Environmental chemistry of phosphonates

ARTICLE IN PRESS
Water Research ] (]]]]) ]]]–]]]
Review
Environmental chemistry of phosphonates
Bernd Nowack*
Institute of Terrestrial Ecology (IT
.
O), Swiss Federal Institute of Technology Z
.
urich (ETH), Grabenstrasse 3,
CH-Schlieren 8952, Switzerland
Received 16 August 2002; received in revised form 21 January 2003; accepted 31 January 2003
Abstract
Phosphonates are anthropogenic complexing agents containing one or more C–PO(OH)
2
groups. They are used in
numerous technical and industrial applications as chelating agents and scale inhibitors. Phosphonates have properties
that differentiate them from other chelating agents and that greatly affect their environmental behavior. Phosphonates
have a very strong interaction with surfaces, which results in a significant removal in technical and natural systems. Due
to this strong adsorption, little or no remobilization of metals is expected. No biodegradation of phosphonates during
water treatment is observed but photodegradation of the Fe(III)-complexes is rapid. Aminopolyphosphonates are also
rapidly oxidized in the presence of Mn(II) and oxygen and stable breakdown products are formed that have been
detected in wastewater. The lack of information about phosphonates in the environment is linked to analytical
problems of their determination at trace concentrations in natural waters. Further method development is urgently
needed in this area, including speciation of these compounds. With the current knowledge on speciation, we can
conclude that phosphonates are mainly present as Ca and Mg-complexes in natural waters and therefore do not affect
metal speciation or transport.
r 2003 Elsevier Science Ltd. All rights reserved.
Keywords: Phosphonates; Chelating agents; Adsorption; Heavy metals; Degradation; Speciation
Contents
1. Introduction . . . . . . . . 2

2. Properties . . . . . . . . . . 2
3. Analysis of phosphonates . . 4
3.1. Analytical methods . . . . . . . 4
3.2. Concentrations in the environment . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Surface reactions . . . . . . 5
4.1. Adsorption . . . . . . . . . . . 5
4.2. Dissolution of minerals . . . . . 6
4.3. Remobilization of metals . . . . 6
4.4. Precipitation . . . . . . . . . . 7
4.5. Inhibition of dissolution and precipitation . . . . . . . . . . . . . . . . . . . . 7
*Tel.: +41-1-633-61-60; fax: +41-1-633-11-23.
E-mail address: (B. Nowack).
0043-1354/03/$ - see front matter r 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0043-1354(03)00079-4
1. Introduction
Phosphonic acids, compounds containing the Lewis
acid moiety R-CP(O)(OH)
2
, are characterized by a
stable, covalent carbon to phosphorous bond. The
corresponding anions of the phosphonic acids are called
phosphonates. The most commonly used phosphonates
are structural analogues to the well-known aminopoly-
carboxylates such as ethylenediaminetetra acetate
(EDTA) and nitrilotriacetate (NTA). The environmental
fate of these aminopolycarboxylate chelating agents has
received considerable attention [1–5]. Much less is
known about the fate and behavior of the corresponding
phosphonates in the environment [4,6,7]. The existing
reviews are either several years old and therefore do not

cover the newest literature [6] or focus on toxicology and
risk assessment based on the limited data that were
available at that time [7]. What is missing is an overview
of the chemistry of these compounds which can help us
to understand and predict the environmental behavior
of these compounds more accurately and that can be the
basis for a refined risk assessment. The aim of this
review is therefore to provide an overview of the current
knowledge of the environmental chemistry of phospho-
nates. It concentrates on polyphosphonates, compounds
containing more than one phosphonic acid group, and
especially aminopolyphosphonates, compounds contain-
ing several phosphonate and one or more amine groups.
Glyphosate, a herbicide containing a phosphonate, a
carboxylate and an amine functional group, is not
discussed in detail in this review. There is, however,
much information available about the environmental
chemistry and behavior of this compound [8–10].
This review starts with a short description of the
properties of phosphonates and their analysis. Phos-
phonates have a very strong interaction with surfaces
and the section discussing the surface reaction follows:
adsorption, dissolution of minerals, remobilization of
metals, precipitation of phosphonates and inhibition of
precipitation of minerals are covered. In the degradation
section biodegradation, photodegradation, chemical
degradation and degradation during oxidation processes
are discussed. The speciation of phosphonates in the
environment covers the next section, which is followed
by a discussion of their environmental behavior. This

section contains a summary of the data on measured
concentrations of phosphonates and their behavior
during wastewater treatment.
2. Properties
Table 1 lists the abbreviations, names and structures
of the phosphonates discussed in this review. These
compounds are known under many different abbrevia-
tions that vary between the disciplines and countries and
have changed with time. Phosphonates are effective
chelating agents according to the IUPAC definition that
chelation involves coordination of more than one sigma-
electron pair donor group from the same ligand to the
same central atom. Phosphonates are used as chelating
agents in many applications, e.g. in pulp, paper and
textile industry to complex heavy metals in chlorine-free
bleaching solutions that could inactivate the peroxide. In
medicine phosphonates are used to chelate radionuclides
for bone cancer treatments [11].
A recent IUPAC Technical Report [12] critically
evaluates the available experimental data on stability
constants of proton and metal complexes for phospho-
nic acids. It presents high-quality data as ‘‘recom-
mended’’ or ‘‘provisional’’ constants while for
example, all constants for DTPMP have been rejected
due to insufficient purity of the parent compound. This
report will be of great use for all future speciation
calculations and should be the sole source of stability
constants when ever possible.
The stability of the metal complexes increases with
increasing number of phosphonic acid groups. Fig. 1

shows that the monophosphonate aminomethylpho-
sphonic acid (AMPA) has the lowest stability constants
ARTICLE IN PRESS
5. Degradation . . . . . . . . 7
5.1. Biodegradation . . . . . . . . . 7
5.2. Photodegradation . . . . . . . . 8
5.3. Chemical degradation . . . . . 8
5.4. Degradation during oxidation processes . . . . . . . . . . . . . . . . . . . . . 9
6. Speciation . . . . . . . . . . 9
7. Behavior during wastewater treatment . . . . . . . . . . . . . . . . . . . . 10
8. Conclusions . . . . . . . . . 11
Acknowledgements . . . . . . . 11
References . . . . . . . . . . . . 11
B. Nowack / Water Research ] (]]]]) ]]]–]]]2
ARTICLE IN PRESS
Table 1
Abbreviations, names, and structures of the phosphonates covered in this review
Abbreviation Other abbreviations also in use Name Structure
HEDP HEDPA, HEBP 1-Hydroxyethane(1,1-diylbisphosphonic acid)
C
PO(OH)
2
H
3
COH
PO(OH)
2
NTMP ATMP, NTP, NTPH, NTPO Nitrilotris(methylenephosphonic acid)
N
(HO)

2
OP
(HO)
2
OP PO(OH)
2
EDTMP EDTP, EDTPH, ENTMP, EDTMPO, EDTMPA 1,2-Diaminoethanetetrakis (methylenephosphonic acid)
N
NPO(OH)
2
PO(OH)
2
(HO)
2
OP
(HO)
2
OP
DTPMP DETPMP, DTPPH, DETPMPA, DETPMPO Diethylenetriaminepentakis (methylenephosphonic acid)
N
N
(HO)
2
OP
(HO)
2
OP N PO(OH)
2
PO(OH)
2

PO(OH)
2
PBTC PBTCA Phosphonobutane-tricarboxylic acid
C
COOH
PO(OH)
2
HOOC
COOH
B. Nowack / Water Research ] (]]]]) ]]]–]]] 3
and EDTMP with 4 phosphonic aid groups the highest.
The log K values of the different transition metal
complexes follow the Irving–Williams series Mn
2+
o-
Fe
2+
oCo
2+
oNi
2+
oCu
2+
>Zn
2+
.
Fig. 2 shows a speciation diagram for the system Zn-
EDTMP calculated with the constants from [12] with the
speciation program ChemEQL [13]. This calculation
shows that in the pH range found in technical

applications and in natural waters a large number of
possible complexes with different degree of protonation
and charge exist. At pH 6 the species H
4
EDTMP
4À
,
ZnH
3
EDTMP
3À
, ZnH
2
EDTMP
4À
and ZnHEDTMP
5À
occur at a percentage of more than 5% of total
EDTMP. Complexation of other metals by other
phosphonates is similar and at each pH value several
species coexist.
Phosphonates are not only chelating agents but also
very potent inhibitors of mineral precipitation and
growth. This effect works at concentrations well below
the amount needed to chelate all metals. An important
industrial use of phosphonates is in cooling waters,
desalination systems and in oil fields to inhibit scale
formation, e.g. barium sulfate or calcium carbonate
precipitation. Phosphonates are also used in medicine to
treat various bone and calcium metabolism diseases [14].

