Zwitterionic vinylene-linked covalent organic frameworks mixed matrix membranes for high-efficient bioethanol dehydration

Fuel-grade bioethanol demonstrates significant advantages as an environmentally friendly and renewable energy source. However, its further deployment is constrained by energy efficiency dehydration of the ethanol–water azeotrope. Membrane separation technology, recognized for its energy efficiency, is widely used in purification applications. Among the available materials, polymer membranes such as sodium alginate (SA) have been extensively studied. However, their practical application is significantly limited by a fundamental trade-off between permeability and selectivity, compounded by a susceptibility to plasticization. To address these challenges, we herein report a novel mixed matrix membrane (MMM) incorporating zwitterionic covalent organic framework with stable vinylene-linkage (ZVCOF) fillers within a SA matrix. The introduction of ZVCOF strengthens the physicochemical structure of the pristine SA membrane by suppressing membrane swelling while simultaneously improving hydrophilicity and pervaporation performance. The membrane with 5 wt% ZVCOF loading exhibited a water permeation flux of 2129.8 g m −2 h −1 alongside a separation factor of 1021.2, representing a 3.5-fold enhancement in selectivity compared to the pristine SA membrane. Moreover, the MMMs demonstrated excellent operational stability over 120 h of continuous testing, highlighting its strong potential for industrial application. The high-performance and durable MMMs suggest their potential for practical bioethanol dehydration.