Search Results (98)

Wastewater treatment plants (WWTPs) not only function as receivers of per- and polyfluoroalkyl substances (PFAS) from influent streams, but also act as PFAS contributors to the environment via effluent and sewage sludge, attributed to their strong adsorption affinity and resistance to conventional wastewater treatment processes. Thus, this review aims to comprehensively analyze the occurrence, adsorption mechanisms, and environmental fate of PFAS in sewage sludge, with a particular focus on their fate during traditional sludge disposal, namely, land application, landfill, and incineration. Long-chain perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) dominate in sewage sludge from worldwide WWTPs, with increasing prevalence of short-chain compounds. Adsorption of PFAS by sewage sludge is influenced by PFAS chain length and function group, pH, ionic strength, and organic matter. Enhanced adsorption is achieved under acidic conditions and with divalent cations. In terms of PFAS behavior in conventional sludge management, land application facilitates PFAS uptake by crops, leading to bioaccumulation in the food chain and potential human exposure. Prolonged exposure to PFAS via landfilling not only significantly alters soil microbial community structures, but also yields bacterial toxicity. Effective incineration typically requires temperatures above 850–1000 °C. Incomplete thermal decomposition releases toxic fluorinated by-products into the environment and generates persistent fluorinated radicals, which result in fluorinated compounds formation in further thermal treatment. In conclusion, this work highlights the significant accumulation and persistence of PFAS in sewage sludge and their concerning behavior during conventional sludge disposal. They underscore the necessity for advanced treatment technologies and managing their impact on the ecosystem. Full article

Groundwater is the principal source of drinking water in northern Ghana, where fluoride and nitrate are the major groundwater-quality concerns. Naturally elevated fluoride concentrations (>1.5 mg/L) have resulted in the closure of wells, while nitrate pollution regularly occurs in shallow aquifers due to lack of sanitation infrastructure and agricultural activities. Distinguishing natural from human-induced groundwater contamination is therefore essential for effective groundwater management. This study assessed groundwater quality with regard to fluoride enrichment and established lithology-specific natural background levels (NBLs) for major ions and selected trace elements using groundwater samples from 110 wells across three different lithologies in the Vea Catchment, northern Ghana. The results reveal high fluoride NBLs in a K-feldspar-rich granitoid formation (3.84 mg/L) and near-guideline concentrations in a hornblende–biotite tonalite (1.41 mg/L). Silicate weathering, lithology-dependent dissolution of fluorine-bearing minerals, and cation exchange were identified as the principal processes controlling groundwater chemistry and fluoride enrichment. Elevated NBLs of Sr, Li, Ba and SiO₂ in the K-feldspar-rich granitoids indicate enhanced water–rock interaction whereas relationships between nitrate and Cl⁻, Br⁻, and SO₄²⁻ suggest localized anthropogenic impacts. These findings demonstrate the value of lithology-specific NBLs for improving groundwater quality assessment and supporting groundwater resource management in crystalline basement aquifers. Full article

Conventional polydimethylsiloxane (PDMS)-based antifouling coatings, despite their inherent fouling-release capability, exhibit critically insufficient antifouling performance under static seawater conditions. Inspired by the synergistic physical–chemical defense strategy of sessile marine organisms, specifically sea anemones, which combine a physical mucus barrier with antimicrobial peptide secretion, the present work develops a multi-mechanism hybrid coating—designated as sea anemone-inspired fluorosilicone polyurethane—that integrates low-surface-energy physical antifouling and cationic antibacterial chemical antifouling. This coating system is constructed from silicone polyurethane (PDMS-PU), a cationic antibacterial moiety (PDMS-N⁺), and fluorinated functional monomers. Through systematic compositional optimization, an optimal formulation (P-4) is identified, which achieves a fracture elongation of 78.19%, a normal adhesion strength of approximately 2.5 MPa, a water contact angle of 120°, and a surface energy of 12.86 mN/m. Notably, its antibacterial rates against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) exceed 95%. The resultant coating uniquely synergizes low surface energy, potent antibacterial activity, excellent mechanical properties, and thermal stability, thereby enabling long-term and stable antifouling performance in static seawater environments. This work provides a crucial technological foundation for the engineering application and industrialization of green, durable marine antifouling coatings. Full article

