Hydrolysis and ammonolysis of EDTA in aqueous solution

1979 ◽  
Vol 57 (9) ◽  
pp. 1018-1024 ◽  
Author(s):  
Ramunas J. Motekaitis ◽  
David Hayes ◽  
Arthur E. Martell ◽  
Wayne W. Frenier
Keyword(s):  
Aqueous Solution ◽  
Iminodiacetic Acid ◽  
Order Rate Constant ◽  
Spectroscopic Techniques ◽  
Reaction Products ◽  
First Order ◽  
Molar Ratios ◽  
Ph Values ◽  
Rate Of Hydrolysis ◽  
Protonated Nitrogen Atom

The hydrolysis and ammonolysis of EDTA were studied in aqueous solution over a range of temperatures and at various pH values with the aid of nmr, gc, and gc – mass spectroscopic techniques. At high pH in the presence of ammonia, both ammonolysis and hydrolysis occur with the production of N-(2-aminoethyl)iminodiacetic acid (UEDDA), N-(2-hydroxyethyl)-iminodiacetic acid (HEIDA), and iminodiacetic acid (IDA) in molar ratios such that [IDA] = [UEDDA] + [HEIDA]. The first-order rate constant for the disappearance of EDTA at 175 °C in dilute aqueous ammonia is 8.6 × 10−5 s−1 whereas in the absence of ammonia its hydrolysis constant is 4.2 × 10−5 s−1. The value of ΔH0 for this reaction is approximately 35 kcal/mol. When methylamine replaces ammonia, the UEDDA is replaced by N-(2-methylaminoethyl)iminodiacetic acid. The rate of hydrolysis is increased by the presence of a tertiary amine but the latter does not become incorporated into the reaction products. A reaction mechanism is proposed involving bimolecular SN2 attack by base on a carbon atom of the ethylene bridge adjacent to a protonated nitrogen atom of EDTA with concomitant displacement of iminodiacetic acid.

Observation of a radical intermediate in the one electron oxidation of 5-methyl-1-thia-5-azacyclooctane by •Br2−

1984 ◽  
Vol 62 (9) ◽  
pp. 1874-1876 ◽  
Author(s):  
Warren Kenneth Musker ◽  
Parminder S. Surdhar ◽  
Rizwan Ahmad ◽  
David A. Armstrong
Keyword(s):  
Aqueous Solution ◽  
Rate Constant ◽  
Half Life ◽  
Cation Radical ◽  
Order Rate Constant ◽  
Type Structure ◽  
Radical Intermediate ◽  
Text Type ◽  
First Order ◽  
The One

The one electron oxidant •Br2− reacts with 5-methyl-1-thia-5-azacyclooctane (4) in aqueous solution at high pH with an overall rate constant of ~2 × 108 M s−1. The radical intermediate produced has a broad maximum at 500 nm with ε = 2400 M−1 cm−1 and at pH 10 decays with a first order rate constant of 2.3 ± 0.3 × 104 s−1, first half-life of 30 ± 5 μs. Its characteristics do not correspond to those of the [Formula: see text] species reported by Asmus and co-workers. The species appears to be the same as the cation radical reported earlier in the one electron oxidation of 4 in acetonitrile. This species is considered to have an [Formula: see text] type structure, which provides transannular stabilization.

Thermal degradation of EDTA chelates in aqueous solution

1982 ◽  
Vol 60 (10) ◽  
pp. 1207-1213 ◽  
Author(s):  
Ramunas J. Motekaitis ◽  
X. B. Cox III ◽  
Patrick Taylor ◽  
Arthur E. Martell ◽  
Brad Miles ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Thermal Degradation ◽  
Elevated Temperatures ◽  
Degradation Products ◽  
Iminodiacetic Acid ◽  
Reaction Products ◽  
Degradation Rates ◽  
Lower Temperature Range ◽  
Higher Temperature ◽  
Lower Temperature

The thermal degradation of Ca(II), Mg(II), Zn(II), Fe(II), and Ni(II) chelates of EDTA was investigated in alkaline aqueous solution at elevated temperatures (230–310 °C). The kinetics of decomposition were followed by nmr, titrimetry, and spectrophotometry. Reaction products were identified through nmr and by gas chromatography. The relative order of degradation rates, as measured by the loss of EDTA, was found to be Mg(II) > Ca(II) > Zn(II) > Fe(II) > Ni(II). The main degradation products formed in the lower temperature range (~250 °C) are iminodiacetic acid, hydroxyethyliminodiacetic acid, and ethylene glycol. Higher temperature products are primarily dimethylamine and carbon dioxide. The rates of degradation of Ca(II), Mg(II), and Zn(II) EDTA chelates are considerably enhanced when either phosphate is present or a glass-lined autoclave is employed.

