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Phase Interactions in Aquatic Chemistry
Published in Stanley Manahan, Environmental Chemistry, 2017
Two inorganic species are particularly important in the sequestration of heavy metals in sediments. One of these is hydrated iron(III) oxide, commonly represented as Fe2O3∙x(H2O), Fe(OH)3, or FeOOH, which coprecipitates heavy metals. This material forms when soluble iron(II) is exposed to oxidizing conditions. Under anoxic conditions, the material is reduced to soluble iron(II) (Reaction 4.2.6), which releases bound heavy metals. The second important solid that binds heavy metals consists of acid-volatile sulfides, especially FeS. Most heavy metals have a stronger affinity for sulfide than does iron(II); thus, heavy metals tend to displace Fe(II) from this compound. The conditions conducive to reduction of hydrated iron(III) oxide leading to release of sequestered heavy metal ions are also conducive to formation of FeS, which may release sulfide to reprecipitate the heavy metal ions as sulfides.
Intumescent FRs (IFRs)
Published in Asim Kumar Roy Choudhury, Flame Retardants for Textile Materials, 2020
Iron(III) oxide-hydroxide occurs naturally as four minerals, the polymorphs denoted by the Greek letters α, β, γ, and δ. Goethite, α-FeO(OH), has been used as a pigment since prehistoric times. The air oxidation of Fe(OH)2 particles in highly alkaline media leads to the epitaxial growth of α-FeOOH, a process that should be facilitated by the similarity between the anion arrangements in both phases. By changing the supersaturation, one can modify the morphology and the size distribution of the α-FeOOH particles obtained at the end of the oxidation reaction.
Effect of nitric acid contamination on mild steel corrosion in hydrofluoric acid at 25°C
Published in Corrosion Engineering, Science and Technology, 2020
R. van der Merwe, J. W. van der Merwe, L. A. Cornish
The addition of only 0.1% HNO3 to the 70% HF corrosion solution significantly affected the colour of the scales (Figure 4: Row (a)), as well as the steel substrate exposed after cleaning (Figure 4: Row (b)). In HF corrosion solutions with HNO3 (0.1, 0.5 and 1%), black scales with red-brown mottling were visible over the surfaces of all the coupons (Figures 4–6: Row (a)). Dilute HNO3 reacted with iron to produce iron nitrate, although iron nitrate is violet in colour and is readily soluble in water [22]. Thus, the red scale was most likely to be iron (III) oxide (red-brown Fe2O3 crystals), which formed when the black iron (II) oxide was further oxidised by HNO3.
Evaluation of three different glassy composites (quinary matrix designed using Cr2O3/Na2O/MnO2) in respect of radiation shielding behaviors
Published in Radiation Effects and Defects in Solids, 2021
Ozan Toker, Bayram Bilmez, Melis Ö. Toker, H. Birtan Kavanoz, Özgür Akçalı, Mehmet Yılmaz, Orhan İçelli
Iron (III) oxide (Fe2O3), is commonly found and an important iron mineral for the ceramic industry; is used to color ceramic bodies, as an additive. It is also used to improve glass fiber properties such as magnetic shielding, thermostability, and dielectric loss (26).