Surface modification of polyacrylonitrile ultrafiltration membranes using amphiphilic Pluronic F127/CaCO3 nanoparticles for oil/water emulsion separation

Abstract

In this work, flat sheet polyacrylonitrile (PAN) based ultrafiltration (UF) membranes were fabricated by blending with amphiphilic copolymer Pluronic F127 (PF127) and inorganic calcium carbonate (CaCO3) nanoparticles by nonsolvent induced phase inversion process which was employed as fouling resistant membranes for the separation of oil-water emulsion mixture. CaCO3 nanoparticle was synthesized by controlled precipitation of saturated carbonate and calcium nitrate aqueous solution and was then confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD) and high-resolution transmission electron microscopy (HR-TEM). The fabricated membranes were characterized by attenuated total reflectance infrared spectroscopy (ATR-FTIR), thermal gravimetric analysis (TGA), mechanical analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM) analysis to study the effect on the addition of PF127 together with varying amount of CaCO3 nanoparticle dosage on the membrane property. The filtration performances of the membranes were evaluated by measuring pure water flux, molecular weight cut off (MWCO), porosity and water content. The membrane hydrophilicity/hydrophobicity was examined through water contact angle measurement and separation efficacy was measured through ultrafiltration of oily feed solution. Membrane properties such as wettability, pure water permeability, mechanical strength, thermal stability, oil removal efficiency of the modified membrane was found to increase high upon addition of 0.75wt% of CaCO3 nanoparticle. Flux recovery was found to elevate from around 63% to 90% after a simple hydraulic wash indicating that the modified hybrid membranes were less susceptible to fouling. The increase in water permeability and antifouling property is ascribed the presence of large number of hydroxyl functional groups coupled with large number of small pores on the modified membrane surface.