• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.941-946
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• 2009

Two types of synthetic zeolites, commercially used (Z-WK) and synthesized by coal fly ash (Z-C1), and raw coal fly ash(F-C1) were examined for its kinetics and adsorption capacities of cobalt. Experimental data are fitted with kinetic models, Lagergen $1^{st}$ and $2^{nd}$ order models, and four types of adsorption isotherm models, Langmuir, Freundlich, Redlich-Peterson, and Koble-Corrigan. Synthesized zeolite (Z-C1) which had 1.51 of Si/Al ratio was synthesized by raw coal fly ash from a thermal power plant. Adsorption capacities with three types of adsorbents, Z-WK, Z-C1, and F-C1, were in the order of Z-C1 (94.15 mg/g) > F-C1 (92.94 mg/g) > Z-WK (88.56mg/g). The adsorption kinetics of Z-WK and Z-C1 with cobalt could be accurately described by a pseudo-second-order rate equation. The adsorption isotherms of Z-WK and Z-C1 with cobalt were well fitted by the Langmuir and Redlich-Peterson equation. Z-C1 will be used to remove cobalt in water as a more efficient absorbent.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.1
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• pp.3-10
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• 2016

Effects of acid ($HNO_3$ and HCl) modification on the adsorption properties of Pb(II) and Cu(II) onto bamboo-based activated carbon (BAC) were investigated through a series of batch experiments. The carbon content increased and oxygen content decreased with acid treatment. $HNO_3$ induced carboxylic acids and hydroxyl functional groups while HCl added no functional group onto BAC. The pseudo-second order model better described the kinetics of Pb(II) and Cu(II) adsorption onto experimented adsorbents, indicating that the rate-limiting step of the heavy metal sorption is chemical sorption involving valency forces through sharing or exchange of electrons between the adsorbate and the adsorbent. The equilibrium sorption data followed both Langmuir and Freundlich isotherm models. The adsorption capacities of BAC were affected by the surface functional groups added by acid modification. The adsorption capacities were enhanced up to 36.0% and 27.3% for Pb(II) and Cu(II), respectively by the $HNO_3$ modification, however, negligibly affected by HCl.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.1
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• pp.59-63
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• 2016

The objective of this study lies in identifying the applicability of zeolite for the removal of wastewater ammonium and nitrate nitrogens. To this end, the author tracked adsorption variations as seen with the adsorption removal of wastewater ammonium and nitrate nitrogens. As a result, it was indicated that the maximum adsorption of zeolite acting on the adsorption removal of ammonium nitrogen would reach 120mg/g (weight of ammonium nitrogen divided by that of zeolite), and that Langmuir adsorption isotherm explained the adsorption of ammonium and nitrate nitrogens better than Freundlich adsorption isotherm. This means that zeolite makes ion exchanges with adsorbate for unilayer adsorption. It was also indicated that the removal efficiency of ammonium nitrogen with varying pH would be higher in the order of pH7 > pH5 > pH9 > pH3.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1043-1051
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• 2005

In this stduy, adsorption and transport characteristics of Fe in the soil were investigated using convection-dispersion local equilibrium sorption model and two-site non-equilibrium sorption model. In batch experiments with different Fe concentration, characteristics of Fe adsorption was investigated using Freundlich and linear isotherm. Column experiments with different flow rate, organic matter content md Fe concentration were also carried out. We measured Fe concentrations in injection-liquid and in effluent, and then applied them to CXTFIT program. As a result of column experiments, some parameters(D, R, ${\beta}$, ${\omega}$) used in two-site non-equilibrium adsorption model were obtained. Characteristics of Fe transport were analyzed using the parameters(D, R, ${\beta}$, ${\omega}$) obtained from the CXTFIT program, Consequently, characteristics of Fe transport in the soil were predicted through two-site non-equilibrium adsorption model.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.486-491
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• 2014

In this paper, the adsorption behavior and kinetic characteristics of cibacron brilliant red 3B-A from aqueous solution using granular activated carbon were investigated. The effect of various parameters such as adsorbent dose, pH, initial concentration, contact time and temperature on the adsorption system were studied. Base on the estimated Langmuir constant ($R_L$) and Freundlich constant (1/n), This process could be employed as effective treatment method. From the Temkin constant (B) and Dubinin-Radushkevich constant (E), This adsorption process is physical adsorption. From kinetic experiments, the adsorption process followed the pseudo second order model with good correlation. Base on the Gibbs free energy and enthalpy, the adsorption of cibacron brilliant red 3B-A onto granular activated carbon was physisorption and endothermic in nature.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.624-634
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• 2020

The ability of natural and modified clay to adsorb phenol was studied. The clay samples were analyzed by different technical instruments, such as X-ray fluorescence (XRF), X-ray diffraction (XRD) and FT-IR spectroscopy. Surface area, pore volume and average pore diameter were also determined using B.E.T method. Up to 73 and 99% of phenol was successfully adsorbed by natural and activated clay, respectively, from the aqueous solution. The experiments carried out show that the time required to reach the equilibrium of phenol adsorption on all the samples is very close to 60 min. The amount of phenol adsorbed shows a declining trend with higher pH as well as with lower pH, with most extreme elimination of phenol at pH 4. The adsorption of phenol increases proportionally with the initial phenol concentration. The maximum adsorption capacity at 25 ℃ and pH 4 was 29.661 mg/g for modified clay (NaMt). However, the effect of temperature on phenol adsorption was not significant. The simple modification causes the formation of smaller pores in the solid particles, resulting in a higher surface area of NaMt. The equilibrium results in aqueous systems were well fitted by the Freundlich isotherm equation (R² > 0.98). Kinetic studies showed that the adsorption process is best described by the pseudo-second-order kinetics (R² > 0.99). The adsorption of phenol on natural and modified clay was spontaneous and exothermal.

