Mixtures Colloids Solutions

In a collaborative work with Schmid et al., the filling of nanoporous alumina membranes of various pore widths was carried out in two different ways from the decomposition of [Ru(COD)(COT)] in THF/MeOH mixtures in the absence of stabilizer [128]. The first approach involved the impregnation of alumina support with colloidal solutions of RuNPs of different sizes which were dependent on the ratio of MeOH/THF in the reaction mixture. Colloidal solutions were transferred into membranes by vacuum induction. Only a few agglomerates were observed outside of the pores whereas dense areas were located within the membrane channels. The second approach consisted of the room-temperature decomposition of [Ru(COD)(COT)] under 3 bar of Ha following the deposition of this metal precursor inside the pores. In this way, homogeneous materials displaying well-dispersed RuNPs were obtained in the pores of alumina membranes. The size of the particles depended on the pore diameter of the template. These materials were evaluated in two catalytic reactions, i.e. the hydrogenation of 1,3-butadiene and... 

In 1997, a Chinese research group [78] used the colloidal solution of 70-nm-sized carboxylated latex particles as a subphase and spread mixtures of cationic and other surfactants at the air-solution interface. If the pH was sufficiently low (1.5-3.0), the electrostatic interaction between the polar headgroups of the monolayer and the surface groups of the latex particles was strong enough to attract the latex to the surface. A fairly densely packed array of particles could be obtained if a 2 1 mixture of octadecylamine and stearic acid was spread at the interface. The particle films could be transferred onto solid substrates using the LB technique. The structure was studied using transmission electron microscopy. 

Fulda and Tieke [77] studied the effect of a bidisperse-size distribution of latex particles on the structure of the resulting LB monolayer. For this purpose, a mixed colloidal solution of particles la and lb was spread at the air-water interface. Particles la had a diameter of 434 nm, particles lb of 214 nm. The monolayer was compressed, transferred onto a solid substrate, and viewed in a scanning electron microscope (SEM). In Figure 10, SEM pictures of LB layers obtained from various bidisperse mixtures are shown. 

Induced precipitation is a collective name for processes accompanying the formation of solid phase, such as occlusion, adsorption, compound formation, formation of isomorphous mixtures, mixed crystals, colloidal solutions, etc. In... 

Ueltmam, R.N. and Green, H. "Rheological Properties of Colloidal Solutions, Pigment Suspensions, and Oil Mixtures," J. Applied Physics. 1943, 14, 569-576. 

If you watch a glass of muddy water, you will see particles in the water settling out. This is a heterogeneous mixture where the particles are large (in excess of 1000 nm), and it is called a suspension. In contrast, dissolving sodium chloride in water results in a true homogeneous solution, with solute particles less than 1 nm in diameter. True solutions do not settle out because of the very small particle size. But there are mixtures whose solute diameters fall in between solutions and suspensions. These are called colloids and have solute particles in the range of 1 to 1000 nm diameter. Table 131 shows some representative colloids. 

Stabilizer. (1) A fractionating column used to remove light gases from a material that is otherwise liquid at ambient temperatures (2) A compound capable of keeping another compound, mixture, or solution from changing its chemical nature a stabilizer can slow down a chemical reaction, keep components in emulsion form, or keep particles in a colloidal suspension from precipitating. 

The difference between macroscopic and microscopic objects is clear from everyday experience. For example, a glass marble will sink rapidly in water however, if we grind it into snb-micron-sized particles, these will float or disperse freely in water, prodncing a visibly clondy soln-tion , which can remain stable for honrs or days. In this process we have, in fact, prodnced a colloidal dispersion or solution. This dispersion of one (finely divided or microscopic) phase in another is quite different from the molecular mixtures or true solutions formed when we dissolve ethanol or common salt in water. Microscopic particles of one phase dispersed in another are generally called colloidal solutions or dispersions. Both nature and industry have found many uses for this type of solution. We will see later that the properties of colloidal solu-... 

Colloidal Solution of Gold (Red Gold Hydrosol). Pour 5 ml of distilled water and 0.3 ml of a 0.5% gold chloride solution neutralized with soda into a wide test tube. Heat the reaction mixture until it boils, next stop the heating, add in small portions 3 ml of a 96% solution of ethanol and resume heating up to the appearance of a cherry red colour of the solution. When the latter cools, pour in 0.3 ml of a 20% hydrochloric acid solution. What do you observe Does the sol coagulate ... 

Caoutchouc mixed and warmed with finely divided black amorphous selenium assumes the dark red colour of colloidal selenium. This is the first observed case of the direct reduction of an element to the colloidal condition by intimate contact with a colloid.5 The effect is probably due in large measure to stresses produced and heat generated during the mechanical working of the mixture. The presence of another colloidal substance such as albumen, gum arabic or the sodium salt of protalbic acid, renders the colloidal selenium more stable, so that it may even be separated in a solid state without losing its power of again yielding a colloidal solution on the addition of water.6... 

F. S. Brown and C. R. Bury 6 obtained colloidal solutions of phosphorus pentoxide in nitrobenzene by stirring the mixture in the presence of alcohols or organic acids. The hydroxy-compound is absorbed and peptizes the pentoxide. Traces of moisture cause coagulation. Cone. soln. set to gels on keeping. 

The reaction mixture is then treated with hydrogen in presence of 70 ml of a 1% colloidal solution of platinum. The reduction product was isolated as hydrochloride. The hydrochloride of L-phenyl-2-methyl-amino-propanol-l crystallizes from alcohol in the form of coarse prisms. MP 214°-216°C. The free base melts at 40°C. 

A gas dispersed in a gas forms a homogeneous mixture and so do not form a colloidal solution. 

The mixture is loaded out of the reactor into tank 16 to distil tetraethyllead. The tank should already be filled with ground sulfure and ferric iron chloride. Iron chloride reduces the alkalinity of the dross and improves its consistency due to the formation of the colloid solution of iron hydroxide ground sulfure is uniformly distributed through the dross, also improving its consistency and preventing clotting of lead particles. 

The applications of colloid solutions are not restricted to paints and clay. They are also to be found in inks, mineral suspensions, pulp and paper making, pharmaceuticals, cosmetic preparations, photographic films, foams, soaps, micelles, polymer solutions and in many biological systems, for example within the cell. Many food products can be considered colloidal systems. For example, milk is an interesting mixture containing over 100 proteins, mainly large casein and whey proteins [6,7]. 

There also exist complex temporary destabilization processes of colloidal solutions. For instance almost all electroneutral polymers can cause a destabilization of an originally asymmetric systems. One example is a mixture of a clay, fibers and noncharged PEO (polyethyleoxide [62]), where both type of colloids are negatively charged. If PEO is added to only clay it adsorbs, while if PEO is added to only fibers it does not adsorb at all. In a study by van de Ven et al. [63], it was shown that in the mixture clay and PEO deposited on the fibers for several hours and the complexes initially... 

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