Ionic colloid

D. Ronis, Phys. Rev. E, 49,5438 (1994). Statistical Mechanics of Ionic Colloids Interparticle Correlations and Conformational Equilibria in Suspensions of Polymer Coated Colloids. 

Fig. 46. Silica concentration in water as a function of pH /==data of Alexander et al., 7/= our experimental data on content of ionic silica in ionic-colloidal systems with total initial SiOj concentrations (mg/1) of I = 750 2 = 1500 3 = 3(X)0.

Similar conditions can be produced when alkaline solutions saturated with silica are mixed with highly acid waters. Another genetic variant inevitably suggests acid thermal waters, in which the solubility of Si02 is a function of temperature (Khitarov, 1953), as the source of the silica. When thermal waters cool, mix with surface waters, and are partially neutralized, ionic-colloidal systems with anomalously high content of monomeric silica can arise. It is obvious that both these variants reflect specific conditions that are not typical of geochemical processes in the weathered layer. 

The extended expression enables studies of phase instability in dispersions of charged particles like ionic colloids. In the context of this review, it helps to explain electrostriction or electrowetting in a confinement maintaining equilibrium with a field-free aqueous bath. Brunet et al. discussed the use of electric field to tune mixing/demixing equilibria in a multicomponent system [64, 65]. 

Wu JZ, Bratko D, Blanch HW, Prausnitz JM (1999) Monte Carlo simulation for the potential of mean force between ionic colloids in solutions of asymmetric salts. J Chem Phys lll(15) 7084-7094... 

Leunissen ME, Christova CG, Hynninen AP, Royall CP, Campbell AI, Imhof A, Dijkstra M, Roij R, Blaadem A (2005) Ionic colloidal crystals of oppositely charged particles. Nature 437 235-240... 

Limitation on Salt Removal by Ultrafiltration. Ultrafiltration with continued addition of water is an efficient way to remove salts down to a concentration of 0.03 N even from a concentrated silica sol. At these low levels there is a tendency for the salt to remain associated with the charged surface of the colloidal particles.. This may be a hitherto unrecognized phenomenon, at least in the chemistry of colloidal silica, but it must have been noted during removal of salt from other ionic colloids. It is suggested that in dilute sols where fhe charged particles are far apart and there is a high concentration of sodium counterions around the particles, there is a tendency for sulfate ions to be concentrated as a secondary layer outside of the layer of sodium ions. As shown in Figure 4.5, around each silica particle... 

Mercury has been found in seawater in a variety of operationally characterized particulate (> 0.4 or > 0.45 jum) and dissolved ( ionic , colloidal , gaseous , reactive , easily reducible , labile , organically associated , non-reactive ) forms. In addition, chemically defined species have been determined, such as elemental (H, monomethyl- (MMHg) and dimethylmercury (DMHg) Bloom et aL, 1995 Coquery and Cossa, 1995 Iverfeldt, 1988 Leermakers et al, 1995 Mason et aL, 1995). The relationship between the different species of Hg and its total concentration (Hgx) is highly variable in space (with sea area and water depth) and time (daily and seasonal changes). The procedure described here applies to the determination of total mercury . A brief outline, however, is also given on the determination of some of the major species for which more or less standardized methods are in common use. 

Yamanaka, J., Yoshida, H., Koga, T., Ise, N., and Hashimoto, T. (1999). Reentrant order-disorder transition in ionic colloidal dispersions by varying particle charge density. Langmuir 15, 4198-4202. 

Key words Order-disorder transition -crystallization - ionic colloid - silica - dispersion - ultra-small-angle X-ray... 

Order (crystal structure)-disorder (liquid structure) transition in ionic colloidal dispersions has been intensively studied [1]. Since the driving force of the ordering is electrostatic, the order-disorder transition point for the colloidal system is largely determined by the surface charge density of the particle and the salt concentration of the dispersion, Cg, in addition to the volume fraction of the particles, . A number of experimental studies have so far been made to determine the transition point as a function of Cs and 0. However, little attention has been paid on the influence of the surface charge density. This seems to be... 

A short side chain at C17 enhances the solubilization of steroids, especially when it contains a free hydroxyl group. A greater number of non-ionic molecules are required to solubilize one steroid molecule than is required by ionic micelles. In the oestrogens this difference is small, but in most of the other cases the difference is nearly 10-fold (see Table 6.16). This would indicate a different mechanism of solubilization the shift of the absorption maximum and the depression of the molar extinction for all the steroids except the oestrogens are much more pronounced in Tween solutions than in ionic colloid solutions. This would suggest a unique mode of solubilization for the oestrogens, most of which are indeed poorly solubilized, only the 21-acetoxy steroid occupying an intermediate position. 

Proteins are the most abundant macromolecules in living cells. Sixty-five percent of the protein mass of the human body is intracellular. The structure of low-nanometer-sized proteins often are organized around metal ions (Zn, Co, Fe), and possess a molecular weight of himdreds of kD. In the dry state some proteins lose their ionic nature and may become electronic conductors. When in the bodily fluid, proteins form aqueous ionic colloidal suspensions. Proteins typically carry a small positive or negative charge (dipole moment is 15-50 Debye units), and their presence increases measured sample permittivity (e) compared to that of pure supporting media (e ) by 20-200 units of permittivity. The increase is proportional (8) to the concentration of proteins C as e = + 5C. Proteins readily interact to form complexes with other molecules... 

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