Coking wastewater has long been a major source of environmental pollution. Supercritical water oxidation (SCWO) is an effective technology capable of degrading such wastewater deeply into carbon dioxide, water, and nitrogen. However, due to the complex composition of coking wastewater, kinetic data for the process are limited, as establishing accurate simulation models is challenging. To address this issue, an artificial neural network (ANN) based kinetic rate correlation was developed to characterize the reaction kinetics. This data-driven model was then integrated with Aspen Plus® to simulate the degradation behavior of typical oxygen-and nitrogen-containing compounds in coking wastewater, namely phenol, pyridine, and quinoline. Phenol was simulated first to obtain temperature profiles, species concentrations, and reaction rates along the reactor height under different inlet conditions. The model was subsequently validated with other nitrogen-containing compounds. The proposed SCWO simulation approach has potential for application to other oxygen- and nitrogen-rich wastewaters.
In solid–liquid mixing processes involving floating particles, the minimum impeller rotational speed for particle drawdown has been inconsistently defined, limiting its usefulness in process design and scale-up. In this study, the solid–liquid mass transfer coefficient, kL was measured using an electrical conductivity method based on ion exchange in a stirred tank over a wide range of volumetric power consumption, PV. Segmented regression analysis of the kL data revealed a distinct change point at which the rate of increase in kL with respect to PV decreased significantly. Independent observations of particle behavior indicated that this transition corresponds to the condition where no particles remain stationary at the liquid surface for more than 1–2 s, although some particles may still transiently appear at the surface. This result provides a practical criterion for particle drawdown, organized by PV, enabling scale-up and contributing to reliable operation and design of stirred vessels.
Supercritical carbon dioxide (SC–CO2) extraction has emerged as an environmentally friendly technique for recovering bioactive compounds from plant matrices. In this study, the extraction of oil and antioxidant compounds from Nicotiana tabacum was investigated using a co-solvent-assisted SC–CO2 process. The effects of pressure (20–30 MPa), temperature (40–60 °C), and ethanol co-solvent concentration (4–8%) on oil yield, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity (AA) were evaluated using a Box–Behnken design (BBD) combined with response surface methodology. The experimental results showed that oil yield ranged from 5.21 to 8.56%, while TPC, TFC, and AA varied between 33.72–95.43 mg/100 g, 29.54–79.21 mg/100 g, and 62.72–92.83%, respectively. Statistical analysis confirmed that the quadratic models were significant for all responses, with coefficients of determination (R2) between 0.8450 and 0.9915. Pressure was identified as the dominant factor influencing phenolic, flavonoid, and antioxidant recovery, whereas ethanol co-solvent concentration significantly enhanced oil yield through polarity modification of the supercritical solvent. Response surface analysis further demonstrated the synergistic effects of pressure and ethanol in improving extraction performance. Numerical optimization predicted the optimal extraction conditions at 20 MPa pressure, 47.8 °C temperature, and 5.96% ethanol, yielding 7.21% oil, 91.60 mg/g TPC, 77.33 mg/g TFC, and 81.88% antioxidant activity. The findings highlight the importance of co-solvent-assisted SC–CO2 extraction for enhancing the recovery of antioxidant-rich tobacco oil, providing a sustainable and efficient approach for valorizing tobacco-derived bioactive compounds.
Radiopharmaceuticals form the molecular basis of nuclear imaging and radionuclide therapy. As clinical demand continues to grow, systematic optimization of radiolabeling reactions is increasingly important for efficient and reliable radiopharmaceutical production. This perspective first summarizes key radiochemical performance metrics for radiolabeling optimization. Representative radiolabeling strategies involving nonmetal and metallic radionuclides are then discussed, together with their associated reaction variables and practical constraints. Building on this foundation, production-oriented commercial automated synthesis platforms are discussed to illustrate the device-level parameter optimization space, while rapid experimentation platforms are introduced as complementary tools for acquiring optimization data. Finally, inspired by recent advances in intelligent algorithms for chemical synthesis, this perspective discusses Bayesian optimization-centered strategies as decision-support tools for radiolabeling reaction optimization under expert guidance.
