In this study, a computational simulation was performed at varying operating pressures in order to achieve an acetal content of less than 10 ppm in a distillation column containing a mixture of ethanol and 2,000 ppm acetal. Ethanol and acetal form an azeotropic mixture at regions where there is a higher concentration of ethanol. The normal boiling point of ethanol is 78.29 oC, while that of acetal is 104.20 oC. However, in regions where the composition of ethanol is very high, an inversion of relative volatility occurs due to the azeotrope between the two components. Therefore, the conventional distillation process results in an azeotropic composition of the two components at the top of the column and almost pure ethanol at the bottom. The azeotropic composition between the two components makes separation through distillation easier as the pressure decreases because lower pressures cause the ethanol composition to shift towards the lower side of the mixture. Consequently, the separation efficiency was examined according to distillation column operating pressures.

Various liquid-phase exfoliation techniques have been researched for the mass production of graphene. As a result, significant progress has been made in using mass produced graphene for printed electronics. Liquid-phase exfoliation requires selecting suitable solvents and additives in order to enhance the graphene yield. However, these solvents are mainly organic and the additives are often incompatible with graphene ink formulation. Consequently, these solvents must be removed and replaced with solvents more suitable for the printing process, but doing so complicates ink formulation and increases the environmental harm of the process. To address this issue, this study produced graphene using solvents and additives that are compatible with the ink formulation process and optimized the production process to enhance the graphene yield and productivity. As a result, high-quality graphene ink with high productivity was obtained compared to the typical graphene production methods by removing the need for an additional ink formulation step. Furthermore, the ink demonstrated suitable physical properties for inkjet printing because it consistently formed stable droplets despite its high concentration. Additionally, printed graphene patterns with high resolution were fabricated. They displayed high electrical conductivity with a low number of print passes. These results indicate that this study’s graphene ink offers potential for the mass production of high-quality conductive graphene patterns for printed electronics.

Oxalic acid can be converted into glycolic acid through an electrochemical reduction reaction. Among the various materials studied for this purpose, TiO2 nanotube (TNT) electrodes are advantageous due to their eco-friendly properties and tubular structure, which facilitates a continuous two-electron reduction reaction and leads to a high selectivity for glycolic acid. However, the conversion rate of oxalic acid remains at only 40 ~ 50%. This study aimed to enhance the electrochemical properties of TNT by treating it with various metals to improve the conversion rate of oxalic acid. Compared to the conventional TNT used for the electrochemical conversion of oxalic acid, the metal-treated TNT showed significant differences in structure, conversion rates, and faradaic efficiency depending on the type of metal used. When Pt and Co were treated onto TNT, only the water reduction reaction occurred, and there was no reduction of oxalic acid. On the other hand, when W and Zn were treated onto TNT, the conversion rate of oxalic acid improved compared to the untreated TNT. However, the faradaic efficiency was slightly lower than that of the untreated TNT. This resulted from an increase in both oxalic acid and water reduction efficiencies due to the enhanced electrical conductivity of the TNT electrode caused by the doped ions. In the case of Cr-treated TNT, the nanotube structure was not formed and a non-porous electrode was formed. This led to a significant reduction in the surface area and a sharp decline in the conversion rate of oxalic acid.

Recently, there has been significant progress in pyrolysis research and development for waste tires. Pyrolyzing waste tires can yield 60% oil, 30% residue, and 10% gas. Waste tire oil contains approximately 1 wt.% sulfur due to the vulcanizing agent in the tires. Removing sulfur from the pyrolytic oil requires a hydrodesulfurization process, but this is not economically feasible because hydrogen and a catalyst must be used at a high temperature and pressure. This study verified the performance ameliorating effect of asphalt binder using waste tire pyrolysis by-products (oil and char). The effect of the asphalt binder was analyzed through general physical properties (penetration, softening point, ductility, flash point). Furthermore, the compatibility rating was measured using the process pressure aging vessel test and bending beam rheometer test. It was found that mixing char with the asphalt binder caused the penetration to be out of specification and become unusable. The baseline value was satisfied when the softening temperature was decreased while using oil and a flash point above 260 oC. The penetration tendency increased as the pyrolytic oil consumption increased. As the proportion of pyrolytic oil increases, the fatigue crack resistance and creep stiffness decrease, and the m-value increases. The modified asphalt binder blended with pyrolytic oil at 5 wt.% satisfied both the physical properties and the public utility rating criteria.

