Search Results (3,075)

This study investigates the hydrometallurgical recovery of valuable metals from copper shaft furnace dust (SFD), a complex industrial waste containing approximately 40 wt.% Zn, 16 wt.% Pb, and 1 wt.% Cu. In contrast to conventional inorganic leaching processes that rely on aggressive acids and bases, this research explores the use of deep eutectic solvents (DESs) as eco-friendly and selective lixiviants. Deep eutectic solvents based on choline chloride combined with citric acid and lactic acid were evaluated as leaching media for metal recovery from SFD. The effects of temperature, leaching time, stirring intensity, and the DES:SFD ratio on metal extraction were systematically investigated. Analytical characterization of the raw material, leaching residues, and pregnant leach solutions was performed using Atomic Absorption Spectroscopy (AAS), X-ray Fluorescence Spectrometry (XRF), and Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM–EDS). The experimental results demonstrated efficient recovery of Zn, Pb, Cu, and Sn under mild leaching conditions. For the citric acid–choline chloride system, the highest extraction efficiency was obtained at 60 °C using a DES:SFD ratio of 30, whereas increasing the temperature to 70–80 °C did not significantly improve metal extraction. The lactic acid–choline chloride system exhibited different leaching behaviour, with the highest recoveries achieved after short leaching times. These findings indicate that DES-based systems represent a promising, sustainable alternative for the selective leaching of heavy metals such as Zn, Pb, Cu, and Sn, from metallurgical secondary raw materials, contributing to the development of greener circular economy practices. Full article

Metal–organic frameworks (MOFs) have emerged as a versatile class of porous nanomaterials with exceptional surface area, tunable pore architectures, and customizable chemical functionalities, creating new opportunities for advanced food applications. Increasing demand for functional foods, precision fermentation, and sustainable bioprocessing has stimulated interest in MOFs as multifunctional platforms for microbial encapsulation, biocatalyst stabilization, and resource recovery. This review examines recent advances in the design and application of MOFs for probiotic delivery, precision fermentation, and circular food systems. The relationships between MOF structure, physicochemical properties, and functional performance are discussed in the context of probiotic encapsulation, protection against environmental and gastrointestinal stress, and controlled release within the intestinal tract. Emerging applications in precision fermentation are evaluated, including microbial immobilization, enzyme stabilization, metabolite separation, and bioprocess intensification. The potential of MOFs to enable circular food systems through the valorization of fermentation by-products, nutrient recovery, and waste-to-value strategies is also assessed. Despite significant progress, challenges related to biocompatibility, food-grade synthesis, scalability, regulatory approval, and long-term safety continue to limit industrial implementation. Future research directions include the development of sustainable and biodegradable MOFs, data-driven material design, and standardized evaluation frameworks to accelerate the translation of MOF-enabled technologies from laboratory research to commercial food applications. Full article

Heat pumps are core equipment for efficient low-grade thermal energy utilization and low-carbon transformation of the energy structure, offering significant energy-saving potential in building heating and industrial waste heat recovery. This paper reviews the research progress and technical challenges of compression, absorption, and adsorption heat pumps as well as nanofluid-enhanced heat transfer technology and elastocaloric heat pump systems. Air source heat pumps can delay frosting through variable frequency, heat storage, and waste heat recovery. However, accurate prediction models for performance degradation under extreme cold conditions are lacking. Although ground source and water source heat pumps exhibit significant energy efficiency advantages, ground source systems may suffer from performance degradation due to underground thermal imbalance. The application of water source systems is strictly constrained by water resource conditions. Driven by low-grade waste heat, absorption heat pumps employing traditional working pairs suffer from crystallization, corrosion, or high rectification energy consumption. The COP of a single-effect cycle under 80~100 °C waste heat is only 1.2~1.9, while hybrid cycles can reach approximately 3.2 at 120~150 °C. Although adsorption heat pumps achieve significantly improved performance under continuous heat recovery cycles, the full-scale power density of novel adsorbents such as metal–organic frameworks is inferior to the power density of traditional silica gel. Moreover, under off-design conditions, the performance drops by 23~48% compared to theoretical values. Nanofluids can enhance heat transfer, but the long-term effects of particle agglomeration at high temperatures on pump power consumption and system compatibility remain to be systematically evaluated. Elastocaloric heat pump systems can achieve refrigerant-free cooling, but current prototypes still cannot compete with traditional vapor compression systems in long-cycle fatigue reliability and power density. Current heat pump technologies generally face challenges such as insufficient adaptability to extreme conditions, bottlenecks in working fluids and materials, and a lack of long-term validation. Future research must construct a multi-source coupling optimization system, address common problems in working fluids and materials, promote long-term validation and kilowatt-level prototype demonstrations, and drive the large-scale deployment and engineering application of heat pump technology toward high efficiency, intelligence, and high reliability. Full article

