Chemically crosslinked electrospun chitosan/poly (vinyl alcohol) membranes with encapsulated zeolite for organic dye removal

Safe water is a basic human right, yet about 25 % of the global population lacks reliable access. Rapid urbanization and industrialization, especially in developing countries, have worsened water pollution, causing environmental and health issues. To achieve global safe water goals, affordable and effective wastewater treatment solutions are needed. To this end, zeolites are highly effective for wastewater treatment due to their unique adsorption properties; however, their efficacy can be significantly hindered due to a propensity to aggregate. Herein, electrospun chitosan (CS)/polyvinyl alcohol (PVA) membranes are fabricated to encapsulate sodium Y (NaY) zeolites, preventing their unwanted aggregation. By utilizing 1,1’-Carbonyldiimidazole (CDI) as a green crosslinker, NaY could be effectively immobilized within the electrospun membranes. CDI crosslinking enhanced the mechanical properties of the composite membranes, with improved Young's Modulus, ultimate tensile stress, and toughness as compared to non-crosslinked membranes. After optimizing the electrospinning process and formulation, as a proof of concept membrane modules were prepared and tested for the filtration of methylene blue (MB) as a model organic dye. Continuous filtration tests showed effective MB removal, achieving a 95 % removal rate and 287 LMH flux at an initial MB concentration of 50 mg/L, using a 1 g/L adsorbent dosage. Crucially, these membranes showed good mechanical stability and potential to be regenerated/recycled, yielding only a 13 % decrease in performance after five adsorption/desorption cycles. We anticipate that this approach could lead to the development of functional membranes for removing organic dyes and other emerging contaminants from water, directly improving access to safe, clean water.