Search Results (656)

Emulsified collectors (ECs) have attracted increasing attention in coal slime flotation because of their superior dispersion characteristics and collecting performance compared with conventional hydrocarbon collectors. However, the relationship between flotation performance and the effects of ECs on microorganisms in circulating water remains poorly understood. In this study, four ECs were prepared using cationic (dodecyltrimethylammonium bromide (DTAB)), anionic (sodium dodecyl sulfate (SDS)), nonionic (Tween-80), and solid particle-based (β-cyclodextrin (CD)) emulsifiers. The droplet size distribution, flotation performance, adsorption behavior, and microbial response were systematically evaluated. The results showed that ECs significantly improved coal slime flotation compared with conventional kerosene. Among the surfactant-based ECs, smaller oil droplet sizes resulted in higher clean coal recovery, demonstrating the critical role of collector dispersion in flotation performance. Fourier transform infrared spectroscopy provided qualitative evidence of stronger relative adsorption of ECs on coal surfaces than that of conventional kerosene. Yeast survival tests revealed that all ECs exhibited less adverse impact on microorganisms than kerosene. However, for surfactant-based ECs, microbial survival decreased as flotation performance increased. A preliminary negative correlation (R² = 0.9323, n = 4, where “n” denotes the number of collector formulations tested) was observed between the yeast survival rate and the number of oil droplets, suggesting that fine oil droplets remaining in the aqueous phase may have contributed to reduced microbial viability. In contrast, the β-CD-stabilized Pickering emulsion achieved both the highest flotation efficiency index (56.22) and the highest yeast survival rate (66.49%), outperforming Tween-80-EC (54.90 and 58.65%), SDS-EC (50.95 and 61.45%), DTAB-EC (50.08 and 63.31%), and conventional kerosene (40.32 and 53.35%). These findings demonstrate the importance of balancing flotation performance and environmental compatibility in the design of sustainable flotation collectors for coal processing. Full article

This study experimentally compares the thermal performance of two vertically oriented passive solar water heating systems under arid outdoor conditions in Gabes, Tunisia: a thermosiphon solar water heater (TSWH) and an integrated solar water heater (ISWH). Both prototypes were installed side by side, facing south, with identical collector areas and the same climatic exposure. Experiments were conducted over two consecutive clear-sky days under no-load and load conditions. The systems were evaluated in terms of water-temperature evolution, thermal stratification, thermal efficiency, heat-retention behaviour, overall heat-loss coefficient, and useful hot-water production. The results showed that the ISWH achieved higher peak water temperatures, reaching 59.8 °C and 57.5 °C during the two test days, compared with 48.55 °C and 53.65 °C for the TSWH. The ISWH also showed higher peak thermal efficiencies of approximately 49% and 48%, while the TSWH reached approximately 41% and 40%. Under hot-water extraction conditions, the ISWH delivered about 25 L of usable hot water at 45 °C, compared with 19 L for the TSWH. However, the TSWH exhibited better thermal retention, with a lower overall heat-loss coefficient of 1.763 W/m²K compared with 2.38 W/m²K for the ISWH. These findings demonstrate a clear trade-off between rapid daytime heat capture and non-solar heat preservation. The ISWH is more suitable for applications requiring higher daytime hot-water production, whereas the TSWH is preferable when improved heat retention after solar input decreases is required. Full article

Rare earth elements (REEs) flotation from carbonatitic ores remains challenging due to the complex association between REE-bearing minerals and carbonate-rich gangue phases. Although previous studies have reported REE beneficiation from the Fen Deposit, the influence of depressant type, sodium silicate dosage, EDTA addition, and collector selection on flotation selectivity remains poorly understood. Therefore, this study presents a preliminary assessment of different reagent schemes for the flotation of REE-bearing minerals from the Fen Deposit. Chemical and mineralogical characterization confirmed the predominance of light REEs, mainly Ce and La, associated with monazite and fluorocarbonate minerals of the bastnäsite–parisite–synchysite group. Flotation screening tests revealed limited gangue rejection, particularly for Ca- and Ba-bearing minerals, indicating that mineralogical complexity strongly influences flotation selectivity. Among the depressants evaluated, sodium silicate and citric acid exhibited the most promising performance, while EDTA enhanced the total rare earth oxides (TREO) grade at higher sodium silicate dosages. Collector tests resulted in moderate REE enrichment in the overflow products, with NaOL yielding the highest recovery (~62%). However, TREO grades remained relatively low (~2.3–2.7%), suggesting that reagent selection alone is insufficient to overcome the flotation limitations imposed by the ore from the Fen Deposit. The results provide an exploratory evaluation of reagent schemes for Fen carbonatite ore and identify key challenges and opportunities for future process optimization. Full article