• Journal of Korean Society on Water Environment
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• v.24 no.3
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• pp.311-316
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• 2008

This study aimed to obtain equilibrium concentration on adsorption removal of ammonia nitrogen by activated carbon, to express the adsorption characteristics following Freundlich isotherm and also, based on the value obtained, to investigate the relationship between physical characteristics of activated carbon and dynamics of ammonia nitrogen removal by obtaining rate constant and effective pore diffusivity. The results summarized from this study are as follows. It was noted that powdered activated carbon showed better adsorption ability than granular activated carbon. The value of constant (f) of Freundlich isotherm of powered activated carbon was $4.6{\times}10^{-8}$ which is bigger than that of granular activated carbon. The adsorption rate constant on ammonia nitrogen of powered activated carbon with high porosity and low effective diameter was highest as 0.416 hr-1 and the effective pore diffusivity ($D_e$) was lowest as $1.17{\times}10^{-6}cm^2/hr$, and the value of ammonia nitrogen adsorption rate constant of granular activated carbon was $0.149{\sim}0.195hr^{-1}$. It was revealed that, with the same amount of dosage, the adsorptive power of activated carbon with lower effective diameter and bigger porosity was better and its rate constant was also high. With a little adsorbent dosage of 2 g, there was no difference removal ability of ammonia nitrogen as change of adsorption properties.

• Journal of Korean Society on Water Environment
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• v.26 no.3
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• pp.491-496
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• 2010

This study aimed to obtain equilibrium concentration on adsorption removal of phosphorus by activated carbon, to express the adsorption characteristics following Freundlich isotherm and also, based on the value obtained, to investigate the relationship between physical properties of activated carbon and dynamics of phosphorus removal by obtaining rate constant and effective pore diffusivity. The results summarized from this study are as follows. Phosphorus adsorption equilibrium reaching time of powdered activated carbon was reduced as the dosage of activated carbon increases, while granular activated carbon despite increased dosage did not have influence on adsorption equilibrium reaching times of phosphorus as well, taking more than 10 hours. It was also noted that powdered activated carbon showed better adsorption ability than granular activated carbon. The value of constant (f) of Freundlich isotherm of powered activated carbon on phosphorus was 4.26 which is bigger than those of granular activated carbon. The adsorption rate constant on phosphorus of powered activated carbon with low effective diameter and iodine number was highest as $8.888hr^{-1}$ and the effective pore diffusivity ($D_e$) was lowest as $2.45{\times}10^{-5}cm^2/hr$, and the value of phosphorus adsorption rate constant of granular activated carbon was $0.174{\sim}0.372hr^{-1}$, It was revealed that, with the same amount of dosage, the adsorptive power of activated carbon with lower effective diameter was better and its rate constant was also high.

• Journal of Environmental Science International
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• v.20 no.2
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• pp.185-197
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• 2011

Sorption of chlorinated pesticides such as 2,4-dichlorophenoxyacetic acid (2,4-D) and atrazine onto natural clays (montmorillonite and zeolite) modified with cationic surfactant, hexadecyltrimethyl-ammonium (HDTMA) and a natural soil was investigated using batch adsorbers. The clays were transformed from hydrophilic to hydrophobic by the cation exchange between clay surface and HDTMA up to 100% of the cation exchange capacity (CEC). Physicochemical characteristics of the sorbents such as pH, PZC (point of zero charge), organic carbon content ($f_{oc}$), fourier transform infrared spectroscopy (FT-IR), differential thermogravimetric analysis (DTGA) and X-ray diffraction (XRD) were analyzed. Sorption isotherm models such as Freundlich and Langmuir were fitted to the experimental data, resulting Langmuir model ($R^2$ > 0.986) was fitted better than Freundlich model ($R^2$ > 0.973). Sorption capacity ($Q^0$) for 2,4-D and atrazine was in the order of HDTMA-montmorillonite > HDTMA-zeolite > natural soil corresponding to the increase in organic carbon content ($f_{oc}$). The sorption of the pesticides was also affected by pH. The sorption of 2,4-D decreased with the increase in pH, whereas that of atrazine was not changed. This indicated that the sorption capacity ($Q^0$) of 2,4-D and atrazine was not affected by the solution pH because they exist as anionic (deprotonated) forms at pH above pKa. The results indicate that organoclay has a promising potential to reduce chlorinated pesticides in the effluent from golf courses.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.2
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• pp.25-33
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• 1984

The effect of particle size on adsorption of trihalomethane have been studied. Using mean particle sizes ranging from 0.73 to 2.03 mm, physical properties of carbon and trihalomethane adsorption characteristics have been investigated experimentally. With increasing particle size specific surface area and pore volume decreased, and the mean pore radius increased significantly. Large pores were dominant in large particles, while small particles were composed of small pores. Isotherm studies were conducted using static bottle point technique and the results were well described by the Freundlich isotherm equations. The adsorption capacity increased significantly with decreased particle size. Additionally micro-column tests were carried out, and the results were compared with the model simulation. From the micro-column studies it was found out that the film transfer coefficient were almost constant, and the differences in the trihalomethane removal efficiency was mainly due to the differences in the adsorption capacity of the particles of different size.