Nitrilotriacetic Acid Concentrations Research Articles

Fabrication of nanoflower-like Ni2Co-S/CNTA with morphology controlled for high-performance supercapacitor

Morphology and structure regulation is considered to be an effective strategy to improve the energy storage performance of supercapacitor electrode materials. In this work, a series of graded Ni2Co-S/CNTA nanoflowers composed of self-assembled nanosheets or nanorods have been synthesized by nitrilotriacetic acid (NTA)-assisted hydrothermal strategy. Morphological analysis shows that the micromorphology of the unit structures made up nanoflowers can be controlled by adjusting the concentration of NTA. Thanks to the synergistic effect of high void space, hierarchical assembly mode and integrated composite structure, Ni2Co-S/CNTA nanoflowers promote the full exposure of rich active sites, it enhances the stability of the structure, and impart excellent energy storage performance. As expected, the optimized Ni2Co-S/CNTA-2 electrode exhibits excellent capacitive performance, including high specific capacitance (1670.2 F g−1 at 1.0 A g−1) and good cycle stability (86.5% after 5000 cycles). The maximum energy density of Ni2Co-S/CNTA-2//AC ASC device is 61.3 Wh·kg−1 at a power density of 816.7 W·kg−1 and its retention rate is 88.3% after 5000 cycles.

Phytoextraction of lead (Pb) contaminated soil by switchgrass (Panicum virgatum L): Impact of BAP and NTA applications

The accumulation of Pb deposits in soil is a growing global concern. Soil remediation options include phytoextraction that involves the use of plants and associated soil microorganism. Switchgrass (Panicum virgatum L.), a second-generation bioenergy crop was used in this study due to its ability to produce high biomass and grow in metal polluted soils. Plants were grown in Pb-contaminated soil (5,802.5 mg kg−1) in an environmentally controlled greenhouse. Plants were treated with exogenous application of the plant growth regulator (PGR) benzylaminopurine (BAP) or complete foliar nutrient solution (Triple-12®) twice a week until harvested. Plants also received the soil fungicide propiconazole (Infuse™) that was followed by the soil chelate nitrilotriacetic acid (NTA). Two concentrations of NTA were compared (5 mM and 10 mM) and combined application of NTA (10 mM) + APG (alkyl polyglucoside). Soil fungicide (propiconazole) was used to arrest arbuscular mycorrhizal fungi (AMF) activities in the roots of switchgrass in order to enhance Pb-phytoextraction. Lead (Pb) was measured in dry plant materials using an ICP-OES. Phytoextraction by switchgrass was significantly improved by dual soil applications of 10 mM NTA, APG and foliar applications of BAP which resulted in the greatestaverage Pb concentration of 5,942 mg kg−1. The average dry mass of plants and the average value for total phytoextracted Pb (mg) per pot were significantly greatestfor plants treated with 10 mM NTA, APG and BAP. Also, plants treated with NTA and BAP showed average bioconcentration factor of 1.02. The results suggested that chemically enhanced phytoextraction significantly improved biomass production of switchgrass and at the same time increased phytoextracted Pb which is important for phytoremediation and bioenergy industry.

Evaluation of Chelating Agents Used in Phytoextraction by Switchgrass of Lead Contaminated Soil.