Hydrodesulfurization (HDS) is a critical technology for producing clean petroleum products. With the steady growth in annual crude oil processing volumes, the consumption of HDS catalysts has been continuously increasing. The massive release of spent catalysts imposes significant pressure on both the environmental compliance and sustainable operation of companies. Spent HDS catalysts contain relatively high concentrations of valuable metals such as Mo, Ni, V, and Co. These materials are toxic and harmful heavy metal pollutants, yet they also constitute an important secondary resource of strategic metals with extremely high recycling value. Based on a systematic comparison of relevant recovery technologies, this paper reviews the current status of valuable metal recovery from spent HDS catalysts. It summarizes typical process routes for the full-component recovery of valuable metals and discusses future research directions, with the aim of providing a theoretical reference for the high-value resource utilization of spent HDS catalysts. Full article

The growing demand for rare earth elements (REEs), heavy metals (HMs) and precious metals (PMs) has intensified interest in sustainable recovery strategies from secondary resources, including mining residues, industrial effluents and waste electrical and electronic equipment (WEEE). These streams represent exposure interfaces, because soluble and bioavailable metal species may persist, bioaccumulate and contribute to oxidative stress, genotoxicity, carcinogenic outcomes and chronic systemic effects. This systematic review, conducted following PRISMA guidelines, evaluates the thermoacidophilic red microalga Galdieria spp. as an extremophilic platform for metal bioremediation, recovery and upstream risk reduction. Galdieria spp. combines tolerance to low pH, elevated temperature and high metal loads with rapid surface biosorption and, in living biomass, slower intracellular sequestration and detoxification. Its interaction with REEs, PMs and toxic HMs is mediated by cell-wall functional groups, extracellular polymeric substances, redox-active processes and metabolic flexibility shaped partly by horizontal gene transfer (HGT). The review discusses matrix complexity and adsorption–desorption cycles, highlighting their implications for real industrial streams. Overall, Galdieria spp. emerges as a robust extremophilic bio-interface for selective metal recovery, hazardous waste mitigation, circular-economy biorefinery models and prevention of metal-associated risks to environmental and human health, while current scale-up limitations and process-oriented research priorities are identified. Full article

Background: Non-missile penetrating traumatic brain injury (pTBI) is a rare but life-threatening condition. In self-inflicted cases involving the frontal sinus, a rigorous preoperative diagnostic workup is crucial to assess foreign body fragmentation, trajectory, and potential vascular compromise. The complexities of such cases demand a highly structured approach to prevent severe secondary brain injury and long-term infectious sequelae. Case Presentation: A 36-year-old male with schizophrenia presented after attempting suicide by stabbing a kitchen knife through his frontal sinus. Multimodal diagnostic imaging was immediately employed. Skull radiographs and computed tomography (CT) precisely delineated the blade traversing the frontal sinus and entering the anterior cranial fossa. Crucially, given the proximity to the skull base, digital subtraction angiography (DSA) was proactively performed, which confirmed the absence of major cerebrovascular injury and safely guided the surgical strategy. Based on these precise imaging findings, a bifrontal craniotomy was performed. During the procedure, the main blade was extracted, and a retained broken metallic tip—recognized upon close intraoperative inspection of the extracted blade—was successfully retrieved from the intracranial compartment. Postoperative wound infections (with causative pathogens isolated as Serratia odorifera and coagulase-negative Staphylococci) were effectively eradicated with targeted antibiotics. The patient achieved a favorable neurological recovery. Conclusions: Multimodal neuroimaging, particularly the combination of CT and DSA, can be highly beneficial in the diagnostic workup of complex pTBI. Precise preoperative imaging helps guide the optimal surgical approach, ensuring complete foreign body removal and minimizing severe secondary complications. Early intervention, guided by standardized imaging and followed by aggressive medical management, can yield positive outcomes even in severely morbid presentations. Full article

