Enhancing filter efficiency of polyimide/polyethersulfone nanofiber membranes via novel treatments of high pressure processing, thermocompression, atmospheric plasma, and corona discharge

Abstract

In this study, novel post-treatments contained of high pressure processing (HPP), thermocompression, atmospheric plasma, and corona discharge were used to progress the filter quality of polyimide/polyethersulfone (PI/PES) nanofiber membranes in the conditions of 50/50 % PI/PES, 0.15 ml/hr flow rate, 22.5 kV, and 20 min. The filter quality of nanofiber membrane did not get progress after HPP and thermocompression treatments, so high temperature and pressure did not improve the filter quality. Otherwise, atmospheric plasma destroyed the morphology of fiber surface, caused loss of filter efficiency and filter quality. However, corona discharge treatment presented different result with the above three treatments, and the filter efficiency and filter quality of the fiber membrane was improved after corona discharge treatment. Furthermore, factor influence order was ranged as operational voltage, discharge time, and discharge distance from result of filter quality on comparison of S/N value and level difference via Taguchi method. The application of corona discharge resulted in fiber acquired surface electric potential of 0.315 ± 0.56 kV at the optimized conditions of operational voltage (25 kV), discharge distance (7 cm), and discharge time (60 min), and filter efficiency of fiber enhanced from 95.66 ± 0.96 % to 98.70 ± 0.36 %. Further, the optimized PI/PES nanofiber membranes with corona discharge not only had a remarkable filter quality (2.214 Pa−1) but also maintained an effective filtration efficiency of ultra-fine particles (98.70 %) and a low pressure loss of 1.961 Pa for creating a promising filter of air purification and N95 Masks of USA NIOSH Standard.