The development of cellulose nanofiber-reinforced plastics (CNFRPs) is a possible option for reducing the environmental impact of plastic products, such as automotive components. This study conducted a life cycle assessment (LCA) of CNF-reinforced bio-polyethylene (CNF-BioPE) as an alternative to conventional talc-reinforced polypropylene (Talc-PP). The CNF-BioPE was produced using the pulp direct kneading method, which simultaneously disintegrates pulp and disperses CNF into the polymer matrix, enabling industrial-scale feasibility. An LCA was conducted to compare the environmental performance of CNF-BioPE and Talc-PP. The study analyzed process inventories from raw material extraction to molding, including energy consumption during kneading and injection molding. The results indicated that scaling up CNF-BioPE production significantly reduces life cycle greenhouse gas (LC-GHG) emissions because of improved process efficiency and energy savings. While laboratory-scale production showed higher emissions than Talc-PP, industrial-scale production reduced emissions to nearly half of those for Talc-PP. Additionally, incorporating low-carbon electricity further reduced LC-GHG emissions by up to 43%. The study also examined the effects of land use change (LUC) associated with biomass cultivation, revealing that variations in LUC scenarios significantly influenced overall emissions. Furthermore, optimizing cooling time during injection molding resulted in energy reduction of 24% at the process level, with a reduction of 4% across the product life cycle. These findings suggest that CNF-BioPE has the potential to outperform Talc-PP in environmental performance when process improvements and renewable energy are applied. However, successful large-scale implementation requires advancements in acetylation process efficiency, stable demand for CNF-BioPE parts, and improvements in recycling infrastructure. Overcoming these challenges will be crucial for the widespread adoption of CNFRPs in the transition toward a decarbonized and resource-efficient society.
Establishing a low-cost, low-environmental-impact, and highly efficient method to separate lithium iron phosphate (LiFePO4, LFP) cathode active materials from the aluminum (Al) foil of spent LFP cathodes while preserving the crystal structure remains a challenge for direct regeneration of spent LFP cathodes. In this study, we proposed a separation method for the active material layer from Al foil by inducing interfacial hydrogen (H2) gas evolution during immersing spent LFP cathodes in ultrapure water. Regardless of the number of charge-discharge cycles or the solid-to-liquid ratio, complete separation was achieved within approximately 3 minutes even under mild stirring conditions, while the separation efficiency evaluated after 10 minutes exceeded 97%. Under optimized conditions, separation occurred within several tens of seconds. Analysis of the immersion solution suggested that lithium hexafluorophosphate (LiPF6), the electrolyte remaining in the spent cathode, partially hydrolyzed, generating acidic and fluorine-containing species. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) indicated that the double-layer passivation film formed on the Al foil of the spent cathode, consisting of Al2O3 and AlF3, was locally thinned and removed by the fluorine species, exposing metallic Al. Micro-galvanic couples between the exposed metallic Al and carbon black (CB) in the active material layer are considered to trigger interfacial H2 gas evolution, thereby inducing separation at the interface. The recovered active material layer was characterized by inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray diffraction (XRD), which confirmed that the lithium content and crystal structure were largely retained. This method shows promise as a rapid, highly efficient separation approach for the direct regeneration of spent LFP cathodes.
The excess dielectric constant was proposed as ( ln epsilon 0)E= ln epsilon-x1 ln epsilon 1-x2 ln epsilon 2. The value of -( ln epsilon 0)E was adopted with an equation similar to the Wilson activity coefficient model (Wilson-DIELECT model). The interaction energies were fitted with the reported dielectric constant data for benzene - toluene, bromobenzene - chlorobenzene at 293 K, bromobenzene - methanol and nitrobenzene - 1-propanol at 298 K, and methanol - water and ethanol -water at (293-333) K. The AARDs for epsilon 0 were obtained to be 0.29%, 0.47%, 2.51%, 0.95%, 0.20% and 0.50%, respectively. The evaluation was also carried out by using the reported dielectric constant data for ethanol - dimethyl ether, pressurize with 1.00 MPa at (293-313) K. The pressure and temperature dependences were assumed only in liquid molar volume for pure constituents, and the temperature dependence was set in the energy parameters in the Wilson-DIELECT model. The AARD was 0.81% for epsilon 0.
The wet powder behavior has frequently been studied using the discrete element method (DEM), which incorporates a liquid bridge force model. However, the implementation of the liquid bridge force model in DEM simulation remains ambiguous. To address this uncertainty, we systematically examined the impact of various implementation methods of liquid bridge force models on the DEM simulation results of wet powder behavior. In this study, we focused on the criteria for liquid bridge formation and contact force models including liquid bridge force. We evaluated their effects through drawdown and rotating drum tests. The choice of the contact force model including liquid bridge force significantly affected the simulated wet powder behavior, while the formation criterion had a negligible effect. Our results demonstrated that the differences in the treatment of tangential contact forces affected wet powder behavior under dynamic conditions. Moreover, DEM simulations using conventional liquid bridge force models, including capillary and viscous forces, failed to simulate the actual wet powder behavior. This is because of their inability to capture the reduction in tangential forces, highlighting the critical need for an improved contact force model that can adequately account for the reduction in tangential forces under wet conditions.
