Surface distribution of phenol photodegradation in Rotating Disc Reactors

Westgate, Ewan and Johnson, Dominic and Aiouache, Farid (2026) Surface distribution of phenol photodegradation in Rotating Disc Reactors. Chemical Engineering Research and Design. ISSN 0263-8762 (In Press)

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Abstract

Photocatalytic rotating disc reactors offer enhanced illuminated surface area but are constrained by thin reactive films, laminar flow, mass-transfer limitations, and limited throughput. This study investigates these limitations and proposes a hydrodynamic approach to improve reactor performance and scalability while providing insights relevant to future scale-up. A three-dimensional CFD model based on the level-set method, coupled with ray tracing, was developed to simulate two-phase air–water flow and incorporate surface reaction kinetics. Simulations were validated against laboratory experiments using a custom-fabricated TiO₂-coated rotating disc reactor. Surface modification via sandblasting increased micro-roughness, improving coating adhesion, while dip coating produced uniform catalyst films (1.3 μm thickness, 0.55 mg cm⁻² loading) with reproducible linear growth upon successive deposition. Hydrodynamic analysis revealed radially non-uniform performance, with increasing tangential velocity and shear towards the disc periphery enhancing mass transfer and catalytic activity. Phenol conversion increased from 8.71% at 60 rpm to 11.42% at 240 rpm, and further reducing liquid immersion improved conversion to 17.42%. The achieved photocatalytic space–time yield reached 93.6 mmol day⁻¹ kW⁻¹ and was primarily limited by mass transfer. These results highlight the importance of hydrodynamic control in improving photocatalytic efficiency and provide guidance for the future development and scale-up of rotating disc reactors.