| Abstrakt: |
The ubiquity of per- and poly-fluoroalkyl substances (PFASs) in production and usage, coupled with their enduring presence and mobility within the environment, has underscored significant human exposure. Membrane filtration and adsorption processes stand as principal and effective means for PFAS elimination from water, each contributing to distinct separation attributes. While thin-film composite (TFC) nanofiltration (NF) membranes achieve satisfactory PFAS removal (<90%), rejected PFAS in the concentrated stream necessitates supplementary separation measures. This study presents the development of adsorptive thin-film nanocomposite (TFN) NF membranes, functionalized with submicron (∼500 nm) activated carbon (SFAC), to enhance perfluorooctanesulfonic acid (PFOS) removal via adsorption during water filtration. The NF membrane was fabricated on a poly(ether sulfone) support layer with a polyamide (PA) selective layer functionalized by immobilization of SFAC inside the PA via interfacial polymerization (IP). The effect of SFAC on the piperazine and trimesoyl chloride transport during the IP process and consequently on the PA attributes encompassing morphology and chemistry, and performance (permeability and rejection) was investigated. The resulting SFAC-TFN membranes with optimal loading showcased a remarkable PFOS removal efficiency of 94%, where over 80% was attributed to adsorption. Furthermore, these membranes exhibited heightened permeability while maintaining marginal salt rejection reduction in comparison to bare TFC membranes. Remarkably, SFAC-TFN membranes exhibited sustained PFOS removal even after four regeneration cycles, employing a 50% ethanol/water solution for regeneration. The findings offer insights into the synergy of adsorption and separation mechanisms, indicating promising avenues for advanced PFAS treatment strategies. |
