Korean Journal of Chemical Engineering最新文献

Pyroprocessing is a promising technology for recycling spent nuclear fuel by recovering actinides and reducing radioactive waste. Electrolytic reduction, a key step in pyroprocessing, converts oxide fuels into metals in a molten LiCl–Li₂O electrolyte. This study presents a thermodynamic analysis of actinide oxides to construct potential–oxoacidity diagrams as functions of electrochemical potential and oxide ion activity. Gibbs free energy data were used to analyze reduction pathways for uranium, plutonium, neptunium, americium, and curium. Results show that oxide ion activity significantly influences reduction potential, and actinides exhibit distinct reduction paths. Intermediate oxychloride formation is thermodynamically favored for americium and curium. Estimated cathodic potentials for complete metal formation range from − 3.23 V to − 3.37 V. Although reaction kinetics are not considered, the diagrams offer valuable insight into phase stability and feasible process conditions. This thermodynamic approach provides a useful guideline for optimizing electrolytic reduction conditions and supports future experimental and kinetic investigations.

Cigarette butts (CBs) have emerged as a significant environmental concern due to their widespread pollution, their removal, however, is a challenging task that requires substantial time and manpower, as they are often scattered across various locations, including landsides and seashores. Globally, trillions of cigarette butts are generated annually through smoking. The majority of these butts are disposed of via burning or land-filling, which places a heavy toll on both the environment and human health. In light of these issues, this review aims to comprehensively examine the toxicity of waste cigarette butts and explore eco-innovative solutions to tackle the CBs litter problem. Toxicity studies have revealed that the chemicals present in smoked CBs not only pose a severe threat to the environment but also carry the risk of physical contamination through the micro- and nanoparticles formed during material combustion. Moreover, a series of technological approaches have been proposed to uncover the hidden value in used CBs. These include propositions to incorporate this residue into high-volume production items or even directly recycle them. The utilization of recycled cigarette butts offers a two-fold benefit: it alleviates environmental and social concerns by reducing waste and provides a long-lasting solution. This review also emphasizes the necessity for continuous research and development in this area. Specifically, efforts should be made to enhance the performance and scalability of CB-derived nanofiber membranes for more in-depth applications in filtration systems. By synthesizing existing literature and suggesting future research directions, this review aspires to contribute to the advancement of sustainable and efficient filtration technologies.

Due to its high solubility and potential harm to metals, the speciation, electrochemical behavior, and removal mechanisms of selenium in the electrowinning nickel system have garnered significant attention for the production of high-purity nickel. The speciation of selenium in the electrolyte and nickel deposits was analyzed using high-performance liquid chromatography-mass spectrometry and X-ray photoelectron spectroscopy, respectively. The electrochemical behavior of selenium was investigated using cyclic voltammetry and chronoamperometry in the electrolyte. The selenium removal process was optimized, and the underlying mechanism of selenium removal was elucidated through a combination of inductively coupled plasma atomic emission spectrometry, X-ray diffraction, and scanning electron microscopy. The chromatogram results indicate that the primary speciation of selenium in the electrolyte is Se(VI). Selenium does not affect the nucleation and growth mechanism of nickel but leads to cathodic polarization. The occurrence states of selenium in the nickel deposits are NiSe, NiSe₂, Ni₃Se₂, and SeO₂. Furthermore, selenium removal experiments demonstrated that in nickel sulfate solutions containing 20 mg/L of Se(IV)/Se(VI), under conditions of 25 °C and pH 2 with 1000 mg/L NaBH₄, the removal efficiency reached 98.77% for tetravalent selenium (Se(IV)) and 83.60% for hexavalent selenium (Se(VI)). During the chemical reduction process, soluble selenium was initially reduced to elemental selenium, which subsequently reacted with nickel to form NiSe and Ni₃Se₂. This study provides valuable guidance for the removal of selenium from highly acidic solutions.

