Example Predominantly inorganic nanoparticle formation in acid drainage

Example predominantly inorganic nanoparticle formation in acid drainage 

Very low pH solutions derived by weathering of metal sulfide-rich rocks (sulfuric acid-rich solutions) carry high concentrations of dissolved ferrous and ferric iron, aluminum, and other metals into the surrounding environment. Solutions at, and near acid 

In addition to ferrous iron, ferric iron can be very abundant in acid drainage solutions, especially where the activity of ferrous iron-oxidizing prokaryotic microorganisms is high (see below for details). In fact, the observed iron speciation may be largely determined by the balance between microbial ferrous iron oxidation rates and the rates at which ferric iron is reduced by oxidation of sulfide, sulfur, and sulfoxy species. 

Schwertmannite, is a common nanoparticle-product of neutralization of sulfuric acid-rich solutions (Bigham et al. 1994). The original structural analysis indicated that sulfate was contained within tunnels similar to those found in akaganeite (FeOOH). However, recent work by Waychunas et al. (2001) suggests that this is a defective, nanoporous phase and that sulfate occupies inner and outer sphere positions on the surface, and probably on the internal surfaces of defect regions within the structure. 

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