Thermal Decomposition of EDTA, NTA, and Nitrilotrimethylenephosphonic Acid in Aqueous Solution

1975 ◽  
Vol 53 (22) ◽  
pp. 3471-3476 ◽  
Author(s):  
A. E. Martell ◽  
R. J. Motekaitis ◽  
A. R. Fried ◽  
J. S. Wilson ◽  
D. T. MacMillan
Keyword(s):  
Ethylenediaminetetraacetic Acid ◽  
Water Solution ◽  
Iminodiacetic Acid ◽  
Nitrilotriacetic Acid ◽  
Decomposition Reaction ◽  
Order Rate Constant ◽  
Hydrolytic Cleavage ◽  
Stable Pair ◽  
Primary Products ◽  
Decarboxylation Reaction

The decomposition of ethylenediaminetetraacetic acid (EDTA) in water solution at 200 and 260 °C, nitrilotriacetic acid (NTA) at 260 and 293 °C, and of nitrilotrimethylenephosphonic acid (NTPO) at 260 °C was studied by n.m.r. as a function of time at pH 9.5 and decomposition rates and products were determined. The primary (fast) decomposition reaction of EDTA involves the hydrolytic cleavage of the ethylenic C—N bond to produce the relatively stable pair: N-(2-hydroxyethyl)iminodiacetic acid and iminodiacetic acid. NTA does not cleave below 260 °C but decomposes at about 290 °C and above through a stepwise decarboxylation reaction. NTPO cleaves hydrolytically at 260 °C at two C—N bonds to produce aminomethylenephosphonic acid and 2 mol of hydroxymethylenephosphonic acid. The further breakdown of the primary products of EDTA at higher temperatures occurs by the loss of carbon dioxide producing the corresponding methylamines, concomitantly with the hydrolytic cleavage of the remaining CH2CH2—N bond giving ethylene glycol. The pseudo first order rate constant kobs for NTA decarboxylation at 293 °C and pH 9.3 is 0.19 ± 0.01 h−1. The value of kobs for EDTA hydrolysis at 200 °C is 1.4 ± 0.2 h−1.

Oxidation of CrIII aminocarboxylate complexes by hydrous manganese oxide: products and time course behaviour

2015 ◽  
Vol 12 (1) ◽  
pp. 33 ◽  
Author(s):  
Richard F. Carbonaro ◽  
Alan T. Stone
Keyword(s):  
Manganese Oxide ◽  
Time Course ◽  
Ethylenediaminetetraacetic Acid ◽  
Environmental Concern ◽  
Iminodiacetic Acid ◽  
Nitrilotriacetic Acid ◽  
Product Distribution ◽  
Hydrous Manganese Oxide ◽  
Wide Ph Range ◽  
Ph Range

Environmental context Oxidation of CrIII (trivalent chromium) to CrVI (hexavalent chromium) is of environmental concern because CrVI is a known mutagen and carcinogen. Our results show that hydrous manganese oxide (HMO) is capable of oxidising soluble CrIII complexed with iminodiacetic acid and nitrilotriacetic acid to CrVI at appreciable rates. CrVI production from soluble CrIII organic complexes is therefore expected to occur in natural and engineered systems that contain HMO. Abstract MnIII,IV (hydr)oxides are believed to be the principal oxidants of CrIII in the subsurface. In nearly all previous work on this subject, the CrIII reactant was prepared from inorganic salts (e.g. nitrate, chloride, sulfate). In our present work, CrIII complexes with the synthetic chelating agents iminodiacetic acid (IDA) and nitrilotriacetic acid (NTA) were reacted with hydrous manganese oxide (HMO) over a wide pH range to examine rates of reaction and product distribution. Capillary electrophoresis was used to quantify changes in reactant (CrIII–IDA and CrIII–NTA) and product (CrVI, free IDA and free NTA) concentrations as a function of time. In addition, a small number of experiments were performed using solutions prepared from CrIII alum (KCr(SO4)2·12H2O(s)) as the CrIII reactant. CrIII–IDA and CrIII–NTA were oxidised to CrVI, but rates were considerably lower than those obtained using inorganic CrIII. Within the timescales of our experiments, complete conversion of CrIII–NTA occurred at pH >7, but not under moderately acidic conditions, even when there was a large stoichiometric excess of HMO. MnCl2 addition experiments indicated that the observed reaction inhibition was attributable to MnII generation during the reaction. Our previous work has shown that citric acid, IDA, NTA and ethylenediaminetetraacetic acid solubilise CrIII from amorphous Cr(OH)3(s) at appreciable rates. The results of this study show that HMO is capable of oxidising the resulting soluble CrIII complexes, providing a viable mechanism for CrIII oxidation to CrVI over a wide pH range.

Gel self-assembly of lanthanum aminopolycarboxylates with skeleton structures and adsorptions of gases

2021 ◽  
Author(s):  
Si-Yuan Wang ◽  
Zhenlang Xie ◽  
Xin Dong ◽  
Zhao-Hui Zhou
Keyword(s):  
Self Assembly ◽  
Ethylenediaminetetraacetic Acid ◽  
Iminodiacetic Acid ◽  
Nitrilotriacetic Acid ◽  
Edta Ethylenediaminetetraacetic Acid

Three lanthanum aminopolycarboxylates [La(Hida)2(H2O)2]n·nCl·4nH2O (1), K2n[La(nta)2]n·nH2O (2) and (H2en)n[La(edta)(H2O)]2n·10nH2O (3) (H2ida = iminodiacetic acid; H3nta = nitrilotriacetic acid; H4edta = ethylenediaminetetraacetic acid; en = ethylenediamine, NH2CH2CH2NH2) have been isolated by...

A novel method for crystal control: synthesis and design of strontium carbonate with different morphologies by supported liquid membrane

2006 ◽  
Vol 39 (4) ◽  
pp. 544-549 ◽  
Author(s):  
Dong-Mei Sun ◽  
Qing-Sheng Wu ◽  
Ya-Ping Ding
Keyword(s):  
Liquid Membrane ◽  
Ethylenediaminetetraacetic Acid ◽  
Earth Metal ◽  
Nitrilotriacetic Acid ◽  
Strontium Carbonate ◽  
Supported Liquid Membrane ◽  
Control Synthesis ◽  
General Applicability ◽  
Metal Carbonates ◽  
Key Factor

A biomimetic supported liquid membrane (SLM) system was employed to control the morphology of strontium carbonate. Some interesting morphologies, including rods, shuttles and spheres, can be readily generated by using citric acid, nitrilotriacetic acid and ethylenediaminetetraacetic acid as cooperative modifiers in the mineralization process, under the conditions of pH 10, 0.01% of crystal modifier and ambient temperature. Seeking the cooperative balance of the SLM, the modifier agent and its concentration is the key factor in this system. In addition, this method was successfully applied to the morphology control of other alkaline earth metal carbonates, indicating its general applicability in materials preparation.

Sign in / Sign up

Export Citation Format

Share Document