Abstract
In this work, we investigated the preparation of porous titanium dioxide (TiO2) coatings via plasma electrolytic oxidation (PEO) for its use as a photocatalytic surface in water treatment. A fractional factorial design (FFD) was used to optimize various coating parameters such as electrolyte composition, electrical parameters, and treatment time. The impact of PEO parameters on the wettability, crystalline phase, and surface morphology of coatings was also investigated. The optimal PEO parameters were found to be the electrolyte composition (5 g.L−1 Na3PO4 and 4 g.L−1 KOH), electrical current density (6 A.dm−2), (80%) duty cycle, and (1000 Hz) frequency, as well as (10 min) treatment time. The photocatalytic behavior of the optimal coating was assessed under different experimental conditions, such as pollutant concentration, light intensity, and pH. The photocatalytic mechanism was proposed based on the results of Tauc plot, Mott–Schottky analysis, and scavenging experiments. Additionally, the efficiency of photocatalytic activation of peroxymonosulfate (PMS) by a PEO-treated TiO2 coating was evaluated for the first time. A synergistic effect between PMS and TiO2 was observed, and the total organic carbon (TOC) test showed notable mineralization at low [PMS]. The results suggest that this simple, environmentally-friendly, low-cost, and robust process is a promising coating method for the field of water treatment.
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