Die Ermittlung der Löslichkeit von Eisen(III)‐hydroxiden mit ⁵⁹Fe I Fällungs‐ und Auflösungsversuche

Abstract

The total solubility of amorphous FeIII‐hydroxide and α‐FeOOH in 3M NaClO4 has been determined using 59Fe as tracer. The solubility determination of the amorphous hydroxide extended over the pH‐range 3–14. At pH < 3.5 the results agree satisfactorily with the value calculated using the solubility‐product and the constants of hydrolysis. At pH 5–12 an average solubility of ∼ 10−7 M has been measured but the results show considerable fluctuations. Therefore a colloidal solubility has been assumed. In the alkaline range pH > 12 it could be shown that the equilibrium Fe(OH)3 + OH−⇆Fe(OH) 4− is established, the following pKS4 being found to be after 2 h ageing 4.50 ± 0.15 and after 96 h ageing 5.00 ± 0.15.

The chemistry of aqueous iron

“…9 • m-v mol/l. This observation is in agreement with recent investigations of LENGWEILER [9], who reported on the basis of experiments with radioactive iron a constant solubility of about zo -7 tool/1 for amorphous Fe(OH)3 between pH 6 to II. The results of these investigations have led to the proposal that [Fe(OH),] (s) is in equilibrium with an undissociated molecular [Fe(OH)3] (d) (reaction x4).…”

Processes controlling the heavy metal distribution in pacific ferromanganese nodules and crusts

“…Another important solution partner is colloidal ferric hydroxide (Fe(OH)3~ about 0.1 ,umol/1 in pore water; (RuPPERT 1980), the particle size of which must be in the range of 50 to several hundred ~_ (LENGWEILER et al 1961). Surfaces of such ferric hydroxide are suitable for specific adsorption of dissolved silicate anions (STUMM et al 1980).…”

The Influence of Aluminum on the Formation of Iron Oxides. IV. The Influence of [Al], [OH], and Temperature

“…This is due to the fact that the concentration of Fe(OH)4-, the soluble Fe species which feeds the growing goethite crystal, is also dependent on the KOH concentration. If pKs4[pFe(OH4)--pOH-] is taken as 5 (as given for ferrihydrite by Lengweiler et al, 1961), [Fe(OH)4 ] of the supernatant solutions can be calculated. A plot of the A1/Fe mole ratio of the goethite against the ratio "initial Ai concentration/[Fe (OH)4-] in solution" (Figure 2) indicates that the ratio of ions Table 3.…”