Green modification of forward osmosis membrane using lignocellulosic biomass for water and valuable resource recovery from seawater brine

Lignin-rich biomass with enhanced hydrophilicity shows promise in membrane modification, leading this study from sodium lignosulfonate (SL) biomass to Castanea shell (CS) biowaste for modifying the active polyamide (PA) and support polysulfone (PSf) layers of composite forward osmosis membrane (CFOM) to present an eco-friendly modification strategy and achieve waste valorization . The enhancement of CFOM performance , particularly in permeate flux while maintaining low and stable reverse solute flux (RSF), was achieved remarkably, resulting in exceptional permeate flux of 9.2 LMH and 22.1 LMH with 1 wt% CS water-extracted solution in PA layer (PA 1.0CS -PSf 0 ) and 1 wt% SL particles in PSf layer (PA 0 -PSf 1.0SL ), respectively, using DI water and 1 M NaCl as feed and draw solutions (FS and DS), with a low reverse solute flux of 0.1 nMH. Furthermore, this study tested the synthesized CFOMs for practical application in coastal agriculture by employing seawater and 4 M potassium chloride fertilizer as FS and DS, respectively, aiming to achieve simultaneous water recovery and liquid fertilizer production. In real brine applications, PA 1.0CS -PSf 0 achieved 45.1% water recovery within 24 h with a 1.1-fold improvement over virgin CFOM, and retained 92.6% flux recovery rate, demonstrating its exceptional permeability performance and anti-fouling properties. Therefore, this study not only addresses water recovery challenges but also creates a sustainable cycle by utilizing biowaste for membrane modification and generating concentrated fertilizer solution, offering a comprehensive solution for both waste valorization and sustainable coastal agriculture. • Lignocellulosic-biomass-modified membrane shows practical in seawater brine recovery. • Modified membrane achieved balanced reverse solute flux and high permeate flux. • Sustainable membrane modification achieved 45.1 % water recovery rate from seawater brine. • Excellent recovery rates of valuable ions (Sr, B, and Li) were achieved during both synthetic and real brine treatment.