• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4022-4029
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• 2022

We investigated the possibility of using graphene for control of hydrogen isotopes by exploring adsorption, reflection, and penetration of hydrogen isotopes on graphene using molecular dynamics. Reflection is the dominant interaction when hydrogen isotopes have low incident energy. Adsorption rates increase with increasing incident energy until 5 eV is reached. After 5 eV, adsorption rates decrease as incident energy increases. At incident energies greater than 5 eV, adsorption rates increase with the number of graphene layers. At low incident energies (<1 eV), no isotopic effects on interactions are observed since the predominant interaction is derived from the force of π electrons. Between 1 eV and 50 eV, heavier isotopes exhibit higher adsorption rates and lower reflection rates than lighter isotopes, due to the greater momentum of heavier isotopes. Adsorption rates are consistently higher when the incident angle of the impacting atoms is smaller between 0.5 eV and 5 eV. At higher energies (>5 eV), larger incident angles lead to higher reflection and lower penetration rates. At high incident energies (>5 eV), crumpled graphene has higher adsorption and lower penetration rates than wrinkled or unwrinkled graphene. The results obtained in this research study will be used to develop novel nanomaterials that can be employed for tritium control.

• Journal of the Korean Society of Safety
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• v.14 no.3
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• pp.127-133
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• 1999

One of the major malodorous gas at the working place is hydrogen sulfide and impregnated activated carbon fiber(ACF) was used as a adsorbent to remove this gas. ACF is treated and impregnated with chemicals to increase the adsorption capacity. The experiments showed that the adsorption efficiency for hydrogen sulfide was increased in case of impregnation with $Na_2CO_3$ or KI. Also, by the surface treatment with NaOH, the adsorption efficiency was increased however not so much as impregnation. KI was the best impregnant for this purpose and the optimum concentration was 9wt%. The adsorption capacity of hydrogen sulfide was more than 500mg/g ACF.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.312-315
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• 2018

Although the reversibility of 10,12-pentacosadiynoic amino meta-acid(PCDA-mBzA) against temperature and pH was reported, the modulation of reversibility by ion adsorption at terminal functional group has not been investigated. In this work, we developed a simple method for modulating the reversibility of PCDA-mBzA films upon a thermal stimulus by cadmium ion adsorption inducing the breakage of the outer hydrogen bonding of two hydrogen bonds, which are responsible for the reversible properties of PCDA-mBzA. External reflection-Fourier transform infrared (ER-FTIR) analyses revealed that the hydrogen bonding between the carboxylic acid groups was broken through ion adsorption and only a single hydrogen bond between the amide groups remained in the PCDA-mBzA polymer. In addition, PCDA-mBzA films could recover their original property through cadmium ion desorption. These results present that the transition between reversibility and irreversibility can be modulated artificially simply through the adsorption and desorption of metal ions.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1596-1600
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• 2010

Surface functionalization of multi-walled carbon nanotubes (MWNTs) was carried out by means of acid treatment. The presence of oxygen functional groups on the surface of acid-treated MWNTs was confirmed with the aid of Fourier transform infrared spectroscopy and X-ray spectroscopy. In addition, carboxylic groups generally formed on the surface of acid-treated MWNTs, and the dispersion was increased by the duration of the acid treatment. The zeta-potential indicated the surface charge transfer and the dispersion of MWMTs. Morphological characteristics of acid-treated MWNTs were also observed using a transmission electron microscopy, X-ray diffraction, and Raman analysis, which was revealed the significantly unchanged morphologies of MWNTs by acid treatment. The hydrogen adsorption capacity of the MWNTs was evaluated by means of adsorption isotherms at 77 K/1 atm. The hydrogen storage capacity was dependent upon the acid treatment conditions and the formation of oxygen functional groups on the MWNT surfaces. The latter have an important effect on the hydrogen storage capacity.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.1
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• pp.8-20
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• 2006

For large scale separation hydrogen from different mixing ratio(60/40 and 80/20 vol.%) of hydrogen and methane $1Nm^3/hr$ and $4Nm^3/hr$ 2bed-6step pressure swing adsorption(PSA) process was used, respectively. The effects of the feed gas pressure, adsorption time, the feed flow rate and the P/F(purge to feed) ratio on the process performance were evaluated. In the $1Nm^3/hr$ PSA results, 11 atm adsorption pressure and 0.10 P/F ratio might be optimal values to obtain more than 75 % recovery and 99 % purity hydrogen in these processing. The optimum feed flowrate was 22 LPM and 17 LPM in the ratio 60/40 and 80/20, respectively. In the $4Nm^3/hr$ PSA results, 10 atm adsorption pressure might be simulated values to obtain more than 80 % recovery and 99 % purity hydrogen in these processing.