THE DECOMPOSITION OF 2-METHYL-Δ2-OXAZOLINE IN AQUEOUS SOLUTION

1963 ◽  
Vol 41 (7) ◽  
pp. 1662-1670 ◽  
Author(s):  
R. Greenhalgh ◽  
R. M. Heggie ◽  
M. A. Weinberger
Keyword(s):  
Aqueous Solution ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Water Concentration ◽  
Acidity Function ◽  
First Order ◽  
Ph Values ◽  
Constant Ph ◽  
Kinetic Expression ◽  
Ph Range

Nuclear magnetic resonance has been used to follow the decomposition of aqueous solutions of 2-methyl-Δ2-oxazoline (0.29 M) at constant pH values in the range −1 to 14. The decomposition is first order with respect to total oxazoline at any specific pH, but deviates from the simple reaction of water with the protonated species above pH 5. At neutral pH values this is shown to be partially due to a second reaction involving 2-methyl-Δ2-oxazoline and O-acetylethanolamine which yields N-2-acetoxyethyl N′-2-hydroxyethyl acetamidate. The decrease in rate constant at pH < 2 is accounted for by variation in the water concentration, which is related to the acidity function. A kinetic expression is derived for the decomposition over the whole pH range studied. The decomposition of the amidate is also discussed.

scholarly journals Short Strong Hydrogen Bonds can Hinder Complex Formation: A Stability and Structure Study of Copper(II) Alkyl-N-iminodiacetic Acid Complexes in Aqueous Systems and Solid State

2021 ◽  
Author(s):  
Leif Häggman ◽  
Anders Cassel ◽  
Ingmar Persson
Keyword(s):  
Aqueous Solution ◽  
Coordination Chemistry ◽  
Solid State ◽  
Carboxylic Acid ◽  
Complex Formation ◽  
Hydrogen Bonds ◽  
Iminodiacetic Acid ◽  
Lewis Base ◽  
Polar Head ◽  
Ph Values

AbstractIn the present study the solution and coordination chemistry of copper(II)–alkyl-N-iminodiacetate systems are studied in aqueous solution by potentiometry, using ion selective copper and pH electrodes, EXAFS (extended X-ray absorption fine structure) and dye probe molecular absorption spectrophotometry. Alkyl-N-iminodiacetates with varying alkyl chain length, methyl (CH3–), n-hexyl (C6H13–), n-dodecyl (C12H25–) and n-octadecyl (C18H37–) were used to tune the amphiphilic properties of the ligands. The polar head groups have both oxygen (hard Lewis base) and nitrogen donor (border-line Lewis base) atoms. This means that metal ions with different bonding characteristics may bind these ligands differently. Furthermore, the chelating properties of the polar head group may be regulated by pH as the acid–base properties of the imine and carboxylic acid groups are different. Copper(II) forms two stable complexes with alkyl-N-iminodiacetates with short alkyl chains, present as monomers in aqueous solution, log10β1 = 11.10(2), log10β2 = 19.5(2) for methyl-N-iminodiacetate, and log10β1 = 12.22(4), log10β2 = 21.9(2) for n-hexyl-N-iminodiacetate. n-Octadecyl-N-iminodiacetic acid, present as large aggregates in acidic aqueous solution, has short strong hydrogen bonds between carboxylic acid and carboxylate groups in the surface of the aggregates, which hinder complex formation at pH values below 4, obstructs it in the pH region 4–7, while the complex formation behaves as for short-chained alkyl-N-iminodiacetates at pH > 7. The structure around copper in copper(II)–alkyl-N-iminodiacetate complexes in aqueous solution and solid state formed at different pH values and copper(II):alkyl-N-iminodiacetate ratios has been determined by EXAFS. The coordination chemistry of copper(II) shows four strong bonds in the equatorial plane, and two different Cu–O/N bond distances, ca. 0.2 Å apart, in the axial positions of a non-centrosymmetric tetragonally elongated octahedron.

scholarly journals Biosorption of Pb(II) and Zn(II) by Extracellular Polymeric Substance (Eps) of Rhizobium Radiobacter: Equilibrium, Kinetics and Reuse Studies

2013 ◽  
Vol 39 (2) ◽  
pp. 129-140 ◽  
Author(s):  
Lili Wang ◽  
Jixian Yang ◽  
Zhonglin Chen ◽  
Xiaowei Liu ◽  
Fang Ma
Keyword(s):  
Aqueous Solution ◽  
Extracellular Polymeric Substance ◽  
Kinetics Study ◽  
Order Model ◽  
Rhizobium Radiobacter ◽  
Promising Alternative ◽  
First Order ◽  
Ph Values ◽  
Polymeric Substance ◽  
Equilibrium Data

