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

• Published in: Separation and purification technology 2021-01, Vol.254, p.117580, Article 117580
• Main Authors: Marthi, Rajashekhar, Smith, York R.
• Format: Article
• Language: English
• Subjects: Adsorption; Brine; Lithium
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2020.117580

•A lithium ion sieve composite was derived from titania slag.•Adsorption is described by the Freundlich model and pseudo second order kinetics.•High selectivity for lithium over alkali and alkaline earth metals is demonstrated.•Hydrolysis of metastable H2TiO3 occurs at higher temperatures, reducing performance. 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+ ~ 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.