• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.495-501
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• 2011

The corrosion inhibitive nature of a flavonoid compound, 3-Hydroxy-7-methoxy-2-phenylchromen-4-one (HMPC), the synergistic effect between HMPC and n-Tetrabutylammonium bromide (TBAB) and their adsorption behavior on mild steel in hydrochloric acid solution were studied by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The results of weight loss study at different temperatures revealed that the inhibition efficiency increases with inhibitor concentration and decreases with increase in the temperature of the system. The electrochemical studies showed that the inhibitor acts through mixed mode of inhibition and the inhibitor molecules adsorb on the metal - solution interface forming a protective layer. The adsorption of the inhibitor molecules over the metal surface was supported by the obeyed Langmuir's adsorption isotherm, Scanning Electron Microscopic analysis (SEM) and Fourier Transform Infrared (FT-IR) spectroscopic studies.

• Economic and Environmental Geology
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• v.36 no.5
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• pp.381-385
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• 2003

We investigated possible application of waste ferrite in treating Cd and Pb in wastewater. Adsorption of Cd and Pb on Mn-Ferrite are influenced by several controlling factors such as contact time, heavy metal concentrations, pH and temperature. Both Cd and Pb achieved adsorption equilibrium within 5 minutes. Based upon this kinetic data, 24 hours of contact time was allowed for other experiment. The adsorption of Cd and Pb was high at high pH and high ion concentrations. The reaction was also affected by temperature. Adsorption isotherms fits well with the Freundlich isotherm equation. pH is the main controlling factor in Cd, Pb adsorption on the Mn-ferrite. Cd showed S type adsorption curve while Pb showed sorption edges, depending on the Pb concentrations.

• Journal of the Mineralogical Society of Korea
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• v.27 no.1
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• pp.41-51
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• 2014

The four natural zeolites collected in Pohang and Gyeongju area, Kyungsangbuk-do, Korea, were characterized by XRD, XRF, DTA, TGA, and CEC analysis. The primary species of these zeolite are heulandite, modenite, illite, and illite in Kuryongpo (Ku), Pohang (Po), Yangbuk-A (Ya-A), and Yangbuk-B (Ya-B) samples. The XRF analysis showed that the four zeolites contain Si, Al, Na, K, Mg, Ca, and Fe. Cation exchange capacity of Kuryongpo (Ku) zeolite was the highest compared to other zeolites. The adsorption capacities of Cs and Sr in the four natural zeolites were compared at $25^{\circ}C$. On the basis of adsorption data Langmuir and Freundlich adsorption isotherm model were confirmed. The equilibrium process was descried well by Langmuir isotherm model. This study shows that Ya-A zeolite is the most efficient for the $Cs^+$ and $Sr^{2+}$ ion adsorption compared to the other natural zeolites.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.76-81
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• 1998

Physical adsorption on a silica gel(pore size of 80 nm, particle size of $10{\mu}m$)has been studied for binary mixture of acetone diluted in $CO_2$ by use of a FTIR transmission technique and we have compared the result of FTIR transmission technique with that of a chromatographic technique. Measurements were made at 313.2 K and under pressures up to 15MPa. As the pressure increases from 0.1MPa, the IA(Integral Absorbance) of the hydrogen-bonded OH groups interacting with acetone and adsorbed amount by use of a chromatographic technique increases at first, and reaches a maximum at a pressure below the critical pressure of $CO_2$, and then the intensities decrease gradually with increasing pressure. It is found that the pressure dependency of the chromatographic isotherm is a little larger than that of spectroscopic isotherm in the supercritical fluid region. This difference might be attributable to the weaker van der Waals force and relatively stronger hydrogen-bonding force influencing the adsorption of acetone on the sllica gel. The unique spectroscopic characteristics of amine group which vibrational frequencies of hydroxyl groups on the silica gel surface shift downward to about $1300cm^{-1}$ were measured from experimental result of triethylamine diluted in $CO_2$ or $N_2$.

• Journal of Radiation Protection and Research
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• v.27 no.1
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• pp.27-35
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• 2002

Characteristics of Amberlite IRN 77, a cation exchange resin, and the mechanisms of its adsorption equilibria with Co(II), Ni(II), Cr(III) and Fe(III) ions were investigated for the application of the demineralizing process in the primary coolant system of a pressurized water reactor (PWR). The optimum dosage of the resin for removal of the dissolved metal ions at $200mgL^{-1}$ was 0.6 g for 100 mL solution. Most of each metal ion was adsorbed onto the resin in an hour from the start of the reaction. Each metal adsorption onto the resin could be well represented by Langmuir isotherms. However, in the case of Fe(III) adsorption, continuous formation of Fe-oxide or -hydroxide and its subsequent precipitation inhibited the completion of the equilibrium between the metal and the adsorbent Cobalt(II) and Ni(II), which have an equivalent electrovalence, were adsorbed to the resin with a similar adsorption amount when they coexisted in the solution. However, Cr(III) added to the solution competitively replaced Co(II) and Ni(II) which were already adsorbed onto the resin, resulting in desorption of these metals into the solution. The result was likely due to a higher adsorption affinity of Cr(III) than Co(II) and Ni(II). This implies that the interactively competitive adsorption of multi-cations onto the resin should be fully considered for an efficient operation of the demineralizing ion exchange process in the primary coolant system.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.113.2-113.2
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• 2010

