This study investigates the application of supercritical carbon dioxide (scCO2) extraction for the effective removal of volatile organic compounds (VOCs) from recycled polypropylene (PP). The mass transfer characteristics of the process were quantitatively evaluated using the Sovová model. Extraction parameters including temperature, time, CO2 flow rate, and sample loading were varied, and a maximum VOC removal efficiency of 96.4% was achieved at 60 oC for 360 minutes. The Sovová model predictions showed strong agreement with the experimental data, with an absolute average relative deviation (AARD) of 4.61 to 10.8%, confirming the model’s reliability. Furthermore, the influence of the process parameters was analyzed by maintaining a constant solvent-to-feed (S/F) ratio while varying extraction times and sample masses in order to optimize the process and design scaled up models. These findings highlight the potential of scCO2 extraction for minimizing thermal degradation while achieving high-efficiency VOC removal. Furthermore, the findings suggest that scCO2 extraction may be practical for advanced plastic recycling technologies.

Ionic liquids (ILs) have received considerable attention in recent years due to their unique properties, including high solubility, extremely low vapor pressure, broad operational temperature ranges, and structurally tunable characteristics. Notably, certain ILs are capable of breaking azeotropes, thereby enabling the separation of azeotropic mixtures through distillation. In this study, we examine the effect of ILs on shifting the azeotrope of the {ethanol + benzene} using trihexyltetradecylphosphonium chloride ([P666,14][Cl]) and trihexyltetradecylphosphonium bis(2,2,4-trimethylpentyl)phosphinate ([P666,14][TMPP]). Isothermal vapor-liquid equilibrium (VLE) data for the ternary systems {ethanol + benzene + [P666,14][Cl]} and {ethanol + benzene + [P666,14][TMPP]} were measured at 313.15 K using headspace gas chromatography and correlated with the NRTL model. The ILs mole fraction was varied between 0.10 and 0.20. The results provide quantitative insight into the capability of phosphonium-based ILs to alter the azeotropic behavior of the ethanol–benzene system.

The exceptional properties of graphene, including its high strength, electrical conductivity, and flexibility, make it a promising material for a wide range of applications. However, its commercial adoption is hindered by challenges in the scalable production of high-quality graphene flakes. This study focuses on optimizing the liquid phase exfoliation (LPE) process, one of the primary techniques for producing graphene at a commercial scale. Among the various LPE processes, fluidic liquid phase exfoliation (FLPE) was employed due to its high-yield and productivity. By systematically investigating the effects of exfoliation time and graphite concentration in FLPE, it was found that an exfoliation time of 10 min maximizes the yield of few-layer graphene flakes. This finding challenges the conventional belief that longer exfoliation durations are more beneficial. In addition, it suggests that this more efficient production process can save both time and energy. Interestingly, the graphite concentration had minimal impact on exfoliation performance, achieving over 60% few-layer graphene flakes at a graphite concentration of 100 g L–1. This indicates that the process is robust across a range of concentrations so it can further simplify the production process. In addition, statistical analyses of cumulative distribution functions were performed to gain insights for making dimensional predictions about the exfoliated graphene flakes. While thickness changes could be predicted to some extent, lateral size changes remained somewhat unpredictable. This study underscores the critical role of exfoliation time in determining graphene quality, and provides valuable insights for the scalable production and improved performance of graphene-based applications.

Silicon is promising anode materials for lithium-ion batteries owing to its brilliant capacity (3,579 mAh g–1) and low operating voltage (< 0.2 V), however, the drastic volume expansion more than 300% caused inferior stability and drastic capacity fading. Herein, Silicon oxycarbide (SiOC) has been coated on the porous silicon (PSi) surface using silicone oil and sintering process to diminish volume expansion and enhance cycle stability of anode. SiOC shows the improved mechanical strength owing to ceramic properties, which accommodate the volume expansion during discharging and charging. Furthermore, the PSi and SiOC composite showed 1,587 mAh g–1 at 40 cycles

Efficient sorting of plastic waste is essential for enhancing recycling rates and reducing environmental impacts. Conventional sorting systems depend on fixed-capacity machines. However, when there are fluctuations in feed volume, these machines can be inefficient and require excessive investment. To address these issues, this study develops an optimization model for a single-stage plastic sorting process with variable-capacity machines using mixed-integer linear programming (MIP). The model allows machine capacities between 100 and 1,000 kg/h to be selected in increments of 100 kg/h at each sorting spot to allow for flexible adaptation to feed variations. Seven serially connected sorting spots were modeled to separate resins, with unsorted residues transferred sequentially to maintain mass balance. The objective function was formulated to maximize daily profit by balancing revenues from recovered plastics with investment and operating costs, including the energy consumption proportional to machine capacity. The results showed that the variable-capacity configuration significantly reduces the investment costs compared to fixed-capacity systems. The variable-capacity configuration also maintains or enhances the throughput and profitability, achieving a net profit of 4,969 US$/day. These findings demonstrate that flexible capacity planning can improve both the economic and operational efficiency of plastic waste sorting facilities, and can offer a practical approach for sustainable resource management.

