Controllable fabrication of photocatalytic TiO2 brookite thin film by 3D-printing approach for dyes decomposition

An immobilized photocatalytic system is being considered as an advantage for wastewater treatment. The stability and durability of photocatalytic materials in film form strongly depend on both supported materials and immobilization techniques. In this work, the composite of a styrene-acrylate (DC668) polymeric binder and the TiO2 brookite spherical nanoparticles (NPs) was immobilized on the surface of the glass substrate by direct-inkwriting technique using a 3D printer. Physicochemical and photocatalytic properties were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy, respectively. Rose bengal (RB) was used as the target pollutant to investigate the photocatalytic behavior of the obtained TiO2/DC668 composite thin film which was evaluated by UV-VIS absorption spectra. We found that an amount of less than 10% of the industrial DC668 emulsion has significantly improved the dispersion of TiO2 NPs in the polymeric matrix as well as the adhesion of 3D-printed TiO2 thin film to the glass surface. After UV-A light exposure for 300 min, the decomposition rate of RB over TiO2 film was 0.029 min-1 corresponding to the nearly complete decolourization. The reuse tests show that the thin-film photocatalyst was remarkably stable. Its high activity can be maintained after four uses with the RB dyes photodegradation efficiency of 92%. The photo-catalyzing capacity of the thin films with immobilized TiO2 NPs was slightly lower than that of only bare TiO2 NPs, but the thin film can be efficiently reused for more cycles without any further separation. Thereby, the 3D-printed TiO2 brookite thin-film photocatalysts provide the potential for application in large-scale wastewater treatment.

Automated summary

The preparation and characterization of immobilized TiO2 photocatalytic thin films have shown high stability and reusability in wastewater treatment, providing potential applications for water pollution control.