Toxicity of boehmite nanoparticles: impact of the ultrafine fraction and of the agglomerates size on cytotoxicity and pro-inflammatory response

International audienceBoehmite (γ-AlOOH) nanoparticles (NPs) are used in a wide range of industrial applications. However, little is known about their potential toxicity. This study aimed at a better understanding of the relationship between the physico-chemical properties of these NPs and their in vitro biological activity. After an extensive physico-chemical characterization, the cytotoxicity, pro-inflammatory response and oxidative stress induced by a bulk industrial powder and its ultrafine fraction were assessed using RAW264.7 macrophages. Although the bulk powder did not trigger a significant biological activity, pro-inflammatory response was highly enhanced with the ultrafine fraction. This observation was confirmed with boehmite NPs synthesized at the laboratory scale, with well-defined and tightly controlled physico-chemical features: toxicity was increased when NPs were dispersed. In conclusion, the agglomerates size of boehmite NPs has a major impact on their toxicity, highlighting the need to study not only raw industrial powders containing NPs but also the ultrafine fractions representative of respirable particles. Read More: http://informahealthcare.com/doi/abs/10.3109/08958378.2014.92599

Silica Nanoparticles for the Stabilization of W/O Emulsions at HTHP Conditions for Unconventional Reserves Drilling Operations

A novel generation of drilling fluids based on the principle of Pickering emulsions was prepared in this work using three different types of commercial silica nanoparticles with various hydrophobicity and particle sizes. We demonstrated that a threshold of nanoparticles concentration was necessary to stabilize the emulsions which strongly depended upon the particles wettability (hydrophobicity) and sizes. Nonetheless, on increasing the water phase volume fraction, a catastrophic inversion from Water-in-Oil (W/O) to Oil-in-Water (O/W) was obtained for emulsions prepared using amphiphilic silica nanoparticles. Particles wettability has proven to be strongly affected by the pH of the aqueous phase. However, changing the salinity of the brine phase did not have remarkable effects neither on the stability to coalescence/sedimentation nor on the droplet size distribution of the emulsions prepared. Oscillatory rheology illustrates that addition of clay particles boosts fluids thixotropic properties which experienced full recovery of gel strength even after aging. The drilling fluids prepared were aged for 16 h at 350 °F (177 °C) and 500 psi (35 bar) and provided high stability contrary to surfactant stabilized Oil-Based-Mud (OBM) that failed completely after aging

Impact of three different TiO2 morphologies on hydrogen evolution by methanol assisted water splitting: Nanoparticles, nanotubes and aerogels

International audienceIncreasing the activity of a photocatalyst goes through the improvement of both its absorption (light) and adsorption (reactant) properties. For a given semiconducting material, the charge carrier separation is also a very important step. Properly combining chosen phases is one option to improve this separation (example of the commercial P25) and depositing platinum on the surface of the catalyst, another one. In some cases, coupling both may nevertheless lead to a decrease of photoactivity or at least limit the potentiality of the catalyst. A third option, consisting in modifying the morphology of the photoactive phase, has shown very promising results. In this study, we have elaborated, characterized and evaluated the hydrogen evolution potentiality (through methanol assisted water splitting) of different TiO2 morphologies: nanoparticles, nanotubes and aerogels. These materials have shown different behaviours depending on both their composition and morphology. Different types of separation processes have been claimed to account for the observed different photoactivities, with more or less pronounced synergetic effects, due to: the use of Pt as a co-catalyst, the mixture of different TiO2 phases (anatase and TiO2(B) or rutile) and the specific morphology of the samples (nanotubes or aerogels). Among all the tested samples, the TiO2 aerogel supported Pt one exhibited very promising performances, three times as active as P25 supported Pt, which is already much more active than pure P25 in our testing conditions

Effets du dodécylsulfate sur la précipitation d'hydroxydes de nickel

ST ETIENNE-ENS des Mines (422182304) / SudocSudocFranceF

Different strategies to obtain Y doped barium cerium oxide particles

ISBN : 978-954-92483-1-9International audienc

Synthèse de nanoparticules photocatalytiques activables par rayons X pour la mise au point d'une nouvelle thérapie anti-cancéreuse par voie physique

PARIS-MINES ParisTech (751062310) / SudocSudocFranceF

Precipitation of nickel hydroxides from nickel dodecylsulphate.

6 pages Comptes-rendus du colloque EMRS Fall meeting, Varsovie september 6th - 7th 200

Surfactant effects on pH-controlled synthesis of nickel hydroxides

International audienceThe aim of the present work is to determine at 60 °C, the influence of the specific nature of nickel salt and pH on nickel hydroxide features such as crystallographic structure and morphology. Within the range 8 ≤ pH ≤ 11.5, a home-made nickel functionalized surfactant, nickel di-dodecylsulfate Ni(C12H25SO4)2 is compared to usual salts (nickel nitrate Ni(NO3)2 and nickel sulfate NiSO4). In both cases, a sharp transition appears for pH about 10. In the classic salt case, the transition mainly affects morphology, that could be evidenced by the crosschecking of complementary techniques as SEM and nitrogen gas adsorption. For pH < 10, β-Ni(OH)2 platelets are yielded, whereas more basic conditions lead to randomly aggregated nano-grains of badly crystallized β hydroxide. Inversely, by employing the functionalized surfactant, 2D morphology is maintained in the whole pH-range, but the crystal structure is pH-controlled (α phase with interlamellar dodecylsulfate for pH ≤ 9.5, and β phase for pH ≥ 10.5)