• Journal of the Korean Chemical Society
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• v.62 no.2
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• pp.79-86
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• 2018

This study reported the adsorption of Cu(II) ions onto activated carbon prepared from Myristica Fragrans shell (MFS AC) over independent variables of contact time, activating chemical (NaOH) concentration, initial adsorbate concentration, initial pH of adsorbate solution and adsorption temperature. The MFS AC structure, morphology and total surface area were characterized by FTIR, SEM and BET techniques, respectively. The Cu(II) ions adsorption on the MFS AC (activated using 0.5 M NaOH) fitted best to Freundlich adsorption isotherm (FAI), and the FAI constant obtained was 0.845 L/g at $30^{\circ}C$ and pH 4.5. It followed the pseudo first order of adsorption kinetic (PFOAK) model, and the PFOAK based adsorption capacity was 107.65 mg/g. Thermodynamic study confirmed the Cu(II) ions adsorption should be exothermic and non-spontaneous process, physical adsorption should be taken place. The total surface area and pore volume based on BET analysis was $99.85m^2/g$ and 0.086 cc/g, respectively.

• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.534-540
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• 2017

The adsorption of uranium (VI) by calcium alginate beads was examined by batch experiments. The effects of environmental conditions on U (VI) adsorption were studied, including contact time, pH, initial concentration of U (VI), and temperature. The alginate beads were characterized by using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. Fourier transform infrared spectra indicated that hydroxyl and alkoxy groups are present at the surface of the beads. The experimental results showed that the adsorption of U (VI) by alginate beads was strongly dependent on pH, the adsorption increased at pH 3~7, then decreased at pH 7~9. The adsorption reached equilibrium within 2 minutes. The adsorption kinetics of U (VI) onto alginate beads can be described by a pseudo first-order kinetic model. The adsorption isotherm can be described by the Redlich-Peterson model, and the maximum adsorption capacity was 237.15 mg/g. The sorption process is spontaneous and has an exothermic reaction.

• Journal of the Korean GEO-environmental Society
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• v.15 no.8
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• pp.39-44
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• 2014

Effects of operating parameters on the breakthrough properties of Pb(II) by $Mn_3O_4$ coated activated carbon prepared by supercritical technique were investigated through fixed-bed column experiments. The mass transfer zone and equilibrium adsorption capacity were enhanced about 2.8 times for Pb(II) by $Mn_3O_4$ coating onto activated carbon. Increase of bed height enhanced the residence time of Pb(II) in adsorption zone, giving the higher breakthrough time, mass transfer zone and equilibrium adsorption capacity. Increase of flow rate reduced the residence time and diffusion of Pb(II) in adsorption zone, therefore decreased the equilibrium adsorption capacity. The higher inlet concentration of Pb(II) decreased the breakthrough time and mass transfer zone through the promotion of Pb(II) transfer onto adsorbent.

• Journal of the Korea Concrete Institute
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• v.27 no.1
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• pp.85-92
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• 2015

The chloride ions, responsible for the initiation of the corrosion mechanism, intrude from the external medium into the concrete. A part of the intruding chloride ions will be retained by the hydration products of the binder in concrete, either through chemical adsorption or by physical adsorption. Since the hydration products of cement are responsible for the chloride binding in concrete, this study focused on the chloride binding in individual hydrate. The purpose of this study is to explore the time dependant behaviors of chloride ions adsorption with cement hydrates, focused on its mechanism. AFt phase and CH phase were not able to absorb chloride ion, however, C-S-H phase and AFm phase had a significant chloride adsorption capacity. In particular, AFm phase showed a chemical adsorption with slow rate in 40 days, while C-S-H phase showed binding behaviors with 3 stages including momentary physical adsorption, physico-chemical adsorption, and chemical adsorption. Based on the results, this study suggested theoretical approach to depict chloride adsorption behavior with elapsed time of C-S-H phase and AFm phase effectively. It is believed that the approach suggested in this study can provide us with a good solution to understand the mechanism on chloride adsorption with hydrates and to calculate a rate of chloride penetration with original source of chloride ions, for example, marine sand at initial time or sea water penetration later on.

• Journal of the Mineralogical Society of Korea
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• v.11 no.1
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• pp.20-31
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• 1998

Adsorption of metal elements onto illite and halloysite was investigated at $25^{\circ}C$ using pollutant water collected from the gold-bearing metal mine. Incipient solution of pH 3.19 was reacted with clay minerals as a function of time: 10 minute, 30 minute, 1 hour, 12 hour, 24 hour, 1 day, 2 day, 1 week, and 2 week. Twenty-seven cations and six anions from solutions were analyzed by AAs (atomic absorption spectrometer), ICP(induced-coupled plasma), and IC (ion chromatography). Speciation and saturation index of solutions were calculated by WATEQ4F and MINTEQA2 codes, indicating that most of metal ions exist as free ions and that there is little difference in chemical species and relative abundances between initial solution and reacted solutions. The adsorption results showed that the adsorption extent of elements varies depending on mineral types and reaction time. As for illite, adsorption after 1 hour-reaction occurs in the order of As>Pb>Ge>Li>Co, Pb, Cr, Ba>Cs for trace elements and Fe>K>Na>Mn>Al>Ca>Si for major elements, respectively. As for halloysite, adsorption after 1 hour-reaction occurs in the order of Cu>Pb>Li>Ge>Cr>Zn>As>Ba>Ti>Cd>Co for trace elements and Fe>K>Mn>Ca>Al>Na>Si for major elements, respectively. After 2 week-reaction, the adsorption occurs in the order of Cu>As>Zn>Li>Ge>Co>Ti>Ba>Ni>Pb>Cr>Cd>Se for trace elements and Fe>K>Mn>Al, Mg>Ca>Na, Si for major elements, respectively. No significant adsorption as well as selectivity was found for anions. Although halloysite has a 1:1 layer structure, its capacity of adsorption is greater than that of illite with 2:1 structure, probably due to its peculiar mineralogical characteristics. According to FTIR (Fourier transform infrared spectroscopy) results, there was no shift in the OH-stretching bond for illite, but the ν1 bond at 3695 cm-1 for halloysite was found to be stronger. In the viewpoint of adsorption, illite is characterized by an inner-sphere complex, whereas halloysite by an outer-sphere complex, respectively. Initial ion activity and dissociation constant of metal elements are regarded as the main factors that control the adsorption behaviors in a natural system containing multicomponents at the acidic condition.

