United States
Environmental Protection
Agency
Ecosystems Research Division
National Exposure Research Laboratory
Athens, GA 30605
Research and Development
EPA/600/S-99/005
April 2000
&EPA ENVIRONMENTAL
RESEARCH BRIEF
Modeling Soil-Water Distribution of Aromatic Amines
In Water Saturated Soil Systems
Linda S. Lee1, Chad T. Jafvert2, Hui Li1, and Jose R, Fabrega-Duque2
Introduction
Organic bases such as aniline and aniline derivatives are
important environmental contaminants because of their high
potential toxicity and carcinogenicity, and the large mass
produced each year (Schnell et al., 1989). These organic
bases are employed as starting materials in the industrial
manufacturing of synthetic chemicals such as dyes,
pesticides, varnishes and perfumes (Schnell et al., 1989;
Essington, ME., 1994). Anilines are also found in wastes
from coal gasification and shale oil extraction processes,
and as microbial degradation products in soils treated with
phenylamide herbicides (Zachara et al., 1984; Kaufman,
1974). Despite their significance as environmental
pollutants, development of comprehensive quantitative
relationships for describing their sorption to natural sorbents
similar to those that have been developed for nonpolar
organic chemicals (NOCs) have been delayed due to their
intrinsic reactivity and ionogenic nature (see Lyman et al.,
1990 for NOC relationships). Indeed, predictive models for
sorption of organic bases are more complex because
simultaneous physical and chemical reactions of the cationic
and neutral species must be considered.
1 Dept. of Agronomy, Purdue University, West Lafayette, IN 47907
2 School of Civil Engineering, Purdue University, West Lafayette, IN 47907
Research summarized in this report focuses on the abiotic
interactions of aromatic amines with whole soils in aqueous
systems. This work was initiated to improve our ability to
predict the mobility of aromatic amines and their potential
to contaminate groundwater, and to improve subsequent
remediation of contaminated sites. Our work has focused
on identifying and quantifying, through process algorithms
and coefficients, some of the important chemical and
physical-chemical interactions that occur between aromatic
amines and soil constituents. In turn, process coefficients
are correlated to easily measured soil and solute properties.
Studies were conducted with seven aromatic amines (mostly
with aniline and oc-naphthylamine) and five surface soils.
The results of this work show that interaction of aromatic
amines with soils over short time periods (< 24 h) can be
adequately predicted on a macro-scale assuming cation
exchange as the primary mechanism, utilizing the pKa of the
amine, soil cation exchange capacity, and soil-solution pH.
For longer interaction times, aromatic amines undergo
irreversible binding and transformation reactions. The rates,
types, and extent of irreversible processes can be predicted
using available intrinsic solute reactiviy indices, assuming
only a minor dependence on specific soil properties with
regards to rate and type of reaction.
Printed on Recycled Paper
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Figure 1. Conceptual schematic of the interactions of aromatic amines with soils. SOM refers to soil organic matter and
italic numbers are defined in text
Background
Aromatic amines interact with soils through both reversible
and irreversible processes including: (;) exchange of the
organic cation with inorganic cations on clay and soil
organic matter (SOM) sites; (//) hydrophobic interactions of
the neutral organic base with SOM; (Hi) covalent bonding
with functional groups on SOM; and (iv) mineral-catalyzed
transformation reactions (Figure 1). The individual
contribution to sorption of each mechanism is dependent on
the speciation of the amine as controlled by the pH-pKa
relationship, and the available soil domains (e.g., cation
exchange sites and soil organic matter).
