Hydrous oxides colloidal

Johnson, R. E., Jr. (1984) Thermodynamic Description of the Double Layer Surrounding Hydrous Oxides, . /. Colloid Interface Sci. 100, 540-554. 

In this work, we address to the first point our objectives were to explore the modifications of the electrical double layer and hydrodynamic properties of a jS ferric hydrous oxide colloid in aqueous media, interacting with non-hydrolyz polyac lamide, a neutral polymer. The j8 ferric hydrous oxide particles are ellipsoidal shaped particles and the electrical double layer features can be determined through the electrical polarizability of the ellipse. Electro-optical determinations were complemented by measuring the electrophoretic mobility at various polymer coverage. 

An appreciation of the value of hydrous oxide colloids for wetting hydrophobic surfaces with water is shown by Kenney (593), who claims that certain aqueous particulate colloids can wet any known hydrophobic surfaces without chemical change. However, I have found that wetting by a silica sol occurs on certain hydro-phobic surfaces only at low pH and with an optimum particle size of silica. After the surface has been wetted by sol, rinsed, and dried, the area is rewettable only because there remains an adsorbed monolayer of silica particles bonded to the surface. The type of bonding depends on the type of hydrophobic surface. For example, a metal surface, hydrophobic because of an adsorbed film of fatty acids (grease) is made hydrophilic by the silica replacing some of the fatty acid and bonding to the oxide surface film until the area is well populated by silica. This occurs mainly at neutral... 

Recently, DHBCs have been used as a good stabilizer for the in-situ formation of various metal nanocolloids and semiconductor nanocrystals such as Pd, Pt [328-330], Au [280,328-330], Ag [331], CdS [332], and lanthanum hydroxide [333]. PAA-fe-PAM and PAA-fc-PHEA were used as stabihzer for the formation of hairy needle-Uke colloidal lanthanum hydroxide through the complexation of lanthanum ions in water and subsequent micelhzation and reaction [333]. The polyacrylate blocks induced the formation of starshaped micelles stabilized by the PAM or PHEA blocks. The size of the sterically stabilized colloids was controlled by simply adjusting the polymer-to-metal ratio, a very easy and versatile synthesis strategy for stable colloids in aqueous environment [333]. The concept of induced micelhzation of anionic DHBCs by cations was also apphed in a systematic study of the direct synthesis of highly stable metal hydrous oxide colloids of AP+, La +, Ni +, Zn ", Ca ", or Cu " via hydrolysis and inorganic polycondensation in the micelle core [334,335]. The AP+ colloids were characterized in detail by TEM [336], and the intermediate species in the hydrolysis process by SANS, DLS, and cryo-TEM [337]. 

Gerardin C et al (2003) Highly stable metal hydrous oxide colloids by inorganic polycondensation in suspension. Angew Chem Int Ed 42 3681-3685. doi 10.1002/anie.200350917... 

Matijevi i E 1976 Preparation and oharaoterization of monodispersed metal hydrous oxide sols Prog. Colloid Polym. Sol. 61 24-35... 

Sugimoto T. and Matuevic E. 1979. Colloidal cobalt hydrous oxides. Preparation and properties of monodispersed Co304. J. Inorg. Nucl. Chem. 41 165-72. 

Relaxation studies have shown that the attachment of an ion to a surface is very fast, but the establishment of equilibrium in wel1-dispersed suspensions of colloidal particles is much slower. Adsorption of cations by hydrous oxides may approach equilibrium within a matter of minutes in some systems (39-40). However, cation and anion sorption processes often exhibit a rapid initial stage of adsorption that is followed by a much slower rate of uptake (24,41-43). Several studies of short-term isotopic exchange of phosphate ions between aqueous solutions and oxide surfaces have demonstrated that the kinetics of phosphate desorption are very slow (43-45). Numerous hypotheses have been suggested for this slow attainment of equilibrium including 1) the formation of binuclear complexes on the surface (44) 2) dynamic particle-particle interactions in which an adsorbing ion enhances contact adhesion between particles (43,45-46) 3) diffusion of ions into adsorbents (47) and 4) surface precipitation (48-50). 

