Capture Mechanism Research Articles

Temporary changes in current flow mechanisms in erbium-doped porous silicon

The paper discusses the basic mechanisms of conductivity in silicon MIS structures. The object of the study is porous silicon doped with an erbium impurity of an aqueous solution of erbium nitrate Er(NO3)3 • 5H2O by temperature annealing in a diffusion furnace at a temperature of 800°C for 1 hour. Comparative characteristics of the current-voltage and capacitance-voltage dependences are presented, describing the regular changes in the mechanisms of current flow and charge capture in the samples under study. The results of the work qualitatively and quantitatively describe the temporary change in the electrical characteristics of porous silicon, which can be taken into account by technologists for better understanding the mechanisms of current transfer in luminescent structures of porous silicon with erbium ions, as well as in the study and manufacture of light-emitting diodes based on it.

Perceptual localization and focus refinement network for RGB-D salient object detection

RGB-D salient object detection task still encounters three challenges: (1) how to effectively integrate superior information from different modalities, (2) how to effectively mine common information of features at different levels, and (3) how to detect salient objects in complex scenes, such as complex backgrounds, low-quality depth maps, small targets, and high foreground-background similarity. To address the above challenges, we propose a novel Perceptual Localization and Focus Refinement Network, termed PLFRNet, based on the mechanism of human visual capture of salient objects in images. The network includes three key components: an encoder, a Perceptual Localization Module (PLM), and a Focus-Refinement Decoder (FRD). Specifically, we first adopt a two-stream asymmetric Pyramid Visual Transformer as the encoder to extract RGB and depth features. Then, we develop the PLM under the guidance of a Perceptual Localization Unit (PLU) delicately designed. This module can mine the common information of features at different levels and integrate the advantageous information from multiple modalities to localize salient objects. Finally, we propose the FRD focusing on detailed information guided by the attention mechanism. Furthermore, it further refines the located objects by gradually interacting with low-level features to achieve salient object detection. Extensive experimental results show that this method achieves state-of-the-art performance compared with 13 RGB-D models on 6 public datasets. The codes are released at https://github.com/hjy0518/PLFRNet/.

Carbon capture characteristics and mechanisms of municipal wastewater treatment using coagulation-enhanced HRCS system

This study optimized coagulation in HRCS systems for municipal wastewater treatment, investigating coagulant dosage effects on carbon capture and microbial communities. Real wastewater testing in coagulation-enhanced HRCS (CE-HRCS) systems further revealed carbon capture efficiency and microbial mechanisms, enhancing resource utilization. The results demonstrated that with a coagulant dosage of 20 mg/L, the combined proportion of Proteobacteria and Bacteroidetes, the pivotal bacteria for carbon capture, exceeded 90 %. This dosage achieved a maximum sludge extracellular polymeric substance (EPS) content of 150 mg/g VSS and a carbon capture efficiency of 83 %. Upon transitioning to real municipal wastewater, while the chemical oxygen demand (COD) removal rate slightly dipped to approximately 80 %, the carbon capture rate remained robust at 63 ± 2 %, down from 70 %. The EPS content stabilized at 138 ± 2 mg/g VSS, indicating a satisfactory carbon capture efficiency for practical municipal wastewater treatment. Moreover, the microbial population in the CE-HRCS system exhibited an increase in species richness and diversity. Although the proportion of Proteobacteria declined from 83 % to 62 %, the presence of Firmicutes and Bacteroidota increased, with carbon degradation-related functional bacteria continuing to dominate. This study offers valuable insights and new guidance for enhancing carbon capture from municipal wastewater using CE-HRCS technology.

