Extraction of Lithium from Single-Crystalline Lithium Manganese Oxide Nanotubes Using Ammonium Peroxodisulfate

Abstract

In this work, a spinel single-crystalline Li1.1Mn1.9O4 has been successfully synthesized using β-MnO2 nanotubes as the self-sacrifice template. The tubular morphology was retained through solid-state reactions, attributed to a minimal structural reorganization from tetragonal β-MnO2 to spinel Li1.1Mn1.9O4. The materials were investigated as sorbents for lithium recovery from LiCl solutions, recycled using H2SO4 and (NH4)2S2O8. Li1.1Mn1.9O4 nanotubes exhibited favorable lithium extraction behavior due to tubular nanostructure, single-crystalline nature, and high crystallinity. (NH4)2S2O8 eluent ensures the structural stability of Li1.1Mn1.9O4 nanotube, registering a Li+ adsorption capacity of 39.21 mg g−1 (∼89.73% of the theoretical capacity) with only 0.08% manganese dissolution after eight adsorption/desorption cycles, compared to that of 1.21% for H2SO4. It reveals the degradation of sorbent involves with the volume change, Mn reduction, and Li/Mn ratio depletion. New strategies, based on nanotube adsorbent and (NH4)2S2O8 eluent, can extract lithium ions at satisfactorily high degrees while effectively minimizing manganese dissolution.