Alumina colloidal stability

Ringenbach, E., Chauveteau, G., and Pefferkom, E.. Effect of soluble aluminum ions on polyelectrolyte-alumina interaction. Kinetics of polymer adsorption and colloid stabilization. Colloids Surf. A, 99, 161, 1995. 

Jiang, L., and Gao. L.. Effect of Tiron adsorption on the colloidal stability of nanosized alumina suspension. Mater. Chem. Phys., 80, 157. 2003. 

Figure 9.5(a) Adsorption, electrophoretic mobility, and colloidal stability isotherms for a-alumina at pH 7.2, 2 x 10 m ionic strength, and 25° C. as a function of the equilibrium concentration of sodium dodecyl sulphonate. (b) Adsorption, electrophoretic mobility, and colloidal stability isotherms for a-alumina at pH 6.9, 2 x 10 m ionic strength, and 25°C. as a function of the equilibrium concentration of sodium dodecyl sulphonate. From [12] with permission. 

Reaction of the sandwich-type POM [(Fc(0H2)2)j(A-a-PW9034)2 9 with a colloidal suspension of silica/alumina nanopartides ((Si/A102)Cl) resulted in the production of a novel supported POM catalyst [146-148]. In this case, about 58 POM molecules per cationic silica/alumina nanoparticle were electrostatically stabilized on the surface. The aerobic oxidation of 2-chloroethyl ethyl sulfide (mustard simulant) to the corresponding harmless sulfoxide proceeded efficiently in the presence of the heterogeneous catalyst and the catalytic activity of the heterogeneous catalyst was much higher than that of the parent POM. In addition, this catalytic activity was much enhanced when binary cupric triflate and nitrate [Cu(OTf)2/Cu(N03)2 = 1.5] were also present [148],... 

Catalyst-supporting materials are used to immobilize catalysts and to eliminate separation processes. The reasons to use a catalyst support include (1) to increase the surface area of the catalyst so the reactant can contact the active species easily due to a higher per unit mass of active ingredients (2) to stabilize the catalyst against agglomeration and coalescence (fuse or unite), usually referred to as a thermal stabilization (3) to decrease the density of the catalyst and (4) to eliminate the separation of catalysts from products. Catalyst-supporting materials are frequently porous, which means that most of the active catalysts are located inside the physical boundary of the catalyst particles. These materials include granular, powder, colloidal, coprecipitated, extruded, pelleted, and spherical materials. Three solids widely used as catalyst supports are activated carbon, silica gel, and alumina ... 

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

Mixing a preformed metal sol with a support material also provides a method for the preparation of supported catalysts with the colloidal metal particles attached to supports such as alumina - o, titania5. 52 d pumice.53 While this procedure gives catalysts having essentially a single size metal particle, the particles are not strongly bonded to the support which makes these materials primarily useful for vapor phase reactions. An added complication is that the citric acid commonly used to prepare the sols > >52 qj. the micellar material in which they are stabilized, can also be adsorbed on the support and, possibly, inhibit the activity of the resulting catalysts. 

Silicalite-1 membranes, supported on porous alumina ceramic discs, have been prepared by two different routes. In the first the zeolite membrane has been formed by in situ hydrothermal synthesis. Secondly a layer has been formed by controlled filtration of zeolite colloids. To optimise membrane stability, conditions have been established in which penetration of zeolite into the support sublayer occurs. The pore structure of these membranes has been characterised by a combination of SEM and Hg-porosimetry. The permeabilities of several gases have been measured together with gas mbeture separation behaviour. 

Eremenko, B.V. et al.. Stability of suspensions of alumina nanoparticles in aqueous solutions of electrolytes. Colloid J., 58, 436, 1996. 

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

Li, Ch., Yu, X., and Somasundaran, P., Effect of a comb-like amphiphihc polymer on the stability of alumina dispersions, Colloids Surf., 69, 155, 1992. 

Kosmulski, M., Adsorption of cadmium on alumina and silica Analysis of the values of stability constants of surface complexes calculated for different parameters of triple layer model. Colloids Surf. A, 117, 201, 1996. 

Singh. B.P. et al., Stability of dispersions of colloidal alumina particles in aqueous suspensions, J. Colloid Interf. Sci., 291, 181, 2005. 

---