Fire retardant behaviour of halogen-free calcium-based hydrated minerals

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Experimental study of mercury removal from exhaust gases

An initial study has been made of the use of synthetic zeolites for mercury capture from exhaust gases. Synthetic zeolites (Na-X and Na-P1), and for comparison a natural zeolite (clinoptilolite) and activated carbon with bromine (AC/Br) were tested for mercury uptake from a gaseous stream. The materials were subjected to mercury adsorption tests and their thermal stability was evaluated. The untreated synthetic zeolites had negligible mercury uptake, but after impregnation with silver, the adsorption of mercury was markedly improved. The synthetic zeolite Na-X impregnated with silver adsorbed significantly more mercury before breakthrough than the activated carbon impregnated with bromine, indicating the potential of zeolite derived from coal fly ash as a new sorbent for capture of mercury from flue gases

Nouveaux additifs calco-magnésiens pour améliorer la tenue au feu des polymères

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IM-17: a new zeolitic material, synthesis and structure elucidation from electron diffraction ADT data and Rietveld analysis

International audienceThe synthesis and the structure of IM-17, a new germanosilicate with a novel zeolitic topology, prepared hydrothermally with decamethonium as the organic structure directing agent, are reported. The structure of calcined and partially rehydrated IM-17 of chemical formula per unit cell |(H2O)14.4|[Si136.50Ge39.50O352] was solved ab initio using electron diffraction ADT data in the acentric Amm2 (setting Cm2m) space group and refined by the Rietveld method. This new zeolite framework type contains a 3D pore system made of intersecting 12, 10 and 8-ring channels

Thermal conductivity of ceramic/metal composites from preforms produced by freeze casting

International audiencePorous alumina and zirconia preforms, processed by ice templating, have been used to manufacture ceramic/metal composites by aluminium alloy infiltration. The aim of the present work is to study the influence of the ceramic material nature and of the initial porous structure on the thermal conductivity anisotropy of the composite in order to assess potential applications in the field of thermal management. The materials are characterised in terms of pore volume fraction and pore size before and after metal infiltration. The freeze casted preforms exhibit anisotropic lamellar structures with ellipsoidal pores ranging from 35 µm to 40 µm and porosity fractions from 64 to 67%. After metal infiltration, composite parts present the same anisotropic morphology, which correspond to alternating ceramic and metal layers. Thermal conductivities have been determined, with an average of 80 W m−1 K−1 and 13 W m−1 K−1 parallel and perpendicular to the freezing direction respectively, for zirconia/metal composites. Theoretical values of thermal conductivity can be calculated using the Maxwell-Eucken relation, to handle the residual porosity, in combination with series and parallel resistance models to describe the overall anisotropic character. These give good agreement to experiment

Microwave sintering: Improvement of the electrical properties of barium titanite doped with calcium and zirconia

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Water-Based Synthesis of Zr₆‑Based Metal–Organic Framework Nanocrystals with Sulfonate Functions: Structural Features and Application to Fructose Dehydration

A series of zirconium-based metal–organic framework (MOF) nanocrystals (95–211 nm) displaying sulfonate functions (UiO-66-SO3H) was prepared in N,N-dimethylformamide (DMF)the conventional solventand water, and their physicochemical properties were thoroughly investigated. In particular, X-ray diffraction results suggest that upon replacing DMF with water, the resulting MOF crystal structure presents a highly defective structure belonging to the space group Im3̅ instead of typical Fm3̅m. The acid catalysts were applied to the fructose dehydration into 5-hydroxymethylfurfural (5-HMF). Complete conversion of fructose over UiO-66-SO3H prepared in water was reached after only 30 min at 100 °C, in line with its stronger Brønsted acidity. In comparison, its counterpart prepared in DMF showed only 30% fructose conversion. Moreover, the intrinsic catalytic effect at 80 °C was only observed with the water-based UiO-66-SO3H. Without reactivation of the catalyst, recycling tests demonstrated the preservation of its structural integrity upon nine consecutive cycles, while a gradual loss of the catalyst activity was attributed to the humin adsorption on the MOFs

Combined Modeling and Biophysical Characterisation of CO2 Interaction with Class II Hydrophobins: New Insight into the Mechanism Underpinning Primary Gushing

Although there is a common agreement that hydrophobins and CO2 are responsible for primary gushing of carbonated beverages, the bio-molecular mechanism of this phenomenon is not well understood. Here, hydrophobin HFBII has been produced, extracted, and purified. A gushing test and DLS analysis was performed and allowed the authors to design an MD simulation setup to investigate the interaction of CO2 molecules with HFBII in time. The results indicate that CO2 molecules tend to aggregate at the hydrophobic patch of HFBII twice as much as to the rest of the protein. A model is proposed that elucidates the "nanobomb" formation depicting a definite chemical and biophysical description of the primary gushing mechanism. © 2012 American Society of Brewing Chemists, Inc.status: publishe