To develop an adsorbent for Li + recovery from seawater and/or spent lithium batteries, a benzo‐12‐crown‐4 ether (B12C4) moiety was immobilized with silica (immobilization yield: 0.70 meq g −1 ). Compared to pure silica, the resulting adsorbent (FB12C4‐SG) had a reduced Brunauer–Emmett–Teller surface area (500 vs. 180 m 2 g −1 ) and pore volume (0.75 vs. 0.26 cm 3  g −1 ). The Li + adsorption reached equilibrium at 31 mg g −1 after 2 h (1000 ppm Li + solution). The adsorption behavior was well explained by pseudo‐second‐order kinetics and the Langmuir adsorption model (maximum adsorption capacity: 33 mg g −1 ). The material exhibited a Li + /Na + adsorption selectivity factor of 4.2 and high chemical stability under acidic regeneration conditions (1.0 N HCl solution).

To develop an adsorbent for Li+ recovery from seawater and/or spent lithium batteries, a benzo-12-crown-4 ether (B12C4) moiety was immobilized with silica (immobilization yield: 0.70 meq g1). Compared to pure silica, the resulting adsorbent (FB12C4-SG) had a reduced Brunauer–Emmett–Teller surface area (500 vs. 180 m2 g1) and pore volume (0.75 vs. 0.26 cm3 g1). The Li+ adsorption reached equilibrium at 31 mg g1 after 2 h (1000 ppm Li+ solution). The adsorption behavior was well explained by pseudo-second-order kinetics and the Langmuir adsorption model (maximum adsorption capacity: 33 mg g1). The material exhibited a Li+/Na+ adsorption selectivity factor of 4.2 and high chemical stability under acidic regeneration conditions (1.0 N HCl solution).