PVDF/Polypyrrole Composite Ultrafiltration Membrane with Enhanced Hydrophilicity, Permeability, and Antifouling Properties for Efficient Crude Oil Wastewater Separation

The treatment of oily wastewater poses a significant environmental challenge, creating a demand for advanced separation technologies. Membrane technologies, especially ultrafiltration (UF), offer a promising solution. A novel composite polyvinylidene fluoride (PVDF) and polypyrrole (PPy) membrane was created via an in situ polymerization method, which enhances the membrane's functionality by combining the chemical stability of PVDF with the outstanding properties of PPy, through a simple two-step process that decreases manufacturing costs. The PPy content in the PVDF matrix varies from 0 to 1.5 wt%. The membranes were analyzed for their structure, morphology, hydrophilicity, porosity, mechanical strength, flux, oil rejection, and antifouling performance. Fourier-transform infrared spectroscopy (FTIR) confirmed the successful integration of PPy, which increased hydrophilicity; the contact angle dropped from 68° for pure PVDF to 55.6° at a 1.5% PPy concentration. Scanning electron microscopy (SEM) images showed an evident increase in surface porosity and macrovoid formation; calculated porosity increased from 59.5% to 79.9%, and the hydraulic pore size increased from 2.8 nm to 28.5 nm with 1.5% PPy. Although porosity improved, mechanical strength decreased due to the formation of voids. The enhancement in hydrophilicity and porosity resulted in improved flux recovery (FR), with the PP-1 membrane achieving 93% FR and 93% fouling resistance (Rt), indicating an optimal balance for practical use. These modified membranes successfully reduce fouling, making them easier to clean in oil-water separation applications. PP-1 showed only a reduction in flux but maintained an oil rejection rate over 99%, demonstrating high stability. This combination of PVDF's durability and PPy's functionality makes a cost-effective, high-performance membrane that transforms oil/water separation processes for sustainable water security.