EDTA In Aqueous Solution Research Articles

Comparative SEM and TEM examination of the ultrastructure of the resin-dentin interdiffusion zone.

The resin-dentin interdiffusion zone produced by a dentin-adhesive system that removes the smear layer and concurrently decalcifies superficial dentin was morphologically examined by both scanning and transmission electron microscopy. Cross-sectioned resin-bonded dentin discs were etched with an argon-ion beam to make the resin-dentin interface observable by SEM. For the TEM examination, the sections were partly decalcified by an aqueous EDTA solution to facilitate ultramicrotomy and to disclose the ultrastructure of the interdiffusion zone. Both SEM and TEM confirmed the presence of the resin-dentin interdiffusion zone as the junction between the deep unaltered dentin structure and the restorative resin. Within the interdiffusion zone, three sublayers with characteristic ultrastructure and staining were identified by TEM. An upper diffuse black layer contained few structural features. Underneath, partially-altered collagen fibrils were closely packed, mostly running parallel with the interface and perpendicular to the dentinal tubules. Their outline was electron-dense, forming tunnel-like structures. At the base of the upper layer, several stained projections were found to bulge out into the underlying collagen network and appeared to be confined by obstructive, parallel-running collagen fibrils. Finally, the third dense layer, containing hydroxyapatite crystals, demarcated the superficially demineralized dentin layer from the deeper unaltered dentin. Resin diffusion into the decalcified dentin surface layer was evident, but diminished with depth, presumably reducing deeper resin impregnation into the interfibrillar spaces. The citric acid dentin-pretreatment probably caused denaturation of the superficial collagen fibrils. Its decalcifying effect gradually weakened with depth, leaving behind hydroxyapatite crystals at the base of the interdiffusion zone.(ABSTRACT TRUNCATED AT 250 WORDS)

Photoelectrochemical cells consisting of phenosafranin-EDTA and different redox couples with illuminated semiconductor electrode

A photoelectrochemical cell, semiconductor (In 2O 3)/dye-EDTA//redox couple/Pt, has been developed using phenosafranin dye and EDTA aqueous solution in one compartment and Cu +/Cu 2+, Fe(CN) 6 4−/Fe(CN) 6 3−, I −/I 2, and Fe 2+/Fe 3+ in the other compartment of an H-shaped cell separated by a glass membrane. All the cell characteristics such as open-circuit voltage, short-circuit current, fill factor, power efficiency, and solar energy efficiency have been determined. There is 2-3-fold increase of efficiency of the cell compared to the same cell with illuminated Pt electrode.

Photodissolution of iron oxides. IV. A comparative study on the photodissolution of hematite, magnetite, and maghemite in EDTA media

The thermal and 254-nm photochemical dissolution reactions of magnetite (Fe3O4), maghemite (γ-Fe2O3), and hematite (α-Fe2O3) suspended in EDTA aqueous solutions were compared. γ-Fe2O3 and Fe3O4 are thermally and photochemically more reactive than α-Fe2O3. Both thermal and photochemical dissolution reactions are governed by an initiation step, which involves the production of FeIIaq, and a subsequent thermal reaction of these ions with the solid, to produce FeIIIaq. The initiation step under UV irradiation involves the photoreduction of surface >FeIII – EDTA complexes to yield FeIIaq and the photooxidation of adsorbed EDTA to yield CH2O and other oxidation products. After FeIII – EDTA complexes build up in solution through the following step, homogeneous photolysis is the main source of FeII and CH2O. Oxides with spinel type structure are characterized by faster rates in the two processes, and O2 may inhibit the dissolution processes by changing the stoichiometry of the initiation step to that of the autooxidation of EDTA. The relative importance of autooxidation and photodissolution depends on the nature of the oxide and the experimental conditions. Photooxidation reaction rates parallel those of the photodissolution initiation steps, and long-term stability towards photocorrosion (dissolution) implies low photocatalytic activity for the oxidation of EDTA. The set of differential equations describing all the reaction rates is discussed and applied to the different cases.

