Towards the Configuration of a Photoelectrocatalytic Reactor: Part 1—Determination of Photoelectrode Geometry and Optical Thickness by a Numerical Approach

Photoelectrocatalysis has been highlighted as a tertiary wastewater treatment in the textile industry due to its high dye mineralisation capacity. However, design improvements are necessary to overcome photo-reactors limitations. The present work proposes a preliminary configuration of a photoelectrocatalytic reactor to degrade Reactive Red 239 (RR239) textile dye, using computational fluid dynamics (CFD) to analyse the mass transfer rate, radiation intensity loss ([Formula: see text]), and its effect on kinetics degradation, over a photoelectrode based on a [Formula: see text] nanotube. A study to increase the space-time yield (STY) was carried out through mass transfer rate and kinetic analysis, varying the optical thickness ([Formula: see text]) between the radiation entrance and the photocatalytic surface, photoelectrode geometry, inlet flow rate, and the surface radiation intensity. The [Formula: see text] was determined using a 1D Beer–Lambert-based model, and an extinction coefficient experimentally determined by UV-Vis spectroscopy. The results show that in RR239 solutions below concentrations of 6 mg/L, a woven mesh photoelectrode and an optimal optical thickness [Formula: see text] of 1 cm is enough to keep the [Formula: see text] below 15% and maximise the mass transfer and the STY in around 110 g/m [Formula: see text]-day.