Microbial degradation of chelating agents used in detergents with special reference to nitrilotriacetic acid (NTA)

1991 ◽  
pp. 121-132
Author(s):  
Thomas Egli ◽  
Matthias Bally ◽  
Thomas Uetz
Keyword(s):  
Special Reference ◽  
Microbial Degradation ◽  
Chelating Agents ◽  
Nitrilotriacetic Acid

scholarly journals Kinetics and Possible Mechanisms of the Ce(IV) Oxidation of EDTA, CDTA, DTPA and NTA in Perchloric Acid Media

1975 ◽  
Vol 30 (5-6) ◽  
pp. 409-415 ◽  
Author(s):  
Samir B. Hanna ◽  
William R. Cabrroll ◽  
Salem A. Attiga ◽  
William H. Webb
Keyword(s):  
Acid Concentration ◽  
Perchloric Acid ◽  
Chelating Agents ◽  
Chelating Agent ◽  
Nitrilotriacetic Acid ◽  
Stopped Flow ◽  
Tetraacetic Acid ◽  
Diethylenetriaminepentaacetic Acid ◽  
Acid Media ◽  
Oxidation Decrease

The rates of oxidation of four chelating agents with Ce(IV) in HClO4 solutions, have been studied by the stopped-flow technique. The rates first increase with increasing acidity, reach maxima which are characteristic of the chelating agent and the medium, then progressively decrease with further increasing acid concentration. At their maximum reactivities, the tendencies for oxidation decrease in the following order: trans-1,2-diaminocyclohexane tetraacetic acid (CDTA) > ethylenedinitrilotetraacetic acid (EDTA) > diethylenetriaminepentaacetic acid (DTPA) > nitrilotriacetic acid (NTA). A mechanism for the oxidation of EDTA, involving Ce4+ and Ce(OH)8+ and both unprotonated and monoprotonated chelating agent, is proposed.

scholarly journals Enhanced Degradation of Phenol by a Fenton-Like System (Fe/EDTA/H2O2) at Circumneutral pH

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 474 ◽  
Author(s):  
Selamawit Ashagre Messele ◽  
Christophe Bengoa ◽  
Frank Erich Stüber ◽  
Jaume Giralt ◽  
Agustí Fortuny ◽  
...  
Keyword(s):  
Chelating Agents ◽  
Ethylenediaminetetraacetic Acid ◽  
Chelating Agent ◽  
Nitrilotriacetic Acid ◽  
Molar Ratio ◽  
Phenol Removal ◽  
Stoichiometric Ratio ◽  
Initial Ph ◽  
Phenol Conversion ◽  
Circumneutral Ph

This work deals with the degradation of phenol based on the classical Fenton process, which is enhanced by the presence of chelating agents. Several iron-chelating agents such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriamine pentaacetic acid (DTPA), and ethylenediamine-N,N’-diacetic acid (EDDA) were explored, although particular attention was given to EDTA. The effect of the molar ligand to iron ratio, EDTA:Fe, initial pH, and temperature on the oxidation process was studied. The results demonstrate that the proposed alternative approach allows the capacity for degrading phenol to be extended from the usual acidic pH (around 3.0) to circumneutral pH range (6.5–7.5). The overall feasibility of the process depends on the concentration of the chelating agent and the initial pH of the solution. The maximum phenol conversion, over 95%, is achieved using a 0.3 to 1 molar ratio of EDTA:Fe, stoichiometric ratio of H2O2 at an initial pH of 7.0, and a temperature of 30 °C after 2 hours of reaction, whereas only 10% of phenol conversion is obtained without EDTA. However, in excess of ligand (EDTA:Fe > 1), the generation of radicals seems to be strongly suppressed. Improvement of the phenol removal efficiency at neutral pH also occurs for the other chelating agents tested.

scholarly journals Lactoferrin-catalysed hydroxyl radical production. Additional requirement for a chelating agent

1983 ◽  
Vol 210 (1) ◽  
pp. 15-19 ◽  
Author(s):  
C C Winterbourn
Keyword(s):  
Ascorbic Acid ◽  
Human Milk ◽  
Hydroxyl Radical ◽  
Ethylene Production ◽  
Chelating Agents ◽  
Chelating Agent ◽  
Nitrilotriacetic Acid ◽  
Additional Requirement ◽  
Radical Production

The ability of lactoferrin to catalyse hydroxyl radical production was determined by measuring ethylene production from methional (2-amino-4-methylthiobutyraldehyde) or 4-methylthio-2-oxobutyrate. Lactoferrin, isolated from human milk and saturated by adding the exact equivalents of Fe3+-nitrilotriacetic acid and dialysing, give little if any catalysis of the reaction between H2O2 and either O2-. or ascorbic acid at either pH 7.4 or pH 5.0. However, in the presence of chelating agents such as EDTA or nitrilotriacetic acid that can complex with lactoferrin, hydroxyl radical production by both mechanisms was observed.

