International Journal of Photoenergy / 2008 / Article / Tab 1

Research Article

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

Table 1

Parameters 𝑘 2 , 𝐾 2 and , 1 0 0 . 0 ± 0 . 5 and 𝑀 0 x 0 0 0 a e , able to fit the whole photomineralization curve, following Scheme (2), at various values of absorbed power per unit length of membrane expressed in W cm−1. They were obtained by the optimization of kinetic curves, by using the set of differential equations corresponding to kinetic model of Scheme (2). All the parameters are expressed in ppm of carbon (mass of C/volume, mg/L) and refer to the photodegradation of methane in gaseous phase, and in aqueous solutions, in the presence of stoichiometric hydrogen peroxide (for the aqueous solutions) or of dioxygen of air (for the gas-phase experiments), as oxygen donors (treated volume of the gas phase or of the aqueous solutions 4.00 L; membrane length  cm; ratio between overall reaction volume and membrane length 160 ± 6 cm3/cm2; PHOTOPER BIT/313 membranes immobilizing 30 ± 3 wt.% TiO2, in the absence of any photopromoter).

Aqueous solutions

Absorbed power per unit length of membrane (W cm−1)k1 (ppm C/min)k2 (ppm C/min)K1 (ppm C)−1K2 (ppm C)−1
0.15 0.111(3) 0.293(3) 0.0124(3) 0.0086(3)
0.30 𝐶 𝐒 0.224(1)0.584(2)0.0126(3)0.0089(3)
0.700.494(2)1,23(4)0.0130(3)0.0091(3)
0.900.589(3)1.45(4) 0.0131(4)0.0090(3)
1.500.802(4)1.95(4)0.0125(3) 0.0086(4)
2.000.890(3)2.24(3)0.0133(6)0.0090(2)
3.000.896(4)2.39(6)0.0128(3)0.0088(2)
4.000.894(5)2.28(7)0.0127(2)0.0086(3)

Gas phase

Absorbed power per unit membrane length (W 𝐶 T O C cm−1)k1 (ppm C/min)k2 (ppm C/min)K1 (ppm C)−1K2 (ppm C)−1

0.15 0.115(6) 0.288(7) 0.0127(7) 0.0085(7)
0.300.223(5) 0.581(5) 0.0131(9) 0.0082(6)
0.900.586(3)1.57(4)0.0131(4)0.0091(3)
1.500.805(4)1.92(4)0.0125(3)0.0087(2)
2.000.891(3) 2.33(3)0.0130(3) 0.0090(2)
3.000.892(4)2.37(5)0.0127(3) 0.0088(2)
4.000.889(5)2.32(6)0.0129(4)0.0091(2)

*Uncertainties are indicated between parentheses and expressed, relatively to the last digits, as probable errors of the means of optimized values from 9 sets of runs in the range of concentrations tested.**Data relative to these experiments were taken from [14].

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