• Korean Journal of Chemical Engineering
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• v.35 no.11
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• pp.2191-2197
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• 2018

To remove tar and produce environment-friendly $H_2$, one of the promising routes is the sorption-enhanced steam reforming (SESR) process, in which the $CO_2$ sorbent is a key element. We prepared the $CO_2$ sorbents with $Ca_{12}Al_{14}O_{33}$ as carrier with various methods. Their characterizations were examined, and the sample prepared by solgel (SG) method showed the strongest CaO and $Ca_{12}Al_{14}O_{33}$ phases and the most excellent pore structure among all the samples. Then, a thermogravimetric experiment was conducted, and the results showed that the sample prepared by sol-gel (SG) method had the best $CO_2$ adsorption capacity and excellent long-term cyclic stability. Finally, the sorbent was used into the steam reforming experiments of tar. Under the action of the sorbent, the reforming reaction was enhanced in-situ, with the $H_2$ yield and concentration improved obviously, and especially, $H_2$ concentration can reach over 98.85%.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3338-3342
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• 2012

Covalent functionalization of a $B_{12}N_{12}$ nano-cage with $CO_2$ molecule has been investigated using density functional theory in terms of energetic, geometric, and electronic property analyses. Results show that besides two physisorption configurations, $CO_2$ preferably tends to perform [2+2] addition on B-N bonds of the cluster which are shared between six-membered and four-membered rings, releasing energy of 14.99 kcal/mol for adsorption of the first $CO_2$ and of 15.45 kcal/mol for the second one (per each molecule). On the basis of calculated density of states, we have found that the electronic properties of the physisorbed $B_{12}N_{12}$ by $CO_2$ have not changed, while slight changes have been predicted in the functionalized cases. Present results might be helpful to provide an effective way to modify the $B_{12}N_{12}$ properties for further purifications and applications.

• Analytical Science and Technology
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• v.37 no.1
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• pp.47-62
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• 2024

Abu Gurdi area is located in the South-eastern Desert of Egypt which considered as volcanic massive sulfide deposits (VMS). The present work aims at investigating the ore mineralogy of Abu Gurdi region in addition to the effectiveness of the hydrometallurgical route for processing these ores using alkaline leaching for the extraction of Zn, Cu, and Pb in the presence of hydrogen peroxide, has been investigated. The factors affecting the efficiency of the alkaline leaching of the used ore including the reagent composition, reagent concentration, leaching temperature, leaching time, and Solid /Liquid ratio, have been investigated. It was noted that the sulfide mineralization consists mainly of chalcopyrite, sphalerite, pyrite, galena and bornite. Gold is detected as rare, disseminated crystals within the gangue minerals. Under supergene conditions, secondary copper minerals (covellite, malachite, chrysocolla and atacamite) were formed. The maximum dissolution efficiencies of Cu, Zn, and Pb at the optimum leaching conditions i.e., 250 g/L NaCO₃ - NaHCO₃ alkali concentration, for 3 hr., at 250 ℃, and 1/5 Solid/liquid (S/L) ratio, were 99.48 %, 96.70 % and 99.11 %, respectively. An apparent activation energy for Zn, Cu and Pb dissolution were 21.599, 21.779 and 23.761 kJ.mol^-1, respectively, which were between those of a typical diffusion-controlled process and a chemical reaction-controlled process. Hence, the diffusion of the solid product layer contributed more than the chemical reaction to control the rate of the leaching process. High pure Cu(OH)₂, Pb(OH)₂, and ZnCl₂ were obtained from the finally obtained leach liquor at the optimum leaching conditions by precipitation at different pH. Finally, highly pure Au metal was separated from the mineralized massive sulfide via using adsorption method.

• Journal of the Korean Institute of Gas
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• v.23 no.6
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• pp.81-89
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• 2019

This study deals with a process for recovering hydrogen isotopes from fusion exhaust gas. The goal of this process is to remove impurities, maximally recover only pure hydrogen isotopes. Experiments using hydrogen and deuterium were conducted to confirm the possibility of the recovery of hydrogen isotopes. In the exhaust gas containing H₂, impurities was removed in the membrane process, and only pure H₂ was recovered. And the H₂ in the exhaust gas of the He-GDC(Glow Discharge Cleaning) process was recovered using a cryogenic adsorption process. In addition, HAZOP analysis was performed for qualitative risk assessment. For scenario analysis, the damage prediction ALOHA program was used to calculate the range of influence. Finally measures were sought to improve safety.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.73-74
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• 2013

In this study, we examined the properties of the concrete for the adsorption of carbon dioxide by adding in photosynthetic bacteria. As for the experimental plan, we measured slump, carbon dioxide concentration and compressive strength. The findings revealed the non-plastic cement added with photosynthetic bacteria had the greatest flexibility and showed carbon dioxide absorption and condensation delay due to the sugar constituents of photosynthetic bacteria. Giver the progress in the studies on the strength development, it is estimated to be used as CO₂ reduction concrete.

