Search Results (293)

Kelp is a natural hydrogel material, which has been widely used in food industry. However, as a natural material, its properties have not been well explored. In this work, the surface and mechanical properties of kelp were investigated. The surface of kelp exhibited superoleophobicity and a self-clean property. The friction coefficient (COF) of the kelp surface was also low (<0.1). Interestingly, kelp demonstrated anisotropic mechanical properties either with or without metal ions. The tensile strength and toughness of kelp along with the growth direction (H) were better than those at the direction vertical to the growth direction (V). The adsorption of metal ions would significantly enhance the mechanical properties and ionic conductivity. Triboelectric nanogenerator (TENG) was assembled using kelp with NaCl, which showed excellent output performance (open-circuit voltage of 30 V, short-circuit current of 0.73 μA and charge transfer on contact of 10.5 nC). A writing tablet was prepared to use as the kelp-based self-powered tactile sensor. This work provides a new insight into natural kelp, which may be used as a renewable material. Full article

Recent research on the design and synthesis of new and upgraded materials for secondary batteries is growing to fulfill future energy demands around the globe. Herein, by using DFT calculations, the thermodynamic and electrochemical properties of Na/Na⁺@C₁₂ complexes and then halogens (X⁻ = Br⁻, Cl⁻, and F⁻) as counter anions are studied for the enhancement of Na-ion battery cell voltage and overall performance. Isolated C₁₂ nanorings showed a lower cell voltage (−1.32 V), which was significantly increased after adsorption with halide anions as counter anions. Adsorption of halides increased the Gibbs free energy, which in turn resulted in higher cell voltage. Cell voltage increased with the increasing electronegativity of the halide anion. The Gibbs free energy of Br⁻@C₁₂ was −52.36 kcal·mol⁻¹, corresponding to a desirable cell voltage of 2.27 V, making it suitable for use as an anode in sodium-ion batteries. The estimated cell voltage of these considered complexes ensures the effective use of these complexes in sodium-ion secondary batteries. Full article

The treatment of contaminants from road infrastructure poses significant challenges due to their variable composition and the high concentrations of chloride ions, heavy metals, and oil-derived substances. Traditional methods for protecting groundwater environments are often insufficient. A promising alternative is permeable reactive barrier (PRB) technology, which utilizes recycled materials and construction waste as reactive components within the treatment zone of the ground. This paper delves into the potential of employing a composite (MIX) consisting of modified construction aggregate (as recycled material) and activated carbon (example of reactive material) to address environmental contamination from a mixture of heavy metals and chloride. The research involved chemical modifications of the road aggregate, activated carbon, and their composite, followed by laboratory tests in glass reactors and non-flow batch tests to evaluate the kinetics and chemical equilibrium of the reactions. The adsorption process was stable and conformed to the pseudo-second-order kinetics and Langmuir, Toth, and Redlich–Peterson isotherm models. Studies using MIX from a heavy metal model solution showed that monolayer adsorption was a key mechanism for removing heavy metals, with strong fits to the Langmuir (R² > 0.80) and Freundlich models, and optimal efficiencies for Cd and Ni (R² > 0.90). The best fit, at Cd, Cu, Ni = 0.96, however, was with the Redlich–Peterson isotherm, indicating a mix of physical and chemical adsorption on heterogeneous surfaces. The Toth model was significant for all analytes, fitting Cl and Cd well and Pb and Zn moderately. The modifications made to the composite significantly enhanced its effectiveness in removing the contaminant mixture. The test results demonstrated an average reduction of chloride by 85%, along with substantial removals of heavy metals: lead (Pb) by 90%, cadmium (Cd) by 86%, nickel (Ni) by 85%, copper (Cu) by 81%, and zinc (Zn) by 79%. Further research should focus on the removal of other contaminants and the optimization of magnesium oxide (MgO) dosage. Full article

