Preparation of effective lithium-ion sieve from sludge-generated TiO2

A potential adsorbent for Li+ extraction from liquid resources is titanium-type lithium-ion sieves (LISs) because of their structural stability and high adsorption capacity. However, the adsorption efficiency and recycling stability of LISs produced with various TiO2 precursors vary significantly. Additionally, traditional TiO2 is often produced using chemical-intensive methods, resulting in large amounts of effluent containing strong acids and high concentrations of chloride/sulfate ions, posing a threat to the environment. Hence, in this study, the LIS precursors, Li2TiO3, were synthesized utilizing novel environment-friendly anatase titania made from flocculated sludges of synthetic secondary sewage effluent (S-LTO) and dye wastewater (D-LTO). The physicochemical characteristics and adsorption capacities of the synthesized LISs were then investigated. The results indicated that sludge-generated LISs could be effectively produced and had a high Li+ adsorption capacity of 35.43 mg/g for S-LTO and 34.97 mg/g for D-LTO. For the synthesized LISs, the adsorption kinetics and isotherms verified a fixed energy-based monolayer chemisorption. Furthermore, the H2TiO3 generated from sludge was extremely stable after acid pickling, reusable (4 regeneration cycles exhibited minimal performance degradation), and highly selective to Li+ in an aqueous medium, suggesting enormous industrial potentials such as seawater and brine for aqueous Li+ recovery.