Diamine Immobilization on Silica Gel through the Sol−Gel Process and Increase in the Organic Chain by Using Glutaraldehyde followed by Ethylenediamine

Abstract

The propylethylenediamine moiety was anchored on silica in acid medium by using sol−gel methodology. A sequence of reactions was carried out with glutaraldehyde followed by ethylenediamine in order to increase the organic chain pendant groups covalently bonded to the inorganic support. All synthesized silicas were characterized by carbon and nitrogen elemental analyses, thermogravimetry, differential scanning calorimetry, solid state 13C and 29Si NMR, and calorimetry. These analyses and techniques quantitatively confirmed all reaction steps. The results found strongly indicated that some silanol groups are converted to siloxane, which presented a great stability toward ring opening in aqueous medium.

Silylating Agents Grafted onto Silica Derived from Leached Chrysotile

“…These processes corresponded to the lost of water, the condensation of the remaining silanol groups, and the organic decomposition in the modified silicas (20,21). From these results, it is observed that the thermal ana lyses show that the bonded phases become less stable as longer alkyl group chains are bonded to the inorganic backbone.…”

“…These large values, obtained by using the present procedure, are in agreement with the great potentiality of this new matrix to react with silylating agents. To support this argument, a normal chromatographic silica gel has a maximum amount of anchored molecules on the order of 1.5 mmol g −1 , when this same experimental method was employed (21). On the other hand, within the series of organofunctionalization of these matrices at different timers, the organic content remains constant after 48 h of reaction.…”

New Factorial Designs to Evaluate Chemisorption of Divalent Metals on Aminated Silicas

“…The synthesis of both silicas follow the procedure described elsewhere (26), but with some modifications. About 50 g of activated silica was immersed in 100 mL of dry xylene and 20 mL of tmpe was added.…”

A relevante potencialidade dos centros básicos nitrogenados disponíveis em polímeros inorgânicos e biopolímeros na remoção catiônica

“…A potencialidade em aumentar a cadeia do agente sililante pode ser constatada através de um dialdeído, cuja reação controlada em termos estequiométricos, superfície aminada: glutaraldeído, forma facilmente a base de Schiff, a qual pode ser reduzida em etapas posteriores, para seguir uma seqüência de reações para conduzir ao produto final com claro crescimento da cadeia 15 , como mostra a Equação 8. Após a imobilização e redução da dupla ligação, o material possui a capacidade de remover cátions 16 .…”