Investigating the microscopic enhancement mechanisms of adsorption-based CO2 capture with Cu-loaded γ−Al2O3 using density functional theory

Transition-metal-loaded γ−alumina (Al2O3) is considered to be an effective adsorbent for CO2 capture, but its microscopic process and mechanisms of CO2 adsorption are not fully understood. To investigate the microscopic enhancement role of Cu atoms in CO2 adsorption, this work compares various adsorption configurations and parameters of CO2 on γ−Al2O3 (110) facets with or without Cu atoms and small Cu cluster loading (Cun (n=1,2,3)/γ−Al2O3) using the first-principles approach. According to the adsorption energy, charge transfer, difference charge density, and other parameters of different configurations, the γ−Al2O3 (110) slab loaded with the Cu atom is found to exhibit enhanced adsorption of CO2 molecules compared to that without Cu loading. Moreover, the surface stability increases with the number of loaded Cu atoms. However, the hydroxyl groups in the active sites partially undermine the adsorption effect during the CO2 adsorption process. The density of states indicates that the doping of Cu atoms in the system creates an orbital peak closer to the Fermi energy level. This facilitates the transfer of charge within the slab, making the activation of CO2 easier and promoting stable adsorption. Finally, the amount of crystal orbital overlap population and crystal orbital Hamilton population shows that the stability of adsorption is due to the formation of C-Cu and C-Al bonds. It is demonstrated that the Cun-loaded γ−Al2O3 (110) slab improves the adsorption performance and contributes to a better understanding of the effect of transition-state metal loaded γ−Al2O3 on CO2 adsorption.

A blueprint for success? Exploring business models of additive manufacturing ventures

Additive Manufacturing (AM) was expected to be the next great technological revolution, yet the predicted market growth has fallen short by 40%. Using a proprietary, cross-sectional data set of 350 ventures in the AM field founded between 2000 and 2017, this study analyses AM companies from a business model perspective. Specifically, we explore which value delivery and value capture mechanisms are decisive for AM venture success, measured via their operational and ownership state. We reveal that targeting the B2B market and selling via partner networks significantly increases firm survival likelihood. Further, applying a recurring revenue model increases the likelihood of an IPO. Our main contributions are two-fold: first, our research complements the business model literature by evaluating value delivery and capture in the AM entrepreneurial space, revealing that customer segments, sales channels, and revenue models are key to venture success. Second, we provide business model design guidelines to entrepreneurs as well venture capitalists in the AM field.

Simultaneous utilization of copper and non-metals from waste integrated circuits for precious metal melting capture and organics thermal detoxification

Waste integrated circuits, with underlying resource attributes and environmental risks, are complex in composition. Current processes suffer from high resource inputs, excessive pollutant emissions and incomplete treatment of varied species. Therefore, a comprehensive resource recycling and safe disposal process integrated with precious metal enrichment, non-metal resource utilization, and organic detoxification was proposed. The copper and non-metals from waste ICs served as in-situ precious metal collector, slagging former and reducing agent for alternative to partial chemical inputs. Batch experiments indicated that optimized parameters enabled the recycling efficiencies of 94.3 %, 96.8 % and 98.4 % for copper, gold and silver, respectively. Meanwhile, oxide component, yielded as silicate slag, was synthesized into glass ceramics via high-temperature sintering. Furthermore, organic conversion process revealed that high-temperature smelting catalyzed bromine removal and contaminant detoxification, with decomposed reductive hydrocarbons facilitating metal capture in turn. And the capture mechanism was disclosed form thermodynamics and microdroplet motion perspectives. As process evaluation indicates, proposed recycling route allows remarkable reductions in negative environmental response and economic investment. In this work, metal recycling, waste minimization and pollutant detoxification were attained synergistically without residue, which contributes a novel insight into the disposal of comparable e-wastes.

Charge Carrier Capture by Prominent Defect Centers in 4H-SiC

The knowledge of capture properties of electrically active defects is of primary importance as it helps to understand which deep states are effective in controlling the excess free carriers’ lifetime. Combining DLTS capture experiments with thermal emission measurements enables an overall thermodynamic description of deep states, thus making it possible to characterize recombination centers in semiconductor-based devices. In the present study, junction DLTS capture rate measurements were employed to extract the true capture cross-sections (inversely proportional to the carrier lifetime) and capture energy barriers for the main lifetime limiting defects in 4H-SiC (silicon carbide). A peculiar forward bias dependence of the capture parameters was observed for the shallow boron (B) hole trap. Capture rate measurements on the deep boron (D-center) trap also evidenced the presence of two capture mechanisms, thus allowing discrimination of D1 and D2 deep states within the D-center DLTS peak. The results were combined with activation energies and apparent capture cross-sections to obtain the free energy (ΔG) of electronic activation for the analysed deep states.

