A facile coordinate complexing of Na(I) to fabricate SPB-ACE@MS-4A for selective adsorption to monovalent alkali metal ions

In wastewaters containing high levels of salts, alkali metal ions constitute a majority of those ions. Alkali metals have a small radius and low polarization rate. We prepared a composite adsorbent, SPB-ACE@MS-4A, by a straightforward method. A 4-aminobenzoic crown ether modified spherical polymer brush (SPB-ACE) was prepared via coupling and co-deposition. The SPB-ACE was loaded onto 4A molecular sieves (MS-4A) to develop a ternary cooperative adsorbent (SPB-ACE@MS-4A). The 4-aminobenzoate-15-crown-5 (ACE) formed complexes with Na(I) by supramolecular action because the cavity size approximated that of Na(I), which addressed the problem of poor selectivity for monovalent alkali metal ion adsorption. In the presence of multiple ions, SPB-ACE@MS-4A material selectively favored monovalent alkali metal ions. Our results yielded an adsorption capacity, partition coefficient and a Na(I) removal rate of 364.76 mg/g, 10.35 L/g and 91.19%, respectively, for alkali metal ion removal by SPB-ACE@MS-4A at room temperature. The novel structure can provide new insights for the development of a new generation of environmentally sensitive salt adsorption materials to achieve more effective and selective water desalination and purification.