Search Results (1,656)

The existence of residual ammonium in weathered crust elution-deposited rare earth ore (WREO) tailings will cause serious environmental pollution, and it is necessary to remove it from the ore body. In this work, ferric chloride was applied as the eluent, and the effects of the ferric salt concentration, liquid/solid ratio, and the eluting temperature on the ammonium removal process were investigated. The results indicated that ferric chloride demonstrated a significant capability to eliminate residual ammonium (RA) from rare earth (RE) tailings. The optimal conditions identified for this process included a ferric salt concentration of 0.06 mol/L, a liquid/solid ratio of 2:1, and a temperature of 25 °C. Under optimal conditions, the removal efficiency of RA by ferric chloride was measured at 97.47%. The NH₄⁺ concentration in the final stage leachate was determined to be 1.85 mg/L, which satisfies the environmental standards. Kinetic analysis revealed an internal diffusion-controlled elution mechanism for RA in the RE ore tailings, with a reaction order of 0.28 and an activation energy of 13.36 kJ/mol. FT-IR characterization results showed that most of the RA salts were effectively removed. This study establishes a feasible approach to remove RA from RE ore tailings, thereby laying a theoretical foundation for this process. Full article

(1) Background: The conservation of plant resources is important because many wild plant populations are threatened by various influences. Growing plants from seeds is one way to ensure their survival. Comparing the biological potential of extracts between plants cultivated from seeds and wild plants provides information about their specialized metabolites. For this reason, this study compared the biological potential of phenolic extracts from four wild-collected species of the genus Veronica and the same four cultivated species. The studied species of the genus Veronica are V. anagallis-aquatica L., V. persica Poir., V. polita Fr. and V. hederifolia L. (2) Methods: The phenolic composition was investigated with LC-QTOF (Liquid Chromatography-Quadrupole Time-of-Flight). The main methods for biological activities were as follows: ORAC (Oxygen Radical Absorbance Capacity) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical for antioxidant activity, the disk diffusion test for antibacterial activity and the MTS test of cytotoxic activity. (3) Results: The major compound in all extracts was apigenin. Cultivated species showed higher antioxidative activity. Phenolic compounds isolated from the V. anagallis-aquatica species showed the highest cytotoxic effect on all tested lines. The extracts showed antibacterial activity on three bacterial strains: Streptococcus pyogenes, Listeria monocytogenes and L. innocua. Extracts of V. anagallis-aquatica showed the highest antibacterial activity, both from the natural habitat and cultivated habitat. (4) Conclusions: A comparison of the different activities tested for phenolic extracts between wild and cultivated species of the genus Veronica showed that cultivated species also have significant biological activity and are suitable for further research and applications. Full article

This article discusses the potential of using the double-Wiebe function to model combustion in a compression-ignition engine fueled by diesel fuel or its substitutes, such as hydrotreated vegetable oil (HVO) and rapeseed methyl ester (RME), and hydrogen injected into the engine intake manifold. The hydrogen amount ranged from 0 to 35% of the total energy content of the fuels burned. It was found that co-combustion of liquid fuel with hydrogen is characterized by two distinct combustion phases: premixed and diffusion combustion. The premixed phase, occurring just after ignition, is characterized by a rapid combustion rate, which increases with an increase in hydrogen injected. The novelty in this work is the modified formula for a double-Wiebe function and the proposed parameters of this function depending on the amount of hydrogen added for co-combustion with liquid fuel. To model this combustion process, the modified double-Wiebe function was proposed, which can model two phases with different combustion rates. For this purpose, a normalized HRR was calculated, and based on this curve, coefficients for the double-Wiebe function were proposed. Satisfactory consistency with the experiment was achieved at a level determined by the coefficient of determination (R-squared) of above 0.98. It was concluded that the presented double-Wiebe function can be used to model combustion in 0-D and 1-D models for fuels: RME and HVO with hydrogen addition. Full article

