NITRILOTRIACETIC ACID

Nitrilotriacetic acid
NTA
Nitrilotriacetic acid is organic chelating agent used to control the concentration of metal ions in aqueous systems.

Nitrilotriacetic Acid is a white, crystalline solid compound. Nitrilotriacetic acid is mainly used as a chelating and eluting agent and is found in laundry detergents

Nitrilotriacetic acid is a tricarboxylic acid and a NTA

Nitrilotriacetic acid (NTA) is the aminopolycarboxylic acid with the formula N(CH2CO2H)3. 
Nitrilotriacetic acid is a colourless solid that is used as a chelating agent, which forms coordination compounds with metal ions (chelates) such as Ca2+, Co2+ , Cu2+, and Fe3+.

Nitrilotriacetic acid is a chelating agent which forms coordination compounds with metal ions. Nitrilotriacetic acid is used in complexometric titrations and as well as for protein isolation and purif ication in the His-tag method.


EC / List no.: 205-355-7
CAS no.: 139-13-9
Mol. formula: C6H9NO6

Nitrilotriacetic acid is used as a chelating and sequestering agent, and as a builder in synthetic detergents. 
It is also used as an eluting agent in the purification of rare earth elements, as a boiler feedwater additive, in water and textile treatment, in metal plating and cleaning and in pulp and paper processing.

Nitrilotriacetic acid and its salts and complexes are not known to occur naturally

Alternate Names:N,N-Bis(carboxymethyl)glycine; NTA; Tris(carboxymethyl)amine

Application: Nitrilotriacetic acid is acts as an excellent chelating agent

Nitrilotriacetic acid Chemical Properties, Uses, Production

Chemical Properties
White, crystalline powder.Insoluble in water and most organic solvents; forms mono-, di-, and tribasic salts that are water soluble. Combustible. 70% biodegradable.

Chemical Properties
Nitrilotriacetic acid is a crystalline compound.

Uses
Nitrilotriacetic acid is a chelating agent which forms coordination compounds with metal ions. Nitrilotriacetic acid is used in complexometric titrations and as well as for protein isolation and purif ication in the His-tag method.

Uses
Used in sequestration of metals; chelometric analysis.

General Description
Odorless white solid. Sinks in and mixes with water.

Air & Water Reactions
Water Insoluble.

Reactivity Profile
Nitrilotriacetic acid is incompatible with strong oxidizers, aluminum, copper, copper alloy and nickel. Nitrilotriacetic acid is also incompatible with strong bases.


Chemical nature: The active ingredient contained in Nitrilotriacetic acid is nitrilotriacetic acid (NTA-H3) with CAS-No. 139-13-9.

Nitrilotriacetic acid is NTA, C6H9NO6, is an aminocarboxylic acid with four functional groups.

Appearance: Nitrilotriacetic acid is a fine white powder.

Handling and Storage of Nitrilotriacetic acid


Materials    
The following materials can be used for tanks and drums:
a)    Stainless steel 1.4541 – AISI 321 stainless steel (X6 CrNiTi 1810)
b)    Stainless steel 1.4571 – AISI 316 Ti stainless steel (X6 CrNiMoTi 17122)
c)    Stainless steel 1.4306 – AISI 321 L stainless steel (X2 CrNi 1911)
d)    High-density polyethylene (HDPE)
e)    Low-density polyethylene (LDPE)


Shelf life    
Provided it is stored properly and drums are kept tightly sealed, Nitrilotriacetic acid has a shelf life of at least 36 months in its original packaging.
 

Properties    
Some physical properties of Nitrilotriacetic acid are listed in the table below. 
These are typical values only and not all of them are monitored on a regular basis. 
They are correct at the time of publication and do not necessarily form part of the product specification. 


