Electrochemical Studies and XPS Analysis of the Surface of Zirconium-702 in Concentrated Nitric Acid With and Without Fluoride Ions

Jayaraj, J.; Krishna, D. Nanda Gopala; Mallika, C.; Mudali, U. Kamachi

doi:10.1007/s12666-017-1165-z

Cited by 11 publications

(7 citation statements)

References 29 publications

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“…In addition, the XPS spectra of the fresh and used HZO@D201 are compared in Figure e, and they were almost identical to each other, except for the new peaks corresponding to S 2s (∼229 eV) and 2p (∼167 eV) peaks in the used HZO@D201, arising from ion exchange between Cl – and SO 4 2– . With respect to the high-resolution XPS Zr 3d spectra, the bands at 182.5 and 184.9 eV in the fresh HZO@D201 corresponded to the 5/2 and 3/2 peaks of the Zr–O bond, respectively (Figure f) . A shift of 0.3 eV occurred in the Zr 3d spectra after fluoride uptake, mainly arising from the strong interaction between HZO and fluoride.…”

Section: Resultsmentioning

confidence: 95%

“…With respect to the high-resolution XPS Zr 3d spectra, the bands at 182.5 and 184.9 eV in the fresh HZO@D201 corresponded to the 5/2 and 3/2 peaks of the Zr−O bond, respectively (Figure 7f). 60 A shift of 0.3 eV occurred in the Zr 3d spectra after fluoride uptake, mainly arising from the strong interaction between HZO and fluoride. Moreover, two new bands appeared at around 184.0 eV and 186.4 eV, due to the formation of the Zr−F bond.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

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Pilot-Scale Field Demonstration of Environmental Nanotechnology for Groundwater Defluoridation

Deng

Cheng

et al. 2022

ACS EST Eng.

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Fluoride contamination in groundwater is a global issue. Nanoscale oxides of Zr(IV), Al(III), and Ti(IV) can form the inner-sphere complex with fluoride through ligand exchange, offering a new chance for efficient groundwater purification. However, pilot-scale field demonstration of nanotechnology in groundwater defluoridation is very rare. Herein, we conducted a 150-day field defluoridation study using the nanocomposite HZO@D201, which was prepared by encapsulating nano-hydrated zirconium oxide (HZO) inside the strongly basic anion exchanger D201. The HZO@D201 beads were packed in five-stage series columns (40 L for each column), and the groundwater was pumped through the columns sequentially. The effective treatment amount for the single column ([F–] < 1.0 mg/L) exceeded ∼3000 bed volume (BV). The exhausted HZO@D201 was fully refreshed through ex situ treatment with NaOH–NaCl solution for repeated use without significant loss in defluoridation reactivity. Owing to the specific interaction with HZO, the fluoride concentration could be steadily reduced below 1.0 mg/L throughout the 150-day field demonstration, while the common anions coexisting in groundwater (K+, Na+, Ca2+, Mg2+, SO4 2–, Cl–, etc.) remained almost unchanged. The operational cost for deep defluoridation was estimated as 0.574 RMB per ton of groundwater, much less than that of the widely studied reverse osmosis. TEM, XPS, and Fourier transform infrared (FTIR) analysis indicated that negligible change occurred in the structure and chemical composition of HZO@D201 after the long-term field assay. This study may inspire more attempts at the pilot scale and engineering demonstration of nano-enabled water treatment techniques.

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Section: Resultsmentioning

confidence: 95%

Section: ■ Materials and Methodsmentioning

confidence: 99%

Pilot-Scale Field Demonstration of Environmental Nanotechnology for Groundwater Defluoridation

Deng

Cheng

et al. 2022

ACS EST Eng.

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“…30,31 The charged species of Zr can be an oxide or oxyfluoride or fluoride. In earlier publications, the binding energy of Zr-oxide (Zr 2 O 3 -3d 5/2 ) was reported to be present at 182.6 eV, 32 and that of zirconium oxyfluoride (Zr 0.332 O 0.639 F 0.021 -3d 5/2 ) was reported at 182.5 eV. 33 These values are close to the binding energy values (182.66 eV) obtained for Zr 3+ (3d 5/2 ) in this study.…”

