scholarly journals Dissolution of poorly soluble uranyl phosphate phases in the Metaautunite Subgroup under uranyl peroxide cage cluster forming conditions

2020 ◽  
Vol 105 (2) ◽  
pp. 182-193 ◽  
Author(s):  
Haylie L. Lobeck ◽  
Enrica Balboni ◽  
Connor J. Parker ◽  
Tsuyoshi A. Kohlgruber ◽  
Mengyu Xu ◽  
...  
Keyword(s):  
Groundwater Remediation ◽  
Uranium Deposits ◽  
Experimental Conditions ◽  
Tetraethylammonium Hydroxide ◽  
Remediation Strategies ◽  
Uranyl Phosphate ◽  
Poorly Soluble ◽  
Uranyl Phosphates ◽  
Low Solubility ◽  
Anionic Sheet

Abstract Uranyl phosphate minerals are widespread in uranium deposits and normally exhibit very low solubility in aqueous systems. Uranyl phosphates of the autunite group and metaautunite subgroup impact the mobility of uranium in the environment and have inspired groundwater remediation strategies that emphasize their low solubility. The importance of soluble uranium-bearing macro-anions, including nanoscale uranyl peroxide cage clusters, is largely unexplored relative to solubilization of normally low-solubility uranium minerals. Eight synthetic analogs of metaautunite subgroup minerals have been prepared and placed in various alkaline aqueous solutions containing hydrogen peroxide and tetraethylammonium hydroxide. Each uranyl phosphate studied has a topologically identical anionic sheet of uranyl square bipyramids and phosphate tetrahedra combined with various cations (Li+, Na+, K +, Rb+, Cs+, Mg2+, Ca2+, Ba2+) and water in the interlayer. Uranyl peroxides formed under many of the experimental conditions examined, including solid studtite [(UO2)(O2)(H2O)2](H2O)2 and soluble uranyl peroxide cage clusters containing as many as 28 uranyl ions. Uranyl phosphate solids in contact with solutions in which uranyl peroxide cage clusters formed dissolved extensively or completely. The greatest dissolution of uranyl phosphates occurred in systems that contained cations with larger hydrated radii, Li+ and Na+. The details of the uranium speciation in solution depended on the pH and counter cations provided from the interlayers of the uranyl phosphate solids.

Solubility Enhancement of Poorly Soluble Drug Simvastatin by Solid Dispersion Technique

2016 ◽  
Vol 2 (2) ◽  
pp. 91-95
Author(s):  
Neelima Rani T ◽  
Pavani A ◽  
Sobhita Rani P ◽  
Srilakshmi N
Keyword(s):  
Dissolution Rate ◽  
Drug Carrier ◽  
Solid Dispersions ◽  
Aqueous Solubility ◽  
Onset Of Action ◽  
Kneading Method ◽  
Wetting Property ◽  
Poorly Soluble ◽  
Dispersion Technique ◽  
Low Solubility

This study aims to formulate solid dispersions (SDs) of Simvastatin (SIM) to improve the aqueous solubility, dissolution rate and to facilitate faster onset of action. Simvastatin is a BCS class II drug having low solubility & therefore low oral bioavailability. In the present study, SDs of simvastatin different drug-carrier ratios were prepared by kneading method. The results showed that simvastatin solubility & dissolution rate enhanced with polymer SSG in the ratio 1:7 due to increase in wetting property or possibly may be due to change in crystallinity of the drug.

scholarly journals Probabilistic risk analysis of groundwater remediation strategies

2009 ◽  
Vol 45 (6) ◽  
Author(s):  
D. Bolster ◽  
M. Barahona ◽  
M. Dentz ◽  
D. Fernandez-Garcia ◽  
X. Sanchez-Vila ◽  
...  
Keyword(s):  
Risk Analysis ◽  
Groundwater Remediation ◽  
Probabilistic Risk Analysis ◽  
Remediation Strategies ◽  
Probabilistic Risk

Crystal Chemistry and Microstructures of Uranyl Phosphates

1997 ◽  
Vol 506 ◽  
Author(s):  
Y. Suzuki ◽  
T. Murakami ◽  
T. Kogure ◽  
H. Isobe ◽  
T. Sato
Keyword(s):  
Electron Microscopy ◽  
Crystal Chemistry ◽  
Analytical Electron Microscopy ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Uranyl Phosphate ◽  
Uranyl Phosphates ◽  
Form Solid Solution

ABSTRACTThe crystal chemistry and microstructures of saleeite (Mg(UO2PO4)2•10H2O) and metatorbernite (Cu(UO2PO4)2•8H2O), from Koongarra, Australia and Shinkolobwe, Congo, were examined by X-ray diffraction analysis, infrared spectroscopy (IR), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis, transmission electron microscopy (TEM) and analytical electron microscopy. The uranyl phosphates consist of uranyl phosphate layers with cations and waters in the interlayers. The IR spectra of saleeite and metatorbernite show the presence of hydroxyls in the interlayers in addition to water molecules. The d002 spacings of the hydrated phases of saleeite and metatorbernite up to 300°C reveal that the uranyl phosphate layers themselves are quite stable in the temperature range although the interlayer water molecules are lost easily. The presence of a mixed phase of saleeite and metatorbernite is confirmed in the micrometer and nanometer scales. However, SEM and TEM examination suggest saleeite and metatorbemite generally grow separately, and rarely form solid solution or interstratification. The results imply that U is retained in uranyl phosphate minerals even when the temperature at around repositories increases, and that saleeite and metatorbernite precipitate independently from solution according to their solubilities even when Mg2+ and Cu2+ coexist in solution.