Abstract The extracellular polymeric substance (EPS) produced from Rhizobium radiobacter F2, designated as EPSF2, was investigated as a biosorbent for the removal of Pb(II) and Zn(II) from aqueous solution. The optimum biosorption pH values were 5.0 for Pb(II) and 6.0 for Zn(II). Kinetics study revealed that the biosorption followed pseudo-first-order model well, and the equilibrium data fit the Langmuir model better. The adsorbed metal ions could be effectively desorbed by HCl. Desrobed EPSF2 regained 80% of the initial biosorption capacity after five cycles of biosorption-desorption-elution. These results demonstrated that EPSF2 could be a promising alternative for Pb(II) and Zn(II) removal from aqueous solution.

Decomposition of 2-chlorophenol in aqueous solution by ultrasound/H2O2 process

1996 ◽  
Vol 33 (6) ◽  
pp. 75-81 ◽  
Author(s):  
Lin Jih-Gaw ◽  
Chang Cheng-Nan ◽  
Wu Jer-Ren
Keyword(s):  
Aqueous Solution ◽  
Organic Contaminants ◽  
Power Input ◽  
Order Reaction ◽  
Pseudo First Order Reaction ◽  
Initial Concentration ◽  
First Order ◽  
Ph Values ◽  
Cp Decomposition ◽  
Pseudo First Order

Several authors have indicated that ultrasound is effective in oxidizing organic contaminants in water and in wastewater either as the sole means of treatment or in combination with ozonation and UV irradiation. In this work we decomposed 2-chlorophenol (2-cp) in aqueous solution with ultrasound and H2O2. The experiment was conducted with a sonicator (Microson XL-2020) operated at 20 kHz. The double amplitude at the tip of the standard horn (12.7 mm) was adjusted to 0, 72 and 120 μm, corresponding to power input 0, 125 and 160 W. The initial concentration of aqueous 2-cp solution was 100 mg/l, treated in the system with 0, 100, 200 and 500 mg/l H2O2 individually. The volume of solution was 1 l in a mixing flask, and was circulated to the sonication cell at the rate 500 mL/min. Oxygen was continuously purged into the flask. The temperature of solution was kept constant at 25°C and pH was controlled at 3, 5, 7, 9 and 11. The results showed the decomposition of 2-cp was effective at increased amplitude of ultrasound and concentration of H2O2, and smaller pH. At reaction duration 360 min, 2-cp decomposition with 500 mg/l H2O2 was found with 57% improvement over the control, i.e. without H2O2 addition. The pH, controlled below the pKa of 2-cp (8.49 at 25°C), had significantly better decomposition of 2-cp than at greater values. The decomposition rate of 100 mg/l 2-cp was 99% at 120 μm double amplitude with H2O2 (200 mg/L) and pH 3, after 360 min of reaction. The removal of total organic carbon was found to be only 63%. From analysis of the experimental results, the data on 2-cp decomposition appeared to follow pseudo-first-order reaction kinetics. The squared correlation coefficient, R2, of the model was greater than 0.9 for various pH values.

Adsorption of Aniline from Aqueous Solution by KSF Montmorillonite

2011 ◽  
Vol 356-360 ◽  
pp. 208-216
Author(s):  
Jiang Ying Zhang ◽  
Jian Xu ◽  
Yuan Zhang ◽  
Lei Li ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Adsorption Process ◽  
Intraparticle Diffusion ◽  
Order Equation ◽  
Second Order ◽  
First Order ◽  
Ph Values ◽  
Whole Process ◽  
Pseudo Second Order ◽  
Pseudo First Order

In the present paper, the adsorption characteristics of aniline onto KSF montmorillonite from aqueous solution were investigated. Experiments were conducted at various pH values, temperatures, ionic strength and surfactant concentrations. Pseudo-first-order, pseudo-second-order and intraparticle diffusion models were adopted to investigate the rate parameters, and the pseudo-second-order equation was proved to be able to successfully predict whole process. Optimal adsorption pH was determined at 3.6. Among the selected models (linear, Langmuir, Freundlich, DR (Dubinin–Radusckevich) models), linear and DR models were found to be better fit the experimental data, which revealed the physisorption nature of the adsorption process. Meanwhile, with the increase of reaction temperatures, the adsorption capacity decreased. The results of the calculated thermodynamic parameters demonstrated that the adsorption was an exothermic, spontaneous and unfavorable process.

scholarly journals Kinetic Study on the Hydrolysis of p-nitrophenyl picolinate Catalyzed by g-C3N4/LaNiO3-Perovskite-type Oxides

