Ferrous compounds

With aluminum sulfate, optimum coagulation efficiency and minimum floe solubiUty normally occur at pH 6.0—7.0. Iron coagulants can be used successfully over the much broader pH range of 5.0—11.0. If ferrous compounds are used, oxidation to ferric iron is needed for complete precipitation. This may require either chlorine addition or pH adjustment. 

Considerable laboratoiy work has indicated that the use of a dispersant such as sodium hexametaphosphate may assist in the stabihza-tion of the medium more recent data report the beneficial effect of the addition of polymers that reduce media viscosity while simultaneously producing a very low settling rate of the ferrous compound. This should be of great value for difficult separations, but at present no data are available from commercial operations. 

Eisenoxydul-hydrat, n. ferrous hydroxide, iron(ll) hydroxide, -oxyd, n. ferrosoferric oxide, iron(II,III) oxide, magnetic iron oxide (FeaOi). -salz, n. ferrous salt, iron(II) salt, -sulfat, n. ferrous sulfate, iron(II) sulfate, -verbindung, /. ferrous compound, iron(ll) compound. 

Spijkerman, Ruegg, and May (41) have given a modified WWJ plot which uses the WWJ calibration points but uses Gray s 4s occupation numbers (2, 35) for some ferrous compounds to determine the slope of the line for this valence state. Apparently they did not take into account the 3d orbital population given by Gray s calculations and seem to have been unable to apply similar calculations to ferric compounds. 

A similar correlation of 8 and A can be found in low spin ferric compounds, but it is studied with better advantage in the ferrous series, where the range of shifts is greater. The most positive shift in ferrous compounds consistent with fully low spin bonding appears to be in the range +0.4 +0.5 mm./sec. with respect to an iron foil absorber deflned... 

The presence of iron in vegetable ash has been known since the beginning of the eighteenth century. Although iron is not a constituent of the chlorophyll molecule, a plant grown in a culture medium entirely free from it produces no chlorophyll. According to Roscoe W. Thatcher, plants take iron from the soil in the smallest proportion of any of the essential elements. Since ferrous compounds are toxic to plants, only the soluble ferric compounds can be utilized (195). 

The apparent exceptions to this hypothesis disappear on investigation thus iron, which is a dyad in ferrous compounds (as FeCl,), a tetrad in cubical pyrites (FeS,"), and a hexad in ferric acid (FeO,Ho,), is apparently a triad in ferric chloride (FeCl,) but the vapour-density of ferric chloride shows that its formula must be doubled—that, in ct, the two atoms of the hypothetical molecule of iron (FeJ have not been com-... 

Edmondson et al (1971), who studied the enrichment of whole milk with iron, found that ferrous compounds normally caused a definite oxidized flavor when added before pasteurization. Aeration before addition of the iron reduced the off-flavor. The authors recommended the addition of ferric ammonium citrate followed by pasteurization at 81 °C. Kurtz et al. (1973) reported that iron salts can be added in amounts equivalent to 20 mg iron per liter of skim milk with no adverse flavor effects when iron-fortified dry milk is reconstituted to skim milk or used in the preparation of 2% milk. Hegenauer et al. (1979A) reported that emulsification of milk fat prior to fortification greatly reduced lipid peroxidation by all metal complexes. These researchers (Hegenauer et al. 1979B) concluded that chelated iron and copper should be added after homogenization but before pasteurization by a high-temperature-short-time process. 

Ferrous compounds [see specific compounds under Iron(II)] Filters, for solutions, 3 16 for use with hydrogen atmosphere, 2 163... 

Other Papers.—Various iron species prepared by the vacuum pyrrolysis of acetyl-ferrocene-furfural resins at 400°C have been studied by Mossbauer spectroscopy. These consist of an amorphous glass-like carbon matrix containing free iron atoms, Fe+ ions, iron clusters, superparamagnetic iron, and ferromagnetic iron.333 The effect of pressure of up to 50kbar on the absorption spectra of five iron(m), two iron(n) and one mixed valence compound has been studied. In six of the compounds, but not in basic ferric acetate or soluble Prussian Blue, the observed pressure-induced bands were assigned to d-d transitions of converted iron(n) for the ferric compounds and to spin-forbidden d-d bands for the ferrous compounds. The charge-transfer band from iron(n) to iron(m) in soluble Prussian Blue showed a blue shift at pressures up to 7.2 kbar.334... 

Mattoo, B.N., I960. Characteristics of equilibria in systems of ferric-ferrous compounds on the basis of a new treatment of Lapteva s experimental data. Zhurn. Prikl. Khimii (J. App. Chem.), 33 2015-2019 (in Russian). 

Ferrous Compounds. — The preparation, properties, and tests of ferrous compounds are shown by the... 

Experiment 190. — To a little ferric chloride solution add (i) sodium hydroxide solution. The precipitate is ferric hydroxide. Describe it. Add to ferric chloride solution (2) a little solution of potassium ferricyanide. Compare the negative result with (2) in Exp. 189. Add as above (3) a little solution of potassium thiocyanate. The rich wine-red coloration is caused by the soluble ferric thiocyanate. This test distinguishes ferric from ferrous compounds. Add as above (4) a little solution of potassium ferrocyanide. The precipitate is ferric ferrocyanide. Describe it. 

Experiment 192. — (a) To a solution of fresh or freshly washed ferrous sulphate add a little hydrochloric acid, warm gently, and then add a few crystals of potassium chlorate. After heating a short time, test portions of the liquid for a ferric and a ferrous compound. 

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