Page 402 - Environmental Nanotechnology Applications and Impacts of Nanomaterials

Nanomaterials as Adsorbents 385

TABLE 10.3 DED Model Parameters for Naphthalene and 1,2-
Dichlorobenzene Adsorption and Desorption with nC 60 (Cheng
et al., 2005)
a 1st a 2nd a 2nd 2
Sorbate Log K d (ml/g) Log K d (ml/g) Log q max ( g/g) R
Naphthalene 3.75!0.01 5.9!0.04 3.91!0.01 0.996
1,2-DCB 3.48!0.01 5.68!0.08 3.98!0.03 0.977
a 1st
adsorption data used to determine K d from first term in Eq. 6. Desorption
1st 2nd 2nd
data and K d determined from adsorption data used to find K d and q max by
fitting the data to Eq. 6.

4.28!0.04 0.45!0.05 3.7!0.01
10 C w ), and a linear isotherm (K 10 C ) were used
d
to fit the data of the C large aggregates, small aggregates, and the nC 60
60
forms, respectively. The data suggest that adsorption of naphthalene to
nC is similar to other forms of carbon. Desorption of the naphthalene
60
from the nC 60 was highly hysterertic. The K value for desorption
d
increased by about two orders of magnitude higher than the correspon-
ding adsorption value. These data were fitted with a two-compartment
desorption model (Kan et al., 1998) (Figure 10.5 and Table 10.3).
Adsorption and desorption experiments were also performed with 1,2-
dichlorobenzene to nC . The adsorption and desorption data were fitted
60
with a linear isotherm (q 10 3.48!0.01 C ) and with the two-compartment
w
desorption model, respectively (Table 10.2).
The experimental data show that 1,2-dichlorobenzene and naphtha-
lene adsorption and desorption with nC 60 are similar. The different
sizes of the C 60 aggregates affect the adsorption of naphthalene by
orders of magnitude. The desorption of the environmental contami-
nants from nC exhibits hysteresis. Kinetic data also showed that des-
60
orption of naphthalene from C 60 aggregates is composed of two
compartments: a labile compartment, where naphthalene is probably
adsorbed on the outside surface and can readily be desorbed, and a
resistant desorption compartment, where naphthalene may be
entrapped either in the C 60 aggregates or in the surface crevices and
desorption is hindered.
There is great potential for the use of inorganic nanoparticles, such
as TiO , carbon or metallic nanoparticles (see Chapters 5 and 8), for
2
the treatment of organic pollutants in water treatment and the
environment. These nanoparticles have several advantages over the
current microparticles used, such as high surface areas, higher affin-
ity and surface reactivity, faster degradation rates, photocatalytic
abilities, lower cost, and higher efficiency. With more fundamental
research and development of technological applications, these inor-
ganic nanoparticles have the ability to be used for environmental
applications.