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.

scholarly journals Studies on the mechanism of chelate degradation in iron-based, liquid redox H2S removal processes

1995 ◽  
Vol 73 (2) ◽  
pp. 264-274 ◽  
Author(s):  
Dian Chen ◽  
Arthur E. Martell ◽  
Derek McManus
Keyword(s):  
Hydroxyl Radical ◽  
Chelating Agents ◽  
Oxidative Degradation ◽  
Chelating Agent ◽  
Side Reaction ◽  
Nitrilotriacetic Acid ◽  
Carboxylate Groups ◽  
Removal Processes ◽  
S Oxidation ◽  
Trapping Agent

Available data on the oxidation of nitrilotriacetic acid (NTA), ethylenedinitrilotetraacetic acid (EDTA), N-hydroxyethylethylenediaminetriacetic acid (HEDTA), and other aminopolycarboxylate chelating agents are reviewed and the intermediates and products of the oxidative degradation of each chelating agent are described and compared. The oxidation of these chelating agents occurs during the reoxidation of the ferrous chelate to the ferric chelate, during which a Fenton type side reaction occurs in which hydrogen peroxide is formed and which in turn generates the hydroxyl radical by reaction with ferrous ion. The site of oxidative attack by the hydroxyl radical on these ligands seems to be the -CH2- groups α to the carboxylate groups, as well as the -CH2- groups in the ethylene bridges between the nitrogens. The evidence for the implication of the hydroxyl radical as the active oxidant is discussed, and the use of phenyl-tert-butylnitrone (PBN) as the trapping agent for the hydroxyl radical is described. The use of chelating agents as Fe3+/Fe2+ redox catalysts for the oxidation of H2S to sulfur that are less reactive toward the hydroxyl radical is recommended. Keywords: chelate degradation, H2S oxidation, nitrilotriacetic acid (NTA), ethylenedinitrilotetraacetic acid (EDTA), N-hydroxyethylethylenediaminetriacetic acid (HEDTA).

scholarly journals Study on the Behavior and Removal of Cadmium and Zinc Using Taraxacum officinale and Gazania under the Application of Biodegradable Chelating Agents

2021 ◽  
Vol 11 (4) ◽  
pp. 1557
Author(s):  
Naoki Kano ◽  
Takumi Hori ◽  
Haixin Zhang ◽  
Naoto Miyamoto ◽  
David Eva Vanessa Anak ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Chelating Agents ◽  
Environmental Control ◽  
Chelating Agent ◽  
Taraxacum Officinale ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
Experimental Treatments ◽  
The One

The removal of cadmium (Cd) and zinc (Zn) from soil by phytoremediation was investigated using Taraxacum officinale and Gazania. A plant environmental control system was used to cultivate the plants. The effects of different biodegradable chelating agents (i.e., EDDS, HIDS, and GLDA), relative humidity, and other competitive metals on the adsorption of Cd and Zn were also studied. In addition, the approach for metal recovery was explored by extraction of metals from plants after phytoremediation using Gazania. The concentrations of Cd and Zn were determined by inductively coupled plasma mass spectrometry (ICP-MS). In addition, one-way analysis of variance (ANOVA) tests were performed.to determine significant differences between the experimental treatments adopted in this work. Consequently, the following main conclusions were obtained: (1) In the case of Taraxacum officinale, Cd and Zn could be removed even under the presence of other heavy metals. (2) By adding a chelating agent, the amount absorbed by the shoot generally increased. (3) In the case of Gazania, the concentration of Cd was higher in root than that in shoot, whereas the concentration of Zn was higher in the shoot than that in the root. (4) Taraxacum officinale was more suitable for phytoremediation of Cd than Gazania. (5) Cd and Zn could be extracted from plants by adding a low concentration of nitric acid. (6) The one-way ANOVA tests showed no statistically significant differences among the experimental treatments.

scholarly journals Effect of chelating agents on removal of 137Cs from contaminated soil