We report that the novel covalent organic frameworks (COFs) are capable of reversibly providing an extremely high uptake capacity of carbon dioxide and hydrogen at room temperature. These COFs are designed based on the multiscale simulations approach via the combination of ab initio calculations and force-field calculations. For this goal, we explore the adsorption sites of carbon dioxide and hydrogen on COFs, their porosity, as well as carbon dioxide adsorption isotherms. We identify the binding sites and energies of $CO_2$ on COFs using ab initio calculations and obtain the carbon dioxide adsorption isotherms using grand canonical ensemble Monte Carlo calculations. Moreover, the calculated adsorption isotherms are compared with the experimental values in order to build the reference model in describing the interactions between the $CO_2/H_2$ and the COFs and in predicting the $CO_2$ and $H_2$ adsorption isotherms of COFs. Finally, we design three new COFs, 2D COF-05, 3D COF-05 (ctn), and 3D COF-05 (bor), for the high capacity $CO_2/H_2$ and $H_2$ storage.

• Korean Journal of Materials Research
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• v.23 no.8
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• pp.462-468
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• 2013

We study and describe-from the point of view of the interactions of the adsorbed particles-three types of the adsorption isotherms, namely, Langmuir type adsorption isotherms, phase transition type adsorption isotherms, and adsorption limited type adsorption isotherms, which are observed by experiments. By introducing and using a one dimensional statistical occupancy model, we derived analytical adsorption isotherms for the no force, the attractive force, and the repulsive force exerted on the other adsorbed particles. Our derived adsorption isotherms qualitatively pretty well agree with the experimental results of the adsorption isotherms. To specify each adsorption type, Langmuir type adsorption is a phenomenon that occurs with no forces between the adsorbed particles, phase transition type adsorption is a phenomenon that occurs with the strong attractive forces between the adsorbed particles, and adsorption limited type adsorption is a phenomenon that occurs with the repulsive forces between the adsorbed particles. The theoretical analysis-only using fundamental thermodynamics and occupancy statistics though-qualitatively quite well explains the experimental results.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.1
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• pp.19-25
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• 2017

In this study, a electrostatic filter which could be applicable to road environment was developed and evaluated in adsorption capacity. The evaluation were performance for removal by particle size and adsorption amount by pressure using ASERAE 52.1 and 52.2. The range of size for removal test was $0.3{\mu}m{\sim}10.0{\mu}m$ which had 12 steps. The filter showed 91.3% removal efficiency from $2.5{\mu}m$ and under the size, average 53.5% proportional to decreasing size value. The weight removal was 96.7% from 22.6 mmaq, initial pressure to 35 mmaq, end pressure with $715.9g/m^2$, the adsorption amount. The shape of isotherm was expressed as Langmuir's one. After washing saturated filter with dust to end pressure, the initial pressure and adsorption amount of the filter showed a light drop with no removal efficiency decline.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.3
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• pp.162-166
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• 2011

Phosphorous contaminated in the effluent from sewage treatment plants can cause the eutrophication in surface water bodies. In this study, a powder of titanium oxysulfate-sulfuric acid made of ion-exchange materials was immobilized in an alginate gel and this material was examined to evaluate its phosphorous removal efficiency. Equilibrium and kinetic studies were carried out to quantify the adsorption capacity and time dependent removal rate of phosphorous. Adsorption isotherms and kinetic parameters were obtained for the entrapped titanium beads with three different methods. Equilibrium data were analyzed using Langmuir adsorption isotherm model and found to be well fitted to the model. The maximum adsorption capacity for phosphorous by the titanium bead synthesized with the solution method was 92.26 mg/g. Kinetic data followed a pseudo-second-order kinetic model. Due to the low production cost and high adsorption capacity, the titanium bead synthesized by the solution method has a potential to be utilized for the cost-effective removal of phosphorous from wastewater.

• Clean Technology
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• v.29 no.3
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• pp.217-226
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• 2023

The amount of hydrogen adsorbed in arrays of single walled carbon nanotubes (SWNTs) was studied as a function of nanotube diameter and distance between the nearest-neighbor nanotubes on square arrangements using a grand canonical Monte Carlo simulation. The influence of the geometry of a triangle array with the same diameters and distances was also studied. Hydrogen-carbon and hydrogen-hydrogen interactions were modeled with Lennard-Jones potentials for short range interactions and electrostatic interactions were added for hydrogen-hydrogen pairs to consider quantum contributions at low temperatures. At 194.5 K, Type I isotherms for large-diameter SWNTs and Type IV isotherms without hysteresis between adsorption and desorption processes for wider tube separations were observed. At 200 bars, the gravimetric hydrogen storage capacity of the SWNTs was reached or exceeded the US Department of Energy (DOE) target, but the volumetric capacity was about 70% of the DOE target. At 77 K, a two-step adsorption was observed, corresponding to a monolayer formation step followed by a condensation step. Hydrogen was adsorbed first to the inner surface of the nanotubes, then to the outer surface, intratubular space and the interstitial channels between the nanotube bundles. The simulation indicated that SWNTs of various diameters and distances in a wide range of configurations exceeded the DOE gravimetric and volumetric targets at under 1 bar.