Identification by GC-MS Analysis of Organics in Manufactured Articles through a D-Optimal Design

Many manufactured articles are made of composite materials often bonded by a phenolic resin. Through a D-optimal design, we optimized a method to characterize phenolic resins after the extraction process by GC-MS analysis. The study was conducted on three different phenolic resins and four manufactured articles with the same inorganic composition and different analyzed binders. Moreover, three cardanol resins that differ in their production systems were analyzed to see if there were differences between them. Through Soxhlet extraction with dichloromethane or acetone, it is possible to differentiate the raw materials through characteristic compounds and to identify them in the manufactured articles

Electron transfer and H2 evolution in hybrid systems based on [FeFe]-hydrogenase anchored on modified TiO2

© 2016 Hydrogen Energy Publications LLC The hybrid systems composed by [FeFe]-hydrogenase anchored to the surface of three distinct types of TiO2 (anatase) have been investigated using Electron Paramagnetic Resonance (EPR) spectroscopy in dark and under illumination. The three supports were bare TiO2 nitrogen doped TiO2 (N-TiO2) and a sub-stoichiometric form of the same oxide (TiO2−x) exhibiting blue color. EPR spectroscopy has shown that the electrons photogenerated by irradiation of the supports are stabilised by the solid forming Ti3+ paramagnetic ions while, in the case of the hybrid systems electrons are scavenged by the anchored protein becoming available for H+ reduction. The ability of the three hybrid systems in hydrogen production under solar light illumination has been compared. The formation of H2 is higher for the system containing N-TiO2 (yellow) with respect to that based on the bare oxide (white) indicating that the visible light absorbed, due to the presence of N states, is actually exploited for hydrogen production. The system containing reduced blue TiO2, in spite of its deep coloration, is less active suggesting that a specific type of visible light absorption is needed to produce photoexcited electrons capable to interact with the anchored protein

Structural, electronic and photochemical properties of cerium-doped zirconium titanate

Mixed solid system involving cerium and zirconium titanate (ZrTiO4) have been prepared using the sol-gel technique. Both X-ray diffraction and DFT calculations firmly indicate that, till a doping level of 10 mol%, cerium ions are dissolved in the titanate matrix (which has the scrutynite structure, analogous to those of the main TiO2 polymorphs) occupying the cationic sites and progressively altering its cell parameters. Cerium is hosted in the matrix both in the form of Ce4+ and Ce3+ ions (XPS results). The trivalent state seems to be favoured even though the state of the dopant depends on the treatment undergone by the material. DFT calculations describe the intra-band gap states formed in both cases and the strong localisation of the single electron in the case of Ce3+ (4f1). Differently from the case of Ce doped ZrO2, that shows photoactivity in the visible light because of the presence of cerium, the doped titanate is inactive in the same conditions. Under UV\u2013vis illumination charge separation occurs (EPR results) and the low-loading doped systems (0.5%, 1%) form OH radicals, detected by spin trapping, more efficiently than the pristine matrix. The absence of photoactivity in the visible range is interpreted in terms of the detrimental role (charge recombination) played by both the occupied intra-band gap states associated to Ce3+ and the corresponding oxygen vacancies formed in the lattice by charge compensation

Beyond TiO2: Cerium-Doped Zinc Oxide as a New Photocatalyst for the Photodegradation of Persistent Pollutants

We prepared via hydrothermal synthesis zinc oxide samples doped with cerium. The samples were characterized via powder X-Ray Diffraction measurements, Diffuse Reflectance UV Vis spectroscopy, Scanning Electron Microscopy and Transmission Electron Microscopy with EDX (Energy Dispersive X-Ray spectroscopy) analysis, and BET (Brunauer-Emmett-Teller) surface area analysis. XRD measurements reveal the formation of highly crystalline materials; wurtzite is the most important. All materials were tested using phenol as model molecule and their performances were compared with TiO2 P25. The material showing the best performance, namely Ce-doped ZnO, was then used to abate some emerging pollutants. We chose three iodinated X-ray contrast agent (ICM), iopromide, iopamidol and diatrizoate, known to be recalcitrant to traditional advanced oxidation processes. In the presence of TiO2 P25, all ICM exhibited a slow degradation, with t(1/2) ranging from 30 min (iopamidol) to 120 min (diatrizoate) and several hours are required for their complete disappearance. The employment of Ce-doped ZnO leads to a sharp increase in their disappearance, with t(1/2) obtained within 15 min (iopamidol) or 25 min (diatrizoate) and the complete abatement is achieved within 2 h