Sorption
Mechanisms of Organic Compounds by Carbonaceous
Materials: Site Energy Distribution Consideration
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Abstract
Sorption of naphthalene,
lindane, and atrazine on 10 kinds of carbonaceous
materials which included four kinds of graphene, three kinds of graphite,
two kinds of carbon nanotubes and one kind of mesoporous carbon was
investigated. The approximate sorption site energy distributions were
calculated based on Dubinin-Ashtakhov (DA) model. The average sorption
site energy and standard deviation of the site energy distribution
were deduced and applied to analyze the interaction between sorbents
and sorbates, and the sorption site heterogeneity. The introduction
of oxygen-containing functional groups to the sorbents caused a decrease
in their average sorption energy for the studied compounds. However,
relative to the decrease in average site energy, the reduction in
number of sorption sites as indicated by surface area more strongly
reduced their sorption capacity to the tested carbonaceous materials
based on the result of the linear regression analysis. Sorption site
heterogeneity of the sorbents decreased as their oxygen contents increased,
which is attributed to the better dispersion of the oxygen-containing
materials as indicated by their TEM images. The method proposed in
this study to quantify the average sorption site energy and heterogeneity
is helpful for a better understanding of the sorption mechanisms of
organic pollutants to carbonaceous materials