How does temperature affect free chlorine residual compared to combined chlorine?

The correct understanding of the relationship between temperature and chlorine residuals is essential for effective water treatment. Free chlorine, which includes both hypochlorous acid and hypochlorite ion, is more sensitive to temperature changes compared to combined chlorine, which primarily consists of chloramines formed when ammonia reacts with chlorine.

In warmer temperatures, free chlorine tends to be more reactive, which can lead to a quicker depletion of its concentration. However, it is overly simplistic to state that free chlorine is unaffected by temperature changes, as higher temperatures typically increase the rate of reaction and can lead to faster breakdown of free chlorine, especially in the presence of organic material.

Looking at combined chlorine, which is less effective as a disinfectant than free chlorine, its stability can be affected positively or negatively based on temperature. However, unlike free chlorine, it does not dissipate as rapidly under increased temperature, maintaining its concentration longer in warmer water.

Understanding that free chlorine’s efficacy and stability are influenced by temperature can help in managing disinfection operations more effectively, as operators must account for the temperature of the water in their treatment processes.