Neodymium (Nd) and dysprosium (Dy) are two critical rare earth elements for fabricating NdFeB permanent magnets, which have crucial applications in modern technologies. The increasing global demand for Nd and Dy emphasizes new efficient processes for their recovery and purification, which are technologically challenging due to their close physical and chemical properties. Through systematic exploration, it was found that Lewatit VP OC 1026 resin impregnated with di-(2-ethylhexyl) phosphoric acid (D2EHPA) had a strong adsorption preference for Dy³⁺ over Nd³⁺, which is highly suitable for Dy-Nd separation from their mixed solutions under optimized conditions. The loaded resin could be eluted using dilute sulfuric solutions for recycling to the adsorption process. By employing a multistage adsorption-elution process analogous to distillation, efficient Dy-Nd separation and purification were realized from their mixed solution, with a prospective purity of 99.13% and recovery of 97.45% for Dy and a prospective purity over 99.96% and recovery of above 99.90% for Nd, despite the large concentration disparity between Dy and Nd, where Nd concentration is over 26 times that of Dy. This research demonstrates that efficient recovery and purification of metals from aqueous solutions can be achieved using selective resin adsorption processes analogous to distillation, despite large concentration differences of the metals in the solutions, which presents new alternative approaches. Full article

Vanadium–titanium-bearing direct reduced iron (V-Ti DRI) is a promising feedstock for the full-value utilization of V-Ti magnetite. Selective partition of V and Cr into the metal phase, with Ti retained in the slag, requires quantitative thermodynamic guidance. We investigate this slag–metal distribution using the ion and molecule coexistence theory (IMCT). An eight-component slag model with 33 complex-molecule equilibria is coupled to reduction thermodynamics through an iterative mass-balance procedure; the metal-phaseWagner activity is temperature-scaled by Chipman’s rule, and the dissolved oxygen concentration is closed through the C-CO-O equilibrium. The equilibrium V and Cr recovery ceilings (metal side) rise from 89%/96% at 1400 °C to approximately 99.4% at 1500 °C and exceed 99.8% at 1550 °C. Ti-in-slag retention (slag side) drops steadily from 99.998% at 1400 °C to 99.4% at 1700 °C, giving a V/Ti separation factor above 104. Fe recovery to the metal phase exceeds 97% at 1600 °C and above, driven by the strong reduction of FeO, which constitutes approximately 32 wt.% of the initial slag. Carbon activity exerts a cubic power-law effect: at 1450 °C, the V recovery ceiling collapses from 97.4% at a_C = 1 to 6.5% at a_C = 0.05, identifying imperfect carbon saturation as a primary thermodynamic mechanism behind the ceiling-to-pilot gap. Once temperature and oxygen closure are enforced, the ceilings are only weakly sensitive to metallization, basicity, coke ratio, and TiO₂ content. Comparison with pilot data shows the ceilings exceed reported yields by 16–29 percentage points (pp), quantifying the kinetic/mass-transfer deficit and providing a benchmark for scale-up. Full article

Reaching the end of their lifecycle, lithium-ion batteries contain significant amounts of lithium residues as well as valuable metals such as Co, Ni, and Mn, presenting both environmental risks and opportunities for resource recovery. Recent advances in hydrometallurgical, pyrometallurgical, and biotechnological methods enable the recovery of high-purity lithium compounds while also increasing their economic viability. This study analyzes the contribution of lithium recovery methods to sustainability criteria, their annual averages, and total data between 2008 and 2026, considering the number of academic references in the literature. The analysis compares the contributions of recycling methods to lithium and other metal recovery efficiency, process efficiency, energy consumption, environmental impact, economic impact, adaptation to technological developments, and integrated applications. LIB recycling methods showed higher overall and annual average sustainability contributions to the recovery efficiency of other metals and lithium compared to other criteria. Their contributions to process efficiency and the environment were also relatively high. However, their contributions to the economy, adaptation to technological developments, and integration of methods remain low. Furthermore, since the contribution to energy consumption is negative overall, further academic studies are needed to improve contributions, particularly in energy consumption and the other three criteria mentioned above. Full article