If a surface precipitate of metal hydroxy-polymer has formed on an adsorbent, the -pH relationship for the coated adsorbent should resemble closely that observed for particles consisting purely of the hydroxy-polymer or the hydrous oxide of the metal (15). This kind of evidence for Co(ll), La(lII), and Th(lV) precipitation on silica colloids was cited by James and Healy (15). It should be noted, however, that the increase in C toward a maximum value often occurs at pH values well below that required thermodynamically to induce bulk-solution homogeneous precipitation of a metal hydrous oxide (15, 16). If surface precipitation is in the incipient stage under these conditions, it must be a nucleation phenomenon. James and Healy (15) argue that the microscopic electric field at the surface of a charged adsorbent is sufficiently strong to lower the vicinal water activity and induce precipitation at pH values below that required for bulk-solution precipitation of a metal hydrous oxide. 

E. Matijevic, Preparation and properties of monodispersed colloidal metal hydrous oxides. Pure Appl. Chem. 50(9-10), 1193-1210 (1978). 

Kraus, K. A. and J. S. Johnson. 1966. Colloidal hydrous oxide hyperfiltration membrane. U.S. Patent 3,413,219. 

Anderson, P.R. Malotky, D.T. (1979) The adsorption of protolyzable anions on hydrous oxides at the isoelectric pH. J. Colloid Interface Sci. 72 413-427... 

Blesa, M.A. Maroto, A.J.G. (1986) Dissolution of metal oxides. J. chim. phys. 83 757—764 Blesa, M.A. Matijevic, E. (1989) Phase transformation of iron oxides, oxyhydroxides, and hydrous oxides in aqueous media. Adv. Colloid Interface Sci. 29 173-221 Blesa, M.A. Borghi, E.B. Maroto, A.J.G. Re-gazzoni, A.E. (1984) Adsorption of EDTA and iron-EDTA complexes on magnetite and the mechanism of dissolution of magnetite by EDTA. J. Colloid Interface Sci. 98 295-305 Blesa, M.A. Larotonda, R.M. Maroto, A.J.G. Regazzoni, A.E. (1982) Behaviour of cobalt(l 1) in aqueous suspensions of magnetite. Colloid Surf. 5 197-208... 

Gardner, W.K. Parbery, D.G. Barber, D.A. (1982) The acquisition of phosphorus by Lu-pinus albus L. I. Some characteristics of the soil/root interface. Plant Soil 68 19-32 Garg, A. Matijevic, E. (1988) Preparation and properties of uniform coated colloidal particles. II. Chromium hydrous oxide on hematite. Langmuir 4 38-44 Garg, A. Matijevic, E. (1988) Preparation and properties of uniform coated colloidal parti-... 

In Skirmer, H.G.W. Fitzpatrick, R.W. (eds.) Biomineralization processes of iron and manganese. Catena Verlag, Cremhngen-Destedt, Catena Suppl. 21 75—99 Ghoneimy, H.F. Morcos.T.N. Misak, N.Z. (1997) Adsorption of Co and Zn ions on hydrous Fe(lll), Sn(lV) and mixed Fe(lll)/ Sn(IV) oxides. Part 1. Characteristics of the hydrous oxides, apparent capacity and some equilibria measurements. Colloids Surfaces A. 122 13-26... 

Harvey, D.T. Linton, R.W. (1984) X-ray photoelectron spectroscopy (XPS) of adsorbed zinc on amorphous hydrous ferric oxide. Colloids Surfaces 11 81-96... 

Hayes, KF. Papelis, C. Leckie, J.O. (1988) Modeling ionic strength Effects on anion adsorption at hydrous oxide/solution interfaces. J. Colloid Interface Sd. 78 717—726 Hayes, KF. Roe, A.L. Brown, G.E. Hodgson, KO. Leckie, J.O. Parks, G.A. (1987) In-situ X-ray absorption study of surface complexes Selenium oxyanions on a-FeOOH. Sdence 238 783-786... 

Kraemer, S.M. Hering, J.G. (1997) Influence of solution saturation state on the kinetics of ligand-controlled dissolution of oxide phases. Geochim. Cosmochim. Acta 61 2855-2866 Kraemer, S.M., Xu, J., Raymond, K.N. Spo-sito, G. (2002) Adsorption of Pb(II) and Eu(III) by oxide minerals in the presence of natural and synthetic hydroxamate sidero-phores. Environ. Sd. Technol. 36 1287-1291 Kraemer, S.M. Cheah, S.-F. Zapf, R. Xu, J. Raymond, KN. Sposito, G. (1999) Effect of hydroxamate siderophores on Fe release and Pb(II) adsorption by goefhite. Geochim. Cosmochim. Acta 63 3003—3008 Kratohvil, S. Matijevic, E. (1987) Preparation and properties of coated uniform colloidal partides. I. Aluminum (hydrous) oxide on hematite, diromia, and titania. Adv Ceram. Mater. 2 798-803... 