Leaching kinetics of colemanite by aqueous EDTA solutions

The dissolution kinetics of colemanite, a boron-containing mineral, in aqueous disodium EDTA solutions were studied. The effects of concentration and pH of the solution, particle size, and temperature were examined. A decrease in pH and particle size increased the dissolution rate, while an increase in the concentration of the solution and temperature increased the rate. The activation energy and pre-exponential factor were calculated as 50.6 kJ mol-1 and 5.14 x 107 m s-1, respectively.

Characterization by radiotracer of flow dynamics in laboratory and pilot-plant molecular sieves columns dehydrating organic liquids

Experiments with113mIn radiotracer in 0.01M aqueous solutions of EDTA have been carried out to investigate the fluid flow dynamics in columns of three different diameters filled with molecular sieve spherical particles. The dependence of the Peclet number upon the column diameter-to-particle diameter ratio is demonstrated and irregularities and fluctuations for ratios smaller than 10 are observed. The influence of these phenomena on the adsorption process was investigated.

ヒメダカにおける｀１０９´Ｃｄの取り込みと排出に対する共存有機物質の影響（食物連鎖における有害物質の移行‐Ｘ）

Intake, excretion and distribution of cadmium in the HIMEDAKA Oryzias latipes were investigated using 109Cd. Fish were reared in Cd aqueous solution, in that coexisted with cysteine (CySH), in that coexisted with EDTA and in that coexisted CySH plus EDTA, respectively. The concentration of the chemicals was shown in Fig. 1. In the comparison of Cd distribution of the fish reared in sole existence of Cd, intake of Cd in the alimentary canal and depressed intake in the other viscera was observed under the coexitence of CySH. On the other hand, a remarkably depressed intake of Cd was observed under the coexistence of EDTA. The effect of CySH was cancelled in the simultaneous existence of EDTA. Fish were also reared in Cd aqueous solution, in Cd + CySH aqueous solution and in Cd + EDTA aqueous solution, respectively, for 72 hr. The concentration of the chemicals in this experiment was shown in Fig. 7. After the exposure, the fish had reared in Cd were transfered into distilled water, the fish had in Cd + CySH were into CySH aqueous solution and the fish in Cd + EDTA were into EDTA aqueous solution. The promoting excretion of Cd under the existence of these chemicals was observed. From the observation, a possible mechanism of effect of the coexisted chemicals was discussed.

Extraction of rare earth elements with organophosphorus extractants as carriers in supported liquid membranes

The membrane extraction of Y, Ce, Eu, Tm and their binary mixtures Ce−Y, Ce−Eu, Ce−Tm with supported liquid membranes containing TBP and HDEHP as carriers in decanedodecane hydrocarbon solvent, has been studied. Upon extraction with TBP aqueous nitrate solutions of rare earth elements (REE) were used as feed phase. In some cases they also contained EDTA or DCTA. In most cases, the receiving phase was an aqueous solution of EDTA. Extraction with HDEHP was performed from nitrate and chloride solutions and the receiving phase was the corresponding dilute acid. Pertraction of an element through a membrane was studied as a function of time and of initial composition of phases. The results are presented in the following forms: flux of metal through membrane, coefficients of permeability, separation factors and effective diffusion coefficients.

Studies on the long-term storage of mature, green tomato fruit

SummaryGreenhouse-grown mature-green tomato fruit (Lycopersicon esculentum cv. Caruso) were stored under air or modified atmospheres (MA-3% 02 plus 2% C02) at 6 and 12°C followed by ripening for seven days at 22°C. Treatments with aqueous solutions of calcium, EDTA, EGTA, BHT, a-tocopherol and paclobutrazol were applied as dips to assess their ability to prevent chilling injury (Cl) or retard senescence. Chemical treatments were not beneficial to the quality attributes of the fruit relative to the control, and MA storage did not alleviate Cl symptoms relative to the air stored samples. Greenhouse-grown fruit could be stored for at least 30 days in the mature-green state at 12°C under MA with no detectable changes in quality, but samples kept at 6°C showed marked deterioration after 15 days of storage under both air and MA. Samples stored at 12°C under an air atmosphere for 30 days ripened completely. Field-grown mature green tomato fruit (Lycopersicon esculentum cv. Heinz 91-29) stored at 12°C under MA co...