Nitrilotriacetic acid    Unit    Value
Physical form (25 °C): powder
Molecular weight (M.W.)    g/mol: 191

Concentration (pot. Titration with FeCl3-solution) 
calculated as trisodium salt (NTA-Na3 ): approx. 135 %
calculated as free acid (NTA-H3 ) :approx. 100 %

Bulk density (DIN ISO 697, 40 mm diam.)    g/L: approx. 800
pH value(DIN 19268, 1% in water, 23 °C)    :approx. 2.2 (slurry)
Calcium binding capacity (BASF method, pH 11) mg CaCO3/g t.q.: approx. 525
Water content(DIN EN 13267, Karl Fischer)%: approx. 0.2
Melting point (DIN 51004) °C: approx. 245
Solubility in water (BASF method, 25 °C g in 1 litre: approx. 1

Distribution of particles    
The following curve shows the distribution of particles of Nitrilotriacetic acid (all values are approximate):

 

Complex formation    
The most important property of Nitrilotriacetic acid is its ability to form watersoluble complexes with polyvalent ions (e.g. calcium, magnesium, lead, copper, zinc, cadmium, mercury, manganese, iron) over a wide pH range from 2 to 13.5. 
NTA usually forms 1 : 1 complexes, i. e. 1 mol of NTA chelates binds to 1 mol of metal ions, but it can also form 2 : 1 complexes with some metals if a stoichiometric excess of NTA is present. 
These complexes remain stable, especially in alkaline media and even at temperatures of up to 100 °C.

From the law of mass action, the equation for the stability constant K for 1 : 1 complexes can be written as follows:

[MeZ(m-n)-]K =[Men+] [Zm-]

where
[MeZ(m-n)-] is the concentration of the chelate that is formed,
[Men+] is the concentration of free, positively charged metal ions, [Zm-] is the concentration of the ligand anion, in this case NTA, K    is the stability constant for the chelate.
Logarithmic stability constants (log K) for complexes of MGDA and selected metal ions:
Metal ion    log K
Fe3+    15.9
Hg2+    14.6
Cu2+    12.9
Ni2+    11.5
Pb2+    11.3
Zn2+    10.7
Co2+    10.4
Cd2+    9.8
Fe2+    8.3
Mn2+    7.5
Ca2+    6.4
Mg2+    5.5
Ba2+    4.8

NTA-H3 is a tribasic acid that dissociates in three steps. 
The acid dissociation constants pKa are as follows.

NTA-H3    pKa1    1.9
NTA-H2-    pKa2    2.5
NTA-H2-    pKa3    9.7

In aqueous solutions, Nitrilotriacetic acid competes for metal ions with other anions, such as hydroxide, sulphate, sulphide, carbonate and oxalate, that form sparingly soluble metal salts. 
The formation of chelates reduces the concentration of free metal ions [Men+] to such an extent that the solubility products of many sparingly soluble metal salts are no longer exceeded. 
The result is that the salts no longer precipitate or may even redissolve.

Conditional stability constants [log Kcond] take into account the stability constant K as well as the acid base dissociation equilibria.
 

The following curves show the conditional stability constants for selected NTA chelates

Chemical stability: Nitrilotriacetic acid is chemically very stable.

Nitrilotriacetic acid exhibits a higher stability than other organic chelating agents such as citric acid, tartaric acid and gluconates – especially at elevated temperatures.
Whereas inorganic sequestring agents (e.g. phosphates) may hydrolyse at high temperatures, Nitrilotriacetic acid is stable – even when heated to 200 °C under pressure.

Nitrilotriacetic acid melts at approx. 245 °C.

Nitrilotriacetic acid is resistant to strong acids and bases. 
It is gradually broken down by chromic acid, potassium permanganate and other strong oxidizing agents. 
Stability in the presence of hydrogen peroxide, percarbonate and perborate is sufficient for joint application. 
Nevertheless, we do not recommend combining Nitrilotriacetic acid and peroxides in liquid formulations.

Sodium hypochlorite and other substances that release chlorine cause Nitrilotriacetic acid to decompose. 
Alkaline earth and heavy metal complexes are broken down.

Corrosion: Nitrilotriacetic acid stabilizes polyvalent metal ions, which means that it can increase the rate at which metals dissolve. 
Nevertheless, with the exception of aluminium, an oxidizing agent such as air always has to be present for corrosion to take place. 
Unalloyed steel is prone to corrosion in media that contain air, but corrosion can be reduced substantially if the pH is in the alkaline range and can be eliminated almost completely if oxygen and other oxidizing agents are excluded. 
Steel that is cleaned with Nitrilotriacetic acid in the slightly alkaline range, which is the optimum pH range for the Nitrilotriacetic acid, is much less prone to corrosion than if it is cleaned with acids.