The high-voltage spinel ${\mathrm{LiNi}}_{0.5}{\mathrm{Mn}}_{1.5}{\mathrm{O}}_4$ (LNMO) is a promising cobalt-free cathode material for lithium-ion batteries, yet its integration as a binder-free thin film on metallic current collectors via simple solution routes remains underexplored. Here, LNMO films were synthesized on 304 stainless steel (SS304) by metal–organic decomposition (MOD) from metal–acetate precursors in ethanol, followed by spin-coating and annealing at 500, 600, and 700 °C under flowing ${\mathrm{O}}_2$. The films were characterized by XRD, FESEM–FIB cross-sectioning, EDS, and XPS, and tested as binder-free cathodes by cyclic voltammetry and galvanostatic charge/discharge. All samples are dense, approximately 1.9 μm thick, and crystallize in the disordered spinel phase. The LNMO crystallite size increases from 21.9 to 43.8 nm between 500 and 700 °C, while the grain size also shows a temperature dependence, increasing the average size from 25 up to 56 nm in diameter. XPS confirms ${\mathrm{Mn}}^{4+}$ as the dominant manganese surface species (45–49%) across all samples. The films deliver reversible discharge capacities of 92, 92, and 70 mAh ${\mathrm{g}}^{-1}$ at 0.1 C for LNMO500, LNMO600, and LNMO700, respectively, with well-defined ${\mathrm{Ni}}^{2+}{\mathrm{/Ni}}^{3+}$ and ${\mathrm{Ni}}^{3+}{\mathrm{/Ni}}^{4+}$ redox peaks at 4.7 and 4.8 V. DFT calculations independently predict a voltage plateau at ∼4.7 V for $0.2\le x\le 1$, in agreement with the experimental profiles. These findings establish MOD as a viable, vacuum-free route to the synthesis of nanostructured LNMO cathodes. Full article

Selective separation of quartz and feldspar is vital for high-purity silicate raw materials but is challenging due to similar surface chemistries. Conventional flotation typically requires high reagent dosages and hazardous chemicals, raising environmental and economic issues. This study proposes a sustainable flotation strategy using green, bio-derived reagents to improve quartz–feldspar separation by eco-friendly bio-derived reagents. Sodium oleate, a fatty acid collector, was used with low-toxicity modifiers to create synergistic systems. Flotation performance was tested by reagent dosage and pH, with mineral characteristics analyzed via X-ray Fluorescence (XRF) and Particle Size Distribution (PSD). Results showed that the investigated reagent systems improved the differential flotation response between quartz and K-feldspar. Under the optimized flotation conditions (pH 9.24), quartz recovery reached 84.01%, demonstrating that environmentally friendly reagent combinations can achieve favorable flotation performance while reducing chemical consumption. Response Surface Methodology (RSM) was used to optimize flotation variables like pH and reagent dosage, developing a model to predict conditions for favorable flotation response, enabling systematic process improvement. These findings highlight reagent-system optimization as an eco-friendly method for mineral beneficiation, aligning with green chemistry and sustainable practices. Full article

Greenhouse cultivation in winter faces significant challenges in maintaining suitable air temperature and humidity conditions for crop growth during nighttime. This study proposes an innovative thermal management system that integrates a solar air collector circulation system with clay bricks to regulate the microclimate of plastic greenhouses. Comparative experiments were conducted in Suzhou, China (subtropical monsoon climate), using two identical greenhouses (2.6 m × 1.5 m × 2.0 m) over nine consecutive days in winter. Three experimental scenarios were designed and implemented, and the results demonstrated that the clay brick system improved the greenhouse temperature and humidity regulation performance. Under the relatively optimal schedule (9:00–16:00 external circulation, 16:00–9:00 internal circulation), the average nighttime indoor air temperature was 13.68 °C during the three experimental days. The cumulative suitable temperature duration (10–35 °C) reached 4050 min over the three test days, which was 30.6% higher than that of the ordinary greenhouse, and the suitable relative humidity duration (40–80%) was 1140 min, an increase of 40.7% during the three experimental days. This study innovatively combines low-cost clay bricks with solar air collectors for passive temperature and humidity control in greenhouses and determines the relatively optimal operation schedule for application in winter. Featuring low cost, simple operation and high sustainability, the system provides a novel energy-saving technical solution for microclimate regulation in agricultural greenhouses in winter. Full article