In detergents phosphonates are used as a combination of
chelating agent, scale inhibitor and bleach stabilizer [15].
Phosphonates are highly water-soluble while the
phosphonic acids are only sparingly soluble. Phospho-
nates are not volatile and poorly soluble in organic
solvents. More detailed data on the physico-
chemical properties of the phosphonates can be found
in reference [7].
The consumption of phosphonates was 56,000 tons
worldwide in 1998 [16] and 16,000 tons in Europe in
1999 [4]. Data about the distribution among the various
phosphonates are available for Europe and the US [6],
for the Netherlands [7] and for Germany [4]. HEDP and
DTPMP are the most important phosphonates based on
the used volumes.
The toxicity of phosphonates to aquatic organisms is
low [6,7,17]. Reported values for 48 h LC50 values for
fish are between 0.1 and 1.1 mM [18,19]. Also the
bioconcentration factor for fish is very low [20,21].
Phosphonates are poorly absorbed in the gastro-
intestinal tract and most of the absorbed dose was
rapidly excreted by the kidneys [22]. Human toxicity is
also low which can be seen in the fact that phosphonates
are used to treat various diseases [14,23].
3. Analysis of phosphonates
3.1. Analytical methods
The absence of a reliable trace analytical method for
phosphonates results in a lack of detailed information
about the environmental behavior of phosphonates.
Most of the current methods for phosphonate determi-

nation have detection limits above the expected natural
concentrations or suffer from interferences in natural
samples.
The standard method for the determination of
phosphonates is ion-chromatography followed by post-
column reaction with Fe(III) and detection of the
Fe(III)-complexes at 300–330 nm [24–26]. This method
has a detection limit of about 2–10 mM. Other methods
have been developed based on post-column oxidation of
the phosphonate to phosphate and detection of phos-
phate with the molybdenum blue method [27]. Ion-
chromatography with pulsed amperometric detection of
amine-containing phosphonates [28], ion-chromatogra-
phy with indirect photometric detection [29] and
capillary electrophoresis with indirect photometric
detection have also been described [30]. These methods
all have high detection limits of 1 mM or more and are
therefore not suitable for natural systems.
A very powerful method is the derivatization of
the phosphonic acid group with diazomethane and
ARTICLE IN PRESS
0
2 10
-7
4 10
-7
6 10
-7
8 10
-7

1 10
-6
2 4 6 8 10 12
concentration (M)
pH
H
5
EDTMP
3
-
H
6
EDTMP
2
-
ZnHEDTMP
5
-
HEDTMP
7
-
ZnH
2
EDTMP
4
-
ZnH
3
EDTMP
3

-
H
4
EDTMP
4
-
H
7
EDTMP
-
Fig. 2. Speciation of 1 mM EDTMP in the presence of 1 mM Zn.
The diagram has been calculated using the constants from [12].
0
5
10
15
20
Mn
2+
Fe
2+
Co
2+
Ni
2+
Cu
2+
Zn
2+
log K (M + HL)

EDTMP
NTMP
HEDP
AMPA
IDMP
Fig. 1. Stability constants of 1:1 complexes (M+HL) with
transition metals of AMPA, IDMP, HEDP, NTMP and
EDTMP (Irving–Williams series) with data from [12].
B. Nowack / Water Research ] (]]]]) ]]]–]]]4
separation and detection of the derivatives by HPLC-
MS [31]. This method is however, not applicable to
natural waters due to interference by the major cations
and anions of the water matrix. The only method with a
low enough detection limit in natural samples is an ion-
pair HPLC method with precolumn formation of the
Fe(III)-complexes [32]. The phosphonates can be
measured with a detection limit of 0.05 mM in natural
waters and wastewaters. The method, however, is not
able to quantify bisphosphonic acids such as HEDP at
low concentrations. This is a major drawback because
HEDP is one of the most used phosphonates [4,6].
The breakdown products of the Mn(II)-catalyzed
degradation of NTMP [33], iminodimethylenephospho-
nic acid (IDMP) and N-formyl-iminodimethylenephos-
phonic acid (FIDMP), can be detected after derivatization
of the aldehyde group in FIDMP by 2,4-dinitrophenylhy-
drazine and derivatization of the imine-group in IDMP by
9-fluorenyl methylchloroformate [34]. A detection limit of
0.01 mMFIDMPand0.02mM IDMP has been achieved.
Anion-exchange chromatography coupled to ICP-MS

is able is a very promising method for chelating agent
analysis [35,36]. The method is also applicable to
phosphonates and it has been shown that CuEDTMP
can be determined with a very low detection limit in the
nanomolar range.
Preconcentration of phosphonates from natural water
samples using different adsorbents has been tested [37].
It was found that the investigated phosphonates HEDP,
NTMP, and EDTMP differed so much in their chemical
behavior that a simultaneous enrichment from natural
samples cannot be achieved. Successful preconcentra-
tion of the phosphonates NTMP, EDTMP and DTPMP
from natural waters or wastewaters was achieved using
freshly precipitated CaCO
3
[32]. Recoveries at the 1 mM
level were 95–102% for an influent sample of a
wastewater treatment plant.
3.2. Concentrations in the environment
No measurements of phosphonates in natural samples
have been reported and only data for wastewaters are
available. This is mainly due to the fact that most
analytical methods are not able to quantify phospho-
nates in natural waters at low concentrations. Phospho-
nates have been measured in Swiss wastewater treatment
plants (WWTP) [38]. The concentrations of NTMP were
between o0.05 and 0.85 mM, of EDTMP between
o0.05 and 0.15 mM and of DTPMP between o0.05
and 1.7 mM. The highest concentration of DTPMP was
found in a WWTP influenced by textile industry.

Effluent samples from all investigated WWTP were with
the exception of one case always below the detection
limit. Another WWTP influenced by textile industry
contained NTMP concentrations in the influent between
0.2 and 1.1 mM [39].
The oxidative breakdown products of NTMP, IDMP
and FIDMP, have been detected in two WWTPs
receiving water from textile industry at concentrations
of 0.08 and 0.015 mM FIDMP and 0.49 and 0.3 mM
IDMP in the influent [34].
The expected concentrations in rivers are maximal
0.1 mM and with adsorption/photodegradation
included about 1–4 nM for NTMP and 25 nM for
HEDP [6,7]. Locally higher concentrations can be
expected because of intermitted discharge of cooling
tower water.
4. Surface reactions
4.1. Adsorption
Phosphonates adsorb very strongly onto almost all
mineral surfaces. This behavior distinguishes them from
the corresponding aminocarboxylates, which exhibit
much weaker interaction with mineral surfaces, espe-
cially near neutral pH [40]. Some of the investigated
adsorbents for phosphonates are calcite [41], clays
[42,43], aluminum oxides [44–46], iron oxides [47–49],
zinc oxide [49], hydroxyapatite [50,51] and barite [52].
For all those compounds very strong adsorption is
observed in the pH range of natural waters. Natural
materials are also very potent adsorbents for phospho-
nates, for example sewage sludge [20,21,39,53,54],

