Ethylenediaminetetraacetic Acid Complex Research Articles

Application of Fe-ethylene diamine tetraacetic acid complex to enhance the electrocatalytic activation of peroxymonosulfate under neutral pH condition for removal of refractory naphthenic acids

In this work, ethylene diamine tetraacetic acid (EDTA) was applied as a chelating agent to stabilize Fe(III)/Fe(II) cycle to effectively activate peroxymonosulfate (PMS) in an electrochemical (EC) co-catalytic system for elimination of naphthenic acids (NAs) under neutral pH condition. 1-Adamantanecarboxylic acid (ACA) was applied as the model compound for NAs that are persistent contaminants in petroleum industrial wastewater. In the PMS/EC/Fe(III)-EDTA system, complete removal of ACA has been achieved in 20-min reaction under neutral pH condition. Degradation mechanisms were investigated via electron paramagnetic resonance (EPR) analysis, probe experiments and quenching experiments to reveal the reactive species •OH, SO4•− and 1O2 for ACA removal, the production of which have been significantly facilitated by the introduction of EDTA complex. A new pathway has been found for the production of 1O2 via several intermediates including hydrogen peroxide and superoxide radicals. Density functional theory (DFT) calculations and mass spectrometry analysis were applied to predict ACA degradation pathways and byproducts. Decarboxylation, hydroxyl substitution and carbonyl substitution byproducts of ACA were detected. The PMS/EC/Fe(III)-EDTA system suffered nonimportant influence at the presence of humic acid, H2PO4-, HCO3–, NO3– and Cl- for ACA removal. Overall results demonstrate the effectiveness and reliability of the PMS/EC/Fe(III)-EDTA system for efficient removal of NAs in petroleum wastewater in natural environment under neutral pH condition.

Regulating the distribution of phosphorus in sewage sludge hydrothermal carbonization products by complexation pretreatment

In this study, we investigated the effects of the concentrations of four pretreatment complexing reagents, namely ascorbic acid (AS), citric acid (CA), N, N-bis (carboxymethyl) glutamic acid (GLDA), and ethylenediaminetetraacetic acid (EDTA), on the phosphorus contents and forms in hydrothermally carbonized sludge products. The results showed that among the four complexing reagents, EDTA had the greatest effect on the phosphorus transfer from the solid phase to the liquid phase during the hydrothermal process of the sludge, followed, respectively, by GLDA, CA, and AS. The phosphorus proportion of the liquid phase was 63.96% under hydrothermal process temperature, reaction time, and EDTA concentration of 160 °C, 60 min, and 0.2 mol/L, respectively. The results showed formations of EDTA complexes with Ca, Fe, and Al in the sludge, releasing phosphorus bound to the metal ions into the liquid phase. The highest total phosphorus concentration in the liquid phase was 2533.31 mg/L following the increase in the hydrothermal process temperature from 100 to 160 °C. However, the Fe and Al-EDTA complexes were thermally decomposed after continuously increasing the hydrothermal process temperature to 240 °C, resulting in a readsorption of phosphorus to the solid phase with Fe, Al, and other metals and, consequently, decreasing the phosphorus content to 880.93 mg/L in the liquid phase. The results of this study provide a scientific basis for regulating phosphorus distribution in the solid and liquid phases of hydrothermally carbonized sludge products and effectively recovering phosphorus in the liquid phase.

