Akaganéite-type β-FeO(OH) nanocrystals: preparation and characterization

Nanoparticulate Iron Oxide Minerals in Soils and Sediments: Unique Properties and Contaminant Scavenging Mechanisms

“…Akaganeite is not a pure FeOX material, and requires a small amount of bound Cl ) or other ion in its tunnel structure to gain electrostatic stabilization. Nanocrystals can be synthesized by a variety of recipes/methods, and nanocrystals of size 2-6 nm have been prepared (Deliyanni et al, 2001), however little detailed structural characterization has been done on such materials.…”

Nanostructured Pure γ‐Fe2O3 via Forced Precipitation in an Organic Solvent

“…[10] At pH values between 4 and 10, hydrolysis of Fe 3 + ions in aqueous solutions of iron(iii) chloride has usually favored the formation of bFeOOH instead of a-FeOOH (favored in the presence of other counterions). [10,16,20] In one study, this has been confirmed to be due to the presence of chloride ions, where the addition of some Cl À to the solution of iron(iii) nitrate during the aging of the red polymer has led to akaganeite, while the product was goethite in the absence of the chloride ions. [20] At pH values above 10 or below 4, goethite or hematite formed, respectively, even in the presence of chloride ions where akaganeite, if formed, converted to goethite or hematite.…”

“…Goethite (a-FeOOH), ferrihydrite (Fe 5 HO 8 ¥4 H 2 O) or akagenite (b-FeOOH) are usually the initial precipitates, which are converted to crystalline low surface area a-Fe 2 O 3 upon moderate heat treatment. [10,11,16,17] The preparation of nanoscale particles of phase-pure iron oxides has been a real challenge due to the difficulties that usually accompany this process.…”

Surfactant mediated nanoparticle assembly of catalytic mesoporous crystalline iron oxide materials

“…Pardel et al have reported high catalytic activity of akaganeite for the hydroprocessing of coal [24]. Akaganeite is usually formed in the environment in the presence of chloride ions at elevated temperatures and can be prepared by the slow hydrolysis of FeCl 3 solutions at low pH with heating to 70-100 • C. It has been revealed that pH of the FeCl 3 solution is one of the major determining factors in the synthesis of akaganeite, and only low pH (<5) favours the nucleation and grow of akaganeite [2,21,25]. This may be because at higher pH values the hydroxide ion is far more competitive for structural sites than chloride.…”