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Hui
Chen and Huiying Zhan, Department of Chemistry, Northwest Normal
University, Lanzhou, 730070, PR China
Kun
Zhu, Department of Environmental Engineering, Lanzhou Railway University,
Lanzhou, 730070, PR China
Mei Jiang, Jianmei Yuan and Wenjun Zhou, Department
of Chemistry, Northwest Normal University, Lanzhou,
730070, PR China
Loess
soils topographically cover the vast land expanding from
central Asia to north China where oil fields are widely
exploited, and resulted in the severe petroleum
contamination to soils and water resources. To provide an
appropriate description of the transport of organic
pollutants in the environment, it is important to include
a kinetics description of sorption in the transport
process. In this paper, we studied the sorption kinetics
of phenanthrene
and naphthalene on natural loess soils and loess soils
modified with a
cation surfactant hexadecyltrimethylammonium (HDTMA)
bromide. Results indicate
that the sorption rate is faster
on loess
soils modified with a cation surfactant than on natural loess soils and
the sorption data of both
fitted the first order reaction
r = kC0
+ n. In this formula r is a rate, C0 is a initial concentration, k is a rate constant
and n is a parameter. The sorption rates on two kinds of
soils depended on initial concentration of
phenanthrene
and naphthalene. Sorption equilibrium of phenanthrene and naphthalene has been achieved
approximately within thirty minutes and within an hour and
thirty minutes at
298K-318K,
respectively. Film diffusion is controlling step for
sorption
rates in the sorption process of
phenanthrene
and naphthalene on
natural loess soils and loess soils modified with cationic
surfactant, which is related to molecule configuration of phenanthrene and naphthalene.
The
rate constant was shown to be negative correlation with the
temperature(T). Through altering environmental
temperature, the activation energy and preexponential
factor can be calculated. The activation
energy of phenanthrene and
naphthalene were -6.196kJ·mol-1 and -15.70 kJ·mol-1 , respectively. The preexponential factor were 2.170 and 4.528,
respectively. The research results could be used to
predict
the
sorption kinetics of phenanthrene and naphthalene on loess soils
and can help to understand the transport of petroleum
contaminants in the environment.
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