Suspension colloidal

Clusters of metal atoms can form colloidal suspensions. Colloidal clusters of copper, silver, and gold in glass are responsible for some of the vivid colors of stained glass in medieval cathedrals. Even aqueous suspensions of metal clusters are known (Fig. 8.45). 

The examples in Table 12-3 illustrate the diversity of colloidal suspensions. Colloidal suspensions are commonly found in nature, and humans have learned how to make useful suspensions. Some of these are foods such as butter, Ice cream, and whipped cream. Others are personal care items like shampoos, shaving creams, and hair sprays. 

The typical viscous behavior for many non-Newtonian fluids (e.g., polymeric fluids, flocculated suspensions, colloids, foams, gels) is illustrated by the curves labeled structural in Figs. 3-5 and 3-6. These fluids exhibit Newtonian behavior at very low and very high shear rates, with shear thinning or pseudoplastic behavior at intermediate shear rates. In some materials this can be attributed to a reversible structure or network that forms in the rest or equilibrium state. When the material is sheared, the structure breaks down, resulting in a shear-dependent (shear thinning) behavior. Some real examples of this type of behavior are shown in Fig. 3-7. These show that structural viscosity behavior is exhibited by fluids as diverse as polymer solutions, blood, latex emulsions, and mud (sediment). Equations (i.e., models) that represent this type of behavior are described below. 

Fig. 7.1 gives a size spectrum of water-borne particles. Particles with diameters less than 10 pm have been called colloids. In soils, the clay-sized and fine silt-sized particles are classified as colloids. Colloids do not dissolve, but instead remain as a solid phase in suspension. Colloids usually remain suspended because their gravitational settling is less than 10 2 cm s 1. Under simplifying conditions (spherical particles, low Reynolds numbers), Stokes law gives for the settling velocity, vs... 

Sugimoto,T. Waki, S. Itoh, H. Muramatsu, A. (1996) Preparation of monodisperse platelet type particles from a highly condensed K-FeOOH suspension. Colloids Surfaces 109 155-165. 

Leong, Y.K., Scales, P.J., Healy, T.W., Boger, D.V. (1995). Interparticle forces arising from adsorbed polyelectrolytes in colloidal suspensions. Colloids and Surfaces A Physicochemical and Engineering Aspects, 95, 43-52. 

Alba, F. Crawley, G.M. Fatkin, J. Higgs, D.M.J. Kippax, P.G., Acoustic spectroscopy as a technique for the particle sizing of high concentration colloids, emulsions and suspensions Colloids and Surfaces A Physiochem. Eng. Asp. 1999, 15, 495-502. 

A system of solid particles dispersed in a liquid. Suspensions were previously referred to as suspensoids , meaning suspension colloids. Aside from the obvious definition of a colloidal suspension, a number of operational definitions are common in industry, such as any dispersed matter that can be removed by a 0.45 pm nominal pore-size filter. 

SJ4. Characteristic property Suspension Colloidal solution True solution... 

In this chapter, we have described the colloid chemistiy of ceramic powders in suspension. Colloid stability is manipulated by electrostatic and steric means. The ramifications on processing have been discussed with emphasis on single-phase ceramic suspensions with a distribution of particle sizes and composites and their problems of component segregation due to density and particle size and shape. The next chapter will discuss the rheology of Uie ceramic suspensions and the mechanical behavior of dry ceramic powders to prepare the ground for ceramic green body formation. The rheology of ceramic suspensions depends on their colloidal properties. 

Ramakrishnan, V. and S. G. Malghan (1998). Stability of alumina-zirconia suspensions. Colloids Surfaces A Physicochem. Eng. Aspects. 133, 1-2, 135-142. 

Contaminant species Particulate matter and suspensions Colloidal impurities High-molecular-weight organics Middle-molecular-weight organics Low-molecular-weight organics Multivalent ionic solutes Acids... 

Somasundaran P, Xiang Y, Krishnakumar S. Role of conformation and orientation of surfactants and polymers in controlling flocculation and dispersion of aqueous and nonaqueous suspensions. Colloids Surf A 1998, 133, 125-133. 