Redox property of coordinated iron ion enables activation of O2 via in-situ generated H2O2 and additionally added H2O2 in EDTA-chelated Fenton reaction

The Fenton system was a generation system of reactive oxygen species via the chain reactions, which employed H2O2 and O2 as radical precursors and Fe2+/Fe3+ as electron-donor/acceptor for triggering or terminating the generation of radicals. Recent work mainly emphasized the Fe2+- activated H2O2 and the application of in-situ generated •OH, while neglecting other side-reactions. In this work, EDTA (Ethylene diamine tetraacetic acid) was employed as a chelating agent of iron ions, which simultaneously changed the redox property of coordinated iron. The Fe2+-EDTA complexes in the presence of dissolved oxygen enabled the two-electron transfer from Fe2+ to O2 and the in-situ production of H2O2, which further activate H2O2 for yielding •OH. Meanwhile, coordinated Fe3+ exhibited non-negligible reactivity toward H2O2, which was higher than that of free Fe3+ in the traditional Fenton system. The complexation of EDTA with Fe3+ could enhance the Fe2+ generation reaction by the H2O2, accompanied by the O2•− formation. The enhancement of O2•− formation and Fe2+-EDTA regeneration induced the subsequent H2O2 activation by Fe2+-EDTA, thus accelerating the Fe3+-EDTA/Fe2+-EDTA cycle for simultaneously producing O2•− and •OH. To sum up, the EDTA-chelated Fenton system extended the applicable pH range to circumneutral/alkaline level and tuned the redox property of coordinated iron for diversifying the •OH production routes. The research reinterpreted the chain reactions in the Fenton system, revealing another way to enhance the radical production or other property of the Fenton/Fenton-like system.

Calcium aluminate phosphor-containing mortar achieved via aqueous metal-ethylenediaminetetraacetic acid complex solution and high-heat treatment

Calcium aluminate phosphors were synthesized on mortar substrates using an aqueous solution comprising metal (Al,Eu,Nd)-ethylenediaminetetraacetic acid (EDTA) complexes, followed by treatment with a high-heat hydrogen/oxygen (H2-O2) coupled flame with a variable gas flow rate. The infrastructure functionalizationperformance of the cement system was evaluated through crystal structure analysis and emission/excitation properties investigation. The emission phase of the calcium aluminates was identified using cathodoluminescence microscopy. The afterglow properties were also investigated. Furthermore, a model for the formation of calcium-aluminate phosphors using a metal-EDTA aqueous solution with H2-O2 flame treatment was developed.

LANTHANIDE CONTRACTION IN CHELATES OF ETHYLENEDIAMINETETRAACETIC ACID BASED ON CRYSTALLOGRAPHIC DATA: A SHORT REVIEW

The lanthanide (Ln) series has been attracted so much attention not only for its physical properties but also for its applications in organic synthesis and biomedical engineering. In the lanthanide chemistry, lanthanide contraction is a crucial concept meaning the gradual decrease in ionic radii as the atomic number of the Ln series increases. As a prominent chelator, ethylenediaminetetraacetic acid (EDTA) has been well-known to give stable complexes with various metals including Ln ions, resulted in forming (EDTA−4H)4− anion by deprotonation; over 100 kinds of Ln-EDTA complexes have hitherto been synthesized and structurally characterized using X-ray crystallography. While the lanthanide contraction phenomenon has been extensively studied in certain complexes of Ln, systematization on the Ln-EDTA remains inadequate though the chelates of EDTA are commonly used. Thus, this study presents a comprehensive analysis based on the data from the Cambridge Crystallographic Data Centre (CCDC). In mononuclear EDTA complexes X[Ln(EDTA−4H)(H2O)m]·nH2O (X+ = NH4+and its analogues) systematic lanthanide contraction depending on their coordination number are presented except for a few cases. However, in the case of non-mononuclear complexes or coordination polymers, the compositions become more complicated, and a greater variation in atomic bond length occurs, which is unusual for the lanthanide contraction studies in previous research. These varieties are considered to be influenced by different types of counter-cations, inorganic anions, solvent molecules and bridging O atoms from another EDTA anions. This suggests the flexibility and versatility of EDTA as a ligand. Such findings in the Ln-EDTA complexes could potentially provide us further development of a novel function in the future.