In this study, we employ overdamped Brownian dynamics simulations to investigate transient colloidal gels formed through Lennard-Jones attractions. Systems with volume fractions phi = 0.07-0.13 were examined to assess how concentration controls gel formation, structural connectivity, and mechanical response. It was found that gelation proceeded through a universal three-stage pathway-rapid cluster formation, slower restructuring, and network arrest-whose timescales and energy minima depended systematically on phi. Structural analysis via contact number and radial distribution functions revealed a transition from tenuous, fractal networks at low phi to dense, highly coordinated networks exhibiting frustration-limited packing at high phi. Steady shear measurements showed strong shear-thinning behavior for all systems and a monotonic increase in viscosity with phi, reflecting enhanced network connectivity and restricted relaxation pathways. Oscillatory shear tests further demonstrated that the gels were strongly elasticity-dominated (G'>> G"), with linear viscoelastic plateaus that extended and stiffened as phi increased, followed by characteristic softening and yielding at larger strains. Together, these results provide a mechanistic link between particle concentration, microstructure, and emergent rheology, demonstrating that Brownian dynamics simulations can reliably capture key features of transient colloidal gels and offer predictive insights into their macroscopic behavior.
Mathematical models that predict critical quality attributes (CQAs) of the final product play a significant role in quality assurance in the pharmaceutical industry. Models whose input variables include process parameters (PPs) associated with specific equipment require reconstruction when equipment configurations change. This study proposes a systematic method for selecting input variables in a continuous direct compression process with the aim of eliminating the need for model reconstruction when mixer configurations change. We conducted 19 experiments by varying nine PPs and measured five CQAs and 24 material attributes (MAs) of intermediate products at two mixing processes. Multiple statistical models were developed by incrementally adding mixer-independent PPs, MAs, and mixer-dependent PPs to input variables. Partial least squares regression provided high prediction accuracy for the disintegration time, dissolution rate, and tablet weight relative standard deviation (RSD), while Gaussian process regression was effective for the hardness and tablet acetaminophen mass fraction RSD. These high-performance predictions were achieved using only MAs and mixer-independent PPs. These results demonstrate the potential for constructing mixer-independent models and thereby avoiding the need for model reconstruction when mixer configurations change. This study contributes to facilitating flexible equipment configuration changes.
To realize flexible heat integration among several reactions, a bench-scale three-compartment circulating fluidized bed (CFB) system integrating internal J- and L-Type loop seals aimed at developing. This process requires the prediction of the particle transport rates from the operational parameters. This study aimed to develop a predictive model for particle transport rates (Gs) in the J-Type loop seal. Experiments were conducted in a specially designed two-compartment fluidized bed equipped with a J-Type loop seal on the partition wall, focusing on the relationship between Gs and loop seal aeration velocities. Two characteristic behaviors were observed in the dependence of Gs on the bed height difference (Delta h): a square-root increasing region at low Delta h and a linear increasing region at high Delta h, separated by a critical transition point (Gss). A mathematical model that incorporates both regions was developed based on loop seal aeration velocities. Furthermore, the fitting parameters in the model were obtained through linear regression analysis as a function of particle size, thereby enhancing the model's applicability across a range of operating conditions.
This study evaluates the performance, combustion, and emission characteristics of a Kirloskar TV1 compression ignition engine fueled with an 80% Hevea brasiliensis biodiesel and 20% n-Octanol blend (HB80OCT20) under hydrogen induction rates of 8, 10, 12, and 14 LPM. Hydrogen enrichment significantly influenced combustion phasing and energy utilization. The maximum brake thermal efficiency (BTE) of 32.33% was achieved at 14 LPM under full-load conditions, accompanied by the lowest brake specific energy consumption (9.752 MJ/kWh), indicating enhanced premixed combustion and rapid energy release. However, this condition also produced the highest peak cylinder pressure (88.72 bar), elevated heat release rate, increased NO & acirc;," formation, and noticeable engine vibration, suggesting operation near the upper combustion intensity threshold. Hydrocarbon (HC), carbon monoxide (CO), and smoke emissions were substantially reduced with hydrogen induction, with minimum HC, CO, and 39% smoke reduction observed at 8 LPM compared to diesel. Conversely, NO & acirc;," emissions increased with hydrogen flow rate due to intensified thermal loading associated with faster combustion kinetics. A multi-criteria composite score analysis incorporating efficiency, emissions, and combustion stability parameters identified 10 LPM (13.12% hydrogen energy share) as the optimal operating condition. At this rate, BTE improved by 4.4% over diesel while maintaining controlled NO & acirc;," levels and stable peak pressure (82.4 bar), providing the best overall performance-emission balance. The findings demonstrate that moderate hydrogen induction (10-12 LPM) optimizes flame propagation and carbon oxidation without inducing excessive combustion intensity, making it a technically viable and sustainable strategy for renewable dual-fuel diesel engine applications.
