Iron removal filtration is an important step in water purification. Excess iron in water has a big impact on our body. It can cause digestive system disorders, promote tooth decay and cause skin irritation. Under the influence of solutions and atmospheric factors, iron corrodes. This phenomenon consists in oxidation to Fe2 + and Fe3 + ions, which then precipitate as rust-forming hydroxides.
Iron removal filtration
Most often, iron is found in groundwater in the form of iron (II) bicarbonate – Fe(HCO3)2. Which easily reacts with water to form sparingly soluble iron (II) hydroxide – Fe(OH)2↓(reakcja I).
Fe(HCO3)2 + 2H2O = Fe(OH)2↓ + 2H2O + 2CO2↑
The resulting iron hydroxide (II) – Fe(OH)2 during aeration of water oxidizes to the more soluble hydroxide (III) – Fe(OH)3↓, which precipitates in the form of “flocs” retained on the filters (reaction II).
4Fe(OH)2↓ + 2H2O + O2 = 4Fe(OH)3↓
Read also the articles: Softening filtration, Activated carbon filtration and Mechanical filtration.