EDTA In Aqueous Solution Research Articles

Multiclass, multiresidue method for the detection of antibiotic residues in distillers grains by liquid chromatography and ion trap tandem mass spectrometry

The increased production of ethanol in the US has resulted in large amounts of distillers grains (DG) which is an excellent feed supplement for livestock. However, the use of antimicrobials during ethanol fermentation has led to a growing concern over the possibility of their residues remaining in DG. To enable the detection of antimicrobial residues, a robust LC-MS/MS method was developed that included 13 antibiotics of diverse chemistries, ampicillin, penicillin G, tetracycline, oxytetracycline, chlortetracycline, bacitracin A, virginiamycin M1, chloramphenicol, erythromycin A, clarithromycin, tylosin A, monensin A and streptomycin. The residues were extracted with an aqueous solution of EDTA and trichloroacetic acid followed by methanol. The combined extract was subjected to a two-track cleanup and concentration on either hydrophilic polymeric or weak cation exchange solid phase extraction cartridges. The extracts are analyzed by LC/ion trap tandem mass spectrometry. The method was validated in dry DG matrix. Absolute recoveries of the analytes ranged from 50 to 100%. Accuracy ranged from 89 to 111% based on calibration by processed standards. The limits of detection and relative standard deviation are satisfactory to support future surveillance studies. The method was subsequently tested in three different end-products of DG: distillers dry grains, distillers wet grains and distillers grains solubles.

Recovery of radioactive cobalt from aqueous EDTA solutions using concentrated ozone

Oxidative decomposition of EDTA in aqueous solution under the action of ozone was studied. Conditions providing complete decomposition of EDTA and precipitation of radioactive cobalt in the form of hydroxide were found.

Comparative evaluation of magnetite dissolution efficiencies of EDTA and OEDP aqueous solutions

The influence of EDTA and OEDP on the magnetite dissolution rate in various experimental conditions was studied. From a comparative analysis of rate data in commensurate conditions, EDTA is a more efficient complexone than OEDP. The effect of both the nitrogen-bearing and the phosphorus-bearing complexones was to change the potential at the oxide/solution interface. The potential-controlling reaction was recognized as FeIIIY− + H+ + e = FeIIHY−.

The Effect of EDTA on the Deposition of ZnS Thin Film

Abstract Cyclic voltammetry studies in the presence of EDTA in aqueous solution were found to offer some noteworthy improvements in the electrodeposition synthesis of ZnS compound. EDTA has shown its capacity for improving the longevity of the deposition bath as well as adhesion of the deposited material on the substrate. The deposition condition of ZnS compound in the presence of EDTA was found to be favorable in low acidic medium. The process could be carried out at room temperature without the need to increase solution temperature.

Oxidative degradation of EDTA in aqueous solutions under UV irradiation

The efficiency of high-intensity pulsed UV irradiation for degradation of organic compounds in decontamination solutions was examined. The conditions ensuring virtually complete degradation of EDTA in alkaline and acidic solutions simulating decontamination solutions T and T-Ts were determined. The optimal ratios of H2O2 and EDTA providing complete photochemical oxidation of the complexone were evaluated.

Effect of Complexation on Photocatalytic Degradation of Dissolved Organic Nitrogen Compounds

The effect of metal ions on TiO2 mediated photocatalytic oxidation for the determination of dissolved organic nitrogen compounds is investigated. Ethylenediaminetetraaceticacid was chosen as a model molecule for DON compounds. At pH 2, 5, 7, and 10 aqueous EDTA solutions were irradiated at 254 nm in the presence of Fe2+, Cu2+, Zn2+, Ni2+ or Co2+ ions. The sum of produced nitrate, nitrite, and ammonium ion concentrations gave the total oxidation recovery. At low pH, the photocatalytic oxidation recoveries of Fe‐EDTA, Ni‐EDTA, and Co‐EDTA were significantly lower than the photocatalytic degradation of EDTA. The presence of free Fe2+, Ni2+, and Co2+ ions decreased the photocatalytic oxidation recovery. The [NH4 +]/[NO3 −] ratio was higher for Cu‐EDTA.

