Iron colloid

Also, basic factors such as the transport of materials, residual hardness, ion leakage, soluble iron, colloidal silica and clays, and other contaminants, which can produce scales and deposits in the FW lines and other parts of the pre-boiler section, may also produce similar detrimental effects in the boiler section. In the boiler itself, however, the buildup rate may be quicker and the results may be more devastating. 

Suslick KS, Fang M, Hyeon T (1996) Sonochemical synthesis of iron colloids. J Am Chem Soc 118 11960-11961... 

Effluents emerging from sulfide-rich waste-dumps have special characteristics, such as very low pH (< 4), high metal solubility and presence of iron colloids, which provokes water turbidity and precipitation of ochre-products. These effluents are generically named acid mine drainage (AMD), since they result, primarily, from mineral-water interactions involving some sulfide minerals that typically produce acidity upon oxidative dissolution. 

Rich, H. W. and Morel, F. M. M. (1990). Availability of well-defined iron colloids to the marine diatom Thalassiosira weissflogii, Limnol. Oceanogr., 35, 652-662. 

Cantrell, K.J. and Kaplan, D.I., Zero-valent iron colloid emplacement in sand columns, /. Environ. Eng., 123(5), 499-505, 1997. 

Let us give some experimental data on the electrolyte concentrations that produce coagulation of iron colloids. From Table VIII it is seen that the maximum coagulating action is exerted by divalent anions and, primarily, by disseminated sulfate ion. 

When thermal volcanic waters react with aerated surface waters, the appearance of ferric iron colloids is quite permissible. However, there are no organic compounds of fulvic acid t)q)e in volcanic waters and only colloidal silica could act as a stabilizer. At the same time there often is sulfur in thermal solutions, the stable form of which in the presence of free oxygen is the S04 ion—the main coagulant of colloidal iron. For this reason the possibilities of colloidal transport of iron from volcanic sources to sedimentary basins are limited. A high COj content in the hydrosphere and atmosphere does not exert a stabilizing effect on Fe(OH)3 colloids. 

Thus regardless of their origin, colloidal solutions of iron could hardly have accomplished the transport of a substantial amount of ore material. Coagulation of ferric iron colloids, even those stabilized by colloidal silica, already had occurred to a substantial extent in near-shore zones or even in rivers, under the influence of a relatively small increase in concentration of electrolytes. 

An acetylene may be reduced to an olefin by sodium in liquid ammonia, ° by electrolytic reduction at a spongy nickel cathode, or by partial hydrogenation over metal catalysts. Catalysts for the hydrogenation include nickel, ° iron, colloidal palladium, and palladium on barium sulfate or calcium carbonate. Pure trans olefins are obtained from dialkylacetylenes by reduction with sodium in liquid ammonia. The yields ate better than 90%. Catalytic hydrogenation leads to mixtures of cis and trans olefins in which the cis isomers predominate. ° Mono- and di-arylacetylenes have also been reduced. ... 

Pokrovdd O. S. and Schott J. (2002) Iron colloids/organic matter associated transport of major and trace elements in small boreal rivers and their estuaries (NW Russia). Chem. Geol. 190, 141-181. 

Davis, C. C., Knocke, W. R., and Edwards, M., 2001, Implications of aqueous silica sorption to iron hydroxide Mobilization of iron colloids and interference with sorption of arsenate and humic substances Environmental Science Technology, v. 35, p. 3158-3162. 

For trivalent metals the influence of humic substances present in diluted seawater is shown by the formation of negatively charged species, which might be attributed to metal-humic substance complexes (especially pronounced for fulvic acid). The presence of humic substances, even at lower concentrations, solubilizes iron. This is partly evident by the formation of the cationic species, which are not found in estuarine or seawater unless humic substances are added. These effects might also be attributed to the stabilization of iron colloids in water rich in humic substances. 

The extent of organics deposition depends on the iron concentration. This is similar to the effects observed with calcium concentration, except that no flux decline is observed with FeCfc This may indicate that the structure of the complexes formed is different due to the higher charge of the iron colloids. In the next section deposit morphology studies are reported. 

The complex-formation of polysaccharides with alkali metals and alkaline-earth metals has already been discussed in this Series. A dextran-iron complex has been used in the experimental therapy of synovitis, and chondroitin sulfate-iron colloids have been prepared. The swelling of cellulose in aqueous solutions of zinc chloride depends on the formation of a complex with the vicinal 2- and 3- hydroxyl groups of the repeating unit. ... 

A method for the production of stable iron colloids in solution has been developed." Sonication of Fe(CO)5 in the presence of a polyvinylpyrrolidone (PVP) stabilizer yielded an iron colloid with a particle size ranging from 3 to 8nm, while sonication in oleic acid yielded colloids with a uniform size of 8nm. Heating of the resulting colloids yielded bcc-Fe. The colloids were superparamagnetic, with a saturation magnetization of 101 emug , compared to a saturation magnetization of 123 emu g for a typical iron-based ferrofluid. 

Over the years, the precipitation of iron oxides and hydroxides from acidic solutions has received considerable attention in various fields, such as catalyst synthesis, environmental sciences and industrial processes [e.g. 22-29]. Freshly formed iron hydroxide particles help to control pollution in aquatic systems, e.g. by fixation and transport of phosphates, heavy metals and other reactive inorganic and/or organic species [30-33]. The high reactivity of these iron phases is mainly due to their small size. The formation and aggregation of iron colloids, which occurs in continental and marine aquatic systems [22, 34-38], is also employed in water and wastewater treatments [35, 39,40]. 

Martino, M., Stoker, M., Hicks, M., Bartholomew, C.H., Sault, A.G., Kawola, J.S. The synthesis and characterization of iron colloid catalysts in inverse miceUe solutions. Appl. Catal. A 161, 235-248 (1997)... 

Iron oxide Iron (111) oxide Black oxide of iron Colloidal iron oxide... 

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