Effects of EDTA on the leaching behaviors of Cs(I) and Co(II) from cement waste forms

Cementation is extensively employed for immobilizing radionuclides in low- and intermediate-level radioactive wastes generated during the decommissioning of nuclear power plants. Ethylenediaminetetraacetic acid (EDTA), used as a decontamination agent during the decommissioning process, can be introduced into the cement waste form containing radionuclides. This study investigated the effects of the EDTA present in simulated radioactive decommissioning wastes on the leaching behaviors of Co and Cs immobilized in the cement waste form. Co leaching was facilitated by the formation of highly mobile Co–EDTA complexes. However, Cs leaching was impeded by the competition for leaching with other metal–EDTA complexes. Moreover, the EDTA-induced carbonated layer with a dense pore structure played a crucial role as a retardation barrier for the Cs leaching. The calcite contents of the samples with 8 wt% EDTA were approximately three times higher than those of the samples without EDTA. The introduced EDTA affected the leaching behaviors of both Co and Cs, as well as the microstructure evolution of the cement waste form. Nevertheless, the addition of EDTA had a relatively low positive effect on the efficiency of Cs immobilization, but also an obvious negative effect on the efficiency of Co immobilization, regardless of the concentration of EDTA. Finally, an EDTA dosage of 1 wt% in the cement waste forms containing Co or Cs is suggested as a potential waste acceptance criterion for solidified low- and intermediate-level radioactive waste.

Development and Comparative Evaluation of Two Highly Sensitive Immunosensor Platforms for Trace Determination of Copper Ions in Drinking Water Using a Monoclonal Antibody Specific to Copper-EDTA Complex.

This study describes the development of two highly sensitive immunosensor platforms for the trace determination of copper ions, Cu(II), in drinking water. These platforms were a microwell-based enzyme-linked immunosorbent assay (ELISA) and a kinetic exclusion assay (KinExA) with a KinExATM 3200 immunosensor. Both ELISA and KinExA were developed utilizing the same antibody and coating reagent. The antibody was a mouse monoclonal antibody, designated as 8D66, that specifically recognized Cu(II)-ethylenediamine tetraacetic acid complex (Cu(II)-EDTA) but did not recognize Cu(II)-free EDTA. The 8D66 monoclonal antibody was generated by the fusion of spleen cells of an immunized BALB/c mouse with SP2/0-Ag14 myeloma cells. The immunogen was a protein conjugate of Cu(II)-EDTA with keyhole limpet hemocyanin protein. The coating reagent was Cu(II)-EDTA covalently linked to bovine serum albumin protein (Cu(II)-EDTA-BSA). Both assays involved the competitive binding reaction between Cu(II)-EDTA complexes, formed in the sample solution, and Cu(II)-EDTA-BSA conjugate which has been immobilized onto ELISA plates (in ELISA) or polymethylmethacrylate beads (in KinExA) for a limited quantity of binding sites of the 8D66 antibody. In ELISA, color signals were generated by a peroxidase-labeled secondary antibody and 3,3',5,5'-tetramethylbenzidine substrate. In KinExA, a fluorescein isothiocyanate-labeled secondary antibody was used to generate KinExAgram (trend-line fluorescence responses vs. time). The conditions of both ELISA and KinExA were investigated, and the optimum procedures were established. Both ELISA and KinExA were validated, and all validation parameters were acceptable. Many different metal ions that are commonly encountered in drinking water did not interfere with the Cu(II) analysis by both ELISA and KinExA. Both assays were applied to the determination of Cu(II) in drinking water with satisfactory accuracy and precision. Both assays were compared favorably with inductively coupled plasma atomic emission spectroscopy in terms of their abilities to accurately and precisely determine Cu(II) in drinking water samples. A comparative evaluation of ELISA and KinExA revealed that KinExA had a higher sensitivity and better precision than ELISA, whereas both assays had comparable accuracy. Both ELISA and KinExA were superior to the existing atomic spectrometric methods for Cu(II) in terms of sensitivity, convenience, and analysis throughputs. The proposed ELISA and KinExA are anticipated to effectively contribute to assessing Cu(II) concentrations and control the exposure of humans to its potential toxicities.

