Search Results (14,333)

Silicon (Si)–containing compounds, such as silica (SiO₂), play a crucial role as fillers, binding phases, and linking agents in sustainable materials. Coating biochar with SiO₂ can enhance its performance as a carbon-negative filler in composites such as bioplastics, rubber, asphalt, and cement, making it more competitive with conventional fillers. Biochar, derived from biomass pyrolysis, contains a high concentration of biogenic SiO₂—typically 50–80% of its total inorganic content. However, conventional extraction methods such as solvent extraction or gasification detach SiO₂ from the biochar matrix, leading to energy-intensive and environmentally unfavorable processes. The objective of this study was to develop an environmentally friendly and energy-efficient approach to induce the migration of embedded biogenic SiO₂ from within biochar to its surface—without detachment—using ultrasonic treatment. Fifteen biochar samples were produced by pyrolyzing five biomass types (sugarcane bagasse, miscanthus, wheat straw, corn stover, and railroad ties) at 650, 750, and 850 °C. Each sample was subsequently subjected to ultrasonic irradiation in an isopropanol–water mixture for 1 and 2 min. Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) analyses confirmed that ultrasound treatment significantly enhanced SiO₂ migration to the biochar surface, with up to a 2.5-fold increase in surface Si and O concentrations after 2 min of sonication. The effect was most pronounced for biochar synthesized at 850 °C, corresponding to higher surface porosity and structural stability. Fourier Transform Infrared (FTIR) spectroscopy revealed an increased intensity of the Si–O–Si asymmetric stretching band at 1030 cm⁻¹, indicating surface enrichment of siloxane networks and rearrangement of Si-containing functional groups. Overall, the results demonstrate that ultrasound-assisted treatment is a viable and sustainable technique for enhancing SiO₂ surface concentration and modifying the surface chemistry of biochar. This SiO₂-enriched biochar shows potential for advanced applications in soil amendment, CO₂ capture, water purification, and as a reactive additive in cementitious and asphalt composites. Full article

The textile industry releases effluents containing toxic contaminants such as azo dyes, which severely affect water quality and aquatic ecosystems. This study optimized the Fe⁰/H₂O₂/UV photo-Fenton process through Response Surface Methodology (RSM) using a Box–Behnken design applied to real textile wastewater. The process relies on in situ hydroxyl radicals (•OH) generation, which degrades refractory organic compounds. Under optimal conditions (pH 3.5, 0.5 g Fe⁰, and 0.55 mL H₂O₂), the system achieved complete color removal, 91% aromatic structures degradation, and an 80% COD reduction within 3 h. Statistical validation indicated an excellent model fit (R² = 1.0; Q² = 1.0), with strong correlation between experimental and predicted results. Spectroscopic analyses (UV–Vis and FTIR) further confirmed the cleavage of chromophoric and aromatic structures, indicating efficient pollutant degradation. Overall, the findings indicate that the Fe⁰/H₂O₂/UV system is an effective and sustainable technology for treating textile wastewater, offering strong potential for industrial-scale application. Full article

This paper reports an assessment of the photocatalytic activity of TiO₂ nanotubes (TNTs) doped with strontium titanate (SrTiO₃) and sulfur (S) with respect to the decomposition of methylene blue (MB). TNT was obtained by the double anodizing method with further doping of strontium titanate by the hydrothermal method and additional annealing in an atmosphere of N₂ (95%) + H₂S (5%) at 450–550 °C. The photocatalytic activity was evaluated using MB as a pollutant and this study was conducted using an Osram Vita-Lux lamp with a power of 300W as a visible light source. The photocatalytic abilities of the synthesized materials were investigated, and characterized by methods such as SEM, TEM, XRD, EDS, and UV–Vis spectroscopy. Our study showed that the SrTiO₃/TiO₂NT@S composite has a better photocatalytic decomposition ability for the dye under consideration compared to pure TNT and SrTiO₃/TiO₂NT. These results clearly demonstrate the potential of synthesized SrTiO₃/TiO₂NT@S material for applications in water purification and photocatalysis. Full article

