• Advances in environmental research
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• v.2 no.3
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• pp.245-260
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• 2013

Biosorption represents a technological innovation as well as a cost effective excellent remediation technology for cleaning up radionuclides from aqueous environment. In the present study, a bacteria strain FB12 with high adsorption rate of uranium ion was isolated from the vicinity of the nuclear power plant. It was tentatively identified as Bacillus sp.FB12 according to the 16S rDNA sequencing. Efforts were made to further improve the adsorption rate and genetic stability by UV irradiation and UV-LiCl cooperative mutagenesis. The improved strain named Bacillus sp.UV32 obtains excellent genetic stability and a high adsorption rate of 95.9%. The adsorption of uranium U (VI) by Bacillus sp.UV32 from aqueous solution was examined as a function of metal ion concentration, cell concentration, adsorption time, pH, temperature, and the presence of some foreign ions. The adsorption process of U (VI) was found to follow the pseudo-second-order kinetic equation. The adsorption isotherm study indicated that it preferably followed the Langmuir adsorption isotherm. The thermodynamic parameters values calculated clearly indicated that the adsorption process was feasible, spontaneous and endothermic in nature. These properties show that Bacillus sp.UV32 has potential application in the removal of uranium (VI) from the radioactive wastewater.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.78-82
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• 2003

Development of hematite-coated sand was evaluated for the application of the PRB (permeable reactive barrier) in the arsenic-contaminated subsurface of the metal mining areas. The removal efficiency of As(III) and As(V), the effect of anion competition and the capability of arsenic removal in the flow system were investigated through the experiments of adsorption isotherm, arsenic removal kinetics against anion competition and column removal. Hematite-coated sand followed a linear adsorption isotherm with high adsorption capacity at low level concentrations of arsenic (< 1.0 mg/l). When As(III) and As(V) underwent adsorption reactions in the presence of anions (sulfate, nitrate and bicarbonate), sulfate caused strong inhibition of arsenic removal, and bicarbonate and nitrate caused weak inhibition due to specific and nonspecific adsorption onto hematite, respectively. In the column experiments, high content of hematite-coated sand enhance the arsenic removal, but the amount of the arsenic removal decreased due to the higher affinity of As(V) than As(III) and reduced adsorption kinetics in the flow system, Therefore, the amount of hematite-coated sand, the adsorption affinity of arsenic species and removal kinetics determined the removal efficiency of arsenic in the flow system. arsenic, hematite-coated sand, permeable reactive barrier, anion competition, adsorption.

• Journal of Environmental Science International
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• v.30 no.9
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• pp.719-726
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• 2021

In this study, zeolitic materials were synthesized from Jeju Volcanic Rocks (JVR) using a fusion/hydrothermal method at NaOH/JVR ratios of 0.6 and 1.2. The crystallinities of the zeolitic materials at NaOH/JVR ratios of 0.6 and 1.2 were 25.5% and 59.0%, respectively. It was confirmed through the SEM image that the zeolitic materials covered the zeolite particle with a cube-shaped crystals. The Co ions adsorption by the zeolitic materials were to reach the adsorption equilibrium at 120 min. It could be better simulated in the pseudo-second order adsorption kinetic equation than in the pseudo-first order adsorption kinetic equation. The adsorption capacities (q_m) of Co ions could be to estimate Langmuir isotherm better than Freundlich isotherm. The maximum adsorption capacities (q_m) at NaOH/JVR ratios of 0.6 and 1.2 were 55.3 mg/g and 68.7 mg/g, respectively. It was found that there was a high correlation between the crystallinity of zeolitic materials and the adsorption capacity of Co ions adsorption.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.115-119
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• 2010

Neutral red5 (BR 5) adsorption from aqueous solution was investigated. New solid adsorbent was prepared from paper sludge incinerated at $250^{\circ}C$ during 2 hours. Experiments were carried out, in batch system, to remove RB5 dye from the synthetic waste water. Maximum adsorption of 374.98 mg/g at pH 5, at room temperature and contact time of 80 min was obtained. The Langmuir and Freundlich adsorption models were applied to interpret the equilibrium isotherm. The Freundlich isotherm fits quite well with the experimental data (with highly regression coefficient $R^2$). The incinerated sludge solid samples untreated and treated with BR5 dye were characterized by FT-IR spectrophotometer.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.1
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• pp.113-119
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• 2009

The feasibility of using cork oak bark for phosphorus removal from wastewater was evaluated in this study. Recently, development of more cost-effective media while maintaining high efficiency in pollutants removal has received concern. Barks have a negative surface charge and, hence, tend to show a high affinity to bind cations, and they need to undergo chemical modification to increase their adsorption capacity of anions. Bark was hydrolyzed by HCl solution and it received modification using an aqueous solution of high molecular weight polyethylenimine(PEI). Surface modification with HCl and PEI resulted in a decrease of specific surface area of the bark from $1.932 m^2/g$ to $1.094 m^2/g$. The adsorption experiments were carried out in batch tests and the data were fitted to the Langmuir isotherm and Freundlich isotherm equations. Phosphate removal rate was higher at the lower solution pH possibly due to the form of phosphate ion in solution. For the initial phosphate concentration of 10 mg/L, maximum adsorption was 20.88 mg P/g at pH 3 and 12.02 mg P/g at pH 5. Mechanism of phosphorus sorption onto the HCl-PEI bark was examined through FT-IR spectrometer. Ion exchange between $NH^+$ and $H_2PO_4{^-}$ appeared to be a key mechanism of phosphate adsorption onto the HCl-PEI bark surface.

