Designing Confined Thermal-Recognized Hydrogen Bonding Nanochannels for Effective and Energy-Efficient Water Isotopologue Sieving

Abstract

Water isotopologue sieving has been flagged as one of the biggest challenges in modern separation technologies owing to their extremely similar physicochemical properties. As a benchmark candidate, current membrane separation suffers from inferior water isotopologue sieving as imposed by the failure of the size exclusion in conventional membrane separation. Herein, a facile approach is presented to elaborate MXene/Cellulose nanofiber (CNF) membranes featuring confined thermal-recognized hydrogen bonding nanochannels, enabling highly-selective, energy-efficient and durable deuterium water sieving under low-grade heat. The key to such membranes lies in the meticulous utilization of CNF-enabled rich thermal-recognized hydrogen bonds within nanochannels, which attract more deuterium water and water via deuterium bond and hydrogen bond (─OD/─OH) meanwhile thermally recognizing deuterium water with stable ─OD interaction to create more significant diffusion kinetic differences over water under low-grade heat. It is demonstrated that the MXene/CNF membranes deliver an extraordinary separation factor as high as 5.2 yet demanding energy consumption as low as 2.9 GJ kg−1, outperforming most of state-of-the-art separation technologies. Moreover, the MXene/CNF membrane exhibits stable separation performance under long-term operations and can be further integrated into multi-stage separation device for augmenting separation and concentration of deuterium water, making it a step closer to the practical applications.