The only type of corrosion that has been with Nitrilotriacetic acid is uniform corrosion: pitting or stress cracking have not been observed in media with a low chloride content. 
One of the advantages of Nitrilotriacetic acid is that it can be supplied with very low chloride contents.

The following information on materials is of a very general nature, because corrosion depends on many different factors such as exposure to air, galvanic corrosion caused by the presence of different materials and by the flow patterns of liquids. 
The compatibility of Nitrilotriacetic acid with different materials needs to be tested in each individual case.
 

Ecology and toxicology: Nitrilotriacetic acid is readily biodegradable in standard OECD tests, it is completely mineralised
and it does not form any persistent metabolites. 
The removal rate for Nitrilotriacetic acid due to biodegradation usually more than in sewage treatment plants is 95%.

Safety: We are not aware of any ill effect that can result from using Nitrilotriacetic acid for the purpose for which it is intended and from processing it in accordance with current practices.
According to the experience that we have gained over many years and other information at our disposal, Nitrilotriacetic acid does not exert harmful effects on health, provided it is used properly, due attention is given to the precautions necessary for handling chemicals, and the information and advice given in our Safety Data Sheets are observed.

Labelling: Please consult the current Safety Data Sheets for information on the classification and labelling of our products and other information relevant to safety.

Nitrilotriacetic acid is commercially available as the free acid and as the sodium salt. It is produced from ammonia, formaldehyde, and sodium cyanide or hydrogen cyanide. 
Worldwide capacity is estimated at 100 thousand tonnes per year.
NTA is also cogenerated as an impurity in the synthesis of EDTA, arising from reactions of the ammonia coproduct.

Coordination chemistry and applications
NTA is a tripodal tetradentate trianionic ligand.

The uses of NTA are similar to those of EDTA, both being chelating agents. 
It is used for water softening and as a replacement to sodium and potassium triphosphate in detergents, and cleansers.

In one application, NTA as a chelating agent removes Cr, Cu, and As from wood that had been treated with chromated copper arsenate.

Laboratory uses
In the laboratory, this compound is used in complexometric titrations. A variant of NTA is used for protein isolation and purification in the His-tag method.
The modified NTA is used to immobilize nickel on a solid support. This allows purification of proteins containing a tag consisting of six histidine residues at either terminus.

The his-tag binds the metal of metal chelator complexes. 
Previously, iminodiacetic acid was used for that purpose. Now, nitrilotriacetic acid is more commonly used.

For laboratory uses Ernst Hochuli et al. 1987 coupled the NTA ligand and Nickel-ions to agarose beads.
This Ni-NTA Agarose is the most used tool to purify his tagged proteins via affinity chromatography


Nitrilotriacetic acid
Nitrilotriacetic acid
nitrilotriacetic acid

NTA
EU. Content Labelling for Detergents (648/2004)
CAS names
Glycine, N,N-bis(carboxymethyl)-


IUPAC names
2,2',2''-nitrilotriacetic acid
2-[bis(carboxymethyl)amino]acetic acid
Glycine, N,N-bis(carboxymethyl)-
N,N-Bis(carboxymethyl)glycine, NTA, Tris(carboxymethyl)amine
Nitrilotriacetic Acid
Nitrilotriacetic acid
nitrilotriacetic acid
Nitrilotriacetic acid
nitrilotriacetic acid
Nitrilotriacetic Name
Nitrilotriessigsäure
NTA acid

Trade names
Acetic acid, nitrilotri-
alpha, alpha`, alpha``-Trimethylaminetricarboxylic acid
Glycine, N,N-bis(carboxymethyl)-
Nitrilo-2,2`,2``-triacetic acid
nitrilotriacetic acid

NTA

Synonyms: Chel 300; Complexon I; HamshipreR NTA acid; IDRANALR I; Titriplex I; Triglycollamic acid; Triglycine; a,a',a"-Trimethylaminetricarboxylic acid; Nitrilo-2,2',2"-triacetic acid; Versene NTA acid

Synonyms: Nitrilo-2,2′,2′′-triacetic acid; nitrilotris(methylenecarboxylic acid); NTA; triglycine; triglycollamic acid; α,α′,α′′-trimethylaminetricarboxylic acid


NITRILOTRIACETIC ACID AND ITS SALTS
This substance was considered by a previous working group, in 1989 (IARC, 1990).
Since that time, new data have become available, and these have been incorporated into the monograph and taken into consideration in the present evaluation.

