The dissolution rates of unirradiated UO and unirradiated UO doped with GdO were determined as a function of pH using flow-through experiments in the presence of O(g) and bicarbonate. The dissolution rate of non-doped UO was very low under hyperalkaline conditions (pH 12-13) whereas it increased drastically as the pH decreased to 9. The dissolution of non-doped UO in the pH range of 9-13 was consistent with the oxidative dissolution mechanism already described for UO dissolution in the presence of bicarbonate and oxygen. XPS analysis performed on the solid after dissolution experiments at pH 10 and 13 supported the bicarbonate effect to complex UO and accelerate dissolution. Moreover, UO doped with GdO (5 wt% and 10 wt%) showed dissolution rates as low as non-doped UO under hyperalkaline conditions, which were maintained throughout the pH range studied (9-13). No substantial differences in the dissolution rates between these two doping levels were found. XPS analysis evidenced a similar surface composition both at pH 10 and 13, with U(V) being the dominant oxidation state. The low dissolution rates were assumed to be a consequence of the gadolinium capacity to retard the oxidation of U(V) to U(VI). The slight increase in dissolution rates observed in the hyperalkaline region was attributed to a shift in the oxidative dissolution mechanism, in which the presence of OH promotes the formation of soluble uranyl hydroxo complexes.
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http://dx.doi.org/10.1039/d3dt01268a | DOI Listing |
Huan Jing Ke Xue
January 2025
College of Hydraulic and Civil Engineering, Xinjiang Agricultural University, Urumqi 830052, China.
To explore the changes in groundwater hydrochemistry and its source influence in the low water level period of the southern oasis area of Gaochang District, Turpan City before and after the management of groundwater overexploitation, based on 12 groups of water samples in 2016 (three groups of unconfined water, nine groups of confined water) and 18 groups of water samples in 2023 (five groups of unconfined water, thirteen groups of confined water), mathematical statistics, hydrochemical diagraph, hydrogen and oxygen isotope means, and an absolute principle component-multiple linear regression (APCS-MLR) model were used to analyze the changes and sources of groundwater hydrochemistry. The results showed that due to the dynamic conditions of groundwater, the dominant cation changed from Na to Ca, and the anion changed from HCO to SO. The dominant cation of confined water changed from Ca to Na, and the dominant anion remained unchanged as SO.
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Institute of Soil and Water Conservation CAS&MWR, Yangling 712100, China; College of Soil and Water Conservation Science and Engineering, Northwest A&F University, Yangling 712100, China. Electronic address:
Agricultural soils face severe challenges, including water scarcity and heavy metal contamination. Optimizing soil remediation efficiency while minimizing inputs is essential. This study assessed the water retention and heavy metal adsorption properties of L-PH hydrogel through aqueous experiments.
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School of Environmental, Civil, Agricultural and Mechanical Engineering, University of Georgia, Athens 30602, Georgia, United States.
This study investigated the speciation and aqueous dissolution of macronutrients in fire ash from diverse ecosystems and speciation of ash and smoke from laboratory burning, exploring the variations and their causes. The speciation of phosphorus (P), calcium (Ca), and potassium (K) in fire ash from five globally distributed ecosystems was characterized by using X-ray absorption spectroscopy and sequential fractionation. Aqueous dissolution of the macronutrients was measured by batch experiments at acidic and alkaline pHs.
View Article and Find Full Text PDFACS Omega
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Key Laboratory for Enhanced Oil & Gas Recovery of the Ministry of Education, Northeast Petroleum University, Daqing 163318, Heilongjiang, China.
In alkali/surfactant/polymer (ASP) flooding systems, alkalis react with clay minerals such as Illite, montmorillonite, and kaolinite, leading to reservoir damage and impacting oil recovery rates. Therefore, studying the dissolution effects of strong alkalis on clay minerals is crucial for improving oil recovery. This study uses Illite as a representative clay mineral and employs the ReaxFF reactive force field and molecular dynamics simulations to model its dissolution in NaOH solution.
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Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning Province 110016, PR China. Electronic address:
Mesoporous carriers have gained significant attention for enhancing the solubility and bioavailability of Biopharmaceutics Classification System (BCS) Class II drugs. However, the contribution of mesoporous carriers with varying morphologies to the physical stability of these drugs is not well-defined. In this work, mesoporous carbon nanoparticles (MCN) and hollow carbon mesoporous nanoparticles (HMC) were prepared, while the weakly acidic Indomethacin (IMC) and alkaline Celecoxib (CXB) were incorporated into these carriers in the amorphous state by the solvent evaporation method.
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