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.

One-Pot Synthesis of Coral-Shaped Gold Nanostructures for Surface-Enhanced Raman Scattering

2011 ◽  
Vol 14 ◽  
pp. 47-55 ◽  
Author(s):  
Jian Hui Yang ◽  
Dhiraj K. Sardar
Keyword(s):  
Raman Scattering ◽  
Ethylenediaminetetraacetic Acid ◽  
Chelating Agent ◽  
Surface Enhanced Raman Scattering ◽  
Gold Nanostructures ◽  
Molar Ratio ◽  
One Pot ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

In this work, a chelating agent, ethylenediaminetetraacetic acid (EDTA) was used for the controllable synthesis of gold nanostructures in aqueous solution. Coral-shaped Au nanostructures were synthesized by reducing HAuCl4 with EDTA. EDTA serves not only as a reducing agent but also as a particle capping agent in the formation of coral-shaped Au nanostructures. It is found that the molar ratio of HAuCl4:EDTA and reacted temperature play significant effects on the formation and growth of these novel nanostructures. These Au nanostructures could serve as highly sensitive and reproductive surface-enhanced Raman scattering (SERS) substrates for chemical and biological detection.

scholarly journals Characterization, Dissolution, and Solubility of Lead Hydroxypyromorphite [Pb5(PO4)3OH] at 25–45°C

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Yinian Zhu ◽  
Zongqiang Zhu ◽  
Xin Zhao ◽  
Yanpeng Liang ◽  
Yanhua Huang
Keyword(s):  
Molar Ratio ◽  
Stoichiometric Ratio ◽  
Ultrapure Water ◽  
Solution Ph ◽  
Free Energy Of Formation ◽  
Initial Ph ◽  
Naoh Solution ◽  
Water Ph ◽  
Ft Ir ◽  
Sem Analyses

Dissolution of the hydroxypyromorphite [lead hydroxyapatite, Pb5(PO4)3OH] in HNO3solution (pH = 2.00), ultrapure water (pH = 5.60), and NaOH solution (pH = 9.00) was experimentally studied at 25°C, 35°C, and 45°C. The XRD, FT-IR, and FE-SEM analyses indicated that the hydroxypyromorphite solids were observed to have indistinguishable change during dissolution. For the hydroxypyromorphite dissolution in aqueous acidic media at initial pH 2.00 and 25°C, the aqueous phosphate concentrations rose quickly and reached the peak values after 1 h dissolution, while the aqueous lead concentrations rose slowly and reached the peak values after 1440 h. The solution Pb/P molar ratio increased constantly from 1.10 to 1.65 near the stoichiometric ratio of 1.67 to 209.85~597.72 and then decreased to 74.76~237.26 for the dissolution at initial pH 2.00 and 25°C~45°C. The averageKspvalues for Pb5(PO4)3OH were determined to be 10−80.77(10−80.57−10−80.96) at 25°C, 10−80.65(10−80.38−10−80.99) at 35°C, and 10−79.96(10−79.38−10−80.71) at 45°C. From the obtained solubility data for the dissolution at initial pH 2.00 and 25°C, the Gibbs free energy of formation [ΔGfo] for Pb5(PO4)3OH was calculated to be −3796.71 kJ/mol (−3795.55~−3797.78 kJ/mol).

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 A Comparison of the Role of the Chelating Agent on the Structure of Lithium Conducting Solid Electrolyte Li1.4Al0.4Ti1.6(PO4)3: Pechini vs. Modified Pechini-Type Methods

Batteries ◽  
2020 ◽  
Vol 6 (4) ◽  
pp. 48
Author(s):  
Mohammad Reza Ghaani ◽  
Amir Masoud Mohtasebi ◽  
Razie Tajeri ◽  
Pirooz Marashi
Keyword(s):  
Citric Acid ◽  
Metal Ions ◽  
Electrochemical Impedance ◽  
Ethylenediaminetetraacetic Acid ◽  
Lithium Ion ◽  
Simultaneous Thermal Analysis ◽  
Chelating Agent ◽  
Molar Ratio ◽  
Complexing Agent ◽  
Solution Ph

In recent years, solid lithium-ion conductors have been widely studied because of their applications as electrodes and solid electrolytes in rechargeable lithium-ion batteries. Citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) were employed to synthesize the nanostructured NASICON-type Li1.4Al0.4Ti1.6(PO4)3 ceramic. The chelating agent, together with an ethylene glycol (EG) and the esterification agent were employed to form a network decorated with uniform dispersed metal ions under specific conditions: molar ratio [complexing agent/metal ions] = 1 and the molar ratio [EG/EDTA] = 6, whereas the solution pH was kept below 1. A well crystalline NASICON structure was formed following the heat treatment of the produced gel at 630 °C. Simultaneous thermal analysis (STA) revealed lower required temperature for pyrolysis and crystallization using EDTA. Powder X-ray diffraction (PXRD) showed the formation of larger crystallite size when citric acid was employed. The data from scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) have confirmed the higher apparent porosity and a larger proportion of grain boundaries in the case of EDTA-assisted synthesis.

