Anchoring the TiO2@crumpled graphene oxide core–shell sphere onto electrospun polymer fibrous membrane for the fast separation of multi-component pollutant-oil–water emulsion

Abstract

Membrane separation technology offers the unique advantages in oily wastewater treatment. However, the oily wastewater in petrochemical industry often contains oil emulsions and soluble organic pollutants, which pose great obstacles to membrane materials. Herein, to address the aforementioned challenges, a multifunctional fibrous composite membrane (FCM) was prepared by simple spraying of three-dimensional (3D) TiO2@crumpled graphene oxide (GO) core–shell sphere onto electrospun poly (arylene ether nitrile) (PEN) porous support. In the hierarchical skin layer of composite membrane, the TiO2 nanoparticles were anchored onto 3D crumpled graphene oxide sphere surface assisted by the mussel-inspired dopamine coating, which further triggered the formation of chemical cross-linking networks and hydrogen bond interaction with tannic acid. Such rational design not only ensured the structure stability of the functional layer, but also achieved the extraordinary versatility and high separation efficiency compared the conventional two-dimensional GO stacked lamellar membranes. Due to the super-hydrophilicity/underwater hydrophobic feature, low oil adhesion, and well-regulated water channels, the GO@TiO2/PEN FCM exhibited superior permeance for various surfactant free (4830–5160 L·m−2·h−1) and stabilized oil-in-water emulsions (3142–3514 L·m−2·h−1) while keeping stable rejection rate over 99%. Moreover, the combination of TiO2 nanoparticles and GO endowed the FCM with synergistically enhanced photocatalytic degradation performance for the soluble organics. Under visible light irradiation, the degradation rate of methylene blue (MeB) and crystal violet (CV) could reach 90.8% and 92.5% in 60 min, respectively. Therefore, combination of high permeability and efficient photocatalytic degradation of the soluble organics enable the fibrous composite membrane to realize the fast separation of multi-component pollutant-oil–water emulsion.