Acid Resistant and Highly Silver Selective Membranes Based on Charged Nanoporous 2D-Materials.

The amount of waste electrical and electronic equipment (WEEE) is growing rapidly, yet less than a quarter of it is recycled. These "urban mines" contain valuable and critical metals that must be recovered. Therefore, developing more sustainable and energy-efficient separation techniques is essential. Membrane technology has demonstrated this capability, particularly those based on 2D materials, due to their atomic thickness and the ability to precisely tune pore size. This report introduces a novel nanofiltration membrane fabricated from charged, fully exfoliated, nanoporous 2D nanosheets. Developed for ion separation, it exhibits exceptional selectivity for silver (Ag) over other metals typically found in WEEE leachates-a feature highly relevant for solar panel recycling. Furthermore, its rare stability in acidic media makes such an approach advantageous for hydrometallurgical processes. Notably, we demonstrate that these charged 2D membranes exhibit two distinct ion transport mechanisms, intra- and inter- lamellar, to achieve remarkable and rapid separation within 2 min.