Synthesis of hybrid hydrophobic composite air filtration membranes for antibacterial activity and chemical detoxification with high particulate filtration efficiency (PFE)

• Nanofiber filters incorporated with Al2O3 nanoparticles were prepared for air filtration.
• The filters are antibacterial, detoxifying and with excellent particle filtration efficiency.
• Detoxification efficiency of filter to paraoxon increased with higher Al2O3 concentrations.
• Particle filtration efficiency of filters also increased with higher Al2O3 concentrations.
• Resistance of filters only increased marginally with higher Al2O3 concentrations.

Hybrid hydrophobic composite PVDF–Ag–Al2O3 nanofibrous air filtration membranes are synthesized by the electrospinning method with different concentrations of Al2O3 and fixed concentration of Ag to study their antibacterial, particulate filtration efficiencies, and their detoxification ability. All the membranes were characterized for their physical and chemical properties before being tested. It was also found that at Al2O3 concentrations higher than 8%, nanofibers could not be formed by the pure blending and electrospinning technique. The antibacterial activity of the membranes proved that silver incorporation provided suitable disinfection with greater than 99.5% antibacterial efficiency for all membranes. The antibacterial efficiency of the membranes was maintained even as the concentration of Al2O3 was increased. The hydrolysis of paraoxon, a nerve agent simulant, for the prepared membranes was also studied. The removal of paraoxon was found to increase as the loaded concentration of Al2O3 in the membrane increased. The particulate filtration efficiency of the prepared membranes was tested using particles of diameter 0.36 μm. Compared to the nascent PVDF nanofiber membranes with particle filtration efficiency of 94%, the Ag and Al2O3 loaded membranes all had a higher particle filtration efficiency. Interestingly, it was found that as the concentration of Al2O3 loaded in the membranes increased so did the particle filtration efficiency. Membrane characterization data revealed that as the concentration of the Al2O3 was increased, the average pore size of the membrane was reduced and the thickness of the filter mat increased. This would explain the higher retention of the particles by these filters. Correspondingly, the resistance of the filters also increased as more Al2O3 was loaded in the nanofiber membranes. The synthesized nanofibrous membranes have the potential to be used as 3 in 1 highly efficient air filters.

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