Mixed matrix membranes (MMMs) incorporating the metal-organic framework CALF-20 were developed for CO2 separation using Pebax (R) 2533 as the polymer matrix. CALF-20 prepared under concentrated synthesis conditions in a methanol-water mixed solvent was successfully dispersed into the polymer matrix with filler loadings of up to 90 wt% without mechanical brittleness. At moderate filler loadings, the MMMs exhibited significantly enhanced CO2 permeability and improved CO2/CH4 separation performance compared with pristine Pebax (R) 2533. Gas permeation analyses revealed that CO2 transport in the MMMs followed a dual-mode sorption behavior, indicating that the micropores of CALF-20 functioned as effective adsorption and diffusion pathways for CO2. The activation energy for CO2 permeation decreased upon CALF-20 incorporation, further supporting the contribution of the MOF micropores to gas transport. Performance prediction based on the Maxwell model suggested that CALF-20 possesses intrinsically high CO2 permeability and selectivity. At very high filler loadings, membrane selectivity deteriorated due to the formation of pinhole defects; however, these materials retained high CO2 adsorption capacity and fast adsorption kinetics. These results demonstrate that CALF-20-based MMMs are promising candidates for membrane-based CO2 separation, while also offering potential for adsorption-based CO2 capture applications.
Calcium chloride is a promising ammonia absorber for mild-condition separation processes; however, its strong hygroscopicity requires careful dehydration to avoid secondary reactions. In this study, we investigate the effect of dehydration pretreatment on the stability of ammonia absorption in calcium chloride. Dehydration at 220 degrees C for 1 h resulted in the generation of CaClOH and NH4Cl during subsequent NH3 absorption/desorption cycles, indicating incomplete removal of hydrates. In contrast, extended dehydration at 220 degrees C for 5 h effectively suppressed these by-products and enabled stable ammonia cycling. These results demonstrate that dehydration duration (e.g., 5 h at 220 degrees C), rather than temperature alone, critically determines the operational stability of calcium chloride ammonia absorbers.
A pH-responsive polymer coated gate membrane based on inorganic materials with excellent mechanical durability enables pH-dependent substance separation with promising applications in various biochemical and industrial processes. The membrane was fabricated by coating on a tubular alpha-alumina porous support 6 mm in diameter by graft polymerization with polyacrylic acid (PAA) that swells at high pH. The permeances of acetic acid, caffeine, phenol, and 2-butanone, which have different molecular sizes and negative charges, were evaluated in aqueous solution over a tenfold concentration range using a circulation system. The permeation rate remained almost constant regardless of concentration. The permeance of acetic acid, caffeine, and phenol decreased with increasing pH, and the permeance magnitude was in the order caffeine < acetic acid < phenol. The permeance of 2-butanone was the highest of the compounds and almost constant regardless of pH. At high pH, permeance was decreased by the electrical repulsion between the negative PAA chain and compound ions and by the decrease in pore size due to the swelling of the PAA caused by the electrical repulsion between the negative PAA chain charges. The reversible pH response performance of the membrane was confirmed by a pH swing experiment using phenol. These results demonstrate that the PAA-coated porous membrane functioned as a pH-responsive membrane. [GRAPHICS]
A life cycle assessment of various photovoltaic cells (PVs), which revealed that polycrystalline silicon PVs have great potential for CO2 reduction at the current development stage, was performed. The effect of PVs on CO2 reduction was calculated to be greater than that of forests. To estimate the global temperature, an N-layer atmospheric model was used, and the energy radiation and absorption by the atmosphere were calculated. An accurate estimation was achieved with 8 layers of the atmosphere. This model was applied to estimate the effect of the increase in temperature due to the accumulation of energy on the Earth by PVs, and the effect of PVs on global warming was determined to be negligible. A strong correlation between the CO2 concentration and temperature increase was confirmed. Thus, CO2 reduction via PV installation seems to be an appropriate strategy against global warming. A new method for establishing a PV installation strategy was proposed, and a case study was conducted in Kyoto city. The findings revealed that no deforestation was required to meet the estimated power demand but that only installation on the existing artificial structure could meet it.
