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Co-transport of U(VI) and akaganéite colloids in water-saturated porous media: Role of U(VI) concentration, pH and ionic strength
- Source :
- Water research. 147
- Publication Year :
- 2018
-
Abstract
- Remediating uranium contamination becomes a worldwide interest because of increasing uranium release from mining activities. Due to ubiquitous presence of pyrite and the application of iron-based technology, colloidal iron oxy-hydroxides such as akaganeite colloid (AKC) extensively exist in uranium polluted water at uranium tailing sites. In this context, we studied individual and co-transport of U(VI) and AKC in water-saturated sand columns at 50 mg/L AKC and environmentally relevant U(VI) concentrations (5.0 × 10−7 ∼ 5.0 × 10−5 M). It was found that, in addition to the impact of pH and ionic strength, whether AKC facilitated U(VI) transport depended on U(VI) concentration as well. The presence of AKC facilitated U(VI) transport at relatively low U(VI) concentration (5.0 × 10−7 ∼ 5.0 × 10−6 M), which was due to the strong adsorption of U(VI) on AKC and faster transport of AKC than that U(VI) as observed in their individual transport experiments. At relatively high U(VI) concentrations (5.0 × 10−5 M), however, AKC impeded U(VI) transport because U(VI) of high concentration decreased AKC colloidal stability and increased AKC aggregation and attachment. Thus, U(VI) and AKC co-transport was even blocked completely at relatively high pH and ionic strength. The mechanisms behind the co-transport of U(VI) and AKC were also confirmed by assessing the evolutions of aqueous pH and AKC zeta potential and particle size distribution in the column effluents. A two-site non-equilibrium model and a two-site kinetic attachment/detachment model well-described the breakthrough curves of U(VI) and AKC, respectively. Knowledge generated from this study provides a thorough understanding of uranium transport in the absence/presence of AKC, and brings new insights into the influence of contaminant concentration on co-transport in the presence of colloids.
- Subjects :
- Environmental Engineering
Akaganéite
0208 environmental biotechnology
Inorganic chemistry
Concentration effect
chemistry.chemical_element
Context (language use)
02 engineering and technology
010501 environmental sciences
engineering.material
01 natural sciences
Ferric Compounds
Colloid
Adsorption
Colloids
Waste Management and Disposal
0105 earth and related environmental sciences
Water Science and Technology
Civil and Structural Engineering
Aqueous solution
Ecological Modeling
Osmolar Concentration
Water
Uranium
Hydrogen-Ion Concentration
Pollution
020801 environmental engineering
chemistry
Ionic strength
engineering
Porosity
Subjects
Details
- ISSN :
- 18792448
- Volume :
- 147
- Database :
- OpenAIRE
- Journal :
- Water research
- Accession number :
- edsair.doi.dedup.....cb679f966674a59fec6f28cf9f9b2f6e