Co-transport of U(VI), humic acid and colloidal gibbsite in water-saturated porous media

Yang, Junwei; Ge, Mengtuan; Jin, Qiang; Chen, Zongyuan; Guo, Zhimou

doi:10.1016/j.chemosphere.2019.05.091

Cited by 33 publications

(3 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, at high pH, the hydrophilicity of the HAs is enhanced, exposing charged carboxylate groups, which can directly coordinate with the ions of heavy metals. However, as the propensity for HA to aggregate at near-neutral pH is lower, although the metal ions would be more tightly bound to HA, the overall rate at which ions might migrate through the system may well be greater. − The form of HA in groundwater is believed to affect the ability of HA to bind to and transport heavy metal ions, and so groundwater pH could potentially be used to modulate HA-based remediation strategies of contaminated sites.…”

Section: Resultsmentioning

confidence: 99%

Understanding the Effect of pH on the Solubility and Aggregation Extent of Humic Acid in Solution by Combining Simulation and the Experiment

Lan

Liu

et al. 2022

Environ. Sci. Technol.

View full text Add to dashboard Cite

Molecular dynamics (MD) simulations were performed to investigate the dynamics of humic acid (HA) in an aqueous solution and the influence of pH, temperature, and HA concentration. The HA model employed in MD simulations was chosen and validated using experimental chemical composition data and Fourier transform infrared (FTIR) spectra. The simulations showed that the HA molecule has a strong propensity to adopt a compact conformation in water independent of pH, while the aggregation of HA was found to be pH-dependent. At high pH, the ionized HAs assembled into a thread-like structure, maximizing contact with water. At low pH, the neutral HAs formed a droplet-like aggregate, minimizing contact with the solvent. The simulation results are consistent with experimental data from dynamic light scattering (DLS) measurements and transmission electron microscopy (TEM) imaging. This work provides new insight into the folding and aggregation of HA as a function of pH and a molecular-level understanding of the relationship between the acidity and the structure, solubility, and aggregation of HA, with direct implications for HA-based remediation strategies of contaminated sites.

show abstract

Section: Resultsmentioning

confidence: 99%

Understanding the Effect of pH on the Solubility and Aggregation Extent of Humic Acid in Solution by Combining Simulation and the Experiment

Lan

Liu

et al. 2022

Environ. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…, UO 2 (CO 3 ) 3 4− , UO 2 CO 3 (aq), etc [8][9][10] . Second, calcium and alkaline earth metal ions in the environment, rocks and soil rich in carbonate minerals, after the erosion of rainwater and river water, some carbonate minerals will be washed into small particles, the surface portion will dissolve at the same time [11] .…”

Section: −mentioning

confidence: 99%

Adsorption of U(VI) onto Amidoxime-functionalized Hydrothermal Carbon in the Presence of Ca-U(VI)-CO3 Complexes

Dong¹,

Zhang²,

Zhou³

et al. 2020

Res. Appl. Mater. Sci.

View full text Add to dashboard Cite

The aim is collecting uranium from groundwater in which uranium mainly exists in negative species, the amidoxime-functionalized hydrothermal carbon (AO-HTC) was synthesized. From the results of N2 adsorption-desorption and SEM, AO-HTC is a small spherical surface; FT-IR and Elemental analysis showed that the amidoxime group was successfully grafted onto the surface of the material; Zeta-potential measurement showed that the amino nitrogen atom is protonated in the oxime group. The optimum pH value of AO-HTC for uranium adsorption is 6.0, and the adsorption equilibrium is reached within 80 min, which is in accordance with the pseudo-second order adsorption kinetic model. The adsorption of uranium by AO-HTC accords with the Langmuir isotherm adsorption model, and the single-layer saturated adsorption capacity is 254.13mg·g-1. The thermodynamic parameters calculated by the adsorption isotherm indicate that AO-HTC adsorption of uranium is a spontaneous endothermic chemical process and Carbonate ion, calcium ion and humic acid concentration have great influence on uranium adsorption. The experiments results show that AO-HTC has the potential to elimination of U(VI) from groundwater.

