Search Results (1,788)

Against the challenge of extreme lead (Pb) contamination (>15,000 ppm) in industrial polluted soils, where conventional agents fail to disrupt stable Pb–soil complexes—this study extends our prior cadmium (Cd) remediation research to validate amino acid ionic liquids (AAILs) for highly recalcitrant metals. Fifteen AAILs were screened via batch washing, with [Met][NO₃] (methionine-based) demonstrating the highest Pb removal efficiency. Single-factor optimization revealed that under the conditions of 0.8 mol/L, 6:1 liquid–soil ratio, 60 min, 85.4% Pb was removed from severely contaminated soil by [Met][NO₃]. Kinetic analysis using four common models showed that the second-order kinetic equation provided the best fit, indicating that Pb removal was predominantly driven by chemical reactions such as complexation or ion exchange. After washing, the contents of various Pb species were significantly reduced, thereby mitigating environmental risks. Notably, no substantial changes in soil texture were observed. However, a marked increase in organic matter content was detected, accompanied by decreases in soil pH and mineral element concentrations. Analysis of soil mineral composition, functional groups, and chemical speciation revealed that [Met][NO₃] primarily facilitated Pb removal through ion-exchange and coordination reactions. This study establishes [Met][NO₃] as a green agent with dual efficacy: it achieves high-efficiency remediation of severely Pb-contaminated soil while ensuring environmental sustainability, thus highlighting its potential for practical application. Full article

The mechanism of dolomite has been a major hotspot in geological research. However, most of the current studies mainly focus on single microorganisms and fail to fully consider the influence of marine microbial diversity on the precipitation of carbonate rock minerals. In this paper, two marine microorganisms (Bacillus sp. and Virgibacilus oceani), which can induce dolomite precipitation, were selected to induce dolomite precipitation in a culture solution that simulated the Mg²⁺/Ca²⁺ of modern oceans. Four systems were set up in this experiment, including the Bacillus sp. system, the Virgibacilus oceani system, the co-precipitation system (Bacillus sp. and Virgibacilus oceani), and the control system. The synergistic promotion of the dolomite was analyzed by comparing the changes in solution pH, ion consumption, morphology, mineralogical phase, and thermal stability in each experimental group. The experimental results show that the increase in pH value and the consumption of Mg²⁺ and Ca²⁺ in the coexistence of Bacillus sp. and Virgibacilus oceani are greater than those in the single microorganism system. The minerals induced by Bacillus sp. and Virgibacilus oceani were mostly small calcium carbonate particles and a small amount of proto-dolomite. However, the faster precipitation rates, larger particle diameters, higher proportion of proto-dolomite, and higher thermal stability of the calcium carbonate and proto-dolomite induced by the two microorganisms suggest that biomineralization facilitates the formation of stable dolomite and accelerates the precipitation of Mg²⁺ and Ca²⁺ for bioremediation purposes. Full article

Lithium has emerged as a critical element in contemporary society. It has been classified as an indispensable feedstock in the manufacture of lithium-ion batteries for electric mobility, portable electronics, and stationary energy storage systems, which are essential for the integration of intermittent renewable energy sources. This metal also has other industrial applications and is projected to support future developments in semiconductor and aerospace technology. However, the exponential growth in global Li demand driven by energy transition and technological innovation requires a resilient and sustainable supply chain where both technological and environmental challenges should be addressed. This review discusses and analyzes some of current challenges associated with the Li supply chain given a particular emphasis on its separation methods. First, statistics of the Li market and its applications are provided, including the main sources from which to recover Li and the environmental impact associated with conventional Li extraction techniques from mineral ores and salar brines. Different separation methods (e.g., solvent extraction, adsorption, ion exchange, membrane technology) to recover Li from different sources are reviewed. Recent advances and developments in these separation strategies are described, including a brief analysis of their main limitations and capabilities. The importance and potential of recycling strategies for end-of-life batteries and industrial residues are also highlighted. A perspective on the gaps to be resolved with the aim of consolidating the Li supply chain to support the energy transition agenda is provided in this review. Full article

