Some Considerations on Iron Removal

The common technique for the control and removal of iron consists of oxidation followed by solid/liquid separation. The effects of ionic strength and chloride concentration on the oxidation kinetics of ferrous iron in the mg/L range by dissolved oxygen are reported here. The rate constant at 25 °C in infinitely dilute solution is about $6\times {10}^{13}{M}^{-2}{\mathrm{atm}}^{-1}{\min }^{-1}$ and in seawater‐like conditions, $4\times {10}^{12}{M}^{-2}{\mathrm{atm}}^{-1}{\min }^{-1}\text{.}$ With atmospheric partial pressures of oxygen and $\mathrm{pH}>6\text{,}$ the chemical half‐life of ferrous iron is on the order of minutes to hours. The particle size distribution of some ferric oxyhydroxide precipitates are reported. The use of other oxidants such as chlorine and potassium permanganate versus oxygen is reviewed.