The use of chloride-based deicing salts, particularly sodium chloride (NaCl) and calcium chloride (CaCl₂), is a common practice in cold regions for maintaining road safety during winter. However, the accumulation of salt residues in adjacent soils poses serious environmental threats, including reduced pH, increased electrical conductivity (EC), disrupted soil structure, and plant growth inhibition. This study aimed to evaluate the combined effect of activated carbon (AC) and Pennisetum alopecuroides, a salt-tolerant perennial grass, in alleviating salinity stress under deicer-treated soils. A factorial greenhouse experiment was conducted using three fixed factors: (i) presence or absence of Pennisetum alopecuroides, (ii) deicer type (NaCl or CaCl₂), and (iii) activated carbon mixing ratio (0, 1, 2, 5, and 10%). Soil pH, EC, and ion concentrations (Na⁺, Cl⁻, Ca²⁺) were measured, along with six plant growth indicators. The results showed that increasing AC concentrations significantly increased pH and reduced EC and ion accumulation, with the 5% AC treatment being optimal in both deicer systems. Plant physiological responses were improved in AC-amended soils, especially under CaCl₂ treatment, indicating less ion toxicity and better root zone conditions. The interaction effects between AC, deicer type, and plant presence were statistically significant (p < 0.05), supporting a synergistic remediation mechanism involving both adsorption and biological uptake. Despite the limitations of short-term controlled conditions, this study offers a promising phytomanagement strategy using natural adsorbents and salt-tolerant plants for sustainable remediation of salt-affected soils in road-adjacent and urban environments. Full article

As the crucial current collector for lithium-ion batteries (LIBs), electrolytic copper foils are generally manufactured by electrodeposition in acidic copper sulfate solution. However, there are many disadvantages for traditional electrolytic copper foils, such as coarse grains, insufficient mechanical properties, and high energy consumption. In order to improve the performances of electrolytic copper foil, a novel cuprous electrodeposition system was developed in this study. A soluble cuprous coordination compound was synthesized. In addition, XPS, FT-IR spectrum, as well as single-crystal X-ray diffraction illustrated that thiourea coordinated with Cu(I) through S atom and therefore stabilized Cu(I) by the formation of CuCl·3TU. Importantly, the corresponding electrochemical behaviors were investigated. In aqueous solution, two distinct reduction processes were demonstrated by linear sweep voltammetry (LSV) at rather negative potentials, including the reduction of adsorbed state and non-adsorbed state. Moreover, the observed inductive loops in electrochemical impedance spectroscopy further confirmed the adsorption phenomenon. More significantly, the designed cuprous electrodeposition system could contribute to low energy consumptions during electrolysis. and produce ultrathin nanocrystalline copper foils with appropriate roughness. Consequently, the electrolysis method based on CuCl·3TU could provide an improved approach for copper foils manufacturing in advanced LIBs fabrication. Full article

This study investigates the effects of NaCl activation on the structural and chemical properties of kaolin for the adsorption of Zn²⁺ from solution. Kaolin was treated with NaCl solution at varying concentrations (0.5, 1.0, 2.0, and 4.0 M), and ultrasonication was used as a means of agitation. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS) were employed to characterize the physical and chemical effects of the NaCl activation and its subsequent influence on the kaolin’s heavy metal removal efficiency. The kaolin activated with 0.5 M NaCl solution yielded the optimal performance with a 13% increase in Zn²⁺ removal compared to the unmodified clay. The adsorption data best matched the pseudo-second-order kinetic model and the Langmuir isotherm. This indicates a monolayer adsorption on a homogeneous surface, with chemisorption as the dominant adsorption mechanism. Thermodynamic analysis also revealed that the adsorption process was endothermic and spontaneous. Furthermore, NaCl activation slightly enhanced the microstructural properties of the kaolin and moderated the surface charge, creating a more favorable electrostatic environment for improved heavy metal ion adsorption. The findings further highlight the potential of NaCl activation to introduce exchangeable Na⁺ onto the kaolin surface in a pH-neutral environment and promise a clean, mechanistically clear, and practical route for ion exchange with heavy metals such as Zn²⁺. Full article

