Reactivity of silanol groups on zeolite surfaces

Electrochemical behavior of hydrophobic silane–zeolite coatings for corrosion protection of aluminum substrate

“…35,36 Indeed, the zeolite crystals are characterized by the presence of external silanol functional groups, SiOH, that can interact with the silane matrix, 37,38 modifying the surface behavior of silico-aluminates. 27 Potentiodynamic test Figure 4 displays cathodic potentiodynamic polarization curves in a naturally aerated NaCl 3.5% solution for bare aluminum and for composite silane coatings at varying zeolite content.…”

“…On the basis of this reactivity, various agents, as silanes, can easily have a superficial interaction. 27 Due to their crystal lattice with pores of molecular size and peculiar abilities, such as the property to selectively exchange ions and molecules according to size, shape, and/or upload, zeolites are promising candidates to be exploited in various industrial applications. 28 An equally important feature is the inherent nontoxicity of the zeolite coating; thus these could represent an interesting and environmental friendly alternative to chromium-based surface treatments.…”

Biosorption of Heavy Metals – New Perspectives

“…This improvement was met with success through different methodologies, which resulted in supports for the direct adsorption of chromate and dichromate ions or via indirect processes which first involve reduction of Cr VI . These methodologies can be separated into three categories: surfactant-modified zeolites [72][73][74][75][76][77][78], surface functionalization [79][80][81][82][83][84][85] and metal modification [86]. None of these processes requires changes promoted during synthesis or crystallization of zeolites, meaning they are applicable to natural zeolites as well.…”

Atomic-level studies of the depletion in reactive sites during clay mineral dissolution

“…To quantify chemically the number of non-hydrogen bonded Q 3 SiOH sites per gram, we bind a probe molecule, (3,3,3-trifluoropropyl) dimethylchlorosilane (TFS), to reactive hydroxyl groups and quantify the number of attached TFS molecules with 19 F solid-state nuclear magnetic resonance (NMR) spectroscopy. The TFS molecule is an ideal probe for quantifying reactive hydroxyl groups; not only do chlorosilanes selectively attach to non-hydrogen-bonded Q 3 SiOH groups (Lochmuller and Kersey, 1988;Vandervoort et al, 1990;Kawai and Tsutsumi, 1998;Zhao and Lu, 1998;Washton et al, 2008), but each TFS molecule contains three fluorine atoms, of which the fluorine-19 isotope is NMR active and 100% abundant. To quantify the number of chemisorbed TFS molecules, 19 F magic angle spinning (MAS) NMR is utilized via a comparison of integrated peak intensities of TFS-treated samples with a 19 F-containing reference having a known concentration of spins.…”