The photocatalytic reduction of CO₂ in aqueous media offers a sustainable route for solar-to-fuel conversion, yet remains challenged by CO₂’s thermodynamic stability and kinetic inertness, low solubility, and competitive hydrogen evolution. Here, we investigate the interplay between ionic liquids (ILs), photocatalyst supports, and additive composition in directing product selectivity among CO, CH₄, and H₂. Using imidazolium acetate as a benchmark, we demonstrate that ILs not only pre-activate CO₂ but can also undergo decomposition pathways under illumination, notably Kolbe-type reactions leading to methane formation from acetate rather than from CO₂. Comparative studies of Pd-decorated TiO₂ and g-C₃N₄ nanosheets reveal distinct behaviors driven by their interfacial interactions with the imidazolim-based ionic liquid: weak interaction with TiO₂ strongly promotes hydrogen evolution, whereas strong coupling with g-C₃N₄ synergizes with C₁C₄ImOAc to trigger acetate-derived Kolbe reactivity. The systematic evaluation of alternative salts confirms the determinant role of anion basicity and medium-pH-basic anions facilitate CO₂ activation, whereas weakly basic or non-coordinating anions favor water splitting. Overall, these results clarify the dual role of ionic liquids as both CO₂ activators and sacrificial agents, and highlight design principles for improving product selectivity and efficiency in aqueous CO₂ photoreduction systems. Full article

Flow capacitive deionization (FCDI) technology holds significant promise for cost-effective and energy-efficient desalination; however, its practical application is hindered by limited electrode stability and desalination performance. In this study, we propose a novel composite strategy that combines chemical surface modification with surfactant-assisted dispersion to enhance electrode performance in FCDI systems. We observed that the dispersion stability and capacitance of the flow electrodes were significantly improved after oxidation (AC-O) or amination (AC-N) of activated carbon (AC). To further investigate the underlying ion adsorption mechanisms, we performed Density Functional Theory (DFT) simulations. The simulations revealed that oxidative modification (AC-O) enhances chloride ion adsorption through stronger electrostatic and van der Waals interactions, while amination (AC-N) is more effective for sodium ion adsorption. Subsequently, surfactants (sodium dodecyl sulfate, SDS; cetyltrimethylammonium bromide, CTAB) were used to prepare stable and high-performance flow electrodes. Electrochemical characterization and desalination tests in a 1000 mg·L⁻¹ saline solution demonstrated that the AC-O/SDS composite exhibited excellent dispersion stability (>7 d) and significantly enhanced conductivity and specific capacitance, increasing by factors of 2.48 and 2.50, respectively, compared to unmodified AC. This optimized electrode achieved a desalination efficiency of 74.37% and a desalination rate of 6.2542 mg·L⁻¹·min⁻¹, outperforming the unmodified electrode by a factor of 5.72. Our findings provide a robust, sustainable approach for fabricating advanced flow electrodes and offer valuable insights into electrode structure optimization, opening new possibilities for the application of FCDI technology in water treatment and material sciences. Full article

Silicon (Si) may benefit the growth and physiology of various cultivated species, especially under stress conditions. Here, we hypothesized that soil Si supplying as Ca₂SiO₄ would increase the drought tolerance and water use efficiency of young Coffea arabica L. (Arabica coffee) plants, by maintaining shoot water status and photosynthesis under low water availability. To test such a hypothesis, morphological and physiological (leaf water potential, leaf gas exchange, photochemical activity, chlorophyll content) traits of coffee plants were evaluated under varying soil Ca₂SiO₄ applications (0, 3000, 6000 kg ha⁻¹) and water availability. The chemical composition of plant tissues was evaluated under well-watered conditions after six months of Ca₂SiO₄ application, with fertilized plants showing higher concentrations of Ca (leaves and roots) and B (all plant organs) as compared to plants not supplied with Ca₂SiO₄ (control treatment). As there were no changes in Si concentration in plant organs under Ca₂SiO₄ application, our data indicate that the coffee species is a Si non-accumulator, or at least the cultivar ‘Catuaí Vermelho’ evaluated herein. Additionally, the photosynthetic capacity of coffee plants increased with 6000 kg Ca₂SiO₄ ha⁻¹ compared to the control under well-watered conditions, as given by increases in gross and net photosynthesis under light saturation, light saturation point, maximum RuBisCO carboxylation rate, maximum electron transport-dependent RuBP regeneration, and maximum rate of triose phosphate use. Such photosynthetic improvements underlined high leaf CO₂ assimilation, transpiration, carboxylation efficiency, and chlorophyll content in plants grown under Si supplying and well-watered conditions. The negative impact of water deficit on leaf gas exchange was alleviated by Ca₂SiO₄ application, but the instantaneous water use efficiency was maintained as similar in both water regimes, as expected for Si non-accumulator species. Morphologically, coffee stem diameter was increased under Ca₂SiO₄ application, regardless of water regime. In conclusion, our data revealed that high Ca₂SiO₄ doses benefit coffee performance and also suggest that the use of steel slag—an industrial byproduct rich in Ca₂SiO₄—can be considered as a sustainable practice for residue recycling in agriculture while improving C. arabica growth and physiology under varying water availability. Full article