Precipitation Behavior of Lanthanoid(III) Complexes with 2,6-Diacetylpyridine Bis(benzoylhydrazone) in Methanol and Application to Mutual Separation of Neodymium and Holmium

The precipitation behavior of lanthanoid(III) ions (La-Ho except for Pm) has been studied in methanol by the use of 2, 6-diacetylpyridine bis(benzoylhydrazone) as a precipitant. The recoveries of Gd and Tb were very low compared with other lanthanoids. Rough separation of the lighter and heavier lanthanoid groups has also been examined using the (Nd+Ho)-mixed solution. For the initial solution with 0.1-9.0 of the Nd/Ho molar ratios, decontamination factors (DF) of Nd in the precipitate were estimated as 0.4-12.5, whereas those of Ho remained in the solution were estimated as 0.5-17.5. The precipitant was recovered almost completely as a metal-free form by adding the aqueous EDTA solution to the precipitate and the filtrate.

Rate constants for the scavenging of tris(bipyridine)ruthenium(3+) by EDTA in aqueous solution

Etude cinetique du transfert d'electron entre Ru(bipyridine) 3 2+ et le methylviologene provoque par irradiation lumineuse du complexe du ruthenium. Le processus fait intervenir la formation de radicaux, l'EDTA constitue un reactif sacrificiel permettant de rendre le transfert irreversible et par consequent d'accumuler le radical cationique du methylviologene dans la solution

Studies on storage photoelectrochemical cell consisting of phenazine dye-EDTA and different redox couples

A new type of photoelectrochemical cell has been developed using phenazine dye and EDTA aqueous solution and aqueous solution of different redox couples separated by a Pyrex sintered glass membrane (porosity G-4). The different phenazine dyes used are phenosafranin. safranin-O, safranin-T, and neutral red. The redox couples used are Cu + Cu 2+ , Fe(CN) 6 4− Fe(CN) 6 3− , I − I 2 , and solFe 2+ Fe 3+ . An interesting observation is that the growth of maximum photovoltage takes 15–25 min, whereas the decay to the original dark voltage requires two to three days. Cell characteristics such as open-circuit voltage, short-circuit current, fill factor, power efficiency, and solar energy efficiency have been determined.

抗生物質の化学的分析法の検討(第2報)プレパックC<SUB>18</SUB>カートリッジのテトラサイクリン系抗生物質への適用について

The common tetracyclines (TCs) in fish tissues which are used in agriculture, tetracycline, oxytetracycline, and chlortetracycline, are analysed using an ODS-cartridge extraction device, and high performance thin layer chromatography (HPTLC) followed by densitometry. Fish tissue is blended in 0.1 M disodium ethylenediaminetetraacetate (di-Na EDTA)-McIlvaine buffer (pH 4.0) and centrifuged. The supernatant is adsorbed on the pretreated ODS-cartridge with 0.2 M di-Na EDTA aqueous solution, the cartrige is washed with water, and TCs are eluted with ethanol. The concentrated residue is spotted on a silica gel HPTLC plate predeveloped with saturated di-Na EDTA aqueous solution. The plate is then developed with chloroform-methanol-5% di-Na EDTA aqueous solution (65 : 20 : 5, lower layer). The amounts of TCs present on the developed plate are determined by ultraviolet absorption densitometry. Recoveries of TCs from fish samples fortified at level of 1 ppm are 60.2-78.6%.

