Dye and bacteria photodegradations with anatase-loaded microporous poly(vinylidene fluoride) membranes

Abstract

Non-skinned microporous membranes containing anatase particles were fabricated without anatase loss with the dry cast technique. The membranes were characterized by scanning electron microscopy, X-ray diffraction (XRD), infrared spectroscopy, thermal gravimetry analysis and contact angle measurements. Anatase particles were fairly well distributed in the crystallized-PVDF microporous matrix, mainly as aggregates. The membrane porosity, as well as their nitrogen and water permeabilities, reached a maximum at 0.5 TiO₂/PVDF weight ratio. The anatase-loaded PVDF membranes were successfully used in the dye and bacteria photodegradations catalyzed by anatase particles. The dye sorption and the photodegradation kinetics with the membrane of 0.5 TiO₂/PVDF weight ratio obeyed the Freundlich and the first-order laws, respectively. In the photodegradation of a dye mixture, the better sorbed dye was preferentially photodegraded, suggesting the key role of dye sorption in the photodegradation mechanism. The technical feasibility of the supported photocatalyst in a continuous discoloration of a dye solution was shown in runs of a flat-type reactor under a black-light lamp or direct solar light.