A novel ionic liquids phase change absorption system for carbon dioxide capture and utilization

In order to achieve low cost, and reduce energy consumption during regeneration, a novel ionic liquid phase change absorbent composed of tetraethylenepentamine [TEPA] imidazole [Im] and diethylene glycol dimethyl ether (DGME) and water was designed for CO2 capture applications. The absorbent [TEPAH][Im]+DM+H2O can achieves a CO2 absorption capacity of 2.08 mol CO2/mol ILs, the rich phase volume accounts for 15.6 vol%, and the mass fraction of CO2 is 99 %, this greatly reduces the regenerative volume of the absorption system, showing the potential of energy saving and emission reduction. After five absorption–desorption cycles, the regeneration efficiency of the system remained above 96 %. The CO2 capture mechanism was analyzed using both 13C NMR spectroscopy and density functional theory (DFT) calculations to elucidate its underlying processes. The cation [TEPAH]+ and the anion [Im]- each undergo a reaction with CO2 to produce carbamate, followed by hydrolysis of carbon dioxide to yield carbonate. The absorption system’s phase transition behavior primarily arises from variations in CO2 product solubility across solvents. Moreover, the ionic liquid facilitated the conversion of CO2 into quinazoline-2,4 (1H, 3H)-dione with a remarkable yield of 98 %. Even after five cycles, the ILs maintained substantial catalytic activity.

Differences in Protein Capture by SP3 and SP4 Demonstrate Mechanistic Insights of Proteomics Cleanup Techniques.

The goal of proteomics experiments is to identify proteins to observe changes in cellular processes and diseases. One challenge in proteomics is the removal of contaminants following protein extraction, which can limit protein identifications. Single-pot, solid-phase-enhanced sample preparation (SP3) is a cleanup technique in which proteins are captured on carboxylate-modified particles through a proposed hydrophilic-interaction-liquid-chromatography (HILIC)-like mechanism. Recent results have suggested that proteins are captured in SP3 due to a protein-aggregation mechanism. Solvent precipitation, single-pot, solid-phase-enhanced sample preparation (SP4) is a newer cleanup technique that employs protein aggregation to capture proteins without modified particles. We hypothesize that differences in capture mechanisms of SP3 and SP4 affect which proteins are identified by each cleanup technique. Herein, we assess the proteins identified and enriched using SP3 versus SP4 for MCF7 subcellular fractions and correlate protein capture in each method to protein hydrophobicity. Our results indicate that SP3 captures more hydrophilic proteins through a combination of HILIC-like and protein-aggregation mechanisms, while SP4 captures more hydrophobic proteins through a protein-aggregation mechanism. Ultimately, we demonstrate that protein-capture mechanisms are distinct, and the selection of a cleanup technique that yields high proteome coverage is dependent on protein-sample hydrophobicity. Data has been deposited into MassIVE (MSV000094130) and ProteomeXchange (PXD049965).

Reliability of Continuous Noninvasive Hemoglobin Monitoring in Healthy Participants During En Route Care Training.

