The protonated product of lithium titanate (H2TiO3, HTO) is a promising adsorbent for lithium recovery from alkaline aqueous streams due to its high selectivity and cycling stability. This study investigates how precursor pretreatment influences the solid-state synthesis of its parent phase, monoclinic Li2TiO3 (LTO), and the resulting lithium adsorption performance of HTO. Multiple commercial TiO2 sources and pre-synthesis methodologies, including grinding, ball-milling, and ultrasonication in water, isopropanol, or ethanol, were evaluated for their impact on phase formation and textural properties. X-ray diffraction analysis revealed that high-energy ball-milling results in α-LTO after calcination, a phase that fails to produce effective Li-adsorbing HTO. In contrast, ultrasonication and conventional mixing preserve the desired monoclinic β-LTO structure. HTO derived from monoclinic LTOs exhibited superior performance, with adsorption capacities up to 25.84 mg g−1 and kinetic constants more than twice as high compared to untreated controls. All monoclinic HTOs followed pseudo-second-order kinetics and fit the Langmuir isotherm model, confirming monolayer adsorption. High lithium selectivity was maintained, as demonstrated by selectivity factors such as = 660, and = 2927 for HTOs obtained via ultrasonication in water. In contrast, materials derived from cubic LTO showed negligible lithium selectivity. Notably, HTO prepared via ultrasonication in water matched or exceeded solvent-based methods in performance, offering a more sustainable and scalable processing route. Repeated adsorption-desorption cycles using synthetic brines demonstrated consistent lithium recovery of approximately 30 % per cycle, and minimal titanium leaching. These findings underscore the critical role of precursor pre-treatment in tailoring the properties of lithium sorbents via solid-state synthesis, and identify ultrasonication in water as a scalable, eco-friendly approach to produce high-performance HTO.
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Lithium manganese oxides (LMO) are highly promising sorbents for lithium extraction from Li
-containing brines with high salt contents due to their high sorption capacity and high selectivity toward lithium. However, conventional synthesis routes are limited in scale. Therefore, a novel spray-drying method is presented herein, enabling a scalable synthesis of LMO sorbents for Li
extraction. The ion-exchange material is studied in both synthetic LiCl solutions and two different geothermal brines from the Upper Rhine Valley, demonstrating improved Li selectivity and extraction capabilities compared to materials from hydrothermal synthesis approaches. The extraction behavior in relevant mildly acidic environments is studied in detail. Further material improvements are achieved by substituting a fraction of Mn by Ti, which greatly reduced the dissolution of manganese during acid treatment in the first 5 extraction cycles from 5.6% to only 1.8%. In addition, the maximum sorption capacity of the Ti-substituted LMO (LMTO) can be further increased from 5.05 mmol g
for LMO (35.1 mg g
) to 5.66 mmol g
for LMTO (39.3 mg g
) under optimized m/V ratios. Hence, the results reported herein present a pathway toward LMO-based ion-exchange materials for the direct lithium extraction on an industrial scale.
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The Upper Rhine Graben (URG) is a highly promising area for geothermal lithium (Li) extraction. Li concentration in deep geothermal brine circulating in naturally fractured Visean and Triassic reservoirs exceed 150 mg/L and are combined with significant water flows exploited by geothermal plants. However, there are still a lack of knowledge in the fluid-rock interactions leading to present high Li concentration in the geothermal brine. To address the behavior of Li in the crystalline reservoir during hydrothermal alteration, 36 granite rock samples were selected from 3 deep geothermal wells at Soultz-sous-Forêts (GPK-1, GPK-2 and EPS-1) in France. These samples were analyzed both chemically and mineralogically to assess the impact of dissolution/precipitation on major elements together with Li precipitation in mineral phases or solubilization in the brine. In total, 4 different main alteration facies from low to high alteration grades were identified in the 36 granite samples (fresh granite, propylitic alteration, argillic alteration, argillic alteration and fractured) that displayed significant chemical, mineralogical and textural changes. The Li concentration of the total rocks range from 18 to 1938 ppm and could be attributed to secondary mineral precipitation (illite, illite/smectite and chlorite/smectite mixed layers, quartz, carbonates, barite) and hydrothermal alteration by partial dissolution of the main minerals (biotite, chlorite, feldspars) present in the granite. These results highlight the importance of fluid-rock interactions due to hydrothermal circulation in the mobilization of Li in the reservoir and refine the story behind high Li concentration in the URG brine.
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In order to mitigate the risks associated with cobalt supply, a safe and affordable LiFePO4-based (LFP) cathode for Li-ion batteries can be a significant solution to meet the rapidly growing battery market. However, economical and environmentally friendly recycling of LFP is impossible with currently available recycling technologies. In this study, an acid-free mechanochemical approach is applied to reclaim Li from LFP using Al as a reducing agent. The reaction mechanism involved in reductive ball-milling followed by water leaching has been elucidated through the examination of various milling times and molar ratios of components, fostering a deeper understanding of the process. Assessing the yield and purity of the final products provides insights into potential enhancements for this technology. Utilizing Al as the material of the current collector eliminates the need for additional external additives, thereby simplifying the recycling workflow. Continued research into this process has the potential to facilitate efficient and economical recycling of LFP materials.
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The conventional lithium extraction method involves the calcination of a-spodumene at 1050 °C so that it can be converted to the more-reactive b-spodumene and then a sulfuric acid roasting step at 250 °C. Lithium is finally extracted via leaching with water. This method is energy-intensive, leading to high capital and operational costs. In this study, the direct calcination of a-spodumene with the use of sodium carbonate and calcium oxide was examined, aiming to significantly reduce the calcination temperature and completely omit the sulfuric acid roasting step, thereby radically redesigning the lithium extraction process. The calcination product was then leached with different leaching agents, such as water and sulfuric acid, and at different temperatures. The efficiency of the additives was evaluated through the results of lithium extraction achieved during the leaching step. Different leaching agents and temperatures were investigated. The maximum lithium extraction achieved was 96%, obtained after calcination using a sodium carbonate/spodumene mixture and leaching with sulfuric acid at 90 °C. High lithium extractions, up to 83%, can also be achieved under the same calcination conditions and after leaching with sulfuric acid at lower temperatures, such as 40 °C, and for shorter leaching times.
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The poster is available in German and was presented at the German geothermal conference in Essen (October, 2023). Its summary is available in English in the article New membrane-free technique for the selective separation of lithium and sodium.