Soil lead (Pb) contamination is a recognized environmental and global health problem. Phytoextraction of Pb using switchgrass (Panicum virgatum L.), a second-generation biofuel crop, is typically enhanced by soil chelation. The effectiveness of four different chelating agents, phytic acid (inositol hexaphosphate), citric acid, NTA (nitrilotriacetic acid), and EDTA (ethylenediaminetetraacetic acid) was examined in pot culture. Plants treated with EDTA (1 mM) showed significantly higher shoot Pb concentrations compared to control plants and plants treated with other chelates. Lead-solubility following phytoextraction was examined by soil washing using 0.01 and 0.05 M acetic acid as an extractant solution revealed no significant differences in Pb concentrations in soil among different chelate treatments and control. Furthermore, the effects of different concentrations (1, 2, 5 and 10 mM) of NTA on Pb phytoextraction of switchgrass were examined. Plants receiving 5 mM and 10 mM NTA had significantly higher foliage concentrations of Pb compared to plants treated with lower levels (1 and 2 mM) of NTA. Moreover, the effect of NTA application alone was significantly improved by a combined application of Triton X-100, an alkyl polyglucoside (APG); the Pb concentration in the foliage of switchgrass was more than doubled when treated with NTA combined with APG. The use of NTA combined with APG has great potential in improving phytoextraction efficiencies of switchgrass on Pb-contaminated soils.

Morphology controlled hierarchical NiS/carbon hexahedrons derived from nitrilotriacetic acid-assembly strategy for high-performance hybrid supercapacitors

• A nitrilotriacetic acid-assisted strategy for controllable synthesis of NiS/carbon hexahedrons was proposed. • Synchronous realization of the combination of carbon with NiS and morphology controlled in one step. • Formation mechanism and determinants of NiS/carbon composites are revealed. • Enhanced power density (4187.2 W kg −1 ) and energy density (30.8 Wh kg −1 ). Effective adjustment of structure and morphology is considered to be an available strategy to improve the energy storage performance of supercapacitor electrode materials. Herein, a series of hierarchical NiS/carbon hexahedrons consist of self-assembling nanoplates or nanorods were synthesized via nitrilotriacetic acid (NTA)-assisted hydrothermal strategy. This study demonstrates that the micro-morphology of the unit structure constituting the hexahedrons can be controlled by adjusting the concentration of NTA. Benefiting from synergetic effect of high void space, hierarchical assembly mode and integrated composite structure, NiS/carbon hexahedrons promote adequate exposure of abundant active sites and enhance the structural stability, donating superior energy storage performance. As expected, the optimized NiS/carbon electrode (NiS/NTA-2) exhibits superb capacitive performance, including excellent specific capacitance of 1530.4 F g −1 at 1.0 A g −1 and remarkable cycle stability with 85.6% after 5000 cycles. Employing the as-prepared NiS/NTA-2 composites as positive electrode, the hybrid supercapacitor device with spectacular capacity of maximum energy density and power density up to 35.1 Wh kg −1 and 4509.3 W kg −1 and impressive long-term stability of 87.2% retention after 5000 cycles is assembled. Moreover, a light-emitting diode (LED) is successfully illuminated for up to 12 min by two devices connected in series. Based on this strategy, high-performance energy storage devices can be further developed through utilizing the modulation effect of metal complexes to design morphology controlled electrode materials.

Recycling of zinc oxide dust using ChCl-urea deep eutectic solvent with nitrilotriacetic acid as complexing agents

The leaching of zinc from zinc oxide dust was investigated in choline chloride-urea deep eutectic solvent (ChCl-urea DES) with the addition of nitrilotriacetic acid (NTA). The effect of important parameters on leaching process, such as leaching temperature, leaching time, liquid/solid ratio and NTA concentration was investigated and the optimization was done using surface response methodology (RSM) based on central composite design (CCD). The optimum condition for leaching of zinc from zinc oxide dust was identified to be a leaching temperature of 79.0 °C, a leaching time of 35.4 h, a liquid/solid ratio of 12.1 and an NTA concentration of 0.07 mol/L. A maximum of 87.9% of zinc was recovered under the optimum experimental conditions. The leaching process is controlled by diffusion and the corresponding activation energy is 26.2 kJ/mol. The resultant leaching solution was directly used for the electrodeposition of zinc, and pure zinc deposit is obtained.

NTA-assisted mineral element and lead transportation in Eremochloa ophiuroides (Munro) Hack.