Matijevic, E. Scheiner, P. (1978) Ferric hydrous oxides sols. III. Preparation of uniform particles by hydrolysis of Fe(III)-chIoride, -nitrate, and -perchlorate solutions. J. Colloid Interface Sd. 63 509—524 Matijevic, E. (1980) Colloid chemical aspects of corrosion of metals. Pure Applied Chem. 52 1129-1193... 

Zhang,Y Kallay, N. Matijevic, E. (1985) Interactions of metal hydrous oxides with chelating agents. VII. Hematite - oxalic and citric acid systems. Langmuir 1 201-206 Zhang, Z. Boxall, C. Kelsall, G.H. (1993) Photoelectrophoresis of colloidal iron oxides. I. Hematite (a-Fe203). Colloids Surfaces. A. Physics Chemical and Engineering Aspects. 73 145-163... 

A sulfuric acid solution of the oxide (25-75% solution) can be reduced with tin, copper, zinc, and other reducing agents forming a blue solution of molybdenum blue which are hydrous oxides of non-stoichiometric compositions (see Molybdenum Blue). Reduction with atomic hydrogen under carefully controlled conditions yields colloidal dispersion of compounds that have probable compositions Mo204(OH)2 and Mo40io(OH)2. Reduction with lithium aluminum hydride yields a red compound of probable composition MosOtIOEOs. Molybdenum(Vl) oxide suspension in water also can be reduced to molybdenum blue by hydriodic acid, hydrazine, sulfur dioxide, and other reductants. 

This chapter summarizes the present state of the art of the forced hydrolysis approach by considering specific cations, particularly those of greatest practical and theoretical interest, using aqueous solutions of common salts. In addition to being economical in the manufacture of different products, the described procedure can also help in the development of a better understanding of different processes, such as corrosion of metals or formation of minerals, to mention a few. It should be emphasized that the focus of this chapter is on dispersions of narrow particle size distributions, normally designated as monodispersed systems. While a number of genera reviews have been published on monodispersed colloids (7,9-21), this chapter specifically addresses the problems related to metal (hydrous) oxides. 

Despite the fact that the hydrolysis of the ferric ion is exceedingly sensitive to various experimental parameters (temperature, pH, etc.), hematite (a-Fe203) and akageneite ((3-FeOOH) were apparently the first reasonably uniform colloidal metal (hydrous) oxides dispersions reported in the literature, as already indicated in the introduction. Since then, this family of compounds has been the most extensively investigated, with specific emphases on particle uniformity, composition, and morphology. 

References Friend, I, 78 Mellor, I, 768 Alexander, Colloid Chemistry, 4 vols. (1926-1932) Bancroft, Applied Colloid Chemistry (1926) > Bogue, Colloidal Behavior, 2 vols. (1924) Colloid Symposium Monographs, beginning 1923 Hatschek, Introduction to the Physics and Chemistry of Colloids (1922) Thomas, Colloid Chemistry (1934) Weiser, The Colloidal Salts, (1928) The Hydrous Oxides (1926) Inorganic Colloid Chemistry (1933). 

References Bancroft, J. Phys. Chem., 18, 549 (1914) Weiser, The Hydrous Oxides, Chap. I (1926) Bogue, Colloidal Behavior, Chap. XV (1924). 

Only a fraction of the total metal content of soils and sediments tends to be available for uptake by plants or biota. This fraction is generally associated with the colloidal material (i.e., clay minerals, hydrous oxides and organic matter), but views differ on the relative effects of the individual components. 

MATIJEVIC, E., Preparation and characterisation of monodispersed metal hydrous oxide sols , Progr. Colloid Polymer Sci., 61, 24-35 (1976) Monodispersed Metal (Hydrous) Oxides , Acc. Chem. Res., 14, 22-29 (1981)... 

In addition to the soluble chemical species and possible solid phase species described in the previous sections no discussion on speciation can be complete without the consideration of surface species. These include the inorganic and organic ions adsorbed on the surface of particles. Natural systems such as soils, sediments and waters abound with colloids such as the hydrous oxides of iron, aluminium, manganese and silicon which have the potential to form surface complexes with the various cationic and anionic dissolved species (Evans, 1989). 

Hayes, K.F. and Leckie, J.O. (1987) Modelling ionic strength effects of cation adsorption at hydrous oxide/solution interfaces./. Colloid Interface Sci., 115, 564-572. 

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