Enzyme-catalyzed transesterification of triolein and methanol to produce methyl oleate (biodiesel) was studied using a free-form lipase from porcine pancreas. This study aims to produce biodiesel under mild conditions, making it environmentally friendly and cost-effective. Therefore, several factors, including the organic solvents, molar ratios of triolein to methanol, and pH, were investigated to find the optimal conditions favorable for producing methyl oleate (biodiesel) from triolein (a triglyceride) and methanol (a short-chain alcohol) in acetone in the reaction medium. In the course of experimentation, the addition of water and the utilization of surfactant decreased the reaction rate instead of enhancing the reaction system. Hence, this study suggested that the utilization of the existing minimum amount of water present in acetone is necessary for biodiesel production. The findings of this study suggested that acetone is a suitable main reaction medium for the enzyme-catalyzed transesterification reaction and can increase production from triolein to methyl oleate with a single addition of methanol. The biodiesel achieved was 47 mM in the form of methyl oleate obtained with 10 mg/mL lipase, 100 mM triolein, and 300 mM methanol in acetone at a neutral pH environment. The removal of surfactant and water is economically advantageous in terms of the cost of production. Thus, free lipase from the porcine pancreas is promising for biodiesel production in acetone using triolein and methanol.
In this study, the effects of rib configuration on flow structure and axial mass transport in Taylor-Couette flow were investigated using computational fluid dynamics. Two configurations were considered: ribs attached to the inner cylinder and to the outer cylinder, with an axial spacing equal to twice the gap width. Steady-state flow fields and transient tracer transport were simulated under laminar and wavy vortex flow regimes. The results reveal that the rotational direction of Taylor vortex pairs depends strongly on the rib configuration, leading to distinct intercell transport characteristics. Tracer-response analyses show that ribs significantly suppress axial dispersion compared with non-ribbed Taylor-Couette flow. Moreover, ribs attached to the outer cylinder are more effective than those on the inner cylinder in reducing axial dispersion and achieving plug-flow-like behavior. These findings offer practical design guidelines for Taylor-Couette flow reactors requiring controlled axial mass transport.
Chemical plants are transforming from safe and stable to high-efficiency and decarbonized production. Efficient utilization and recovery of saturated steam, one of the major energy sources, are essential. However, in medium and large chemical plants with hundreds of steam-related facilities, the number of flow meters is limited, making it difficult to measure heat balance directly. Moreover, identifying the types of process disturbances that cause heat loss in real time remains challenging for less-experienced operators. This study proposes a method to define and visualize real-time heat balance indicators (heat input, heat output, heat loss, work) as heat key performance indicators (KPIs) by using existing process control data and to formulate disturbance KPIs that represent process disturbances based on engineering knowledge. The proposed methods were applied to a vinyl acetate monomer (VAM) process constructed using a dynamic process simulator. The results confirmed that the approach reduced the need for new sensors and assisted in identifying the causes of heat loss, as well as estimating unmeasured heat KPIs.
Effective wetting area between the gas and the absorbent can enhance the efficiency of gas absorption. In this study, new gas absorption equipment packed with a flat glass fiber filter was developed, and the prevention of liquid stagnation due to gravity and liquid channeling in the glass fiber filter was demonstrated. As a result, the effective wetting area of this equipment was measured to be between 50,000 and 110,000 m2 & centerdot;m-3 when the flow rate of gas was controlled between 0.015 and 0.063 m3 & centerdot;(m3-filter unit)-1 & centerdot;s-1 and flow rate of liquid was controlled between 0.78 & times;10-4 and 3.1 & times;10-4 m3 & centerdot;(m3-filter unit)-1 & centerdot;s-1, respectively. To evaluate the effect of a large effective wetting area on gas absorption performance, we selected two topical systems: 100% of carbon dioxide (CO2) absorption into potassium hydroxide aqueous solution for CO2 utilization in agriculture and NOx elimination from exhaust gas derived from power plants. When the packing height of this equipment was 0.825 m, 99.7% removal efficiency of carbon dioxide (with 12 vol% of inlet concentration) was achieved, and the concentration of CO2 (0.03 vol%) at the outlet was less than the concentration in the atmosphere (about 0.04 vol%). However, the removal efficiency of nitrogen dioxide was not so high (64-78%). This was because the nitrous acid produced by the absorption of nitrogen dioxide into water would contribute to the desorption of nitrogen monoxide.
