A simple surface modification method to prepare versatile PVDF electrospun nanofibrous felts for separation, sterilization and degradation

The discharge of oily effluents from industrial production and crude oil spills at sea result in significant water pollution, posing a major danger to the environment and human health. Due to the tiny droplet size, emulsion separation is a difficult task in the separation and purification of oily wastewater. Polydopamine (PDA) and TiO2 nanoparticles were coated on the surface of polyvinylidene fluoride (PVDF) electrospun nanofibrous to increase surface roughness, and then the low surface energy substance octadecylamine (ODA) was grafted. As a result, a superhydrophobic PVDF@PDA/TiO2@ODA nanofibrous felts with a water contact angle of 168.1° has been developed. Because of their three-dimensional porous structure, the nanofibrous felts have a porosity of up to 72.9 %. The tensile strength of a series of reinforced PVDF@PDA/TiO2@ODA nanofibrous felts reaches 30.06 MPa, which is useful for maintaining the stability of the nanofibrous felts during the pressure separation. The oil and water in the emulsion are entirely separated due to the selective permeability induced by the strong superhydrophobic and superlipophilic properties. The separation efficiency of over 99 % and flow flux of above 1100 L·m−2·h−1 are achieved. The performance of the nanofibrous felts in inhibiting bacterial growth was then investigated, and it is found that a significant inhibition circle appeared in the flat dish diffusion method, with a bacteriostasis rate exceeding 99 %. This result demonstrates that PVDF@PDA/TiO2@ODA nanofibrous felts have excellent antimicrobial properties. Finally, UV–vis absorption spectroscopy was employed to demonstrate the good catalytic degradation of organic dyes by PVDF@PDA/TiO2@ODA nanofibrous felts. PVDF@PDA/TiO2@ODA nanofibrous felts have a variety of applications in the deep separation and purification of oily wastewater due to these characteristics.