Silica aqueous, thermodynamic properties

Walther J. V. and Helgeson H. C. (1977). Calculation of the thermodynamic properties of aqueous silica and the solubility of quartz and its polymorphs at high pressures and temperatures. Amer. Jour. Set, 277 1315-1351. 

Fig. 3 Energy diagram of strongly doped n-Si/Si02 electrode in contact with aqueous electrolyte solution. The diagram contains the formal redox potentials of the primary radicals and combined redox and luminescence properties of Ru(bpy)3, and 2,6-bisPM,N-bis(carboxymethyl)amino-methyl]-4-benzoylphenol (ligand L). The diagram demonstrates clearly that on thermodynamical basis, both of these luminopbores could be excited even to their singlet excited states in the simultaneous presence of hydrated electrons and sulfate radicals via both ox-red and red-ox pathways. However, in practice the ox-red pathway seems to be dominant in both cases. E-type electron centers in silica fully correspond to F and F electron centers in alumina [36]...

Already reported CAV/0 microemulsion technique was used to prepare the MLPs [12-15]. Briefly, this technique consists of an oil phase, a colloidal water phase, and surfactants and possesses specific physicochemical properties such as transparency, isotropy, and thermodynamic stability, n-Heptane was used as the oil phase, BrijSO as surfactant and tetraethoxysilane (TEOS) as silica precursor. This method is based on the hydrolysis and the condensation of TEOS. There is a major importance to the concentration and the order of addition of the different species. To the mixture of heptane/BrijSO we add slowly a colloidal suspension of y-Fe203 MPS in water (13 mg in 750 pL of water). After 15 min of stirring we added the cluster units in a mixture of Et0H H20 (1 1). Afterward we introduce an aqueous ammonia solution (28%). Finally the TEOS was added and the microemulsion was stirred during 3 days before several precipitation/resuspension to transfer our MLPs in water. 

Upon surface-thermodynamic analysis of protein adsorption onto hydrophilic surfaces such as silica or glass, based on the known surface properties of the hydrophilic protein as well as of the hydrophihc mineral substratum, one would arrive at the conclusion that the macroscopic-scale interactions in a neutral aqueous medium are so strongly repulsive that adsorption should not occur, cf. van Oss et al. (1995a). In spite of this prediction, protein adsorption onto hydrophilic glass, silica, etc. does take place, at neutral pH (MacRitchie, 1972 van Oss et al., 1995b). The mechanism of protein adsorption onto hydrophilic surfaces is quite different from that operative with... 

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