Endogenous estrogens are implicated in carcinogenesis through both estrogen receptor-mediated cell proliferation and the direct genotoxicity of reactive metabolites. Oxidative metabolism of estrogens produces catechol estrogens that are further converted to electrophilic ortho-quinones capable of alkylating DNA. The prevailing model of mutagenesis proposes that these N3Ade and N7Gua adducts depurinate to form abasic sites that induce mutations initiating hormone-related cancers. However, the mutation spectrum observed in experimental data is inconsistent with this mechanism, and synthetic studies of estrogen-DNA adducts have relied on acidic conditions that artificially promote depurination, leaving stable N7-dG lesions poorly understood. To address this, we synthesized stable N7-dG catechol and estrone adducts using 2′-fluorinated deoxyguanosine, a modification that inhibits N-glycosidic bond cleavage. ROESY 2D NMR spectroscopy revealed through-space correlations consistent with a preferred anti-conformation in solution, supported by molecular modeling. Structural analysis suggests that these cationic aryl adducts likely preserve the Watson–Crick base pairing edge but may promote tautomerization capable of altering base pairing and generating G-to-A mutations. These findings provide the first synthesized stable models of N7-dG estrogen adducts and may support an alternative mechanism of estrogen-induced mutagenesis independent of depurination, enabling future biochemical investigations of related DNA repair and mutagenesis. Full article

The persilylated Si₃–Si₇ analogues of the C₃–C₇ aromatic molecules and ions with all hydrogen or all fluorine atoms at silicon have been calculated at high levels of theory, up to MP2/aug-cc-pVTZ for all species and CCSD/6-311++G** for Si₃ and Si₄ species, both in the gas phase and in a polar solvent (water). The aromaticity of the calculated species was estimated using structural, energetic, and NMR criteria. (SiF)₃⁺ cations are more aromatic than (SiH)₃⁺ by the NICS (nuclear-independent chemoical shift) but less aromatic by the ASE (aromatic stabilization energy) criterion. Dications (SiX)₄²⁺ are planar (X = H) or slightly puckered (X = F); the ASE decreases by 4–5 kcal/mol upon going from gas to solution, or from X = H to X = F. Dianions (SiX)₄²⁻are nonplanar and antiaromatic. The ASE for the slightly distorted-from-planarity anion Si₅H₅⁻ is ~53 kcal/mol, vs. 85 kcal/mol for its carbon analogue. The structure of Si₆X₆ molecules strongly depends on the level of calculations. The NICS and ASE values have been calculated for planar Si₆H₆ and (SiH)₇⁺ but not for strongly distorted Si₆F₆ and (SiF)₇⁺ species. Full article

Volatile coordination compounds are widely used as precursors for the gas phase synthesis of functional materials. However, such complexes are still very rare for alkali metals, especially for heavy representatives of this family (potassium, rubidium, cesium) due to the tendency to form polymeric structures. This work is devoted to the exploration of a potassium hexafluoroacetylacetonate complex with 18-crown-6 ether, K(18C6)(hfac), as a unique volatile precursor with an isolated molecular structure. A convenient synthesis procedure was developed, and key structural features were identified including temperature-dependent effects. The thermal properties of the complex were studied via thermogravimetry and measurements of saturated vapor pressure using the Knudsen effusion method with mass spectrometric registration of the gas phase composition. Both from solution and the gas phase, the molecular films of K(18C6)(hfac) obtained exhibit a strictly (h00) orientation, where half of the surface cations have a coordination sphere accessible to supramolecular contacts. For the first time, the possibility of producing potassium-containing films from a fluorinated precursor by metal–organic chemical vapor deposition (MOCVD) has been demonstrated. With oxygen as the reactant gas, potassium fluoride forms and interacts with the silicon substrate, while introducing water vapor significantly reduces the fluorine content, suggesting its suitability for the preparation of oxide films. Full article