Lead (Pb) is one of the most toxic and harmful pollutants to the environment and human health. Centipedegrass (Eremochloa ophiuroides (Munro) Hack.), an excellent ground cover plant for urban plant communities, exhibits the outstanding lead tolerance and accumulation. Nitrilotriacetic acid (NTA) is an environmentally friendly chelating agent that strengthens phytoremediation. This study explored the effects of different NTA concentrations on the absorption and transportation of mineral elements and Pb in centipedegrass. Following exposure to Pb (500μM) for 7days in hydroponic nutrient solution, NTA increased root Mg, K, and Ca concentrations and shoot Fe, Cu, and Mg concentrations and significantly enhanced the translocation factors of mineral elements to the shoot. Although NTA notably decreased root Pb absorption and accumulation, it significantly enhanced Pb translocation factors, and the Pb TF value was the highest in the 2.0mM NTA treatment. Furthermore, the shoot translocation of Pb and mineral elements was synergistic. NTA can support mineral element homeostasis and improve Pb translocation efficiency in centipedegrass. Regarding root radial transport, NTA (2.0mM) significantly promoted Pb transport by the symplastic pathway under the treatments with low-temperature and metabolic inhibitors. Meanwhile, NTA increased apoplastic Pb transport at medium and high Pb concentrations (200-800μM). NTA also enhanced the Pb radial transport efficiency in roots and thus assisted Pb translocation. The results of this study elucidate the effects of NTA on the absorption and transportation of mineral elements and Pb in plants and provide a theoretical basis for the practical application of the biodegradable chelating agent NTA in soil Pb remediation.

Evaluation of the Effects of Nitrilotriacetic Acid as a Chelating Agent on the Biochemical Toxicity of Lead in Oreochromis niloticus.

In the present research, the effects of sublethal lead (Pb) concentrations on total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI) levels, enzyme activities (aspartate transaminase, AST; alanine transaminase, ALT; lactate dehydrogenase, LDH), ion levels (magnesium, Mg; sodium, Na; potassium, K; chlorine, Cl; calcium, Ca), and some metabolite levels (cholesterol, triglyceride, HDL, LDL, albumin, total protein) in the blood serum of Oreochromis niloticus and the protective function of nitrilotriacetic acid (NTA) due to its chelating characteristic were investigated. O. niloticus, which has an important position in the food chain and is often preferred in toxicological studies, was exposed to 0.1ppm Pb, 0.1ppm Pb + 0.3ppm NTA, 1ppm Pb, and 1ppm Pb + 3ppm NTA concentrations for 7 and 21days. At the end of the duration, serum TAS and TOS levels were measured spectrophotometrically with Rel Assay Diagnostics; other enzyme activities, ion levels, and metabolite parameters were done by an autoanalyzer using commercial kits. Depending on the exposure periods and concentrations, the changes in the parameters were determined. It is determined that, under the influence of high ambient concentration of lead, TOS, OSI, AST, ALT, LDH, LDL, triglyceride, and Mg levels increased, while TAS, albumin, and K levels decreased after 21days. These increases/decreases in all serum biochemical parameters were generally higher in fish treated with Pb alone compared to fish treated with a mixture of Pb + NTA. This study shows that these changes in serum parameters could be used as an indicator to assess on metal toxicity.

Cubic tin sulfide thin films by a Sn-NTA system based chemical bath process

SnS films were prepared by a chemical bath deposition process in which the concentration of nitrilotriacetic acid, acting as the complexing agent, promoted an increase in film thickness, better grain connectivity, and the formation of single-phase cubic π-SnS. The optical and electrical studies in these films demonstrated that the enhancement of photosensitivity from 19.59 to 22.5 was associated with the elimination of the SnS2 phase, which consequently led to a band gap narrowing from 1.82 to 1.77 eV.