Mushrooms have long been recognized as a rich source of bioactive compounds, including phenolics, that possess important antioxidant, antimicrobial, and antibacterial properties, including activity against drug-resistant bacteria. This study evaluated total phenolic profile and content, total flavonoids content, the antioxidant activities, antimicrobial and antibacterial activities, of water extracts of edible mushrooms from Romanian deciduous forests, including Cantharellus cibarius, Russula virescens, Lactarius piperatus, and Boletus edulis. The extracts were characterized using high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) and Fourier Transform Infrared Spectroscopy (FTIR) analysis. Antioxidant activity was determined using DPPH radical-scavenging activity and ABTS radical cation decolorization assay. Antimicrobial and antibacterial activities were tested using standard strains of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, and Streptococcus pneumoniae following diffusion testing and time-killing assay, respectively. The HPLC-MS results indicated that major compounds in all the mushrooms belonged to the subclass of hydroxybenzoic acids. Trans-cinnamic acid and hydroxybenzoic acids, particularly gallic acid, 2,3-dihydroxybenzoic acid, and gentisic acid, were the predominant compounds detected in BEE and CCE. Their concentrations were measured as follows: 24 μg/mL, 63 μg/mL, 56 μg/mL, and 14 μg/mL, respectively, for BEE, and 26 μg/mL, 42 μg/mL, 7 μg/mL, and 5 μg/mL, respectively, for CCE. Among phenolic compounds, 2-dihydroxybenzoic acid, 2,3-dihydroxybenzoic acid, p-anisaldehyde, and gentisic acid were positively correlated with both DPPH (45% and 21% inhibition rate for BEE and CCE, respectively) and ABTS (64 and 31% inhibition rate for BEE and CCE, respectively) antioxidant activities. The FTIR analysis revealed the presence of lipids, proteins, and polysaccharides, extracted in different ratios in the water extract. All mushroom extracts showed a dose-dependent response with higher antimicrobial and antibacterial activities at the highest concentration (26.3 µg phenolics BEE, 12.7 µg pphenolics CCE, 28.3 µg phenolics LPE, and 14.5 µg phenolics RVE per well for antimicrobial activity and 175.2 µg phenolics/mL BEE, 84.4 µg phenolics/mL CCE, and 188.9 µg phenolics/mL LPE for antibacterial activity). These species demonstrate potential for the development of alternative antimicrobial formulations, particularly relevant in the context of antibiotic resistance. Full article

The deep-sea mining pump is a core component in deep-sea mineral resource extraction, whose performance directly determines the transportation efficiency of coarse-grained ore and overall system reliability. However, deep-sea mining pumps suffer from severe abrasion of internal components due to continuous impact by coarse ore particles, leading to short service life and high maintenance costs. These issues adversely impact the economics and continuity of mining operations. Consequently, studying the solid-liquid flow to understand wear mechanisms and develop optimized, wear-resistant designs is crucial for enhancing pump performance. This paper establishes a fully coupled solid-liquid two-phase flow platform by integrating Fluent and EDEM, based on an artificial diffusion-based coarse-particle CFD-DEM (Computational Fluid Dynamics-Discrete Element Method) approach, to systematically investigate the critical technical issue of internal pump wear. The study finds that wear in traditional spiral centrifugal pump blades is primarily concentrated on the leading edge and the middle section. On the leading edge, wear comprises 56.4% cutting wear and 44.7% impact wear; in contrast, cutting wear accounts for 96.8% of the total wear in the middle section. To address the premature failure of traditional impeller blades caused by localized wear concentration, this paper proposes an optimized design for a novel spiral centrifugal impeller with segmented blades. By modifying the impeller structure, the proposed design relocates the primary wear zones to the leading edges of the two blade segments, thereby facilitating the application of anti-wear treatments. Full article

