Use of TiO photocatalyst supported on residues of polystyrene packaging and its applicability on the removal of food dyes.

This work proposes the use of plastic residues, more specifically polystyrene packaging, to support TiO, used as a photocatalyst in the degradation of erythrosine and Brilliant Blue food dyes. The scanning electron microscopy and Fourier transform infrared spectroscopy analyses exhibited the surface coating and the presence of TiO in the material, respectively. The UV/HO/TiO process was used in the preliminary study, given the high percentage of degradation, operational advantages and greater reductions in peaks related to the aromatic rings when compared to the other processes studied. For the factorial design, the highest efficiency was reached for 150 mg of TiO, a HO concentration of 11.2 mmol L and pH of 5.0. These conditions were used in the degradation kinetics, which was rapid during the first 30 min, with the concentration of dyes in the solution reaching values close to zero after 180 min. Based on the mechanism proposed, the pseudo-first order kinetic model presented the best adjustment to the experimental data. After treatment, the solution presented greater biodegradability and lower toxicity, verified by the lettuce seed germination test (Lactuca sativa). Thus, the UV/HO/TiO process showed great potential in the treatment of industrial effluents contaminated by these food dyes, as well as in reusing discarded polystyrene packaging to support the photocatalyst.