In this study, the properties of the pyrolysis products of plastics, primarily consisting of sorted high crystalline polypropylene (HCPP) in automobile shredder residue (ASR), at reaction temperatures ranging from 380 to 530 oC were investigated. The pyrolysis was conducted using a twin auger pyrolysis system and the yield and properties of the pyrolysis oil were observed as the reaction temperature changed. The optimal yield of pyrolysis oil was 38 wt% at a reaction temperature of 428 oC. According to the results of the GC-MS analysis, the concentration of aromatic compounds in the pyrolysis oil increased as the reaction temperature increased. The primary compounds were benzene, xylene, and toluene, and oxygen and nitrogen compounds were detected in significant amounts. Based on the results of the GC-MS analysis, the hydrocarbons were sorted by carbon number in order to analyze the naphtha content. The pyrolysis gas and char were analyzed by using GC-TCD/FID and ICP-OES instruments, respectively. The concentration of propene gas was the highest, and as the temperature increased, more methane gas was produced. In the case of the char, alkaline earth metals such as calcium and magnesium, as well asi ron, were detected, and the effects of these metals on the pyrolysis oil yield were investigated.

Recently, various efforts are being made to develop carbon dioxide capture, utilization and storage (CCUS) technology to reuse carbon dioxide as a useful resource. Carbonation is attracting attention as a technology that can fix and store CO2 in a thermodynamically stable state, and the product can be used as a high-value industrial material. In this study, the carbon dioxide capture characteristics of municipal solid waste incineration fly ash were investigated using a laboratory-scale carbon dioxide capture reactor. First, the change in pH of the reaction solution according to the dissolution of Ca in the fly ash sample was investigated. In addition, the main reaction mechanism was confirmed through thermogravimetric analysis of the fly ash sample before and after the reaction. The net carbon dioxide capture amount was determined using the reactive CaO content of the sample. The carbon dioxide capture capacity and efficiency were found to be 137 g/kg and 96.8%, respectively. In addition, the carbon dioxide capture products were able to meet environmental standards for recycling by mitigating heavy metal leaching. Through this study, the applicability of the municipal solid waste incineration fly ash to carbon dioxide capture process was confirmed. The results of this study can be used as basic data for upcycling processes such as making construction materials via carbon dioxide capture products.

A water-lean biphasic absorbent was used in order to reduce the energy required for absorbent regeneration in the conventional aqueous amine-based CO2 capture process. Secondary amines, EAE (2-(ethylamino) ethanol) and BAE (2-(butylamino) ethanol), were used as the main absorbents, and seven ether-based organic solvents with different logP were tested as phase-separation inducers. An absorbent that exists as a single phase before CO2 absorption but undergoes liquid-liquid phase separation after CO2 absorption was selected because its high CO2 absorption performance and viscosity were suitable for practical application. The absorbent composed of EAE/DEGDEE (diethylene glycol diethyl ether)/water was evaluated for its CO2 absorption performance based on the concentration of the organic solvent. For the 5 M EAE/20 wt% DEGDEE/water absorbent, the cyclic CO2 absorption capacity was 110 gCO2/Lsolvent, which was 1.8 times more than the cyclic absorption capacity of the conventional MEA (monoethanolamine) aqueous solution. This can be attributed to the CO2 enrichment effect that results from phase separation due to the low solubility of carbamate in the organic solvent as well as the reduced stability of the carbamate formed after CO2 absorption. 13C NMR analyses revealed that the CO2-lean phase primarily contained organic solvents, while the CO2-rich phase consisted of active amine, EAE carbamate, and protonated EAE.

