Synthesis of highly porous layered hydrogen titanium oxide(HTO) granule by using carboxymethylated cellulose nanofibrils(CMCNFs) for effective recovery of Lithium(Li) from low-grade brines

Layered hydrogen titanium oxide (HTO) shows potential for lithium (Li) recovery from low-grade brines, but its practical use is hindered due to its particulate nature. In this study, we developed highly porous HTO granules using carboxymethylated cellulose nanofibrils (CMCNFs) as a binder (CMCNF@HTOs) and evaluated their Li adsorption efficiency in simulated brines. These granules were produced by combining a 5 wt% CMCNF solution with varying HTO powder weight ratios, followed by freeze-drying and thermal cross-linking. Optimal conditions yielded granules with over 93.48 % mechanical stability and more than 51.22 % porosity, using a 10:1 CMCNF solution to HTO powder ratio. The HTO powder is homogeneously distributed on the granules with 66.60 % of contents. The CMCNF@HTO demonstrated a maximum Li adsorption capacity of 34.72 mg/g, only a 6.77 mg/g reduction compared to pure HTO powder (41.49 mg/g). This minimal decrease in capacity is attributed to the granules' highly porous structure from freeze-drying and the hydrophilic properties of CMCNFs, which mitigated the brine diffusion interference. Furthermore, the effectiveness of CMCNF@HTOs was tested in various simulated brines, including those from the Salton Sea, saline groundwater, and the Great Salt Lake. Notably, in each brine, the CMCNF@HTOs selectively recovered only Li, underscoring their practicality for Li extraction from diverse low-grade brine sources.