Selective abatement of electron-rich organic contaminants by trace complexed Mn(II)-catalyzed periodate via high-valent manganese–oxo species

Mn(II) is among the most efficient catalysts for the periodate (PI)-based oxidation process. In-situ formed colloidal MnO2 simultaneously serves as the catalyst and oxidant during the degradation of organic contaminants by PI. Here, it is revealed that the complexation of Mn(II) by ethylene diamine tetraacetic acid (EDTA) further enhances the performance of PI-based oxidation in the selective degradation of organic contaminants. As evidenced by methyl phenyl sulfoxide probing, 18O-isotope labeling, and mass spectroscopy, EDTA complexation modulates the reaction pathway between Mn(II) and PI, triggering the generation of high-valent manganese–oxo (MnV–oxo) as the dominant reactive species. PI mediates the single-electron oxidation of Mn(II) to Mn(III), which is stabilized by EDTA complexation and then further oxidized by PI via the oxygen-atom transfer step, ultimately producing the MnV–oxo species. Ligands analogous to EDTA, namely, [S,S]-ethylenediaminedisuccinic acid and L-glutamic acid N,N-diacetic acid, also enhances the Mn(II)/PI process and favors MnV–oxo as the dominant species. This study demonstrates that functional ligands can tune the efficiency and reaction pathways of Mn(II)-catalyzed peroxide and peroxyacid-based oxidation processes.

Binding Pocket Response of EDTA Complexes with Alkaline Earth Dications to Stepwise Hydration─Structural Insight from Infrared Spectra.

We investigate the microhydration structures of complexes of alkaline earth dications and ethylenediaminetetraacetic acid (EDTA) for up to two water molecules, using cryogenic ion vibrational spectroscopy in concert with density functional theory (DFT). The interaction with water shows a clear dependence on the chemical identity of the bound ion. For Mg2+, microhydration mostly involves the carboxylate groups of EDTA and does not entail direct contact with the dication. In contrast, the larger ions (Ca2+, Sr2+, and Ba2+) interact electrostatically with the microhydration environment, and this interaction increases in importance with the size of the ion. This trend reflects the ion position in the EDTA binding pocket, which comes closer to the rim of the pocket with increasing ion size.

Investigation of the morphologies of chelate flame-sprayed metal oxide splats

This paper reports an investigation of Er2O3 splats formed by metal–ethylenediaminetetraacetic acid (EDTA) complex particles that were applied onto aluminum alloy substrates by flame spraying. The splat morphologies and coating microstructures were analyzed under different conditions. The effects of the in-flight particle temperature of the carrier gases and the impact particle deposition temperature on solidification of the molten droplets were evaluated with a rotating dodecahedron stage operated at velocities of 30, 75, and 90 rpm and with different temperatures and angles of incidence. Various techniques were used to analyze the surfaces and cross sections of the splats and coatings formed under the different conditions. Most of the splats underwent transitions from disk shapes (ratio > 85 %) to irregular shapes (circularity of 0.61–0.80) with increasing rotational velocity. The spray process provided a coating with a porosity of 23.3 % at a powder flow rate of 20 g/min. The temperature reached during the chelate flame spraying (CFS) process and the condensing velocity of the deposited splat, rather than the in-flight particle temperature, were found to control the splat morphology. This synergistic condensation effect paves the way to successful deposition of high-temperature structural ceramic coatings such as Er2O3 with the CFS method.

Influence of Transition Metal Electron Configuration on the Structure of Metal–EDTA Complexes

The vibrational spectra of cold complexes of ethylenediaminetetraacetic acid (EDTA) with transition metal dications in vacuo show how the electronic structure of the metal provides a geometric template for interaction with the functional groups of the binding pocket. The OCO stretching modes of the carboxylate groups of EDTA serve as structural probes, informing on the spin state of the ion as well as the coordination number in the complex. The results highlight the flexibility of EDTA in accepting a large range of metal cations in its binding site.

