Incorporation of Silver-Doped Graphene Oxide Quantum Dots in Polyvinylidene Fluoride Membrane for Verapamil Removal

Verapamil hydrochloride, a calcium channel-blocking agent, is detectable in receiving water bodies and affects the well-being of aquatic organisms. Membrane filtration could be effective in removing such pharmaceutical contaminants. However, limited studies have employed commercial membranes, such as polyvinylidene fluoride (PVDF), in removing verapamil from water sources, owing to their low solution fluxes, poor antibacterial properties, and high surface hydrophobicity. Efforts are needed to create the PVDF membrane suitable for removing verapamil from water sources. In this study, PVDF composite membranes incorporated with from 0 to 0.10 wt% silver-doped graphene oxide quantum dots (Ag-GOQD) were evaluated in terms of their morphological structures, elemental composition, surface roughness, hydrophilicity, verapamil rejection capability, anti-fouling, and antibacterial capabilities. The pure PVDF membrane showed the lowest verapamil rejection (73.66 +/- 2.45%), highest surface roughness (mean surface roughness, Sa = 123.80 nm), and least hydrophilic membrane surface (contact angle = 79.06 +/- 4.53 degrees) when compared to other membranes incorporated with nanocomposites. However, the membrane incorporated with 0.10 wt% Ag-GOQD showed the smoothest and the most hydrophilic membrane surface (Sa = 13.10 nm and contact angle = 53.60 +/- 4.75 degrees, respectively), associated with the highest verapamil rejection (96.04 +/- 1.82%). A clear inhibition zone was spotted in the agar plate containing the membrane incorporated with Ag-GOQD, showing the antibacterial capability of the membrane. The overall improvement in morphological structures, surface smoothness, surface hydrophilicities, permeabilities, verapamil rejection abilities, and anti-fouling and antibacterial capabilities indicated a great potential to incorporate Ag-GOQD in PVDF membrane fabrication.