Advanced magnetic membranes with chromite fillers: role of structure and magnetism in ethanol pervaporation

• Chromite filler and magnetism influence membrane separation efficiency. • CuCr 2 Se 4 improves water transport through strong ferromagnetic arrangement. • Concentration of filler controls magnetic channel formation. • Magnetic interactions promote selective water channels over ethanol. Developing high-performance membranes for ethanol dehydration is crucial for energy-efficient biofuel production. This study presents novel sodium alginate-based composite membranes incorporating magnetic selenide chromite fillers (CuCr 2 Se 4 , ZnCr 2 Se 4 , CdCr 2 Se 4 ) and evaluates their pervaporation performance. The fillers were selected for their magnetic properties, which are hypothesised to facilitate selective water transport through the membrane matrix. Morphological and physicochemical analyses confirmed uniform filler dispersion at an optimal loading of 3 wt%, enhancing membrane performance. The membrane containing CuCr 2 Se 4 , a ferromagnetic filler, exhibited the highest pervaporation separation index (PSI), reaching 1308 kg∙m −2 ∙h −1 , significantly surpassing the performance of ZnCr 2 Se 4 - and CdCr 2 Se 4 -based systems. Further optimisation under various feed temperatures and ethanol concentrations revealed that lower temperatures and higher ethanol content improved separation efficiency. These results highlight the potential of magnetic selenide chromites as functional fillers in pervaporation membranes for advanced bioethanol purification.