Nitrilotriacetic acid
Chem. Abstr. Serv. Reg. No.: 139-13-9
Deleted CAS Reg. No.: 26627-44-1; 26627-45-2; 80751-51-5
Chem. Abstr. Name: N,N-Bis(carboxymethyl)glycine
IUPAC Systematic Name: Nitrilotriacetic acid
Synonyms: Nitrilo-2,2′,2′′-triacetic acid; nitrilotris(methylenecarboxylic acid); NTA;triglycine; triglycollamic acid; α,α′,α′′-trimethylaminetricarboxylic acid


Nitrilotriacetic acid, sodium salt
Chem. Abstr. Serv. Reg. No.: 10042-84-9
Chem. Abstr. Name: N,N-Bis(carboxymethyl)glycine, sodium salt
IUPAC Systematic Name: Nitrilotriacetic acid, sodium salt
Synonyms: Nitrilotriacetic acid sodium salt; NTA sodium salt; NTA, sodium salt;
sodium aminotriacetate; sodium nitriloacetate; sodium nitrilotriacetate; sodium NTA


Nitrilotriacetic acid, monosodium salt
Chem. Abstr. Serv. Reg. No.: 18994-66-6
Chem. Abstr. Name: N,N-Bis(carboxymethyl)glycine, monosodium salt
IUPAC Systematic Name: Nitrilotriacetic acid, monosodium salt
Synonyms: Monosodium nitrilotriacetate; NTA, monosodium salt


Nitrilotriacetic acid, disodium salt
Chem. Abstr. Serv. Reg. No.: 15467-20-6
Chem. Abstr. Name: N,N-Bis(carboxymethyl)glycine, disodium salt
IUPAC Systematic Name: Nitrilotriacetic acid, disodium salt
Synonyms: Disodium hydrogen nitrilotriacetate; disodium nitrilotriacetate; nitrilotriacetic acid disodium salt; NTA, disodium salt

Nitrilotriacetic acid, disodium salt, monohydrate
Chem. Abstr. Serv. Reg. No.: 23255-03-0
Chem. Abstr. Name: N,N-Bis(carboxymethyl)glycine, disodium salt, monohydrate
IUPAC Systematic Name: Nitrilotriacetic acid, disodium salt, monohydrate
Synonyms: Disodium nitrilotriacetic acid monohydrate; NTA, disodium salt, monohydrate


Nitrilotriacetic acid, trisodium salt
Chem. Abstr. Serv. Reg. No.: 5064-31-3
Deleted CAS Reg. No.: 37291-81-9
Chem. Abstr. Name: N,N-Bis(carboxymethyl)glycine, trisodium salt
IUPAC Systematic Name: Nitrilotriacetic acid, trisodium salt
Synonyms: Nitrilotriacetic acid trisodium salt; NTA trisodium salt; NTA, trisodium
salt; trisodium nitrilotriacetate; trisodium 2,2′,2′′-nitrilotriacetate; trisodium NTA


Nitrilotriacetic acid, trisodium salt, monohydrate
Chem. Abstr. Serv. Reg. No.: 18662-53-8
Chem. Abstr. Name: N,N-Bis(carboxymethyl)glycine, trisodium salt, monohydrate
IUPAC Systematic Name: Nitrilotriacetic acid, trisodium salt, monohydrate
Synonyms: NTA, trisodium salt, monohydrate; trisodium nitrilotriacetate monohydrate

NITRILOTRIACETIC ACID

139-13-9

2,2',2''-nitrilotriacetic acid

Triglycollamic acid

Nitrilotriacetate

Aminotriacetic acid

Complexon I

Trilon A

NTA

Glycine, N,N-bis(carboxymethyl)-

N,N-Bis(carboxymethyl)glycine

2-[bis(carboxymethyl)amino]acetic acid

Komplexon I

Titriplex I

Versene NTA acid

Nitrilotriessigsaeure

Hampshire NTA acid

Tri(carboxymethyl)amine

Tris(carboxymethyl)amine

Acetic acid, nitrilotri-

Nitrilo-2,2',2''-triacetic acid

MFCD00004287

CHEL 300

NCI-C02766

Nitrilotriaceticacid

Nitrilotriacetic acid (NTA)

