Interaction of the Indoor Air Pollutant Acetone with Degussa P25 TiO₂ Studied by Chemical Ionization Mass Spectrometry

Abstract

Preventing a build-up of indoor pollutant concentrations has emerged as a major goal in environmental chemistry. Here, we have applied chemical ionization mass spectrometry to study the interaction of acetone, a common indoor air pollutant, with Degussa P25 TiO2, an inexpensive catalyst that is widely used for the degradation of volatile organic compounds into CO2 and water. To better understand the adsorption of acetone onto Degussa P25, the necessary first step for its degradation, the experiments were carried out at room temperature in the absence of UV light. This allowed for the deconvolution of the nonreactive and reactive thermal binding processes on Degussa P25 at acetone partial pressures (10(-7)-10(-4) Torr) commonly found in indoor environments. On average, 30% of the adsorbed acetone is bound irreversibly, resulting in a surface coverage of irreversibly bound acetone of approximately 1 x 10(12) molecules/cm2 at 3-4 x 10(-5) Torr. Equilibrium and dynamic experiments yield a sticking coefficient of approximately 1 x 10(-4) that is independent of the acetone partial pressures examined here. Equilibrium binding constants and free energies of adsorption are reported.

Heating rate dependence of anatase to rutile transformation

“…Therefore a great quantity of research has been brought out to study the preparation, anomalous behaviour and potential applications of this material [6][7][8][9][10][11][12]. Today, the titania powder is mainly used in the anatase form in applications such as solar energy storage cells [13,14], catalysts and degradation of organic compounds [15][16][17][18][19][20]. Rutile does not show the high photoreactivity of anatase [21] and is used mainly for pigments due to its effective high light scattering [22] and also for its large static dielectric constant [19,23].…”

“…Today, the titania powder is mainly used in the anatase form in applications such as solar energy storage cells [13,14], catalysts and degradation of organic compounds [15][16][17][18][19][20]. Rutile does not show the high photoreactivity of anatase [21] and is used mainly for pigments due to its effective high light scattering [22] and also for its large static dielectric constant [19,23]. Moreover there are many researches that have demonstrated rutile's photocatalytic activity similar to anatase when the crystal size of both phases was comparable [24].…”

A highly sensitive BTX sensor based on electrochemically derived wall connected TiO2 nanotubes

“…Therefore, low temperature sensing of aromatic hydrocarbon on oxide surface can be explained through Langmuir-Hinshelwood (L-H) approach which depicts that, the test molecules are physisorbed first then take part in the subsequent chemisorption [29]. The amount of physisorbed molecules depends on the sticking coefficient which is also proportionate to collision flux (Z w ) [35] and can be expressed as,…”

Structure, Morphology, and Faceting of TiO2 Photocatalysts by the Debye Scattering Equation Method. The P25 and P90 Cases of Study

“…Commercial pyrogenic titania samples, marketed under the P25 and P90 labels, have been widely investigated to understand the relationship between structure, size, and their excellent photocatalytic properties [27][28][29][30][31][32][33][34][35][36]. The presence of a small amount of rutile nanoparticles (10-15% by weight) in these materials has been suggested to have an active role, serving as "antenna" or photosensitizer extending the anatase band gap and thus improving its photocatalytic activity [37][38][39].…”