Coal gasification slag (CGS), an industrial solid waste produced during high-temperature (1200–1600 °C) coal gasification, was utilized as the primary raw material, combined with minor additions of coal gangue and calcium oxide, to synthesize ceramsite filter via high-temperature sintering (900–1160 °C) for phosphorus-containing wastewater treatment. The resulting ceramsite was evaluated for compressive strength, apparent porosity, water absorption, mineral phase composition, hydrolysis properties, and phosphorus removal performance. Experimental results revealed that increasing sintering temperature and calcium oxide content shifted the dominant crystalline phases from anorthite and hematite to gehlenite, anorthite, wollastonite, and esseneite, promoting the formation of porous structures. This transition increased apparent porosity while reducing compressive strength. Under optimal conditions (1130 °C, 20 wt.% CaO, 1 h sintering), the ceramsite (CM-20-1130) exhibited an apparent porosity of 43.12%, compressive strength of 3.88 MPa, apparent density of 1.084 g/cm³, and water absorption of 33.20%. The high porosity and abundant gehlenite and wollastonite phases endowed CM-20-1130 with enhanced hydrolysis capacity. Static phosphorus removal experiments demonstrated a maximum phosphorus removal capacity of 2.77 mg/g, driven by the release of calcium and hydroxide ions from gehlenite and wollastonite, which form calcium-phosphate precipitates on the ceramsite surface, enabling efficient phosphorus removal from simulated wastewater. Full article

A large, low-grade Fe–Ti–V oxide deposit occurs within the Xiaohaizi Ultramafic–Mafic intrusion. Based on petrographic observations and electron probe microanalysis (EPMA) of amphibole, this study examines the magmatic evolution and ore-forming processes of the intrusion through analyses of amphibole occurrence, mineral chemistry, and crystallization conditions. Five textural types of amphibole were identified: (i) inclusions, (ii) co-crystallization with early silicates, (iii) reaction rims, (iv) co-crystallization with late Fe–Ti oxides, and (v) phenocrysts. The amphiboles are calcic varieties, mainly composed of magnesio-hastingsite, kaersutite, and tschermakite. Crystallization occurred at temperatures of 901–1013 °C and pressures of 254–424 MPa, with ΔNNO values ranging from −1.3 to +2.8 and estimated melt H₂O contents of 3.3–7.1 wt.%, corresponding to crystallization depths of 9.6–16.0 km. Importantly, the crystallization interval of the Fe–Ti oxides is defined by these amphibole-assemblage conditions, as evidenced by their direct intergrowth. Integration of mineralogical and geochemical data indicates that the Xiaohaizi intrusion underwent five distinct stages of magmatic evolution. During these stages, the crystallization of Fe–Ti oxides was accompanied by notable fluctuations in oxygen fugacity and melt water content. These results suggest that fractional crystallization played a dominant role in ore formation, with possible late-stage liquid immiscibility observed at the mineral scale. Overall, this study proposes that the Xiaohaizi Fe–Ti–V oxide deposit represents a magmatic conduit-type ore-forming system developed within a crystal mush. The enrichment of Fe–Ti oxides is strongly associated with hydrous melts and elevated oxygen fugacity conditions. Full article

Polysaccharide intervention is an effective strategy to regulate properties of emulsions. In this study, xanthan gum (XG), konjac glucomannan (KGM), guar gum (GG), and inulin (IN) were selected to regulate physical and gastrointestinal digestive properties of sodium caseinate (CAS) oil-in-water (O/W) emulsions. The results indicate that IN could not improve CAS emulsion properties, while XG, KGM, and GG significantly reduced droplet size and improved emulsions’ stability. With the increase of the polysaccharide concentration, the G′ and G″ of the emulsions increased and the emulsions showed an obvious “solid-like” state, which effectively slowed down the “strain-thinning” phenomenon. The microstructure demonstrated that the polysaccharide chains are effectively connected with the surface membrane of droplets, which effectively improves interfacial membrane strength and inhibits droplet aggregation. In vitro digestion simulations proved that polysaccharides effectively modulate emulsion lipid release, providing an excellent lipid environment for curcumin absorption in the gastrointestinal tract. The order of the four polysaccharides in improving CAS emulsions was XG > KGM > GG > IN. This study dissects the differential regulation of physical and gastrointestinal digestive properties of emulsion by polysaccharides, providing theoretical support for functional emulsions for diverse requirements. Full article

