We present a neutron scattering analysis of the density and the static structure factor of confined methanol at various temperatures. Confinement is performed in the cylindrical pores of MCM-41 silicates with pore diameters D=24 Å and D=35 Å. A change of the thermal expansivity of confined methanol at low temperature is the signature of a glass transition, which occurs at higher temperature for the smallest pore. This is an evidence of a surface induced slowing down of the dynamics of the fluid. The structure factor presents a systematic evolution with the pore diameter, which has been analyzed in terms of excluded volume effects and fluid-matrix cross-correlation. Conversely to the case of Van der Waals fluids, it shows that stronger fluid-matrix correlations must be invoked most probably in relation with the H-bonding character of both methanol and silicate surface. 2/33
International audienceThe aim of the present work was to evaluate the morphologic and chemical characteristics of Isabel grape (Vitis labrusca x Vitis vinifera) bagasse and to describe the adsorption of diclofenac sodium (DCF) from aqueous solutions by this biomass. Grape bagasse was constituted mainly of particles with heterogeneous shapes and sizes, and it exhibited a macroporous structure and a low specific surface area (∼ 2 m2 g-1). The adsorbent material was also rich in oxygenated functional groups, especially -OH, and required an acidic pH to neutralize its surface. With respect to the adsorption of DCF, the percentage removal did not appear to depend on the initial concentration of the pharmaceutical. A pseudo-second-order kinetic model described the rate-controlling step, and the adsorption isotherms were well fitted by the Freundlich model. Concerning the thermodynamic data, the results showed that the adsorption of DCF onto grape bagasse occurred via an exothermic process accompanied by a decrease in the randomness at the solid/solution interface. Furthermore, the removal percentages of DCF ranged from 16.4 to 22.8%
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