Kinetics of bromochloramine formation and decomposition

Area of Science:

• Environmental Chemistry
• Water Chemistry
• Chemical Kinetics

Background:

• Monochloramine is a key disinfectant in water treatment.
• Bromochloramine is a disinfection byproduct formed from monochloramine and bromide.
• Existing models struggle to accurately predict bromochloramine behavior.

Purpose of the Study:

• To investigate the kinetics of bromochloramine formation and decomposition.
• To evaluate the influence of pH, reactant concentrations, and buffer on bromochloramine dynamics.
• To develop and validate an extended kinetic model for bromochloramine.

Main Methods:

• Batch experiments were conducted to monitor bromochloramine formation and decay.
• Kinetic data were collected under varying pH, monochloramine, bromide, phosphate, and ammonia concentrations.
• An extended kinetic model was developed and fitted to experimental data using least-squares regression.

Main Results:

• Monochloramine decay rate increased with lower pH and higher bromide concentrations.
• Bromochloramine concentration peaked and then decreased, influenced by phosphate and ammonia levels.
• The proposed extended model showed good agreement with experimental data across tested conditions.

Conclusions:

• The developed extended model successfully captures bromochloramine formation and decomposition kinetics.
• Understanding these kinetics is crucial for managing disinfection byproduct formation in water treatment.
• Model accuracy may be limited at very low pH and high bromide concentrations.