Application of metal oxides thin-film catalysts in structured catalytic ozonation reactor for dye and by-product detoxification.

More than ten thousand cubic meters of highly polluted textile wastewater are discharged into the environment daily worldwide, highlighting the urgent need for effective wastewater treatment solutions. This study addresses this challenge by introducing a novel ozone system based on plasma-prepared catalysts for textile wastewater treatment. Metal oxide thin-films were deposited onto knitted Kanthal mesh by plasma-enhanced chemical vapor deposition (PECVD), creating a stable 3D catalytic material for heterogeneous catalysis. Kinetic analysis of the removal of textile dye, Reactive Black 5, revealed the effectiveness of cobalt and iron oxides as catalysts, with kinetic constants of (2.46 ± 0.03) × 10^-3 1/s and (2.93 ± 0.05) × 10^-3 1/s, respectively, surpassing the kinetic constant of classical ozonation, which was only (1.66 ± 0.05) × 10^-3 1/s. These thin-film catalysts exhibited superactivity, particularly in alkaline pH conditions, but remained active across a range of pH levels, including acidic and neutral environments. Structural and compositional analysis conducted through X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy energy-dispersive X-ray spectroscopy (SEM EDX) confirmed the stable and active nature of the cobalt oxide (Co₃O₄ spinel form) and iron oxide (Fe₂O₃) catalytic films. Optimization ensured a pollutant-to-ozone ratio below 1:10 using only 0.3 mg O₃/L, confirming catalytic efficiency with minimal oxidant input.