Composite alginate membranes with dispersed MQFP hard magnet network as a new concept for highly efficient pervaporative dehydration of ethanol/water mixture

Magnetic particles have been recently considered as appealing functional fillers in composite membranes used for versatile purposes, for instance for the pervaporative dehydration of ethanol. The application of superparamagnetic or ferromagnetic materials with soft magnetic properties has been confirmed as a promising strategy to improve separation efficiency. Nevertheless, current studies seem to neglect the possibility of using hard magnetic membranes, even though they exhibit high value of saturation magnetization along with a high coercivity. To fill in the existing knowledge gap, in this study we presented the improvement of pervaporative ethanol dehydration process through the application of alginate membranes filled with hard magnets in the form of a Magnequench fine powder (MQFP). To provide an extensive analysis of their physicochemical and magnetic properties, both powder and composite membranes were comprehensively characterized by means of magnetometry, electron microscopy and a position annihilation lifetime spectroscopy. The presence of MQFP was confirmed to provide hard magnetic properties to MQFP/alginate membranes, particularly for materials with lower content of magnetic powder (1 wt% MQFP). The results showed that the magnetic properties, amount and size of MQFP particles had a significant impact on the efficiency and separation properties of the water/ethanol pervaporation process. Consequently, the highest value of separation factor (12271) was reached for an alginate membrane filled with 1 wt% of MQFP powder with the grains size of 15 µm.