Dissolution of Cu 2S in aqueous edta solutions containing oxygen

The mechanism of the reactions taking place in the heterogeneous system: synthetic polydispersive Cu 2S-ethylediaminetetraacetic acid (EDTA)—O 2—H 2O has been investigated. The partial pressure of oxygen and pH of the solution were found to exert a significant effect on the process kinetics. The dissolution rate does not depend, in practice, on the agitation rate and the EDTA concentration exerts an influence only at higher partial oxygen pressures. Dissolution of Cu 2S in aqueous EDTA solutions proceeds in two steps with the formation of CuS as an intermediate. In acid and neutral solutions the final products of dissolution are elementary sulphur and Cu(EDTA) 2- complex ion. The activation energy ΔE = 10.4kJ/mol (2.4 kcal/mol) suggests a diffusion controlled process. In alkaline solutions sulphur is oxidized to the sulphate ion and the dissolution process is kinetically controlled, ΔE = 41.4 kJ/mol (9.9 kcal/mol).

Formation process of nitrosyl-ethylenediam-inetetraacetato-iron(II) complex from nitrogen dioxide in a weakly acidic solution

Formation of nitrosyl-ethylenediaminetetraacetatoiron (II) complex, Fe (I I)NO- EDTA, by absorption of nitrogen dioxide to the iron(II)-EDTA aqueous solution was studied by controlled potential electrolysis and spectrophotometry. The NO2 introduced into the iron(II)-EDTA aqueous solution was converted to HNO2 and HNO3 as eqns. (1), (2), and Fe(II)NO-EDTA was formed from the reaction of HNO2 and iron(II)EDTA but HNO3 did not react with iron(II)EDTA.2NO2+H2O→HNO2+HNO3……(1)NO2+Fe(II)EDTA+H+→Fe(III)EDTA+HNO2……(2)In the reaction (1) one mole of HNO2 was formed from two moles of NO2, in the reaction (2) on the other hand, from one mole of NO2. The experimental result of the conversion rate of NO2 to Fe(II)NO-EDTA was increased with increasing iron(II)EDTA concentration and at high iron(II)EDTA concentration, 0.2 mol dm-3, the conversion rate was increased up to about 1.0. The total determinations of NO and NO2 should be carried out in the absorbent with high iron(II)EDTA concentration.

Effects of demineralization in an ethanolic solution of triethylammonium EDTA on solubility of bone matrix components and on ultrastructural preservation.

A solution of triethylammonium EDTA in 80% ethanol was evaluated as a demineralizing reagent for bone in comparison with aqueous solutions of EDTA. Biochemical analysis and acrylamide gel electrophoresis of extracts of finely powdered bovine bone showed that most of the macromolecular components of the organic matrix extractable in aqueous EDTA were retained when the triethylammonium EDTA reagent was used. Ultrastructural examination of chick tibias decalcified with the reagents showed a better preservation of cellular morphology, especially the membranous components, and more uniformly distributed ground substance, though slightly less in quantity, when the aqueous reagent was used. Use of the two reagents appears to be complementary, the alkylammonium reagent being more appropriate for use in studies of the organic matrix of bone, including immunohistochemical studies of bone glycoproteins. The aqueous reagent is more appropriate for use in studies of cellular ultrastructure.

The iron(III)-catalyzed oxidation of EDTA in aqueous solution

At temperatures above 100 °C iron(III) oxidizes coordinated EDTA to ethylenediaminetriacetic acid in aqueous solution in the absence of molecular oxygen. The reaction proceeds with an activation energy of 28.6 kcal/mol, and its rate is directly proportional to the concentration of Fe(III) and inversely proportional to pH. At 125 °C, the halflife of Fe(III) in the presence of excess EDTA is about 3 h at pH 9.3, but increases to >70 h at pH 5.4. The reaction is stoichiometric and no other reaction products or by-products were detected by nmr, gc, and gc – mass spectroscopy. In the presence of oxygen iron catalyzes quantitative oxidation of ethylenediamine-N,N,N′,N′-tetraacetic acid (EDTA) to ethylenediaminetriacetic acid. The copper(II)–EDTA chelate undergoes a similar reaction but higher temperatures [Formula: see text] are required. Iron(III) also oxidizes nitrilotriacetic acid (NTA) to iminodiacetic acid (IDA) and glycine. The hydrolyzed species Fe(OH)EDTA is shown to be the reactive intermediate, and the well-known (Fe–EDTA)2O4− μ-oxo dimer is shown not to exist at elevated temperatures (above 100 °C). Probable mechanisms are proposed for these reactions and comparisons are made with earlier work.