Infrared Spectroscopic Study of Binding Interaction of Metal Complexes with Mefenamic Acid (MFA)

Aims: The foremost aim of this study was to evaluate the 1:1 formed complex when mefenamic acid interacts with Cu2+, Zn2+, and EDTA4- metal at the physiological condition, which provides a better understanding of the pharmacological studies. This research provided information on the binding affinity of mefenamic acid with selective metals. It helps with preparative, structural, and reactivity studies for multiple drug designs in pharmaceutical fields.
 Place and Duration of Study: Department of Pharmacy, Stamford University Bangladesh, Dhaka, Bangladesh & CARS ((Centre for Advanced Research in Sciences), University of Dhaka. The duration of this study is between September to December 2022.
 Study Design: The Infrared spectra of Copper (Cu), Zinc (Zn), and Ethylenediaminetetraacetic Acid (EDTA) complex of Mefenamic Acid were investigated in the region between 4000 and 400 cm-1. These spectra were compared to standard peaks with specific functional groups. The binding interactions of the selected metal ions were demonstrated by significant variations in the intensities of the amino group of mefenamic acid after metal complexation.
 Results: The interactions of the metal ions with the acid product have resulted in the alteration of the functional structure, characterized by a negligible reduction in the structure of mefenamic acid. The change in position of the characteristic bands, or the increase/ decrease in the number of bands and appearance of a new metal-atom bond, helps to confirm the formation of a complex.
 Conclusion: It has been recently found that metal-based complexes decrease antiviral, antibacterial, and anticancer action. In order to construct actively functioning medications, it is vital to study the ability of physiologically active metal ions to interact with metalloproteinases like albumin, which transport and distribute these metal ions. The current research set a standard for repeatable mefenamic acid metal ion research.

Radioactive isotope separation with 3D-printed flow-based device.

Radioactive isotope (RI) metals are a new type of tracer for positron emission tomography generated from the target metal by proton irradiation using a cyclotron. The generated metal RIs need to be separated from the target metal rapidly and effectively. In the present study, we developed a 3D-printed flow device to separate metal RIs from target metals. The separation was performed with selective formation of ethylenediaminetetraacetic acid (EDTA) complex based on the difference in formation constants. The RI metal selectively formed a EDTA complex, thus changing its ionic charge in solution. The solution was then introduced into a cation exchange column for selective adsorption of the target metal. The solution with added chelator and controlled pH was introduced into the developed system and automatically separated metal RI from target metals within 14min. The separation method was applied to separate RI 67Ga from target metal Zn using a mixture of 107pg L-1 67Ga in 250mg L-1 Zn2+. The recoveries of 67Ga and Zn were 97% and 100%, respectively. Furthermore, an ultraviolet (UV) radiation reactor was integrated into the system to decompose the EDTA complex and recover the Ga3+ ion. Ga3+ recovery by UV radiation was effective, 87%. The developed system was also successfully applied to the separation of Zr and Y. Therefore, the method and system can be applied to separate other metal RIs from target metals.

Kinetic Modeling of the Anodic Degradation of Ni-EDTA Complexes: Insights into the Reaction Mechanism and Products

