Iron Oxy/Hydroxides Flashcards
What is the name of alpha - Fe2O3 ? And colour? And packing type ?
Hematite, blood red, HCP
What is the name of gamma - Fe2O3 ? And colour ? And packing type?
Maghemite, brown, CCP
What is the name of Fe3O4 ? And colour? And packing type ?
Magnetite, CCP
What is the name of delta - FeOOH ? And colour? And packing type ?
Feroxyhyte, brown, HCP
What is the name of alpha - FeOOH ? And colour? And packing type ?
Goethite, yellow/brown, HCP
What is the name of beta - FeOOH ? And colour? And packing type ?
Akaganeite, rust brown, HCP
What is the name of FeOOH•0•4H2O ? And colour? And packing type ?
Ferrihydrite, red/brown, HCP
What is the name of gamma - FeOOH? And colour? And packing type ?
Lepidocrocite, orange, CCP
What is the name of Fe(II)Fe(III)(OH)x ? And colour? And packing type ?
Green rusts, green, HCP
How is Goethite produced ?
1) Nucleation and growth from Fe 3+ ions @ pH > 1
2) oxidation of green rusts with carbonate
3) dissolution and reprecipitation of ferrihydrite
How is akaganeite produced?
1) hydrolysis of Fe 3+ with Cl-
How is ferrihydrite produced ?
1) direct precipitation of Fe 3+ @ pH > 2
How is lepidocrocite produced?
1) direct oxidation of Fe2+
2) oxidation from green rusts @ pH 5-7
How are green rusts produced?
1) slow hydrolysis of goethite/ferrihydrite/haemitite with Fe2+ ions
2) rapid hydrolysis of Fe(II) solution or ferrihydrite
How is maghemite produced ?
1) thermal dehydroxylation of lepidocrocite
2) careful oxidation of magnetite
How is hematite produced ?
1) thermal transformation from feroxyhyte, maghemite, goethite @200-400 degrees C
2) dehydration and rearrangement of nano-sized ferrihydrite
How is feroxyhyte produced?
1) rapid oxidation of iron II salts
How is magnetite produced?
1) oxidation and dehydration of Fe(II) salts at pH >8
2) from ferrihydrite with Fe2+ ions at pH 9-10
What happens to Fe3+ ions/what are they converted to and how?
Deprotonation to Fe(OH)^(3-x)_x
What happens to Fe2+ ions/what are they converted to and how?
Oxidation and Deprotonation to Fe(OH)^(3-x)_x and Fe(OH)^(2-x)_x
Which forms of iron oxides/hydroxides are strongly magnetic? What is the disadvantage of these compounds ?
Maghemite and magnetite are stongly magnetic (superparamagnetic) but have small SA, needed for adsobence capacity
(High SA = ferrihydrite)