The transport of metal ions from highly saline matrices remains challenging due to the elevated ionic strength and complex chemical speciation that characterize seawater and desalination brines. In this work, the influence of membrane composition on Cd(II) transport through polymer inclusion membranes (PIMs) was evaluated using cellulose triacetate (CTA), poly(vinyl chloride) (PVC), and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membranes containing Aliquat 336. Membranes were tested using model NaCl solutions, seawater, and desalination brine, and the effects of membrane mass, polymer matrix, carrier/plasticizer composition, and receiving phase were investigated. Reducing the CTA membrane mass by 50% did not significantly affect transport efficiency, indicating that membrane composition had a greater influence on Cd(II) transport than membrane mass under the conditions evaluated. Among the evaluated formulations, the optimum PVDF-HFP membrane contained 60 wt.% PVDF-HFP, 30 wt.% Aliquat 336, and 10 wt.% butyl stearate (BTS), achieving a transport efficiency of 95.5% and an initial flux of 2.7 × 10⁻⁶ mol m⁻² s⁻¹ in desalination brine. The use of 0.5 M HNO₃ as the receiving phase markedly improved Cd(II) transport in both synthetic saline solutions and real seawater and desalination brine compared with ultrapure water. These results highlight the importance of polymer–plasticizer interactions in controlling Cd(II) transport and demonstrate the potential of PVDF-HFP/Aliquat 336/BTS membranes for metal recovery from complex saline media. Full article

Reliable visual identification of household gas facilities is important for safety inspection, yet images acquired in real indoor environments are frequently affected by cluttered textures, shadows, metallic reflections, stains, dust, motion blur, occlusion, and viewpoint variation. In RT-DETR, these conditions can weaken cross-scale structural cues, reduce the ranking of small-object candidates, and amplify localization errors under strict IoU criteria. We hypothesize that coordinated intervention at feature fusion, query allocation, and box regression can alleviate this coupled failure process without enlarging the decoder-query budget. Accordingly, DRQ-RTDETR integrates degradation-aware detail recovery, small-object-guided query selection, and scale-adaptive geometric refinement. Experiments on a real household gas facility dataset containing 21,813 images and 47,169 instances across eight safety-related categories show that DRQ-RTDETR improves mAP from 0.6168 to 0.6576, mAP50 from 0.7909 to 0.8124, mAP75 from 0.6702 to 0.7136, and mAPsmall from 0.4639 to 0.5247 relative to RT-DETR. The larger gains in mAPsmall and mAP75 indicate that the proposed coordination is particularly effective for weak-response compact components and boundary-sensitive localization in degraded household scenes. Full article

This study presents a novel, low-temperature thermochemical activation process for the selective extraction of Cr and V from carbon steel EAF (CH1) and FeCr (CH2) slags at temperatures of up to 600 °C. Of the twelve reagents tested, NaOH was identified as the optimal alkaline agent for Cr activation at 500 °C, achieving extraction yields of 61.6% for CH1 (slag-to-reagent ratio of 12:8 g) and 80.6% for CH2 (ratio of 12:16 g). KOH at 400 °C was the most effective reagent for V extraction, yielding 89.4% for CH1 and 54.5% for CH2. Maximum metal concentrations were achieved after only five minutes of leaching at 60 °C. The process exhibits high selectivity; primary matrix components (Fe, Si, Al, Ca, Mg) either do not leach or only leach in negligible amounts. Iron forms insoluble oxides, and calcium converts into stable calcite, while magnesium is bound in the form of hydrotalcite specifically in the CH2 slag leaching residue. The CaCO₃ content was proven to be a crucial parameter determining the activation efficiency and effective transformation of Fe-Cr-V phases. This procedure enables the recovery of clean Cr and V leachates, while the residual mineral-rich fraction offers potential for various industrial applications in a closed-loop slag recycling process. Full article

