Electrospun polyetherimide/zeolitic imidazolate framework nanofibrous membranes for enhanced air filtration performance under high temperature and high humidity conditions

Efficient filtration of particulate matter (PM) is the major goal for various air cleaning technologies. However, most existing air filters are conducted at room temperature with a relative humidity (RH) of around 45%, ignoring the fact that many operate under high temperature and RH above 90%. Herein, we report the successful fabrication of a polyetherimide (PEI)/zeolitic imidazolate framework-67 (PEI/ZIF-67) nanofibrous membranes using electrospinning technology, which showed steady and high efficiency PM filtration performance under a high temperature of 200 °C and RH of 90%. Compared with pure PEI nanofibrous membranes, the resultant nanofibrous membranes containing 2 wt% of ZIF-67 showed an increase of 112% and 109% in removal efficiency of PM 2.5 and PM 10, respectively, which are attributed to synergistic effects of enhanced surface roughness, strengthened electrostatic interaction and small pore size by the introduction of the ZIF-67. More importantly, after operating under a high RH of 90% over 70 h, the removal efficiency of such PEI/ZIF-67 nanofibrous membranes remained almost unchanged. Density functional theory calculations suggested that the ZIF could efficiently reduce water adsorption and thereby avoid the PEI being damaged by water. Such a finding demonstrated that the ZIFs should be promising candidates for designing highly stable nanofibrous membranes under extremely high RH and high temperature conditions.