Evaluation of Rock Mechanical Properties Alteration During Matrix Stimulation With Chelating Agents

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Assad Barri ◽  
Mohamed Mahmoud ◽  
Salaheldin Elkatatny
Keyword(s):  
Mechanical Properties ◽  
Elastic Properties ◽  
Carbonate Rocks ◽  
Chelating Agents ◽  
Ethylenediaminetetraacetic Acid ◽  
Chelating Agent ◽  
Well Stimulation ◽  
Before And After ◽  
Rock Mechanical Properties ◽  
Carbonate Formations

Well stimulation using acidic solutions is widely used to treat carbonate formations. The acidic fluids remove the near-wellbore damage and create channels around the wellbore by dissolving fraction of the carbonate rocks. Many stimulation fluids have been used such as hydrochloric acid (HCl) acid, organic acids, and chelating agents to stimulate carbonate reservoirs. Wormholes that are created by these fluids are very effective and will yield negative skin values and this will enhance the well productivity. In addition to the wormhole creation, the diffusion of these fluids inside the pores of the rock may create significant and permanent changes in the rock mechanical properties. These changes can eventually lead to weakening the rock strength, which may lead to future formation damage due to the wellbore instability. In this paper, the effect of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) chelating agents on the carbonate rocks elastic properties was investigated. The effect of wormholes created by chelating agent on the rock mechanical properties was investigated. Computed tomography (CT) scan and acoustic measurements were conducted on the core samples before and after matrix stimulation treatments. Experimental results showed that the mechanical properties of strong rocks such as Indiana limestone (IL) cores were not affected when chelating agents were used to stimulate those cores. On the other hand, less strong rocks such as Austin chalk (AC) show significant alteration on the rock elastic properties when chelating agents were used as stimulation fluids.

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 Synthesis and Characterization ofLiNiO2Nanopowder with Various Chelating Agents

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Mehrdad Balandeh ◽  
Sirous Asgari
Keyword(s):  
Particle Size ◽  
Intensity Ratio ◽  
Metal Ion ◽  
Chelating Agents ◽  
Average Particle Size ◽  
Chelating Agent ◽  
Molar Ratio ◽  
Average Particle ◽  
Tem Analysis ◽  
Transmission Electron

LiNiO2powders were synthesized with acrylic acid, citric acid, oxalic acid, and triethanolamine (TEA) as a chelating agent. CrystallizedLiNiO2was synthesized in air at a calcinations temperature of 500∘Cfor 12 hours, when the molar ratio of chelating agents to total metal ion (RPM) was 1.0. The TEA-assisted method had the highest intensity ratio of (003)/(104) peaks of X-ray diffraction (XRD) spectrum. The transmission electron microscopy (TEM) analysis indicates that the sample prepared with triethanolamine obtained the smallest particle size with average particle size of only 12 nm. The results indicate that chelating agents have an important role in the intensity ratio of (003)/(104) peaks of XRD spectrum, size and shape of powders.

scholarly journals Iron-[S,S′]-EDDS (FeEDDS) Chelate as an Iron Source for Horticultural Crop Production: Marigold Growth and Nutrition, Spectral Properties, and Photodegradation

HortScience ◽  
2011 ◽  
Vol 46 (8) ◽  
pp. 1148-1153 ◽  
Author(s):  
Joseph P. Albano
Keyword(s):  
Spectral Properties ◽  
Crop Production ◽  
Chelating Agents ◽  
Ethylenediaminetetraacetic Acid ◽  
Free Ligand ◽  
Chelating Agent ◽  
Dry Weight ◽  
Structural Isomer ◽  
Horticultural Crops ◽  
Significant Difference

Aminopolycarboxylic acid (APCA) complexones, commonly referred to as ligands or chelating agents, like ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), are commonly used in soluble fertilizers to supply copper (Cu), iron (Fe), manganese (Mn), and/or zinc (Zn) to plants. Offsite runoff and contamination of surface waters with these chelating agents is of increasing concern as a result of their reported ability to remobilize heavy metals in sediments and their low susceptibility to biodegradation. The APCA ethylenediaminedisuccinic acid (EDDS) is a structural isomer of EDTA with the [S,S′] stereoisomer of the complexone, a compound naturally produced by actinomycetes, and is biodegradable. Information on the use of [S,S′]-EDDS as a chelating agent in formulating soluble fertilizers for the production of horticultural crops is limited. Therefore, a series of studies were conducted with the objectives of evaluating Fe[S,S′]-EDDS as an Fe-chelate fertilizer agent in the production of marigold and [S,S′]-EDDS (free ligand) and/or Fe[S,S′]-EDDS spectral properties and vulnerability to photodegrdation. Marigold grown in peat-based media were fertilized with complete nutrient solution containing 1 mg·L−1 Fe from FeEDDS, FeEDTA, or FeDTPA. There was no significant difference in foliar Fe or Mn between Fe-chelate treatments, averaging 140 μg·g−1 and 88 μg·g−1, respectively, nor were there significant differences in leaf dry weight (2.30 g) between Fe treatments. Spectra of [S,S′]-EDDS and Fe[S,S′]-EDDS produced from ferrous or ferric sources of Fe absorbed maximally in the 210 to 230 nm and 238 to 240-nm range, respectively. The [S,S′]-EDDS complexone used in the current study, a 30% assay solution, had chromaphoric properties, appearing light yellow in color. When exposed to light, Fe[S,S′]-EDDS quickly degraded at a rate at least twice that of FeEDTA.

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).

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