In this study, an electrochemical advanced oxidation process (EAOP) was employed to effectively degrade complexes of nickel and ethylenediaminetetraacetic acid (EDTA) present in electroless nickel plating wastewaters. Our results show that Ni-EDTA complexes can be effectively degraded by an EAOP with degradation of the complexes occurring at/near the anode surface via interaction with hydroxyl radicals generated on water splitting. Our results further show that the rate of Ni-EDTA degradation is not a function of the rate of any particular chemical reaction but, rather, is controlled by the rate of transport of Ni-EDTA to the anode surface. The oxidation of EDTA to smaller noncomplexing entities releases Ni2+, which is subsequently deposited onto the cathode as Ni0. While complete Ni-EDTA removal and Ni recovery are achieved within 2 h, the overall TOC removal by EAOP is limited, with only 50% TOC removal achieved after 2 h of treatment. The low affinity of small molecular weight EDTA degradation products (such as formic acid, glycine, oxamic acid, and acetic acid) for the anode surface limits oxidation of these compounds and overall TOC removal by the anodic oxidation process. We have developed a mathematical kinetic model that satisfactorily describes Ni-EDTA removal, Ni recovery, and TOC removal over a range of Ni and EDTA concentrations and provides a good description of the oxidation of various EDTA degradation intermediates. The mathematical model developed here, when coupled with the hydrodynamics of the electrochemical cell using a computational fluid dynamics tool, can assist in both cell design and the selection of operating parameters such that the performance of the EAOP process for Ni-EDTA degradation and TOC removal is optimized.

Development of two highly sensitive and selective sensor-assisted fluorescence immunoassays for trace determination of copper residues in food samples.

This study describes the development of two highly sensitive and selective sensor-assisted fluorescence immunoassays for the trace determination of copper ions, Cu(ii) residues, in food samples. These assays were the microwell-based fluoroimmuoassay (FIA) and the kinetic exclusion assay (KinExA). FIA and KinExA were assisted by a microplate reader and a KinExA™ 3200 immunosensor, respectively. Both FIA and KinExA were developed utilizing the same antibody, capturing reagent, and fluorescence signal-generating reagent. The antibody was a mouse monoclonal antibody, designated as 8D66, that specifically recognized the Cu(ii)-ethylenediaminetetraacetic acid complex (Cu(ii)-EDTA) but did not recognize Cu(ii)-free EDTA. The capturing reagent was Cu(ii)-EDTA covalently linked to bovine serum albumin protein (Cu(ii)-EDTA-BSA). The fluorescence-generating reagent was an anti-mouse IgG conjugated with fluorescein isothiocyanate (IgG-FITC). Both FIA and KinExA involved competitive binding reactions between Cu(ii)-EDTA complexes, formed in the sample solution, and Cu(ii)-EDTA-BSA conjugate which has been immobilized onto microwell fluorescence assay plates (in FIA) or polymethylmethacrylate beads (in KinExA) for a limited quantity of binding sites of 8D66 antibody. The conditions of both FIA and KinExA were investigated, and the optimum procedures were established. Both FIA and KinExA were validated, and all validation parameters were acceptable. Many different metal ions that are commonly encountered in food samples did not interfere with Cu(ii) analysis by both FIA and KinExA. Both assays were applied to the determination of Cu(ii) in food samples with satisfactory accuracy and precision. Both assays were compared favorably with inductively coupled plasma atomic emission spectroscopy. Comparative evaluation of FIA and KinExA revealed that KinExA had higher sensitivity and better precision than FIA, whereas, both assays had comparable accuracy. Both FIA and KinExA were superior to the existing atomic spectrometric methods for Cu(ii). The proposed FIA and KinExA are anticipated to effectively contribute to assessing Cu(ii) concentrations and controlling the exposure of humans to its potential toxicities.

Selective Extraction of Silver and Palladium in Leachate Based on EDTA Complexation: Electrodeposition, Nucleation Mechanism, and Kinetic Analysis

