CNT functionalized ZIF-8 impregnated poly(vinylidene fluoride-co-hexafluoropropylene) mixed matrix membranes for antibiotics removal from pharmaceutical industry wastewater by vacuum membrane distillation

Abstract We report CNT functionalized ZIF8 (CNT@ZIF8) impregnated poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) mixed matrix membranes to remove antibiotics from pharmaceutical industry wastewater by vacuum membrane distillation. Different morphological and spectral techniques were used for structural elucidation of ZIF8 and CNT@ZIF8 and membrane performance in terms of flux and removal efficiency. Embedded ZIF8 nanoparticles in CNT retained their crystal structure in the CNT@ZIF8 composite. In the membrane matrix, impregnation of both ZIF8 and CNT@ZIF8 increased the membrane mean pore size and porosity, responsible for improved flux. In addition, rougher surface for mixed matrix membranes enhanced the hydrophobicity of membranes, and thus removal efficiency of select antibiotics used in this study. Among the fabricated membranes, the M-ZC (18% PVDF-co-HFP/0.5% CNT@ZIF8) membrane was most suitable with >99.4% removal efficiency for all the antibiotics at 60 °C feed temperature. The recorded flux for M-ZC was 11.1, 10.9, 12.2, and 11.6 kg m−2 h−1 for tetracycline, doxycycline, norfloxacin, and ciprofloxacin, respectively. The fabricated mixed matrix membranes revealed exceptional thermal stability up to 400 °C. The study showed that the fabricated membranes have great potential to treat wastewater containing antibiotics.