2018 ◽  
Vol 15 (35) ◽  
pp. 158-168
Author(s):  
Firas M. Radhi
Keyword(s):  
Removal Efficiency ◽  
Contaminated Soil ◽  
Chelating Agents ◽  
Soil Samples ◽  
Coarse Grained ◽  
Tetraacetic Acid ◽  
Mixing Ratio ◽  
Soil Mixing ◽  
Chemical Washing ◽  
Washing Method

In the present research, the chemical washing method has been selected using three chelating agents: citric acid, acetic acid and Ethylene Diamine Tetraacetic Acid (EDTA) to remove 137Cs from two different contaminated soil samples were classified as fine and coarse grained. The factors that affecting removal efficiency such as type of soil, mixing ratio and molarity have been investigated. The results revealed that no correlation relation was found between removal efficiency and the studied factors. The results also showed that conventional chemical washing method was not effective in removing 137Cs and that there are further studies still need to achieve this objective.

scholarly journals Chelating agent and substrate effect on hydrothermal growth of Yb3+/Er3+ doped NaYf4 film

2021 ◽  
Vol 15 (1) ◽  
pp. 69-78
Author(s):  
Suman Duhan ◽  
Kedar Sahoo ◽  
Ahmad Imteyaz ◽  
Sudhir Singh ◽  
Manoj Kumar
Keyword(s):  
Crystal Growth ◽  
Hydrothermal Method ◽  
Luminescence Intensity ◽  
Chelating Agents ◽  
Chelating Agent ◽  
Upconversion Emission ◽  
Substrate Effect ◽  
Current Investigation ◽  
One Step ◽  
Film Roughness

We report simultaneous crystal growth and deposition of upconverting Yb3+/Er3+ doped NaYF4 film (UCF) on conducting and non-conducting substrates by one-step hydrothermal method. The characteristics such as film topography, morphology, crystallographic phase and upconverting luminescence intensity were found to depend both on the chelating agent and nature of the substrate. The characteristics of the prepared films varied interestingly when either the chelating agent or the substrate was changed. The upconversion emission intensities were found to increase with decreasing film roughness. Further, current investigation demonstrated that the NaYF4 films deposited using EDTA or DTPA chelating agents on ITO substrate and EGTA chelating agent on PG substrate were more uniform and resulted in greater upconverted emission intensities. We envision plausible use of current technology in the development of affordable optical platforms for several optoelectronic applications.

Effect of EDTA and EDDS on Phytoremediation of Pb- and Zn- Contaminated Soil by Brassica Juncea

2012 ◽  
Vol 518-523 ◽  
pp. 5040-5046 ◽  
Author(s):  
Li Di Gao ◽  
Naoki Kano ◽  
Yuichi Sato ◽  
Shuang Zhang ◽  
Hiroshi Imaizumi
Keyword(s):  
Heavy Metals ◽  
Control System ◽  
Plant Growth ◽  
Brassica Juncea ◽  
Contaminated Soil ◽  
Chelating Agents ◽  
Environmental Control ◽  
Chelating Agent ◽  
Whole Plant ◽  
Biomass Loss

Effect of EDTA and EDDS on phytoremediation of Pb- and Zn- contaminated soil by Brassica Juncea was investigated in this work. Especially, the effect of the kind and the method of adding chelating agent was investigated during the plant growth. Plants were grown in an environmental control system. The biomass of the whole plant was weighed, and the uptake of Pb and Zn in shoot and root were determined using ICP-AES. Consequently, the following matters have been obtained: (1) Both EDTA and EDDS significantly enhanced the translocation of metals (Pb and Zn) in soil from root to shoot. Furthermore, the two chelating agents resulted in a sharply biomass loss for more than 30% of the control. As a result, the total uptake amount of metals by Brassica Juncea was decreased (except the uptake of Pb with the addition of 3.0 mmol•kg-1 EDTA). (2) EDDS showed the higher inhibition for the growth of Brassica Juncea than EDTA. (3) The method for adding EDTA and EDDS at several times separately did not necessarily increase the uptake of heavy metals.

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