Synthesis of MCM-41 nanomaterial from Algerian bentonite: influence of synthesis pH

Mesoporous materials of the MCM-41 type were synthesized from Algerian bentonite as an aluminosilicate source without the addition of pure silica and aluminum reagents. The samples were synthesized under hydrothermal condition using cetyltrimithylammonium bromide (CTAB) as surfactant. The influence of initial synthesis pH on the material properties of as-synthesis MCM-41 samples was studied at different temperatures of crystallization. The samples were characterized using several techniques e.g. X-ray diffraction (XRD), N2 adsorption-desorption and transmission electron microscope (TEM). The experimental results showed that bentonite can be used as an aluminosilicate source for the synthesis of Al-MCM-41. By decreasing the synthesis temperature of crystallization, it is necessary to decrease the synthesis pH value to form the best ordered hexagonal phase and eliminate the lamellar phase.Keywords: bentonite; alkaline fusion; pH; Al-MCM-4

THERMOGRAVIMETRIC ANALYSIS OF A TALC MIXTURE

A commercial talc also containing chlorite. dolomite and magnesite was subjected to thermogravimetric analysis to determine its mineral composition. Knowledge of the reactions and the decomposition temperatures, as well as the crystallochemical formulae of the phases present, has permitted the application of a system of equations that has provided mineral composition results in good agreement with standard analysis obtained via elemental chemical analysis

Addition d'alkyl-cuivres sur divers dérivés propargyliques

The stereoselective syn addition of alkylcopper reagents to various propargylic alcohols, ethers, bromides and acetates has been studied. At low temperatures, propargylic ethers give rise to alcoxyvinylcopper derivatives which have been characterised

Organo-vinyl-copper compounds V. Regioselectivity in the addition of alkyl-copper-magnesium bromide reagents on various propargyl derivatives

The syn addition of alkylcopper reagents to various propargyl derivatives, i.e. HCtriple bond; length as m-dashC---C---Z (Z=X, OAc, NR2, SEt, OR, O-), has been studied. Among the various factors governing the regioselectivity, the nature of the heteroatom in the group Z and the polarity of the solvent are particularly important. The vinylcopper derivatives obtained from propargyl ethers have been carboxylated, iodinated and oxidised

Understanding water transport through polysulfone asymmetric membranes

International audienc

Understanding water transport through polysulfone asymmetric membranes

International audienc