Cation exchange reactions are defined as the replacement of
one adsorbed, readily-exchangeable cation by another
(Sposito, 1989). Cation-exchange of organic bases is
impacted by speciation as controlled by pH-pKa
relationships. As speciation of an organic base shifts
towards the protonated form with decreasing pH, the
contribution of cation exchange to the overall sorption
process increases. Exchange of an organic cation is also
impacted by the composition and concentration of other
cations (Ainsworth et al., 1987; Brownawell, et al., 1990;
Kosson and Byrne, 1995). Organic cations (BH1) tend to
have a higher affinity for CEC sites than inorganic cations
of the same charge; however, as the concentration of the
inorganic cation is increased, sorption of the organic cation
will be decreased because of mass action laws governing
exchange (Lee et al., 1997; Zachara et al., 1987). Among
aromatic organic cations, selectivity for exchange sites
increases with the number of fused rings; therefore, larger
organic bases will depress sorption of smaller bases of
similar structure (Zachara et al., 1987; 1990; Lee et al
1997).
As contact time increases, aromatic amines continue to be
removed from the solution phase abiotically, primarily
through irreversible processes such as covalent binding with
particular constituents in soil organic matter (e.g., quinone
and phenolic functional groups), and mineral-catalyzed
transformation reactions. The use of quinones as a model to
investigate potential reactive sites in SOM showed evidence
of two reaction mechanisms: (1) the rapid but reversible
addition of the amino group to the C=O group of quinone to
form an imine; and (2) the slow but irreversible addition of
the amino group to a C=C bond in the aromatic ring of
quinone by 1,4-nucleophilic addition to produce
aminobenzenquinone (Parris, 1980; Bollag et al., 1983;
Ononye et al., 1994). Direct spectroscopic evidence exists
for similar reactions with humic substances along with the
further incorporation of aminobenzenquuione into nitrogen
heterocyclic linkages (Thorn, 1996a). Nucleophilic addition
is expected to accelerate with increasing pH for aromatic
amines due to the concomitant increase in the fraction of
neutral species. Weber et al. (1996) observed increasing
covalent binding rates of aniline to Suwannee River fulvic
acid with increasing pH. Iron and manganese oxides,
montmorillonite clays, and biological enzymes may catalyze
transformation reactions of aromatic amines such as
oxidative coupling, resulting in dimerization (Laha and
Luthy, 1990; Klausen et al., 1997; Ainsworth et al., 1991;
Tatsumi, 1994; Thorn, 1996b). The amine dimers, in turn'
may be preferentially, but not necessarily irreversibly'
sorbed to soil particles. Laha and Luthy (1990) observed
increasing reaction rates with decreasing pH for oxidation
of aniline by 5-MnO2. The observed pH dependence was
hypothesized to result from the enhanced formation of
surface precursor complexes and not attributed to any pH-
dependent speciation of the amine. Clearly, the impact of
pH on the overall long-term reactivity of aromatic amines
with soils is complex. At low pH, both reactivity of the soil
surface and redox potential are generally increased;
however, speciation of the aromatic amine shifts away from
the neutral species, identified as the more reactive species
for both covalent binding and oxidative transformation.
-------
Table 1. Selected physical and chemical properties of aromatic amines used in this study.
Chemicals
p-Methoxyaniline (CH3O-AN)
a-Naphthyamine (NAPH)
p-Methylaniline (CH3-AN)
Aniline (AN)
p-Chloroaniline (Cl-AN)
p-Aminobenzoic Acid (COOH-AN)
p-Nitroaniline(NO3-AN)
S.Xg/L)1
21
1.7
7.4
3.4
10
3.4
0.8
logKow
0.953
2.252
1.412
0.902
1.832
0.682
1.393
pKa'
5.34
3.92
5.08
4.63
4.15
2.50;4.87
1.0
E1/2(V)4
0.393
ti.545
0.537
0.625
0.675
0.714
0.935
. g+6
-0.78
—
-0.31
0.00
0.11
0.42
0.79
1 Aqueous solubility (Sw) (Verschueren, 1996);2 CRC, 1982;3 Lyman, etal., 1982;" Suatoni etal., 1961;
5 Pysh and Yang, 1963; 6Laha and Luthy, 1990.
Table 2. Characterization data based on air-dried soils (<2 mm) for soils used in this study.