Topaz is one of the most economically important fluorine-rich nesosilicates, which are predominantly colorless in natural crystals. Hence, the trade relies almost entirely on irradiated blue topaz with an unstable color center, which has been shown to fade over time. The cobalt (Co) diffusion treatment is a stable alternative process for converting colorless topaz to blue by a solid-state diffusion mechanism. To investigate the potential role of Co²⁺ substitution in the formation of the blue layer and the coupled behavior of F/OH dehydroxylation in facilitating this process, systematic diffusion treatments have been successfully conducted and compared. In this study, gem-quality topazes were annealed in air at 1000 °C for 20–40 h (hr) along with CoO, Fe₂O₃, Cr₂O₃, and CuO powders. The diffused products were characterized using Scanning Electron Microscope (SEM), Ultraviolet-Visible absorption spectroscopy (UV-Vis), Near-Mid Infrared spectroscopy (NMIR), and X-ray photoelectron spectroscopy (XPS). Parallel runs with CuO, Fe₂O₃, or Cr₂O₃ alone confirmed that none of these oxides produces a stable blue layer, underscoring the unique role of Co. The Co-diffused sample displays an intense blue layer characterized by a Co²⁺ octahedral isomorphism triplet at 540, 580, and 630 nm, which are absent from both untreated and heat-only controls. XPS analysis reveals the emergence of Co²⁺ (binding energy: 780.63 eV) and a concomitant depletion in F⁻, along with the disappearance of the OH overtone absorption at 7123 cm⁻¹. These observations confirm that defluorination generates octahedral vacancies accommodated by the coupled substitution: CoF₂ (solid reactant) + (AlO₂)⁻ (fragment of topaz structure) → AlOF (solid product) + (CoOF)⁻ (fragment of topaz structure). Prolonged annealing leads to decreased relative atomic percentages of K⁺ and F⁻ ions, consistent with volatilization losses during the high-temperature process, thereby directly correlating color intensity with cobalt valence state, which transfers from Co²⁺ to Co³⁺. These findings establish a Co-incorporation chronometer for F–rich aluminosilicate systems, with an optimal annealing time of approximately 20 hr at 1000 °C. Furthermore, the above results demonstrate that the color mechanism in nesosilicate gems is simultaneously governed by volatile release and cation availability. Full article

Metal anodes promise improvements in energy density and cost; however, their performance is determined within the first several nanometers at the interface. This review reports on how polymer-based artificial solid electrolyte interphases (SEIs) are engineered to stabilize Li and aqueous-Zn anodes, and how these designs are now evaluated against operando readouts rather than post-mortem snapshots. We group the related molecular strategies into three classes: (i) side-chain/ionomer chemistry (salt-philic, fluorinated, zwitterionic) to increase cation selectivity and manage local solvation; (ii) dynamic or covalently cross-linked networks to absorb microcracks and maintain coverage during plating/stripping; and (iii) polymer–ceramic hybrids that balance modulus, wetting, and ionic transport characteristics. We then benchmark these choices against metal-specific constraints—high reductive potential and inactive Li accumulation for Li, and pH, water activity, corrosion, and hydrogen evolution reaction (HER) for Zn—showing why a universal preparation method is unlikely. A central element is a system of design parameters and operando metrics that links material parameters to readouts collected under bias, including the nucleation overpotential (η_nuc), interfacial impedance (charge transfer resistance (R_ct)/SEI resistance (R_SEI)), morphology/roughness statistics from liquid-cell or cryogenic electron microscopy (Cryo-EM), stack swelling, and (for Li) inactive-Li inventory. By contrast, planar plating/stripping and HER suppression are primary success metrics for Zn. Finally, we outline parameters affecting these systems, including the use of lean electrolytes, the N/P ratio, high areal capacity/current density, and pouch-cell pressure uniformity, and discuss closed-loop workflows that couple molecular design with multimodal operando diagnostics. In this view, polymer artificial SEIs evolve from curated “recipes” into predictive, transferable interfaces, paving a path from coin-cell to prototype-level Li- and Zn-metal batteries. Full article

High-fluoride hot springs serve as a natural laboratory for investigating microbial adaptation and variations in community structure under extreme environments. This study utilized water chemistry analysis and 16S rRNA gene sequencing to investigate the correlation between high-fluoride hot springs and microbial community structure and diversity. The results show that the five hot springs exhibited an average F⁻ content of 15.04 mg/L, with weakly alkaline pH, high total dissolved solids, and Na⁺ as the dominant cation. The hydrochemical type was classified as HCO₃⋅SO₄-Na, consistent with the chemical characteristics of high-fluorine water. Microbial abundance and diversity were significantly reduced in the hot springs as compared to the surface water and groundwater samples. The dominant phyla in the study area included Pseudomonadota, Cyanobacteriota, Bacteroidota, and Actinomycetota. The genus-level composition varied significantly across samples, with no dominant genus observed universally. The specific genera present in different samples exhibit unique functional attributes, such as Tepidimonas, Rhodobacter, Hyphomonas, Parvibaculum, Polynucleobacter and Limnohabitans. Cluster analysis confirmed that dissimilarity coefficients highlight the significant influence of microbial abundance on inter-sample differences among hot springs. Redundancy analysis of the top 11 phyla by abundance in water samples revealed that the presence of F⁻ exerts inhibitory effects on microbial growth. Full article

