Coupling of photocatalysis and catalysis using an optical fiber textile for room temperature depollution.

Herein, we investigate the interplay between a photocatalyst (TiO2) and a catalyst (Pt/TiO2 and Pt/CeO2) for the oxidation of formaldehyde and toluene at room temperature. A luminous textile is used as support and as light source for the photocatalyst. Our results indicate that the presence of the catalyst and the photocatalyst increases the catalytic performance for the oxidation of formaldehyde, while the photocatalytic performance for toluene oxidation decreases. The overall performance (toluene and formaldehyde degradation) of the system can be optimized with respect to the choice of support for the catalyst (e.g. TiO2 or CeO2), the quantity of Pt used, and the ratio between the catalyst and photocatalyst. In addition, different configurations of the photocatalyst and the catalyst on the textile are studied: under leaching and flow-through gas streams, catalyst and photocatalyst deposition on the same and opposite site of the textile are tested. The performance of the system can be optimized by adapting a configuration where the gas stream goes through the textile, while the deposition side of the catalyst and/or photocatalyst with respect to the gas stream is of minor importance.

Evaluation of adsorbents for volatile methyl siloxanes sampling based on the determination of their breakthrough volume.

Volatile methyl siloxanes (VMS) have been detected in many different atmospheres such as biogas, sewage sludge, landfill gas, gasoline and ambient air. In these different atmospheres, their presence can involve several contamination problems and negative effects in industrial processes, their identification and quantification become a real challenge. Up to now there is no standardized procedure for VMS quantification, the sampling step remaining the major obstacle. Sampling gas through sorbent tube followed by analysis on TD-GC-MS is one of the reliable possibilities. It gathers sampling and preconcentration in one step and allows discrimination between all VMS, despite the difficulty to choose the appropriate adsorbent in order to avoid loss of analytes during sampling. In this context, this work deals with the comparison of different types of adsorbents based on the determination of the VMS breakthrough volume (BV). Although Tenax TA is the most widely used adsorbent, experiments show low BV values for the lightest VMS. At 25°C, the BV of TMS and L2 are, respectively, 0.2 and 0.44 L g(-1) which can contribute to an underestimation in concentration during their quantification. Carbosieve SIII usually used for C2-C5, did not adsorb light VMS as it was expected, and breakthrough volume obtained for VMS are more than ten times less than the values obtained for Tenax. On other hand, Chromosorb 106 and Carboxen 1000 in association with Carbotrap C and Carbotrap proved to be appropriated for VMS sampling, due to the high breakthrough volumes obtained for the lightest compounds comparing to the other adsorbents. The BVs of TMS for Carboxen 1000 and Chromosorb 106 are 1.2 × 10(4) and 39 L g(-1), respectively, and 49 × 10(4) and 1142 L g(-1) for L2, respectively.