Ferric oxide, adsorption

A detailed study of the physical and chemical adsorption of water on three xerogels, ferric oxide, alumina and titania, as well as on silica (cf. p. 272) has been carried out by Morimoto and his co-workers. Each sample was outgassed at 600°C for 4 hours, the water isotherm determined at or near 20°C, and a repeat isotherm measured after an outgassing at 30 C. The procedure was repeated on the same sample after it had been evacuated at a... 

This concept may be invoked to account for electrolyte formation in microcracks in a metal surface or in the re-entrant angle formed by a dust particle and the metal surface. More importantly, it can also explain electrolyte formation in the pores of corrosion product and hence the secondary critical humidity discussed earlier. Ferric oxide gel is known to exhibit capillary condensation characteristic and pore sizes deduced from measurements of its adsorptive capacity are of the right order of magnitude to explain a secondary critical relative humidity as70 7o for rusted steel . 

An example of chemical adsorption is the reaction between hydrogen sulfide and ferric oxide ... 

Pigna M, Colombo C, Violante A (2003) Competitive sorption of arsenate and phosphate on synthetic hematites (in Italian). Proceedings XXI Congress of Societa Italiana Chimica Agraria SICA (Ancona), pp 70-76 Quirk JP (1955) Significance of surface area calculated from water vapour sorption isotherms by use of the B. E. T. equation. Soil Sci 80 423-430 Rancourt DG, Fortin D, Pichler T, Lamarche G (2001) Mineralogical characterization of a natural As-rich hydrous ferric oxide coprecipitate formed by mining hydrothermal fluids and seawater. Am Mineral 86 834-851 Raven K, Jain A, Loeppert, RH (1998) Arsenite and arsenate adsorption on ferrihydrite kinetics, equilibrium, and adsorption envelopes. Environ Sci Technol 32 344-349... 

Amino acids Adsorption on ferric oxide Io exchange chromatography (IEC) 3 ig/l [511,512]... 

Furthermore the surface complex formation with Zn(II) has been determined from adsorption studies in 10 3 M suspensions of hydrous ferric oxide with dilute (10 7 M) Zn(II) solution. It can be described by the reaction... 

This section includes the majority of physically adsorbed substances, and it is only in the exceptional cases that the loss of entropy can be attributed to the loss of particular degrees of freedom. In Table VII are given an extract of Foster s results for adsorptions on ferric oxide and silica gels together with the loss in entropy calculated for the loss of translational movement normal to the surface. In each case the area... 

Adsorptions on Ferric Oxide and Silica Gels (Standard State 6 = )... 

The so called hydrous ferric oxide, HEO , i.e. 2-line ferrihydrite, has been a classic sorbent for all kinds of adsorption studies (see Jambor and Dutrizac, 1998) and Dzombak and Morel (1990) have devoted a whole book to the results of these studies. 

Anderson, P.R. Benjamin, M.M. (1985) Effects of silicon on the crystallization and adsorption properties of ferric oxides. Environ. Sci. Techn. 19 1048-1053... 

Adsorption of potential-determining ions at the ferric oxide-aqueous electrolyte interface. J. Phys. Chem. 71 550-558... 

Charlet, L. Manceau, A.A. (1992a) X-ray absorption spectioscopic study of the sorption of Cr(III) at the oxide/water interface. II. Adsorption, coprecpitation, and surface precipitation on hydrous ferric oxide. J. Colloid Interface Sd. 148 443-458 Charlet, L. Manceau, A.A. (1992) X-ray absorption spectroscopic study of the sorption of Cr(III) at the oxide-water interface. J. Colloid Interface Sd. 148 425-442 Chatellier, X. Fortin, D. West, M.M. Leppard, G.G. Ferris, F.G. (2001) Effect of the presence of bacterial surfaces during the synthesis of Fe oxides by oxidation of ferrous ions. Fur. J. Mineral. 13 705-714 Cheetham, A.K. Fender, B.E.F. Taylor, R.I. (1971) High temperature neutron diffraction study of Fei. O. J. Phys. C4 2160-2165 Chemical Week (1988) Glidderfs anti rust secret is out." 15 10... 

Kanai, H., Navarrete, R.C., Macisko, C.W. Scriven, L.E. (1992) Rheol. Acta 31 333 Kandori, K. Ishikawa,T. (1991) Selective adsorption of water on amorphous ferric oxide hydroxide. Langmuir 7 2213-2218 Kandori, K. Aoki,Y. Yasukawa, A. Ishikawa, T. (1998) Effects of metal ions on the morphology and structure of hematite particles produced from forced hydrolysis reaction. 

Manceau, A. Charlet, L. (1994) The mechanism of selenate adsorption on goethite and hydrous ferric oxide. J. Colloid Interface Sci. 168 87-93... 

