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Iron Removal from Water by Precipitation in Bicarbonated Water: Influence of Crystallization Companions

Yahouza Z, Manzola AS, Amadou H and Laouali MS

Natural waters, especially in the Tahoua region, which are very salty, have a very high concentration of iron. They are the site of a significant precipitation of Fe(OH)3 in the water supply pipes. Ferrhydrite is formed in Dan Daji Illela's waters at 30°C. In order to understand the behavior of natural waters, we studied the influence of ions frequently encountered in them (Ca2+, Mg2+, Cl-, Na+, and SO42-) on the precipitation of iron in a bicarbonate medium. This study will allow us to determine if the addition of a particular ion can modify the behavior of water. Thus we studied the influence of Na+, Cl-, Mg2+, Ca2+ and SO42- ions at 30°C on the polymorphic transformations of Fe(OH)3. The experiments were performed in the bicarbonate medium with a concentration of 488 mg/L, in the presence of 5 mg/L of iron, at pHi (initial pH at the beginning of the experiment) and at room temperature for a precipitation time of 60 min. The Na+ and Cl- ions have no effect on the precipitation of Fe(OH)3 and promote the formation of the three varieties : ferrihydrite, lepidocrocite and goethite. Ca2+, Mg2+ and SO42- ions inhibit the formation of Fe(OH)3. The SO42- ions are directed towards the formation of the three varieties with the predominance of lepidocrocite. Ca2+ ions direct towards the formation of the three varieties with the predominance of goethite. The Mg2+ ions orient towards the formation of the three varieties with the predominance of ferrihydrite.