Sustainable lithium extraction enabled by responsive metal-organic frameworks with ion-sieving adsorption effects

Synthesis and Osteoinductive Properties of Nanosized Lithium-Modified Calcium-Organic Frameworks

The development of biomaterials that enhance bone healing and integrate with native bone tissue has gained significant interest. Metal-organic frameworks (MOFs) have emerged as promising candidates due to their unique surface properties and biocompatibility. While various bioactive element-incorporated MOFs have been studied, the osteogenic potential of lithium (Li)-modified MOFs remains largely unexplored. This study presents the synthesis and characterization of a nanosized calcium-based MOF incorporating Li⁺ ions to enhance osteoinductive properties. The MOFs were evaluated in vitro for apatite mineralization, degradation, ion release, protein adsorption, cell adhesion, viability, and osteogenic differentiation using pre-osteoblast cells. The synthesized MOFs promoted apatite formation under simulated physiological conditions, facilitated by their surface nucleation properties, controlled degradation, and sustained Li+ and Ca2+ ion release. Cytocompatibility assays confirmed excellent pre-osteoblast adhesion and viability. Furthermore, CaMOF nanoparticles stimulated osteogenic differentiation by enhancing alkaline phosphatase (ALP) activity, even in the absence of osteogenic supplements. Among tested MOFs, Li/CaMOF exhibited the highest osteoinductive potential. These findings highlight lithium-modified MOFs as promising biomaterials for bone regeneration. However, further in vivo studies are necessary to assess their long-term stability, bone integration, and clinical applicability.

Electro-driven direct lithium extraction from geothermal brines to generate battery-grade lithium hydroxide

As Li-ion batteries are increasingly being deployed in electric vehicles and grid-level energy storage, the demand for Li is growing rapidly. Extracting lithium from alternative aqueous sources such as geothermal brines plays an important role in meeting this demand. Electrochemical intercalation emerges as a promising Li extraction technology due to its ability to offer high selectivity for Li and its avoidance of harsh chemical regenerants. In this work, we design an economically feasible electrochemical process that achieves selective lithium extraction from Salton Sea geothermal brine and purification of lithium chloride using intercalation materials, and conversion to battery grade (>99.5% purity) lithium hydroxide by bipolar membrane electrodialysis. We conduct techno-economic assessments using a parametric model and estimated the levelized cost of LiOH•H2O as 4.6 USD/kg at an electrode lifespan of 0.5 years. The results demonstrate the potential of our technology for electro-driven, chemical-free lithium extraction from alternative sources.

Nanoarchitecture via Synchronic Stacking of Metallic and Nonmetallic Two-Dimensional Nanosheets for Optimal Light-Driven Ion Transport

The exceptional selectivity and responsive ion transport in biological channels inspire technology breakthrough in energy, environmental, and resource sectors. However, existing nanofluidic systems with a high photothermal conversion efficiency often exhibit excessive thermal conductivity, which impedes the creation of effective temperature gradients and results in a low ion transport efficiency. In this study, a strategy based on the synchronic stacking of metallic and nonmetallic two-dimensional (2D) nanosheets was presented to construct heterogeneous nanofluidic channels. This specific nanoconfined architecture sustained high temperatures in the illuminated area while maintaining low temperatures in the nonilluminated area, thus obtaining a robust driving force from sunlight for directional ion transport. As a result, our light-responsive ion transport system demonstrated significant potential in solar energy conversion and osmotic energy harvesting, surpassing those of all previously reported nanofluidic systems. Additionally, although it is still at the proof-of-concept stage, it shows great promise in light signal monitoring. This work provides an effective strategy for developing advanced light-responsive ion transport systems and their important applications.

Metal-organic framework-based membranes for ion separation/selection from salt lake brines and seawater

Nanofiltration (NF) technologies have evolved into a stage ready for industrial commercialization. NF membranes with unique separation characteristics are widely used for ion selection in water environments. Although many materials have been synthesized and functionalized for specific ion separation, the permeability-selectivity trade-off is still a major challenge. Metal-organic frameworks (MOFs), as a class of promising materials to meet industrial demands, are gaining increasing attention. Many experimental and theoretical studies have been conducted on the applications of MOF-based membranes in ion selection. This review focuses on MOF-based NF membranes for ion separation/selection from seawater and salt lake brines, including their applications in industry. First, a brief discussion on the development of membrane technology for ion selection is given, with the principles of ion separation via NF membranes, industrial implementations, and technical difficulties being discussed. Next, the benefits and challenges of using MOF membranes in NF processes are elaborated, including the basic properties of MOFs, approaches to fabricate MOF membranes for efficient ion selection and challenges in constructing industrially viable membranes. Finally, state-of-the-art studies on key characteristics of MOFs for NF membrane fabrication are presented. It indicates that the utilization of MOF-based membranes has significant potential to improve ion separation performance. However, the lack of sufficient data under industrial conditions highlights the need for further development in this area.

Eliminating the effect of pH: Dual-matrix modulation adsorbent enables efficient lithium extraction from concentrated seawater

Lithium ion sieve adsorbents frequently extract liquid lithium resources due to their adsorption effect and cost advantages. However, the adsorption effect is significantly influenced by the ambient pH. The pH effects on the adsorption process can be categorized into two main areas: the competition adsorption of impurity ions and the difference in surface zeta potential. A dual-matrix modulation adsorbent was prepared, comprising a carrier matrix modified with zwitterionic quaternary ammonium bases and an adsorption matrix modified with carboxylation. The zwitterionic quaternary ammonium base groups were employed to mitigate the competitive adsorption of impurity ions by acid-base neutralization. Furthermore, the negative charge of carboxyl groups was employed to diminish the discrepancy in surface zeta potential. The adsorption effect of the ion sieve adsorbent under natural conditions appeared to be significantly enhanced by the dual-matrix modulation, with the saturated adsorption capacity (28 mg/g) and adsorption selectivity (α(Li+/Mg2+)=24.23) being 6.3 and 7.8 times higher than that of the manganese-based adsorbent (HMO) under the same conditions, respectively. Moreover, the adsorption effect was found to be consistent with HMO under alkaline conditions. The results demonstrate that by optimizing the adsorption conditions of the adsorbent, the detrimental impact of pH on the adsorption process of lithium ion sieves can be eliminated.

Modulating the pore and electronic structure for targeted recovery of platinum: Accelerated kinetic and reinforced coordination

Adsorption for recovery of low-concentration platinum (Pt) from the complex composition of acidic digestates was challenging because of slow kinetic and poor affinity. It was expected to be overcome by the improvement of pore size distribution and adsorption site activity. Herein, a series of Prussian blue etchings (PBE) with porosity-rich and activity-high cyano (CN) was synthesized to recover low-concentration Pt. The N2 isotherm results showed that the pore structure evolved from mesoporous to microporous. The Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations results revealed that the modulation of electronic structure converted FeII to FeIII in [FeII(CN)6]4-. The coexistence of micro- and meso-pore structures provided channels to accelerate adsorption and ensured PtII enrichment. The regulation of Fe valence state activated CN, which reinforced the strength of coordination interaction between Pt and Fe-CN- at N-atom. The adsorption rate and maximum capacity of PBE1 were 4.4 and 2.5 times higher than those of PB, respectively, due to the dual efficacy of accelerated kinetic and reinforced coordination. This study systematically analyzes the pivotal role of pore and electronic structure modulation in adsorption kinetic and affinity, which provides a novel strategy for PtII targeted recovery.