The dynamics of dense colloidal systems are not fully understood. In the study of these types of systems, computer simulations based on the so-called hard sphere model play a significant role. In the presented work, we consider a system of hard spheres of the same size but different mobilities (molecules with high mobility correspond to solvent molecules, while molecules with reduced mobility are colloid particles) at varying concentrations. For this purpose, a two-dimensional lattice and an thermal model of such systems was designed. In order to determine the properties of such systems, a Monte Carlo computer simulation was used, employing the Dynamic Lattice Liquid (DLL) algorithm. Our main aim was to determine how the dynamic behavior of the system in the short time affects the long-time behavior. For this purpose, we investigated the cross-ratios of the diffusion coefficients in the short and long time of the considered system elements. It was found that the reduction in the solvent mobility with increasing concentration of colloidal particles in a short time leads to a very similar reduction in the mobility of the colloid particles in a long time, but we do not observe such behavior in the case of the solvent, i.e., there is a decrease in the value of the solvent diffusion coefficient in the long time with the change in the concentration of colloid particles, but it is difficult to connect it in a simple way with the decrease in the diffusion coefficient in the short time. Full article

Lime-based repair mortars, plasters, and renders are widely utilized in the conservation of traditional buildings. Historically, considerable emphasis has been placed on ensuring that new repair mortars are aesthetically compatible with existing historic materials. However, comparatively less focus has been placed on ensuring hygric compatibility, which is critical to maintaining the moisture equilibrium of traditional masonry walls and preventing moisture accumulation caused by repair interventions. The FabTrads project examined the hygrothermal properties of newly fabricated quicklime mortars, prepared with binder-to-aggregate ratios of 1:2 and 1:4, alongside a range of historic lime-based mortars, plasters, and renders, sourced from buildings across Ireland. This paper presents a comparative analysis of their hygric behaviour. Experimental results indicate that the capillary absorption of the fabricated mortars correlates well with their historic counterparts. Both fabricated mortars exhibited vapour diffusion resistance factors within the range of the historic samples, albeit towards the higher end. Hygrothermal simulations of vapour and liquid water transport revealed that the moisture behaviour of the fabricated mortars is largely within the range of performance of their historic counterparts. Relative humidity was slightly elevated for the fabricated mortars in the models concerning vapour transfer. Notwithstanding this, the findings provide a reassuring indication that the hygric performance of fabricated quicklime mortars is comparable with that of traditional lime-based materials, supporting their appropriate use in conservation practices without adversely affecting the moisture dynamics of the building fabric. Full article

As industry moves from fossil fuels to green energy, substituting hydrocarbons with hydrogen as an energy carrier seems promising. Hydrogen can be stored in salt caverns, depleted hydrocarbon fields, and saline aquifers. Among other criteria, these storage solutions must ensure storage safety and prevent leakage. The ability of a caprock to prevent fluid from flowing out of the reservoir is, thus, of utmost importance. In this review, the main factors influencing fluid flow are examined. These are the wettability of the caprock formation, the interfacial tension (IFT) between the rock and the gas or liquid phases, and the ability of gases to diffuse through it. To achieve effective sealing, the caprock formation should possess low porosity, a disconnected or highly complicated pore system, low permeability, and remain strongly water-wet regardless of pressure and temperature conditions. In addition, it must exhibit low rock–liquid IFT, while presenting high rock–gas and liquid–gas IFT. Finally, the effective diffusion coefficient should be the lowest possible. Among all of the currently reviewed formations and minerals, the evaporites, low-organic-content shales, mudstones, muscovite, clays, and anhydrite have been identified as highly effective caprocks, offering excellent sealing capabilities and preventing hydrogen leakages. Full article