show abstract

“…The present study seeks to improve the fundamental understanding of nonclassical growth pathways that may underpin crystallization of gibbsite (α-Al(OH) 3 ). Gibbsite is a ubiquitous soil mineral, where it can act as an important sorbent of toxic or radioactive elements. − Gibbsite is also the dominant mineral in bauxite deposits, the major ore for aluminum (Al) production. Crystallization of gibbsite under alkaline conditions is relevant to bauxite formation from lateritic weathering of ultrabasic rock, bauxite processing via the Bayer process, and for the processing of Cold War nuclear waste. − Under the current nuclear waste retrieval plan, gibbsite dissolution will be achieved using alkaline solutions with excess sodium hydroxide.…”

Section: Introductionmentioning

confidence: 99%

Isotopic Substitution Reveals the Importance of Aluminate Diffusion Dynamics in Gibbsite (Al(OH)₃) Crystallization from Alkaline Aqueous Solution

Krzysko

Graham

Dembowski

et al. 2022

ACS Earth Space Chem.

View full text Add to dashboard Cite

Understanding molecular-scale factors governing the precipitation of aluminum hydroxides, such as gibbsite, under alkaline conditions is important for the formation of laterite deposits, as well as aluminum processing. However, mechanisms enabling tetrahedral aluminate ions to assemble into octahedral sites of the gibbsite lattice remain unclear. Formation of oligomeric complexes has been hypothesized as a critical intermediate step. Here, we report a study of gibbsite solubility in highly alkaline solutions using deuterium substitution to probe equilibrium and kinetic factors that could affect oligomeric intermediate formation, including the reactivity and the diffusivity of aluminate ions. When substituting sodium hydroxide with sodium deuteroxide, solution analysis shows a nearly 40% and 50% increase in gibbsite solubility in 2.4 and 3.3 mol·kg–1 total sodium solutions, respectively. Raman spectroscopy indicated that monomeric aluminate ions are the predominant species in solution irrespective of deuteration. However, both 27Al and 23Na nuclear magnetic resonance (NMR) spectroscopy revealed significant differences in chemical shifts in deuterated solutions, and analysis of 1H, 23Na, and 27Al diffusion coefficients with pulsed-field gradient, stimulated echo NMR spectroscopy shows a decrease in ion diffusivity with increasing total deuterium in solution, consistent with the notion of increasing strength in the hydrogen/deuterium bonding network. Because the relative change in 1H diffusion coefficients are commensurate with the difference in apparent solubility constants, there is evidence for an oligomeric intermediate whose steady-state concentration is maintained by the collision frequency of aluminate ions.

show abstract

Co-transport of U(VI), humic acid and colloidal gibbsite in water-saturated porous media

Cited by 33 publications

References 57 publications

Understanding the Effect of pH on the Solubility and Aggregation Extent of Humic Acid in Solution by Combining Simulation and the Experiment

Understanding the Effect of pH on the Solubility and Aggregation Extent of Humic Acid in Solution by Combining Simulation and the Experiment

Adsorption of U(VI) onto Amidoxime-functionalized Hydrothermal Carbon in the Presence of Ca-U(VI)-CO3 Complexes

Isotopic Substitution Reveals the Importance of Aluminate Diffusion Dynamics in Gibbsite (Al(OH)₃) Crystallization from Alkaline Aqueous Solution

Contact Info

Product

Resources

About

Co-transport of U(VI), humic acid and colloidal gibbsite in water-saturated porous media

Cited by 33 publications

References 57 publications

Understanding the Effect of pH on the Solubility and Aggregation Extent of Humic Acid in Solution by Combining Simulation and the Experiment

Understanding the Effect of pH on the Solubility and Aggregation Extent of Humic Acid in Solution by Combining Simulation and the Experiment

Adsorption of U(VI) onto Amidoxime-functionalized Hydrothermal Carbon in the Presence of Ca-U(VI)-CO3 Complexes

Isotopic Substitution Reveals the Importance of Aluminate Diffusion Dynamics in Gibbsite (Al(OH)3) Crystallization from Alkaline Aqueous Solution

Contact Info

Product

Resources

About

Isotopic Substitution Reveals the Importance of Aluminate Diffusion Dynamics in Gibbsite (Al(OH)₃) Crystallization from Alkaline Aqueous Solution