Photocatalytic Performance of 3D-Printed Triply Periodic Minimal Surface Photocatalytic Reactors

To overcome poor catalyst recovery and inefficient mass transfer in photocatalytic water treatment, this study presents novel Triply Periodic Minimal Surface (TPMS) photocatalytic reactors (PCRs) fabricated via Stereolithography (SLA) 3D printing. Five TiO2-loaded reactors (Fischer-Radin-Dunn (FRD), Neovius (N), Diamond (D), I-graph Wrapped Package (IWP), Gyroid (G)) with hierarchical porosity were designed. Using methylene blue (MB) as the target pollutant, the photocatalytic degradation performance of TPMS-PCRs is evaluated and Computational Fluid Dynamics (CFD) hydrodynamic simulations are conducted to analyze their flow characteristics under both horizontal and rotational flow fields. The catalytic efficiency of TPMS reactors is influenced not only by pore characteristics, specific surface area, and inter-pore connectivity, but also by the flow velocities on both the reactor surface and within its internal channels. The FRD-type TPMS-PCR loaded with 2.5 wt% TiO2 exhibited optimal photocatalytic performance, achieving 95.36% degradation efficiency under rotational flow within 2.5 h, compared to 88.2% under horizontal flow. Remarkably, after five degradation cycles, its efficiency further improved to 96.7%, demonstrating its excellent stability. The rotational flow field enhanced the average flow velocity by approximately sixfold compared to horizontal flow, with the D-type reactor reaching a maximum surface velocity of 5.3 × 10−2 m/s.