Fluid inclusions, ubiquitously present within fluorite during diagenesis and mineralization, are released as inevitable ionic components in the pulp during mineral crushing and grinding. This study, grounded in geochemistry, combined microstructural analysis, spectroscopy, and X-ray computed tomography (X-CT) to investigate the morphology and petrographic characteristics of fluid inclusions in fluorite minerals. Building on this foundation, inductively coupled plasma optical emission spectrometry (ICP-OES) and ion chromatography (IC) were employed to analyze the release patterns of fluid inclusion components and their impact on fluorite flotation. The results reveal that fluid inclusions within fluorite are predominantly liquid-rich, two-phase (vapor-liquid) inclusions, exhibiting a spatial distribution density as high as 14.1%. Furthermore, fluid components are released during fluorite grinding, particularly homonymous Ca²⁺ ions, which significantly influence fluorite flotation behavior. Low concentrations of Ca²⁺ can activate fluorite flotation, whereas high concentrations of Ca²⁺ consume the collector (sodium oleate) in solution through competitive adsorption. This competition inhibits the adsorption of sodium oleate onto the fluorite mineral surface. The findings of this research provide theoretical support for in-depth studies on fluid inclusions in minerals and their effects on mineral flotation behavior, thereby facilitating the clean and efficient recovery of strategic fluorite mineral resources. Full article

This study explores the visible-light-driven photolysis of Ferrioxalate complexes for the degradation of Toluidine Blue (TB), a persistent phenothiazine dye, using a 1 L recirculating batch-loop photoreactor. The reactor system incorporated two tubular photochemical units (35 cm × 3 cm each) in series: the first equipped with an immersed blue fluorescent lamp (12 W, 30 cm-tube), and the second with dual external blue LED lamps (18 W total, 30 cm) encasing a double-walled glass cell. Continuous flow between the units was maintained via a peristaltic pump. Experimental investigations were used to evaluate the effects of key parameters such as Fe(III) and oxalate concentrations, initial TB load, pH, light source, flow rate, ligand type, dissolved gas type, external H₂O₂ addition, and the presence of various inorganic ions. The results demonstrate efficient dye degradation, with ~75% TB removal within 1 h under combined fluorescent and LED irradiation, where each reactor contributing comparably. The optimal performance was achieved at pH 4, with a 10 oxalate-to-Fe(III) molar ratio (1 mM:0.1 mM) and a flow rate of 25 mL s⁻¹. Among various ligands tested (oxalate, acetate, citrate, EDTA), oxalate proved to be the most effective. The presence and type of anions significantly influenced degradation efficiency due to their potential scavenging effects. Although the process achieved high dye removal, TOC analysis indicated only moderate mineralization, suggesting the accumulation of non-colored intermediates. External H₂O₂ addition moderately improved TOC removal, likely due to enhanced hydroxyl radical generation via the Fenton mechanism. These findings highlight the promise of Ferrioxalate-based photochemical systems under visible light for dye removal, while also emphasizing the need for further research into by-product identification, mineralization enhancement, and toxicity reduction to ensure safe effluent discharge. Full article

Low-salinity waterflooding (LSWF) enhances oil recovery at low cost in carbonate reservoirs, but its effectiveness requires the precise control of injected water chemistry and interaction with reservoir minerals. This study specifically investigates carbonated low-salinity waterflooding (CLSWF), where dissolved ${\mathrm{CO}}_2$ modulates geochemical processes. This study develops an integrated transport model coupling geochemical surface complexation modeling (SCM) with multiphase compositional dynamics to quantify wettability alteration during CLSWF. The framework combines PHREEQC-based equilibrium calculations of the Total Bond Product (TBP)—a wettability indicator derived from oil–calcite ionic bridging—with Corey-type relative permeability interpolation, resolved via COMSOL Multiphysics. Core flooding simulations, compared with experimental data from calcite systems at 100 ${}^{\circ }\mathrm{C}$ and 220 bar, reveal that magnesium ([${\mathrm{Mg}}^{2+}$]) and sulfate ([${\mathrm{SO}}_4^{2-}$]) concentrations modulate the TBP, reducing oil–rock adhesion under controlled low-salinity conditions. Parametric analysis demonstrates that acidic crude oils (TAN higher than 1 $\mathrm{m}$$\mathrm{g}$ KOH/$\mathrm{g}$) exhibit TBP values approximately $2.5 \mathrm{times}$ higher than those of sweet crudes, due to carboxylate–calcite bridging, while pH elevation (higher than 7.5) amplifies wettability shifts by promoting deprotonated ${\mathrm{-COO}}^{-}$ interactions. The model further identifies synergistic effects between ([${\mathrm{Mg}}^{2+}$]) (ranging from 50 to 200 mmol/kgw) and ([${\mathrm{SO}}_4^{2-}$]) (higher than 500 mmol/kgw), which reduce (${\mathrm{Ca}}^{2+}$)-mediated oil adhesion through competitive mineral surface binding. By correlating TBP with fractional flow dynamics, this framework could support the optimization of injection strategies in carbonate reservoirs, suggesting that ion-specific adjustments are more effective than bulk salinity reduction. Full article