The Behavior of Cadmium Leaching from Contaminated Soil by Nitrilotriacetic Acid: Implication for Cd-Contaminated Soil Remediation

To determine the leaching behavior and mechanism of cadmium (Cd) from contaminated soil by nitrilotriacetic acid (NTA), batch leaching experiments and chemical extraction in combination with Fourier transform infrared spectroscopy (FTIR) analyses were conducted to investigate the changes of Cd species, the organic matter content, the functional groups of soil particles in the course of leaching. The batch experiment was conducted using one cadmium level (12.49 mg/kg), different levels of NTA (1, 5, 10, 100, 150, 200, 300, 400, and 500 mmol/L), different pH levels (6–11), and different contact times (10, 30, 60, 120, 240, 480, 1440 min). Moreover, based on the experiment results, factors like the input NTA concentration, the eluent pH values, as well as the leaching time for the amount of leached Cd were evaluated via a multiple linear regression simulation. The results showed that the leached Cd from contaminated soils increased with increasing input NTA concentration and absorbed NTA in soils. At the beginning of the leaching experiment, the functional groups of the soil particles changed from hydroxyl to ester, resulting in the release of Cd from soil particles. At the same time, the esterification reaction caused an increase of eluent pH. However, after Cd released into the liquid phase, the complexation reaction between NTA and Cd continually consumed NTA, and this resulted in a minor decrease in eluent pH. As the result, some amounts of Cd could be precipitated as Cd(OH)2 and immobilized again under high pH condition. Multiple linear regression results showed that the input NTA concentration is the main factor that influences the removal efficiency of Cd from contaminated soils. The study results provide vital support for the practice of Cd-contaminated soil remediation using NTA as chemical eluent.

Effects of a mixture of ligands on metal accumulation in diffusive gradients in thin films (DGT)

Environmental contextThe availability of trace metals to aquatic organisms is influenced by the natural ligands present in water. We investigate the influence of the composition of the system on the availability of metal cations as nutritive or toxic species. The focus is on clarifying whether availability measured in single-ligand systems with diffusive gradients in thin film devices can be used to predict accumulation in mixtures. AbstractNatural waters contain mixtures of ligands, which collectively affect the availability of trace metals. The individual contribution of each complex to the overall metal flux received by a sensor can be described in terms of its lability degree. The question arises as to whether the mixture entails specific non-additive effects, i.e. to what extent is it possible to predict the collective behaviour of the mixture from the values of the lability degree of each single ligand system (SLS). For this reason, a series of experiments with diffusion gradients in thin films (DGT) devices were carried out to measure nickel accumulation from synthetic media comprising either nitrilotriacetic acid (NTA), ethylenediamine (EN) or mixtures of both ligands. The results were compared with numerical simulations. It is shown that NiNTA becomes more inert in the mixture than in the SLS that contains the same concentration of free Ni and NiNTA, whereas the opposite is true for the Ni bound to EN, which becomes more labile in the mixture than in the SLS. This unprecedented behaviour arises when one of the ligands (NTA, forming strong and partially labile complexes) is present under non-excess conditions. As NiNTA and NiEN have an opposite influence on the lability degree of each other, the sum of partial fluxes calculated from the lability degrees obtained in SLSs yields a reasonable estimate of DGT performance in the mixture. Experimental accumulations in the mixture are just slightly below the predicted values, with errors lower than 11 % when NTA concentrations vary from 20 to 100 % of the total Ni concentration.

EDTA and NTA Effectively Tune the Mineralization of Calcium Phosphate from Bulk Aqueous Solution.

This study describes the effects of nitrilotriacetic acid (NTA) and ethylenediaminotetraacetic acid (EDTA) on the mineralization of calcium phosphate from bulk aqueous solution. Mineralization was performed between pH 6 and 9 and with NTA or EDTA concentrations of 0, 5, 10, and 15 mM. X-ray diffraction and infrared spectroscopy show that at low pH, mainly brushite precipitates and at higher pH, mostly hydroxyapatite forms. Both additives alter the morphology of the precipitates. Without additive, brushite precipitates as large plates. With NTA, the morphology changes to an unusual rod-like shape. With EDTA, the edges of the particles are rounded and disk-like particles form. Conductivity and pH measurements suggest that the final products form through several intermediate steps.