As China’s primary grain-producing area, the Luxi Plain is rich in groundwater resources, which serves as the main water supply source in this region. Investigating the evolution of hydrochemical characteristics and influencing factors of groundwater in this region is crucial for maintaining the safety of groundwater quality and ensuring the high-quality development of the water supply. This study took Liaocheng City in the hinterland of the Luxi Plain as the study area. To clarify the hydrochemical characteristics evolution trend of groundwater in the area, the hydrochemical characteristics of shallow groundwater in recent years were systematically analyzed. The methods of ion ratio, correlation analysis, Gibbs and Gaillardet endmember diagrams, as well as the application of the absolute principal component scores–multiple linear regression (APCS-MLR) receptor model were used to determine the contribution rates of different ion sources to groundwater and to elucidate the driving factors behind the evolution of groundwater chemistry. Results showed significant spatiotemporal variations in the concentrations of major ions such as Na⁺, SO₄²⁻, and Cl⁻ in groundwater in the study area, and these variations demonstrated an overall increasing trend. Notably, the increases in total hardness (THRD), SO₄⁻, and Cl⁻ concentrations were particularly pronounced, while the variations in Na⁺, Mg²⁺, Ca²⁺ and other ions were relatively gradual. APCS-MLR receptor model analysis revealed that the ions such as Na⁺, Ca²⁺, Mg²⁺, SO₄²⁻, Cl⁻, HCO₃⁻ and NO₃⁻ all have a significant influence on the hydrochemical composition of groundwater due to the high absolute principal component scores of them. The hydrochemical characteristics of groundwater in the study area were controlled by multiple processes, including evaporites, silicates and carbonates weathering, evaporation-concentration, cation alternating adsorption and human activities. Among the natural driving factors, rock weathering had a greater influence on the evolution of groundwater hydrochemical characteristics. Moreover, mining activities were the most important anthropogenic factor, followed by agricultural activities and living activities. Full article

Contact electrification (CE), or triboelectrification, is an electron transfer phenomenon occurring at the interface between dissimilar materials due to differences in polarity, holding significant research value in tribology. The microscopic mechanisms of CE remain unclear due to the complex coupling of multiple physical processes. Recently, with the rise of triboelectric nanogenerator (TENG) technology, solid–liquid contact electrification has demonstrated vast application potential, sparking considerable interest in its underlying mechanisms. Emerging experimental evidence indicates that at water–polymer CE interfaces, the process involves not only traditional ion adsorption but also electron transfer. Halogen-containing functional groups in the solid material significantly enhance the CE effect. To elucidate the microscopic mechanism of water–polymer CE, this study employed first-principles density functional theory (DFT) calculations, simulating the interfacial electrification process using unit cell models of water contacting polymers. We systematically and quantitatively investigated the charge transfer characteristics at interfaces between water and three representative polymers with similar backbones but different halogen-functionalized (F, Cl) side chains: fluorinated ethylene propylene (FEP), polyvinyl chloride (PVC), and polytetrafluoroethylene (PTFE), focusing on evaluating halogen’s influence and mechanism on interfacial electron transfer. The results reveal that electron transfer is primarily governed by the energy levels of the polymer’s lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO). Halogen functional groups modulate the material’s electron-donating/accepting capabilities by altering these frontier orbital energy levels. Consequently, we propose that the critical strategy for polymer chemical modification resides in lowering the LUMO energy level of electron-accepting materials. This study provides a novel theoretical insight into the charge transfer mechanism at solid–liquid interfaces, offers guidance for designing high-performance TENG interfacial materials, and holds significant importance for both the fundamental theory and the development of advanced energy devices. Full article