Soil
Toronto
Chalmers
Drummer
Bloomfield
Okoboji
PH
1:1 soilrwater
4.4
6.5
7.2
6.4
7.4
Sand
%
11.9
11.1
13.0
81.4
31.8
Silt
%
67.6
72.8
66.0
11.0
36.2
Clay
%
20.5
16.0
21.2
7.6
32.0
OC
%
1.34
1.17
2.91
0.36
4.98
CEC
cmol(_-/kg
11.2
13.0
26.5
4.4
36.2
Differentiating between reversible and irreversible
processes, and quantifying the parameters that control these
processes, are imperative in improving the assessment and
subsequent remediation of sites contaminated with aromatic
amines. The impact of irreversible versus reversible
processes will be a function of the residence time of the
aromatic amine in the soil, the availability of reactive sites
in SOM, and the type of mineral surfaces present As
aromatic amines are allowed to age within the soil matrix,
the formation of soil-bound residues will increase and
availability for further transport and/or microbial
degradation will diminish. The interactions of aromatic
amines with soil/sediment constituents or model compounds
have been studied for relatively short contact times;
however, results from long-term studies are sparse.
In the following sections, our experimental observations,
modeling approaches, and resulting quantitative
relationships are summarized for the interactions of
aromatic amines in saturated soil systems during short
periods in single and binary systems, and for long-term
interactions using single solute systems. Studies were
conducted with aniline, a-naphthylamine, five substituted
anilines, and two to five surface soils. Solute and soil
properties are summarized in Table 1 and Table 2,
respectively. Details can be found in several publications
listed in Appendices A and B.
Sorption During Short Characteristic Times
During short characteristic time periods (e.g., < 24 hours),
sorption of organic amines is primarily reversible. Cation-
exchange is the predominant sorption mechanism and soil-
solution pH is the most significant factor controlling the
magnitude of sorption in soil systems (Lee et al., 1997;
Zachara et al., 1986; Moreale and van Blandel, 1976). The
hypothesis that cation-exchange largely regulates loss to the
soils during a one-day incubation time can be tested for a
given electrolyte matrix using a simple model that assumes
all solute lost from solution is through distribution of the
protonated species to cation-exchange sites on the soil. The
concentration of the protonated species in solution (CBH+,
nmol BHVmL) can be estimated using eq 1,
CBH+=(--T
where CT (nmol/mL) refers to the total solution
concentration of amine (i.e., neutral and protonated species)
measured after a one-day equilibration, and f BH+ is the
fraction of base that exists as a cation hi solution. Sorbed
concentrations can be expressed in terms of the cation-
exchange capacity (CEC) of the soil [S*, nmol/ molH],
S = SI CEC
(2)
where S (jomol/ g) is the amount of amine lost per mass of
soil and CEC is expressed in mol(./g. This is analogous to
the KOO concept where the reactive domain for sorption of
nonpolar organic compounds is assumed to be soil organic
carbon (OC) so that normalization of sorption to OC (Soc -
S/OC) results in a single distribution plot (Lee et al., 1997).
Typical sorption isotherms and isotherms normalized with
respect to solution speciation and soil cation-exchange sites
(eqs 1 and 2) are illustrated for aniline hi Figure 2.
No'rmalization resulted hi compensation for most of the
differences originally observed in sorption by the various
soils from a given CaCl2 concentration. Similar results were
-------
obtained for a-naphthylamine. This lends support to the
hjpothesis that cation exchange and/or other similarly pH-
depcndent reactions account for most of the loss to these
soils during initial contact times.
1 -
-2-
AnMIne
SmMCaCLj
-3
-2-1
log[C(umd/mL)]
2'
Aniline
SmMCaCI,
• Toronto * Drummer
n Chalmers • Otobq'i
• Bloomfield
A -Toronto pH~29
O -Toronto pH-5.8
*pH adjusted
Figure 2.
-4-3-2-1
log (CBH* (tutwl BH'VmL)]
Aniline sorption to several soils at their natural soil-solution
pH and pH-adjusted Toronto soil from 5 mM CaCl2
solutions: (A) measured distribution; and (B) charge-
normalized distribution plots.