Batteries are a cornerstone of modern technology that supports a wide range of applications including portable electronics, electric vehicles and large-scale energy storage for renewable power systems. Despite their widespread use, commercial Li-ion batteries are limited by the mineral resources of Li. The rapidly growing battery market demands alternative battery systems, such as non-alkali metal-ion batteries, that are capable of delivering comparative energy densities. In the meantime, improving the performance of the batteries via generating sustainable strategies has been broadly studied. Proteins, as re naturally evolved macromolecules that possess diverse structures and functional groups, have been demonstrated to be able to transport various metallic ions inside bio-organisms. Therefore, active studies have been carried out on the use of natural proteins (e.g., zein, soy, fibroin, bovine serum albumin, etc.) to enhance the electrochemical performance of non-alkali metal-ion batteries. This review provides a comprehensive summary of recent advances on the studies of protein-based strategies for non-alkali metal-ion batteries and outlines perspectives for future sustainable electrochemical energy storage systems. Full article

The persistence of pharmaceutical pollutants such as ciprofloxacin (CIP) in aquatic environments represents a critical environmental threat due to their potential to induce antimicrobial resistance. Photocatalysis using TiO₂-based materials offers a promising solution for their mineralization; however, the limited visible-light response of TiO₂ and charge carrier recombination restricts its overall efficiency. In this study, Nb-doped TiO₂ nanoparticles were synthesized via the sol–gel method, incorporating Nb⁵⁺, ions into the TiO₂ lattice to modulate the structural and electronic properties of TiO₂ to enhance its photocatalytic performance for CIP degradation under UV and visible irradiation. Comprehensive structural, morphological, and optical analyses revealed that Nb incorporation stabilizes the anatase phase, reduces particle size (from 21.42 nm to 10.29 nm), and induces a slight band gap widening (from 2.85 to 2.87 eV) due to the Burstein–Moss effect. Despite this blue shift, Nb-TiO₂ exhibited significantly improved photocatalytic activity under visible light, achieving 86% CIP degradation with a reaction rate 16 times higher than that of undoped TiO₂. This enhancement was attributed to improved charge separation and higher hydroxyl radical (^•OH) generation, driven by excess conduction band electrons introduced by Nb doping. Density Functional Theory (DFT) calculations further elucidated the electronic structure modifications responsible for this behavior, offering molecular-level insights into Nb dopant-induced property tuning. These findings demonstrate how targeted doping strategies can engineer multifunctional nanomaterials with superior photocatalytic efficiencies, especially under visible light, highlighting the synergy between experimental design and theoretical modeling for environmental applications. Full article

The Gabal Um Samra (GUS) compound intrusion in the Eastern Desert of Egypt consists of a co-magmatic series of syenogranite and alkali feldspar granite. Accessory minerals (e.g., zircon, monazite, allanite) are abundant. Geochemically, the GUS intrusion is a classic A-type granite. It is extensively fractionated, enriched in large ion lithophile elements and high field strength elements, and depleted in Ba, Sr, K, and Ti. Normalized rare earth element patterns are nearly flat, without any lanthanide tetrad anomalies, but with distinct negative Eu anomalies (Eu/Eu* = 0.14–0.22) due to feldspar fractionation. Paired Zr-Hf and Y-Ho element systematics indicate igneous rather than hydrothermal processes. The petrogenesis of the comparatively unaltered GUS intrusion offers an opportunity to refine the standard model for post-collisional felsic magmatism in the Neoproterozoic Arabian–Nubian Shield. It is explained by the partial melting of juvenile crust induced by lithospheric delamination, followed by extensive fractional crystallization. A quantitative mass-balance model shows that the granite varieties of the GUS intrusion plausibly represent liquids along a single liquid line of descent; but, if so, the more evolved, later pulses display anomalous enrichment in Rb, Nb, Ta, U, and REE. The most plausible source for this enrichment is the extraction of small-degree residual melts from earlier pulses and the mixing of the melts into the later pulses, an energetically favorable process we call “auto-assimilation”. A quantitative model shows that the residual liquid after 97.5% crystallization of the syenogranite can fit the major oxide and trace element data in the alkali feldspar granite if 0.07% by mass of this melt is added to the evolving system for each 1% crystal fractionation by mass. The GUS intrusion represents an example of moderate rare metal enrichment and concentration to sub-economic grade by auto-assimilation. Similar processes may affect intrusions that feature higher grade mineralization, but the evidence is often obscured by the extensive alteration of those deposits. Full article

