Iron oxide process basic chemistry

Although this chemistry is complex, the basic process is reduction of iron oxide by carbon in an atmosphere depleted of oxygen. Archaeologists have found ancient smelters in Africa (in what is now Tanzania) that exploited this chemistry to produce iron in prehistoric times. Early African peoples lined a hole with a fuel of termite residues and added iron ore. Chamed reeds and charcoal provided the reducing substance. Finally, a chimney of mud was added. When this furnace was fired, a pool of iron collected in the bottom. 

Besides porosity surface chemistry of the carbonaceous matrix, inorganic matter in activated carbon and its chemical specification have shown to be important for the process of MM adsorption/oxidation. In the study of the performance of various commercial carbons it was found that such ash constituents such as potassium and iron can be critical for the feasibilify of MM removal. While potassium, which is the natural component of coconut shell-based carbon enhances capacity by shifting the dissociation of MM to the right via basic environment, iron plays a role for catalytic oxidation via redox reactions. It is almost always present in an inorganic matter of carbons form such natural sources as coal, wood, or peat and its effect on MM adsorption /oxidation can be summarized in the following sequence of reactions (in the presence of moisture and ojQ gen) [139] ... 

The mineral bauxite, which is a mixed hydroxide of iron and aluminum, is the raw material at the origin of the industrial chemistry of aluminum compounds. Bauxite is transformed into sodium-contaminated gibbsite in the so-called Bayer process (32,33). Industrial Bayer-type gibbsite can be redissolved in acids or in strongly basic solutions, and from these solutions aU other aluminum compounds are produced including aluminum hydroxides and oxides (34,35). 

Figure 7 illustrates the electrochemial redox chemistry in acetronitrile for several coordination complexes of iron [Fe (MeCN)4, Fe CL, and Fe (acac)s (acac = acetylacetonate)] in relation to that for two iron organometallics [Fe (Cp)2 and Fe (CO)s (iron-pentacarbonyl) both stable 18-electron systems]. In MeCN, Fe (MeCN)4" is the only charged species of the group. It is reversibly oxidized (II/III couple E1/2, -I-1.6 V vs SCE). The uncharged Fe Cb molecule is reversibly reduced (Ill/n couple Ei/2, -1-0.2 V vs SCE) to giveFe Cl, which is reduced by an irreversible two-electron process to iron metal (Ep,c -L5 V vs SCE). The more basic Fe (acac)3 molecule is reversibly reduced (ni/n couple Ei/2, -0.7 V vs SCE), but does not exhibit a second reduction peak. The III/II reduction potentials for these three coordination complexes are a measure of their relative electrophilicity (Lewis acidity). 

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