• Bulletin of the Korean Chemical Society
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• v.23 no.12
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• pp.1765-1768
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• 2002

The isotherms of CO adsorption on the Cu/ZnO sample treated with with hydrogen and methanol are investigated. The heats of adsorption of CO on the Cu/ZnO treated with hydrogen at 723K for 3 h are in the range from 25.7 kJ/mol at $\theta=0.8$ to 59.8 at $\theta=0.1$, while those on the Cu/ZnO sample treated with methanol at 523 K for 3 h are in the range 30.3 kJ/mol at $\theta=0.8$ to 99.8kJ/mol at $\theta=0.1.$ The Cu/ZnO samples treated with hydrogen do. The heats of adsorption at q=0.1 increase with the methanol treatment time within 30 min and leveled off afterwards.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.2
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• pp.180-190
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• 2005

The PSA cycle was performed for the separation of binary gas mixture $H_2/Ar$ (80%/20%) using the six-step two-bed process. Adsorption equilibrium contains a LRC model for equilibrium adsorption isotherms and a LDF model for mass transfer. Aspen ADSIM, simulator was applied to predict the separation performance. The effect of cycle parameters such as feed rate, adsorption pressure and P/F ratio on the separation of hydrogen has been studied in experiment and simulation. In the results, maximize the recovery of hydrogen as a high purity was 13LPM feed flowrate, 120sec adsorption time, 11atm adsorption pressure and 0.1 P/F ratio in a cyclic steady-state come out since 10th cycle.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1229-1230
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• 2006

Adsorption isotherms of hydrogen by step-by-step method are widely used. However, the relations between the equations of state and the accumulated errors produced by step-by-step method and the mechanical errors of pressure or temperature controller were not analyzed. Considering the influence of various errors on the equations of state, we could find out the factors and compare the performance of the equations of state.

• Journal of the Korean Applied Science and Technology
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• v.20 no.1
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• pp.72-79
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• 2003

The impregnated activated carbons were prepared by the incipient wetness method with the contents of $KIO_3$ varied from 1.0${\sim}$10 wt% as the impregnation material. The specific surface area and micropore volume of the rice hulls activated carbon were $2,600{\sim}2,800$ $m^2$/g and 1.1${\sim}$1.4 cc/g, respectively. With increasing the contents of impregnation materials, the surface area and micropore volume decreased by 3${\sim}$21%. However, The amounts of hydrogen sulfide adsorbed increased by 2.1${\sim}$2.8 times depending on the impregnation content. The optimum contents of $KIO_3$ were 2.4 wt%. Although the breakthrough time and adsorption capacity of hydrogen sulfide decreased with increasing temperature in the case of the unimpregnated activated carbons, they increased by 1.2${\sim}$ 3.2 times for the case of the impregnated activated carbons. The optimum aspect ratio(L/D) was 1.0 and the adsorption amount of hydrogen sulfide enhanced with increasing the gas flow rate. The regeneration temperature was determined as 400$^{\circ}C$ from the TGA experiment. The adsorption capacity of hydrogen sulfide with the impregnated activated carbon decreased gradually as the regeneration continued. The hydrogen sulfide adsorption amount of the regenerated activated carbon up to 4 times was still higher than that of the unimpregnated activated carbon.

• Journal of the Korean Vacuum Society
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• v.14 no.2
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• pp.69-77
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• 2005

Pumping performance of large cryosorption pumps of different types installed on the 60 $m^3$ test stand for developing and testing ion sources and beam line components of the NBI system was investigated. Hydrogen adsorption and desorption characteristics of the cryosorption panels were analyzed using the temporal change of the hydrogen spectrum obtained with short introduction of the hydrogen gas as cooling the panel, and simulations on the mutual influence between related parameters were also carried out.