Water Clusterization in the Interparticle Space of Hydrophobic Nanosilica АМ-1

The processes occurring in hydrated powders and concentrated suspensions of hydrophobic silica were studied by 1H NMR spectroscopy. It is shown that a mixture of methyl silica and water with a hydration of less than 1 g / g is a wet powder, where water is in the form of submicron clusters filling the interparticle voids of nanosilica, and the interfacial energy is directly proportional to the amount of added water. It was found that at high water concentrations there is a spontaneous increase in the size of water structures, which is accompanied by a sharp decrease in interfacial energy, that may reflect the disappearance of narrow interparticle voids or their filling with air. It is shown that aqueous suspensions of AM-1 are easily mixed with a weakly polar organic solvent chloroform, forming a stable suspension with close the amounts both of water and chloroform. It was revealed that the aqueous suspension of methyl silica has high thixotropic properties, which depend on the time and the magnitude of the applied mechanical loads.

Selectivity switch by phase switch - The key to a high-yield furfural process

We show the effective conversion of xylose into furfural, with selectivities >90 mol%, in an aqueous-organic three-solvent system, composed of an apolar aromatic solvent, a polar organic solvent and acidic...

Dimethylchlorosilanaerosyl Impregnated With A Acetone Or Ethanol - A Multifunctional Sorbent For The Separation Of Microquantities Of Al (III), Ga (III), In (III)

A multifunctional sorbent for the separation of microquantities of elements-analogues of the aluminum subgroup was obtained by impregnation of the dimethylchlorosilanaerosyl (DMCSA) surface with a polar organic solvent (POS). The surface identification of the organized DMCSA - POS system was performed via diffuse reflection spectroscopy. The results of the study of Al (III), Ga (III), In (III) sorption using an organized system DMCSA - POS depending on the medium acidity and the nature of POS (ethanol or acetone) showed that the quantitative and selective removal of the studied elements corresponds to the formation of the neutral hydroxoforms and is due to kinetic and thermodynamic differences in the ability of Al (III), Ga (III), In (III) to hydrolysis. A participation in adsorption-extraction processes hydrophobically attached to the methyl groups of DMCSA layer POS also takes place. A method of stepwise separation of Al (III), Ga (III), In (III) from their three- and multicomponent mixtures is proposed. At the same initial concentrations of elements, the values of the separation coefficients of pairs Ga (III) - In (III) ≈ 1450 and In (III) - Al (III) ≈ 450 were calculated.