Investigation of catalytic performance in benzyl alcohol oxidation reactions and filtration properties of pvdf-metal oxide composite membranes

In this study, preparation and characterization of metal oxide-PVDF composite membranes were conducted. Usability of samples in catalysis and filtration were investigated. The mixture of TiO2, Fe3O4 and MnO2 (Birnessite) with 14% PVDF (in DMF, w/w) was casted in 300 μm ticknes and composite membranes with 0.5%, 1, 2, 4, 6, 8, 10 additives were obtained by phase inversion method. Characterisation of samples were performed by XRD, FT-IR, TG-DTA, SEM and contact angle measurements. From IR results it was observed that α-phases of PVDF disappeared with increasing amount of additives. From SEM images of samples contain 6%, 8, 10 solid, it was concluded that finger-like structures narrowed. Due to catalytic effect of solid, decomposition of polymer fastened with increasing temperature. Decomposition temperatures of raw PVDF, TiO2-P, Fe3O4-P and MnO2-P were 470, 333, 412 and 460 ºC, respectively. Contact angles of raw PVDF and composites were measured as 74.0º, 52.0º, 41.5º and 62.0º respectively. Catalytic activity of samples on benzyl alcohol oxidation was investigated at microwave oven (8 min, 500W) with 1/1 alcohol/peroxide ratio. The highest conversion and benzaldehyde selectivity with TiO2-P, Fe3O4-P and MnO2-P were 93.8%, 99.2, 90.7 and 45.4%, 66.4, 67.8 respectively. Yield of 2-phenylbenzimidazol with MnO2-P was 80% in methanol. Pure water flux (PWF) of raw PVDF, 4% TiO2-P, 2% Fe3O4-P and 4% MnO2-P were 62, 99, 94 and 80 L/m2.h at 2 bar. The best BSA rejection was recorded at 3 and 7.4 pH values. PWF for acrylic acid grafted PVDF membranes decreased while BSA rejection increased.