• Membrane and Water Treatment
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• v.7 no.1
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• pp.39-53
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• 2016

In this study, polysufone (PSf) was used as a base polymer to synthesize sulfonated polysulfone (SPSf) and aminated polysulfone (APSf) as cation and anion exchange polymers, respectively. Then the ion exchange polymers were coated onto the surface of commercial carbon electrodes. To compare the capacitive deionization (CDI) and membrane capacitive deionization (MCDI) processes, the pristine carbon electrodes and ionic polymer coated electrodes were tested under various operating conditions such as feed flow rate, adsorption time at fixed desorption time, and feed concentration, etc., in terms of effluent concentration and salt removal efficiency. The MCDI was confirmed to be superior to the CDI process. The performance of MCDI was 2-3 times higher than that of CDI. In particular, the reverse desorption potential was a lot better than zero potential. Typically, the salt removal efficiency 100% for 100 mg/L NaCl was obtained for MCDI at feed flow rate of 15 ml/min and adsorption/desorption time of 3 min/1 min and applied voltages 1.0 V for adsorption and -0.3 V for desorption process, and for 500 mg/L, the salt removal efficiency 91% was observed.

• Membrane Journal
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• v.29 no.6
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• pp.355-361
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• 2019

We studied the removal of barium ions that may be contained in industrial wastewater using the existing capacitive deionization (CDI). The 30 mg/L BaCl₂ (barium chloride dihydrate) solution was used as the feed solution, and the flow rate was set to 10 mL/min. The adsorption conditions were varied from 1.2 V to 3, 5 and 7 min, and the desorption conditions were -1, -1.5, -2 V and 1, 2 and 3 min, respectively, to select the most efficient conditions. As a result, barium ion removal efficiency of 64.4% was obtained under the adsorption conditions of adsorption of 1.2 V/7 min and the desorption -1 V/1 min. For the desorption voltages and time, under the same experimental conditions, the removal efficiency of CDI for 30 mg/L NaCl aqueous solution with the same concentration as barium showed 69.9% removal efficiency under the adsorption conditions of and the desorption conditions of 1.2 V/7 min desorption -1 V/1 min, respectively.

• Journal of Environmental Science International
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• v.25 no.3
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• pp.395-403
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• 2016

This study examined the adsorption effect of aromatic pesticides by hollow fiber NF membrane on rejection and removal properties. Batch type adsorption test and hollow fiber NF membrane filtration were conducted with 5 different kinds of aromatic pesticides. 3 to 15 days were required to reach the equilibrium concentration and $0.3181{\sim}0.8094{\mu}g/cm^2$ were adsorbed to hollow fiber NF membrane. Since 5 hours of separation test were too short to keep steady state for permeate due to the repetition of sorption and desorption, longer times were required to evaluate the rejection performance of NF membrane. Sorption and desorption were confirmed by the separation test equipped with membrane and without membrane. Adsorption contribution of aromatic pesticides to hollow fiber membranes were shown to be ranged from 16.1% to 36.3% and indicated the difference considering sorption effect.

• Nuclear Engineering and Technology
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• v.32 no.5
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• pp.504-513
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• 2000

The adsorption characteristics of methyl iodide generated from the simulated off-gas stream on various adsorbents such as silver ion-exchanged zeolite (AgX), zeocarbon and activated carbon were investigated. An extensive evaluation was made on the optimal silver ion-exchanged level for the effective removal of methyl iodide at temperature up to 38$0^{\circ}C$. The degree of adsorption efficiency of methyl iodide on silver ion-exchanged zeolite is strongly dependent of silver ion-amount and process temperature. The influence of temperature, methyl iodide concentration and silver ion-exchanged level on the adsorption efficiency is closely related to the pore characteristics of adsorbents. It would be facts that the effective silver ion-exchanged level was about 10 wt%, based on the degree of silver utilization for the removal of methyl iodide.

• Mass Spectrometry Letters
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• v.15 no.1
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• pp.54-61
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• 2024

An improved voltage modulation method (VMM) was used to control the heat release and adsorption properties of the adsorbent. In this work, the voltage and flux modulation methods were considered under unified experimental conditions of dissociative surface ionization (SI) of polyatomic organic molecules, the criteria were found when under VMM conditions the current relaxation of SI carries information about the kinetic properties of thermal desorption of ionizable dissociation particles arriving on the surface of polyatomic molecules. Conditions were found under which the relaxation of the ionic current in the flux modulation method is determined by the kinetics of the heterogeneous dissociation reaction of the original polyatomic molecules. The values of the thermal desorption rate constant K⁺ and the activation energy E⁺ obtained with VMM for desorption of (CH₃)₂NCH⁺₂ ions with m/z 58 by adsorption of imipramine and amitriptyline molecules agree well with each other and with the results for the desorption of the same ions by adsorption of other molecules. This confirms one of the basic conditions for the equilibrium process SI - the a degree (β coefficient) of the same particles SI on the same emitter surface is the same and does not depend on the way these particles are formed on the emitter surface.