sediments [54] and soils [55]. Most of these studies,
however, have not considered that metal ions might
significantly alter the adsorption of a chelating agent
[56]. However, no influence of Fe(III), Zn, and Cu(II) on
phosphonate adsorption onto goethite was observed
[49]. This was explained by the very strong adsorption of
the uncomplexed phosphonate, which resulted in a
dissociation of the complex at the surface and separate
adsorption of the metal and the phosphonate onto
different surface sites. Fig. 3 shows the adsorption of
NTMP and the NTMP complexes with Zn, Cu and
Fe(III). Complete adsorption is observed up to a pH of 8
and no influence of the complexed metal on the shape of
the adsorption edge can be seen. In the pH range of
natural waters adsorption is therefore very strong. Other
phosphonates, e.g. HEDP, EDTMP and DTPMP,
adsorb in a similar manner to NTMP.
Ca has a very strong positive effect on phosphonate
adsorption [49]. In the presence of mM Ca concentra-
tions, phosphonates were completely adsorbed up to pH
of 12. The maximum surface concentration of phospho-
nates was also greatly enhanced in the presence of Ca.
This effect can be explained by the formation of ternary
surface-phosphonate-Ca complexes. Precipitation of Ca-
phosphonates on the surface can be ruled out [49]. When
evaluating the adsorptive capacity of a surface towards
phosphonates in a natural system, it is therefore
ARTICLE IN PRESS
B. Nowack / Water Research ] (]]]]) ]]]–]]] 5
necessary to conduct the adsorption experiments under

natural Ca concentrations.
4.2. Dissolution of minerals
Dissolution of a mineral phase by chelating agents can
be explained in terms of a ligand exchange process and is
related to the concentration of surface bound ligands.
The ligands weaken the metal–oxygen bonds on the
surface and enhance the release of metal ions from the
surface into the adjacent solution [57]. Reactions with
iron oxides are especially of great importance regarding
the speciation of the ligand in solution due to the very
strong Fe(III)-complexes. Reactions like this have been
observed in subsurface systems and have a pronounced
influence on the mobility of heavy metals [58,59].
Very little is known about the dissolution of iron
oxides by phosphonates. It was observed that HEDP
significantly mobilized Fe from natural sediments but no
information was given about the pH value of the
experiments [60]. No enhanced solubilization of Fe
from river sediment was observed at pH 3 by 0.01 M
NTMP [61].
The concentration of the Fe(III)-complex in the
presence of an iron oxide phase can be calculated when
the stability constants of the Fe(III)-complexes are
known. Fig. 4 shows the calculated Fe(III)NTMP
concentration in a system with NTMP and hydrous
ferric oxide (HFO). The speciation has been calculated
with the published stability constants for metal-NTMP
complexes [12] and the NTMP-Fe(III) stability con-
stants from [62] using the program ChemEQL [13]. The
formation of Fe(III)NTMP is important at pH values

below 6 in the absence of other metal ions. At pH above
7 NTMP is present as uncomplexed ligand. 1 mM Ca
and equimolar Zn depress the formation of
Fe(III)NTMP slightly. Cu which forms the strongest
complexes with NTMP has the largest influence on
Fe(III)NTMP formation. We can therefore conclude
that dissolution reactions are able to occur at low pH.
However, the strong adsorption of phosphonates,
especially at low pH, will limit the formation of
dissolved Fe(III)NTMP complexes and therefore no
dissolution will occur at low, environmentally relevant
concentrations.
4.3. Remobilization of metals
Metals adsorbed onto a mineral surface can be
solubilized by chelating agents. This process has always
been mentioned as one of the most adverse effects of
elevated chelating agent concentrations in the environ-
ment [63].
Metal adsorption in the presence of phosphonates has
been studied. There is an increase in Cu adsorption in
the presence of phosphonates at low pH, which is caused
by electrostatic effects [49]. At high pH there is a
mobilization of Cu due to the formation of dissolved
Cu-phosphonate complexes. Fig. 5 shows as an example
the influence of EDTMP on Cu adsorption onto
goethite. Overall, the influence of phosphonates on
metal adsorption in the natural pH range from 4 to 8 is
weak. We can therefore expect that phosphonates have
only a slight influence on metal remobilization in natural
systems. This was actually found during the study of

metal mobilization from river sediments by the phos-
phonate HEDP [60]. The only metal to be remobilized
was Fe whereas Zn, Cr, Ni, Cu, Pb and Cd were not
increased compared to a blank sample and only
dissolution of iron oxides was observed. Remobilization
of Cu, Cd, and Pb from river sediment was only
observed at NTMP concentrations above 0.1 mM [61].
ARTICLE IN PRESS
0
20
40
60
80
100
4681012
NTMP
ZnNTMP
CuNTMP
Fe(III)NTMP
NTMP/ 1 mM Ca
% adsorbed
pH
Fig. 3. Adsorption of 10 mM NTMP onto goethite in the
absence and presence of equimolar Zn, Cu, and Fe(III) and
1 mM Ca. Reprinted with permission from [49]. Copyright
(1999) American Chemical Society.
0
2 10
-7
4 10

-7
6 10
-7
8 10
-7
1 10
-6
4 4.5 5 5.5 6 6.5 7 7.5 8
NTMP
2 mM Ca
1 µM Zn
1 µM Cu
Fe(III)NTMP
pH
Fig. 4. Speciation of 1 mM NTMP in the presence of HFO and
in the absence and presence of 1 mM Zn and Cu and 2 mM Ca
without considering adsorption of the phosphonate. Log K
values from [12] and [62].
B. Nowack / Water Research ] (]]]]) ]]]–]]]6
We can therefore conclude that phosphonates probably
have only a marginal influence on metal mobilization in
the environment.
4.4. Precipitation
In many applications, phosphonates are added to
waters containing high concentrations of dissolved ions
to prevent the formation of precipitates. However, due
to the insolubility of some metal-phosphonates, the
phosphonates itself can precipitate. This phenomenon
often occurs in oil field applications when phosphonates
are injected into the subsurface and are left to interact

with calcium-containing formation waters [64,65].
The solubility of precipitates of NTMP with divalent
metals increases in the order CaoBaoSroMg [66]. The
insoluble Ca precipitates of DTPMP [67,68], NTMP
[69], and HEDP [70] and the precipitates of NTMP with
Fe(II) [71] and Fe(III) [72] have been investigated in
detail. Insoluble products of HEDP are also formed with
heavy metals such as Pb and Cd [73].
The precipitates are important in oil field applications
or in technical systems where high phosphonate and
high ion concentration occur simultaneously. In natural
waters or wastewaters, the phosphonate or Ca concen-
trations are far too low to exert any influence on
phosphonate concentrations. The solubility of NTMP in
the presence of 1 and 5 mM Ca is always above 200 mM
[49]. In natural waters precipitation reactions are there-
fore not important.
4.5. Inhibition of dissolution and precipitation
Scale formation, e.g. precipitation of calcium carbo-
nate or calcium sulfate, is a significant problem in
commercial water treatment processes including cooling
water technology, desalination and oil field applications.
This scale formation can be alleviated by the use of
chemical water treatment additives, known as ‘‘thresh-
old inhibitors’’. Phosphonic acids are among the most
potent scale inhibitors next to the polyphosphates. They
poison the crystal growth at concentrations far below
stoichiometric amounts of the reactive cations. Models
for this poisoning include inhibition of nucleation,
adsorption onto growth sites, distortion of the crystal

lattice, changes in surface charge and association with
precursors of crystal formation [74,75].
The morphology of crystals formed in the presence of
phosphonates is markedly different from those in the
absence of phosphonates [76]. Phosphonates limit the
size of the growing crystals and produce a lag phase in
which crystal growth is greatly reduced [77]. It was
found that the ability of different phosphonates to
inhibit crystal growth can be interpreted in terms of the
Langmuir adsorption model with the strongest inhibi-
tory effect from compounds that adsorb most strongly
[78].
Due to their inhibitory effect on crystal growth it has
been argued that phosphonates may have an adverse
effect on phosphate elimination by precipitation with
iron or aluminum salts during wastewater treatment
[79,80]. It was found that the phosphonates had an
influence on flocculation but it was possible to
compensate for it by increased addition of flocculating
agent. The resulting particulate precipitation products
were stabilized by the dispersing action of the phospho-
nates and not retained in the sand filter. Another study,
however, found no influence of HEDP on phosphate
elimination [60].
5. Degradation
5.1. Biodegradation
Phosphonates are similar to phosphates except that
they have a carbon–phosphorous (C–P) bond in place of
the carbon–oxygen–phosphorous (C–O–P) linkage. Due
to their structural similarity to phosphate esters,

phosphonates often act as inhibitors of enzymes due in
part to the high stability of the C–P bond [81]. In nature
bacteria play a major role in phosphonate biodegrada-
tion. The first phosphonate to be identified to occur
naturally was 2-aminoethylphosphonic acid [82].Itis
found in plants and many animals, mostly in mem-
branes. Phosphonates are quite common among differ-
ent organisms, from prokaryotes to eubacteria and
fungi, mollusks, insects and others but the biological
role of the natural phosphonates is still poorly under-
stood [83]. Due to the presence of natural phosphonates
in the environment, bacteria have evolved the ability to
metabolize phosphonates as nutrient sources. Those
bacteria able of cleaving the C–P bond are able to use
phosphonates as a phosphorous source for growth.
ARTICLE IN PRESS
Cu alone
Cu with NTMP
4681012
pH
% Cu adsorbed
0
20
40
60
80
100
Fig. 5. Adsorption of 10 mM Cu onto goethite in the absence
and presence of 10 mM NTMP. Reprinted with permission from
[49]. Copyright (1999) American Chemical Society.

