Fabrication, tuning and performance analysis of polyacrylonitrile (PAN)-derived microfiltration membranes for bacteria removal from drinking water

Abstract

Removal of bacterial contaminations from water using advanced technologies is one of the essential steps in improving human health. The present study’s aim was to develop high performance microfiltration membranes from polyacrylonitrile (PAN) for bacteria removal from drinking water. The characteristics and performance of membranes were tuned through exploring the variation of prominent fabrication and operating parameters. The findings reveal that increasing PAN concentration in dope and addition of citric acid were successful in tailoring membrane microstructure. Bacteria rejection in modified membranes improved by exhibiting high log removal values (LRV) ranging from 3.92 (99.87%) to 5.57 (99.99%) while permeate fluxes were in the range of 35.83–58.62 L·m−2·h−1. The trends are explained by taking into account the structural characteristics of bacterial strains. Exploring the effect of operating parameters on the performance of membranes revealed that increase in feed concentration from 103 to 107 cfu·ml−1 improved membrane rejection. The largest rejection (5.57) was observed toward Staphylococcus aureus at feed concentration of 107 cfu·ml−1. Similarly, rejection improved upon reducing operating pressure from 3.5 to 1.5 bar. Also, shifting of feed pH to 7.4 and 9.4 enhanced membrane rejection to as high as 4.60 and 5.66 toward E. coli and Staphylococcus aureus, respectively. This was attributed to the zeta potential and isoelectric point values of the membranes and involved strains. Overall, the findings revealed that the developed PAN membranes are more effective in removal of gram-positive strains and their rejection is strongly dependent on the peptidoglycan layer of strains.