Advanced graphitic carbon nitride-based membranes for ionic resource recovery

Resource recovery from wastewater, seawater and salt lakes has attracted significant attention due to its economic and environmental benefits. Recent achievements in membrane technology have allowed efficient recovery of ionic resources from water, and various membranes have been developed to selectively reject, and recover salts and metals in water steams. With the requirement of high ion selectivity, a wide range of nanomaterials are employed in these membranes. Graphitic carbon nitride (g-C3N4), as two-dimensional nanosheets, with an abundant and intrinsically uniform pore structure network, tunable interlayer spaces, easy and low-cost synthesis, tailored functionality and promising stability, shows high prospects for ion -selective separation. This comprehensive review outlines the development of advanced g-C3N4-based membranes for ionic resource recovery. First, design strategies of g-C3N4 nanosheets for membranes are highlighted in terms of experimental characteristics and molecular dynamic simulations. Next, g-C3N4-based membranes made as lamellar membranes and mixed matrix membranes are emphasized, based on their preparation method. Finally, current applications of g-C3N4-based membranes in ionic resource recovery are presented: valuable ion extraction, metal ion separation, radionuclide capture and desalination. This tutorial review provides insightful guidance on the design strategies, fabrication methods and ionic resource recovery applications of g-C3N4-based membranes for resource sustainability.