Accurate design and performance assessment of solar thermal domestic hot water systems coupled with a heat pump auxiliary typically requires transient simulation, as the system’s behavior depends on multiple interactions among collector characteristics, storage stratification, control logic, weather, and draw-off timing. Monthly methods such as the f-chart are useful for first-pass estimates, but they do not resolve stratification, thermostat operation, or demand timing, and they may become inaccurate for stratified thermostat-controlled systems. Direct comparisons of locally inspectable symbolic and black-box surrogate families for this system class remain limited. A 10,982-case development dataset was generated from minute-resolved annual MATLAB simulations, parameterized by collector area, optical efficiency, and first- and second-order loss coefficients. Three surrogate families were benchmarked under a unified protocol, random forest-assisted shape-constrained symbolic regression (SR), feed-forward artificial neural network (ANN) models, and Automatic Learning of Algebraic Models for Optimization (ALAMO), with the f-chart used as a monthly reference method. The targets were the 12 monthly solar fractions under the direct solar heat definition and the corresponding annual mean solar fraction, evaluated on the same independent 991-case test set. SR achieved the lowest average error (mean absolute percentage error, MAPE = 0.82%; root mean square error, RMSE = 0.006), followed by the ANN (MAPE = 2.07%, RMSE = 0.028) and ALAMO (MAPE = 3.67%, RMSE = 0.060), with Nash–Sutcliffe efficiency (NSE) values above 0.98 for all models. Evaluation times were 0.0026–0.124 s per target, compared with about 1000 s for one full-year simulation. These results define the study as a common protocol benchmark within the studied simulator-defined envelope. SR gives the strongest accuracy with local symbolic inspectability, the ANN remains the flexible retrainable option, and ALAMO provides compact algebraic evaluation with the shortest learned model runtime. Full article

Imidazole-based ionic liquids hold immense potential in the field of mineral flotation due to their tunable properties. In this study, three imidazole-based ionic liquids with varying carbon chain lengths (OMB, DMB, and HMB) were selected as collectors for quartz flotation to systematically investigate the microscopic mechanisms by which carbon chain length influences the agglomeration and flotation behavior of quartz. Flotation tests and online particle-bubble monitoring (PBM) results indicate that the elongation of the collector’s carbon chain significantly enhances its collecting ability and reduces the required reagent dosage. To achieve the complete recovery of quartz in a neutral system, a dosage of 35 mg/L is required for OMB, whereas HMB requires only 8 mg/L. As the carbon chain lengthens, the optimal pH range for highly efficient flotation shifts from alkaline to neutral-acidic. Interfacial measurements and mechanistic analyses (Zeta potential and FTIR spectroscopy) confirm that the imidazole ring of the collector physically adsorbs onto the quartz surface through the synergistic action of electrostatic forces and hydrogen bonding, thereby inducing the hydrophobic agglomeration of particles. Notably, in a strongly alkaline system (pH = 11), the long-chain HMB promotes the formation of oversized quartz agglomerates. This leads to a depletion of free reagents in the liquid phase and destabilizes the bubble liquid film, ultimately triggering a sharp decline in recovery. Density functional theory (DFT) calculations further corroborate the structure–activity relationship at the molecular level: the extension of the carbon chain increases the highest occupied molecular orbital (HOMO) energy and electron-donating ability. The adsorption energy of HMB on the quartz (001) surface reached −350.2 kJ/mol, exhibiting the strongest solid–liquid interfacial affinity. This study elucidates the competitive mechanism of carbon chain length in regulating electrostatic adsorption, hydrophobic agglomeration, and froth stability, providing a solid theoretical foundation for the molecular design of novel green flotation reagents for quartz. Full article