B. Nowack / Water Research ] (]]]]) ]]]–]]] 7
Aminophosphonates can also be used as sole nitrogen
source by some bacteria [84].
The polyphosphonate chelating agents discussed here
differ greatly from natural phosphonates such as 2-
aminoethylphosphonic acid, because they are much
larger, carry a high negative charge and are complexed
with metals. Biodegradation tests with sludge from
municipal sewage treatment plants with HEDP and
NTMP showed no indication for any degradation based
on CO
2
formation [18,20,21]. An investigation of
HEDP, NTMP, EDTMP and DTPMP in standard
biodegradation tests also failed to identify any biode-
gradation [53]. It was noted, however, that in some tests
due to the high sludge to phosphonate ratio, removal of
the test substance from solution observed as loss of
DOC was observed. This was attributed to adsorption
rather than biodegradation because no accompanying
increase in CO
2
was observed.
However, bacterial strains capable of degrading
aminopolyphosphonates and HEDP under P-limited
conditions have been isolated from soils, lakes, waste-
water, activated sludge and compost [85]. The phospho-
nate phosphonobutane-tricarboxylic acid (PBTC) was
also rapidly degraded by microbial enrichment cultures
from a variety of ecosystems under conditions of low

phosphate availability [86].
The effects of other more accessible P sources on
phosphonate uptake and degradation are of great
environmental importance. Many environments such
as activated sludge, sediments and soils that act as a sink
for phosphonates are not characterized by a lack of P
most of the time. Because phosphonates are utilized
almost exclusively as P-source, little biodegradation can
be expected under these conditions. It has been
demonstrated, however, that simultaneous phosphate
and phosphonate utilization by bacteria can occur [87].
Adsorption of chelating agents by surfaces has been
shown to decrease the biodegradability. The easily
biodegradable NTA for example is much slower
degraded when adsorbed to mineral surfaces [88].It
can be expected that phosphonates with their higher
affinity to surfaces are much slower degraded in a
heterogeneous compared to a homogeneous system.
This was found to be the case for N-phosphonomethyl-
glycine, the phosphonate-containing herbicide glypho-
sate [89].
Phosphonates are therefore similar to EDTA [3,90] in
that little or no biodegradation is observed in natural
systems but that microorganisms have been isolated
from these environments capable of degrading the
compound.
5.2. Photodegradation
Photodegradation of the Fe(III)-complexes is an
important pathway of aminopolycarboxylate elimination
in the environment [91]. Phosphonates have a similar

reactivity. In distilled water and in the presence of Ca no
photodegradation of HEDP was observed but the
addition of Fe(III) and Cu(II) resulted in rapid photo-
degradation [20,92]. The mechanism of Fe(III)EDTMP
photodegradation [93] is equivalent to the photodegra-
dation of Fe(III)EDTA [94]. Fe(III)EDTMP is degraded
in a stepwise process from the parent compound through
ethylenediaminetrimethylenephosphonate and ethylene-
diaminedimethylenephosphonate to ethylenediaminemo-
nomethylenephosphonate which is stable in the presence
of Fe(III) and light. For EDTA the photodegradation of
the Fe(III)-complexes is the major elimination pathway
in natural waters [91]. We can therefore expect that
photodegradation is also very important for the fate of
dissolved phosphonates in surface waters. The photo-
degradation products of Fe(III)EDTA are readily
biodegradable, but this is not the case for phosphonates
[95].
5.3. Chemical degradation
Phosphonates are very stable and breakdown of
uncomplexed phosphonates requires long timescales
and severe chemical conditions. At temperatures above
200

C free NTMP decomposes to various breakdown
products [96,97]. These conditions are important for the
fate of the chelating agents in technical systems at
elevated temperatures, e.g. in cooling waters of power
plants, but not for natural waters. One study performed
at room temperature within the pH range of 2–10

reported that over a several month period, EDTMP
hydrolyzed under formation of phosphate, phosphite
and hydroxymethylphosphonate (HMP) [98]. Other
phosphonate-containing breakdown products were pre-
sent but were not identified. No information on the
kinetics or the percentage degraded was given.
In natural waters chelating agents and therefore the
phosphonates always occur in the form of metal
complexes. Studies on the chemical degradation of
phosphonates should therefore always include the
presence of metals. Degradation of the amine linkage-
containing phosphonates NTMP, EDTMP, and
DTPMP was negligible in metal-ion free oxygenated
solutions, but Ca, Mg, and Fe(II) brought about
conversion to free phosphate at a rate of approximately
1 percent per day [99]. Although the degradation was
classified as hydrolysis, the conversion rate dropped to
negligible levels in the absence of O
2
, indicating that
redox reactions play a role. HEDP, which does not
contain an amine linkage, degrades approximately 20-
times more slowly.
A loss of NTMP in different natural waters (river
waters, groundwaters) and appearance of the degrada-
tion products has been observed [21]. The conversion of
NTMP into iminodimethylenephosphonate (IDMP) and
ARTICLE IN PRESS
B. Nowack / Water Research ] (]]]]) ]]]–]]]8
HMP was attributed to abiotic hydrolysis and the

subsequent conversion to aminomethylphosphonate
(AMPA) and CO
2
to microbial degradation. The
authors performed a follow-up study in a medium that
was free of microorganisms, but contained mM levels of
Ca, Mg, K, and Na and trace levels (o1 mM) of Fe(III),
Cu(II), Mn(II), and Zn. Complete conversion of NTMP
to IDMP, HMP and AMPA occurred within 32 h.
Because multiple metal ions were present in these
investigations [21,99], it was not possible to identify
the catalytic agent.
A systematic study on the influence of metal ions on
phosphonate breakdown has been reported [33].No
breakdown of NTMP was observed in metal-free
systems and in the presence of Ca, Mg, Zn, Cu(II) and
Fe(III) which disagrees to previous results where
degradation of NTMP was observed in the presence of
Ca or Mg [21]. Very rapid degradation of aminopoly-
phosphonates occurred in the presence of Mn(II) and
molecular oxygen [33]. The half-life for the reaction of
NTMP in the presence of equimolar Mn(II) and in
equilibrium with 0.21 atm O
2
was 10 min at pH 6.5. The
reaction occurs more slowly under more alkaline or
acidic conditions. In the absence of oxygen no reaction
took place, indicating that an oxidation step was
involved. The presence of other cations such as Ca,
Zn, and Cu(II) can considerably slow down the reaction

by competing with Mn(II) for NTMP (Fig. 6). Catalytic
Mn(II) is regenerated by oxygen in cyclic fashion as the
reaction takes place. The hypothesized pathway is that
Mn(II)-phosphonate is oxidized by molecular oxygen to
the Mn(III)-phosphonate. In an intramolecular redox-
reaction the Mn(III) oxidizes the phosphonic acid and is
in turn reduced to Mn(II).
Formate, orthophosphate, IDMP and FIDMP break-
down products have been identified. Breakdown also
occurs in oxygen-free suspension of the Mn(III)
containing mineral manganite (MnOOH) and with
MnOOH in the presence of oxygen [100]. EDTMP
and DTPMP are also degraded in the presence of Mn(II)
and oxygen, although at a slower rate, but not the
amine-free HEDP [33]. Two of the breakdown products
of NTMP, IDMP and FIDMP, have been detected
in WWTP [34]. This indicates that manganese-
catalyzed oxidation of aminopolyphosphonate is likely
to be an important degradation mechanism in natural
waters.
5.4. Degradation during oxidation processes
Phosphonates present in natural waters may be
subject to oxidation and disinfection processes during
drinking water treatment. No information on the
behavior of phosphonates during chlorination is avail-
able. Ozonation of NTMP, EDTMP, and DTPMP
resulted in the rapid disappearance of the parent
compound in less than a minute [101]. 60–70% of the
degraded phosphonate was found as phosphate; AMPA
and phosphonoformic acid were also detected. The