The southeastern Hainan Island boasts abundant hydrothermal resources, most of which are exposed as thermal springs. Analyzing the hydrochemical characteristics, hydrochemical evolutionary mechanisms, and material transition of these resources is significant for their exploitation and utilization. This study investigated the Nanping geothermal field in southeastern Hainan Island, using five groups of geothermal water samples collected in 2022, as well as seven groups of geothermal water samples, one group of shallow groundwater samples, and one group of surface water samples taken in 2023. Specifically, this study examined water–rock interactions in the geothermal field using the Gibbs model, ion ratios, chloro-alkaline indices (CAIs), and the sodium adsorption ratio (SAR). Moreover, the mineral transfer process in groundwater was analyzed using inverse hydrogeochemical simulation. The results indicate that in the study area the geothermal water temperatures range from 64 °C to 80 °C, pH values from 8.32 to 8.64, and TDS concentrations from 431 mg/L to 623 mg/L. The primary hydrochemical types of geothermal water in the study area include Cl-Na and Cl·HCO₃-Na, suggesting low-temperature, slightly alkaline geothermal water. The hydrochemical components of geothermal water in the study area are primarily affected by water–rock interactions. Besides the dissolution of silicate minerals and halite, cation exchange reactions contribute greatly to the formation of Na⁺ and K⁺ in geothermal water. Geothermal water receives recharge from the atmospheric precipitation of the Diaoluo Shan area in the northwest of the study area, with the recharge elevation ranging from 967 to 1115 m. The inverse hydrogeochemical simulation results reveal that during the water–rock interactions, silicate minerals, clay minerals, gypsum, and halite dissolve, while quartz and carbonate minerals precipitate. Additionally, these processes are accompanied by cation exchange reactions dominated by the replacement of Na⁺ in surrounding rocks by Ca²⁺ in geothermal water. This study can provide a geological basis for the exploitation, utilization, and management of the Nanping geothermal field. Full article

Magnesium alloys are lightweight metals but suffer from high corrosion susceptibility due to their chemical reactivity, limiting their large-scale applications. To enhance corrosion resistance, this work combines Li–Al layered double hydroxides (LDHs) with triethylenetetramine (TETA) inhibitors to form an efficient corrosion protection system. Electrochemical tests, SEM, FT-IR, XPS, and 3D depth-of-field microscopy were employed to evaluate TETA-modified Li–Al LDH coatings at varying concentrations. Among them, the Li–Al LDHs without the addition of a TETA corrosion inhibitor decreased significantly at |Z|_{0.01 Hz} after immersion for 4 h. However, the Li–Al LDHs coating of 23.5 mM TETA experienced a sudden drop at |Z|_{0.01 Hz} after holding for about 60 h, and the Li–Al LDHs coating of 70.5 mM TETA also experienced a sudden drop at |Z|_{0.01 Hz} after holding for about 132 h. By contrast, at the optimal concentration (47 mM), after 24 h of immersion, the maximum |Z|_{0.01 Hz} reached 7.56 × 10⁵ Ω∙cm²—three orders of magnitude higher than pure Li–Al LDH coated AZ31 (2.55 × 10² Ω∙cm²). After 300 h of immersion, the low-frequency impedance remained above 10⁵ Ω∙cm², demonstrating superior long-term protection. TETA modification significantly improved the durability of Li–Al LDHs coatings, addressing the short-term protection limitation of standalone Li–Al LDHs. Li–Al LDHs themselves have a layered structure and effectively capture corrosive Cl⁻ ions in the environment through ion exchange capacity, reducing the corrosion of the interface. Furthermore, TETA exhibits strong adsorption on Li–Al LDHs layers, particularly at coating defects, enabling rapid barrier formation. This inorganic–organic hybrid design achieves defect compensation and enhanced protective barriers. Full article

