Comparison of kinetics of acetone, heptane and toluene photocatalyticmineralization over TiO2microfibers and Quartzel®mats
Résumé
The kinetic parameters for VOCs (acetone, toluene, heptane) mineralization of lab-extruded pure TiO2fibers prepared under easily scalable conditions were compared with those of a commercial photo-catalytic media from Saint-Gobain, Quartzel®, under identical conditions. A flow-through recirculatingreactor loop with variable LEDs irradiation at 365 nm was specially designed. All the experiments werecarried out in a continuous recycle mode. Both types of fibers were very efficient for acetone and hep-tane mineralization. At 20% relative humidity (RH), the reaction rates were higher with the commercialmedia, whereas at 60% RH the catalysts displayed equal activity for acetone conversion. Toluene min-eralization was much faster on these lab-made fibers than on Quarztel®, which was more sensitiveto poisoning by reaction by-products. At 20% relative humidity, with the lab-made TiO2fibers, typicalquantum efficiencies were, respectively, 0.0106 and 0.0027 for acetone and heptane (100 ppmV initialconcentration) and 0.0024 for toluene (200 ppmV initial concentration) while these quantum efficiencieswere 0.0358, 0.0133 and 0.0011 with expanded Quartzel fibers under the same conditions. These resultsevidence a clear difference in the VOCs, water and polar by-products adsorption between these two kindsof fibers.These newly developed fibers can be produced at an industrial scale with a proven efficiency for VOCsdegradation and mineralization. Since they are less sensitive to humidity than the commercial fibers,they could be most useful under actual ambient air conditions. These fibers present a good alternative toother commercially available photocatalytic media for gas phase purification.