Two single-crystal X-ray structure determinations of 2-aminopyrimidinium hydrogen tri oxofluorophosphate, (C₄H₆N₃)⁺·(HFO₃P)⁻, (I), and bis(2-aminopyrimidinium) trioxofluorophosphate, 2(C₄H₆N₃)⁺·(FO₃P)²⁻, (II), as well as their vibration spectra (FTIR on powder samples and the Raman spectra on unoriented single crystals) with a detailed assignment of vibrational modes are reported. The structure (I) consists of one independent 2-aminopyrimidinium cation and one hydrogen trioxofluorophosphate anion, while (II) consists of two symmetry independent 2-aminopyrimidinium cations and one trioxofluorophosphate anion. In (I), there is an O-H···O hydrogen bond of a moderate strength. A pair of these hydrogen bonds is situated about the symmetry centre and involved in the graph set motif R²₂(8). There are also N-H···O hydrogen bonds of a moderate strength, which are present in both structures while being involved in the graph set motifs R²₂(8), too. In addition, the N-H···O hydrogen bonds form R³₄(10) graph set motifs in (II). The latter motifs form ribbons which propagate parallel to the unit-cell axis a. In both structures, there are present π···π-electron ring interactions into which the primary amine groups are involved. In both structures, there are also present weak C-H···N hydrogen bonds with participation of the non-protonated ring N-atoms. The fluorine participates in the C-H···F hydrogen bonds in both title structures. The P-F distances are normal in both anions. The structure (I) differs from the known structure of 2-aminopyrimidinium hydrogen phosphite, the compositional isomer, though the main hydrogen bonds show similar geometry in both structures. The crystal of (I) was twinned. Full article

Supramolecular hydrogels formed by the self-assembly of low-molecular-weight (LMW) agents are promising next-generation biomaterials for drug delivery, tissue engineering, and regenerative medicine. Phenylalanine (Phe) derivatives have emerged as a privileged class of LMW supramolecular gelators due to their strong propensity to self-assemble into emergent hydrogel networks with demonstrated biocompatibility. We have previously reported a series of cationic Phe-derived gelators in which fluorenylmethoxycarbonyl (Fmoc) phenylalanine (Phe), 3-fluorophenylalanine (3F-Phe), and pentafluorophenylalanine (F₅-Phe) are functionalized at the C-terminus with diaminopropane (DAP). These gelators (Fmoc-Phe-DAP, Fmoc-3F-Phe-DAP, and Fmoc-F₅-Phe-DAP) are water-soluble and undergo spontaneous self-assembly and gelation upon an increase in the ionic strength of the solution caused by addition of sodium chloride. Herein, we report the effects of pH on the self-assembly and gelation of Fmoc-Phe-DAP, Fmoc-3F-Phe-DAP, and Fmoc-F₅-Phe-DAP. We also describe the effects that pH has on the emergent properties of these hydrogel networks, including assembly morphology and hydrogel viscoelasticity. These studies indicate that pH has varying effects on the properties of the hydrogels that are also dependent on the molecular structure of the Fmoc-Phe-DAP derivative. Fmoc-Phe-DAP hydrogels are highly sensitive to changes in solvent pH, forming strong hydrogels only near neutral pH. In contrast, hydrogels of Phe derivatives with fluorinated side chains (Fmoc-3F-Phe-DAP and Fmoc-F5-Phe-DAP) have consistent emergent viscoelastic properties across a wider range of acidic to basic pH values. Full article

To enhance the specific energy and rate performance of lithium primary batteries, the development of advanced cathode materials with superior electrochemical properties is essential. Fluorides, composed of light fluorine elements and multivalent cations, exhibit multi-electron reaction characteristics, possess a high theoretical voltage, and demonstrate high discharge-specific energy. However, owing to fluorine’s high electronegativity, which leads to the formation of strong ionic bonds with other elements, most fluorides exhibit poor electronic conductivity, thereby constraining their electrochemical performance when used as cathode materials. Copper fluoride (CuF₂) exhibits a high theoretical specific capacity and discharge voltage but is constrained by its large bandgap, poor electronic conductivity, and difficulties in synthesizing anhydrous CuF₂ materials, which significantly limit its electrochemical activity. In this study, zinc (Zn) was chosen as a dopant for copper fluoride. By combining theoretical calculations with experimental validation, the impacts of Zn doping on the structural stability and electrochemical performance of copper fluoride were comprehensively analyzed. The resultant highly active Zn-doped copper fluoride achieved a discharge specific capacity of 528.6 mAh/g at 0.1 C and 489.1 mAh/g at 1 C, showcasing superior discharge-specific energy and good rate performance. This material holds great potential as a promising cathode candidate for lithium batteries, providing both high specific energy and power density. Full article