Sorption of aniline and a-naphthylamine was measured from
single organic solute solutions containing 0.5, 5, or 50 mM
CaCl2 concentrations. For aniline, a decrease in sorption
with increasing CaCk concentration was significant only for
Toronto soil where BH^was abundant in the aqueous-phase.
Competition between Ca24" and BH1" for CEC sites would
result in decreasing amounts of BH1" sorbed with increasing
additions of Ca2* consistent with a cation-exchange process.
However, increasing the CaCk concentration also resulted in
decreases in soil-solution pH by displacement of H1" from the
soil, thereby increasing fBn+ and the amount of amine
available for cation-exchange. The net result was a reduced
impact of Ca2+ additions on the sorption of aniline.
A two site (TS) and a distributed parameter (DP) model
were developed to describe the primary processes affecting
aromatic amine sorption for short contact time. Mass action
equations considered in both models were: a) acid
dissociation of the protonated organic base (eq 3); b)
sorption of the neutral species to soil organic carbon
through the partition coefficient KOC (eq 4); and c) ion-
exchange of the protonated organic base (BH1) and
inorganic divalent cations (D2+ = Ca2'1'+ Mg24) (eqs 5, 6),
pan
: focKoc =
[B]
[BHS]
KD=-
[D0.5S]
2+05
[S-]P2+]
(3)
(4)
(5)
(6)
where Ka is the acid dissociation constant of the conjugate
acid (mol/L), B represents the neutral aqueous organic base
(mol/L), KOC represents the partition coefficient to soil
organic carbon (L/kg), f^ is the fraction of organic carbon,
Bs represents the concentration of B associated with the soil
(mol/kg), D2+ represents the sum of divalent inorganic
cations (Ca2+ + Mg24) (mol/L), BHS and D0.5S are the
organic and inorganic cations, respectively, that are attached
to cation exchange sites in the soil (S"), KBH and KD are
association constants for BIT1" and D24, respectively, and are
related to a third constant, KO by the following expression,
_KBH
[BHS][D2+]05
KD [BH+][D0.5S]
(7)
KQ (MT05) is the selectivity coefficient employing the
Gapon cation exchange convention (Gapon, 1933). In the
TS Model, cation exchange was accounted for by a single
cation exchange coefficient (Ka) that is solute dependent.
While this model is conceptually simple, accounting for
mass transfer to two types of sites, neutral organic carbon
sites and cation exhange sites, it fails to capture much of the
nonlinearity observed in the distribution isotherms.
Nonlinearity is likely due to the chemical heterogeneity of
cation exchange sites. In the DP model, all sites are not
assumed to have identical affinities for a given organic
cation (BH4). Site affinities are assumed to have a
distribution of affinities, which serves as a better
representation of the chemical heterogeneity of cation
exchange sites on soils. The frequency distribution of sites
is represented with a Gaussian probability distribution
function on log KBHii with mode (a. and standard deviation CT
(Fernandez and Steel, 1998):
(8)
Mathematically, eqs 5 and 6 are employed in the model with
organic and inorganic cations being associated with
unoccupied cation exchange sites (S") assuming the
following mass balances:
BHS =
i=n
(9)
1=1
i=\
-------
i=n
-£
1=1
i=n
5Z
1=1
do)
In this way, the overall model conveniently is expressed as a
system of two nonlinear equations with two unknown
values (BH* and D2+) (Fabrega et al., 1998).
The DP model was evaluated using aniline and
-------
Both the TS and the DP model were assessed for predicting
competitive sorption in binary organic solute systems
(Fabrega, 1999). Predictions from the TS model were poor.
The TS model is a general mass action model that does not
consider the site heterogeneity of cation exchange sites,
unlike the DP model. As indicated previously in the DP
model, cation exchange is modeled as three independent
processes involving vacant sites (S~) (Figure 5) with a
bivariate normal density function (Ang and Tang, 1975)
utilized to establish a correlation between the set of log
KBH.I values unique for each aromatic amine. Examples of
data and model results are shown for sorption of aniline and
a-naphthylarnine by Toronto soil in 5 mM CaCl2 solution at
pH=2.70 and pH=5.78 in Figure 6. For the binary solute
isotherms, initial amine concentrations were in equal molar
ratios. In all cases, die DP model successfully predicted the
lack of competition by aniline for a-naphthylamine and the
suppression in aniline sorption by a-naphthylamine.
