Modeling the UV/H₂O₂ oxidation of phenolic compounds in a continuous-flow reactor with reflective walls

Continuous-flow advanced oxidation processes (AOPs) are commonly used for the destruction of persistent trace organics that survive conventional wastewater treatment processes. The UV/H₂O₂ process is one of the most widely used AOPs. A common configuration for this process consists of a concentric lamp located at the center of a pipe. In this work, two novel flow-through UV reactors with concentric low-pressure lamps and UV reflective surfaces are used to investigate the destruction of trace organics. A kinetic/transport model was developed to simulate the process. The model includes elementary reactions of the UV/H₂O₂ system, direct UV photolysis of the target, and reactions of the target with hydroxyl radicals, H₂O₂ and reaction intermediates. The model incorporates UV light reflection from the reactor walls, as well as the hydrodynamics of the annular flow. The model accurately predicts the destruction of the target compounds in a wide range of experimental conditions. Experimental and theoretical results demonstrate that wall reflectivity provides a significant enhancement of the rate of conversion of the target in high transmittance solutions as expected.