Redox mine waters

Nordstrom, D. K., E. A. Jenne and J. W. Ball, 1979, Redox equilibria of iron in acid mine waters. In E. A. Jenne (ed.), Chemical Modeling in Aqueous Systems, American Chemical Society, Washington DC, pp. 51-79. 

Redox diagrams are used to express the stability of dissolved species and minerals. An example diagram is presented in Fig. 2.4, where the redox potentials of various types of aqueous systems are shown as a function of pH. It can be seen that at acidic pH, a mine water system has a very high oxidation potential (Eh > 500 mv). In... 

Bednar, A.J., Garbarino, J.R., Ranville, J.F. and Wildeman, T.R. (2005) Effects of iron on arsenic speciation and redox chemistry in acid mine water. Journal of Geochemical Exploration, 85(2), 55-62. 

Redox Equilibria of Iron in Acid Mine Waters... 

Redox Status of Acid Mine Waters Equilibrium or Disequilibrium ... 

The chemical equilibria approach used in this study have enabled us to identify which parts of an acid mine drainage system are in equilibrium and which parts are not. Our results have provided greater insight into the chemical processes of acid mine waters in particular and the redox relations of iron in general. 

V potential versus appropriate [M(NH3)6]3+ 2 couple. The redox potentials of the hexaam-mine complexes are +0.05 and -0.78 V, respectively, versus NHE in water. 

It can be converted to a water-soluble, insensitive material, not susceptible to initiation, by treatment for 15 minutes at 87°, with 30 wts of a 15% soln of Na sulfide nonahydrate (Ref 1). Amm sulfide behaves similarly, but reacts much more slowly. These procedures involve reduction of the nitro groups to amino and other groups less energetic than nitro. TNT can be rapidly rendered non-expl by treatment with isopropyl-amine in a good solvent for TNT (eg, acetone or acetonitrile) (Ref 18). This system has been studied for destroying land mines (Refs 11 18). Destruction of the nitro groups in this system apparently occurs by the base-promoted redox reactions discussed under the reaction of TNT with bases. These chemical methods produce products of unknown toxicity, and are therefore suitable only for the treatment of small amounts of material on an occasional basis Other (limited-access) reports on the disposal of TNT are listed in the following Refs (Refs 4, 6,9,19,20 33)... 

The relative proportions of arsenic species in estuarine waters are more variable because of changes in redox, salinity, and terrestrial inputs (Abdullah et al., 1995 Howard et al., 1988). Arsenic(V) tends to dominate, although M. O. Andreae and T. W. Andreae (1989) found increased proportions of As(III) in the Schelde Estuary of Belgium. The highest values occur in anoxic zones near sources of industrial effluent. Increased proportions of As(III) also occur near sources of mine effluent (M. O. Andreae and T. W. Andreae, 1989). Seasonal variations in concentration and speciation have been reported in seasonally anoxic waters (Riedel, 1993). Peterson and Carpenter (1983) reported a clear crossover in the proportions of the two species with increasing depth in the Saanich Inlet of British Columbia. Arsenic(III) represented only 5% (0.10 p,g L ) of the dissolved arsenic above the redox front but 87% (1.58p,gL ) below it. In marine and estuarine waters, organic forms of arsenic are... 

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