Removal of TiO 2 nanoparticles from water by low pressure pilot plant filtration

Rising use of nanoparticles in manufacturing as well as in commercial products bring issues related to environmental release and human exposure. A large amount of TiO2 nanoparticles will eventually reach wastewater treatment plants. Low pressure membrane filtration has been suggested as a feasible treatment of water streams. This study investigated first at laboratory scale the influence of: i) membrane material, ii) pore size and iii) water chemistry on nTiO2 removal. TiO2 retention was governed by the cake layer formation mechanism and significant retention of nanoparticles was observed even for filters having considerably larger pores than nTiO2. PVDF showed a great potential for nTiO2 rejection. Additionally, filtration pilot plant experiments were carried out using PVDF membranes (0.03 and 0.4 μm pore size). The release of nTiO2 in the pilot scale filtration system was always above the instrumental detection limit (> 1.5 μg/L) and in most cases below 100 μg/L regardless of the pore size and applied conditions. The nTiO2 membrane breakthrough predominantly occurred in the first few minutes after backwashes and ceased when the cake layer was formed. Ultrafiltration and microfiltration were comparable with rejection of nTiO2 above 95% at similar permeate flow rates. Nevertheless, ultrafiltration is more promising than microfiltration because it allowed longer operation times between backwash cycles.This work was funded by the Provincial Government of Bizkaia (6-12-TK-2010-0013)

Stacked wire-mesh monoliths for VOCs combustion: Effect of the mesh-opening in the catalytic performance

Structured reactors based on low cost metallic wire-mesh substrates of highly enhanced transport properties can be an interesting alternative to parallel channel monolithic reactors. In this work stacked wire-mesh monoliths were studied for volatile organic compounds elimination. Monoliths of different mesh-opening were homogeneously and adherently dip-coated with Pt/Manganese Octahedral Molecular Sieve (OMS-2) bifunctional catalyst. The catalytic activity was tested in toluene and methanol complete oxidation reactions. Catalytic activity increases using stacked wire-mesh monoliths instead of parallel channel monoliths and decreases when increasing the wire-mesh opening, showing the importance of the mass-transfer phenomena (contact between the gas phase and the solid catalyst).Fil: Sanz, Oihane. Universidad del País Vasco; EspañaFil: Banus, Ezequiel David. Universidad del País Vasco; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Goya, Aintzane. Universidad del País Vasco; EspañaFil: Larumbe, Haizea. Universidad del País Vasco; EspañaFil: Delgado, Juan José. Universidad de Cádiz; EspañaFil: Monzón, Antonio. Universidad de Cádiz; EspañaFil: Montes, Mario. Universidad del País Vasco; Españ