freechlorine

Free chlorine refers to the active forms of chlorine that are available to disinfect water. It is typically measured in parts per million (ppm) or milligrams per liter (mg/L). The primary forms of free chlorine in water are hypochlorous acid (HOCl) and the hypochlorite ion (OCl-). The balance between these two forms is dependent on the pH of the water. At lower pH levels, hypochlorous acid, which is a more potent disinfectant, is more prevalent. As the pH increases, the proportion of hypochlorite ion increases, and its disinfection efficacy decreases.

Free chlorine is added to water sources as a disinfectant to kill harmful microorganisms such as bacteria, viruses, and protozoa. It is widely used in municipal water treatment, swimming pools, and spas. The effectiveness of free chlorine as a disinfectant is influenced by several factors, including the concentration of free chlorine, contact time, temperature, pH, and the presence of organic matter or other interfering substances. Organic matter can react with free chlorine to form disinfection byproducts, some of which are of health concern.

Maintaining an adequate level of free chlorine residual is crucial for ensuring continuous disinfection as water travels through distribution systems or remains in a treated body of water. If the free chlorine level drops too low, the water can become vulnerable to recontamination. Conversely, excessively high levels of free chlorine can lead to aesthetic issues like taste and odor problems and can potentially cause irritation. Therefore, careful monitoring and adjustment of free chlorine levels are essential for effective water treatment and public health protection.