Chitosan modified with Reactive Blue 2 dye on adsorption equilibrium of Cu(II) and Ni(II) ions

This study aimed at immobilizing Reactive Blue 2 (RB 2) dye in chitosan microspheres through nucleophilic substitution reaction. The adsorbent chemical modification was confirmed by Raman spectroscopy and thermogravimetric analysis. This adsorption study was carried out with Cu(II) and Ni(II) ions and indicated a pH dependence, while the maximum adsorption occurred around pH 7.0 and 8.5, respectively. The pseudo second-order kinetic model resulted in the best fit with experimental data obtained from Cu(II) ( R = 0.997) and Ni(II) ( R = 0.995), also providing a rate constant, k 2, of 4.85 × 10 −4 and 3.81 × 10 −4 g (mg min) −1, respectively, thus suggesting that adsorption rate of metal ions by chitosan-RB 2 depends on the concentration of ions on adsorbent surface, as well as on their concentration at equilibrium. The Langmuir and Freundlich isotherm models were employed in the analysis of the experimental data for the adsorption, in the form of linearized equations. Langmuir model resulted in the best fit for both metals and maximum adsorption was 57.0 mg g −1 (0.90 mmol g −1) for Cu(II) and 11.2 mg g −1 (0.19 mmol g −1) for Ni(II). The Cu(II) and Ni(II) ions were desorbed from chitosan-RB 2 with aqueous solutions of EDTA and H 2SO 4, respectively.

Mechanism of reaction of alkyl radicals with (NiIIL)2+ complexes in aqueous solutions

The reactions of methyl radicals, *CH3, with the macrocyclic complexes Ni(II)L(1-5) (L(1-5) = cyclam derivatives, vide infra) and Ni(II)edta in aqueous solutions were studied. Methyl radicals react with all these nickel complexes, forming intermediates with Ni(III)-C sigma-bonds. The L(m)Ni(III)-CH3 complexes are formed in equilibria processes with relatively fast forward rate constants of k(f) > 1 x 10(8) M(-1) s(-1) (except in the case of NiL2-trans I cyclam, where the reaction is slower). In all cases the decomposition of the transient complexes occurs via the homolytic cleavage of the metal-carbon sigma-bond. When the homolysis is relatively slow, an isomerisation process of the transient is also observed with the exception of NiL2, where no isomerisation was observed. The results suggest that the strength of the Ni(III)-CH3sigma-bond is mainly affected by steric hindrance.

Patterning micron-sized features in a cross-linked poly(acrylic acid) film by a wet etching process.

This paper describes a photolithographic method to create sub-micron-scale patterns of cation-cross-linked poly(acrylic acid) (CCL-PAA). PAA can be cross-linked with a wide range of metal cations-including, but not limited to, Ag, Ca, Pd, Al, La, and Ti. Upon patterning a positive photoresist (diazonaphthoquinone-novolac resin) on a film of CCL-PAA, the exposed regions of CCL-PAA were etched by either an aqueous NaOH or EDTA solution. The initial cross-linking cation could be exchanged for a second cation that could not be patterned photolithographically. We used these patterned films of CCL-PAA i) to host and template the reduction of metallic cations to metallic nanoparticles, and ii) to fabricate porous, low- dielectric substrates.

Adsorption of chromium from aqueous solution using chitosan beads

A basic investigation on the removal of Cr(III) and Cr(VI) ions from aqueous solution by chitosan beads was conducted in a batch adsorption system. The chitosan beads were prepared by casting an acidic chitosan solution into an alkaline solution. The influence of different experimental parameters; pH, agitation period and different concentration of Cr(III) and Cr(VI) ions was evaluated. A pH 5.0 was found to be an optimum pH for Cr(III) adsorption, and meanwhile pH 3.0 was the optimum pH for the adsorption of Cr(VI) onto chitosan beads. The Langmuir and Freundlich adsorption isotherm models were applied to describe the isotherms and isotherm constants for the adsorption of Cr(III) and Cr(VI) onto chitosan beads. Results indicated that Cr(III) and Cr(VI) uptake could be described by the Langmuir adsorption model. The maximum adsorption capacities of Cr(III) and Cr(VI) ions onto chitosan beads were 30.03 and 76.92 mg g−1, respectively. Results showed that chitosan beads are favourable adsorbents. The Cr(III) and Cr(VI) ions can be removed from the chitosan beads by treatment with an aqueous EDTA solution.