This study aims to develop environmentally friendly soil-stabilization materials by investigating the synergistic enhancement mechanism of industrial by-product lignin fibers (LFs) and sodium sulfate (Na₂SO₄) on the mechanical and micro-structural properties of cement-stabilized soil. A systematic evaluation was conducted through unconfined compressive strength (UCS), splitting tensile strength, and capillary water absorption tests, supplemented by microscopic analyses including XRD and SEM. The results indicate that the optimal synergistic effect occurs at 1.0% LF and 0.10% Na₂SO₄, which increases UCS and splitting tensile strength by 9.23% and 18.37%, respectively, compared to cement-stabilized soil. Meanwhile, early strength development is accelerated. Microscopically, LF physically bridges soil particles, forming aggregates, reducing porosity, and enhancing cohesion. Chemically, Na₂SO₄ acts as an activator, accelerating cement hydration and stimulating pozzolanic reactions to form calcium aluminosilicate hydrate and gypsum, which fill pores and densify the matrix. The synergistic mechanism lies in Na₂SO₄ enhancing the interaction between the LFs and clay minerals through ion exchange, facilitating the formation of a stable spatial network structure that inhibits particle sliding and crack propagation. This technology offers substantial sustainability benefits by utilizing paper-making waste LF and low-cost Na₂SO₄ to improve soil strength, toughness, and impermeability. Full article

The TuguanZhai rare earth deposit in Tengchong, along with the Longan and Yingpanshan deposits in Longchuan, is a significant ion-adsorption type rare earth (iREE) deposit in Yunnan, China. Previous studies mainly focused on the geochemistry of residual regolith or the migration and enrichment mechanism of rare earth elements (REEs), but lacked systematic analysis of the protoliths. To constrain this deposit and its protolith rock, called Tuguanzhai granite, we systematically integrate petrology features, petrogeochemistry, zircon U-Pb date, and artificial heavy mineral separation (AHMS). Specifically, iREE-host granites include two main periods in this area: the Early Cretaceous (112.13 ± 0.75 Ma) and the Paleocene–Eocene (52.78 ± 0.28 Ma, 48.56 ± 0.19 Ma). The former includes three types of biotite monzogranite with different grain sizes, and the latter is mainly medium-grained biotite monzogranite with local mylonitization. Geochemical features show that these granites generally share high alkalinity compositions (w(K₂O + Na₂O): 7.15 to 12.75 wt%) and potassium contents (w(K₂O): 3.89 to 8.36 wt%). The mineralized granites exhibit significantly higher concentrations of the total REEs than non-mineralized granites, along with a strong enrichment of light REEs. Moreover, the results of AHMS reveal that the REE contents of apatite, allanite, and titanite in mineralized granites are 4.98, 1.29, and 1.90 times more abundant than in non-mineralized granites, respectively. Due to REEs being released from these REE-rich minerals in humid environments, there exists significant potential for iREE formation and exploration in the Early Cretaceous granites in western Yunnan. We innovatively propose the “abundance of easily leachable minerals” as a key indicator for iREE mineralization and exploration, having found it to be better than the traditional total REE contents. Full article

Strontium, a key trace element regulating bone development and cardiovascular function, has seen growing research interest in its groundwater accumulation and resource potential. The unique geological structure of the northern Lushan Mountain slope provides an ideal setting to investigate strontium migration and enrichment. We systematically collected 21 groundwater samples and analyzed strontium occurrence characteristics and formation mechanisms using hydrochemical analysis, PHREEQC simulations, Gibbs diagrams, and cation exchange adsorption models. Analysis revealed that 71.4% of samples (15 groups) exceeded the GB 8537-2018 standard (≥0.4 mg/L), significantly higher than typical groundwater systems. Spatial distribution showed marked geological differentiation: average strontium concentration in Cambrian-Ordovician fractured-karst water reached 2.79 mg/L (range: 0.207–12.41 mg/L), 109.8% higher than in bedrock fissure water (1.33 mg/L). Structural control was evident, with samples near fault zones exhibiting generally higher concentrations than non-fault areas. Multivariate statistics indicated significant positive correlations between Sr²⁺ and TDS, Na⁺, Ca²⁺, and SO₄²⁻, suggesting synergistic enrichment mechanisms. Hydrogeochemical simulations confirmed that multiphase leaching of strontium-bearing silicate rocks provides the primary source, while rock weathering-driven ion exchange reactions constitute the key enrichment mechanism. This study elucidates the structural-lithological coupling-controlled hydrogeochemical cycle of strontium, providing theoretical support for delineating high-quality mineral water targets and developing health-beneficial geo-resources in the Lushan region. Full article

