TY - JOUR
T1 - A mechanism of photocatalytic and adsorptive treatment of 2,4-dinitrophenol on a porous thin film of TiO2 covering granular activated carbon particles
AU - Cao, Xiangyu
AU - Shiraishi, Fumihide
PY - 2010/6
Y1 - 2010/6
N2 - The present work investigates the mechanism of the photocatalytic and adsorptive treatment of an aqueous DNP (2,4-dinitrophenol) solution in an annular-flow reactor installed with a TiO2/AC-PET film (a polyethylene terephthalate film adhesively fixing activated carbon particles covered with a thin and porous film of titanium dioxide). Unfortunately, the experimental result indicates that it is impossible to correctly measure the time courses of product ion concentrations because they are adsorbed onto or desorbed from AC particles. Therefore, a computer simulation methodology using mathematical models is introduced in order to elucidate the treatment mechanism. Treatments of aqueous DNP solutions using the TiO2-PET film reveal that the diffusion of DNP from a bulk solution to a TiO2 film is based on the gradient of DNP concentration, generated by a rapid adsorption of DNP onto AC and photocatalytic reaction, in the very neighborhood of TiO2 film, and this diffusion increases the DNP concentration at the surface of TiO2 film, thereby enhancing the rate of photocatalytic decomposition. Moreover, it is found that the TiO2/AC-PET film can lower the burden of the adsorption of DNP onto AC compared with the AC-PET film because a part of DNP molecules are photocatalytically decomposed and the percentage of this decomposition is increased at a lower linear velocity. In conclusion, the mathematical model taking into consideration a film-diffusional effect can successfully explain the complicated mechanism of the treatment of an aqueous DNP solution using the TiO2/AC-PET film.
AB - The present work investigates the mechanism of the photocatalytic and adsorptive treatment of an aqueous DNP (2,4-dinitrophenol) solution in an annular-flow reactor installed with a TiO2/AC-PET film (a polyethylene terephthalate film adhesively fixing activated carbon particles covered with a thin and porous film of titanium dioxide). Unfortunately, the experimental result indicates that it is impossible to correctly measure the time courses of product ion concentrations because they are adsorbed onto or desorbed from AC particles. Therefore, a computer simulation methodology using mathematical models is introduced in order to elucidate the treatment mechanism. Treatments of aqueous DNP solutions using the TiO2-PET film reveal that the diffusion of DNP from a bulk solution to a TiO2 film is based on the gradient of DNP concentration, generated by a rapid adsorption of DNP onto AC and photocatalytic reaction, in the very neighborhood of TiO2 film, and this diffusion increases the DNP concentration at the surface of TiO2 film, thereby enhancing the rate of photocatalytic decomposition. Moreover, it is found that the TiO2/AC-PET film can lower the burden of the adsorption of DNP onto AC compared with the AC-PET film because a part of DNP molecules are photocatalytically decomposed and the percentage of this decomposition is increased at a lower linear velocity. In conclusion, the mathematical model taking into consideration a film-diffusional effect can successfully explain the complicated mechanism of the treatment of an aqueous DNP solution using the TiO2/AC-PET film.
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U2 - 10.1016/j.cej.2010.04.006
DO - 10.1016/j.cej.2010.04.006
M3 - Article
AN - SCOPUS:77954814146
VL - 160
SP - 651
EP - 659
JO - Chemical Engineering Journal
JF - Chemical Engineering Journal
SN - 1385-8947
IS - 2
ER -