This study examines the formation of the clay mineral simonkolleite (Skl) in bentonites contaminated with zinc(II) chloride (ZnCl₂), a process that has been little documented in heterogeneous systems such as contaminated bentonites. We explain the contamination mechanisms and provide new insights into the mineralogical, structural, and physicochemical transformations occurring within these materials. The objective, explored for the first time, was to assess how the ZnCl₂-induced mineral phase formation influences the properties of bentonites used as sealing materials, particularly regarding changes in specific surface area and porosity. Three bentonites were analyzed: Ca-bentonite from Texas (STx-1b), Na-bentonite from Wyoming (SWy-3), and Ca-bentonite from Jelsovy Potok, Slovakia (BSvk). Treatment with ZnCl₂ solution led to ion exchange and the formation of up to ~30% simonkolleite, accompanied by a concurrent decrease in montmorillonite content by 9–30%. A suite of analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray fluorescence (XRF), and energy-dispersive X-ray spectroscopy (EDS), was employed to characterize these transformations. The contamination mechanism of ZnCl₂ involves an ion exchange of Zn²⁺ within the montmorillonite structure, the partial degradation of specific montmorillonite phases, and the formation of a secondary phase, simonkolleite. These transformations caused a ~50% decrease in specific surface area and porosity as measured by the Brunauer–Emmett–Teller (BET) nitrogen adsorption and Barrett–Joyner–Halenda (BJH) methods. The findings raise concerns regarding the long-term performance of bentonite-based barriers. Further research should evaluate hydraulic conductivity, mechanical strength, and the design of modified bentonite materials with improved resistance to Zn-induced alterations. Full article

This study focuses on assessing the hydrogeochemical characteristics and irrigation suitability of groundwater in the Ras El Aioun and Merouana districts, using an integrated approach that combines physicochemical analysis, machine learning (ML), and Geographic Information Systems (GISs). Thirty groundwater samples were collected in June 2023 and subjected to extensive analyses, including major ions (Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO₃⁻, Cl⁻, SO₄²⁻), pH, TDS, alkalinity, and hardness. Hydrochemical facies analysis revealed that the Ca-HCO₃ type was dominant (93.33%), with some samples exceeding FAO limits, particularly for Na⁺, K⁺, SO₄²⁻, Cl⁻, Mg²⁺, and HCO₃⁻. Assessment of groundwater irrigation suitability revealed generally favorable conditions based on three key parameters: all samples (100%) were classified as excellent based on the Sodium Adsorption Ratio (SAR < 10), 70% showed good-to-permissible status by Sodium Percentage (Na% < 60), and 83.3% were within safe limits for Residual Sodium Carbonate (RSC < 1.25 meq/L). However, the Permeability Index (PI > 75%) categorized 96.7% of samples as unsuitable for long-term irrigation due to potential soil permeability reduction. Additionally, Total Hardness (TH < 75 mg/L) indicated predominantly soft water characteristics (90% of samples), particularly in the central study area, suggesting possible limitations for certain agricultural applications that require mineral-rich water. GIS-based spatial analysis showed that irrigation suitability was higher in the eastern and western regions than in the central zone. Advanced machine learning algorithms provide superior predictive capability for water quality parameters by effectively modeling complex, non-linear feature interactions that conventional statistical approaches frequently fail to capture. Three ML models—Support Vector Regression (SVR), Random Forest (RF), and Extreme Gradient Boosting (XGBoost)—were used to predict the Irrigation Water Quality Index (IWQI). XGBoost outperformed the others (RMSE = 2.83, R² = 0.957), followed by RF (RMSE = 3.12, R² = 0.93) and SVR (RMSE = 3.45, R² = 0.92). Integrating ML and GIS improved groundwater quality assessment and provided a robust framework for sustainable irrigation management. These findings provide critical insights for optimizing agricultural water use in water-scarce regions. Full article

This study used widely available waste biomass, corn cob (CC), to remove Pb ions from aqueous solutions. A two-step conversion of this material was carried out to improve its adsorption characteristics. Firstly, CC was prepared by hydrothermal carbonization; afterward, the obtained hydrochar was doped by MgCl₂ and pyrolyzed. The synthesized hydro-pyrochar (HCC-Mg) was used for adsorption experiments in a batch system. The surface and structural properties of HCC-Mg were characterized by SEM-EDX and FTIR analysis before and after Pb adsorption. Kinetic and isotherm models were applied to the experimental results. It was confirmed that Pb adsorption on HCC-Mg occurred rapidly, with a maximum adsorption capacity of 87.08 mg/g. The pseudo-second-order model best described the adsorption process, while the best fit of the experimental data was observed with the Sips isotherm model. The results of this study showed that the capacity of the synthesized HCC-Mg material had increased more than 14 times compared with raw CC. In addition, the synthesized material had the potential to be reused for at least five cycles with minimal loss of adsorption capacity and efficiency. Moreover, the results confirmed that HCC-Mg can be used as an efficient, sustainable adsorbent of Pb from polluted water. Full article

