Stability of ferric oxide hydrosols

Ferrihydrite gels derived in the Fe(NO3)3·9H2O–C2H5OH–CH3CHCH2O ternary system

“…In accordance with [10,20,21], the amorphous FeO(OH) gels known as ferrihydrites can re-precipitate in thirteen different phases including a-FeO(OH), bFeO(OH), c-FeO(OH), and others. For the purpose of identifying the nature of dominant chemical bonds in the Ôblack phaseÕ and Ôchocolate brown phaseÕ we have performed vibration studies of these phases by FTIR spectroscopy.…”

Formation of the active surface of Ag/SiO2 catalysts in the presence of FeO x additives

“…Once the silica gel sur face is completely covered with Fe(OH) n , the forma tion of a colloidal layer begins. Since the impregnating solution contains CF 3 COOand Ag + ions in addition to ferric nitrate, the iron hydroxide sol coagulates much more rapidly (the effect of an extraneous elec trolyte in the solution, leading to compression of the electrical double layer [12]) and the size of the result ing sol particles diminishes. Ag + cations can also be adsorbed on the surfaces of hydrosol nanoparticles, hindering first of all the further growth of the sol parti cles, and second the formation of particles of a metal lic Ag phase during heat treatment of the sample.…”

Parsons–Zobel plots: An independent way to determine surface complexation parameters?

“…Sometimes, and particularly in the case of temperature studies, rather strong electrolyte binding constants are required [23] to fit experimental data. Consequently, in its original version the Parsons-Zobel plot will not be a realistic option to estimate capacitance values for the basic Stern model in general, particularly since it is known that electrolyte binding is related to the nature of the electrolyte and that of the surface [24][25][26][27]. Structure-breaking and -making properties of the electrolyte ions and the surface with respect to the water molecules will affect both the interlayer capacitance (via distance and dielectric constant) and potentially even the electrochemical surface area.…”

“…Attempts have recently been made to incorporate water structure into surface complexation models [28]. These attempts currently do not include the more elaborate, but qualitative explanations by Dumont et al [24][25][26][27].…”