What is the optimal pH range for ferric salts?

The optimal pH range for ferric salts is 4 to 11. This range is important for the effectiveness of ferric salts as coagulants in water treatment processes. Within this pH interval, ferric salts are able to effectively react with contaminants, facilitating the removal of suspended solids, organic matter, and other impurities from water through coagulation and flocculation.

At pH levels below 4, ferric ions can become more soluble, resulting in less effective coagulation because fewer particles can be removed, which might hinder treatment efficiency. Conversely, at pH levels above 11, ferric salts may precipitate out and become less effective as a coagulant, limiting their interaction with contaminants. Therefore, the pH range of 4 to 11 is considered ideal to balance solubility and coagulation capabilities.

Other options do not reflect the broad effectiveness of ferric salts across the necessary conditions found in typical water treatment processes.