Mechanistic Interpretations of the Dye-sensitized Formation of Hydrogen Peroxide in an Aqueous Solution

Abstract Kinetic studies of the photosensitized formation of hydrogen peroxide and hyperoxide ions in a mixed aqueous solution of eosine, oxygen, and EDTA have been attempted on the basis of a switch-over of the primary processes, i.e., the so-called DD, DR, and DO mechanisms. The rate constants for reactions of E+···E− and E+···O2− intermediates with oxygen and EDTA were obtained. The yield of hydrogen peroxide via the DO-initiated mechanism was enhanced as much as one order of magnitude (≈0.012) by the addition of 0.15 mol dm−3 of sodium borate or sodium carbonate. The maximum yield, 0.08, of hydrogen peroxide was obtained in an aerated aqueous solution of 1.0×10−4 mol dm−3 of eosine, 5.0×10−2 mol dm−3 of EDTA, and 8.8×10−2 mol dm−3 of sodium borate.

A nuclear magnetic resonance relaxation study of iron(III) EDTA in aqueous solution

The two species, Fe(OH 2)Y − and Fe(OH)Y 2− of the iron(III) EDTA system in aqueous solutions were studied through their paramagnetic effect on the relaxation rates of 1H, 2H and 17O. The exchange mechanism of the bound water protons in Fe(OH 2)Y − was found to involve the exchange of the whole water molecule with an exchange lifetime of (1.3 ± 0.4) × 10 −6 s at 20°C. The proton exchange rate in the basic form Fe(OH)Y 2− is much slower, with a residue time of (8 ± 3) × 10 −6 s, at 20°C. The effective distance of the dipolar interaction between the unpaired electrons and the bound water protons in Fe(OH 2)Y − and the hydroxylic proton in Fe(OH 2)Y 2− was shorter than that expected on the basis of crystallographic data, but it was almost the same for the two species. The relevance of these results to the NMR evaluation of binding of hydroxide ion to the metal in the enzyme carbonic anhydrase is discussed.

Pulse radiolysis study of Cu (EDTA) 2− in aqueous solution in the presence of alcohols

The radiolysis of aqueous solutions of Cu EDTA 2- in the presence of a number of alcohols was studied by the pulse-radiolysis technique. After the reduction of Cu EDTA 2− by e − aq a complex is formed between Cu (I) EDTA 3− and the radicals resulting from the H-abstraction of the alcohols by OH and H radicals (·ROH). The absorption spectra for a number of these complexes are reported. For the following reactions the rate constants were determined in the presence of n-butanol as a radical scavenger ( dm 3 mol −1 s −1): Cu EDTA 2- + e - aq as 6 X 10 9 ( pH = 7); Cu EDTA 2- + OH as 2 X 10 9 ( pH = 7.5); Cu (I) EDTA 3- + ·ROH as 4 X 10 9 < k<5 X 10 9 ( pH = 7.5); Cu EDTA 2- + ·ROH as 5 X 10 5< k<1 X 10 6 ( pH = 7.5) and ROH Cu EDTA 3- + NO − 2 as 4 X 10 5 ( pH = 7.5). The value of the molar extinction coefficient of ROH Cu EDTA 3− at 440 nm is 5 X 10 3 dm 3 mol −1 cm −1.

Homogeneous Photoredox System for Hydrogen Production by Solar Energy

Abstract In a redox system consisting of 5 × 10-5 mol dm-3 Ru(bpy)32+ complex, 4 × 10-3 mol dm-3 methylviologen and 5 × 10-3 mol dm-3 EDTA in aqueous solutions (pH = 3 to 8.5) without catalyst, hydrogen is formed under illumination with light λ &gt; 360 nm. The highest yield was established in the pH-range between 4 and 5. The degradation of the components by prolonged use was studied spectroscopically. For comparison hydrogen evolution was also studied replacing EDTA by TEA or SCN-, respectively, in the above mentioned system.