as the formation of oxidized groups of phenolic and carbonyl type. The oxidized materials are functionalized by reaction with chlorosulfonic acid in a higher extension than those calcined under nitrogen but all of them preserve their structure and surface properties. All sulfonated organosilicas were active as catalysts for the esterification of acetic acid with ethanol, particularly those calcined in the air. Remarkably, some of them can be even more active than Amberlyst-15 when water is used as reaction medium which is of a high interest for the design of sustainable acid-catalyzed chemical processes.

Graphene-based materials are highly interesting in virtue of their excellent chemical, physical and mechanical properties that make them extremely useful as privileged materials in different industrial applications. Sonochemical methods allow the production of low-defect graphene materials, which are preferred for certain uses. Graphene nanosheets (GNS) have been prepared by exfoliation of a commercial micrographite (MG) using an ultrasound probe. Both materials were characterized by common techniques such as X-ray diffraction (XRD), Transmission Electronic Microscopy (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). All of them revealed the formation of exfoliated graphene nanosheets with similar surface characteristics to the pristine graphite but with a decreased crystallite size and number of layers. An exhaustive study of the particle size distribution was carried out by different analytical techniques such as dynamic light scattering (DLS), nanoparticle tracking analysis (NTA) and asymmetric flow field flow fractionation (AF4). The results provided by these techniques have been compared. NTA and AF4 gave higher resolution than DLS. AF4 has shown to be a precise analytical technique for the separation of GNS of different sizes.

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