Supercritical Phase Inversion to Produce Photocatalytic Active PVDF-coHFP_TiO[sub.2] Composites for the Degradation of Sudan Blue II Dye

TiO[sub.2]-loaded poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-coHFP) membranes were produced by supercritical CO[sub.2]-assisted phase inversion. Three different TiO[sub.2] loadings were tested: 10, 20, and 30 wt% with respect to the polymer. Increasing the TiO[sub.2] amount from 10 wt% to 20 wt% in the starting solution, the transition from leafy-like to leafy-cellular morphology was observed in the section of the membrane. When 30 wt% TiO[sub.2] was used, the entire membrane section showed agglomerates of TiO[sub.2] nanoparticles. These polymeric membranes were tested to remove Sudan Blue II (SB) dye from aqueous solutions. The adsorption/photocatalytic processes revealed that membrane morphology and TiO[sub.2] cluster size were the parameters that mainly affected the dye removal efficiency. Moreover, after five cycles of exposure of these membranes to UV light, SB removal was higher than 85%.