Modeling the Kinetics of UV/Peracetic Acid Advanced Oxidation Process

Area of Science:

• Environmental Chemistry
• Water Treatment Technologies
• Advanced Oxidation Processes (AOPs)

Background:

• Peracetic acid combined with UV (UV/PAA) is a novel AOP for water treatment.
• Kinetic modeling for the UV/PAA process was previously lacking.

Purpose of the Study:

• To develop a comprehensive kinetic model for the UV/PAA process.
• To elucidate reaction mechanisms and simulate reaction kinetics.
• To provide a useful kinetic model for water treatment applications.

Main Methods:

• Radical scavenging experiments using 2,4-hexadiene.
• Kinetic modeling to determine quantum yield and rate constants.
• Simultaneous quenching of hydroxyl radicals (•OH) and methylperoxyl radicals (CH3C(O)OO•).

Main Results:

• Accurate quantum yield of PAA under UV254 determined (Φ = 0.88 ± 0.04 mol-Einstein⁻¹).
• Rate constants for PAA with •OH (k = 1.3 ± 0.2 × 10⁹ M⁻¹ s⁻¹) and HO2• (kHO ≤ 5 × 10² M⁻¹ s⁻¹) estimated.
• Model accurately predicts PAA decay across varying conditions (PAA/H2O2 concentrations, pH).
• UV/PAA generates lower •OH than UV/H2O2; CH3C(O)OO• is the most abundant carbon-centered radical.

Conclusions:

• The developed kinetic model accurately simulates UV/PAA processes.
• Provides crucial data on reactive species generation and kinetics.
• Enhances understanding of UV/PAA for water disinfection and micropollutant degradation.