amine-free HEDP was degraded much more slowly with
only 15% degradation after 30 min. The reaction path-
way of EDTMP during ozonation is equivalent to that
of EDTA [102]. The herbicide glyphosate was formed
during ozonation of EDTMP with concentration of up
to 10 nM [103]. The environmental fate, behavior and
analysis of both AMPA and glyphosate has received
considerable attention [10] and the formation of these
compounds during ozonation of an aminopolypho-
sphonate may change the risk analysis of these
compounds considerably.
6. Speciation
The speciation of chelating agents in the environment
can be calculated based on the known stability constants
of the metal–ligand complexes and the measured total
concentrations of metals and chelating agents. This
approach has been used to predict the speciation of
EDTMP in Rhine water [6]. The simulated speciation was
dominated by CuEDTMP and ZnEDTMP. HEDP was
predicted to be mainly complexed with Ca and NTMP
with Cu and Zn [104,105]. But how accurate are such
calculations? There are several points to consider: In
speciation calculations it is always assumed that equili-
brium has been reached in the system. This is not always
the case. Some metal complexes of aminocarboxy-
lates have very slow exchange kinetics [106]. It has been
found for example that Fe(III)EDTA is not in equilibrium
with other metals in river water due to slow exchange
kinetics of Fe(III)EDTA [107]. Almost nothing is
known about the exchange kinetics of metal-phosphonate

ARTICLE IN PRESS
0
20
40
60
80
100
120
0 100 200 300 400 500
no oxygen
only Mn(II)
Mn(II)/ 0.5 mM Ca
Mn(II)/ 10 µM Zn
% of inital NTMP
time (minutes)
Fig. 6. Oxidation of 10 mM NTMP in the presence of 10 mM
Mn(II) in the presence and absence of dissolved oxygen and
competing metal ions at pH 7.0. Reprinted with permission
from [33]. Copyright (2000) American Chemical Society.
B. Nowack / Water Research ] (]]]]) ]]]–]]] 9
complexes and therefore all equilibrium calculations have
to be treated with care.
Most calculations also do not consider that besides
the chelating agent of interest other chelating agents
and natural ligands are present in the water and com-
pete for available metals. The interaction between
the binding properties of phosphonates and fulvic
acids is weak [108] but it has been shown that
considering the natural ligands for Cu and Zn is critical
for obtaining an accurate speciation of chelating agents

[109].
In the following section a speciation model for three
phosphonates is developed, based on a river water
sample from Switzerland with well-known composition
of metals, anthropogenic and natural ligands [110].
These ligands compete with the phosphonates for the
same metals and have to be included in the speciation
calculation. The concentration of the phosphonates in
the calculations was set to 20 nM, comparable to EDTA
at that location.
The speciation was calculated for HEDP and NTMP
with the constants from the IUPAC report [12] and for
DTPMP with the constants from [111]. If only total
metals and the phosphonates are taken into considera-
tion, speciation is dominated by Cu for DTPMP, Ca for
HEDP, and Ca, Mg, Zn and Cu for NTMP. Including
EDTA and NTA does not change the speciation
significantly; however, as soon as the natural ligands
for Cu and Zn are considered, the calculated speciation
for NTMP and DTPMP changes drastically. For
NTMP the Cu and Zn complexes disappear totally due
to the very strong binding of Cu to the natural ligands
and CaNTMP and MgNTMP are dominant. For
DTPMP the Ca and Mg complexes also become very
important with more than 60% of the DTPMP
complexed by these metals. CuDTPMP is only a minor
species under these conditions. For HEDP the alkaline
earth metals Ca and Mg are the major bound metals
under all conditions. The fraction of other metal
complexes is never above 0.1%. It can be concluded

that phosphonates are most probably complexed to
alkaline earth metals in natural waters. This calculation
shows that considering the natural ligands is crucial for
obtaining a reasonable result for phosphonate speciation
(Table 2).
Analytical methods have been developed to determine
directly the speciation of aminocarboxylate chelating
agents [112–114]. In principle these methods should also
be applicable to phosphonates. A recent very promising
method uses anion-exchange chromatography coupled
to ICP-MS for the separation of metal-chelating agent
complexes [35,36]. The method is also applicable to
phosphonates and it has been shown that the
CuEDTMP complex can be determined. The use of
these methods to determine the speciation of phospho-
nates in natural waters is needed.
7. Behavior during wastewater treatment
The studies about the behavior of phosphonates
during wastewater treatment can be divided into two
groups: field studies with the addition of elevated
concentrations of phosphonates to the influent of the
treatment plant and investigations at ambient concen-
trations.
The elimination of phosphonates during wastewater
treatment was found to be very high, even with high
concentrations of added phosphonates of about 10 mM.
Elimination of 9.7 mM HEDP in a field experiment was
about 60% during the sedimentation and 90–97.5%
during the biological step with simultaneous FeCl
3

precipitation [60]. Lower removal rates of 50–60% were
found with the addition of 5–10 mM HEDP and 3–7 mM
NTMP to a WWTP without iron-addition [115]. The
behavior of 4.5–12 mM DTPMP was followed through
the different treatment steps [39]. It was found that the
DTPMP removal in the biological step was 95%. After
the precipitation step with aluminum sulfate about 97%
of the added DTPMP had been removed. This
investigation has shown that even without simultaneous
addition of iron or aluminum salts, very good removal
in the biological step can be achieved.
The second group of studies investigated the fate of
phosphonates that are already present in the influent of
the WWTP. For a 13-day field study a total amount of
117 mol of DTPMP was found in the influent of the
WWTP compared to an effluent load of 17 mol, meaning
that the removal efficiency was 85% [38].
Elimination of NTMP and EDTMP from another
WWTP was at least 80% and 70%, respectively [38].
Because the concentration in the effluent was below the
detection limit, this removal efficiency is the lower limit.
ARTICLE IN PRESS
Table 2
Calculated species distribution of HEDP, NTMP, and DTPMP
in river water. Conditions: 20 nM phosphonates, 29.4 nM
EDTA, 8.6 nM NTA and natural ligands for Cu, Zn and Ni
Ca Mg Zn Cu
% of total phosphonate
HEDP
No other ligands 88 12 0 0.1

With EDTA, NTA, natural
ligands
88 12 0 0
NTMP
No other ligands 33 25 11 28
With EDTA, NTA, natural
ligands
55 42 0 0
DTPMP
No other ligands 0 0 24 76
With EDTA, NTA, natural
ligands
41 21 35 2
B. Nowack / Water Research ] (]]]]) ]]]–]]]10
The fate of NTMP was followed in another WWTP
receiving wastewater from textile industry [39]. The load
of NTMP in the influent was 324 mol during the 2-week
period. No NTMP was detected in the effluent. Taking
the detection limit of 0.05 mM as the upper limit of
NTMP concentration the maximal effluent load for the
2-week period can be calculated to be 23 mol. The
removal efficiency of the WWTP was therefore at least
93%. Also the two breakdown products of NTMP,
IDMP and FIDMP, were present at much higher
concentrations in the influent than in the effluent [34],
with a removal of 87% FIDMP and 96% IDMP.
The results from field studies and field measurements
have shown that phosphonates are removed very
efficiently in most WWTP and pose only little risk to
the receiving waters.