Indium, widely used in indium–tin oxide (ITO) coatings for liquid crystal displays (LCDs), is a scarce and strategically important metal with increasing demand. Recycling waste LCD panels offers an efficient secondary source to address supply risks and environmental concerns. In this study, a hydrometallurgical flow sheet was developed under mild conditions for indium (In) recovery. Leaching trials with sulphuric acid at varying concentrations, pulp densities, temperatures, and times showed that 5% H₂SO₄ (v/v) with 100 g/L pulp density at 60 °C for 30 min achieved ~98% dissolution of In, while minimizing the co-leaching of Al and Sn. Kinetic analysis indicated a diffusion-controlled mechanism for In dissolution with an activation energy of 21.2 kJ mol⁻¹. The leached liquor was further purified through solvent extraction by 20% Cyanex 921 (v/v), achieving optimum In extraction at pH 2.5 with an organic-to-aqueous phase ratio of 1/3, reaching equilibrium within 15 min. The McCabe–Thiele plot shown indicates the complete In extraction in two stages. FT-IR studies confirmed the In-extractant bonding at optimized conditions. 10% H₂SO₄ (v/v) was used for the stripping of In from the loaded organic, ensuring nearly complete back-transfer of indium with excellent phase separation. The integrated process yielded ~97% In recovery in stripping. The pure salt of Indium could be obtained by evaporation/crystallization of pure indium solution. The developed process has the potential to be transferred for commercial exploitation after scale-up and pilot trial. Full article

Utilization of waste tires via pyrolysis is a promising solution. The liquid hydrocarbons generated during this process could be used for enhancing low-reactivity coals for energy application. Current study investigates oxidation and combustion characteristics (including composition of gaseous combustion products) of low-reactivity coal mixed with liquid hydrocarbons from pyrolysis of waste tires with a concentration up to 20%wt at 700 °C. The oxidation tests via TG-analyzer revealed that at heating rates up to 10 °C/min, the process had one stage, associated with combined oxidation of coal-liquid hydrocarbons mixture. Starting from 10 °C/min the second stage occurred at temperature ~400 °C due to evaporation of light components of the mixture. Combustion tests at experimental setup at 700 °C revealed almost linear increase in fuel reactivity, expressed into decline in ignition delay time of mixtures (up to 71.6%) with increasing concentration of liquid hydrocarbons, while flame and diffusion combustion times were, in contrast, increasing (by up to 69.5%). Increasing concentration of additives from 2.5 to 20%wt resulted not only in change in the form of obtained mixture but also changed the combustion mechanism from predominantly heterogeneous smoldering to majorly homogeneous gas-phase ignition and combustion. Gas-phase combustion products concentration curves generally complimented previously observed peculiarities of combustion. Increased CO and NO_x concentrations in combustion products of coal mixed with liquid hydrocarbons revealed necessity in additional tailoring of burner characteristics for mitigating these effects. The compromise composition of mixture was found to include 10%wt of liquid hydrocarbons for enabling quick gas-phase ignition while maintaining moderate level of combustion products emissions. Full article

Thai medicinal flowers, namely Mesua ferrea L. (Bunnak), Mammea siamensis T. Anderson (Saraphi), and Clitoria ternatea (Anchan) have long been valued for their traditional medicinal. This study investigated their phytochemical composition and bioactivities, with a particular focus on antioxidant and antibacterial properties. Methods: Ethanolic flower extracts were analyzed by high-performance liquid chromatography (HPLC) and liquid chromatography–mass spectrometry (LC–MS). Antioxidant activities were determined by DPPH, ABTS, and FRAP assays. Antibacterial activity against Escherichia coli, E. coli O157:H7, Salmonella Typhi, Shigella dysenteriae, and Vibrio cholerae were assessed by agar well diffusion, broth dilution methods, and time–kill assays. Biofilm formation, biofilm disruption, and bacterial adhesion to Caco-2 cells were evaluated. Morphological changes in E. coli O157:H7 were examined using scanning electron microscopy (SEM), and leakage of intracellular contents (DNA, RNA, proteins) were quantified. Results: HPLC analysis revealed the highest level of gallic acid in M. ferrea and quercetin in M. siamensis. LC–MS analysis identified fifteen putative metabolites across the flower extracts, including quercetin, kaempferol, catechin, and luteolin derivatives, with species-specific profiles. C. ternatea extract exhibited the greatest total flavonoid content and antioxidant activity. Among the extracts, M. ferrea exhibited the strongest inhibitory effect, with inhibition zone of 13.00–15.00 mm and MIC/MBC values of 31.25–62.5 mg/mL. All extracts exhibited time-dependent bactericidal activity, significantly inhibited biofilm formation, disrupted established biofilms, and reduced bacterial adhesion to intestinal epithelial cells. SEM revealed membrane disruption in E. coli O157:H7 and leakage of intracellular components. Conclusions: Thai medicinal flower extracts, particularly M. ferrea, possess strong antioxidant and antibacterial activities. Their ability to inhibit biofilm formation, interfere with bacterial adhesion, and disrupt bacterial membranes highlights their potential as natural alternatives for preventing or controlling enteric bacterial infections. Full article