KBH
'f BHS/+
T
/S7
'f*J,.
'K.
'K, t
2[B]
aq
Figure 5. DP model where sorption of the neutral species is
predicted from K^, and cation exchange is modeled
as three independent processes involving vacant
sites (S~) where superscripts 1 and 2 specify the two
different aromatic amines.
Long-Term Sorption and Transformation
Reactions
The abiotic interaction of aniline, a-naphthylamine, and five
substituted anilines (Table 1) with two to five surface soils
(Table 2) was investigated in sterilized systems. Solute
concentrations were determined m,both the aqueous and
solid phases at various times throughout a two-month
equilibration period. Solute extracted using a rigorous
extraction method was considered to be reversibly sorbed.
Solute mass not recovered was assumed to be irreversibly
bound or transformed. The relative contributions from the
different processes varied across soils and between solutes;
however, the general dissipation was similar to what is
shown for aniline with the Okoboji soil in Figure 7.
DP Model
Toronto Soil - pH = 5.78
D Aniline
A Naphthylamine
• Aniline-binaxy
A Naphthylamine-Biximy
0.20 0.40 0.60 0.80 1.00
DP Model
Toronto Soil - pH = 2.70
a Aniline
A Naphthylamtne
• Aniline-binary
A Naphlhylamine-Binary
0.40 0.60 0.80
C (mmol / L)
Figure 6. Single and binary (aniline and a-naphthylamine)
isotherms for Toronto soil measured in a 5 mM
CaCl2 solution with pH values of 5.78 and 2.70. Solid
lines are competitive DP model predictions. Values
for |i and a obtained from single solute data
£
-Q
I
T
p8
400 6X
Time (h)
Figure 7.
Percent distribution of aniline (in the aqueous
phase; reversibly-sorbed; and irreversibly-bound
or transformed) relative to the total aniline
applied as a function of time with Okoboji soil.
-------
40 -
30 •
20 -
1 0 -
0 -
1.4 -
1 .2 •
1.0 •
0.8 -
0.6 -
0.4 -
0.2
0.0 •
X"
f
A^W "*" * "*" * * * *
,:..»
1°** -»% ° =
SB ° ° ° «
5^ 0° 00 o 0 °
- p-m eth oxya n ilin e
• a-n a p h th yla m in e
•» p-m eth yla n ilin e
^ an ilin e
•» p-ch lo ro an ilin e
• . p -a m in o b e n z o n ic acid
o p -n itro aniline
0 200 400 600 800 1000
„» •*• ™ ""
•* • ™
•i™
200
400
600
800 1000
Time (hour)
1200
1400
1600
Figure 8. Irreversible binding and/or transformation of several amines (S^) in Okoboji soil with time.
Initially, most of the sorption appears to be fast and
reversible, while slow chemical binding/transformation
becomes increasingly more significant over time. The
extractable soil-sorbed concentrations and corresponding
aqueous concentrations measured at each sampling time
over the two-month equilibration are in good agreement
with the 24-h, nonlinear sorption isotherms indicating fast
desorption of reversibly-sorbed solute as the aqueous-phase
concentrations are depleted by the slower, irreversible
processes (Li and Lee, 1998).
Other distribution experiments were conducted with the
same initial amine concentration but at soil mass to solution
ratios (m/V) varying over a factor of tea Reversible
sorption processes were not impacted over the m/V range
investigated; however, the irreversible loss of amine
((imol/kg) increased with decreasing m/V. Fast, reversible
sorption processes reduced aromatic amine concentrations
in solution and retarded irreversible reactions indicating the
concentration-dependence of the latter. With irreversible
and reversible processes occurring in parallel, parameters
from the reversible sorption isotherms can be used to predict
amine solution concentrations available for irreversible
binding and transformation.
