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Pure-silica and iron-containing mesoporous materials are obtained by different synthesis procedures in the presence of cetyltrimethylammonium cation at neutral or slightly acidic pH. Several salts or hydrochloric acid are used as condensing agents. The property of the samples are characterized as a function of the washing procedure. Washing by water alone does not extract the template and does not affect the stability of the solid. Washing by ethanolic solution is an effective way to extract the template, and severely affect the stability and the porosity of the samples.

Novel hybrid mesoporous and functionalized materials with controllable surface area and pore dimensions with functional basic sites (-NH2) were synthesized from magadiite and [Al]-magadiite as layered silicate precursors. The variable pore structure and properties of these materials were investigated in these solids by using different CTA(+)/Na(+) (CTA(+) = cetyltrimethylammonium cation) molar ratios in the pre-modification step with aminopropyltriethoxysilane (APTS) and tetraethoxysilane (TEOS). Characterizations were carried out by different techniques to probe the effects of the amounts of interlayer surfactant in the synthesis of the pillared and/or grafted materials. The crystalline structures of magadiite and [Al]-magadiite layers were maintained as evidenced by FT-IR and SAED and contain pillars and aminopropyl groups in the interlayer space. The hybrid solids were compared to the pillared forms (H. M. Moura, F. A. Bonk and H. O. Pastore, Eur. J. Mineral., 2012, 24, 903) and to the aminopropyl-grafted forms and presented the properties of both solids with the CO2 adsorption capability improved considerably.

The reactions of four dyes of the alizarin green series with UO22+ ions in the presence of cetyltrimethylammonium cation (CTA+, S) were studied. At lower tenside concentration than the critical micelle concentration (cmc), defined ternary UO2L2S4 or UO2L2S2 complexes are formed in the solution. The stability constants of the complexes formed were determined and a procedure for the photometric determination of uranium and cetyltrimethylammonium was proposed.

A novel method for the determination of timolol in pharmaceutical products has been developed and is described. The method employs high-performance liquid chromatography (HPLC) on silica dynamically modified with the cetyltrimethylammonium cation to quantitate the analyte. The use of this type of reversed-phase HPLC system for timolol determinations results in improved quality of chromatography, especially in terms of peak tailing and peak efficiency, in comparison to chromatography on bonded-phase silica. Column-to-column as well as manufacturer-to-manufacturer reproducibility for this separation on silica columns has been obtained and is better in our hands than that encountered with bonded-phase column packings. The method has been shown to be linear for the compounds studied, comparably accurate and precise to bonded-phase methods and specific for timolol in a variety of pharmaceutical formulations. Under the conditions specified, timolol can be successfully separated from its three known potential degradates. Possible explanations of the primary retention mechanisms for the analytes are offered.

We report here on the interaction between silica surfaces in a range of CTA+ (cetyltrimethylammonium cation) concentrations up to the point of zero charge (5 × 10-5 M) in a background electrolyte (...