Onari, S. Arai,T. Kudo, K. (1977) Infrared lattice vibrations and dielectronic dispersion in a- Fe203. Phys. Rev. B16 1717 Onoda, G.Y. de Bruyn, P.L. (1966) Proton adsorption ot the ferric oxide/aqueous solution interface. I. A kinetic study of adsorption. Surface Sd. 4 48—63... 

Res. Kyoto 42 505-510 Takai,T. Kozawa, A. (1976) ZIA (zinc ion adsorption) data of some ferric oxides and hydroxides. Denki Kagaku oyobi Kogyo Butsuri Kagaku 44 365—367... 

After an extensive study of the adsorption of arsenious oxide by metallic hydroxides,3 Sen concluded that this type of adsorption resembles that of cations by manganese dioxide, and that the chemical affinity between the adsorbent and the substance adsorbed plays an important part, thus differing from adsorption by charcoal. It has been observed that soils having a high absorption capacity for bases also absorb the arsenite ion from solutions of 0-001 to 0-01X concentration.4 The absorption increases with time, without reaching an end-point, and the process follows the normal adsorption equation C1=kC1Jn. The addition of ferric oxide or calcium carbonate to the soil considerably increases the capacity for absorption, but such salts as calcium sulphate or copper sulphate have no effect. 

The most general feature of the adsorption behavior of metal ions at solid-aqueous solution interfaces is the abrupt rise in adsorption over a narrow pH range. This has been illustrated, for example, for manganese adsorption on glass (2), cobalt on hydrous ferric oxide (8), manganese on hydrous manganese oxide (12), protactinium on glass (14), and... 

Typically limit to 0.5 ppm total Fe maximum in the cooling water. Above this level, phosphonate can be used to control problems initiated by iron. However, if the total Fe rises to 3.0 ppm, adsorption of the phosphonate onto the iron takes place and a loss of inhibitor function can occur. Iron salts present a serious fouling risk in cooling systems. Dissolved iron quickly oxidizes (especially where chlorine, bromine, or other oxidizing biocides are used) and forms ferric oxide/hydroxide, which acts as a flocculant,... 

Dyck W. 1967. Adsorption and coprecipitation of silver on hydrous ferric oxides. Can J Chem 46 1441-1444. 

Wilkie, J.A. and Hering, J.G. (1996) Adsorption of arsenic onto hydrous ferric oxide effects of adsorbate/adsorbent ratios and co-occurring solutes. Colloids And Surfaces A-Physicochemical and Engineering Aspects, 107, 97-110. 

Figure 7. Langmuir isotherms for adsorption of pyridine from cyclohexane onto ferric oxide. Conditions heat of adsorption, —8.8 kcal/mol and area per pyridine, 87 A2. Key A, 45°C and O, 25°C. (Reproduced, with permission, from Ref. 33. Copyright 1981, NACE.)...

CCM to calculate phosphate adsorption by a hydrous ferric oxide as a function of pH. The proportion of added [H3P04]t adsorbed (a,) is given by the sum of the surface phosphate species divided by [H3P04]t. The different surface phosphate species are shown as proportions of the total number of surface sites [=SOH°]t. 

Complexation by metal oxides and clays. The adsorption processes of metals on silica, alumina, hydrated ferric oxide and a range of other minerals are well documented for laboratory studies performed with synthetic materials (Buffle, 1988 Dzombak and Morel, 1990 Stumm, 1992). The approaches described for major sites are applicable in this case. Nevertheless, the relevance of these data to natural water... 

Fig. 1. Changes in the adsorption activity of ferric oxide after heating in oxygen (curve o) and in nitrogen (curve x). The quantities of ferric oxide required for adsorption of a fixed quantity of the adsorbate are shown on the abscissa. It will be seen that the adsorption capacity of a ferric oxide preparation declines more rapidly if it has been preheated in nitrogen than if it has been heated in oxygen.

The observed frequency and the low adsorption enthalpy are similar to those found for CO on the prismatic faces of chromia and ferric oxide. This comparison suggests that the electric fields at Al3+ centers sensed by CO are very weak. The reason for the predominance of faces characterized by highly shielded cations may be related to the high temperature of sintering needed to form the a phase, a parameter which favors the preferential formation of homopolar faces (500, 538, 543). 

Huang YC, Fowkes FM, Loyd TB (1991) Acidic and basic nature of ferric oxide surfaces. Adsorption, adhesion, zeta potential and dispersibility in magnetic inks for hard disks. In Mittal KL, Anderson HR (eds) Acid-Base-Interactions. VSP Utrecht, p 363... 

Figure 5. Adsorption isotherms of benzene on ferric oxide gel...

These are four-parameter equations, and Lola Deming spent weeks at her desk calculating machine to fit the curves that Lambert and Clark obtained for the adsorption of benzene on ferric oxide gel (21). These isotherms are shown in Figure 5. I do not blame anyone for not using these equations, and actually very few have used them to date. Joyner and Emmett (20) were among the hardy souls who did. Clampitt and German published another paper very recently (II), which is well worth reading for all those who deal with Type IV isotherms. 

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