Fabrication and evaluation of aminoethyl benzo-12-crown-4 functionalized polymer brushes adsorbents formed by surface-initiated ATRP based on macroporous polyHIPEs and postsynthetic modification

Abstract For the efficient extraction of lithium ions (Li+) from salt-lake brines, adsorbents with high adsorption capacity, fast equilibrium rate, and excellent selectivity are urgently needed. Herein, aminoethyl benzo-12-crown-4 (2AB12C4) functionalized polymer brushes (PVBC-g-PGMA-CE) from macroporous and polymeric high internal-phase emulsion (polyHIPEs) using surface-initiated ATRP and postsynthetic modification was constructed for selective recovery of Li+. Owing to the macroporous structure and high density of binding sites of PVBC-g-PGMA-CE, the equilibrium time was 50 min, and the maximum adsorption capacity was 4.76 mg g−1 at 25 °C. The equilibrium and kinetic studies indicated a monolayer and chemisorption process via homogeneous sites and host-guest interaction. Attributed to the size sieving effect and affinity difference, PVBC-g-PGMA-CE possessed the highest the binding capacities towards Li+ in the competitive adsorption, and the relative selective separation factors (αr) for coexisting ions (i.e. Ca2+, Mg2+, Na+ and K+) were all higher than 4.67. The adsorption amount of PVBC-g-PGMA-CE towards Li+ after five regeneration cycles was 97.30% of the first cycle. The results demonstrated that the developed PVBC-g-PGMA-CE was the promising adsorbent for the efficient and selective recovery of Li+.