2020 ◽  
Author(s):  
Changyu Ye ◽  
Rui Wang ◽  
Haoyu Wang ◽  
Huixing Zhang ◽  
Fubin Jiang
Keyword(s):  
Sol Gel ◽  
Order Rate Constant ◽  
X Ray Diffraction ◽  
Buffer Solution ◽  
X Ray ◽  
First Order ◽  
Ph Values ◽  
Calcination Method ◽  
Hydrolysis Of ◽  
Perovskite Type

Abstract LaNiO 3 -Perovskite-type oxides, as a novel hydrolytic catalyst, were synthesized using a sol-gel-calcination method, and were characterized by employing x-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Brunauer–Emmett–Teller (BET). It was revealed that LaNiO 3 and 2% g-C 3 N 4 /LaNiO 3 -Perovskite-type oxides are nanoparticles about 12 nm and 10nm easily agglomerated in large amounts, and the specific surface area of LaNiO 3 is 21.277 m 2 /g and 2% g-C 3 N 4 /LaNiO 3 is 26.645 m 2 /g, respectively. The results also indicate that there are irregular microporoes in the material. In the catalytic activity test, the absorption spectra were collected when hydrolysis of p-nitrophenyl picolinate (PNPP) (C PNPP =1-5×10 -5 mol/L) was catalyzed by LaNiO 3 (0.5g/L) and 2% g-C 3 N 4 /LaNiO 3 (0.5g/L) in buffer solution at different pH values (6.5-7.8), respectively. Based on the absorption spectrum data, the pseudo first-order rate constant is estimated to be 0.59min -1 and 1.14min -1 , respectively. In addition, the proposed kinetics model of this reaction was confirmed by the results of the spectrum and the calculations.

Studies on sorption of cadmium (II) ions onto Haro river sand from aqueous media using radiotracer and voltammetric techniques

2006 ◽  
Vol 94 (8) ◽  
Author(s):  
Riaz Ahmed ◽  
Tayyaba Yamin ◽  
Muhammad S. Ansari ◽  
Syed Moosa Hasany
Keyword(s):  
Aqueous Media ◽  
Kinetic Studies ◽  
Order Rate Constant ◽  
River Sand ◽  
Radiotracer Technique ◽  
First Order ◽  
Ph Values ◽  
Voltammetric Techniques ◽  
Effects Of Ph ◽  
Intra Particle Diffusion

SummarySorption of Cd(II) ions on Haro river sand has been studied using radiotracer technique. The effects of pH and acid concentrations on the sorption were studied. The sorption increases with pH, reaches a maximum at pH7 and decreases at higher pH values. With acids, it was found that sorption decreases with increasing acid concentration, and for more oxidizing acids sorption was less. Kinetic studies indicate that mostly intra particle diffusion occurs with first order rate constant of 18.45 × 10

The iron(III)-catalyzed oxidation of EDTA in aqueous solution

1980 ◽  
Vol 58 (19) ◽  
pp. 1999-2005 ◽  
Author(s):  
Ramunas J. Motekaitis ◽  
Arthur E. Martell ◽  
David Hayes ◽  
Wayne W. Frenier
Keyword(s):  
Aqueous Solution ◽  
Elevated Temperatures ◽  
Iminodiacetic Acid ◽  
Nitrilotriacetic Acid ◽  
Similar Reaction ◽  
Reactive Intermediate ◽  
Reaction Products ◽  
Reaction Proceeds ◽  
Catalyzed Oxidation ◽  
By Products

At temperatures above 100 °C iron(III) oxidizes coordinated EDTA to ethylenediaminetriacetic acid in aqueous solution in the absence of molecular oxygen. The reaction proceeds with an activation energy of 28.6 kcal/mol, and its rate is directly proportional to the concentration of Fe(III) and inversely proportional to pH. At 125 °C, the halflife of Fe(III) in the presence of excess EDTA is about 3 h at pH 9.3, but increases to >70 h at pH 5.4. The reaction is stoichiometric and no other reaction products or by-products were detected by nmr, gc, and gc – mass spectroscopy. In the presence of oxygen iron catalyzes quantitative oxidation of ethylenediamine-N,N,N′,N′-tetraacetic acid (EDTA) to ethylenediaminetriacetic acid. The copper(II)–EDTA chelate undergoes a similar reaction but higher temperatures [Formula: see text] are required. Iron(III) also oxidizes nitrilotriacetic acid (NTA) to iminodiacetic acid (IDA) and glycine. The hydrolyzed species Fe(OH)EDTA is shown to be the reactive intermediate, and the well-known (Fe–EDTA)2O4− μ-oxo dimer is shown not to exist at elevated temperatures (above 100 °C). Probable mechanisms are proposed for these reactions and comparisons are made with earlier work.

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