Olive mill wastewater (OMW) is deemed a substantial environmental pollutant, particularly in Mediterranean regions. Lower and middle-income countries, including Jordan, suffer from water scarcity and increasing demand for water, especially for drinking and irrigation purposes. Subsequently, the management and treatment of OMW represents a major concern. This study investigates the feasibility of utilizing Jordanian kaolinite as a simple, readily available, green, and sustainable adsorbent to mitigate the environmental impact of untreated or partially treated OMW. In this work, purified kaolinite (PK) was activated with sodium ions at room temperature. The characterization of PK and sodium-activated kaolinite (PK-NaCl) was accomplished using FTIR, XRD, TGA, and BET surface area analyses. The adsorption performance of both PK and PK-NaCl for OMW treatment were evaluated through batch and column experiments. The key physiochemical parameters of OMW were systematically analyzed in all influent and effluent samples to evaluate the treatment efficiency. In all cases, sodium-activated kaolinite significantly enhances treatment efficiency. The adsorption of total phenolic compounds (TPCs) onto both PK and PK-NaCl adsorbents was studied with respect to initial concentration, adsorbent dosage, and temperature. The maximum adsorption capacity was 8.88 mg/g for PK-NaCl, which was higher than that of PK, at an adsorbent dose of 1.0 g and a temperature of 323 K. The Langmuir and Freundlich isotherm models to describe the adsorption equilibrium were implemented, and both displayed good fit with the experimental data. Additionally, the removal efficiencies of heavy metal (i.e., Zn, Fe and Mn) ions were also evaluated. The findings demonstrated that the PK-NaCl completely removed all tested heavy metal ions, regardless of their initial concentrations. Therefore, the cost-effective and easily prepared PK-NaCl significantly improved the adsorption capacity and presents a promising treatment solution for OMW. This approach could be highly beneficial for olive mills across the Mediterranean regions to mitigate the environmental impact of OM waste. Full article

This study presents a novel ion-imprinted fiber material, I-(PP-g-GMA-NMDG), designed for the rapid and selective adsorption of borate ions. Leveraging low-temperature plasma graft polymerization, polypropylene (PP) melt-blown fibers were functionalized with glycidyl methacrylate (GMA) and N-methyl-D-glucamine (NMDG) to introduce tailored recognition sites. Systematic optimization of plasma parameters (100 W discharge power, O₂ atmosphere) and liquid-phase grafting conditions (28.5% GMA, 85 °C, 2.5 h) achieved a grafting rate of 203.26%. The imprinted fibers exhibited exceptional adsorption performance, with a maximum capacity of 35.85 mg/g at pH 9, reaching 90% saturation within 60 min. Adsorption kinetics adhered to a pseudo-second-order model, while the Freundlich isotherm indicated multilayer adsorption. Competitive ion experiments demonstrated high selectivity for B(OH)₄⁻ over anions (SO₄²⁻ and Cl⁻) and cations (Na⁺, K⁺, Ca²⁺, and Mg²⁺), which was attributed to the precise spatial and charge complementarity of the imprinted cavities. Characterization via FT-IR, XRD, and SEM confirmed successful synthesis and structural stability. The material retained 78.1% adsorption efficiency after five regeneration cycles, showcasing its practicality for boron recovery from wastewater. This work advances boron-selective adsorption technology by combining plasma modification with ion imprinting, offering a sustainable solution for industrial and environmental applications. Full article