To enhance the activity and dispersibility of nano zero-valent iron particles (NZVI), PVDF center dot Al2O3 film is innovatively modified by an environmentally friendly reagent, polydopamine (PDA), via one-step grafting with an in situ simultaneous self-polymerization of PDA onto PVDF center dot Al2O3 film surface before immobilization of NZVI in the PVDF center dot Al2O3 film. The resultant PDA/PVDF center dot Al2O3 NZVI (PPAN) hybrid exhibits high activity and reusability for metronidazole (MNZ) removal. Investigation on mechanical strength of PDA/PVDF center dot Al2O3 film indicates that the tensile strengh and modulus of elasticity of the film are significantly improved. Compared with unimmobilized NZVI, the removal efficiency of MNZ by PPAN-2 hybrid synthesized under optimized conditions is increased by 40.2%. Such excellent performance can be attributed to -OH and/or -NH groups in PDA polymer structure that facilitate the interaction and coordination between the precursor of NZVI and functional groups coating on PVDF center dot Al2O3 film, resulting in the enhanced loading amount, dispersion, and activity of NZVI on PPAN-2 hybrid. Kinetics of MNZ removal by PPAN-2 are found to follow a two-parameter pseudo-first-order model. The presence of humic acid (HA) slightly inhibits the activity of PPAN-2 for MNZ removal. This research suggests that PPAN hybrid may be a promising functional composite for antibiotic wastewater treatment. (C) 2017 Elsevier B.V. All rights reserved.