1974/12/01 by Donald O. Whittemore, Donald Langmuir · 1 citation
Energy · Environmental Science · #Iron oxide chemistry and applications #Mine drainage and remediation techniques #Water Quality and Pollution Assessment
paper · pdf · doi:10.1289/ehp.749173
openalex publication_date 1974/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/23
Mineralogy and specific surface area are major controls on the stabilities of ferric oxyhydroxide microparticles in natural waters. The thermodynamic stabilities of ferric oxyhydroxides, as described by the activity product in solution pK = −log [Fe3+] [OH−]3 range from pK = 37.1 for freshly precipitated amorphous oxyhydroxide to pK = 44.2 for well crystallized goethite. The sizes of suspended oxyhydroxide particles in natural waters range from less than 0.01 μm to greater than 5 μm. Oxyhydroxides precipitated in the laboratory from solutions simulating high-iron natural waters are needlelike or lathlike in shape and have mean thicknesses as small as 60 Å. Large specific surface areas resulting from the small sizes of ferric oxyhydroxide particles cause increased solubilities and thus decreased pK values. Specific surface areas of 40–170 m2/g determined for laboratory precipitates gave computed decreases in pK of 0.4 to 1.6 units.