Tânia Lopes

Permeation of d5-2,4,6-Trichloroanisole via Vapor Phase through Different Closures into Wine Bottles

This study examined the sealing effectiveness of different closures on the permeation of exogenous compounds when bottled wine model solutions were stored in a contaminated environment with deuterium-labeled 2,4,6-trichloroanisole (d5-TCA). Wine model solutions and closure fractions (outer, middle, and inner) were assessed over time for the concentration of releasable d5-TCA by SPME-GC-MS. During 24 months of storage, high concentrations of d5-TCA were essentially retained in the outer portions of natural and microagglomerate corks. Under the conditions of this experiment, the natural and microagglomerate cork stoppers were effective barriers to the transmission of exogenous contaminants. Conversely, d5-TCA penetrated synthetic closures and contaminated the wine.

TiO2-coated window for facilitated gas evolution in PEC solar water splitting

Photoelectrochemical (PEC) cells for water splitting generally have a transparent front window for the sunlight to reach the surface of the photoelectrode or tandem photoelectrode. The overall efficiency of a PEC system for solar hydrogen production is strongly affected by the evolved gases that get trapped in the front window. This negative effect is clearly observed when the PEC cells are placed in tilted positions to maximize light harvesting. Titanium dioxide coatings become superhydrophilic when exposed to UV light, facilitating the gas bubbles to slip up. The present study focuses on the development of a thin TiO2 coating to minimize the adhesion of the evolved bubbles in the front window of PEC cells, thereby maximizing its transparency. Highly transparent, crack-free, and stable thin films of TiO2 were prepared by spin coating followed by sintering at 465 °C for 45 min. A water contact angle (WCA) of 0° was obtained after irradiating the surface of the sample for 30 min with UV-light (365 nm, 2 W m−2), confirming the superhydrophilic behaviour. The irradiance loss during the evolution of H2/O2 was assessed using a silicon PV cell; the cell, tilted at 45° and equipped with a TiO2-coated glass window, showed ca. 10% higher irradiance as compared to the uncoated glass window cell for both hydrogen and oxygen evolutions, whereas no significant differences were observed when the cells were vertically placed.