共查询到20条相似文献,搜索用时 31 毫秒
1.
Chongyang Zhou Yuren Jin Hui Xu Shujuan Feng Guoqing Zhou Junfu Liang Jingming Xu 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(1):251-256
The Wheeler–Jonas equation (WJ equation) is widely used to predict breakthrough of volatile organic compounds on granular
activated carbon (GAC) and the most important criteria is to calculate the overall adsorption rate constant (k
v
) and amount adsorbed based on breakthrough curve. The operational factors, including temperatures, concentrations and flow
rates, for packed bed, can affect the values of k
v
more or less and to what degree has not yet been systematically investigated. What’s more, the relation between the dynamic
adsorption coefficient (k
d) or Henry constant, which is used for the design of packed bed, and WJ equation is not clear. In order to solve these problems,
we performed xenon dynamic adsorption on GAC adsorber experiments under different values of xenon concentrations, flow rates
and temperatures, obtained the breakthrough curves for elution times versus xenon concentrations, and then employed WJ equation
to explain breakthrough curves. The experimental results indicate that the WJ equation can fit the breakthrough curve very
well and k
d be integrated into the WJ equation. The values of k
v
are proportional to the values of flow rates and k
d, but independent of that of temperatures and xenon concentrations. 相似文献
2.
Thermal decomposition kinetics of magnesite were investigated using non-isothermal TG-DSC technique at heating rate (β) of
15, 20, 25, 35, and 40 K min−1. The method combined Friedman equation and Kissinger equation was applied to calculate the E and lgA values. A new multiple rate iso-temperature method was used to determine the magnesite thermal decomposition mechanism function,
based on the assumption of a series of mechanism functions. The mechanism corresponding to this value of F(a), which with high correlation coefficient (r-squared value) of linear regression analysis and the slope was equal to −1.000, was selected. And the Malek method was also
used to further study the magnesite decomposition kinetics. The research results showed that the decomposition of magnesite
was controlled by three-dimension diffusion; mechanism function was the anti-Jander equation, the apparent activation energy
(E), and the pre-exponential term (A) were 156.12 kJ mol−1 and 105.61 s−1, respectively. The kinetic equation was
\frac\textda\textdT = \frac105. 6 1 bexp( - \frac18777.9T ){ \frac32(1 + a)2/3 [(1 + a)1/3 - 1] - 1 }, \frac{{{\text{d}}\alpha }}{{{\text{d}}T}} = \frac{{10^{5. 6 1} }}{\beta }\exp \left( { - \frac{18777.9}{T}} \right)\left\{ {\frac{3}{2}(1 + \alpha )^{2/3} [(1 + \alpha )^{1/3} - 1]^{ - 1} } \right\}, 相似文献
3.
A new approach for determining the activation energy of amorphous alloys is developed. Setting the second order differential
coefficient of heterogeneous reaction rate equation of non-isothermal heating as zero at extreme points of DSC curve, we obtain
the new correlation taking form:
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