8. Conclusions
*
The very strong adsorption of phosphonates results
in low dissolved concentrations.
*
Little or no remobilization of metals by phospho-
nates is expected.
*
No biodegradation of phosphonate-chelating agents
is observed in the environment.
*
The Fe(III)-complexes are rapidly photodegraded.
*
Rapid degradation of aminopolyphosphonates oc-
curs in the presence of Mn(II).
*
An analytical method for trace measurements in
natural waters is urgently needed.
*
No analytical information on speciation of phospho-
nates in the environment is available.
Acknowledgements
The author is indebted to Jean-Claude Bollinger and
V
!
eronique Deluchat for their fruitful comments to
earlier versions of this manuscript and to Susan Tandy
for editing the English. This review was prepared
in part during a stay at the University of Limoges,
France. The support of the Reinhold-Beitlich-Founda-

tion, T .ubingen, Germany, is greatly acknowledged.
References
[1] Means JL, Alexander CA. The environmental biogeo-
chemistry of chelating agents and recommendations for
the disposal of chelated radioactive wastes. Nucl Chem
Waste Manage 1981;2:183–96.
[2] Wolf K, Gilbert PA. EDTA—Ethylenediaminetetraacetic
acid. In: Hutzinger O (Ed.), The Handbook of Environ-
mental Chemistry, vol. 3, Part F. Berlin, Heidelberg:
Springer, 1992. p. 243–59.
[3] Bucheli-Witschel M, Egli T. Environmental fate and
microbial degradation of aminopolycarboxylic acids.
FEMS Microbiol Rew 2001;25:69–106.
[4] Knepper TP, Weil H. Study on the entry of synthetic
chelating agents and compounds exhibiting complexing
properties into the aquatic environment. Vom Wasser
2001;97:193–232.
[5] Nowack B. Environmental chemistry of aminopolycar-
boxylate chelating agents. Environ Sci Technol 2002;36:
4009–16.
[6] Gledhill WE, Feijtel TCJ. Environmental properties and
safety assessment of organic phosphonates used for
detergent and water treatment applications. In: Hutzinger
O, editor. The handbook of environmental chemistry,
vol. 3, Part F. Berlin, Heidelberg: Springer, 1992,
pp. 261–85.
[7] Jaworska J, van Genderen-takken H, Hanstveit A, van de
Plasche E, Feijtel T. Environmental risk assessment of
phosphonates, used in domestic laundry and cleaning
agents in the Netherlands. Chemosphere 2002;47:655–65.

[8] Atkinson D. Toxicological properties of glyphosate—a
summary. In: Atkinson D, editor. The herbicide glypho-
sate. London: Butterworths, 1985. p. 127–33.
[9] Franz JE, Mao MK, Sikorski JA. Glyphosate: a unique
global herbicide. ACS Monogr 1997;189:653.
[10] Stalikas CD, Konidari CN. Analytical methods to
determine phosphonic and amino acid group-containing
pesticides. J Chromatogr A 2001;907:1–19.
[11] de Klerk JMH, van Dijk A, van het Schip AD,
Zonnenberg BA, van Rijk PP. Pharmacokinetics of
rhenium-186 after administration of rhenium-186-HEDP
to patients with bone metastases. J Nucl Med 1992;33:
646–51.
[12] Popov K, R
.
onkk
.
om
.
aki H, Lajunen LHJ. Critical
evaluation of stability constants of phosphonic acids.
Pure Appl Chem 2001;73:1641–77.
[13] M.uller B. ChemEQL, 2.0 A program to calculate
chemical speciation, equilibria, titrations, dissolution,
precipitation, adsorption, simple kinetics, px-py dia-
grams. EAWAG/ ETH, 1996.
[14] Fleisch H. Bisphosphonates: a new class of drugs in
diseases of bone and calcium metabolism. Recent Results
Cancer Res 1989;116:1–28.
[15] May HB, Nijs H, Godecharles V. Phosphonates. Multi-

functional ingredients for laundry detergents. Household
Pers Prod Ind 1986;23:50–4.
[16] Davenport B, DeBoo A, Dubois F, Kishi A. CEH report:
chelating agents. SRI Consulting, Menlo Park, CA, USA,
2000.
[17] van Hullebusch E, Chazal PM, Deluchat V. Influence of
phosphonic acids and EDTA on bacterial copper
toxocity. Toxicol Environ Chem 2002;82:75–91.
[18] Huber L. Investigations about the biological degradabil-
ity and fish toxicity of 2 organic chelating agents on
phosphonic acid basis (ATMP and HEDP). Tenside
Deterg 1975;12:316–22.
[19] Sch
.
oberl PH. Ecologically relevant data of non-tenside
components in washing and cleaning agents. Tenside
Surfactants Deterg 1988;25:99–107.
[20] Steber J, Wierich P. Properties of hydroxyethane diphos-
phonate affecting its environmental fate: degradability,
ARTICLE IN PRESS
B. Nowack / Water Research ] (]]]]) ]]]–]]] 11
sludge adsorption, mobility in soils, and bioconcentra-
tion. Chemosphere 1986;15:929–45.
[21] Steber J, Wierich P. Properties of aminotris(methylene-
phosphonate) affecting its environmental fate: degrad-
ability, sludge adsorption, mobility in soils, and
bioconcentration. Chemosphere 1987;16:1323–37.
[22] Calvin G, Long PH, Stitzel KA, Anderson RL, Balmbra
RR, Bruce RD, Bhatt A, Miller PM, Broadmeadow A.
Ethyelenediaminetetra(methylenephosphonic acid) —

genotoxicity, biodistribution, and subchronic toxicity in
rats. Food Chem Toxicol 1988;26:601–10.
[23] Francis MD, Centner RL. The development of dipho-
sphonates as significant health care products. J Chem
Educ 1978;55:760–6.
[24] Weiss J, H
.
agele G. Ion-chromatographic analysis of
inorganic and organic complexing agents. Fresenius Z
Anal Chem 1987;328:46–50.
[25] Tsch
.
abunin G, Fischer P, Schwedt G. On the analysis of
polymethylenephosphonic acids. I. A systematic survey of
the ion chromatography of organophosphonic acids.
Fresenius Z Anal Chem 1989;333:111–6.
[26] Tsch
.
abunin G, Fischer P, Schwedt G. On the analysis of
polymethylenephosphonic acids. II. A systematic survey
of post-column derivatization in ion chromatography.
Fresenius Z Anal Chem 1989;333:117–22.
[27] Vaeth E, Sladek P, Kenar K. Ion chromatography of
polyphosphates and phosphonates. Fresenius Z Anal
Chem 1987;329:584–9.
[28] Tewari KMJ, van Stroe-Bieze SAM. Analysis of amine-
containing phosphonates in detergent powders by anion-
exchange chromatography with pulsed amperometric
detection. J Chromatogr A 1997;771:155–61.
[29] Thompson R, Grinberg N, Perpall H, Bicker G, Tway P.

Separation of organophosphonates by ion chromatogra-
phy with indirect photometric detection. J Liquid
Chromatogr 1994;17:2511–31.
[30] Shamsi SA, Danielson ND. Ribonucleotide electrolytes
for capillary electrophoresis of polyphosphates and
polyphosphonates with indirect photometric detection.
Anal Chem 1995;67:1845–52.
[31] Klinger J, Sacher F, Brauch H-J, Maier D. Determination
of organic phosphonates in aqueous samples using liquid
chromatography/ particle-beam mass spectrometry. Acta
Hydrochim Hydrobiol 1997;25:79–86.
[32] Nowack B. Determination of phosphonates in natural
waters by ion-pair high performance liquid chromato-
graphy. J Chromatogr A 1997;773:139–46.
[33] Nowack B, Stone AT. Degradation of Nitrilotris(methy-
lenephosphonic acid) and related (amino)phosphonate
chelating agents in the presence of manganese and
molecular oxygen. Environ Sci Technol 2000;34:4759–65.
[34] Nowack B. Determination of phosphonic acid breakdown
products by high performance liquid chromatography
after derivatization. J Chromatogr A 2002;942:185–90.
[35] Ammann AA. Determination of strong binding chelators
and their metal complexes by anion-exchange chromato-
graphy and inductively coupled plasma mass spectro-
metry. J Chromatogr A 2002;947:205–16.
[36] Ammann AA. Speciation of heavy metals in environ-
mental water by ion chromatography coupled to ICP-
MS. Anal Bioanal Chem 2002;372:448–52.
[37] Frigge E, Jackwerth E. Preconcentration and determina-
tion of organophosphonic acids: application to natural