Comparative studies on the adsorption of Cr(VI) ions on to various sorbents

The adsorption of Cr(VI) ions onto various sorbents (chitin, chitosan, ion exchangers; Purolite CT-275 (Purolite I), Purolite MN-500 (Purolite II) and Amberlite XAD-7) was investigated. Batch adsorption experiments were carried out as a function of pH, agitation period and concentration of Cr(VI) ions. The optimum pH for Cr(VI) adsorption was found as 3.0 for chitin and chitosan. The Cr(VI) uptake by ion exchangers was not very sensitive to changes in the pH of the adsorption medium. The maximum chromium sorption occurred at approximately 50 min for chitin, 40 min for Purolite II and 30 min for chitosan, Purolite I and Amberlite XAD-7. The suitability of the Freundlich and Langmuir adsorption models were also investigated for each chromium-sorbent system. Adsorption isothermal data could be accurately interpreted by the Langmuir equation for chitosan, chitin, Purolite I and Purolite II and by the Freundlich equation for chitosan, chitin and Amberlite XAD-7. The chromium(VI) ions could be removed from the sorbents rapidly by treatment with an aqueous EDTA solution and at the same time the sorbent regenerated and also could be used again to adsorb by heavy metal ions. The results showed that, chitosan, which is a readily available, economic sorbent, was found suitable for removing chromium from aqueous solution.

Effect of sulfur compounds on biological reduction of nitric oxide in aqueous Fe(II)EDTA2− solutions

Biological reduction of nitric oxide (NO) in aqueous solutions of EDTA chelated Fe(II) is one of the main steps in the BioDeNOx process, a novel bioprocess for the removal of nitrogen oxides (NOx) from polluted gas streams. Since NOx contaminated gases usually also contain sulfurous pollutants, the possible interferences of these sulfur compounds with the BioDeNOx process need to be identified. Therefore, the effect of the sulfur compounds Na2SO4, Na2SO3, and H2S on the biological NO reduction in aqueous solutions of Fe(II)EDTA2- (25 mM, pH 7.2, 55 degrees C) was studied in batch experiments. Sulfate and sulfite were found to not affect the reduction rate of Fe(II)EDTA2- complexed NO under the conditions tested. Sulfide, either dosed externally or formed during the batch incubation out of endogenous sulfur sources or the supplied sulfate or sulfite, influences the production and consumption of the intermediate nitrous oxide (N2O) during Fe(II)EDTA2- bound NO reduction. At low concentrations (0.2 g VSS/l) of denitrifying sludge, 0.2 mM free sulfide completely inhibited the nitrosyl-complex reduction. At higher biomass concentrations (1.3-2.3 g VSS/l), sulfide (from 15 microM to 0.8 mM) induced an incomplete NO denitrification with N2O accumulation. The reduction rates of NO to N2O were enhanced by anaerobic sludge, presumably because it kept FeEDTA in the reduced state.

Physicochemical modification of EDTA solutions to improve the smear layer removal in dental applications

In endodontic treatment, the canal instrumentation produces debris (smear layer) that blocks the root canal and dentinal tubules reducing the adhesion with the obturation material, favouring microfiltration and bacteria growth. EDTA aqueous solution is the most used and effective de-mineralizing agent because produces a strong chelating effect on the calcium ions of the hydroxyapatite. However, its physicochemical properties (viscosity, surface tension, capillarity penetration and diffusion time) should be modified to improve its cleaning effects; this can be done by adding controlled amounts of ethanol. The diffusion time can be increased up to 244%, which renders in an increment in the residence time of the de-mineralizing agent on the root canal and tubules, providing the required time to allow the chemical reaction with the smear layer takes place. Additionally, ethanol reduces penetration (45%) making the cleaning effective near the root canal, where it is required. SEM micrographs show the tubules before and after this treatment at different ethanol concentrations.