UNII-KA90006V9D

alpha,alpha',alpha''-Trimethylaminetricarboxylic acid

2-(bis(carboxymethyl)amino)acetic acid

CHEBI:44557

KA90006V9D

Nitriloacetate

DSSTox_CID_939

DSSTox_RID_75878

Nitrilotriacetic acid, 99%

DSSTox_GSID_20939

CAS-139-13-9

CCRIS 436

Aminotriethanoic acid

N,N-Bis(carboxymethyl)glysine

HSDB 2853

Kyselina nitrilotrioctova [Czech]

Kyselina nitrilotrioctova

NSC 2121

EINECS 205-355-7

BRN 1710776

AI3-52483

H3nta

Potassium cadmium nitrilotriacetate

EINECS 256-488-2

nitrilotriacetic-acid

PubChem15712

WLN: QV1N1VQ1VQ

EC 205-355-7

Cambridge id 5122183

NitrilotriessigsA currencyure

ACMC-1BQ36

N(CH2-COOH)3

NTA (Nitrilotriacetic acid)

SCHEMBL20409

4-04-00-02441 (Beilstein Handbook Reference)

KSC176I7T

MLS000069464

BIDD:ER0361

Glycine,N-bis(carboxymethyl)-

Nitrilo-2,2''-triacetic acid

CHEMBL1234848

DTXSID6020939

CTK0H6479

NSC2121

HMS2232K17

CCG-2133

NSC-2121

STR02791

ZINC1849692

Nitrilotriacetic acid, p.a., 99%

Tox21_202195

Tox21_300156

ANW-20498

BBL002469

SBB006593

STK387109

AKOS005441655

DB03040

MCULE-5696288379

KS-00000V43

NCGC00091141-01

NCGC00091141-02

NCGC00091141-03

NCGC00091141-04

NCGC00254116-01

NCGC00259744-01

BP-30104

Cadmate(1-), (N,N-bis((carboxy-kappaO)methyl)glycinato(3-)-kappaN,kappaO)-, potassium (1:1), (T-4)-

Cadmate(1-), (N,N-bis((carboxy-kappaO)methyl)glycinato(3-)-kappaN,kappaO)-, potassium, (T-4)-

I536

SMR000054748

2-[bis(carboxymethyl)amino]essigsäure

DB-042463

FT-0631809

N0098

NITRILOTRIACETIC ACID ACS GRADE 100G

Nitrilotriacetic acid, Sigma Grade, >=99%

ST50306920

T7392

C14695

Nitrilotriacetic acid, ACS reagent, >=99.0%

84771-EP2270017A1

84771-EP2301941A1

84771-EP2305808A1

90564-EP2272834A1

90564-EP2301929A1

90564-EP2301935A1

90564-EP2305674A1

90564-EP2372017A1

90564-EP2374780A1

90564-EP2374781A1

Nitrilotriacetic acid, BioUltra, >=99.0% (T)

.alpha.,.alpha.''-Trimethylaminetricarboxylic acid

Q425340

J-007239

F1905-6980

Z1889996324

Nitrilotriacetic acid, ACS reagent, for complexometry, >=98%

Nitrilotriacetic acid, United States Pharmacopeia (USP) Reference Standard

Potassium (N,N-bis(carboxymethyl)glycinato(3-)-N,O,O',O'')cadmate(1-)

Toxicity and Environment
Nitriloacetic acid can cause eye, skin, and respiratory tract irritation; and can cause kidney and bladder damage. 
The compound is anticipated to have the potential to cause human cancers.

In contrast to EDTA, NTA is easily biodegradable and is almost completely removed during wastewater treatment.
The environmental impacts of NTA are minimal. Despite widespread use in cleaning products, the concentration in the water supply is too low to have a sizeable impact on human health or environmental quality.


