Jorge Bedia

Recent Inventions in Glycerol Transformations and Processing

Many patents claiming new processes for the conversion of glycerol into valuable-added chemicals are appearing in recent years as a result of glycerol availability since it is the main by-product in the biodiesel production and in other processes concerning biomass as raw material. In a future biorefinery glycerol will remain as a platform molecule. Present review describes a selection of such patents and shows the potential of glycerol as raw material in such future chemical industries (biorefineries).

Influence of Water Vapor on the Adsorption of VOCs on Lignin‐Based Activated Carbons

Abstract Activated carbons with a wide range of burn‐off degrees obtained from Eucalyptus kraft lignin have been used to study the influence of the presence of water vapor on VOCs adsorption. The amount adsorbed and the rate of adsorption of both benzene and water vapor increase with activated carbon burn‐off as a consequence of an increase of micropore volume, broadening of micropore size distribution and increasing development of meso‐ and macroporosity. Similar results were found for MEK and methanol. Benzene is only partially desorbed at the adsorption temperature and an appreciable amount of it remains in the carbon, most likely in the narrow micropores. On the contrary, water vapor is completely desorbed at the adsorption temperature and its adsorption profile clearly exhibits two steps with different adsorption rates, associated to water molecules adsorbed on the active sites given rise to cluster formation and further migration and filling of the micropores. Adsorption with mixtures of VOC and water vapor has been carried out. The total amount adsorbed by the carbon, near the equilibrium point, is higher than in the case of the stream containing only the VOC. The adsorption rates for the mixtures streams are similar to that for the corresponding streams containing only the VOC in the case of carbons with a well developed porous structure. However, the presence of water vapor increases the rate of adsorption on the activated carbons with narrower microporosity. Saturation of the activated carbon with water vapor prior to the adsorption of a mixture containing benzene and water vapor has shown little effect on the amount of benzene adsorbed, suggesting that water and benzene molecules are adsorbed in different sites on the carbon surface.

Ag-Coated Heterostructures of ZnO-TiO2/Delaminated Montmorillonite as Solar Photocatalysts

Heterostructures based on ZnO-TiO2/delaminated montmorillonite coated with Ag have been prepared by sol–gel and photoreduction procedures, varying the Ag and ZnO contents. They have been thoroughly characterized by XRD, WDXRF, UV–Vis, and XPS spectroscopies, and N2 adsorption, SEM, and TEM. In all cases, the montmorillonite was effectively delaminated with the formation of TiO2 anatase particles anchored on the clay layer’s surface, yielding porous materials with high surface areas. The structural and textural properties of the heterostructures synthesized were unaffected by the ZnO incorporated. The photoreduction led to solids with Ag nanoparticles decorating the surface. These materials were tested as photocatalysts for the degradation of several emerging contaminants with different nitrogen-bearing chemical structures under solar light. The catalysts yielded high rates of disappearance of the starting pollutants and showed quite stable performance upon successive applications.

Coaxial Electrospinning for Nanostructured Advanced Materials

Electro-hydro-dynamic (EHD) compound jets, with diameters in the micro and nanometric size range, from conical menisci of two co-flowing liquids, is a consolidated platform for the production of nanofibers with inner structure, in a process so-called coaxial electrospinning or co-electrospinning. In contrast to other multi-step template based procedures, the EHD methodology is much more simple and general since, firstly, a solid template is needless and, secondly, the process is seldom affected by the chemistry of the liquids. This gentle process allows selecting the liquid precursors depending on the application sought for the nanofibers. Here, we review different products obtained by this EHD technique: (1) solid and hollow carbon nanofibers from different precursors (polyacrylonitrile, polyvinylpyrrolidone and lignin), (2) nanofibers of biocompatible polymers encapsulating liquids in the form of beads, (3) spinning nanofibers of alginate and (4) in-fiber encapsulation of active microgels.