Why does the oxygen scavenger get hot?

Oxygen scavengers, such as sodium sulfite or hydrazine, can generate heat when they react with dissolved oxygen in water. This exothermic reaction occurs due to the release of energy during the chemical reaction.

When an oxygen scavenger comes into contact with oxygen, it undergoes a chemical reaction where oxygen molecules are consumed. This reaction typically involves the reduction of oxygen to a different compound. In the case of sodium sulfite, for example, it reacts with oxygen to form sodium sulfate:

2 Na2SO3 + O2 → 2 Na2SO4

During this reaction, energy is released in the form of heat. The amount of heat generated depends on various factors, including the concentration of the oxygen scavenger, the reaction rate, and the amount of dissolved oxygen present.

The heat generated by the oxygen scavenger reaction can be beneficial in certain applications. For example, in boiler systems, the heat produced by the oxygen scavenger can help raise the temperature of the water, contributing to more efficient heat transfer and reducing the risk of corrosion caused by dissolved oxygen.

It's important to note that the heat generated by the oxygen scavenger reaction needs to be carefully managed to prevent any adverse effects, such as excessive temperature rise or pressure buildup. Proper dosing and control strategies are typically implemented to ensure safe and effective use of oxygen scavengers in various industrial processes.