Experimental and Modeling Studies on the Absorption of NO in Aqueous Ferrous EDTA Solutions

This work describes an experimental and modeling study on an industrial relevant process (i.e., the absorption of NO in aqueous FeII(EDTA) solutions) to accurately determine the equilibrium constant of the reaction in the temperature range of 299−329 K. The experiments were carried out in a stirred cell contactor using a pH of 7 and an initial FeII(EDTA) concentration of 7−9 mol/m3. A dynamic reactor model was developed to describe the experimental absorption profiles. Mass transfer effects were taken into account using the penetration theory for mass transfer. Excellent fits were obtained between measured and modeled profiles when assuming that the reaction takes place in the instantaneous regime. The following temperature dependence for the K value was obtained: K = exp((4702/T) − 8.534). Dynamic reactor modeling not only allowed calculation of the equilibrium constants of the reaction but also provided accurate values for the ratio of the diffusivity of FeII(EDTA) and NO (rP) at various temperatures. This ratio is of extreme importance for the design of a reactive NO absorption unit and could be expressed as: rP = −1.775 × 10-4T2 + 0.11T − 16.93.

Decomposition of Ethylenediaminetetraacetic Acid Using He‐Ar‐O2 Dielectric Barrier Discharge

AbstractSummary: DBD generated by mid‐frequency AC (30 kHz) at atmospheric pressure was used for the degradation of EDTA in aqueous solution. The concentration of EDTA was measured by HPLC and TOC analysis. More than 90% of EDTA (initial concentration of 0.2 wt.‐%) was decomposed by DBD degradation, and the TOC content was reduced to below 60% of the initial value within one hour. The reaction was faster at high plasma generation voltages. At an applied voltage of 14 kV, 50% of EDTA was degraded by DBD degradation in only 10 min. magnified image

Synthesis and characterization of chelating resins with amino moieties and application on removal of copper(II) from EDTA complexes

Strong-field ligands (amino moieties) are introduced into a hydrogel resin to obtain a chelating resin via inversion suspension polymerization. The characteristics of chelating copolymers are measured by using Fourier transform IR spectroscopy (FTIR), elemental analysis (EA), and scanning electron microscopy (SEM). After chelating copolymers adsorb cupric ions, the absorption peak of stretch NH is shifted to higher frequency because of a coordination reaction from the FTIR spectra. Furthermore, the mechanism of metal complex adsorption on the chelating copolymer is that the strong-field chelating ligand decomposes the bonding of the metal complexes and recoordinates the cupric ion to a chelating polymer, which is examined via FTIR, SEM with EA, and ionic chromatography analysis. The maximum adsorption capacity of cupric ions is 1.08 mmol/g and the adsorption capacity increases with the increase of the pH of the solution. The stability constant of the Cu chelating copolymer is 1018.72, and it can have competition adsorption with EDTA in aqueous solution. These amino chelating copolymers can be used not only to recover metal ions but also to move anion pollution in wastewater. It is interesting that parts of the cupric ions adsorbed on the chelating copolymer are reduced into cupreous ions and/or copper atoms after electron spectroscopy for chemical analysis measurement. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2457–2468, 2005

Equilibrium and kinetics studies of adsorption of copper (II) on chitosan and chitosan/PVA beads

The adsorption of Cu(II) ions from aqueous solution by chitosan and chitosan/PVA beads was studied in a batch adsorption system. Chitosan solution was blended with poly(vinyl alcohol) (PVA) in order to obtain sorbents that are insoluble in aqueous acidic and basic solution. The adsorption capacities and rates of Cu(II) ions onto chitosan and chitosan/PVA beads were evaluated. The Langmuir, Freundlich and BET adsorption models were applied to describe the isotherms and isotherm constants. Adsorption isothermal data could be well interpreted by the Langmuir model. The kinetic experimental data properly correlated with the second-order kinetic model, which indicates that the chemical sorption is the rate-limiting step. The Cu(II) ions can be removed from the chitosan and chitosan/PVA beads rapidly by treatment with an aqueous EDTA solution. Results also showed that chitosan and chitosan/PVA beads are favourable adsorbers.