The specific irreversible sorption/transformation process as
well as the rate and extent of the reaction varied
significantly among the aromatic amines. Figure 8
exemplifies the trends observed across solutes on a given
soil for the amount of amine irreversibly bound or
transformed (Sur). The rate and extent of irreversible loss
correlated very well to the intrinsic reactivity of the
aromatic amine, which is reflected in the reported Hammett
constants (S4) and half-wave potentials (Ei/z) (Pysh and
Yang, 1963). Intrinsic solute reactivity increases with
decreasing 5+and E]/2. For p-methoxyaniline, which has the
lowest 5+ and EI/Z values, more than 85% of the amine was
irreversibly lost during the 2-month equilibration whereas
less than 12% of p-nitroaniline, with the largest 8+ and E1/2
values, was irreversibly lost on any soil.
Our ability to accurately define the magnitude and rate of
each process contributing to irreversible binding and
transformation in whole soils would result in a model with
several unknown variables. Therefore, a simple
heterogeneous reaction model commonly used to describe
gas reaction kinetics on heterogeneous solid surfaces was
modified to estimate reaction rates based on a few
assumptions hypothesized to be valid for interactions of
aromatic amines with whole soils. We assumed that (/') all
irreversible binding and transformation reactions are first-
order with respect to the aromatic amine solution
concentration; (//') activation energies vary linearly as a
function of reactive sites; and (i/7) available reactive soil
sites change over time but remain more numerous than sites
consumed. A similar approach has been used in describing
the reaction kinetics of gas on heterogeneous solid surfaces
(Low, 1960) and nutrient sorption/desorption (Aharoni, et
al, 1991). The observed change in reaction rates with time
was best described using a biphasic approach where
reaction rates were estimated independently for contact
times < 20 h and > 20 h. The initial rate of the irreversible
reaction was faster by a factor of 20 than the rate at later
times. Rates are expected to retard with time because the
probability of collisions with sufficient energy to activate a
reaction will decline as solute molecules are depleted and
remaining reactive sites have increasingly higher energies of
activation. For the various amines, apparent rate constants
(kapp) vary approximately one to two orders-of-magnitude,
but for a given solute, kapp values across soils varied less
than a factor of four. Therefore, as a first assessment of
trends between amines, apparent rate constants were
averaged across soils. With the exception COOH-AN,
apparent reaction rates for both operationally defined time
periods generally decrease in a natural log-linear manner
-------
with decreasing solute reactivity as represented by intrinsic
reactivity indices 8f and EI/Z (Figure 9) as observed for other
systems (Laha and Luthy, 1990). Compared to the other
anilinium compounds, reaction rates with COOH-AN were
almost two orders-of-magnitude faster than expected from
the reported intrinsic reactivity indices, which may be due
to the presence of the strong electron-donating carboxylic
acid group.
N02-AN
•0.3 0.0
HammMt Constant (S4)
B
CHjOAN
KAPH
TCHj-M)
0£ O.C 0.7 0.8 OJ
Half Wave Oxlditlon Potential (V)
Figure 9. Average apparent reaction rates (kvp, h"1) of
irreversible process for several aromatic amines
correlated to (A) Hammctt constant; and (B) Half-
Wave Oxidation Potential, during two
characteristic time periods of < 20 h and > 20 h.
During the course of the long-term study, pink-red colored
substances appeared in the soil phases that had been spiked
with either p-methoxyanline, oc-naphthylamine, or p-
mcthylaniline. The colored substances were not observed in
the aqueous-phase. The colored substances were extractable
with an acetonitrile/acetate buffer indicating that not all of
tire irrevesible reactions resulted in covalent bonding to the
soil phase, but rather transformation to products that are
strongly sorbed to the soil phase. With increasing contact
times between the aqueous amine solution and the soil, the
red hue in the solvent extracts of the soils became more
pronounced. Multiple peaks were observed in the GC-MS
analysis of the solvent extracts from the p-methoxyaniline
spiked soils with the primary derivative identified as 4,4'-
dimethoxyazobenzene. For the soil with a-naphthyl-amine,
the dominant derivative identified was N-(l-
aminonaphthyl)-l-naphthylamine while for p-methylaniline
spiked soils, the apparent derivative concentrations were
below the detection limits of the GC/MS employed.
