Highly Efficient Pervaporation Dehydration of Isopropanol Using Gd-BTC Modified Sodium Alginate Mixed Matrix Membranes

This study presents, for the first time, a comprehensive investigation of gadolinium-based metal–organic framework (Gd-BTC) as a filler in sodium alginate (SA) membranes for pervaporation dehydration of isopropanol (IPA). A series of dense and supported mixed matrix membranes were fabricated and characterized. The optimal dense SA/Gd-BTC(20 wt %) membrane demonstrated an up to 2.3-fold increase in permeation flux over the pristine SA membrane for separation of water–IPA mixtures, while maintaining high selectivity (>99.5% water in the permeate). Subsequent cross-linking with CaCl2 further improved the selectivity and operational stability of this membrane. Furthermore, a cross-linked supported membrane from SA/Gd-BTC(20 wt %) on porous polyacrylonitrile substrate was engineered, achieving an exceptionally high permeation flux of up to 2 kg m–2 h–1. The enhanced performance is attributed to improved membrane hydrophilicity, favorable polymer–filler interactions leading to morphological changes, and polymer reorganization during cross-linking, as confirmed by FTIR, XRD, SEM, AFM, DFT calculations, and other techniques. A comparison of the transport properties of the developed membranes with those reported in the literature highlights Gd-BTC as a highly promising filler for overcoming the permeability–selectivity trade-off, providing an effective strategy for energy-efficient industrial alcohol dehydration.