Current standards for hemoglobin monitoring during air transports of U.S. combat wounded are invasive and intermittent. Fielded pulse co-oximeters can noninvasively measure total hemoglobin, but this parameter is not currently utilized. The primary objective of this study was to assess the percentage of vital sign measurements with successful capture of total noninvasive hemoglobin measurement using spectrophotometry-based technology for Hb (SpHb) measurements in healthy participants during training flights. Secondary objectives were to assess the feasibility of a novel electronic data capture mechanism from usual patient movement items and perform a pilot analysis of SpHb changes in healthy participants during transitions from ground to air transport. We conducted a feasibility study enrolling healthy participants who had hemodynamic monitoring during usual U.S. Air Force Critical Care Air Transport (CCAT) flight training exercises from 2022 to 2023. Usual CCAT monitoring equipment and currently used Masimo Rainbow® pulse co-oximeters had the capability to measure SpHb. After each training exercise, the study team wirelessly downloaded case files from patient monitors utilizing the Battlefield Assisted Trauma Distributed Observation Kit (BATDOKTM) Case Downloader application. We then calculated point and precision estimates for the percentage of time for successful SpHb capture during the exercise and compared this to pulse oximetry (SpO2) capture. An a priori precision analysis for percentage of flight-time with successful SpHb data capture and descriptive statistics were performed. This study received Exempt Determination by the 59th Medical Wing IRB. We analyzed 26 records with mean monitoring durations of 94.5 [59.3-119.9] minutes during ground phases and 78.0 [59.9-106.5] minutes during flight phases. SpHb measures were successfully captured for 97.7% (n = 4,620) of possible ground measurements and 97.2% (n = 3,973) of possible in-flight measurements compared to 99.5% ground and 98.2% in-flight capture for SpO2. Mean intervals of missing SpHb data were 2 ± 5 minutes on the ground and 4 ± 6 minutes in-flight. Mean SpHb increased by 0.93 ± 0.96 g/dL during the ground phase, but had minimal changes during ascent, cruising altitude or descent. The BATDOKTM Case downloader completed transfer for all files. Masimo Rainbow® SpHb pulse co-oximeters reliably captured continuous, noninvasive hemoglobin measurements using usual CCAT patient movement items in healthy participants during both ground and flight training. The BATDOKTM Case Downloader successfully imported case files from CCAT patient monitors. Mean SpHb measures had a small increase during the ground phase of monitoring followed by minimal changes when transitioning to flight altitude.

Wood aerogel based on PDA-modified rGO mimicking mussel mucin for efficient interfacial evaporation

Solar-driven interface evaporation technology with high thermal localization characteristics has been widely applied in seawater desalination. This paper reports on a highly efficient solar interface evaporator developed by spraying polydopamine (PDA)-modified reduced graphene oxide (rGO) onto the surface of wood aerogel (WA). Dopamine (DA) self-polymerizes in an alkaline medium to form PDA, which acts as a reducing agent and adhesive. Together with rGO as the photothermal layer, PDA and rGO combine through complex cross-linking adhesion to create a three-dimensional evaporation device with vertical channels. Additionally, based on the design of the interface “light trap” structure, the light capture mechanism of the pores was analyzed by simulating the path of incident light. Evaporation experiments were conducted to explore the impact of pore structures on evaporation performance. Under optimal structural parameters (D2H5), the evaporation rate and efficiency reached 1.9325 kg m−2 h−1 and 98 %, respectively. This work demonstrates that PDA-modified rGO wood aerogel (PGW) exhibits excellent evaporation performance and high scalability, which can help alleviate the global shortage of clean water resources.

Immobilization of PCET Materials for Electrochemical pH Swing Driven Carbon Capture

Proton-coupled electron transfer (PCET) is a promising method in the realm of carbon capture and release mechanisms. Its fundamental capacity lies in electrochemically inducing pH swings within an aqueous solution, leveraging the high solubility of carbonates in highly alkaline water to capture CO2 and subsequently release iton demand when the aqueous solution is acidified. PCET-based methods promise higher energy efficiency for carbon capture compared to other electrochemical carbon capture methods because they feature fast charge transfer kinetics and can decouple gas-liquid contact and electrochemical activation. In theory, they also allow the use of cheap, widely available small-molecule PCET agents. However, in practice, PCET agents have shown a key limitation that has, thus far, hindered their scalability: oxygen-induced chemical degradation with continued electrochemical cycling. In this work we mitigate the prevailing issue of oxygen sensitivity by immobilizing PCET agents onto a fabric substrate. Via reactive vapor deposition (RVD), porous and conductive films composed of PEDOT-Cl and poly-aminoanthroquinone (PAAQ) are deposited on the surface of a wool felt blend fabric. This approach resulted in the development of a cost-effective, metal-free, and efficient electrode for both capture and release of CO2. Through electrochemical evaluation, the performance of PCET-active quinone moieties present on PAAQ was measured. The overall efficiency of electrochemical capture from gaseous CO2 was found to be 197 kJ/molCO2, substantiating the efficacy of this novel electrode. This work highlights the potential of fabric-immobilized PCET agents and presents a promising avenue towards a sustainable, efficient, and economically viable approach to carbon capture and release technologies.