waters. Anal Chim Acta 1991;254:63–73.
[38] Nowack B. Behavior of phosphonates in wastewater
treatment plants of Switzerland. Water Res 1998;32:
1271–9.
[39] Nowack B. Aminopolyphosphonate removal during
wastewater treatment. Water Res 2002;36:4636–42.
[40] Stone AT, Knight MA, Nowack B. Speciation and
chemical reactions of phosphonate chelating agents in
aqueous media. In: Lipnick RL, Mason RP, Phillips ML,
Pittman CU, editors. Chemicals in the environment: fate,
impacts and remediation, ACS Symposium Series No.
806. Washington, DC: American Chemical Society, 2001.
p. 59–94.
[41] Xyla AG, Mikroyannidis J, Koutsoukos PG. The
inhibition of calcium carbonate precipitation in aqueous
media by organophosphorous compounds. J Colloid
Interface Sci 1992;153:537–51.
[42] Fischer K. Sorption of chelating agents (HEDP and
NTA) onto mineral phases and sediments in aquatic
model systems, Part I: sorption onto clay minerals.
Chemosphere 1991;22:15–27.
[43] Morillo E, Undabeytia T, Maqueda C. Adsorption of
glyphosate on the clay mineral montmorillonite: effect of
Cu(II) in solution and adsorbed on the mineral. Environ
Sci Technol 1997;31:3588–92.
[44] Laiti E,
.
Ohman L-O, Nordin J, Sj
.
oberg S. Acid/base

properties and phenylphosphonic acid complexation at
the aged d-Al
2
O
3
/water interface. J Colloid Interface Sci
1995;175:230–8.
[45] Laiti E,
.
Ohmann L-O. Acid/ base properties and
phenylphosphonic acid complexation at the boehmite/
water interface. J Colloid Interface Sci 1996;183:
441–52.
[46] Liu Y, Yu L, Guo J. Adsorption of PBTCA on alumina
surfaces and its influence on the fractal characteristics of
sediments. J Colloid Interface Sci 2000;227:164–70.
[47] Day GM, Hart BT, McKelvie ID, Beckett R. Influence of
natural organic matter on the sorption of biocides
onto goethite, II. Glyphosate. Environ Technol 1997;18:
781–94.
[48] Nowack B, Stone AT. Adsorption of phosphonates onto
the goethite-water interface. J Colloid Interface Sci
1999;214:20–30.
[49] Nowack B, Stone AT. Influence of metals on the
adsorption of phosphonates onto goethite. Environ Sci
Technol 1999;3:3627–33.
[50] Jung A, Bisaz S, Fleisch H. The binding of pyropho-
sphate and two diphosphonates by hydroxyapatite
crystals. Calcif Tissue Res 1973;11:269–80.
[51] Chirby D, Franck S, Troutner DE. Adsorption of

153
Sm-
EDTMP on calcium hydroxyapatite. Int J Radiat Appl
Instrum Part A 1988;39:495–9.
[52] Black SN, Bromley LA, Davey RJ, Dobbs B, Rout JE.
Interactions at the organic/inorganic interface: binding
motifs for phosphonates at the surface of barite crystals. J
Chem Soc Faraday Trans 1991;87:3409–14.
[53] Horstmann B, Grohmann A. Investigations into the
biodegradability of phosphonates. Vom Wasser 1988;70:
163–78.
ARTICLE IN PRESS
B. Nowack / Water Research ] (]]]]) ]]]–]]]12
[54] Fischer K. Sorption of chelating agents (HEDP and
NTA) onto mineral phases and sediments in aquatic
model systems. Part II: Sorption onto sediments and
sewage sludges. Chemosphere 1992;24:51–62.
[55] Held S. Th environmental behavior of chelating agents on
phosphomic acid basis. Textilveredlung 1989;24:394–8.
[56] Nowack B, L.utzenkirchen J, Behra P, Sigg L. Modeling
the adsorption of metal-EDTA complexes onto oxides.
Environ Sci Technol 1996;30:2397–405.
[57] Stumm W. Reactivity at the mineral–water interface:
dissolution and inhibition. Colloids Surf A 1997;120:
143–66.
[58] Davis JA, Kent DB, Rea BA, Maest AS, Garabedian SP.
Influence of redox environment and aqueous speciation
on metal transport in groundwater. In: Brown DS, editor.
editor, Metals in groundwater. Boca Raton: Lewis
Publishers, 1993. p. 223–73.

[59] Jardine PM, Jacobs GK, O’Dell JD. Unsaturated
transport processes in undisturbed heterogeneous porous
media: II. Co-contaminants. Soil Sci Soc Am J 1993;
57:954–62.
[60] M .uller G, Steber J, Waldhoff H. The effect of hydro-
xyethane diphosphonic acid on phosphate elimination
with FeCl
3
and remobilization of heavy metals: results
from laboratory experiments and field trials. Vom Wasser
1984;63:63–78.
[61] Bordas F, Bourg ACM. Effect of complexing agents
(EDTA and ATMP) on the remobilization of heavy
metals from a polluted river sediment. Aquat Geochem
1998;4:201–14.
[62] Lacour S, Deluchat V, Bollinger JC, Serpaud B.
Complexation of trivalent cations (Al(III), Cr(III),
Fe(III)) with two phosphonic acids in the pH range of
fresh waters. Talanta 1998;46:999–1009.
[63] M .uller G, F
.
orstner U. Experimental mobilization of
copper and zinc from aquatic sediments by some
polyphosphate substitutes in detergents. Z Wasser Ab-
wasser Forsch 1976;9:150–2.
[64] Browning FH, Fogler HS. Effect of synthesis parameters
on the properties of calcium phosphonate precipitates.
Langmuir 1995;11:4143–52.
[65] Gerbino AJ.Quantifying the retention, release of poly-
phosphonates in oil and gas producing formations using

surface complexation and precipitation theory. Disserta-
tion, Rice University, Texas, 1996.
[66] Samakaev RK, Dyatlova NM, Dytyuk LT. The solubility
in water of the nitrilotrimethylenephosphonates of
the group II elements. Russ J Inorg Chem 1984;29:
1819–20.
[67] Oddo JE, Tomson MB. The solubility and stoichiometry
of calcium-diethylenetriaminepenta(methylene phospho-
nate) at 70

C in brine solutions at 4.7 and 5.0 pH. Appl
Geochem 1990;5:527–32.
[68] Kan AT, Oddo JE, Tomson MB. Formation of two
calcium diethylenetriaminepentakis(methylene phospho-
nic acid) precipitates and their physical chemical proper-
ties. Langmuir 1994;10:1450–5.
[69] Pairat R, Sumeath C, Browning FH, Fogler HS.
Precipitation and dissolution of calcium-ATMP precipi-
tates for the inhibition of scale formation in porous
media. Langmuir 1997;13(1):791–1798.
[70] Browning FH, Fogler HS. Effect of precipitating condi-
tions on the formation of calcium-HEDP precipitates.
Langmuir 1996;12:5231–8.
[71] Friedfeld SJ, He S, Tomson MB. The temperature and
ionic strength dependence of the solubility product
constant of ferrous phosphonate. Langmuir 1998;14:
3698–703.
[72] Zholnin AV, Zudov VG, Leitsin VA, Nosova RL,
Smirnov EN. Preparation of the iron complex of
nitrilotrimethylenephosphonic acid from zinc-production

wastes. J Appl Chem USSR 1990;63:751–4.
[73] Deluchat V, Serpaud B, Caullet C, Bollinger J-C.
Protonation and complexation constants of 1-hydro-
xyethane-1,1
0
-diphosphonic acid (HEDP) with divalent
cations: a study of insoluble complexes of HEDP with
Pb(II) and Cd(II). Phosphorous Sulfur Silicon 1995;
104:81–92.
[74] Gratz AJ, Hillner PE. Poisoning of calcite growth viewed
in the atomic force microscope (AFM). J Cryst Growth
1993;129:789–93.
[75] Gal J-Y, Bollinger JC, Tolosa H, Gache N. Calcium
carbonate solubility: a reappraisal of scale formation and
inhibition. Talanta 1996;43:497–1509.
[76] Benton WJ, Collins IR, Grimsey IM, Parkinson GM,
Rodger SA. Nucleation, growth and inhibition of barium
sulfate-controlled modification with organic and inor-
ganic additives. Faraday Discuss 1993;95:281–97.
[77] Davis RV, Carter PW, Kamrath MA, Johnson DA, Reed
PE. The use of modern methods in the development of
calcium carbonate inhibitors for cooling water systems.
In: Amjad Z, editor. Mineral scale formation and
inhibition. New York: Plenum Press, 1995. p. 33–46.
[78] Zieba A, Stehuraman G, Perez F, Nancollas GH,
Cameron D. Influence of organic phosphonates on
hydroxyapatite crystal growth kinetics. Langmuir 1996;
12:2853–8.
[79] Horstmann B, Grohmann A. The influence of phospho-
nates on phosphate elimination. Part 1: 1-hydroxyethane-

