Dye effluent treatment using PVDF UF membranes with different properties

Using DMAc as solvent, water as non-solvent, modified poly (vinylidene fluoride) (PVDF) ultrafiltration membranes (PSi, PA, PS) were prepared by precipitation phase inversion, blending with nano-silica (SiO2), polyvinyl alcohol (PVA), and styrene maleic anhydride. The physical-chemical properties and morphology of PVDF membranes were characterized by FT-IR, water contact angle (WCA), swelling index, scanning electron microscopy, atomic force microscopy, etc. Considering reactive black 5 and congo red as the representatives of dye effluent pollutions, the filtration behavior to dye wastewater of four different types of PVDF UF membranes was discussed. Experimental results showed that, compared with original PVDF UF membrane, for three kinds of modified membrane, the first bubble pressure and strength (S) fell off to a certain extent, and the membrane surface roughness increased. Additionally, the cross-sectional macroporous and pure water flux (J) all increased. Especially, owing to the addition of PVA and SiO2, the WCA and the adsorption amount (Q) of PA and PSi membranes were reduced extraordinarily, and flux recovery rate increased obviously. As a result, the hydrophilicity of PVDF membrane was improved significantly. Moreover, the rejection (r) to two dyes was also remained well, which showed a better anti-fouling ability.