• Bulletin of the Korean Chemical Society
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• v.30 no.6
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• pp.1353-1356
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• 2009

This study examined the adsorption of CO on a Mo(110) surface by Thermal Desorption Spectroscopy (TDS) and synchrotron-radiation based photoemission spectroscopy (SRPES). CO desorption was observed at approximately 400 K ($\alpha$-CO) and > 900 K ($\beta$-CO). When CO was exposed to Mo(110) at 100 K, it showed a tilted structure at low CO coverage and a vertical structure after saturation of the tilted CO. After heating the CO-precovered sample to 900 K, a broad peak at 12 eV below the Fermi level was identified in the valence level spectra, which was assigned to either the 4$\sigma$-molecular orbital of CO, or 2s of dissociated carbon. TDS results of the $\beta$-CO showed a first order desorption. These results are in a good agreement with the observations of CO adsorption on W(110) surfaces.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.5
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• pp.575-584
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• 2007

The adsorption capability of iron phthalocyanine derivatives were investigated by means of X-ray diffractometor (XRD), IR (infrared) spectroscopy, scanning electron microscopy (SEM) and temperature programmed desorption (TPD). According to TPD results, iron phthalocyanine derivatives showed two desorption peaks at low temperature ($100{\sim}150^{\circ}C$) and high temperature ($350{\sim}400^{\circ}C$) indicating that there were two kinds of acidities. Tetracarboxylic iron phthalocyanine (Fe-TCPC) have a stronger desorption peak (chemical adsorption) at the high temperature and a weaker desorption peak (physical adsorption) at the low temperature than iron phthalocyanine (Fe-PC). The specific surface areas of Fe-TCPC and Fe-PC were $26.46\;m^2/g\;and\;11.77\;m^2/g$, respectively. The pore volumes of Fe-TCPC and Fe-PC were $0.14\;cm^3/g\;and\;0.06\;cm^3/g$, respectively. The adsorption capability of triethyl amine calculated by breakthrough curve at 220 ppm of equilibrium concentration was 29.2 mmoL/g for Fe-TCPC and 0.8 mmoL/g for Fe-PC. The removal efficiency of dimethyl sulfide of Fe-TCPC and Fe-PC in batch experiment of 225 ppm of initial concentration were 44.9% and 28.9%, respectively. The removal efficiency of trimethyl amine of Fe-TCPC and Fe-PC in batch experiment of 118 ppm of initial concentration were approximately 100.0% and 33.9%, respectively.

• Journal of Environmental Science International
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• v.31 no.2
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• pp.171-180
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• 2022

Zeolitic material, Z-Y3, was synthesized from coal fly ash (CFA) under low-alkaline conditions (NaOH/CFA ratio = 0.3 and NaOH solution concentrations of 0.0, 0.5, and 1.0 M) using a fusion/hydrothermal method. The adsorption capacities of the fabricated Z-Y3 samples for Cs and Sr ions and the desorption capacity of Na ions were evaluated. The XRD patterns of the Z-Y3 sample fabricated using a 1.0 M NaOH solution (Z-Y3 (1.0 M)) indicated the successful synthesis of a zeolitic material, because the diffraction peaks of Z-Y3 coincided with those of the Na-A zeolite in the 2θ range of 7.18-34.18. Moreover, the SEM images revealed that morphology of the Z-Y3 (1.0 M) sample, which presented zeolitic materials characteristics, consisted of sharp-edged cubes. The adsorption isotherms of Cs and Sr ions on all the fabricated Z-Y3 samples were described using the Langmuir model, and the maximum adsorption capacities of Cs and Sr were calculated to be 0.14-0.94 mmol/g and 0.19-0.78 mmol/g, respectively. The desorption of Na ions from the Cs and Sr ions adsorbed Z-Y3 samples followed the Langmuir desorption model. The maximum desorption capacities of Na ions from the Cs and Sr ions adsorbed Z-Y3 (1.0 M) samples were 1.28 and 1.49 mmol/g, respectively.

• Journal of Soil and Groundwater Environment
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• v.18 no.7
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• pp.81-89
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• 2013

Concerns have been raised over the impact of nano materials on soil and groundwater environment with the increasing attention to the potential applications of carbon nano materials in various fields. Particularly, carbon nano materials introduced into water environment readily make complexes with humic acid (HA) due to their hydrophobic nature, so there have been increasing numbers of studies on the interaction between HA and carbon nano materials. In this study, we investigated the solubility of HA and multiwalled carbon nanotubes (MWCNT) in three different surfactant solutions of sodium dodecyl sulfate (SDS), Brij 30 and Triton X-100, and evaluated whether the HA can be effectively desorbed from the surface of MWCNT by surfactant. The objective of this study was to determine the optimal adsorption condition for HA to MWCNT. Futhermore, sodium dodecyl sulfate (SDS), Brij 30, Triton X-100 were used to elucidate the effect of desorption and separation on adsorbed HA on MWCNT. As a result, HA solution with 12.7 mg of total organic carbon (TOC) and 5 mg of MWCNT showed the highest adsorption capacity at pH 3 reacted for 72 hrs. Weight solubilizing ratio (WSR) of surfactants on HA and MWCNT was calculated. HA had approximately 2 times lower adsorption capacity for the applied three surfactants compared to those of MWCNT, implying that the desorption of HA may occur from the HA/MWCNT complex. According to the results of adsorption isotherm and weight solubilizing ratio (WSR), the most effective surfactants was the SDS 1% soluiton, showing 53.63% desorption of HA at pH 3.

• Clean Technology
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• v.20 no.2
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• pp.179-188
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• 2014

The effect of desorption pressure on $CO_2/N_2$ breakthrough behaviors for 4 different adsorbents was studied at a fixed bed. Zeolite 3A, 4A, 5A, and 13X pellets were used as adsorbents. Cyclic operations were executed with varying desorption pressure from vacuum (0 bar) to 3 bar while other conditions such as adsorption step pressure (3 bar), temperature (293 K), composition ($CO_2:N_2=10:90$vol%) and flow rate (400 ccm) were fixed at constant values. Each adsorption and desorption step was set as 80 min, which totaled up to 160 min per a cycle. 5 cycles with adsorption and desorption steps were run overall. After the experiment, breakthrough time, saturation time, and adsorption amount were measured and compared in order to find an optimum adsorbent and a proper operating condition for a post combustion $CO_2$ capture process.