Magnesium-Doped Manganese Oxide with Lithium Ion-Sieve Property: Lithium Adsorption from Salt Lake Brine

Abstract Magnesium-doped lithium manganese oxides LimMgxMnIIIyMnIVzO4 (0 < x ≤ 0.5) with cubic spinel structure were synthesized by a coprecipitation method followed by calcination at 450 °C in air. Protonated samples were obtained after treatment with HCl solution. Chemical stability is very important for lithium uptake in industry. We used 0.5 M HCl for desorption of lithium, then dissolution of Mn decreased from 5.8 wt % for a sample without Mg to 1.0 wt % for a Mg-doped sample (Mg/Mn = 0.33). Raw brine was collected from the Salars de Uyuni, Bolivia. The effects of magnesium-doping on lithium adsorptive properties of the protonated samples in NaHCO3 containing brine were studied by a batch method. The results showed that lithium adsorptive capacity and chemical stability of the protonated samples increased with increase in Mg/Mn ratio. The regeneration of the sample with Mg/Mn = 0.33 up to 10 cycles showed good performance with lithium adsorptive capacity of 23–25 mg g−1 at pH 6.6, and the dissolution of manganese ca. 0.25 wt % Mn.