Eco-friendly fabrication of porphyrin@hyperbranched polyamide-amine@phytic acid/PVDF membrane for superior oil-water separation and dye degradation

Abstract

The treatment of oily wastewater containing water-soluble dyes has drawn attention and become a thorny issue. Aiming at removing oil droplets and dyes from wastewater, it is reported in this work the design of polyelectrolyte deposited dual functional membrane with superior separation and degradation capabilities. The hyperbranched polyamide-amine (HPAMAM) was combined with tetra (4-carboxyphenyl) porphyrin (TCPP) and phytic acid (PA) through electrostatic interaction to form an eco-friendly polyelectrolyte complex by one-step self-assembly method. Relying on affluent amine group and unique cavity structure as well as wide range of delocalized π-electron systems, TCPP@HPAMAM@PA possesses robust water binding ability and intense absorption in the visible region, endowing PVDF membrane with superhydrophilicity/underwater superoleophobicity, oil resistance and superior photocatalytic degradation properties. The dual functional TCPP@HPAMAM@PA/PVDF membranes can realize superb removal of oil droplets (oil rejection > 99 %) at high flux recovery rate with several cycles. Furthermore, the degradation efficiency of rhodamine B (RhB) and Methyl blue (MB) reaches 93 % and 96 % respectively, showing standout photocatalytic degradation performance. A facile and low-energy strategy for the modification of commercial PVDF membranes is proposed, which is not only consistent with the concept of green chemistry but also has a broad application in the separation of complex oily wastewater systems.