Effects of Nitrilotriacetic Acid on Anaerobic Co-Digestion of Food Waste and Sludge

The role of nitrilotriacetic acid (NTA) with the addition of four trace elements on mesophilic anaerobic co-digestion of food waste and sludge was investigated in batch reactor. Five different NTA concentrations (0, 8, 80, 800 and 8000 μM) were evaluated. The greatest coenzyme F420 content of five digester were 1.210 ± 0.210, 1.286 ± 0.179, 1.547 ± 0.187, 1.400 ± 0.222 and 0.955 ± 0.146 μmol L−1 during whole digestion process. The ultimate biogas yield of five digester were 198.1, 200.7, 239.7, 219.5 and 174.8 mL g−1-VSadded, respectively. The results indicated that the addition of NTA increased the biogas yield of anaerobic digester at an adequate concentration (around 80 μM).

Studies of Ternary Complexes of Zn (Il) Involving Aminocarboxylic Acids and NTA (Nitrilotriacetic Acid) by Paper Electrophoresis

Paper Electrophoresis study of mixed complexes of metal ions with 2-aminobenzoic acid, 3-aminobenzoic acid and 4-aminobenzoic acid as primary ligand and NTA as secondary ligand. Experimental procedure adopted for simple complexation studies is modified. The background electrolyte contains primary ligand in addition to perchloric acid and the pH is maintained at 8.5, the concentration of secondary ligand NTA is progressively increased and the electrophoretic observation of the metal ion spot on paper strip is taken at every addition of the secondary ligand, all the observations have been recorded under the Potential, 200 volts; Time, 30 min; Temperature, 25°C; Ionic strength, 0.1; Potential gradient; 6.66 volt/cm. Using the principle of average mobility, stability constant can be calculated with the help of mobilities. The higher values or stability constant of ternary complexes of 3-aminobenzoic acid than those of 4-aminobenzoic acid and 2-aminobenzoic acid and that of 4aminobenzoic acid than 2-aminobenzoic acid are attributed to the stronger acidic character of 3-aminobenzoic acid than 4-amino, and 2-aminobenzoic acid and that of 4-aminobenzoic acid than 2-aminobenzoic acid. It must be noted that higher values of stability constants in case of ternary complexes than binary complexes indicate their increased stability.

Leaching of low grade zinc oxide ores in NH4Cl–NH3 solutions with nitrilotriacetic acid as complexing agents

A novel method for leaching of low grade zinc oxide ores in NH4Cl–NH3 solutions containing nitrilotriacetic acid (NTA) as complexing agents is proposed in this paper. The influences of NTA concentration, leaching temperature, stirring speed, particle size and liquid–solid ratio on the zinc extraction are discussed. It is found that the addition of NTA facilitates the zinc extraction. Under the condition that particle size is 64–71μm, NTA concentration is 0.1mol/L, liquid–solid ratio is 20mL/g, leaching temperature is 40°C and stirring speed is 400rpm, the zinc extraction reaches 90.3%. The result of leaching kinetic study indicates that the leaching process is controlled by the interface transfer and diffusion through the product layer and the corresponding activation energy is 22.3kJ/mol.

Chelate-enhanced phytoextraction and phytostabilization of lead-contaminated soils by carrot (Daucus carota)

