Ravenna Grass-Extracted Alkaline Lignin-Based Polysulfone Mixed Matrix Membrane (MMM) for Aqueous Cr(VI) Removal

Studies have suggested that ecofriendly, inexpensive, and renewable material sources are essential for developing scalable, high-performance mixed matrix membranes (MMMs). With the fact that the second-most prevalent biomacromolecule in the world of plant biology is lignin, this article delineates the effective fabrication of a lignin-based MMM utilizing polysulfone (PSf) as the base material. The influence of PSf and the lignin concentration on the properties of the fabricated membranes was examined. Also, the developed membranes were assessed for surface morphology, roughness, thickness, thermal stability, functional groups, elemental composition, mechanical strength, and hydrophilicity. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) studies showed that the PSf/lignin membranes possessed a rough and inconsistent morphology and comparatively greater surface porosity. The water contact angle was reduced for the 1.0 wt % PSF/lignin membrane. Furthermore, lignin nanoparticles significantly impacted the membrane surface characteristics and decreased the ζ potential. Under the ideal experimental scenario, M2 (0.5 wt % lignin/PSf) and M3 (1.0 wt % lignin/PSf) membranes demonstrated good pure water flux values and a higher removal of 98.5 and 98.75% of Cr(VI), respectively. EDX analysis of the membranes after filtration affirmed the effective Cr(VI) removal from water. Owing to its low cost, green credentials, simplicity in synthesis, and remarkable efficiency, the newly developed PSf/lignin membrane is best suited for removing Cr(VI) and various other related contaminants from discharge aqueous effluents.