Evidence of dimer formation for at least p-methoxyaniline
and a-naphthylamine is indicative of soil-catalyzed radical
formation and coupling reactions as has been shown with
Fe(IH) and Mn (TV/HI) oxides, montmorillonite clays, and
biological enzymes (Laha and Luthy, 1990; Klausen et al.,
1997; Ainsworth et al., 1991; Tatsumi, 1994). Not all
amines may undergo oxidative coupling. For the amine/soil
combinations investigated hi this study, transformation
reactions were only evident for amines with Ei/2< 0.54 V.
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octanol. Environmental Toxicology and Chemistry, 17:
369-376.
(5) Strathmann, T. 1997. Ion-pan- association of
substituted phenolates with K+ in octanol. M.S. thesis,
Purdue University, West Lafayette, IN.
(6) Li, H. and L.S. Lee, 1999. Sorption and abiotic
transformation of aniline and 1-naphthylamine by
surface soils. Environmental Science & Technology,
33:1864-1870.
(7) Fabrega, J. 1999. Modeling Distribution of Aromatic
Amines in Saturated Aqueous Systems. Ph.D.
dissertation, Purdue University, West Lafayette, IN.
(8) Li, Hui. 1999. Sorption and Transformation of
Aromatic Amines by Surface Soils in Aqueous
Systems. Ph.D. dissertation, Purdue University, West
Lafayette, IN.
(9) Fabrega, J., C.T. Jafvert, H. Li, L.S. Lee, 2000.
Modeling long-term abiotic processes of aniline to
water-saturated soils. Environmental Science &
Technology, Accepted.
Appendix B (Works Submitted or in Progress)
(1) Li, H., Lee, L.S., Fabrega, I, Jafvert, C., Graveel, J.,
2000. Effect of substitution on the interaction of
aromatic amines with soils in aqueous systems.
Environmental Science & Technology, (submitted).
(2) Fabrega, J., C.T. Jafvert, H. Li, and L.S. Lee. 2000.
Modeling competitive sorption of aniline and 1-
naphthylamhie by water-saturated soils, (to be submitted
to Environmental Science & Technology).
(3) Li, H., L.S. Lee^ Fabrega, I, and C.T. Jafvert. 2000.
Single and binary sorption of aromatic amines on
surface soils (to be submitted to Chemosphere).
Appendix A (Published Papers)
(1) Fabrega, I, C.T. Jafvert, H. Li, L.S. Lee, 1998.
Modeling short-term soil-water phase distribution of
aromatic amines. Environmental Science and
Technology, 32:2788-2794.
(2) Lee, L.S., A. K. Nyman, H. Li, M.C. Nyman, and C.
Jafvert. 1997. Initial sorption of aromatic amines by
surface soils. Environmental Toxicology and Chemistry,
16:1575-1582.
(3) Nyman, M.C., A. Nyman, L.S. Lee, L. Nies and E.
Blatchley. 1997. Fate of 3,3'-dichlorobenzidine in lake
systems. Environmental Science and Technology,
31:1068-1073.
(4) Strathmann, T. and C. T. Jafvert. 1998. Ion-pair
association of substituted phenolates with K+ in
Disclaimer
The information in this document has been funded wholly
or in part by the United States Environmental Protection
Agency under cooperative agreement CR-823581 with
Purdue University. This document has been subjected to
the Agency's peer and administrative review and has been
approved for publication as an EPA document
Quality Assurance Statement
All research projects making conclusions or
recommendations based on environmentally related-
measurements and funded by the Environmental Protection
Agency are required to participate in the Agency Quality
Assurance (QA) program. This project was conducted
under an approved QA project plan. Information on the
plan and documentation of the QA activities are available
from the Principal Investigators (L.S. Lee and C.T. Jafvert).
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