Jérôme Frayret

Investigation of uranium-colloid interactions in soil by dual field-flow fractionation/capillary electrophoresis hyphenated with inductively coupled plasma-mass spectrometry.

This paper deals with the study of uranium-colloid interactions in a carbonated soil. The work is focused on the immediately available fraction obtained after a leaching process, according to a normalized batch method. In order to characterize the different colloidal carriers, Asymmetrical Flow Field-Flow Fractionation (As-Fl-FFF) coupled to different detectors (UV, Multi Angle Laser Light Scattering (MALLS) and Inductively coupled Plasma-Mass Spectrometry (ICP-MS)) was used. The colloidal carriers are mainly inorganic particles (carbonated particles and clays) mixed with organic substances. Furthermore, dissolved and colloidal uranium species in the leaching solutions were monitored by Capillary Electrophoresis (CE) coupled to ICP-MS, in order to investigate the uranium/colloids interactions. According to the first results, uranium fate in this specific soil is controlled by sorption/desorption phenomena, strongly pH dependent.

Mechanism for the oxidation of phenol by sulfatoferrate(VI): Comparison with various oxidants

The oxidative action of a solid and stable potassium sulfatoferrate(VI) material on phenol was studied in aqueous solution under different stoichiometries. The performance towards phenol and the total organic carbon is compared to that of potassium permanganate and calcium hypochlorite. The total mineralization of phenol is not completely achieved by the studied chemical oxidants, and some oxidation products have been identified by gas chromatography-mass spectrometry and gas chromatography-flame ionization detector analysis. A radical reaction pathway, involving the formation of oxidation intermediates or by-products such as benzoquinone, phenoxyphenol and ring opening products, is proposed for the decomposition of phenol by ferrate(VI). Phenoxyphenol is also involved in the oxidation mechanism for permanganate whereas chlorinated phenols are produced by hypochlorite. The role of the chloride anion impurity of the potassium sulfatoferrate(VI) material has been highlighted in this study; no negative impact on the removal of phenol and its mineralization is observed compared to the use of a pure commercial ferrate(VI). The efficiency of sulfatoferrate(VI) for the oxidative removal of phenol from industrial wastewater is also confirmed.

Determination of the correlation between physical measurements of roughness, optical properties, and perception of frosted glass surfaces.

Chemical frosting is used as a surface decorating method by many glass package producers. After immersion in an acid frosting bath, glass items present the desired frosted effect. The perception of this particular effect is due to the formation of a microscopic crystalline pattern on the glass surface, which scatters light passing through the glass surface. The chemical composition of the frosting bath influences these properties by modifying the surface roughness, the depth, and the average slopes of the crystalline pattern. Perception of the final aspect can be modified according to the chemical composition of the frosting bath. Different correlations between all these parameters exist and have been quantified.

Corrosion Protection of Magnesium Alloys: From Chromium VI Process to Alternative Coatings Technologies

Magnesium and its alloys present several advantages such as a high strength/weight ratio and a low density. These properties allow them to be used for many aeronautical applications but they are very sensitive to corrosion. In order to solve this problem, chromium VI conversion coatings (CCC) are deposited on the surface before a protective top coat application. This process is now limited by several environmental laws due to the high toxicity of hexavalent chromium. However the chemical mechanisms of CCC deposition will be detailed in this chapter in order to understand the chemical properties of this coating. Pre-treatment steps allow cleaning and preparing the surface for improving the coating deposition. A final layer of chromium (III) oxide and magnesium hydroxide composes the coating allowing the protective properties. Orthorhombic potassium chromate clusters trapped on the coating surface give self-healing property to the coating. Alternative conversion coatings are based onto solutions containing chromium (III), permanganate, phosphates, Rare Earth Elements (REEs) or vanadium. The second part of this chapter will detail the deposition and the protection mechanisms of these promising processes of CrVI substitution. Among them, permanganate/phosphate-based coating presents a better corrosion resistance than CCC and REEs have very efficient self-healing properties.

Removal of pharmaceuticals by a potassium ferrate(VI) material: from practical implementation to reactivity prediction

This study investigated the degradation of metoprolol (MET), carbamazepine (CBZ), ciprofloxacin (CIP) and hydroxy-ibuprofen (OH-IBU) in aqueous solution by a ferrate(VI) material obtained by dry synthesis according to patent WO2008065279. Ferrate(VI) had the highest reactivity with CIP, with a second-order rate constant of 89 ± 2 M−1 s−1 at pH 10.3 ± 0.3. The rate constants of ferrate(VI) with MET and CBZ under the same conditions were 3.7 ± 0.3 M−1 s−1 and 13.1 ± 0.8 M−1 s−1, respectively, while no reaction took place with OH-IBU. We also evaluated the removal efficiencies of nine selected pharmaceuticals, including MET, CBZ, CIP and OH-IBU, detected in a real hospital wastewater (HWW) with concentrations ranging from 73 ± 4 ng L−1 to 159 ± 8 μg L−1 by applying Fe(VI) technology. The abatement of the targeted pharmaceuticals depends on their structures. Because Fe(VI) captures electrons during the oxidation process, we proposed to correlate the reactivity of Fe(VI) with the first ionization potential (IP) of the pharmaceuticals. The first IP values of MET, CBZ, CIP, OH-IBU and diclofenac (DFC) were determined by gas-phase UV photoelectron spectroscopy (UV-PES). The UV-PES data were also interpreted using density functional theory (DFT) calculations.