Carbon dioxide iron role

The symposium participants resolved to urge all governments to regard the role of iron in marine production as an area of further research and not to consider iron fertilization as a policy option that significantly changes the need to reduce emissions of carbon dioxide. 

Transition metal catalysts, specifically those composed of iron nanoparticles, are widely employed in industrial chemical production and pollution abatement applications [67], Iron also plays a cracial role in many important biological processes. Iron oxides are economical alternatives to more costly catalysts and show activity for the oxidation of methane [68], conversion of carbon monoxide to carbon dioxide [58], and the transformation of various hydrocarbons [69,70]. In addition, iron oxides have good catalytic lifetimes and are resistant to high concentrations of moisture and CO which often poison other catalysts [71]. Li et al. have observed that nanosized iron oxides are highly active for CO oxidation at low tanperatures [58]. Iron is unique and more active than other catalyst and support materials because it is easily reduced and provides a large number of potential active sites because of its highly disordered and defect rich structure [72, 73]. Previous gas-phase smdies of cationic iron clusters have included determination of the thermochemistry and bond energies of iron cluster oxides and iron carbonyl complexes by Armentrout and co-workers [74, 75], and a classification of the dissociation patterns of small iron oxide cluster cations by Schwarz et al. [76]. 

Hammouche M, Lexa D, Momenteau M, Saveant JM (1991) Chemical catalysis of electrochemical reactions—homogeneous catalysis of the electrochemical reduction of carbon dioxide by iron(O) porphyrins—role of the addition of magnesium cations. J Am Chem Soc... 

The transferrins are a class of iron-binding glycoproteins which have been found in the blood serum of a variety of vertebrates and are presumably also present in moth hemolymph [see (74) and references therein], These proteins would appear to mediate the absorption and distribution of iron (75), and could play some role in the movement of carbon dioxide in the body (76). Proteins of similar characteristics, lactoferrin and conalbumin, have been isolated from milk and avian egg white respectively. It has been proposed (77) that conalbumin could prevent bacterial contamination of the egg yolk by removing free iron. A similar bacteriostatic action could be performed by lactoferrin in milk, and it is possible that this protein is involved in controlling the intestinal flora in infants (78). 

Ferredoxins, A group of electron transfer factors found in plants and bacteria, which are non-heme iron sulfur proteins and which play an important role in photosynthesis, nitrogen and carbon dioxide fixation, and respiration. They are generally classified by the presence of either 2 or 4 iron atom clusters and an equivalent amount of inor-... 

These conclusions were, of course, totally erroneous. We now know that the mass of the tree is comprised of cellulose and water. Cellulose is derived from photosynthesis (only discovered some 140 years later) involving carbon dioxide and water. And again, how ironic that the person who coined the term gas (from chaos) and effectively discovered carbon dioxide did not understand its role in his tree experiment. ... 

Her work on the participation of water as a catalyst in the oxidation of charcoal to carbon dioxide, later proven, was of great importance and anticipated the concept of catalysis (term introduced by Berzelius in 1836— wholly loosening from the Greek ). Implicit in this is also the modern concept of the chemical mechanism a stepwise, blow-by-blow account of a chemical reaction. We will illustrate this briefly with the rusting of iron—it was the Irish chemist William Higgins who first discovered the role of water in this process and he ac-... 

Carbonic acid evolved from decomposing plant residues plays a role in iron availability. In acid soils this carbon dioxide forms bicarbonates which increase the solubility of iron compounds. In alkaline—calcareous soils, however, the carbon dioxide formed acts to keep the iron in insoluble forms and thus may increase chlorosis. Brown (1961) points out that green manure crops when incorporated into moist calcareous soil often cause severe iron chlorosis to develop in deciduous fruit trees. 

A key observation behind the ocean fertilizing experiments was that iron ions play a central role in photosyrrthesis. Estimates show that 1 kg of iron may induce the removal of 3000-83,000 kg of carbon dioxide depending on the locations and external conditions. 

Free oxygen is an important agent in the decay of all rocks that contain oxidizable substances, Iron and sulphur being especially suspect. The rate of oxidation Is quickened by the presence of water Indeed, It may enter Into the reaction itself, for example, as in the formation of hydrates. However, its role is chiefly that of a catalyst. Carbonic acid is produced when carbon dioxide is dissolved in water, and it may possess a pH value of about 5.7. The principal source of carbon dioxide is not the atmosphere but the air contained in the pore spaces in the soil where its proportion may be a hundred or so times greater than it is in the atmosphere. An abnormal concentration of carbon dioxide is released when organic material decays. Furthermore, humic acids are formed by the decay of humus in soil waters they ordinarily have pH values between 4.5 and 5.0, but they may occasionally be less than 4.0. 

Other electrocatalyzed reduction reactions were less investigated, but some of them may play an important role in the near future. For example, electrochemical reduction of carbon dioxide, such as that described with iron(lll) 5,10,15,20-tetraphenylporphyrin chloride (FeTPPCl) electrostatically deposited onto carboxylated MWCNTs [205], might become a method of reducing CO2 emission, transforming it into valuable chemicals. 

The third reaction that plays an important role - above all if iron-based catalysts are used - is the unwanted formation of carbon dioxide by the water-gas shift reaction ... 

---