Health-Risk-Included Optimal Model for Groundwater Remediation Design under Uncertainty: A Case Study in Western Canada

2014 ◽  
Vol 955-959 ◽  
pp. 1065-1068
Author(s):  
Xing Fan ◽  
Jing Li ◽  
Jia Qi Zhang ◽  
Li He ◽  
Hong Wei Lu
Keyword(s):  
Health Risk ◽  
Groundwater Remediation ◽  
Optimal Strategies ◽  
Contaminated Site ◽  
Risk Level ◽  
Western Canada ◽  
Optimal Model ◽  
Remediation Strategies ◽  
Remediation Design

Groundwater has been polluted in different countries, and the pollutants threat to public health. In groundwater remediation design, it is necessary to take health risk level into consideration, which should be as important as the environmental standards. This study advances a health-risk-included optimal model for groundwater remediation design under relaxed environmental standard constraints. It can simulate and optimize the groundwater remediation strategies, and help the decision makers to obtain optimal strategies from various remediation alternatives. The model is applied for a petroleum contaminated site in western Canada to simulate the Pump and Treat system.

scholarly journals Solubility Enhancement of Poorly soluble Drugs by using Novel Techniques : A Comprehensive Review

2020 ◽  
Vol 13 (2) ◽  
pp. 80-93 ◽  
Author(s):  
Abikesh P.K. Mahapatra ◽  
Vinod Patil ◽  
Ravindra Patil
Keyword(s):  
Dissolution Rate ◽  
Class Ii ◽  
Systemic Circulation ◽  
Poorly Soluble Drugs ◽  
Formulation Development ◽  
Solid Dosage ◽  
Bcs Class Ii ◽  
Pharmacological Response ◽  
Poorly Soluble ◽  
Low Solubility

The primary aim of this review was to improve the solubility and Bioavailability of BCS Class-II drugs because of their low solubility and dissolution rate. Solubility is one of the imp parameter to achieve desired concentration of drug in systemic circulation for pharmacological response to be shown. Hence the class- II drugs require enhancement in solubility and dissolution rate in there formulation development particularly in solid dosage form such as in tablet and capsule. So because of this there are several methods and newer emerging technologies have been developed for increasing the solubility as well as Bioavailability of class –II drugs. In this article review on literature on newer techniques or methods as well as recent research on formulation development of class- II drugs was done.

Groundwater remediation by anionic surfactant micelles - an innovative double layer model applied to Na+ and Mg2+ association with dodecylsulfate micelles

1998 ◽  
Vol 38 (7) ◽  
pp. 99-106 ◽  
Author(s):  
Ching Yuan ◽  
Chung-Hsuang Hung ◽  
Chad T. Jafvert
Keyword(s):  
Anionic Surfactant ◽  
Groundwater Remediation ◽  
Electrical Potential ◽  
Binding Constants ◽  
High Concentration ◽  
Experimental Conditions ◽  
Counterion Binding ◽  
Double Layer Model ◽  
Poisson Boltzmann ◽  
Poisson Boltzmann Equation

The association reactions involving counterions, Na+ and Mg2+, and micelles composed of the anionic surfactant, dodecylsulfate (DS−), were investigated in ultrafiltration experiments. To access the data, an innovative model was developed that considered specific counterion binding within a Stern layer, with binding constant dependent upon the electrical potential as derived by the Poisson-Boltzmann equation and with calculation of the cmc as a function of counterion binding (or association). The experimental and model results both show that magnitude of counterion binding is greater for divalent species, Mg2+, than that for the monovalent species, Na2+. However, high concentration of Na+ compete for surface area diminishing the ability of the DS− to bind either divalent species. At experimental conditions from 0 to 100 mM NaCl addition, the binding ratio (BR) varied only from 0.58 to 0.63. The optimum binding constants, KMg and KNa, were determined to be 0.4 and 1.0 L mol−1, respectively, for the model. The experimental data and model calculated results were generally in good agreement.

Nanosuspensions: A Promising Drug Delivery Systems

2010 ◽  
Vol 2 (4) ◽  
pp. 679-684
Author(s):  
Nagaraju. P ◽  
Krishnachaithanya. K ◽  
Srinivas. V.D.N ◽  
Padma. S.V.N
Keyword(s):  
Matrix Material ◽  
Water Soluble ◽  
Log P ◽  
P Value ◽  
Science And Engineering ◽  
Water Soluble Drug ◽  
Poorly Soluble ◽  
Critical Problems ◽  
Low Solubility ◽  
Poorly Water Soluble Drug

One of the critical problems associated with poorly soluble drugs is low bioavailability and or erratic absorption. The problem is even more complex for drugs such as itraconazole and Carbamazepine (belonging to BCS CLASS II) as they are poorly soluble in both aqueous and organic media, and for those drugs having a log P value of 2. There are number of formulation approaches to resolve the problems of low solubility and low bioavailability. But all those have some limitations and hence have limited utility in solubility enhancement. Nanotechnology can be used to resolve these problems associated with conventional approaches. Nanotechnology is defined as the science and engineering carried out in the nanoscale that is 10-9 meters. Nanosuspensions consist of the pure poorly water-soluble drug without any matrix material suspended in dispersion. A nanosuspension not only solves the problems of poor solubility and bioavailability but also alters the pharmacokinetics of drug and thus improves drug safety and efficacy

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