Abstract: A technique for fabricating a porous TiO₂ photocatalytic degradation screen using direct ink writing (DIW) 3D printing method had been developed. The influence of P25 powder, TiO₂ precursor sol and polyvinyl alcohol (PVA) content on the molding performance of the printing slurry had been clarified. Further studies were conducted on the phase composition, microscopic morphology, band structure, and carrier lifetime of the degradation screen, and its photocatalytic degradation performance and cyclic stability under simulated natural light for tetracycline hydrochloride (TC) were determined. The results showed that the TiO₂ precursor sol can disperse P25 particles and stabilize the slurry, while the addition of PVA further improves the rheological properties of the slurry. When 9 g of P25 powder is mixed with 10 mL of TiO₂ precursor slurry and 1 mL of 7% PVA solution, the printing slurry with the best molding performance is obtained. The degradable screen structure made by the prepared material is intact, without collapse and crack. After thermal treatment, the TiO₂ precursor dispersion is converted into small-sized TiO₂ particles, which fill the voids between P25 particles and enhance the mechanical strength. Meanwhile, PVA serves as a pore former to greatly enrich the pore structure of the degradable screen. TiO₂ photocatalytic degradation screen exhibits excellent photocatalytic performance and cyclic stability towards TC, with a degradation rate of 98.4% within 140 minutes and a degradation rate of 96.0% after five cycles.

Key words: 3D printing, photocatalysis, TiO₂, tetracycline hydrochloride