Reinforcement-Learning-Based Multi-UAV Cooperative Search for Moving Targets in 3D Scenarios

Most existing multi-UAV collaborative search methods only consider scenarios of two-dimensional path planning or static target search. To be close to the practical scenario, this paper proposes a path planning method based on an action-mask-based multi-agent proximal policy optimization (AM-MAPPO) algorithm for multiple UAVs searching for moving targets in three-dimensional (3D) environments. In particular, a multi-UAV high–low altitude collaborative search architecture is introduced that not only takes into account the extensive detection range of high-altitude UAVs but also leverages the benefit of the superior detection quality of low-altitude UAVs. The optimization objective of the search task is to minimize the uncertainty of the search area while maximizing the number of captured moving targets. The path planning problem for moving target search in a 3D environment is formulated and addressed using the AM-MAPPO algorithm. The proposed method incorporates a state representation mechanism based on field-of-view encoding to handle dynamic changes in neural network input dimensions and develops a rule-based target capture mechanism and an action-mask-based collision avoidance mechanism to enhance the AM-MAPPO algorithm’s convergence speed. Experimental results demonstrate that the proposed algorithm significantly reduces regional uncertainty and increases the number of captured moving targets compared to other deep reinforcement learning methods. Ablation studies further indicate that the proposed action mask mechanism, target capture mechanism, and collision avoidance mechanism of the AM-MAPPO algorithm can improve the algorithm’s effectiveness, target capture capability, and UAVs’ safety, respectively.

Hyaluronic acid mediated ZnO-NPs: In relation to electrical and photocatalytic activity for dye degradation

Various processes have been implemented to purify water; however, photocatalysis is comprehensively utilized in wastewater treatment and plays a significant role in water remediation. A photocatalyst is a nanostructured metal oxide ZnO nanoparticles, which boosts the reaction rate by its existence. ZnO nanoparticles show great performance in the absorption of various organic pollutants from wastewater. The objective of this research was to enhance the photocatalytic degradation performance of HA-added ZnO NPs using methylene blue as a model wastewater. Adjusting the main physical properties and photocatalytic efficiency of ZnO-NPs was performed using hyaluronic acid (HA), a natural bioactive stabilizer. The characterization of the fabricated ZnO-NPs samples with and without HA involved the utilization of FE-SEM, AFM, XRD, FTIR, PL, and I-V. As demonstrated by the FE-SEM analysis, ZnO formed rod-like structures, 3.0 % HA:ZnO exhibited cauliflower-like structures, and 5.0 % HA:ZnO displayed honeycomb-like structures. The X-ray diffraction (XRD) analysis demonstrated that the HA:ZnO nanoparticles exhibited hexagonal wurtzite structures. The average crystallite sizes of the ZnO, 3.0 % HA:ZnO, and 5.0 % HA:ZnO NPs were determined to be 25.20, 27.30, and 20.20 nm, respectively, using the XRD patterns. The surface area was 4.439, 2.987, and 5.204 m²/g of bare ZnO, 3.0 % HA:ZnO, and 5.0 % HA:ZnO-NPs were 4.439, 2.987, and 5.204 m2/g, respectively. It is very likely that there are two different decay and/or capture mechanisms in the emission spectra because the TRPL decay profile behaves in a double-exponential way. The fast decay time constant (τ1) was 212 ps for bare ZnO and 3.0 % HA:ZnO NPs and 231 ps for 5.0 % HA:ZnO NPs. The slow decay time constant (τ2) has a similar pattern, with values of 3.716, 2.836, and 2.984 ns. The specific contact resistance values of the ZnO NPs increased from 0.113 to 45.624 ( × 105 Ω cm2) as a function of the HA concentration, as evidenced by the results of the electrical studies. The outcomes of this research present comprehensive information on noble-modified ZnO-NP materials containing HA for direct applications in electronic materials and photocatalytic degradation of organic waste in water.