Nitrilotriacetic Acid
CAS Number
139-13-9
Synonym
AI-52483; Aminotriacetic acid; n,n-bis(carboxymethyl)glycine; Complexon I; Hampshire NTA acid; NCI-C02766; NTA; Titriplex I; Tri(carboxymethyl)amine; Triglycine; TGA; Triglycolamic acid; Trilon A; Versene NTA acid

Occurrence/Use
Chelating agent in laundry and other detergents; water softening

VERSENE NTA Products—General Purpose Chelating Agents
 VERSENE NTA 148—Na3
NTA—Used in cleaning products
 VERSENE NTA 152—Na3
NTA—General purpose chelant
  VERSENE NTA LC—Na3
NTA—Low color version of VERSENE NTA 148
 VERSENE NTA Crystal—Na3
NTA—Dry, crystalline form of VERSENE NTA 148 or VERSENE NTA 152
 VERSENE NTA Acid—H3
NTA—Dry, acid form of VERSENE NTA 148 or VERSENE NTA 152


VERSENE NTA LC chelating agent is a low-color version of VERSENE NTA 148 chelating agent. 
NTA is a readily biodegradable, low molecular weight, general purpose chelant. It is classified as readily biodegradable according to OECD definition. 
It should be considered when (1) maximum stability of the metal chelate complex is not necessary; and (2) cost effective chelation of hardness ions at an alkaline pH is required.


versene nta acid 
Name: Nitrilotriacetic acid
CAS: 139-13-9
Molecular Formula: C6H9NO6
Molecular Weight: 191.14
 HomeCASCAS 139 CAS 139-13-9
versene nta acid - Names and Identifiers
Name    Nitrilotriacetic acid
Synonyms    alpha,alpha',alpha''-trimethylaminetricarboxylic acid
aminotriacetic acid
chel 300
hampshire nta acid
nitrilo-2,2',2''-triacetic acid
N,N-bis(carboxymethyl)glycine
NTA
Complexon I
titriplex i
tri(carboxymethyl)amine
triglycine
triglycollamic acid
Trilone A
versene nta acid
ai3-52483
chel300
complexoni
Glycine,N,N-bis(carboxyme
hampshirentaacid
komplexoni
kyselinanitrilotrioctova
kyselinanitrilotrioctova(czech)
Trimethylamine-α,α',α"-tricarboxylic acid
Nitrilo triacetic acid
CAS    139-13-9
EINECS    205-355-7


Water Conditioning, Industrial
John M. Donohue, in Encyclopedia of Physical Science and Technology (Third Edition), 2003

III.B.3 Chelation
Metal cations found in boiler water, such as calcium, magnesium, iron, and copper, can be solubilized to prevent deposition and scale formation. 
The functional agents in this type of treatment are known as chelants. Chelants are organic, anionic chemicals that form soluble compounds with the metals. 
The two chief chelating chemicals used in industrial boiler water treatment are ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA).

Chelants are added continuously in the stoichiometric quantity required to solubilize any metal contaminants present in the boiler water. 
The stabilities of the resultant metal–chelate reaction compounds vary considerably. 
EDTA has more coordination sites than NTA and forms stronger soluble complexes with the metal cations. 
However, EDTA in excess of that required for contaminant chelation can decompose in the boiler water and large excesses of EDTA and NTA can react with the magnetite (Fe3O4) film protecting the boiler. 
Other anions present in the boiler water (e.g., phosphate, silicate, and hydroxide) tend to compete with chelants, limiting their effectiveness.

For these reasons, chelant treatment chemistry must be precise. 
Frequent analytical testing of the feedwater and internal boiler water is necessary to maintain a proper chelant feed rate.

Polymeric dispersants are used to supplement chelant treatment. 
Polymers are particularly effective in dispersing metal oxides and sludges that form due to chelant instabilities. 
Proper application of a chelant–dispersant treatment results in clean heat transfer surfaces and efficient boiler operations.

Chelant Treatments
Realizing the shortcomings of residual phosphate chemistry in the way it handles feedwater hardness contamination (precipitation), alternative treatment chemistries were developed.

The first was the use of chelants to solubalize the hardness contaminants. The most common chelants used were ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA). 
Both EDTA and NTA form soluble complexes with calcium and magnesium that are stable to relatively high temperatures, up to 6.8 MPa g (1000 psi g). 
The removal of hardness contaminants from the boiler, now in a soluble form, are no longer limited by the continuous blowdown’s limited ability to remove suspended solids from the circulating boiler water. 
If the species in question is soluble in the feedwater, remains soluble in the boiler water and is nonvolatile, the continuous blowdown removes that species at 100% efficiency.

