Lancellotti Lidia, Bianchi Antonio, Kovtun Alessandro, Gazzano Massimo, Marforio Tainah Dorina, Xia Zhen Yuan, Calvaresi Matteo, Melucci Manuela, Zanardi Chiara, Palermo Vincenzo
Institute for Organic Synthesis and Photoreactivity, National Research Council (ISOF-CNR), via Piero Gobetti 101, 40129, Bologna, BO, Italy.
Department of Chemistry 'G. Ciamician', Alma Mater Studiorum University of Bologna, via Selmi 2, 40126 Bologna, Italy.
Nanoscale. 2024 Apr 4;16(14):7123-7133. doi: 10.1039/d3nr05874c.
Filters made of graphene oxide (GO) are promising for purification of water and selective sieving of specific ions; while some results indicate the ionic radius as the discriminating factor in the sieving efficiency, the exact mechanism of sieving is still under debate. Furthermore, most of the reported GO filters are planar coatings with a simple geometry and an area much smaller than commercial water filters. Here, we show selective transport of different ions across GO coatings deposited on standard hollow fiber filters with an area >10 times larger than typical filters reported. Thanks to the fabrication procedure, we obtained a uniform coating on such complex geometry with no cracks or holes. Monovalent ions like Na and K can be transported through these filters by applying a low electric voltage, while divalent ions are blocked. By combining transport and adsorption measurements with molecular dynamics simulations and spectroscopic characterization, we unravel the ion sieving mechanism and demonstrate that it is mainly due to the interactions of the ions with the carboxylate groups present on the GO surface at neutral pH.
由氧化石墨烯（GO）制成的过滤器在水净化和特定离子的选择性筛分方面具有广阔前景；虽然一些结果表明离子半径是筛分效率的判别因素，但筛分的确切机制仍在争论中。此外，大多数报道的GO过滤器都是具有简单几何形状的平面涂层，其面积比商用滤水器小得多。在这里，我们展示了不同离子在沉积于标准中空纤维过滤器上的GO涂层中的选择性传输，该过滤器的面积比报道的典型过滤器大10倍以上。由于制造工艺，我们在这种复杂几何形状上获得了均匀的涂层，没有裂缝或孔洞。通过施加低电压，像Na和K这样的单价离子可以通过这些过滤器传输，而二价离子则被阻挡。通过将传输和吸附测量与分子动力学模拟以及光谱表征相结合，我们揭示了离子筛分机制，并证明这主要是由于在中性pH值下离子与GO表面存在的羧基之间的相互作用。