This study presents a comprehensive thermodynamic simulation and parametric analysis of a single-effect lithium bromide–water (LiBr–H₂O) vapour absorption refrigeration system (VARS) to assess the influence of key operating parameters on its performance, which is primarily measured by the coefficient of performance. The thermodynamic properties of the LiBr–H₂O solution are assessed using P-T-x diagrams to establish the operational limits of the cycle for given constraints, such as the absorber and the generator temperatures and the cycle’s operating pressures. The analysis includes the effects of generator temperature ($T_{gen}$), evaporator pressure ($P_{evap}$), and solution heat effectiveness ($\eta$) on the cycle performance. Additionally, exergy analyses of the cycle’s major components are performed. Simulation results demonstrate that $T_{gen}$ is the most dominant parameter that increases the COP non-linearly from 0.35 at 85 °C to 0.73 at 110 °C (for $\eta$ = 0.5, $T_{cond}$ = 40 °C), while the circulation ratio decreases sharply. Moreover, higher evaporator pressure positively influences the COP; for instance, increasing the evaporator pressure from 0.8 kPa to 1.2 kPa raised the COP from 0.71 to 0.76. This is directly correlated with the increased concentration difference between the strong and weak solutions. The heat recovery effectiveness proved vital for energy optimisation: increasing the recovery effectiveness from 0.5 to 0.9 improved the COP from approximately 0.72 to 0.82 at a fixed $T_{gen}$ of 100 °C. Absorber temperatures limit the minimum operating temperatures of the generator for the vapour production of the refrigerant (water). Moreover, the higher condenser/absorber temperatures significantly deteriorate the performance of the cycle; for instance, raising the operating temperature of the condenser/absorber from 40 °C to 45 °C results in the COP value dropping by up to 35% at a generator operating temperature of nearly 100 °C. Among all cycle components, the generator exhibits the highest exergy loss, especially at lower generator temperatures. These findings provide essential optimisation strategies for designing and operating solar or waste heat-driven LiBr–H₂O VARS units efficiently. Full article

Mn⁴⁺-doped fluoride red phosphors are widely used in white LED lighting and display applications due to their excellent luminescent properties. However, their synthesis relies heavily on highly toxic aqueous hydrofluoric acid, which not only causes severe environmental and soil/water pollution but also makes it difficult to control the microstructure of the products due to the rapid reaction rate. In this study, low-melting-point NH₄HF₂ was used as the molten salt, with KMnO₄ and MnF₂ as manganese sources, to synthesize the red phosphor K₃AlF₆: Mn⁴⁺ via the molten salt method. After the reaction, impurities such as NH₄HF₂ were removed by washing with a dilute H₂O₂ solution. The microstructure, photoluminescence properties, thermal quenching behavior, and application in warm white light-emitting diodes (W-LEDs) of the K₃AlF₆: Mn⁴⁺ phosphors were investigated. The results indicate that the phosphors prepared by this method consist of a single pure phase. By adjusting the molten salt content, the morphology of the product can be transformed from nanoparticle-like to nanorod-like structures. All products exhibit the characteristic red emission of Mn⁴⁺ under blue and violet light excitation, with the optimally doped sample achieving an internal quantum efficiency (IQE) of 69% under blue light excitation. The combination of the obtained K₃AlF₆: Mn⁴⁺ with the yellow phosphor YAG enabled the fabrication of W-LEDs. These W-LEDs achieved a color rendering index (Ra) of 86.8, a luminous efficacy (LE) of 77 lm/W, and a correlated color temperature (CCT) of 3690 K, along with excellent color stability under operating conditions. Full article

Frequent extreme weather events exacerbate agricultural abiotic stress, with drought causing widespread yield loss. Tomato, a globally important vegetable sensitive to water deficit, has been predominantly studied under single-drought scenarios that poorly reflect recurrent field conditions. This study investigated physiological and molecular responses of two tomato genotypes to repeated drought stress. Results showed that the drought-sensitive genotype ‘TGTB’ exhibited faster ABA accumulation and more pronounced ABA-mediated stomatal closure. During the second drought cycle, stomatal pore length and width were significantly smaller than during the first drought, indicating a strong stress memory effect. In contrast, the drought-tolerant ‘LA1598’ showed minimal memory responses. Under extreme drought stress, primed and non-primed ‘TGTB’ plants showed significantly lower H₂O₂ content than controls, whereas primed ‘LA1598’ plants maintained a significantly lower O₂^·− production rate than non-primed plants during both extreme drought cycles. Antioxidant enzyme systems contributed to ROS homeostasis, supported by the regulation of key drought-responsive genes. This study demonstrates genotype-dependent memory capacity and reveals that drought priming enhances repeated drought tolerance through ABA-regulated stomatal adjustment. These findings provide a theoretical basis for improving tomato resilience to recurrent drought and supporting breeding of drought-tolerant varieties. Full article

