Use of Ca–alginate as a novel support for TiO₂ immobilization in methylene blue decolorisation

This study provides a preliminary contribution to the development of an industrial process for the UV/TiO₂ water treatment by introducing a novel support for TiO₂ immobilization. For the following study, Methylene Blue (MB) was chosen as the model dye to evaluate this novel immobilization system. The results showed that TiO₂ immobilized in a Ca–alginate bead retained its photoactivity during all of the experiments and the TiO₂-gel beads presented good stability in water for maintaining its shape after several uses. When a proportion of 10% (v/v) of these beads was used, the configuration system demonstrated an improved mass transfer and consequently enhanced degradation efficiency. Experiments were also performed using ‘recycled’ beads. The results showed an increase in the degradation efficiency when the beads were reused, with an eventual ‘self-destructive’ effect. These studies showed great promise regarding the recyclable reagents with a reduction in waste at no greater cost or reduction in efficiency. Therefore, the potential of TiO₂-gel beads as a simple and environmentally friendly catalyst for continuous use was developed.