2-(Allyloxy) methylol-12-crown-4 ether functionalized polymer brushes from porous PolyHIPE using UV-initiated surface polymerization for recognition and recovery of lithium

Abstract

It is highly desirable to develop an efficient adsorbent with large capacity, high selectivity and fast kinetics to recovery virtually inexhaustible lithium ion (Li+) resources from salt lake brine. In this work, 2-(allyloxy) methylol-12-crown-4 ether (2AM12C4) functionalized polymer brushes (PVBC-g-PCE) from macroporous polymeric high internal-phase emulsion (PolyHIPE) using UV-initiated surface polymerization are synthesized for selectively recovery of Li+. PVBC-g-PCE possesses the advantages of strong physical strength, high density of accessible binding sites, and the size of highly permeatable voids and interconnecting pores is about 8.0–18 µm and 3.3–4.8 µm, respectively, which is a favorable adsorbent for specific capture Li+. PVBC-g-PCE has a maximum capacity at pH 6.0, and the pH-dependent adsorption amount suggests the grafted polymer brushes of 2AM12C4 is the driving force to enhance binding performance. PVBC-g-PCE has a fast adsorption equilibrium within 45 min, and the kinetic results are well-described by the pseudo-second-order model, indicating the specific host-guest interaction between functionalized 2AM12C4 and Li+ is the main adsorption mechanism. Moreover, the maximum monolayer binding amount of PVBC-g-PCE is 4.43 mg g−1, and the strong affinity in the presence of four kinds of interfering ions (i.e. Na+, K+, Mg2+, and Ca2+) is also observed, which can also be proved by the high relative selectivity separation coefficient (αr) between 3.16 and 7.98. It is expected that this PVBC-g-PCE with abundant easy-to-access specific recognition sites can be applied as a promising adsorbent for effective separation of Li+.