Layered transition metal oxide (LTMO) cathode materials for sodium-ion batteries (SIBs) have attracted extensive attention due to their unique structural stability and excellent electrochemical performance. However, their poor stability in air has significantly impeded their practical application, as exposure to moisture and carbon dioxide can lead to Na⁺ loss, phase transitions, and decreased electrochemical performance. This paper reviews the application of high-entropy strategies in sodium-ion LTMO cathode materials, focusing on the optimization of air stability and electrochemical performance through approaches including high-entropy cation regulation, P2/O3 dual-phase synergistic structures, and fluorine ion doping. Studies have shown that high-entropy design can effectively inhibit phase transitions, alleviate Jahn–Teller distortion, enhance oxygen framework stability, and markedly enhance the cycle life and rate performance of materials. Furthermore, future research directions are proposed, including the use of advanced characterization techniques to reveal failure mechanisms, the integration of machine learning to optimize material design, and the development of high-performance mixed-phase structures. High-entropy strategies provide new perspectives for the development of SIBs cathode materials with enhanced air stability, potentially promoting the practical application of SIBs in large-scale energy storage systems. Full article

Carbon dioxide, the primary greenhouse gas responsible for global warming, represents today a critical environmental challenge for humans. Mitigating CO₂ emissions and other greenhouse gases is a pressing global concern. The primary goal of this study is to investigate the potential of particular ionic liquids (ILs) in capturing CO₂ for the sweetening of natural and other gases. The solubility of CO₂ was measured in three distinct ILs, which shared a common anion (triflate, TfO) but differed in their cations. The selected ionic liquids were {1-butyl-3-methylimidazolium triflate [BMIM][TfO], 1-butyl-1-methylpyrrolidinium triflate [BMP][TfO], and 1-butyl-4-methylpyridium triflate [MBPY][TfO]}. The solvents were screened based on results from a molecular computational study that predicted low CO₂ Henry’s Law constants. Solubility measurements were conducted at 303.15 K, 323.15 K, and 343.15 K and pressures up to 1.5 MPa using a gravimetric microbalance (IGA-003). The CO₂ experimental results were modeled using the Peng–Robinson Equation of state with three mixing rules: van der Waals one (vdWI), van der Waals two (vdWII), and the non-random two-liquid (NRTL) Wong–Sandler (WS) mixing rule. For the three ILs, the NRTL-WS mixing rule regressed the data with the lowest average deviation percentage of 1.24%. The three solvents had similar alkyl chains but slightly different polarities. [MBPY][TfO], with the largest size, exhibited the highest CO₂ solubility at all three temperatures. Calculation of its relative polarity descriptor (N) shows it was the least polar of the three ILs. Conversely, [BMP][TfO] showed the highest Henry’s Law constant (lowest solubility) across the studied temperature range. Comparing the results to published data, the study concludes that triflate-based ionic liquids with three fluorine atoms had lower capacity for CO₂ compared to bis(trifluoromethylsulfonyl) imide (Tf2N)-based ionic liquids with six fluorine atoms. Additionally, the study provided data on the enthalpy and entropy of absorption. A final comparison shows that the ILs had a lower CO₂ capacity than Selexol, a solvent widely used in commercial carbon capture operations. Compared to other ILs, the results confirm that the type of anion had a more significant impact on solubility than the cation. Full article

Single-phase white-light-emitting materials, particularly 2D hybrid organic–inorganic halide perovskites, have garnered significant attention due to their strong electron–phonon interactions, which lead to broad luminescence and a notable Stokes shift resulting from self-trapped exciton recombination. However, 2D lead iodide perovskites typically display these characteristics poorly, restricting their efficiency as white-light emitters. This study presents a 2D lead iodide perovskite that incorporates a fluorinated π-conjugated aggregation-induced enhanced emission luminophore, FPCSA, as a bulky organic cation to create a quasi-2D perovskite. The FPCSA cation establishes a Type II energy level alignment with the lead iodide layer in the 2D perovskite, and a significant energy offset effectively suppresses charge transfer, enabling independent emission from both the organic and inorganic layers while facilitating self-trapped exciton formation. Under 315 nm UV excitation, this material demonstrates warm white-light emission with RGB triple-band photoluminescence stemming from the electronically decoupled FPCSA and perovskite layers. These findings provide a promising new method for designing efficient single-phase white-light-emitting materials for optoelectronic applications. Full article