Direct dye wastewater photocatalysis using immobilized titanium dioxide on fixed substrate

Photocatalysis is a promising technology that can be applied to the dyeing of wastewater. During the process of photocatalysis, titanium dioxide (TiO₂) is often used as a catalyst due to its low cost and broad availability. However, the use of TiO₂ powders can result in certain difficulties associated with separating TiO₂ from the treated wastewater. Therefore, immobilization of TiO₂ on two different substrates, including glass and iron beads, was studied in this body of research work. The composite materials were prepared by spraying liquid dispersion onto the substrates, and the materials were then calcined at different temperatures (600-750 °C). At 700 °C calcination temperature, SEM and EDS analyses revealed that the particles of TiO₂ were evenly distributed on the substrates. Importantly, the deposited TiO₂ particles are mixed-phase anatase and rutile structures, both of which are considered beneficial to the photocatalysis process. Ultimately, a degree of direct dye photodegradation efficiency of 64.0 % at 4 h was achieved from the composite materials that were calcined at 700 °C. The degradation efficiency of the reused catalyst was not significantly changed in the second cycle revealing their capability in reusable. The stability of immobilized TiO₂ onto the fixed substrates was still high after the second use.