To address limitations such as cleaning difficulties or secondary contamination/damage of cultural relics caused by the uncontrollable diffusion of water/cleaning agent/dirty liquids during the cleaning process in traditional cleaning methods, this study, using cotton textiles as an example, systematically investigated the cleaning efficacy of four in situ methods (blank gel, cleaning gel, ultrasonic emulsification, and gel + ultrasonic emulsification synergistic cleaning) on eight types of stains, including sand, clay, rust, blood, ink, oil, and mixed solid/liquid stains. Building upon this, this study proposed an efficient, targeted, in situ, and controllable cleaning strategy tailored for fragile, stained textile relics. Results demonstrated that, regardless of the stain type, the synergistic cleaning method of G+U (gel poultice + ultrasonic emulsification) consistently outperformed the cleaning methods of blank gel poultice, cleaning gel poultice, and ultrasonic emulsification. Furthermore, the gel loaded with cleaning agents was always more effective than the blank gel (unloaded cleaning agents). The poultice methods of blank gel and cleaning gel were better suited for solid stains, while the ultrasonic emulsification cleaning method was more effective for liquid stains. Meanwhile, it was also found that the optimal cleaning method proposed in this study (the G+U synergistic cleaning method) was a cleaning method that restricted the cleaning agent within the gel network/emulsion system, and utilized the porous network physical structure of gel, the chemical action of emulsion’s wetting/dissolving dirt, and the cavitation synergistic effect of ultrasound to achieve the targeted removal of contaminants from relics’ surfaces. Crucially, the cleaning process of G+U also had the characteristics of controlling the cleaning area at the designated position and effectively regulating the diffusion rate of the cleaning solution within the treatment zone, as well as the reaction intensity. Therefore, the proposed optimal (the synergistic cleaning method of G+U) cleaning method conforms to the significant implementation of the “minimal intervention and maximal preservation” principle in modern cultural heritage conservation. Consequently, the synergistic cleaning method of G+U holds promise for practical application in artifact cleaning work. Full article

Vanadium is a strategic metal with critical applications in steel alloys, aerospace, chemical catalysis, and energy storage. However, conventional extraction methods such as high-temperature salt roasting are energy-intensive and environmentally challenging. This study investigated the extraction of V, Ti, and Fe from titanomagnetite ore using aqueous solutions of two ionic liquids (IL), 1-butyl-3-imidazolium hydrogen sulphate ([Bmim][HSO₄], and 1-butyl-3-methylimidazolium hexafluorophosphate [Bmim][PF₆]) as well as two deep eutectic solvents (DESs) (choline chloride:oxalic acid and choline chloride:succinic acid). Na₂CO₃ and Na₂SO₄ roasting were used as benchmarks for comparison purposes. Leaching was performed across a range of concentrations and temperatures, and metal recoveries were quantified by atomic absorption spectroscopy (AAS). Among all methods, ChCl:OA DES achieved the best leaching efficiencies of 97.6% for V, 76.1% for Ti, and 68.8% for Fe at 50% (v/v) and 100 °C, outperforming [Bmim][HSO₄] and conventional roasting. Kinetic analysis using the shrinking core model indicated that leaching is predominantly diffusion-controlled, with apparent activation energies of 35.1 kJ/mol for V, 28.3 kJ/mol for Ti, and 29.8 kJ/mol for Fe. The results demonstrate that ChCl:OA DES provides a low-temperature, biodegradable, and cost-effective approach for V, Ti and Fe extraction, offering a sustainable alternative to conventional salt roasting methods. Full article