Effect of different extracting solutions on the electrodialytic remediation of CCA-treated wood waste Part I.: Behaviour of Cu and Cr

Removal of Cu and Cr from chromated copper arsenate (CCA)-treated wood waste under batch electrodialytic conditions was studied. The effect of different types of extracting solutions, such as deionised water or aqueous solutions of NaCl, formic acid, oxalic acid, and EDTA, on the magnitude and direction of the fluxes of Cu- and Cr-containing species in the electrodialytic cell was investigated. Oxalic acid was found to have the best performance if simultaneous removal of the two elements is required (removal efficiencies of 80.5% for Cu and 87.4% for Cr, respectively). A mixture of oxalic acid and formic acid also led to similar removal efficiencies. In these experiments, the target elements were accumulated in both the anode and cathode compartments of the electrodialytic cell due to the formation of negatively charged complexes with the organic acids used besides the free cationic forms. The latter were not present if EDTA was the extracting solution resulting in directing the Cu and Cr fluxes to the anode compartment. Contrary, these fluxes were exclusively to the cathode compartment if deionised water or an aqueous solution of NaCl were used. These extracting solutions proved suitable for solubilising (re-mobilisation) of Cu but were less efficient for Cr removal (less than 20% removal). Overall, the results obtained show the important role of the proper selection of the type and composition of the extracting solution for the success of subsequent electrodialytic removal of Cu and Cr from CCA-treated wood waste.

Size-controllable sonochemical synthesis of thermoelectric material of Bi2Se3 nanocrystals

We report the sonochemical synthesis of thermoelectric materials of Bi2Se3 nanocrystals in the 6.9–15.2 nm size regime. In this method, the size of Bi2Se3 nanocrystals can be easily controlled by varying the concentration of EDTA in aqueous solution.

Reactivity of OH[rad] and e−aq from electron beam irradiation of aqueous solutions of EDTA and aminopolycarboxylic acids

Electron beam irradiation of aqueous solutions of EDTA, EDDA NN′, NTA, IDA and Cu-EDTA was performed in the presence of scavengers for the hydroxyl radicals (methanol) or for the solvated electrons (hydrogen peroxide). Experiments showed that for each molecule, the G-value decreases as the radiation dose increases from 1 to 25kGy, and for EDTA, when the initial concentration decreases from 10 to 0.1mmoll−1. At pH 8 and for 5kGy, the G-values of NTA, IDA, EDTA and EDDA NN′ removal ascribed to OH radicals are, respectively, 0.06, 0.06, 0.15 and 0.20μmolJ−1, whereas for the solvated electrons the G-values were, respectively, 0.01, 0.01, 0.06 and 0.04μmolJ−1.The rate constants of hydroxyl radicals and solvated electrons were determined by comparison with one competitor. For each active species (hydroxyl radical or solvated electron), the reactivity is connected to the number of nitrogen atoms and acetate groups. The rate constants of OH radicals are above 1010 and 8.6×109lmol−1s−1 for EDDA NN′ and EDTA, respectively, 2.1×109lmol−1s−1 for IDA and 6.1×108lmol−1s−1 for NTA. The reactivity of solvated electrons is smaller and the rate constants are in the range 1.9×106–3.7×106lmol−1s−1 for NTA, IDA and EDDA NN′ and equal 1.4×107lmol−1s−1 for EDTA. The reactivity of the complex Cu-EDTA towards OH does not differ to a large extent from EDTA whereas with e−aq the reactivity of Cu-EDTA is better than EDTA since ke−/Cu-EDTA reaches 2.2×109lmol−1s−1.It follows that when both active entities (OH and e−aq) are involved in the electron beam irradiation process, the removal of free aminopolycarboxylic acids is mainly due to OH radicals. However, the complex Cu-EDTA is concerned by both e−aq and OH radicals.