This study aimed to design and optimize a vacuum distillation process for the efficient recovery of high-purity N-methyl-2-pyrrolidone (NMP) from waste mixtures generated during lithium-ion battery manufacturing. The process conditions were optimized using Response Surface Methodology (RSM) based on the Box-Behnken Design (BBD), with temperature (X1), time (X2), and fill volume (X3) selected as independent variables, and NMP recovery rate as the response. Analysis of variance (ANOVA) confirmed that the developed model was statistically significant (p < 0.0001) with a high coefficient of determination (R2 = 0.9795). The 3D response surface and contour plots revealed that both temperature and distillation time were major factors influencing recovery efficiency. The optimal conditions were determined to be 83 oC, 30 min, and 21.5% fill volume, yielding a predicted recovery rate of 92.72%. Experimental validation under the same conditions showed an average recovery of 91.8%, within 5% error of the predicted value, verifying the model’s reliability. HPLC chromatograms confirmed that the recovered NMP exhibited equivalent purity to standard NMP. These results demonstrate that the optimized vacuum distillation process provides an energy-efficient and environmentally friendly approach for solvent recycling, contributing to resource circulation and sustainable secondary battery manufacturing.

This study presents a techno-economic analysis of turquoise hydrogen production via methane pyrolysis using two different configurations: a plasma-only process and an integrated plasma-catalyst system. Material and energy balances were established based on laboratory-scale experiments and subsequently scaled up to a commercial hydrogen production capacity of 0.12 kg s–1. The levelized cost of hydrogen (LCOH) was calculated by considering the purchased equipment cost (PEC), operation and maintenance (O&M), fuel, electricity consumption, and carbon credit from solid carbon by-product sales costs. According to 2024 economic indicators (CEPCI = 798.8, electricity 85 $ MWh–1, natural gas 45 $ MWh–1), the plasma process showed an LCOH of 12.97 $ kg-H2 –1, while the integrated process achieved a lower LCOH of 9.95 $ kg-H2 –1, corresponding to a reduction of approximately 23%. The improved economics of the integrated process originated from the reduced electricity consumption, which outweighed the modest increases in PEC and O&M costs. In contrast, the small-scale integrated system (1.16 e–4 kg s–1) resulted in an excessively high LCOH of 57.35 $ kg-H2 –1 due to disproportionally high PEC and O&M contributions, highlighting the significance of plant scale processing for cost competitiveness. Sensitivity analysis revealed that electricity price is the dominant factor affecting LCOH, especially for the plasma-only process, whereas the integrated system demonstrated lower sensitivity. These findings suggest that integration of catalytic conversion with plasma pyrolysis can enhance its economic feasibility, particularly with reduced electricity costs and large-scale operations. Furthermore, the findings suggest that commercialization efforts should focus on securing low-cost electricity sources and valorizing solid carbon co-products.

In this study, a Co/ c-Al2O3 catalyst was synthesized and applied to the complete oxidation reaction of methane in order to thoroughly decompose low-concentrations of methane. A c-Al2O3 catalyst support was synthesized using a precipitation method with an NH₄OH aqueous solution. The concentration of the NH₄OH aqueous solution was varied from 1.0 M to 2.5 M in 0.5 M increments in order to investigate the effect of NH4OH concentration on the pore characteristics of the synthesized support. Using the synthesized c-Al2O3, a 5 wt% Co/ c-Al2O3 catalyst was synthesized via the wet impregnation method. The catalyst activity was measured for the methane oxidation reaction over the temperature range of 200 to 550 oC. The results confirmed that all catalysts exhibited a CH4 conversion rate exceeding 90% at temperatures above 500 oC. At a temperature of 400 oC, the catalyst using the support synthesized with 1.5 M NH4OH aqueous solution showed the highest CH4 conversion rate, followed by those synthesized with 2.5 M, 2.0 M, 1.0 M solutions.

Flash point (FP) is defined as the lowest temperature at which a volatile and flammable substance generates sufficient vapor to form an ignitable mixture with air. It represents the temperature at which the vapor above a liquid or solid can be transiently ignited upon exposure to an external ignition source, such as a spark, a flame, or heat. Reliable FP data are essential for the assessment and prevention of fire and explosion hazards. However, such data for certain binary mixtures remain limited in the literature. In this study, experimental FP data at 101.3 kPa were obtained for the miscible binary systems {methylcyclohexane (MCH) + ethylbenzene}, {MCH + o-xylene}, {MCH + m-xylene}, and {MCH + p-xylene}. The FP measurements of the binary systems were obtained using a Stanhope-Seta closed-cup flash point tester compliant with ASTM D3278. The experimentally determined FPswere compared with the values predicted by Raoult’s law and by excess Gibbs energy (GE) models, namely the Wilson, NRTL, and UNIQUAC equations.

With the rapid increase in plastic production, the generation of plastic waste has risen. Conventional disposal methods, such as landfills and incineration, have negative environmental impacts due to the emission of pollutants. Therefore, it is important to seek an environmentally neutral method for plastic waste disposal. As an effort to achieve this, this work proposes a pyrolysis-based process for plastic waste treatment that simultaneously enables sustainable hydrogen production. In the proposed process, waste PET is converted into pyrolysis gas, oil, and char through CO2-assisted pyrolysis. The carbon monoxide contained in the pyrolysis gas is utilized for hydrogen production via the water-gas shift (WGS) reaction. Two integrated configurations were investigated: (1) thermal energy recovery from byproduct combustion to generate steam, and (2) electricity generation through a steam Rankine cycle. The annual hydrogen production reached approximately 248 tons yr–1. A techno-economic assessment revealed that integrating steam recovery leads to a 42% lower levelized cost of hydrogen compared to the electricity generation system. Furthermore, the proposed process utilizes the CO2 generated within the process itself. Moreover, dependence on external energy was effectively reduced by integrating an energy recovery system. These findings suggest that the proposed process is a promising approach for simultaneously treating waste PET and achieving value-added hydrogen production.