Biomimetic Modification of Super-wetting Electrospun Poly(vinylidene fluoride) Porous Fibers with Organic Dyes and Heavy Metal Ions Adsorption, Oil/Water Separation, and Sterilization Performances Toward Wastewater Treatment

Polymeric membranes with the integration of various functional performances toward wastewater treatment are urgently required. However, most of the polymeric membranes only exhibit a single function of highly efficiently removing one kind of pollutants. In this work, a biomimetic modification method was introduced to tailor the chemical and topological structure of the porous poly(vinylidene fluoride) (PVDF) fibers prepared by electrospinning. The polydopamine (PDA) nanoparticles were homogeneously introduced onto the surface of PVDF porous fibers via precisely tailoring the concentration of dopamine, which endowed the fibers with more polar groups and bigger roughness but did not destroy the crystalline structures. The fibrous membranes exhibited switchable superhydrophilicity and superlipophilicity characteristics, excellent adsorption abilities toward organic dyes, heavy metal ions and oils. The highest adsorption capacities achieved 917.4 mg/g toward methylene blue (MB), 42.6 mg/g toward Cr(VI) and 74.6 g/g toward silicone oil, respectively. Specifically, the membrane could rapidly remove the trace MB when water flowed through the membrane. The membrane also exhibited excellent sterilization performances, and the bacterial eliminating rate achieved 99.9% for the E. coli and S. aureus. The excellent light-to-heat conversion ability endowed the membrane with the self-heating ability, furtherly intensifying the wastewater treatment efficiency. This work confirms that the PDA nanoparticles-decorated PVDF porous fibers might be the new generation adsorbents used in wastewater treatment.