Photocatalysis offers a sustainable approach to degrade toxic organic pollutants from wastewater. Zinc oxide (ZnO) thin films exhibit strong potential for high-performance photocatalytic applications; however, their wide band gap and rapid electron–hole recombination significantly limit their efficiency. This limitation can be mitigated by incorporating metal dopants during the photolysis decomposition process, which effectively narrows the band gap and suppresses charge carrier recombination, thereby enhancing the overall photocatalytic activity. Here, we report the fabrication of copper (Cu) and manganese (Mn) co-doped ZnO layers through a facile and efficient spin-coating method, to enhance the catalytic efficiency of synthetic pigments. The doping atoms (Cu + Mn) were successfully incorporated into ZnO thin films without destroying the ZnO crystal structures. The incorporation of dopant atoms into ZnO thin films reduced the band gap and introduced intermediate energy levels, facilitating efficient charge separation and suppressing electron–hole recombination. Under visible light irradiation, the (1% Cu + 8% Mn)-doped ZnO thin film exhibited superior photocatalytic activity, attributed to the strong surface plasmon resonance of the dopant atoms and the improved charge carrier transport within the film’s nanostructures. Photocatalytic degradation tests performed on organic dyes, including methyl orange, malachite green, methylene blue and congo red demonstrated degradation efficiencies exceeding 94% within 120 min. This study offers an eco-friendly and innovative viewpoint for developing visible-light-responsive (Cu, Mn): ZnO-based photocatalysts, which are projected to be utilized for the remediation of environmental contaminants and can be reused multiple times without a degradation in efficiency.

Solid oxide fuel cell (SOFC) electrolytes has advanced from conventional oxide-ion conductors such as YSZ to sophisticated proton-conducting and co-ionic systems. This review synthesises progress across oxide-, proton- and dual-ion-conducting families within a harmonised 500–800 °C window, using mainly a single cell-level reporting schema. By centring the comparison at the cell level, we assemble state-of-the-art demonstrations and map them onto a durability framework that makes performance limits and degradation risks explicit. Tables 7 and 8 convert materials insights into stack-relevant guidance, enabling like-for-like benchmarking that is reproducible and decision-oriented. Three messages emerge where oxide-ion systems are the most mature and stack-ready, yet ≤ 650 °C operation is constrained by residual ohmic losses and cathode surface-exchange kinetics, even with sub-micrometre membranes. Protonic cells deliver high conductivity and competitive power at 500–650 °C but require chemical robustness against CO₂/H₂O to stabilise Ba-containing perovskites. Dual-ion electrolytes spanning engineered semiconductor-ionic heterostructures and composite co-ionic designs achieve attractive outputs near 500–550 °C, although long-term stability is constrained by secondary-phase volatility, coarsening and interfacial drift. Architecture and processing are decisive levers: dense ultrathin electrolytes with targeted interlayers, bilayer/multilayer stacks, space-charge/strain-engineered heterostructures and thin-film routes complement scalable tape-casting, screen printing, extrusion and micro-tubular formats. We prioritise chemically robust protonics; stabilised co-ionic systems with engineered interfaces; cathode-electrolyte pairings qualified under realistic fuels and humidities; and standardised reporting that ties electrochemical diagnostics and post-mortem analysis to fade metrics. This framework provides decision-oriented evidence to guide device design, operating policy and scale-up from record single cells to stacks.

Accurate and efficient prediction of battery degradation is essential for optimizing energy storage system design and control. This study introduces a hybrid modeling framework that combines reduced-order modeling (ROM) insights with experimentally validated deep neural networks (DNNs) to predict degradation in lead–carbon (PbC) batteries. Using voltage–capacity profiles from 258 experimental charge/discharge cycles, we extract four physically meaningful input features—cycle number, capacity, charge voltage, and discharge voltage—to train a ROM-guided DNN surrogate. The model predicts two key health indicators: capacity retention (CapRet) and end-of-discharge voltage (EoDV). It generalizes well across five scenario types, including extrapolated conditions up to 700 cycles and varying voltage/capacity inputs. Predictions remain smooth and physically consistent, with validation yielding R² > 0.99 and low MSE. In terms of computational performance, the DNN achieves sub-second inference (~ 0.02 s), offering over five orders of magnitude speedup compared to full COMSOL simulations (~ 25 h), and ~ 1000× faster than ROM (~ 22 s). This enables rapid scenario testing and real-time diagnostics. The proposed framework provides a scalable and interpretable solution for battery performance forecasting, well-suited for deployment in digital twins, battery management systems, and advanced energy storage design workflows.