Rotating cylinder electrode in reactive CO2 capture: Identifying active C species via transport, VLE models and kinetics

AbstractThis article explores technical challenges and potential methodologies for understanding electrochemical Reactive CO Capture (RCC) mechanisms. RCC offers potential energy cost advantages by directly converting captured CO into fuels and chemicals, unlike traditional carbon capture and utilization (CCU) processes that require sequential capture, concentration, and compression. However, direct conversion of captured CO introduces complexity due to additional equilibrium buffer reactions, making it challenging to identify active species for reduction in electrochemical studies. This article discusses methods to integrate transport, thermodynamics, and kinetics concepts to identify active carbon sources in RCC. Vapor‐Liquid Equilibrium (VLE) and transport models are validated against experimental results obtained in a gastight rotating cylinder electrode reactor and are shown as useful tools for studying RCC in heterogeneous electrocatalysts across different capture agents, solvents, and temperatures. This article establishes an experimental framework for advancing research in electrochemical RCC.

CO2 capture performance, kinetic and corrosion characteristics study of CO2 capture by blended amine aqueous solutions based on 1-(2-hydroxyethyl) piperidine

The chemical absorption method using amine-based aqueous solutions as absorbents is considered a critical technology in the mitigation of CO2 emissions. However, the trade-off between absorption performance and energy consumption presents a significant challenge for large-scale industrial applications. In this study, we propose using N-(2-hydroxyethyl)ethylenediamine (AEEA), 1-(2-amino Ethyl)piperazine (AEP) and piperazine (PZ) to regulate the CO2 capture characteristics of 1-(2-hydroxyethyl)piperidine (HEP) aqueous solution. We found that the addition of promoter AEEA/AEP/PZ increases the CO2 absorption and desorption performance of HEP aqueous solution. We established the CO2 capture mechanism, which involves the generation of HEPH+, carbamate, and bicarbonate during the absorption of CO2. During the desorption process, the bicarbonate can be decomposed, while the carbamate remains in the solution. Furthermore, we obtained data on the kinetics and corrosion characteristics of the blended absorbents. The absorption resistance of the three blended amine aqueous solutions is concentrated on the gas film, accounting for approximately 77 %. The corrosion rate of blended amine-enriched solutions on 20# carbon steel decreases with the increasing mass fraction of promoters or CO2 loading. SEM-EDS analysis revealed the presence of a dense FeCO3 oxide film on the surface of 20# carbon steel, which protects the carbon steel sheet from further corrosion. Overall, the proposed absorbents indicated a promising potential in the CO2 capture applications.

CubeSats for space debris removal from LEO: Prototype design of a robotic arm-based deorbiter CubeSat

Space debris has become a growing problem, and various studies indicate that the population of space objects has reached a critical density in low Earth orbits (LEO). Therefore, removing debris from the LEO is key to stabilizing the growth of space objects and making some of the orbits reusable for future launches. Deorbiting larger debris objects using miniaturized satellites, CubeSats is both economically viable and requires relatively less time for design & deployment. In this paper, we present a system-level study of orbital debris removal from LEO using CubeSats, detailing various existing debris tracking, rendezvous, capture, and deorbit mechanisms. A deep learning-based object detection algorithm has been utilized to improve the accuracy of detecting and localizing debris. We also present a discussion on the CubeSat-compatible capture & deorbit mechanisms identified from our study and an upper bound on the debris mass that can be deorbited from a given LEO orbit using CubeSats. We aim to demonstrate a case study for the orbital decay analysis of a CubeSat deorbiting the XSat, a microsatellite launched by Singapore. We detail the design of a 27U CubeSat deorbiter prototype equipped with a pair of robotic arms to capture the XSat. This analysis considers active deorbiting using Hall-effect thrusters, for which the required delta-V & propellant mass have also been computed.

Reversible Capture Mechanism of CO2 as a Zn(II)-Methylcarbonate.

