Effect of low pressure plasma surface modification on filtration performance of chitosan nanofibrous respiratory filter

Low pressure drop is highly desirable for respiratory filters. Surface activation plays an important role in enhancing the filtration performance of respiratory filters. In this study, a three-layer composite respiratory filter was developed by using the combination of polypropylene (PP) nonwoven layers and chitosan nanofibres (CSNF) using electrospinning. To study the impact of surface activation on filtration performance, the outer surface of all the samples were modified by using low pressure plasma treatment. Filtration performance testing was conducted to determine the filtration efficiency (%), pressure drop (Pa), and quality factor (Q) before and after the surface treatment. The maximum values of filtration efficiency and quality factor achieved were 99.99% and 0.068 respectively. The lowest value of the pressure drop was 16.12 Pa. All the low pressure plasma treated samples showed higher filtration efficiency and quality factor compared to untreated samples due to more effective capturing mechanism. However, pressure drop results indicated no significant difference. Furthermore, the decay of plasma treatment impact was analysed by using the drop shape analysis method to measure the water contact angle on the surface of the samples. Results showed a gradual decrease in surface modification impact and surface of treated samples changed from hydrophilic to hydrophobic after 60 days.

Keywords: Filtration performance, Surface activation, Low pressure plasma, Nanofibres, Respiratory filter