Influence of irradiance, flow rate, reactor geometry, and photopromoter concentration in mineralization kinetics of methane in air and in aqueous solutions by photocatalytic membranes immobilizing titanium dioxide
Articolo
Data di Pubblicazione:
2008
Citazione:
Influence of irradiance, flow rate, reactor geometry, and photopromoter concentration in mineralization kinetics of methane in air and in aqueous solutions by photocatalytic membranes immobilizing titanium dioxide / I.R. Bellobono, M. Rossi, A. Testino, F. Morazzoni, R. Bianchi, G. De Martini, P.M. Tozzi, R. Stanescu, C. Costache, L. Bobirica, M.L. Bonardi, F. Groppi. - In: INTERNATIONAL JOURNAL OF PHOTOENERGY. - ISSN 1110-662X. - 2008(2008), pp. 283741.283741.1-283741.283741.14. [10.1155/2008/283741]
Abstract:
Photomineralization of methane in air (10.0–1000 ppm (mass/volume) of C) at 100% relative humidity (dioxygen as oxygen
donor) was systematically studied at 318 ± 3 K in an annular laboratory-scale reactor by photocatalytic membranes immobilizing
titanium dioxide as a function of substrate concentration, absorbed power per unit length of membrane, reactor geometry,
and concentration of a proprietary vanadium alkoxide as photopromoter. Kinetics of both substrate disappearance, to yield intermediates,
and total organic carbon (TOC) disappearance, to yield carbon dioxide, were followed. At a fixed value of irradiance
(0.30W·cm−1), the mineralization experiments in gaseous phase were repeated as a function of flow rate (4–400m3·h−1). Moreover,
at a standard flow rate of 300m3·h−1, the ratio between the overall reaction volume and the length of the membrane was
varied, substantially by varying the volume of reservoir, from and to which circulation of gaseous stream took place. Photomineralization
of methane in aqueous solutions was also studied, in the same annular reactor and in the same conditions, but in a
concentration range of 0.8–2.0 ppm of C, and by using stoichiometric hydrogen peroxide as an oxygen donor. A kinetic model was
employed, from which, by a set of differential equations, four final optimised parameters, k1 and K1, k2 and K2, were calculated,
which is able to fit the whole kinetic profile adequately. The influence of irradiance on k1 and k2, as well as of flowrate on K1 and K2,
is rationalized. The influence of reactor geometry on k values is discussed in view of standardization procedures of photocatalytic
experiments. Modeling of quantum yields, as a function of substrate concentration and irradiance, as well as of concentration of
photopromoter, was carried out very satisfactorily. Kinetics of hydroxyl radicals reacting between themselves, leading to hydrogen
peroxide, other than with substrate or intermediates leading to mineralization, were considered, and it is paralleled by a second
competition kinetics involving superoxide radical anion.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
PILOT-PLANT PHOTOMINERALIZATION ; PROMOTING PHOTOCATALYSTS ; PHOTOSYNTHETIC MEMBRANES ; SCALE PHOTODEGRADATION ; LABORATORY-SCALE ; SEMICONDUCTOR PHOTOCATALYSIS ; MODEL MOLECULE ; N-ALKANES ; PHENOL ; POLYMERS
Elenco autori:
I.R. Bellobono, M. Rossi, A. Testino, F. Morazzoni, R. Bianchi, G. De Martini, P.M. Tozzi, R. Stanescu, C. Costache, L. Bobirica, M.L. Bonardi, F. Groppi
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