Dissolution-time-induced structural transformation of areca husk-derived biomass toward self-assembled cellulose-PES membranes for efficient emulsified mixture separation

The rising environmental burden posed by emulsified waste engine oil in industrial effluents demands advanced separation platforms that combine efficiency with sustainability. In this study, a bio-derived membrane was fabricated through a dissolution-time-induced self-assembly strategy using areca husk-derived cellulose incorporated into a polyethersulfone (PES) matrix. Unlike conventional cellulose modification approaches relying on complex chemical functionalization or multi-step surface treatments, the present work demonstrates a solvent-mediated structural transformation and self-assembly mechanism for generating functional cellulose microspherical architectures under controlled dissolution conditions. FESEM analysis revealed progressive morphological evolution from fibrous fragments at 1 h to densely packed microspheres at 24 h, driven by cellulose chain rearrangement and intermolecular hydrogen bonding interactions. P-XRD analysis confirmed the coexistence of crystalline and amorphous domains, indicating the structural complexity of the self-assembled microspheres, while ATR-IR spectroscopy verified the successful incorporation of cellulose-specific functional groups within the modified membranes. The optimized 24 h membrane exhibited outstanding separation performance under continuous flow conditions, achieving > 98% rejection efficiency for dye-oil emulsified mixtures with a high permeation flux of 614 ± 3 L m −2 h −1 . Notably, the membrane demonstrated stable separation behaviour for multiple contaminant systems, including Congo Red (CR), Methylene Blue (MB), Red-Brown (RBr) dyes, and waste engine oil emulsions. This study highlights the critical role of dissolution time in tailoring the physicochemical properties and self-assembly behaviour of cellulose while advancing a sustainable and low-impact route for converting agro-waste into high-performance membrane materials for eco-efficient wastewater remediation and green environmental engineering applications.