Application and limitations of a H2TiO3 - Diatomaceous earth composite synthesized from titania slag as a selective lithium adsorbent

The lithium adsorption properties of H2TiO3 synthesized from titania slag and immobilized on diatomaceous earth was investigated. Batch adsorption studies using a LiCl buffered solution (pH = 9.5) shows a maximum adsorption capacity of 27.4 mg/g. Isotherm and kinetic studies indicate that lithium adsorption takes place heterogeneously via a chemisorption mechanism. When tested in a low-grade lithium brine (i.e., The Great Salt Lake, Utah, USA (Li+ similar to 20 mg/L)), the adsorbent composite demonstrated high selectivity towards lithium over magnesium and sodium (selectivity factor > 40) with good recyclability at room temperature. However, despite its relatively high adsorption capacity in a buffered solution, the adsorption capacity and the rate of lithium adsorption drastically decreases in brine solution compared to the buffered solution due to the release of H+ ions during ion-exchange. The lithium adsorption capacity decreased with increasing temperature due to the loss of adsorption sites, which is a result of the hydrolysis of metastable H2TiO3 at higher temperatures. This decomposition of the adsorbent is a result of the destabilizing effect of H2TiO3 on DE.