Theoretically, if the required stoichiometric ratio of chelant to hardness were maintained, there would be no accumulation of hardness-based deposits in the boiler. 
However in practice, there are variations in the level of hardness contaminants in the feedwater, and some overfeed must be applied continually to account for these variations. 
This overfeed is typically controlled to result in a small residual chelant concentration in the boiler water above that required for the actual hardness. 
It was found that this boiler water chelant residual must be controlled very tightly because high levels of the residual can result in corrosion of the boiler base material. 
This corrosion is most likely to occur in areas of high fluid velocity or turbulence in the boiler. 
For this reason, chelant residual control limits vary as a function of boiler operating pressure and range from about 1–5 mg l−1 (1–5 ppm). 
Chelants have been applied at boiler pressures over 6.8 MPa g (1000 psi g) early in their history but later were only commonly applied up to about 2.7 MPa g (400 psi g) for EDTA and about 6.2 MPa g (900 psi g) for NTA.


Nitrilotriacetic acid is a derivative of acetic acid, N(CH2COOH)3. It is a complexing (sequestering) agent that forms stable complexes also with Zn2+

Synonyms
nitrilo-2,2',2''-triacetic acid
Nitrilotriacetate
Triglycine
Triglycollamic acid
α,α',α''-trimethylaminetricarboxylic acid

139-13-9 [RN]
1710776 [Beilstein]
2,2',2''-Nitrilotriacetic acid [ACD/IUPAC Name]
2,2',2''-Nitrilotriessigsäure [German] [ACD/IUPAC Name]
205-355-7 [EINECS]
4-04-00-02441 [Beilstein]
a,a',a''-Trimethylaminetricarboxylic Acid
Acide 2,2',2''-nitrilotriacétique [French] [ACD/IUPAC Name]
ácido nitrilotriacético [Portuguese]
AJ0175000
aminotriacetic acid
Glycine, N,N-bis(carboxymethyl)- [ACD/Index Name]
KA90006V9D
Kwas nitrylotrioctowy [Polish]
Kyselina nitrilotrioctova [Czech]
MFCD00004287 [MDL number]
N,N-bis(carboxymethoxy)glycine
N,N-Bis(carboxymethyl)glycine
nitriloacetate
nitrilotriacetate
nitrilotriacetic acid [Wiki]
Nitrilotriessigsaeure
NTA
Ntana3
tri(carboxymethyl)amine
Triglycine
Triglycollamic acid
Tris(carboxymethyl)amine
UNII-KA90006V9D
α,α',α''-Trimethylaminetricarboxylic acid
(Bis-carboxymethyl-amino)-acetic acid
2-(bis(carboxymethyl)amino)acetic acid
2-(bis(carboxymethyl)amino)ethanoic acid
2,2',2''-nitrilotriacetic acid (non-preferred name)
2-[bis(carboxymethyl)amino]acetic acid
2-[Bis(carboxymethyl)amino]acetic acid, NTA
acetic acid, nitrilotri-
Aminotriethanoic acid
Benzoic acid, 4-(aminomethyl)- (9CI)
Complexon I [Trade name]
Glycine, N,N-bis (carboxymethyl)-
H3nta
http://en.atomaxchem.com/139-13-9.html
https://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI:44557
IDRANAL [Trade name]
IDRANAL I [Trade name]
Komplexon I [Trade name]
N,N-bis(carboxymethyl)-glycine
N,N-Bis(carboxymethyl)glysine
Nitrilo-2,2', 2''-triacetic acid
nitrilo-2,2',2''-triacetic acid
nitrilo-tri-acetic acid
nitrilotriacetic acid 98%
nitrilotriacetic acid, 99%
nitrilotriacetic acid, cp
nitrilotriacetic acid, reagent, acs
QV1N1VQ1VQ [WLN]
STR02791
titriplex i
Titriplex(R) I
triglycollamic acid,98.5%
Trilon A
α,α',α''-trimethylaminetricarboxylic acid

Roles Classification
Chemical Role(s):    Bronsted acid
A molecular entity capable of donating a hydron to an acceptor (Bronsted base).
(via oxoacid )
chelator
A ligand with two or more separate binding sites that can bind to a single metallic central atom, forming a chelate.
(via NTA )
Bronsted base
A molecular entity capable of accepting a hydron from a donor (Bronsted acid).
(via organic amino compound )

nitrilotriacetic acid is a NTA 
nitrilotriacetic acid  is a tricarboxylic acid 
nitrilotriacetic acid is conjugate acid of nitrilotriacetate(1−) 

