Center Grup Of Tecniques Of Separacio En Quimica

Barcelona, Spain

Center Grup Of Tecniques Of Separacio En Quimica

Barcelona, Spain
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Candela A.M.,Center Grup Of Tecniques Of Separacio En Quimica | Coello J.,Grup de Quimiometria Aplicada | Palet C.,Center Grup Of Tecniques Of Separacio En Quimica
Separation and Purification Technology | Year: 2013

The objective of this study was the development and optimization of a method for the liquid-liquid extraction and recovery of Uranium (VI) traces (0.10 mg/L). A comparison was made of three different extracting agents at 0.10 mol/L: tri-n-butyl phosphate, methyltrioctylammonium chloride, and bis(2-ethylhexyl) phosphoric acid. As the optimized chemical conditions of the liquid-liquid systems are very important for the future applications for the extraction, recovery and pre-concentration of Uranium (VI) traces, whether in bulk liquid membranes or in supported liquid membranes systems, a response surface methodology was adopted. A Doehlert design is used to obtain a quadratic function relationship between the percentage of recovery of uranyl ion and the amount of bis(2-ethylhexyl) phosphoric acid in kerosene, as extracting agent (0.001-0.050 mol/L) and that of phosphoric (0.192-0.718 mol/L) and citric (0.206-0.698 mol/L) acids, mixed as recovery agents. From the results, the most important effects on the recovery are the concentration of bis(2-ethylhexyl) phosphoric acid in the organic phase and the concentration of phosphoric acid in the stripping solution, while the concentration of citric acid only favors the extraction of Uranium (VI) when the other compounds are at opposite levels of concentration. From the mathematical model, optimal conditions for the back-extraction of Uranium (VI) were found with predicted recoveries of 99%, which were later corroborated experimentally. © 2013 Elsevier B.V. All rights reserved.


Candela A.M.,Center Grup Of Tecniques Of Separacio En Quimica | Benatti V.,University of Pavia | Palet C.,Center Grup Of Tecniques Of Separacio En Quimica
Separation and Purification Technology | Year: 2013

The present study describes the pre-concentration of Uranium (VI) from nitric acid solutions (0.100 mg/L) by using bulk liquid membrane (BLM) and supported liquid membrane (SLM) systems. The transport of Uranium (VI) through both membrane systems was studied using low concentration of bis(2-ethyl hexyl) phosphoric acid (D2EHPA) as carrier in kerosene solvent which favors the removal of Uranium (VI) traces (0.001 or 0.004 mol/L). The stripping used was a mixture of phosphoric acid and citric acid, with concentrations ranging from 0.150 mol/L up to around 0.600 mol/L, which improves the removal of the Uranium (VI). In the case of SLM, the polymeric supports used were homemade Polysulfone membranes (PSf) and commercial Polyvinylidene Fluoride membranes from Millipore (PVDF). The kinetics of the uranyl ion transport system was studied for up to 24 h under fixed physical and chemical conditions. Maximum extraction values obtained were above 95%, and recovery yields were in the range 57-79% for the BLM and 90% for the SLM. Pre-concentration systems in both kinds of membrane systems are properly demonstrated and presented in this paper. © 2013 Elsevier Inc.

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