An innovative basalt fiber fabric-based mixed matrix pervaporation membrane for ethanol dehydration

Pervaporation (PV) has emerged as an efficient, energy-efficient membrane separation technology particularly suitable for separating azeotropes and mixtures with close boiling components, such as water and ethanol. PV membrane with high flux, excellent selectivity, and good stability is underdeveloped for industrial application. Mixed matrix membranes (MMMs) demonstrate significant potential for PV applications since they combine the benefits of polymeric and inorganic membranes. In this work, a rapid, cost-effective method for preparing the PV membrane based on environmentally friendly, biodegradable basalt fiber fabric (BF) was developed. Then, polyacrylonitrile (PAN) was employed as an interlayer to address the defects of large pore sizes in the supporting BF layer. Furthermore, carbon quantum dots (CQDs) synthesized via a one-pot method were used as functional fillers for forming a separation layer with sodium alginate (SA), which was stabilized via cross-linking using CaCl2 solution. Finally, the CQDs/SA and PAN/BF PV membrane (CQDs/SA-PAN@BF) was prepared. Performance tests showed that CQDs/SA-PAN@BF membrane with 2 wt% CQDs loading achieved a highest total flux of 572.96 g m−2 h−1 and a separation factor of 1108.06 under feed conditions of 75 °C and a 90 wt% ethanol-water solution. In addition, CQDs were found to enable faster flux and better selectivity, probably due to the enhanced hydrophilicity. The membrane process follows the “solution-diffusion” mechanism, and the hydrogen bonding between CQDs and SA promotes the dissolution and diffusion of water molecules. This study provides new materials, new methods, and insights into developing sustainable and high-performance PV membranes for ethanol dehydration and organic solvent recovery.