Incoming    
2,2'-[(2-amino-2-oxoethyl)imino]diacetic acid has functional parent nitrilotriacetic acid 
nitrilotriacetate(1−) is conjugate base of nitrilotriacetic acid 

IUPAC Name
N,N-bis(carboxymethyl)glycine

IUPAC Name
N,N-bis(carboxymethyl)glycine
Synonyms    
α,α',α''-trimethylaminetricarboxylic acid    
Complexon I Deutsch    
H3nta    
Komplexon I 
N(CH2‒COOH)3    
nitrilo-2,2',2''-triacetic acid    
Nitrilotriacetate    
NITRILOTRIACETIC ACID    
Nitrilotriacetic acid    
Nitrilotriessigsäure    
NTA    
tri(carboxymethyl)amine    
triglycine    
Triglycollamic acid    
Trilon A    


Nitrilotriacetic acid (NTA) or its derivatives are present in  many  complex structures  in which  a  metal  atom is bonded  to  several  atoms  of the  polydentate  complex- ing agent.  However, only a few structures of unchelated acid, anion or NTA derivatives are known: nitrilotriacetic acid  (Stanford,  1967);  calcium  nitrilotriacetate  dihy- drate (Whitlow,  1972);  2,2',2"-nitrilotriethanol (Mootz, Brodalla &  Wiebcke, 1989); N-methylnitrilotriacetamide (Skrzypczak-Jankun  &  Smith,  1994a).  
In  the  last two of these structures, the central N  atom is not protonated and  the  N--C  bonds  are  shorter  (1.467  and  1.463 ,A, respectively)  and  the  C--N--C  angles  smaller  (110.7 and  110.9 °,  respectively) than  in the  protonated  com- pounds. 
In CaNTA.2H20,  five of the six NTA O  atoms are  bound  to  metal  ions,  but  each  O  atom  is  joined to  a  different  Ca  ion,  so  that  the  NTA  zwitterion  is not the chelating ligand, but part of a  three-dimensional ionic  network similar  to that  seen  in  NTA itself


Nitrilotriacetic acid participates as a  multidentate ligand in many metal chelation compounds of A1, B, Bi, Ca, Co, Cr, Cu, Fe, Mo, Nd, Ni, Pb, Ti, W, Zn and Zr. 
The struc- ture of this popular ligand has been refined and compared with that of calcium nitrilotriacetate dihydrate [Whitlow (1972). 
Acta  Cryst. B28,  1914-1919], which is  another structure where this ligand is not affected by chelation

According to data submitted under section 71 of CEPA 1999 and other publicly available sources, NTA is reported to be used in Canada in institutional and industrial cleaning products, vehicle cleaners, asphalt paving, fertilizers, photographic developer solutions and descaling products for oil extraction and mining activities (Environment Canada 2009a). According to information in the available literature, institutional and industrial cleaning products constitute the largest Canadian application of NTA; these include general cleaners, degreasers, vehicle washes, disinfectants, sanitizers, laundry detergents and detergents for mechanical dish washers (Mueller et al. 2006; Glauser et al. 2007; Ahmed 2009). 
Other applications of NTA in Canada involve its function as a chelating agent in a variety of industrial processes, such as the treatment of boiler water and in pulp and paper processes to produce paper and paperboard products. 
Previously, NTA was proposed in the scientific literature as a therapeutic chelating agent for manganese poisoning and for the treatment of iron overloading.


NTA is a known impurity in ethylenediaminetetraacetic acid (EDTA) and its salts, collectively known as edetates (Dow Chemical Company 1987; Crosbie et al. 2003; Hart 2005). 
Edetates are chelating agents that may be used in household cleaning products, cosmetic formulations, foods, agricultural products, pharmaceutical products and industrial processes (Hart 2005). Edetates are also used to treat heavy metal poisoning and to reduce blood cholesterol (Lanigan and Yamarik 2002). According to the US Pharmacopeia (USP 2000a, b, c) and European Pharmacopoeia (EP 2001) and the Food Chemicals Codex (2009 emails from Food Directorate, Health Canada, to Risk Management Bureau, Health Canada; unreferenced), the maximum limit of NTA in edetates is 0.1% by weight.

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