Mercury (Hg²⁺) contamination in water systems poses a severe environmental and health hazard due to its high toxicity and bioaccumulation potential. In this study, a novel adsorbent was developed by sequentially modifying kaolin via acid–base treatment, titanium dioxide (TiO₂) incorporation, and 3-aminopropyltriethoxysilane (APTES) grafting. Batch adsorption experiments revealed that the fully modified kaolin (TiO₂-loaded and APTES grafted) exhibited the highest adsorption capacity (25.6 mg/g) compared to the acid–base-treated (5.8 mg/g) and TiO₂-loaded (17.7 mg/g) kaolin. Under optimal conditions (75 mg adsorbent dosage; 70 mg/L Hg²⁺; pH 5), the fully modified kaolin maintained its performance even in the presence of varying ionic strengths, natural organic matter, and competing metal ions. Adsorption kinetics followed a pseudo-second-order model, and the equilibrium data were well fitted by the Langmuir isotherm. Antibacterial activity assay revealed that the TiO₂-loaded kaolin effectively inhibited S. aureus (minimum inhibitory concentration = 2.5 mg/mL) and showed moderate activity against E. coli (BL21) (minimum inhibitory concentration = 5 mg/mL). However, antibacterial activity decreased after amine functionalization, indicating a compromise between enhancing adsorption capacity and preserving antibacterial functionality. This study presents a promising cost-efficient approach for the simultaneous removal of Hg²⁺ ions from water matrices and inhibiting bacterial growth, aligning with SDG 6 (Clean Water and Sanitation). Full article

Hydroquinone is a phenolic compound widely used in industry and cosmetics, yet its toxicity has raised global environmental and health concerns. It has been listed by both the US EPA and the European Union as a priority contaminant for monitoring in aquatic systems. In this proof-of-concept (PoC) study, silver nanowires (Ag-NWs) were synthesized via a modified one-pot polyol methodology and characterized by various techniques, including TEM, EDX, SEM, XRD, and UV–vis spectroscopy. The Ag-NWs exhibited peroxidase-like activity, catalyzing the oxidation of TMB/H₂O₂ to yield a blue product. This activity was effectively suppressed by hydroquinone, forming the basis of a simple colorimetric sensing approach. The PoC method showed linearity over 0.08–0.8 µg/mL with a LOD of 26 ng/mL. Furthermore, it was preliminarily applied to tap water, river water, and medicated cream samples, demonstrating acceptable recovery in preliminary applications. As a PoC, the study establishes the feasibility of the Ag-NWs–TMB–H₂O₂ system for hydroquinone detection, while recognizing that comprehensive reproducibility assessment and temporal stability evaluation are required in future work. Full article

There is an urgent need to evaluate the toxicity of xenobiotics and environmental mixtures for preventing loss in water qualityfor the sustainability ofof aquatic ecosystems. A simple prebiotic chemical pathway based on malate formation from pyruvate (pyr) and glyoxalate (glyox) pathway is proposed as a quick and cheap screening tool for toxicity assessment. The assay is based on the pyr and glyox (aldol) condensation reactions, leading to biologically relevant precursors such as oxaloacetate and malate. Incubation of pyr and glyox at 40–70 °C in the presence of reduced iron Fe(II) led to malate formation following the first 3 h of incubation. The addition of various xenobiotics/contaminants (silver, copper, zinc, cerium IV, samarium III, dibytlphthalate, 1,3-diphenylguanidine, carbon-walled nanotube, nanoFe₂O₃ and polystyrene nanoparticles) led to inhibitions in malate synthesis at various degrees. Based on the concentration inhibiting malate concentrations by 20% (IC20), the following potencies were observed: silver < copper ~ 1.3-diphenylguanidine ~ carbon-walled nanotube < zinc ~ samarium < dibutylphthalate ~ samarium < Ce(IV) < nFeO₃ < polystyrene nanoplastics. The IC20 values were also significantly correlated with the reported trout acute lethality data, suggesting its potential as an alternative toxicity test. The pyr-glyox pathway was also tested on surface water extracts (C18), identifying the most contaminated sites from large cities and municipal wastewater effluents dispersion plume. The inhibition potencies of the selected test compounds revealed that not only pro-oxidants but also chemicals hindering enolate formation, nucleophilic attack of carbonyls and dehydration involved in aldol-condensation reactions were associated with toxicity. The pyr-glyox pathway is based on prebiotic chemical reactions during the emergence of life and represents a unique tool for identifying toxic compounds individually and in complex mixtures. Full article