Goethite, a ubiquitous Fe(III) oxyhydroxide mineral, typically occurs in very small particle sizes whose interfacial properties critically influence the fate and transport of ionic species in natural systems. The surface site density of synthetic goethite increases with particle size, resulting in enhanced adsorption capacity per unit area. In the first two parts of this study, we modeled the adsorption of protons, nitrate, As(V), Pb(II), Zn(II), and phosphate on goethite as a function of particle size, adsorbate concentration, pH, and ionic strength, using unified parameters within the CD-MUSIC framework. Here, we extend this work to characterize the interfacial behavior of carbonate in goethite suspensions, using a comprehensive dataset generated previously under both closed and open CO₂ system conditions. Carbonate oxyanions, prevalent in geochemical environments, exhibit competitive and complexation interactions with other ions and mineral surfaces. Although a bidentate bridging surface carbonate complex has been successful in previous modeling efforts on goethite, we found that the size of the carbonate moiety is too small and would require extreme octahedron bending of the goethite’s singly coordinated sites to accommodate this type of binding. Here, we propose a novel complex configuration that considers structural, physicochemical, and spectroscopic evidence. Optimal unified affinity constants and charge distribution parameters for this complex simulated all experimental data successfully, providing further validation of the CD-MUSIC model for describing relevant goethite/aqueous interfacial reactions. Full article

Rare earth elements (REYs) are crucial components of billions of products worldwide. Transitioning from foreign to domestic REY sources requires utilizing both primary (i.e., carbonatites, alkaline igneous rocks, pegmatites, skarn deposits) and secondary (unconventional) sources (i.e., ion-adsorption clays, placer deposits, weathered rock, black and/or oil shales). Coal and coal-bearing strata, promising secondary REY resources, are the focus of this study. Understanding REY mineral associations in unconventional resources is essential to quantifying resource volume and identifying viable mineral separation and processing techniques. Highly REY-enriched (>750 ppm) coal or mudstone samples from the Uinta Region, Utah, USA, were selected for scanning electron microscopy (SEM) analysis. Energy dispersive X-ray spectroscopy (EDS)-determined REY enrichment occurs in: (1) a silt-size fraction (5–30 μm) of monazite and xenotime REY-enriched grains, (2) a clay-size fraction (2–5 μm) of monazite REY-enriched grains dispersed in the clay-rich matrix, and (3) organically confined REY domains < 2 μm. Findings suggest possible REY enrichment from multiple sources, including: (1) detrital silt-size grains, (2) volcanic ash fall, largely in clay-size grains, and (3) organic REY uptake in the peat swamp depositional environment. Full article

Iron, an essential element for virtually all known organisms, serves not only as a micronutrient but also as an energy source for bacteria. Iron-oxidizing microorganisms mediate Fe(II) oxidation under diverse redox conditions, yielding amorphous iron (hydr)oxides or crystalline iron minerals. This globally significant biogeochemical process drives modern iron cycling across terrestrial and aquatic ecosystems. The resulting biomineralization not only produces secondary minerals but also effectively immobilizes heavy metals, offering a sustainable strategy for environmental remediation. This review systematically examines (1) the biogeochemical mechanisms and mineralogical signatures of Fe(II) oxidation by four distinct iron oxidizers: acidophilic aerobes (e.g., Acidithiobacillus), neutrophilic microaerophiles (e.g., Gallionella), nitrate-reducing anaerobes (e.g., Acidovorax), and anoxygenic phototrophs (e.g., Rhodobacter); (2) research advances in heavy metal immobilization by biogenic iron minerals: adsorption, coprecipitation, and structural incorporation; and (3) the impact of pH, temperature, organic matter, and coexisting ions on Fe(II) oxidation efficiency and iron mineral formation by iron-oxidizing bacteria. By characterizing iron-oxidizing bacterial species and their functional processes under varying pH and redox conditions, this study provides critical insights into microbial behaviors driving the evolution of acid mine drainage (AMD). Full article