The thermal and optical properties of aqueous dispersions of magnetite nanoparticles were studied by dual-beam thermal-lens spectrometry. Surface-modified magnetite nanoparticles with an average crystal size of 7.5 nm were synthesized by a simple, one-stage method of coprecipitation followed by surface functionalization. For this purpose, the most popular and promising modifiers based on surfactants, polyelectrolytes, biopolymers and organic acids were used. The effect of the concentration of nanoparticles (in the range from 0.01 to 5 mg/L) and the nature of the surface modifier on the thermal diffusivity of the dispersion was studied. It was found that at concentrations of 0.4–0.6 mg/L, the dispersions exhibit heat-accumulating properties, which may be promising in the development of a magnetically controlled heat-conducting liquid. Thermal lens spectrometry in the steady-state measurement mode was used to reveal the processes of deposition and adsorption of magnetite nanoparticles on the surface of a quartz cell, leading to an apparent increase in thermal diffusivity by more than 30%. The paper touches upon the issues of accuracy and precision of temperature diffusion measurements, processing, and presentation of measurement results of time-resolved transient and steady-state signals for dispersed systems. The ratio of the change in the steady-state thermal-lens signals to the change in concentration regarding the concentration (dϑ/dc vs. c) provides a way to identify a systematic error at a low level (less than 5%) of thermal-lens measurements caused by a high concentration (or optical absorption) of the object. Various options for signal normalization (in terms of power, absorbance, and pure-solvent signal) are considered, and their advantages and disadvantages are discussed. An approach to using thermal diffusivity as a function of the steady-state signal of the sample is proposed. This approach allows for a comparative thermal-lens analysis of objects with different optical and thermal properties. Full article

This paper investigated the tunnel slags generated from a specific tunnel project to systematically assess their environmental risk through phase composition, chemical composition, acidification potential, and heavy metal speciation. Leaching experiments were conducted under various influencing factors, including particle size, time, liquid-to-solid ratio, pH, temperature. The release concentration of heavy metals from the tunnel slag particles follows the following order: Zn > Cu > Cr. This is primarily attributed to the preferential release of Zn under acidic conditions due to its high acid-soluble state, while Cr, which is predominantly present in the residual state, exhibits very low mobility. Furthermore, decreased particle sizes, increased liquid-to-solid ratios, elevated leaching temperatures, extended leaching times, and lower pH values can effectively promote the dissolution of heavy metals from the tunnel slag. The cumulative leaching curves of Cr, Cu, and Zn from the three types of tunnel slags conform to the Elovich equation (R² > 0.88), indicating that the release process of heavy metals is primarily controlled by diffusion mechanisms. The S- and Fe/Mg-rich characteristics of D3 confers a high acidification risk, accompanied by a rapid and persistent heavy metal release rate. In contrast, D2, which is influenced by the neutralizing effect of carbonate dissolution, releases heavy metals at a steady rate, while D1, which is dominated by inert minerals like quartz and muscovite, exhibits the slowest release rate. It is recommended that waste management engineering prioritize controlling S- and Fe/Mg-rich tunnel slags (D3) and mitigating risks of elements like Zn and Cu under acidic conditions. This study provides a scientific basis and technical support for the environmentally safe disposal and resource utilization of tunnel slag. Full article