The objective of this study was to study the influence of different ethylenediamine tetraacetate (EDTA), nitrilotriacetic acid (NTA) and oxalic acid (HOx) concentrations on tolerance and lead (Pb) accumulation capacity of carrot (Daucus carota). The results indicated that by increasing Pb, NTA and HOx concentrations in the soil, the shoot, taproot and capillary root dry matters increase effectively. In contrary, EDTA caused to reduce capillary roots biomass. EDTA was more effective than NTA and HOx in solubilizing soil Pb. The highest Pb content in shoots (342.2 ± 13.9 mg kg−1) and taproots (301 ± 15.5 mg kg−1) occurred in 10 mM EDTA, while it occurred for capillary roots (1620 ± 24.6 mg kg−1) in 5 mM HOx, when the soil Pb concentration was 800 mg kg−1. The obtained high phytoextraction and phytostabilization potentials were 1208 (±25.6) and 11.75 (±0.32) g Pb ha−1 yr−1 in 10 mmol EDTA kg−1 soil and no chelate treatments, respectively. It may be concluded that chelate application increases Pb uptake by carrots. Consequently, this plant can be introduced as a hyperaccumulator to phytoextract and phytostabilize Pb from contaminated soils.

Enhanced heterogeneous and homogeneous Fenton-like degradation of carbamazepine by nano-Fe3O4/H2O2 with nitrilotriacetic acid

The influence of a biodegradable agent, nitrilotriacetic acid (NTA), on the degradation of the model compound carbamazepine (CBZ) by the nano-Fe3O4/H2O2 system was investigated. The results showed that the presence of NTA can provide better performance of the nano-Fe3O4/H2O2 system for CBZ degradation at reduced usage of H2O2 and nano-Fe3O4. The optimal concentration of NTA was determined to be 0.5–1.0mM. The first-order rate constant, kapp, for CBZ degradation by 1.0gL−1 of nano-Fe3O4 and 100mM of H2O2 in the presence of 0.5mM of NTA at an initial neutral pH was determined to be 4.32×10−2min−1, which was 80 times larger than that in the absence of NTA. In addition, the kapp value increased with the increase in nano-Fe3O4 concentration from 0.1 to 3.0gL−1, and the H2O2 concentration increased from 5 to 600mM. The initial pH of CBZ solutions over a range of pH 5.0–9.0 did not affect the kapp value of CBZ (p=0.08). A decrease in the initial concentration of CBZ from 6.35×10−2 to 1.06×10−2 mM resulted in an increase of the kapp value from 4.32×10−2 to 1.51×10−1min−1. Moreover, the results indicated that the degradation intermediates were generated by the attack of OH. The degradation mechanism of CBZ included both an enhanced heterogeneous Fenton-like reaction on the Fe3O4 nanoparticle surface and an enhanced homogeneous Fenton-like reaction in the aqueous phase by Fe-NTA complexes.

New electroless copper plating bath using sodium hypophosphite as reductant

In this paper, a new environment friendly electroless plating bath using sodium hypophosphite as reductant and nitrilotriacetic acid as complexing agent was investigated under the acid condition. The effects of bath temperature, pH, CuSO4.5H2O concentration, nitrilotriacetic acid concentration and NaH2PO2.H2O concentration upon the deposition rate and the bath stability were studied. The electrochemical results indicated that the deposition rate of the electroless copper increased with the decrease in the pH, and it reached 2·4 μm h−1 when the bath pH was 6·0. The as deposited Cu films were characterised by energy dispersive X-ray analyser, X-ray diffraction, atomic force microscopy and resistivity measurement. The quality of the Cu films were improved by the addition of a surfactant PEG-600, and a uniform copper film with a low resistivity (2·60 μΩ cm) was obtained, which was able to be used as seed layer for electroplating Cu.

Can Nitrilotriacetic Acid (NTA) Act as a Habit Modifier for Rock Salt Crystals? An Answer from Computational and Experimental Studies

It has been reported that nitrilotriacetic acid (NTA) has no effect on the growth habit of sodium chloride. We report here that NTA acts as a habit modifier for rock salt. The concentration of NTA required to influence the habit of salt crystals from cubic to octahedron is much less compared to the concentrations of other organic additives used for this purpose. The influence of NTA under different pH conditions toward the morphology of sodium chloride crystals has been investigated by experimental and computational methods. Prior to any analysis, a conformational search of NTA and its three dissociated forms was performed with molecular mechanics MM2* and DFT (B3LYP/6-31+G*) methods in aqueous phase. The low energy conformers were used to derive quantum chemically molecular electrostatic potential (MESP) to examine the possible sites of interaction for NTA and its dissociated forms with the important planes of NaCl. Three dimensional (3D)-slab model calculations performed to mimic the surfaces of sodium ...