Section: Resultsmentioning

confidence: 99%

Mechanistic Analysis of Anodic Dissolution of Zr in Acidic Fluoride Media

Amrutha

Rao

Ramanathan

2018

J. Electrochem. Soc.

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Anodic dissolution of Zr in 10 mM HF was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. The surface state of the electrode was analyzed using X-ray photon spectroscopy, and the surface morphology was characterized using atomic force microscopy. EIS data acquired at multiple dc potentials were subjected to mechanistic analysis. Reaction mechanism analysis approach reveals that at least four intermediates are required to describe the observed results. The intermediates are likely to be Zr sub-oxides, oxyfluorides and ZrO 2 . The proposed mechanism successfully predicts the major features observed in polarization and impedance spectra. At low overpotentials, the fractional surface coverage of Zr 3+ species is higher than that of Zr 4+ species, and the electrochemical dissolution rate is higher than the chemical dissolution rate. As the overpotential increases, the surface is covered with Zr 4+ species and chemical dissolution rate becomes comparable to electrochemical dissolution rate. Although the surface is covered with Zr 4+ species at higher overpotentials, significant chemical and electrochemical dissolution processes continue to occur and hence Zr is not protected in acidic fluoride media under anodic conditions. © The Author Zirconium and alloys containing Zr are extensively used in the nuclear power industry as fuel cladding agents, in chemical industries as an alloying component, and in biomedical implants.1-4 The wide acceptance of this metal and its alloys is due to their superior mechanical strength, and high resistance toward corrosion, and H 2 embrittlement.5-8 These properties are due to the formation of a stable, protective passive film of ZrO 2 .9-11 Although Zr exhibits excellent corrosion resistance in most of the harsh environments, it readily dissolves in acidic fluoride media. 6,7,12,13 Earlier scientific reports on Zr dissolution are mostly based on conventional techniques, such as weight loss measurements, 14 measurement of volume of H 2 gas evolved, 7 and steady-state polarization techniques.15 Prono et al. 16 have analyzed the polarization of Zr in 0.12 M NaF + 7 M HNO 3 and proposed a seven-step mechanism comprising three competitive paths to describe the dissolution. This analysis was limited to the modeling of polarization data obtained at a single concentration. In our previous work, Zr anodic dissolution mechanism in the acidic fluoride medium was studied using the mechanistic analysis of current potential polarization data in various HF solutions.17 A mechanism containing two adsorbed intermediates and two dissolution steps, shown in Eq. 1, was proposed. The model successfully predicted the major characteristics of the polarization curves, and the results predicted that the chemical and the electrochemical dissolution steps were affected by the concentration of HF − 2 and HF, respectively. Anodic dissolution of other valve metals such as Ti 18,19 and Nb 20 have been characterized using potentiodynamic polarization and electrochemical imped...

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“…However, zirconium and titanium exhibited high corrosion resistance in boiling nitric acid, but showed poor corrosion in nitric acid containing fluoride ions [3,5]. It was confirmed that the corrosion of zirconium was attributed to the formation of ZrOF 2 and ZrF 4 [3,5]. Ti exhibited high corrosion resistance than zirconium alloy when exposed to boiling nitric acid containing fluoride ions with ZrO(NO 3 ) 3 as complexing agent [3].…”

Section: Introductionmentioning

confidence: 90%

“…0.05 M NaF was proposed for the dissolution of spent mixed oxide (72%UO 2 -28%PuO 2 ) fuels, [3] and the addition of fluoride ions is highly necessary for its complete dissolution [4]. However, zirconium and titanium exhibited high corrosion resistance in boiling nitric acid, but showed poor corrosion in nitric acid containing fluoride ions [3,5]. It was confirmed that the corrosion of zirconium was attributed to the formation of ZrOF 2 and ZrF 4 [3,5].…”

Section: Introductionmentioning

confidence: 99%

Studies on Corrosion of Titanium and Air-Oxidized Titanium in Fluorinated Nitric Acid

Jayaraj

Padinhateeri

Ningshen

et al. 2019

Trans Indian Inst Met

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Titanium (Ti) is a lustrous transition metal which possesses excellent corrosion resistance in several aggressive environments but is attacked by acidic fluoride media. In this work, the addition of fluoride ion to nitric acid on the corrosion behavior of Ti and air-oxidized Ti was studied. Air oxidation of Ti at 800°C for 5 h resulted in the formation of an intact rutile TiO 2 layer with a thickness of about 35 lm. The corrosion resistance was investigated from the polarization resistance (R P ) values which were obtained from linear polarization and electrochemical impedance spectroscopy (EIS) measurements. A decrease in the R P value of Ti with the addition of fluoride ion in nitric acid was observed, and this indicated the formation of an unstable layer, which resulted in accelerated dissolution. The several order increase in the R P value of air-oxidized Ti in nitric acid containing fluoride ions pointed the improved resistance to corrosion. The diffusivity of species through the air-oxidized TiO 2 layer was estimated from the electrochemical equivalent circuit (EEC) analysis of EIS data. Even though the diffusivity increased by several orders with the addition of fluoride ions, air-oxidized Ti provided better protection against nitric acid containing fluoride ions than Ti. The corrosion rates of Ti and air-oxidized Ti in boiling nitric acid containing fluoride ions were also estimated from weight loss experiments. Even in boiling fluorinated nitric acid, airoxidized Ti provided better corrosion protection, with corrosion rates of about 1000 times less than that of Ti.

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Electrochemical Studies and XPS Analysis of the Surface of Zirconium-702 in Concentrated Nitric Acid With and Without Fluoride Ions

Cited by 11 publications

References 29 publications

Pilot-Scale Field Demonstration of Environmental Nanotechnology for Groundwater Defluoridation

Pilot-Scale Field Demonstration of Environmental Nanotechnology for Groundwater Defluoridation

Mechanistic Analysis of Anodic Dissolution of Zr in Acidic Fluoride Media

Studies on Corrosion of Titanium and Air-Oxidized Titanium in Fluorinated Nitric Acid

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