Search results for " urban pollution"
showing 2 items of 2 documents
Environmental impact on historical monuments: The black crusts of the Venice lagoon
2020
Black crusts are typical decay forms on calcareous rocks in polluted urban environments. Their origin is due to “sulphation” reaction of calcium carbonate substrates (CaCO3), as a consequence of pH value decrease caused by SO2 in the polluted atmosphere. They can be therefore defined as a passive air pollution sampler. For the purpose of this work, samples from the historic center of Venice were analyzed. The city of Venice suffers in particular maritime and industrial pollution (Marghera industrial zone). By means of minero-petrographic and geochemical analyses, it was possible to obtain information on the mineralogy of the crust and its interaction with the underlying substrates, other th…
Photocatalytic activity of TiO2/SiO2 systems
2009
Silica-supported TiO(2) powders were synthesized by a wet method under mild conditions. The aim of the work was the preparation of TiO(2)/SiO(2) additives for photocatalytic cements. Three types of commercial SiO(2) were used as supports: Cabot, Axim and Fly Ash. Cabot silica was ultra-pure whereas the other two silica contained different percentages of various oxides. The TiO(2)/SiO(2) samples, denoted TiO(2)/Cabot, TiO(2)/Axim and TiO(2)/Fly Ash, were prepared by boiling suspensions obtained by addition of silica to a solution of TiCl(4) in water (volume ratio 1:10). The photocatalytic activity was evaluated in a gas-solid system both in batch and in continuous reactors using 2-propanol a…