Feme hydroxide

When an alkali perarsenate is added to aqueous solutions of metallic salts, precipitates containing active oxygen are obtained thus salts of the alkaline earths, zinc, cadmium, silver, mercurous mercury, lead and bismuth yield white precipitates, mercuric salts give red precipitates, copper blue, manganese pink, nickel greenish-white and ferrous salts bluish-green. With auric chloride oxygen is liberated, and with ferric chloride feme hydroxide is precipitated. 

The nascent hvdrogen reduces anv nitrates or nitrites to ammonia. Atmospheric oxygen converts the ferrous salt into colloidal feme hydroxide, a reaction that is facilitated by cascade aeration. As it coagulates and settles, the ferric hydroxide punfies the water in an analogous manner to that described for aluminium hydroxide above. The process is rather expensive, however, and for this reason some American towns have added ferrous sulphate direct to their waters. This is less satisfactory as the salt is not oxidised so readily as ferrous bicarbonate m addition to this, sulphuric acid is introduced into the water. 

Mumford Proa. Ghent. Soc., 1913, 103, 645) describes an organism through the agency of which a dilute solution of ferrous ammonium sulphate was completely oxidised to feme hydroxide m thirty-six hours at 37° 0, no iron remaining in solution. See also Ellis, Iron Bacteria (Methuen, 1920). 

Foote and Saxton, loc. at. This value is supported by the earlier results of Ruff (Ber., 1901, 34, 3417), who found that feme hydroxide, after freezing at—10° C. and -—185° C., had the composition Fe203.4 2H20. 

Many industrial wastewaters contain copper ns wall as other heavy meials. Table 17.3-1 provides the results of the ndsorbing colloid flotation of such a mixture of metals.10 The floe was feme hydroxide aad tbe surfactant was SDS. Removals are generally good (based on initial concentrations of 20 mg/L for each metal). 

The flotation of nickel with SDS and feme or aluminum hydroxide was carried our." Residual nickel concentrations of about 1 mg/L were obtained for pH values of 8-9.5 with aluminum hydroxide and SDS for ionic strength less then 0.1. Ferric hydroxide performed somewhat less satisfactorily. Nickel concentrations of 420 rag/L from plating waste were precipitated with lime slutry at pH 9.5 and floated using Daoroac "T" and Dowfroth 250. Residual nickal concentrations were generally less than 3 mg/L.10... 

NR Feme Sulfate 210 99 - Magnesium Hydroxide 210 99 y Potassium Chloride 210 99 ... 

The synthesis of M"Fe204 ferrites by coprecipitation of Fe, Co ", Ni or Mn ions is possible within the 50-100 C temperature range [94-97]. Crystallization of the spinel is not immediate as in the case of Fe " ". It involves dissolutioh-recrystallization processes from a poorly organized or amorphous precipitate consisting of hydroxides of the bivalent cation and feme hydroxyhy-droxide [96,97]. The lack of electron mobility between Co, Mn or Ni and Fe . owing to the redox potential of Fe /Fe being inferior to that of... 

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