• Journal of the Korean Chemical Society
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• v.37 no.12
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• pp.1019-1024
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• 1993

The coadsorption of carbon monoxide and oxygen on polycrystalline nickel surface has been studied using XPS at the room temperaure. The adsorption of CO on the nickel surface precovered partially with oxygen is found to take place by the following steps: The CO molecules react with the preadsorbed oxygen atoms to liberate $CO_2$ gas at the initial stage of low CO exposures, and they are coadsorbed gradually with the increasing CO exposures. The extent of coadsorption at the higher CO exposures is found to decrease with the increasing degree of oxygen preadsorption. This finding is explained in terms of the reduced adsorption site for CO as a consequence of oxygen preadsorption. The CO molecules preadsorbed on the nickel surface inhibited the adsorption of $O_2$ molecules. The increase of oxygen exposure led to the dissociation of preadsorbed CO, and the NiO layers were formed concurrently. The dissociation was rendered to arise from an oxygen-to-CO energy transfer.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.252-261
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• 1997

The effect of solvent on the dispersion stability of $CaCO_3$ pigment in various solvents and resin solutions has been studied using Dynometer. Dispersion stability can be estimated in a relatively short time by means of Dynometer and the solubility parameter, ${\delta}$, of $CaCO_3$ determined from dispersion stability was 11.62(${\delta}_d=8.04$, ${\delta}_p=5.05$, ${\delta}_h=6.70$). The solvent showing weaker interaction with pigment increased the adsorption of resin on to the pigment, resulting in higher dispersion stability in resin solution. It was found that the rheological properties and dispersion stability of pigmented resin solution were depending strongly on the solvent added in small amount in the formulation.

• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4199-4204
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• 2011

Using models simulating the environment of two distinct adsorption sites of $H_2$ in metal-organic framework-5 (MOF-5), binding energies of $H_2$ to MOF-5 were evaluated at the MP2 and CCSD(T) level. For organic linker section modeled as dilithium 1,4-benzenedicarboxylate ($C_6H_4(COO)_2Li_2$), the MP2 and CCSD(T) basis set limit binding energies are estimated to be 5.1 and 4.4 kJ/mol, respectively. For metal oxide cluster section modeled as $Zn_4O(CO_2H)_6$, while the MP2 basis set limit binding energy estimate amounts to 5.4 kJ/mol, CCSD(T) correction to the MP2 results is shown to be insignificant with basis sets of small size. Substitution of benzene ring with pyrazine ring in the model for the organic linker section in MOF-5 is shown to decrease the $H_2$ binding energy noticeably at both the MP2 and CCSD(T) level, in contrast to the previous study based on DFT calculation results which manifested substantial increase of $H_2$ binding energies upon substitution of benzene ring with pyrazine ring in the similar model.

• Journal of Environmental Health Sciences
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• v.38 no.3
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• pp.261-268
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• 2012

Objectives: The photocatalytic degradation of toluene in a batch mode photoreactor for the purpose of the hazardous waste treatment was investigated. Methods: Kinetic experiments using a low pressure mercury lamp (Lambda Scientific Pty Ltd, 50 Watt) emitting both UV and visible light were performed at $31^{\circ}C$ over toluene concentrations ranging from 10 to 50 mg/l in water with $50%TiO_2/6%WO_3$ (TW) concentration of 1 g/l at a pH of 6. Results: Kinetic studies showed that $50%TiO_2/6%WO_3$ (TW) photocatalyst was highly active in toluene degradation; we observed that 99% of the pollutant was degraded after six hours under visible irradiation; furthermore, we observed that adsorption onto TW catalyst was responsible for the decrease of toluene with pseudo-first order kinetics. It was also found that oxygen as a radical source in the sol medium played a significant role in affecting the photodegradation of toluene, especially with a two-fold elevation. This increase was achieved by a more than four-fold elevation of the photodegradation of toluene in the presence of acetone than without, presumably via an energy transfer mechanism. Conclusions: We concluded that photodegradation in acetone and oxygen molecules along with TW was an effective method for the removal of toluene from wastewater.

• Membrane Journal
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• v.33 no.4
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• pp.168-180
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• 2023

H₂ generation from renewable sources is crucial for ensuring sustainable production of energy. One approach to achieve this goal is biohydrogen production by utilizing renewable resources such as biomass and microorganisms. In contrast to commercial methods, biohydrogen production needs ambient temperature and pressure, thereby requiring less energy and cost. Biohydrogen production can reduce greenhouse gas emissions, particularly the emission of carbon dioxide (CO₂). However, it is also associated with significant challenges, including low hydrogen yields, hydrodynamic issues in bioreactors, and the need for H₂ separation and purification methods to obtain high-purity H₂. Various technologies have been developed for hydrogen separation and purification, including cryogenic distillation, pressure-swing adsorption, absorption, and membrane technology. This review addresses important experimental developments in dense polymeric membranes for biohydrogen purification.