The development of green recycling technology for precious metals such as Ag and Pd from secondary resources can prevent environmental pollution caused by improper disposal, and it can alleviate resource shortage and promote sustainable development. Ag and Pd often coexist in some solid waste. This study proposed the extraction of Ag and Pd stepwise from leachate through the green technology of potential-controlled electrodeposition, and the reduction potential difference of Ag and Pd in solution was increased based on EDTA (ethylenediaminetetraacetic acid) complexation. The electrochemical behavior of Ag+ and Pd2+ in solution was investigated. It was determined that the electrodeposition separation of Ag+ and Pd2+ can be achieved with a pH of 9 and an EDTA molar ratio of 1:1.5 in the solution. With sequential electrodeposition at 0 V and −0.7 V, 99.3% of Ag and 96.15% of Pd were recovered, respectively, and their purity was achieved 100%. Pd electrodeposition conformed to three-dimensional instantaneous nucleation and growth mechanism analyzed with the Scharifker–Hills model. Compared with the EDTA-free environment, the diffusion coefficient of ions reduced, and the activation energy of Ag and Pd reduction reaction increased in the EDTA environment. This study provides an environmentally friendly and efficient method for precious metal recovery from secondary resources.

Ion Binding Site Structure and the Role of Water in Alkaline Earth EDTA Complexes.

The interactions between molecular hosts and ionic guests and their dependence on the chemical environment are challenging to disentangle from solution data alone. The vibrational spectra of cold complexes of ethylenediaminetetraacetic acid (EDTA) chelating alkaline earth dications in vacuo encode structural characteristics of these complexes and their dependence on the size of the bound ion. The correlation between metal binding geometry and the relative intensities of vibrational bands of the carboxylate groups forming the binding pocket allows us to characterize water-induced changes in molecular geometry. The evolution of these structural markers from bare ions to water adducts to aqueous solution illustrates the role of water for the structure of ion binding sites in chelators. The binding pocket of EDTA opens up in aqueous solution, bringing the bound ion closer to the mouth of the binding site and leading to an increased exposure of the ion to the chemical environment.

Study of Radium Behavior in Contact With Calcium-Silicate-Hydrates

Abstract Radium-226 is an important radionuclide with respect to the long-term safety of repositories for low and intermediate-level radioactive wastes, as well as deep geological repositories for high-level radioactive waste and spent nuclear fuel. To evaluate its mobility in the engineered barrier system of a repository, the sorption of radium on calcium-silicate-hydrates (CSH), which form the major hydration phases in cementitious materials, was studied. Radium sorption to CSH was found to be very fast, leading to steady-state between solid and liquid phase after less than four days. The dependency of the equilibrium distribution ratios on radium concentration, the calcium to silicon ratio in CSH, liquid to solid ratio, and temperature was investigated, and estimates of apparent activation energy, reaction enthalpy, entropy, and Gibbs energy of the sorption process were derived. Radium sorption on CSH can be described by linear isotherms with Rd values mostly in the order of 104 L/kg. Radium sorption was found to be an exothermic and spontaneous reaction probably governed by chemical reaction rather than diffusion. As expected, the presence of ethylene diamine tetraacetic acid (EDTA) at low concentrations led only to a small decrease in radium sorption, due to the strong competition of dissolved calcium for EDTA complexation. A comparison of the sorption behavior of various alkaline earth elements used as chemical analogs for radium confirmed the significant difference in the Rd values with sorption on CSH decreasing in the order Ra > Ba > Sr.

Enhancement of antibacterial activity by a copper(II) and zinc(II) in chelation with ethylenediaminetetra-acetic acid and urea complex

Enhancement of antibacterial activity by a copper(II) and zinc(II) in chelation with ethylenediaminetetra-acetic acid and urea complex

From the Free Ligand to the Transition Metal Complex: FeEDTA- Formation Seen at Ligand K-Edges.

Chelating agents are an integral part of transition metal complex chemistry with broad biological and industrial relevance. The hexadentate chelating agent ethylenediaminetetraacetic acid (EDTA) has the capability to bind to metal ions at its two nitrogen and four of its carboxylate oxygen sites. We use resonant inelastic X-ray scattering at the 1s absorption edge of the aforementioned elements in EDTA and the iron(III)-EDTA complex to investigate the impact of the metal–ligand bond formation on the electronic structure of EDTA. Frontier orbital distortions, occupation changes, and energy shifts through metal–ligand bond formation are probed through distinct spectroscopic signatures.