The increase in small satellites demands the integration of commercial components to reduce costs and development time. However, the lack of standardized system-level methodologies to mitigate radiation-induced degradation limits their adoption. Although majority-carrier technologies such as MOSFET transistors dominate space power electronics, modern commercial off-the-shelf BJT transistors present a robust and cost-effective alternative. This paper evaluates the viability of the new-generation commercial off-the-shelf BJT transistors in space radiation environments by analyzing their response to total ionizing dose (measured at the circuit level) and single-event effects (inferred from component-level data). A fault-tolerant design methodology is proposed based on the strict definition of the safe operating area: the collector-emitter voltage is limited to safe values to mitigate single-event burnout, and an overdrive margin, specifically a 5× worst-case factor, is applied to compensate for the parametric degradation of the current gain. These strategies are empirically validated through two circuits: a voltage clamp and a proportional base driver operating in the 5 W to 40 W range. Experimental tests on the voltage clamp demonstrate stable operation up to one hundred kilorads, exceeding the 50 krad mission requirement by 100%. This indirectly supports the proportional base driver through shared mitigation principles, which rely on base current over-dimensioning to compensate for TID degradation. In conclusion, by applying appropriate derating rules, commercial off-the-shelf BJT transistors constitute a viable and robust alternative for small satellite power systems, mitigating the need for expensive radiation-hardened components. Full article

Flotation is a fundamental unit operation in mineral processing; however, achieving high selectivity while reducing the environmental impact of reagents remains a major challenge in phosphate ore beneficiation. Conventional depressants often exhibit limited selectivity and may pose environmental concerns, highlighting the need for sustainable alternatives. This study reports, for the first time, the application of starch nanostructures derived from potato pulp processing residues as a depressant in phosphate flotation, representing an innovative and eco-friendly approach. An exploratory and experimental methodology was adopted, including nanostarch synthesis via acid hydrolysis followed by centrifugation and sonication, as well as comprehensive physicochemical characterization. The primary objective was to evaluate the selective depressant performance of the nanomaterial in apatite–calcite flotation systems. The synthesized nanostructures exhibited particle diameters ranging from 179 to 443.6 nm. Microflotation tests conducted in a Hallimond tube using pure mineral samples under alkaline conditions (pH ≈ 9), at a depressant dosage of 500 mg/L and in combination with a plant-based fatty acid collector, revealed a pronounced selectivity window, resulting in an approximately 77% difference in flotation recovery between apatite and calcite. These findings demonstrate that nanostarch derived from agro-industrial residues is a promising, biodegradable, and sustainable depressant capable of enhancing selectivity in phosphate flotation. The results contribute to the advancement of greener mineral processing Technologies, although Further studies are required to elucidate the underlying interaction mechanisms. Full article

The reagent regime is a key means to regulate mineral flotation behavior, with collectors being particularly crucial for enhancing the flotation process. This paper systematically investigates the action mechanisms of hydrocarbon oil components such as n-Nonane, n-Dodecane, n-Tridecane, n-Tetradecane, and n-Pentadecane in coal slime flotation through a combined approach of molecular dynamics simulation and experimental verification. The simulation results show that as the alkane chain length increases, the absolute value of the adsorption energy between the alkane and coal gradually increases (the adsorption energy is negative, indicating that the adsorption process can occur spontaneously), with n-Pentadecane exhibiting the highest adsorption energy. Experimentally, the oil–water mixture achieved optimal dispersity after ultrasonic treatment and standing for 10 min. This dispersity is characterized by the average oil droplet diameter and the most uniform droplet size distribution under the test conditions. The wetting heat test further verified that pentadecane exhibits the strongest interaction with coal slime and the fastest adsorption rate. In flotation tests, n-Tetradecane demonstrated the best actual flotation performance, with a clean coal yield of 70.88%, a combustible recovery of 82.55%, and a flotation perfection index of 50.75%. This study reveals the influence mechanism of alkane chain length on coal slime flotation behavior, providing a theoretical basis for the screening and compounding of efficient collectors. Full article