This study advances the synthesis of crosslinked dextran microspheres (CDMs) by addressing a critical gap in understanding real-time droplet evolution during inverse suspension crosslinking. Using optical and SEM microscopy, we characterize droplet progression through four distinct stages—transition, quasi-steady-state, growth, and identification—revealing the role of viscosity-dependent breakage-coalescence dynamics in size distribution changes. We further develop the first population balance model (PBM) integrated with genetic algorithm (GA) optimization to predict transient particle behavior. By incorporating a reaction-conversion parameter, X(t), our model links rheology to crosslinking kinetics, achieving high predictive accuracy (MSE < 5%). Experimental results demonstrate that increasing dextran concentration (12.5–50% w/v) elevates viscosity by > 3000%, suppressing droplet breakage and producing larger particles (27 → 188 µm) with broader distributions (Span 0.98 → 2.61). This work represents a significant improvement over previous statistical approaches, offering the first quantitative PBM-GA framework for connecting processing conditions to dynamic particle evolution. Our findings provide new insights into CDM formation kinetics and enable rational microsphere design for biomedical applications, bridging the gap between empirical observation and mechanistic control in dextran-based particle synthesis.

The development of Cs₂AgBiCl₆ perovskites has attracted considerable interest in photovoltaics and optoelectronics due to their low toxicity and good stability. However, the indirect nature of its bandgap leads to a low absorption coefficient, which remains a major limitation for solar cell applications. In this study, a series of 26 Cs₂AgInₓBi₁₋ₓCl₆ (x = 0, 0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875, and 1) models with tunable bandgaps are designed through In³⁺ doping of pristine Cs₂AgBiCl₆. The structural, electronic, and optical properties of the stable Cs₂AgInₓBi₁₋ₓCl₆ are systematically investigated using first-principles calculations to evaluate potential for photovoltaic and optoelectronic applications. The results demonstrate that the bandgap transitions successfully from indirect to direct with increasing In³⁺ concentration, yielding a series of perovskites with gradually varying bandgap. Among these, Cs₂AgInₓBi₁₋ₓCl₆ (x = 0.75) exhibits outstanding optical properties, including a high absorption coefficient, high dielectric constant, and low reflectivity. It is inferred that the distinctive band structure, characterized by a dispersive conduction band (CB), contributes significantly to the enhanced optical performance. This work provides deeper insight into the intrinsic electronic properties of In³⁺-doped Cs₂AgBiCl₆ perovskites and establishes a foundation for improving the optical characteristics of In/Bi-based double perovskites. Furthermore, it offers systematic theoretical validation for previously reported experimental results.

We propose a universal surface reaction model that incorporates neutral and ion transport mechanisms through a steady-state passivation layer in high-aspect-ratio plasma oxide etching. This two-layer model effectively captures the concurrent deposition and etching characteristics by explicitly accounting for neutral diffusion and ion scattering transport processes. Detailed kinetic models for deposition and etching are developed to closely reflect the transport mechanisms in a steady-state passivation layer (SSPL), and their validity is supported by sensitivity analyses of key parameters against experimental data. Consequently, the proposed model provides a realistic description of plasma oxide etching behavior. Furthermore, by integrating this model with a well-established three-dimensional ballistic transport model in high-aspect-ratio (HAR) structures, we offer valuable insights into previously unexplored aspects of the HAR etching process.

One of the crucial problems in recovering precious metals from the zinc plant residue is the environmental effects and high energy consumption. Efficient and green solvents have a special place in the development of the recovery process for the critical ions. This paper presents the separation of Cd(II) ions from a hydrochloric acid solution, including zinc ions, achieved by applying of phosphonium ionic liquids (Cyphos IL 104). At first, the solvent extraction was examined experimentally in the batch tests, and it was observed that 0.1 M HCl was a relative acidic solution to reach the maximum separation factor. Afterwards, the effects of certain crucial factors, such as time, the concentration of Cyphos IL 104 as the extractant, and the temperature, were examined to achieve the highest possible separation factor. Based on batch studies, an optimal feedstock was prepared to investigate the real-scale conditions in the multistage contactor. The ionic liquid was found to extract Cd(II) more efficiently in the continuous operation mode. The mass transfer performance of the column showed that the proposed correlations were not successful in predicting the results. Therefore, a new equation for the overall aqueous phase mass transfer was proposed by utilizing the obtained results from the extraction of both ions with ionic liquid. Thus, the utilization of Cyphos IL 104 as an alternate solvent to replace traditional organic solvents is one of the promising approaches as well as a green method for separating Cd(II) ions from the real leaching solution of zinc plant residue.