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

Magnesium-doped lithium manganese oxides (LimMgxMnyMnzO4)-Mn-III-O-IV (0 < x <= 0.5) with cubic spinel structure were synthesized by a coprecipitation method followed by calcination at 450 degrees C in air. Protonated samples were obtained after treatment with HCl solution. Chemical stability is very important for lithium uptake in industry. We used 0.5M 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.