1,1-diphosphonic acid (HEDP). Z Wasser Abwasser
Forsch 1984;17:177–81.
[80] Horstmann B, Grohmann A. The influence of phospho-
nates on phosphate elimination. Part 2: 2-phosphono-
butane-1,2,4-tricarbonic acid (PBTC), aminotri(methyle-
nephosphonic acid) (ATMP) and ethylenediamintetra(-
methylenephosphonic acid) (EDTMP). Z Wasser
Abwasser Forsch 1986;19:236–40.
[81] Huang J, Chen R. An overview of recent advances on the
synthesis and biological activity of a-aminophosphonic
acid derivatives. Heteroatom Chem 2000;11:480–92.
[82] Horiguchi M, Kandatsu M. Isolation of 2-aminoethane
phosphonic acid from rumen protozoa. Nature
1959;184:901–2.
[83] Wanner BL. Molecular genetics of carbon-phosphorous
bond cleavage in bacteria. Biodegradation 1994;5:175–84.
[84] McMullan G, Quinn JP. The utilization of aminoalkyl
phosphonic acids as sole nitrogen source by an environ-
mental bacterial isolate. Lett Appl Microbiol
1993;17:135–8.
[85] Schowanek D, Verstraete W. Phosphonate utilization by
bacterial cutures and enrichments from environmental
samples. Appl Environ Microbiol 1990;56:895–903.
ARTICLE IN PRESS
B. Nowack / Water Research ] (]]]]) ]]]–]]] 13
[86] Raschke H, Rast H-G, Kleinst .uck R, Sicius H, Wischer
D. Utilization of 2-phosphonobutane-1,2,3-tricarboxylic
acid as source of phosphorous by environmental bacterial
isolates. Chemosphere 1994;29:81–8.
[87] Schowanek D, Verstraete W. Phosphonate utilization by

bactaria in the presence of alternative phosphorous
sources. Biodegradation 1990;1:45–53.
[88] Bolton H, Girvin DC. Effect of adsorption on the
biodegradation of nitrilotriacetate by Chelatobacter
heintzii. Environ Sci Technol 1996;30:2057–65.
[89] Zaranyika MF, Nyandoro MG. Degradation of glypho-
sate in the aquatic environment: an enzymatic kinetic
model that takes into account microbial degradation of
both free and coloidal (or sediment) particle adsorbed
glyphosate. J Agric Food Chem 1993;41:838–42.
[90] N
.
ortemann B. Biodegradation of EDTA. Appl Microbiol
Biotechnol 1999;51:751–9.
[91] Kari FG, Giger W. Modeling the photochemical degra-
dation of EDTA in the River Glatt. Environ Sci Technol
1995;29:2814–27.
[92] Fischer K. Distribution and elimination of HEDP in
aquatic test systems. Water Res 1993;27:85–493.
[93] Matthijs E, De Oude NT, Bolte M, Lemaire J. Photo-
degradation of ferric ethylenediaminetetra(methylene-
phosphonic acid) (EDTMP) in aqueous solution. Water
Res 1989;23:845–51.
[94] Lockhart HB, Blakeley RV. Aerobic photodegradation of
X(N) chelates of ethylenedinitrilotetraacetate (EDTA):
implications for natural waters. Environ Lett 1975;9:
19–31.
[95] Nowack B, Baumann U. Biodegradation of the photo-
lysis products of Fe(III)EDTA. Acta Hydrochim Hydro-
biol 1998;26:104–8.

[96] Martell AE, Motekaitis RJ, Fried AR, Wilson JS,
MacMillan DT. Thermal decomposition of EDTA,
NTA, and nitrilotrimethylenephosphonic acid in aqueous
solution. Can J Chem 1975;53:3471–6.
[97] Kaslina NA, Polyakova IA, Kessenikh AV, Zhadanov
BV, Rudomino MV, Churilina NV, Kabachnik MI.
Thermal decomposition of nitrilotrimethylenephosphonic
acid in aqueous solution. J Gen Chem USSR 1985;
55:472–5.
[98] Tsch
.
abunin G, Fischer P, Schwedt G. On the analysis of
polymethylenephosphonic acids. III. Stability of ethylene-
diaminetetramethylenephosphonic acod (EDTMP) in aqu-
eous solution. Fresenius Z Anal Chem 1989;333:123–8.
[99] Schowanek D, Verstraete W. Hydrolysis and free radical
mediated degradation of phosphonates. J Environ Qual
1991;20:769–76.
[100] Nowack B, Stone AT. Heterogeneous and homogeneous
oxidation of nitrilotrismethylenephoshonate (NTMP) in
the presence of oxygen and manganese (II, III). J Phys
Chem B 2002;106:6227–33.
[101] Klinger J, Sacher F, Brauch HJ, Maier D, Worch E.
Behavior of phosphonic acids during drinking water
treatment. Vom Wasser 1998;91:15–27.
[102] Gilbert E, Hoffmann-Glewe S. Ozonation of ethylene-
diaminetetraacetate (EDTA) in aqueous solution, influ-
ence of pH value and metal ions. Water Res 1990;24:
39–44.
[103] Klinger J, Lang M, Sacher F, Brauch HJ, Maier D,

Worch E. Formation of glyphosate and AMPA during
ozonation of waters containing ethylenediaminetetra(-
methylenephosphonic acid). Ozone Sci Eng 1998;20:
99–110.
[104] Deluchat V, Bollinger JC, Serpaud B, Caullet C. Divalent
cations speciation with three phosphonate ligands in the
pH-range of natural waters. Talanta 1997;44:897–907.
[105] Lacour S, Deluchat V, Bollinger JC, Serpaud B. Influence
of carbonate and calcium ions on the phosphonate
complexation with Cu, Zn, Cd and Ni in fresh waters:
an evaluation of thermodynamic constants and a
chemical model. Environ Technol 1999;20:249–57.
[106] Margerum DW. Exchange reactions of multidentate
ligand complexes. Rec Chem Prog 1963;24:237–51.
[107] Xue HB, Sigg L, Kari FG. Speciation of EDTA in
natural waters: exchange kinetics of FeEDTA in river
water. Environ Sci Technol 1995;29:59–68.
[108] Deluchat-Antony V, Bollinger JC, Serpaud B, Caullet C.
Influence of some washing powder components on
copper(II) and calcium(II) complexation with fulvic acids.
Int J Environ Anal Chem 1998;68:123–35.
[109] Sigg L, Xue HB. Metal speciation: concepts, analysis and
effects. In: Stumm W, editor. Chemistry of aquatic
systems: local and global perspectives. Brussels, Luxem-
bourg: ECSC, EEC, EAEC, 1994. p. 153–81.
[110] Nowack B, Xue HB, Sigg L. Influence of natural and
anthropogenic ligands on metal transport during infiltra-
tion of river water to groundwater. Environ Sci Technol
1997;31:866–72.
[111] Rizkalla EN. Metal chelates of phosphonate-containing

ligands. Rev Inorg Chem 1983;5:223–304.
[112] Nowack B, Kari FG, Hilger SU, Sigg L. Determination
of adsorbed and dissolved EDTA-species in natural
waters. Anal Chem 1996;68:561–6.
[113] Nirel PM, Pardo PE, Landry JC, Revaclier R. Method
for EDTA speciation determination: application to
sewage treatment plant effluents. Water Res 1998;32:
3615–20.
[114] Bedsworth WW, Sedlak DL. Determination of metal
complexes of ethylenediaminetetraacetate in the presence
of organic matter by high-performance liquid chromato-
graphy. J Chromatogr A 2001;905:157–62.
[115] Metzner G. Behavior of organic chelating agents on
phosphonic acid basis in wastewater treatment plants.
Beitr Abwasser Fisch Flussbiol 1990;44:323–36.
ARTICLE IN PRESS
B. Nowack / Water Research ] (]]]]) ]]]–]]]14