In this study, we elucidate the reaction mechanism for capturing CO2 with the ZnL1(MeOH) complex (L1=diacetyl-2-(4-methyl-3-thiosemicarbazone)-3-(2-hydrazinatopyridine)) in a methanol solution, using density functional theory calculations. One pathway involves the protonation of ZnL1(MeOH) by methylcarbonic acid, followed by ligand exchange of MeOH with MeOCO2 -. An alternative mechanism suggests a tautomerization between ZnL1(MeOH) and Zn(HL1)(OMe), followed by CO2 insertion. The latter pathway is energetically more favorable than the former and more complex than initially proposed. In fact, we unveiled that the solvent catalyzes tautomerization, as one explicit methanol molecule acts as a proton transfer agent. Then, Zn(HL1)(OMe) captures CO2, yielding a methylcarbonate bound to the metal center. The final step involves a rearrangement that leads to the cleavage of the Zn-O(Me)(COO) bond and the formation of a new Zn-O(COOMe) bond, along with the rotation of the methylcarbonate group. We consider an additional mechanism that combines tautomerization and ligand exchange but is endergonic and requires a high activation barrier for the ligand exchange. Furthermore, we evaluate the ligand basicity through the pKa calculated values of the Zn(II) complexes, the effects of varying the ligand from 4-methyl-thiosemicarbazone to 4-ethyl (L2), 4-phenethyl (L3), and 4-benzyl (L4) derivatives, and reversibility of the reaction in an argon environment.

Atomic-level into the microscopic mechanism of gold capture by FeS during gold collection in matte process

Understanding the microscopic mechanisms involved in gold capture by FeS at the atomic level is crucial for optimizing the matte process and improving the gold recovery from gold concentrate containing arsenic and antimony. Herein, the DFT method was employed to explore the adsorption structure and electronic characteristics of a gold (Au) atom on the FeS surface. Furthermore, the effects of Fe/S vacancy and As/Sb dopant on Au adsorption were also investigated. The results reveal that the FeS(100) with S termination exhibits the smallest surface energy (0.56 J/m2) and possesses the highest stability amongst the low-index surfaces. Furthermore, the Au atom exhibits a preference for adsorption on the Fe-bridge site of FeS(100) through chemisorption due to the formation of a strong Au-Fe metallic bond, large adsorption energy (−5.40 eV), and small adsorption distance. Moreover, the presence of S vacancy enhances the Au capture capability of FeS(100) with an adsorption energy of −6.35 eV, while the Fe vacancy slightly weakens it. Additionally, the doping of As and Sb enhances the adsorption of Au atoms on FeS(100), and the Sb doping showcases a more distinct enhancement in Au capture efficiency. The findings of this work contribute to the advancement of matte processing technology, enabling enhanced gold recovery and potentially opening new avenues for the treatment of refractory gold ores.

Study on the mechanism of CO2 huff-n-puff enhanced oil recovery and storage in shale porous media considering heterogeneous structure

CO2 possesses several advantages, including strong solubility, effective viscosity reduction ability, and low miscible pressure, making it a promising candidate for enhanced oil recovery (EOR). Additionally, due to its adsorption capture mechanism, shale formations are considered ideal environments for CO2 storage. However, the influence of heterogeneity of shale multi-scale structure on CO2 migration mechanism, EOR, and storage mechanism is not clear. In this study, a heterogeneous shale structure model containing fractures and matrix was designed based on scanning electron microscope. The multiphase–multicomponent–multirelaxation model was used to study the fluid migration mechanism in the process of miscible CO2 huff-n-puff in shale reservoir. By analyzing density variations, velocity changes, and pressure distributions, the effects of diffusion coefficient, adsorption parameters, and fracture size were studied. Furthermore, by changing the matrix structure, the influence of heterogeneity on the law of oil and gas migration was explored. Additionally, a comparison between CO2 and water was performed. Finally, the influence of reservoir heterogeneity on fluid transport mechanism was studied. The results show that EOR and CO2 storage rate (CSR) are proportional to the diffusion coefficient. The main factor affecting the CSR is the adsorption capacity of rock to CO2. The larger CO2–oil contact area between the fracture and the matrix leads to a larger CSR, highlighting the importance of induced fractures. In addition, it was found that CO2 huff-n-puff was superior to water flooding, showing an EOR performance advantage of about 15%. This study is helpful for the practical application of CO2 huff-n-puff technology in the field of unconventional oil and gas development and CO2 storage.