Hierarchical poly(vinylidene fluoride)/active carbon composite membrane with self-confining functional carbon nanotube layer for intractable wastewater remediation

Abstract The efficient removal of trace micro pollutants and heavy metals from wastewater has been deemed as major challenge in the field of water treatment. Membrane composites have shown promises for the removal of these contaminants via green chemistry principles (i.e. membrane filtration). However, membrane composites normally lack appropriate surface porosity which hinders their performance, and it oftentimes causes membrane fouling. In this work, in order to ensure simultaneous removal of trace micro pollutants and heavy metals, a multi-functional active carbon inlayed poly(vinylidene fluoride) (PVDF) composite membrane with antifouling surface of polyacryloyl hydrazide (PAH)-grafted-carbon nanotubes (CNTs) layer is fabricated for the cross-flowing separation of oil/water emulsion, and heavy metals removal. The as-prepared PVDF-membrane composite with highly porous structure is integrated with powdered activated carbon (PAC) inlayed via the delayed liquid-liquid de-mixing process. The system shows high dynamic adsorption capacity towards the removal of toxic micro pollutants such as nitro-phenol, sulfamerazine and bisphenol A. In addition, micro/nano-hierarchical surface is constructed on the PVDF membrane via phase inversion. This enables successful anchorage of PAH-grafted-CNTs as antifouling layer on the surface of the PVDF-membrane. The reductive hydrophilic PAH brush on CNTs adsorbs different kinds of trace heavy metals (i.e. Cu2+, Ni+, and Cr3+) through reduction process. The PAH-grafted-CNTs also endows the composite membrane with excellent antifouling towards proteins.