Mechanochemical synthesis of silica-lithium manganese oxide composite for the efficient recovery of lithium ions from seawater

Abstract

In this study, to prevent manganese dissolution from an acid treatment during the extraction of lithium ions (Li+), silica (SiO2) was mixed mechanically with lithium manganese oxide (Li1.33Mn1.67O4, LMO) by a high-energy milling technique followed by calcination. The milling process ensured high-level chemical homogeneity of metal oxides. The amorphous SiO2 imparted stability to the LMO spinel structure and reduced the level of Mn dissolution during the extraction of Li+ using an acid. X-ray diffraction and thermogravimetric analysis confirmed that the amorphous SiO2 was well mixed in the framework of LMO. The Li-Si-Mn-O composite was used as an efficient adsorbent for the recovery of Li+ from lithium spiked seawater with an adsorption capacity of 43.23 mg g(-1). The adsorption process fitted the Langmuir isotherm well with a correlation coefficient of 0.9831. The kinetic study showed that the adsorption behavior followed pseudo-second-order kinetics. The adsorbent exhibited excellent selectivity towards Li+, even in the presence of competitive cations with a higher concentration than Li+.