Bacterial Pu(V) reduction in the absence and presence of Fe(III)–NTA: modeling and experimental approach

Plutonium (Pu), a key contaminant at sites associated with the manufacture of nuclear weapons and with nuclear-energy wastes, can be precipitated to "immobilized" plutonium phases in systems that promote bioreduction. Ferric iron (Fe(3+)) is often present in contaminated sites, and its bioreduction to ferrous iron (Fe(2+)) may be involved in the reduction of Pu to forms that precipitate. Alternately, Pu can be reduced directly by the bacteria. Besides Fe, contaminated sites often contain strong complexing ligands, such as nitrilotriacetic acid (NTA). We used biogeochemical modeling to interpret the experimental fate of Pu in the absence and presence of ferric iron (Fe(3+)) and NTA under anaerobic conditions. In all cases, Shewanella alga BrY (S. alga) reduced Pu(V)(PuO(2) (+)) to Pu(III), and experimental evidence indicates that Pu(III) precipitated as PuPO(4(am).) In the absence of Fe(3+) and NTA, reduction of PuO(2) (+) was directly biotic, but modeling simulations support that PuO(2) (+) reduction in the presence of Fe(3+) and NTA was due to an abiotic stepwise reduction of PuO(2) (+) to Pu(4+), followed by reduction of Pu(4+) to Pu(3+), both through biogenically produced Fe(2+). This means that PuO(2) (+) reduction was slowed by first having Fe(3+) reduced to Fe(2+). Modeling results also show that the degree of PuPO(4(am)) precipitation depends on the NTA concentration. While precipitation out-competes complexation when NTA is present at the same or lower concentration than Pu, excess NTA can prevent precipitation of PuPO(4(am)).

Redox behavior of Ce(IV)/Ce(III) in the presence of nitrilotriacetic acid: A surrogate study for An(IV)/An(III) redox behavior

AbstractUsing cyclic voltammetry, we investigated the redox behavior of Ce(IV)/Ce(III), which is a surrogate for An(IV)/An(III) (An=actinides), in a solution of nitrilotriacetic acid (NTA) at 25 °C. The cyclic voltammogram of Ce in a 0.1 M NTA solution at pH 6 showed a reversible one-electron redox reaction for Ce(IV)/Ce(III) at 0.51 Vvs.Ag/AgCl. This redox potential was much lower than that obtained in 1 M nitric acid, indicating that Ce(IV) was preferentially stabilized by complexation with NTA. The redox potential in the NTA solution was independent of the Ce concentration from 2 to 20 mM, NTA concentration from 5 to 200 mM and pH between 3 and 7. These results indicated that no polymerization and no additional coordination of NTA and OH−to the Ce(III)-NTA complex took place during the redox reaction. As the speciation calculation of Ce(III) in the NTA solution showed that the predominant species was CeIII(nta)23−(H3nta=NTA), the redox reaction of the Ce-NTA complex was expressed by the following: CeIV(nta)22−+e−⇋CeIII(nta)23−. The logarithm of the stability constant of CeIV(nta)22−was calculated to be 38.6±0.8 forI=0 from the redox potential shift of Ce(IV)/Ce(III) in the NTA solution. The value was in good accordance with the stability constant of the NpIV(nta)22−complex, demonstrating that the aqueous coordination chemistry of Ce(IV) with NTA is quite similar to that of An(IV). These results strongly suggest that a negative shift of the Pu(IV)/Pu(III) redox potential in the NTA solution should make Pu(IV) more stable than Pu(III) even in a reducing environment.