Efficient froth flotation of fine smithsonite from slime-containing zinc oxide ores remains challenging due to low particle–bubble collision efficiency and strong surface hydration. Conventional agglomeration methods suffer from high reagent costs, non-selective agglomeration, or reduced surface hydrophobicity. Herein, non-hydrolyzable alkali metal salts, exemplified by NaCl, were introduced as novel and efficient coagulants to enhance the flotation of fine smithsonite, and the underlying mechanisms were systematically elucidated. In the sodium oleate flotation system, alkali metal ions promoted the formation and agglomeration of oleate micelles. Meanwhile, they significantly facilitated collector adsorption onto the smithsonite surface and improved the hydrophobicity of the mineral particles. At high ionic strengths, compression of the electrical double layer reduced the Zeta potential and interparticle electrostatic repulsion. These synergistic mechanisms promoted the growth and stability of hydrophobic aggregates, increasing their collision and attachment efficiency with bubbles. By employing non-hydrolyzable salts, the loss of surface hydrophobicity typically induced by conventional hydrolyzable coagulants was avoided. Validation tests on an industrial zinc oxide ore confirmed the feasibility of this approach, offering a promising pathway to mitigate zinc resource losses and associated environmental hazards. Full article

Overtopping wave energy converters share a similar geometry with traditional slope-ramp breakwaters, allowing integrated development that simultaneously ensures the basic protection function of the structure and realizes wave energy absorption. This study proposes a dual-level overtopping wave energy converter (DULOW) integrated with a pier-type slope-ramp breakwater, specifically designed for oceanic environmental conditions characterized by smaller wave heights and larger tidal ranges. An experimental laboratory investigation was conducted in a wave tank to evaluate the overtopping performance of the DULOW model under regular and irregular wave conditions. The experimental results show that the overtopping discharge increases with the number of plane collectors, and that the discharge collected by the plane collectors is significantly larger than that of the quadrant cone collector. At the higher still water level, the presence of the lower collector reduces the overtopping discharge captured by the high-level collectors. Under irregular wave conditions, the averaged overtopping discharges are lower than those observed under regular wave conditions. Furthermore, a semi-empirical formula is proposed to describe the variation trend of overtopping discharge with effective crest freeboard for the tested DULOW configuration. Full article

This study analyzes the impact of thermal and electrical storage solutions coupled with Photovoltaic (PV) and Concentrating Solar Power (CSP) plants, proposing an innovative model to test a Hybrid Energy Storage System (HESS). The work presents an innovative Mixed Integer Linear Programming (MILP) model to determine the optimal configuration and operational strategy of a HESS within a grid-connected Microgrid (MG). The research focuses on the synergistic integration of PV with Lithium-ion Electrical Energy Storage (EES) and CSP with Thermal Energy Storage (TES). The MG includes dynamic residential, commercial, and hospital loads. The MILP model is optimized over a 24 h horizon across four season-representative days, utilizing a multi-criteria objective function that balances economic performance and CO₂ emissions via a weighting factor ω ∈ [0, 1]. Three distinct CSP options such as Parabolic Trough Collectors with varying Heat Transfer Fluids (molten salt or thermal oil) and TES types (direct and indirect dual-tank, or Phase Change Material) are analyzed, each coupled with a Rankine or Organic Rankine Cycle. Key constraints address energy balances, component efficiencies, power limits, and storage dynamics. The comprehensive results identify the most suitable technology portfolio mix and optimal hour-by-hour operational rules, providing transparent decision-making criteria based on storage size, process temperatures, and specific demand profiles. Full article

Manganese dioxide (MnO₂) modified biochar catalysts derived from biomass and waste polymer feedstocks were synthesized and evaluated as heterogeneous Fenton-like catalysts for solar-driven degradation of Rhodamine B (RhB) in aqueous systems. Biochars produced from maple wood and plastic waste (high-density polyethylene) provided porous carbon matrices with oxygen-rich surface functionalities that enabled effective MnO₂ loading and catalytic activity. Photocatalytic experiments conducted under real sunlight using a solar-collector reactor demonstrated faster RhB degradation compared to a conventional ultraviolet (UV) system, confirming the advantage of solar-driven operation. Complete RhB removal was achieved at initial concentrations of 100–300 ppm, whereas higher dye concentrations (500 ppm) exceeded the catalytic capacity within the tested reaction time. Kinetic analysis revealed catalyst-dependent reaction behaviors, indicating that degradation pathways were strongly influenced by the biopolymer-derived carbon structure and MnO₂ dispersion. Degradation efficiency was correlated with solar irradiance and reactor temperature, with higher UV index conditions enhancing catalytic performance. Reusability tests showed that the catalysts remained active over multiple cycles, although gradual decreases in reaction rates and catalyst recovery were observed. These results demonstrate the potential of biopolymer-derived carbon materials as effective solar-driven catalysts for wastewater treatment applications. Full article