In this study, catalytic decomposition of HFC-134, a fluorinated greenhouse gas contributing to global warming, was performed using a c-Al2O3-based catalyst with air as the oxidant and steam as the proton donor. An initial screening of the commercial c-Al2O3 showed that c-Al2O3(A) had the largest BET surface area and the highest amount of acid sites. In addition, it had the highest conversion rate at all temperatures. Although the activity of the catalyst may be slightly reduced, 5 wt% Mg/c-Al2O3(A) impregnated with Mg, which is known to inhibit the deactivation of the catalyst, was prepared and the HFC-134a conversion rate was measured at different temperatures to understand the effect of Mg impregnation on the HFC-134a conversion rate. It was found that the conversion rate decreased with Mg/c-Al2O3(A) compared to c-Al2O3(A). This was attributed to the decreased activity of Mg/c-Al2O3 due to the decreased BET surface area and acidity. On the other hand, Mg/c-Al2O3(A) showed a conversion rate close to 100% at 600 oC, similar to that of c-Al2O3(A). After optimizing GHSV at 600 oC, a long-term decomposition reaction of HFC-134a was carried out under GHSV = 2,000 h–1, and the amount of steam was reduced to a ratio of H/F = 2 to decompose HFC-134a with a conversion rate of 98% for 100 h. Through the catalyst analysis before and after the reaction, it was confirmed that the Mg/c-Al2O3(A) catalyst could decompose HFC-134a over a long time due to the reduction of AlF3 generation by Mg impregnation and steam injection.

In denitrification systems that use the selective catalytic reduction method, the flow rate of the ammonia injection nozzles is controlled by measuring the molar composition ratio of ammonia and nitrogen oxides at the inlet of the catalyst layer. In this study, the effect of the number of data measuring points on the optimization of the molar ratio for the reduction process inside the catalytic layers was analyzed by computational analysis. The working fluid is composed of air, ammonia and nitric oxide. The flow is assumed to be incompressible. The flow fields were solved using the k – e turbulence model in a commercial software named ANSYS-Fluent, which is widely used in thermal flow field analysis. Based on the experimental design, DesignXplorer was used to optimize the NH3/NO molar ratio. Two types of inflow gases were selected, upward skewed inlet flow and double parabolic inlet flow. The root mean square of the NH3/NO molar ratio at the inlet of the catalyst layer was chosen as the optimization parameter. According to the numerical analysis results, when the number of measuring points increased, the value of the parameter decreased and converged to a finite value when there were about ten (10) measuring points. The effect of improving the performance by controlling the injection of ammonia was 80.7% in the case of upward skewed inlet flow and 77.5% in the case of double parabolic inlet flow.

South Korea has the highest nutrient balance among the OECD countries, and its nutrient input from livestock excretion is continuing to steadily increase. In order to achieve sustainable agriculture, South Korea urgently requires the implementation of numerous comprehensive measures, such as improved fertilization management, advancements in livestock wastewater treatment technologies, and the revision of related regulations. This study examines the generation, treatment status, and methods of livestock excretion management over the past decade (2012 ~ 2022), following the ban on marine disposal. Additionally, it reviews domestic and international policies regarding livestock excretion and proposes policy recommendations. The findings indicate that a rising density of livestock per farm has led to increased excretion production, and that composting and liquid fertilizer treatment play an increasingly significant role. In the EU, nutrient management and regulation are integrated into agricultural policies and guidelines, and there is a growing emphasis on expanding biogas production using renewable resources. The insights gained from livestock excretion policies and biogas industry trends in this study are expected to inform the development of domestic policies to address the projected increase in livestock excretion treatment demands.