Which statement is not true about coagulants?

Which statement is not true about coagulants?

• A. Sodium chloride is a coagulant.
• B. Sodium aluminate is a coagulant.
• C. Aluminum sulfate is a coagulant.
• D. Ferrous sulfate is a coagulant.

Answer: (A)

Coagulants in water treatment are positively charged metal salts that destabilize negatively charged colloids. When added, they hydrolyze to positively charged hydroxide species, which neutralize the surface charges of suspended particles and promote the formation of larger flocs that can be settled or filtered out. This is why aluminum- and iron-based compounds are commonly used as coagulants. Sodium chloride, on the other hand, is simply table salt. It does not produce the charged hydrolyzed species needed to neutralize colloidal particles or to form flocs, so it’s not used as a coagulant. Sodium aluminate, aluminum sulfate, and ferrous sulfate all function as coagulants because they form effective hydrolysis products that neutralize particle charges and aid floc formation. Sodium aluminate and aluminum sulfate yield aluminum hydroxide flocs, while ferrous sulfate provides iron hydroxide flocs, enabling coagulation and subsequent removal of impurities.

Coagulants in water treatment are positively charged metal salts that destabilize negatively charged colloids. When added, they hydrolyze to positively charged hydroxide species, which neutralize the surface charges of suspended particles and promote the formation of larger flocs that can be settled or filtered out. This is why aluminum- and iron-based compounds are commonly used as coagulants.

Sodium chloride, on the other hand, is simply table salt. It does not produce the charged hydrolyzed species needed to neutralize colloidal particles or to form flocs, so it’s not used as a coagulant.

Sodium aluminate, aluminum sulfate, and ferrous sulfate all function as coagulants because they form effective hydrolysis products that neutralize particle charges and aid floc formation. Sodium aluminate and aluminum sulfate yield aluminum hydroxide flocs, while ferrous sulfate provides iron hydroxide flocs, enabling coagulation and subsequent removal of impurities.