Bromide-Catalyzed Ozonation for Trace Urea Removal: pH-Dependent Kinetics, Catalytic Mechanisms, and Implications for Ultrapure Water Production

High Resolution Image Download MS PowerPoint Slide Urea is a common organic compound present in natural and reclaimed waters, which poses challenges for ultrapure water (UPW) production because conventional treatment processes are insufficient to achieve the required low concentrations. This study systematically investigated the pH-dependent kinetics, mechanistic pathways, and byproduct formation during treatment with a bromide-catalyzed ozonation (O 3 /Br – ) process for urea (0.5–1 μM) removal. In buffered systems, optimal performance was achieved at an [O 3 ] 0:[Br – ] 0 molar ratio of 1:1–1.5:1, with complete urea removal within 20–30 min at 200/200 μM dosing. To simulate practical conditions, unbuffered reclaimed reverse osmosis (RO) permeate (initial pH of 3.0–6.0) was evaluated. Pre-adjustment to mildly acidic conditions (pH ≈3.5) maintained ozone stability, minimized pH drift, an…