Enhancement of Antifouling and Antibacterial Properties of Biosynthesis Silver Nanoparticles from Parkia speciosa (Stink Bean) Polysulfone Mixed Matrix Membrane

Green biosynthesis of silver nanoparticles (bio-AgNPs) provides an eco-friendly and effective approach to enhance the antibacterial performance and biofouling resistance of mixed-matrix membranes (MMMs). In this study, bio-AgNPs were synthesized using Parkia speciosa (Stink Bean) leaf extract as a reducing agent for silver nitrate and were incorporated into polysulfone (PSf) MMM to create bio-AgNP/PSf MMM. The antibacterial and antifouling properties of the bio-AgNP/PSF MMMs were compared with those of pristine PSf membranes and commercial AgNP/PSF MMMs. As a result, bio-AgNPs significantly increased hydrophilicity with contact angles of 65°, compared to 67° for AgNP/PSF MMM and 88° for the pristine PSf membrane. Surface roughness increased to 26.09 nm (bio-AgNP/PSf MMM) and 25.27 nm (AgNP/PSf MMM) from 3.73 nm (pristine). Meanwhile, pure water flux (PWF) results showed that bio-AgNP/PSf MMM achieved 248.7 L (m² h)⁻¹, compared to 239.5 L (m² h)⁻¹ for AgNP/PSf MMM and 84.2 L (m² h)⁻¹ for pristine PSf membrane. The rejection rates were 98% for the bio-AgNP/PSF MMM and 97% for the AgNP/PSF MMM. The bio-AgNPs/PSf MMM produced a larger inhibition zone (> 6 nm) against Escherichia coli (E. coli) than AgNPs/PSf MMM (< 6 nm), which was attributed to flavonoids enhancing the antibacterial properties. Both MMMs showed a flux recovery ratio (FRR) exceeding 80% after physical cleaning and 98% after chemical cleaning, indicating that bio-AgNP incorporation significantly improved the antibacterial and antifouling properties of MMMs.