Functionalization of polyamide microfiltration membranes by supercritical solvent impregnation

Abstract

The study reports the application of supercritical solvent impregnation to deliver antibacterial substance thymol to the defined polymeric structure of commercial polyamide microfiltration membranes. The process performed at a temperature of 40 °C and pressures of 10, 15, and 20 MPa was characterized by the fast impregnation in the first 30 min with thymol loadings up to 29 wt%. The maximal achieved thymol loading in the process was around 42 wt%, regardless the pressure. The scanning electron and ion microscopy analyses revealed that the membranes’ microstructure was preserved with a thymol content of 20 wt%, while a more prominent swelling effect was observed in samples with 35 wt% of thymol. The cross-flow filtration tests showed that the impregnation process did not harm the membranes’ functionality in samples with 20 wt% of thymol. These membranes exhibited strong anti-biofilm activity, and were less prone to the blockage with bacteria in comparison to neat membranes.