See suspension colloid chemistry. (2) In the field of optics, dispersion denotes the retardation of a light ray, usually resulting in a change of direction as it passes into or out of a substance, to an extent depending on the frequency. Dispersion is a critically important property of optical glass. 

Note Wolfgang Ostwald stated, There are no sharp differences between mechanical suspensions, colloidal solutions, and molecular [true] solutions. There is a gradual and continuous transition from the first through the second to the third. ... 

For example, an alumina coating with a median pore size of typically 100 nm can be prepared from a suspension (in water) of commercially available submicron alumina powder with a mass based median diameter of 500 nm. In such a suspension colloidal interactions determine to a large extent the properties of the suspension. The particle packing properties are disturbed by the presence of a fraction of aggregates which always exist in such commercial powders. This fraction can be removed from a colloidally stable suspension by means of sedimentation fractionation (see Ref. [5] for an example). 

COLLOID GROUT A grout in which the dispersed solid particles remain in suspension (colloids). 

Wang, J. and Gao, L., Adsorption on polyethylenimine on nanosized zirconia particles in aqueous suspensions../. Colloid Interf. Sci., 216, 436, 1999. 

Ramakrishnan, V., Pradip, and Malghan, S.G., The stability of alumina-zirconia suspensions. Colloids Surf. A, 133, 135, 1998. 

Labib, M.E. and Williams, R., An experimental comparison between the aqueous pH scale and the electron donocity scale. Colloid Polym. Sci., 264, 533, 1986. Morris, G.E. et al.. Surface chemistry and rheological behaviour of titania pigment suspensions. Colloids Sutf. A, 155, 27, 1999. 

Johnson, S.B., Russell, A.S.. and Scales, P.J., Volume fraction effects in shear rheology and electroacoustic studies of concentrated alumina and kaolin suspensions. Colloids Surf. A, 141, 119. 1998. 

Biegler, C. and Houchin, M.R., Siderite (FcCO,) Its dissolution and interaction with stannic oxide in aqueous suspensions. Colloids Surf., 21, 267, 1986. 

Roncari. E. et al., Vanadium-doped TiOj catalysts. A unifying picture of powders and suspensions, Colloids Surf. A. 117, 267, 1996. 

Tunc, S. and Human. O., The effect of different molecular weight of polyfethylene glycol) on the electrokinetic and rheological properties of Na-hentonite suspensions, Colloids Surf. A, 317, 93, 2008. 

Vdovic, N. and Biscan, J., Electrokinetic of natural and synthetic calcite suspensions, Colloids Surf. A, 137, 7, 1998. 

Sadowski, Z., The role of surfactant salts on the spherical agglomeration of hematite suspension. Colloids Surf. A, 173, 211, 2000. 

Pugh, R.J. and Bergstrom, L., Surface and solution chemistry studies on galena suspensions. Colloids Surf., 19, 1, 1986. 

Garrido, L.B., Volzone, C., and Tones Sanchez, R.M., OH-Al polymers and HMP adsorption on kaolinite Experimental conditions and viscosity of deflocculated suspensions. Colloids Surf. A, 121, 163, 1997. 

B.M. WC/Co B.M. Teflon B.M. polyamide contamination) industrial scale Hard + brittle Hard + abrasive Frozen or freeze-dried plant or animal tissues [ ] Soft + brittle suspensions, colloids, emulsions... 

Physical Characteristics. The most important physical characteristic ofwaste water is its total solids content, which is composed offloating matter, matter in suspension, colloidal matter, and matter in solution. Other physical characteristics include temperature, color, and odor. 

Belloni L. Ionic Condensation and Charge Renormalization in Colloidal Suspensions. Colloids and Surfaces 1998 A140 227. 

Belloni L. Ionic condensation and charge renormalization in colloidal suspensions. Colloids and Surfaces A 1998 140 227-243. 

Radeva Ts, Petkanchin I, Varoqui R, Stoylov S. Electro-optical studies of kaolinite/polyacrylamide suspensions. Colloids Surf 1989 41 353-361. 

Petkanchin I, Bruckner R, Sokerov S, Radeva Ts. Comparison of electric light scattering and birefringence for polydisperse suspensions. Colloid Polymer Sci 1979 257 160-165. 

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