Industrial effluents containing zinc, cadmium, and nickel represent both an environmental challenge and a valuable secondary resource. This study investigates the simultaneous recovery of Zn(II), Cd(II), and Ni(II) from nitric acid solutions using di-(2-ethylhexyl) phosphoric acid (D2EHPA) dissolved in commercial diesel fuel in a continuous counter-current semi-pilot mixer–settler extraction system. The effects of key operating parameters, including aqueous-phase pH, initial metal concentration, phase ratio, contact time, stirring speed, and stripping agent, were systematically evaluated. Metal concentrations were determined by atomic absorption spectrometry, while Fourier-transform infrared spectroscopy was employed to investigate the extraction mechanism. The optimum operating conditions were pH 2.45 for Zn(II) and pH 5.38 for Cd(II) and Ni(II), a phase ratio of V_A/V_O = 1.5/3.5, and a stirring speed of 700 rpm. Under these conditions, high extraction efficiencies were achieved, with Zn(II), Cd(II), and Ni(II) recoveries of 98.52%, 76.86%, and 84.04%, respectively. FTIR characterization, together with slope analysis, suggested a dimeric cation-exchange extraction mechanism involving D2EHPA species in the organic phase. Among the stripping agents evaluated under the present experimental conditions, 0.5 M H₂SO₄ produced the highest stripping efficiencies for Zn(II), Cd(II), and Ni(II). Although the stripping efficiencies remained moderate, particularly for Cd(II) and Ni(II), these results demonstrate the relative effectiveness of H₂SO₄ compared with the other stripping agents examined. Further optimization of the stripping conditions is expected to improve metal recovery. The proposed process shows significant potential for industrial wastewater treatment, metal recovery, and resource valorization. Full article

The rapid increase in electric vehicles has increased the generation of spent lithium-ion batteries (LIBs) and the need for efficient lithium recovery technologies. This study compared two distinct sulfation roasting routes, using sodium sulfate (Na₂SO₄) at 750 °C and sulfuric acid (H₂SO₄) at 550 °C, applied to black mass derived from lithium iron phosphate (LFP) and lithium nickel manganese cobalt oxide (NCM) batteries. Metal extraction efficiencies were determined by inductively coupled plasma optical emission spectrometry, while reaction products were identified by X-ray diffraction analysis. Sulfation roasting using Na₂SO₄ resulted in low lithium recovery for both materials, with maximum extractions of 5.7% for LFP and 24.5% for NCM. In contrast, H₂SO₄-assisted roasting achieved high lithium recovery from NCM black mass, reaching 90.8%, 91.5%, and 88.5% at 45, 90, and 180 min at 550 °C, respectively, with lithium predominantly converted into water-soluble lithium sulfate. Lithium extraction from LFP black mass remained below 13% under all conditions. Statistical analysis confirmed that lithium recovery at 45 min was equivalent to longer residence times, while prolonged roasting increased manganese coextraction and altered cobalt and nickel behavior. Overall, sulfuric acid-assisted sulfation roasting is an efficient and energy-favorable route for lithium recovery from NCM black mass, whereas sulfation roasting is unsuitable for LFP materials, under the tested conditions. The results highlight the importance of cathode chemistry segregation and demonstrate the feasibility of reducing processing time without compromising lithium recovery. Full article

A simple and cost-effective graphite paste electrode modified with 5-(4-aminophenyl)-4-amino-1,2,4-triazole-3(2H)-thione was developed for the selective voltammetric determination of Cu(II) ions in environmental water samples. The N,S-donor ligand was incorporated into a graphite–polystyrene matrix without the use of nanomaterials, providing a reproducible and straightforward electrode fabrication route. Scanning electron microscopy revealed a rough, porous surface morphology with an enhanced electroactive surface area of 0.065 cm², approximately twice the geometric area. Electrochemical impedance spectroscopy confirmed diffusion-controlled mass transport, while cyclic voltammetry indicated quasi-reversible behaviour of the Cu(II)/Cu(0) redox system with a linear dependence of peak current on the square root of the scan rate. Differential pulse voltammetry under optimised conditions (0.1 mol·L⁻¹ H₂SO₄, pH 1.0–1.2) yielded a linear analytical response over the concentration range of 0.01–0.4 μmol·L⁻¹ (R² = 0.99507), with a limit of detection of 0.02 μmol·L⁻¹ and a limit of quantification of 0.06 μmol·L⁻¹—well below the WHO guideline for copper in drinking water. The sensing mechanism involves selective N,S-bidentate coordination of Cu(II) at the electrode surface, followed by electrochemical reduction, as supported by FT-IR spectroscopic evidence. The sensor demonstrated good selectivity toward Cu(II) in the presence of common interfering metal ions at up to 20-fold excess. The method was successfully validated against ICP-OES (recovery 99.8%, RSD < 0.33%) and confirmed by spike–recovery experiments (99.0–99.5%), confirming its practical applicability for trace-level environmental monitoring. The modified electrode retained approximately 93% of its initial response after 30 consecutive measurements and 91% after 14 days of storage, demonstrating good operational stability. Full article