Syntheses and Fe(II)/Fe(III) equilibria of the new multidentate ligands pyridine-2-phosphonic- 6-carboxylic acid and 2,6-pyridinediphosphonic acid for the use of their iron chelates as catalysts for the oxidation of H2S to S8 by air

1998 ◽  
Vol 76 (4) ◽  
pp. 445-451 ◽  
Author(s):  
Dian Chen ◽  
Arthur E Martell ◽  
Ramunas J Motekaitis ◽  
Derek McManus
Keyword(s):  
Carboxylic Acid ◽  
Chelating Agents ◽  
Sulfide Oxidation ◽  
Sodium Thiosulfate ◽  
Oxidative Degradation ◽  
Nitrilotriacetic Acid ◽  
Formation Constants ◽  
Iron Chelates ◽  
Hydrogen Sulfide Oxidation ◽  
Stepwise Formation

The syntheses of two terdentate chelating agents, pyridine-2-phosphonic-6-carboxylic acid (2PP6C) and 2,6-pyridinediphosphonic acid (2,6PDPA), are described. The stepwise stability constants for the ferric complexes at 25.0°C and μ = 0.100 M (KNO3) are log KML = 15.97 and log KML2 = 9.50 for 2PP6C, and log KML = 20.87 and log KML2 = 7.81 for 2,6PDPA. Under the same conditions the stepwise formation constants for the ferrous chelates are log KML = 8.70 and log KML2 = 5.10 for 2PP6C, and log KML = 10.12 and log KML2 = 5.33 for 2,6PDPA. The stabilities of the Fe(III) and Fe(II) chelates are high enough to prevent precipitation of Fe(OH)3 and FeS, respectively, from solutions having pH as high as 10.0. The rates of oxidative degradation of these ligands are very slow when the iron chelates are used as redox catalysts for the oxidation of H2S to S8 by air. The rates of oxidative degradation are immeasurably slow when the iron chelates are used with sodium thiosulfate as a radical scavenger.Key words: 2,6-pyridinediphosphonic acid, pyridine-2-phosphonic-6-carboxylic acid, hydrogen sulfide oxidation, oxidative degradation, nitrilotriacetic acid.

scholarly journals Formation of monoferric ovotransferrins in the presence of chelates

1976 ◽  
Vol 153 (3) ◽  
pp. 631-639 ◽  
Author(s):  
J W Donovan ◽  
R A Beardslee ◽  
K D Ross
Keyword(s):  
Differential Scanning Calorimetry ◽  
Binding Affinity ◽  
Chelating Agents ◽  
Nitrilotriacetic Acid ◽  
The Other ◽  
Scanning Calorimetry ◽  
Partially Saturated ◽  
Iron Chelating Agents

1. When ovotransferrin is partially saturated with iron, endotherms for apo-ovotransferrin, two monoferric ovotransferrins and Fe2-ovotransferrin are observed by differential scanning calorimetry. The relative sizes of the endotherms are changed in the presence of the iron-chelating agents nitrilotriacetic acid and ATP. 2. When iron is added as Fe(III)-nitrilotriacetate, at Fe-nitrilotriacetate: ovotransferrin ratios less than unity, the endotherm for Fe2-ovotransferrin is essentially absent. At Fe-nitrilotriacetate: ovotransferrin ratios of unity the only species present in solution in appreciable concentration as evidenced by their differential-scanning-calorimetry endotherms, are two monoferric ovotransferrins in approximately equal amounts. At Fe-nitrilotriacetate: ovotransferrin ratios greater than unity, the apo-ovotransferrin endotherm is absent, and the endotherms for the two monoferric ovotransferrins decrease in size as the endotherm for Fe2-ovotransferrin increases. 3. In the presence of nitrilotriacetate, binding of iron to the two sites of ovotransferrin is highly anti-co-operative, but essentially indiscriminate. When monoferric ovotransferrin is formed from apo-ovotransferrin, binding at one site is slightly favoured compared with binding at the other site, but once iron has been bound at either site, the binding affinity for iron at the unoccupied site is much decreased.

scholarly journals Chelation-Assisted Ion-Exchange Leaching of Rare Earths from Clay Minerals

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1265
Author(s):  
Georgiana Moldoveanu ◽  
Vladimiros Papangelakis
Keyword(s):  
Ion Exchange ◽  
Ammonium Sulfate ◽  
Clay Minerals ◽  
Chelating Agents ◽  
Sea Water ◽  
Cost Effective ◽  
Nitrilotriacetic Acid ◽  
Processing Route ◽  
Screening Criteria ◽  
Ethylenediaminedisuccinic Acid

The effect of biodegradable chelating agents on the recovery of rare earth elements (REE) from clay minerals via ion-exchange leaching was investigated, with the aim of proposing a cost-effective, enhanced procedure that is environmentally benign and allows high REE recovery while reducing/eliminating ammonium sulfate usage. A processing route employing a lixiviant system consisting of simulated sea water (equivalent to about 0.5 mol/L NaCl) in conjunction with chelating agents was also explored, in order to offer a process alternative for situations with restricted access to fresh water (either due to remote location or to lower the operating costs). Screening criteria for the selection of chelating agents were established and experiments were conducted to assess the efficiency of selected reagents in terms of REE recovery. The results were compared to extraction levels obtained during conventional ion-exchange leaching procedures with ammonium sulfate and simulated sea water only. It was found that stoichiometric addition of N,N′-ethylenediaminedisuccinic acid (EDDS) and nitrilotriacetic acid-trisodium form (NTA-Na3) resulted in 10–20% increased REE extraction when compared to lixiviant only, while achieving moderate Al co-desorption and maintaining neutral pH values in the final solution.

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