Alkalinity of boiler water may be raised by adding______.

Alkalinity of boiler water may be raised by adding______.

• A. Caustic soda
• B. Lime
• C. Sodium hypochlorite
• D. Sodium carbonate

Answer: (A)

Alkalinity in boiler water is increased by adding strong bases that supply hydroxide ions, which raise both pH and the amount of alkalinity available to neutralize acids. Caustic soda (sodium hydroxide) does this directly by dissolving to Na+ and OH−, increasing hydroxide concentration and therefore alkalinity reliably. Lime (calcium hydroxide) can raise alkalinity too, but it brings calcium into the system and tends to form sludge or interacts with other ions to create scale, which is undesirable in boiler operation. Sodium hypochlorite is primarily an oxidizer and does not meaningfully raise alkalinity. Sodium carbonate adds carbonate ions, which also raises alkalinity but can promote scale formation with hardness and is less desirable in boiler water treatment. Therefore, the most straightforward and preferred way to raise alkalinity is by adding caustic soda.

Alkalinity in boiler water is increased by adding strong bases that supply hydroxide ions, which raise both pH and the amount of alkalinity available to neutralize acids. Caustic soda (sodium hydroxide) does this directly by dissolving to Na+ and OH−, increasing hydroxide concentration and therefore alkalinity reliably.

Lime (calcium hydroxide) can raise alkalinity too, but it brings calcium into the system and tends to form sludge or interacts with other ions to create scale, which is undesirable in boiler operation. Sodium hypochlorite is primarily an oxidizer and does not meaningfully raise alkalinity. Sodium carbonate adds carbonate ions, which also raises alkalinity but can promote scale formation with hardness and is less desirable in boiler water treatment. Therefore, the most straightforward and preferred way to raise alkalinity is by adding caustic soda.