• Journal of the Korean Society of Tobacco Science
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• v.35 no.1
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• pp.7-12
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• 2013

A Solid-phase micro extraction(SPME) was evaluated as a tool for headspace sampling of tobacco samples. Several experimental parameters (sampling temperature, pH, and type of SPME fibers) were optimized to improve sampling efficiency in two aspects ; maximum adsorption and selective adsorption of volatile organic acids onto SPME fibers. Among four types of SPME fibers such as PDMS(Polydimethylsiloxane), PA(Polyacrylate), Car/PDMS (Carboxen/Polydimethylsiioxane) and PDMS/DVB(Polydimethylsiioxane/Divinylbenzene) which were investigated to determine the selectivity and adsorption efficiency. A variety of tobacco samples such as flue cured, burley and oriental were used in this study. The effect of these parameters was often dominated by the physical and chemical nature (volatility, polarity) of target compounds. This method allowed us to make important improvements in selectivity and sensitivity. The Car/PDMS fiber was shown to be the most efficient at extracting the 10 selected volatile organic acids. The parameters were optimized: $80^{\circ}C$ adsorption temperature, 30 min of adsorption time, $240^{\circ}C$ desorption temperature, 1 min of adsorption time.

• Carbon letters
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• v.10 no.4
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• pp.293-299
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• 2009

Potassium hydroxide activated carbons were prepared from Egyptian petroleum cokes with different KOH/coke ratios and at different activation temperatures and times. The textural properties were determined by adsorption of nitrogen at $-196^{\circ}C$. The adsorption of iodine and methylene blue was also investigated at $30^{\circ}C$. The surface area and the non-micropore volume increased whereas the micropore volume decreased with the increase of the ratio KOH/coke. Also the surface area and porosity increased with the rise of activation temperature from 500 to $800^{\circ}C$. Textural parameter considerably increased with the increase of activation time from 1 to 3 h. Further increasing of activation time from 3 to 4 h was associated with a less pronounced increase in textural parameters. The adsorption of iodine shows the same trend of surface area and porosity change exhibited by nitrogen adsorption, with KOH/coke ratio and temperature of activation. Adsorption of methylene blue follows pseudo-first-order kinetics and its equilibrium adsorption follows Langmuir and D-R models.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2009.10a
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• pp.79-84
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• 2009

Understanding the polymer adsorption in particle/binder/solvent system is important to achieve successful film products. While most of the reported work has dealt with the suspension microstructure, a few studies have focused on film formation. We investigated the effect of adsorption on film formation through measurement of adsorption amount in suspension and stress development in drying film with respect to mixing time ($t_m$). All of the adsorption amount (PVA), characteristic stress ($\sigma_{ch}$) exhibited similarities expressed by the form of $1-e^{t_m/{\tau}}$. The porous and non-unifonn dried film at short tm became close-packed and uniform with longer $t_m$. We found that polymer adsorption plays the key role in film fonnation as it introduces steric repulsion in suspension and suppresses the flocculation during solvent evaporation. We also found that the mixing time for the saturated polymer adsorption is the important variable to acquire the consolidated and uniform film microstructure.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.7
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• pp.64-70
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• 2022

The aim of this study is to improve the purification efficiency of odor gas by increasing the contact area between an odor gas and adsorbent. To analyze the flow in the adsorption tower, the flow characteristics in the hollow activated carbon-adsorption tower are identified by applying the loss model, which is a porous flow analysis model. The flow characteristics are investigated for pressure loss, velocity distribution, turbulent kinetic energy, and residence time distribution. The results show that the hollow adsorption tower performs better than the solid adsorption tower in terms of pressure loss and performance. The inner diameter of the hollow region inside the adsorption tower is 0.64 m (Di/Do = 0.37). Furthermore, the adsorbent performance is unaffected even when adsorbent stages are installed to replace the adsorbent.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.141-146
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• 2011

Loess, a natural clay, was evaluated as an adsorbent for the decolorization of Acid Orange II, an azo and reactive dye, from aqueous solution. Adsorption studies were performed at $30^{\circ}C$ and the effect of reaction time, loess dosage, initial concentration, loess particle size, pH, agitation rate were investigated to determine the optimum operation conditions. The removal efficiencies of color were measured to evaluate the effectiveness of loess. From this study, it was found that optimal reaction time was 10 min. Color removal efficiencies of Acid Orange II were increased as higher loess dosage, initial concentration and agitation rate. However, color removal efficiencies decreased when pH is high and loess particle becomes large. Adsorption of Acid Orange II fitted to the pseudo-second-order rate kinetics more than first-order rate kinetics. Langmuir and Freundlich adsorption isotherm constants and correlation coefficients were calculated and compared. It was concluded that the adsorption data of Acid Orange II onto loess fitted to the Freundlich model more than Langmuir model.