• Journal of the Korean Electrochemical Society
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• v.10 no.3
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• pp.219-228
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• 2007

The phase-shift method and correlation constants, i.e., the electrochemical impedance spectroscopy (EIS) techniques for studying linear relationships between the behaviors (${\varphi}\;vs.\;E$) of the phase shift ($0^{\circ}{\leq}-{\varphi}{\leq}90^{\circ}$) for the optimum intermediate frequency and those (${\theta}\;vs.\;E$) of the fractional surface coverage ($1{\geq}{\theta}{\geq}0$), have been proposed and verified to determine the Langmuir, Frumkin, and Temkin adsorption isotherms (${\theta}\;vs.\;E$) of H for the cathodic $H_2$ evolution reaction (HER) at noble and transition-metal/aqueous solution interfaces. At the Pt/0.1 MKOH aqueous solution interface, the Langmuir, Frumkin, and Temkin adsorption isotherms (${\theta}\;vs.\;E$), equilibrium constants ($K=5.6{\times}10^{-10}\;mol^{-1}\;at\;0{\leq}{\theta}<0.81$, $K=5.6{\times}10^{-9}{\exp}(-4.6{\theta})\;mol^{-1}\;at\;0.2<{\theta}<0.8$, and $K=5.6{\times}10^{-10}{\exp}(-12{\theta})\;mol^{-1}\;at\;0.919<{\theta}{\leq}1$, interaction parameters (g = 4.6 for the Temkin and g = 12 for the Frumkin adsorption isotherm), rates of change of the standard free energy ($r=11.4\;kJ\;mol^{-1}$ for g=4.6 and $r=29.8\;kJ\;mol^{-1}$ for g=12), and standard free energies (${\Delta}G_{ads}^0=52.8\;kJ\;mol^{-1}\;at\;0{\leq}{\theta}<0.81,\;49.4<{\Delta}G_{\theta}^0<56.2\;kJ\;mol^{-1}\;at\;0.2<{\theta}<0.8$ and $80.1<{\Delta}_{\theta}^0{\leq}82.5\;kJ\;mol^{-1}\;at\;0.919<{\theta}{\leq}1$) of OH for the anodic $O_2$ evolution reaction (OER) are also determined using the phase-shift method and correlation constants. The adsorption of OH transits from the Langmuir to the Frumkin adsorption isotherm (${\theta}\;vs.E$), and vice versa, depending on the electrode potential (E) or the fractional surface coverage (${\theta}$). At the intermediate values of ${\theta}$, i.e., $0.2<{\theta}<0.8$, the Temkin adsorption isotherm (${\theta}\;vs.\;E$) correlating with the Langmuir or the Frumkin adsorption isotherm (${\theta}\;vs.\;E$), and vice versa, is readily determined using the correlation constants. The phase-shift method and correlation constants are accurate and reliable techniques to determine the adsorption isotherms and related electrode kinetic and thermodynamic parameters. They are useful and effective ways to study the adsorptions of intermediates (H, OH) for the sequential reactions (HER, OER) at the interfaces.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.10-16
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• 2020

Computational simulations of adsorption columns were carried out to investigate the removal characteristics of VOCs from a laundry shop. n-Decane was selected as the representative component among the VOCs emitted, and the activity of the adsorbents, such as activated carbon, was evaluated using commercial CFD code. The mathematical framework was composed of continuity and Navier-stokes equations, and the simulation was performed using the Matlab program. The adsorption isotherms of LDF, Freundlich, and Langmuir were evaluated, and the adsorption amount of the adsorption isotherms with the adsorption parameter was compared. The simulation was carried out using a particle porosity, dispersion coefficient, particle density, bed diameter, and bed length of 0.79, 42.4 ㎠/min, 485 g/L, 2.0 cm, and 2.5 cm, respectively. The effect of the gas velocity, dispersion coefficient, and voidage on the adsorption amount was compared in the Langmuir adsorption isotherm. The simulation was carried out in the velocity range of 50 to 200 cm/min, dispersion coefficient range of 100 to 400 ㎠/min, and particle porosity range of 0.66 to 0.79. The simulation results of activated carbon with benzene coincided with the Langmuir isotherm. Three types of adsorption isotherm were compared under similar conditions, and the simulation results showed the efficient adsorption condition for hydrocarbons.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.290-291
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• 2001

흡착입자간의 상호작용이 존재하는 경우 특히 최근접상호작용(nearest neighbour interaction)만이 고려된 경우의 흡착등온식(adsorption isotherm)을 구한다. 분배함수의 계산에는 Kramers와 Wannier에 의한 행열식 방법이 유용하게 사용된다.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2753-2759
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• 2013

The aim of the present study is to explore the possibility of utilizing fly ash and loess, as alternative to activated carbon, for the adsorption of diazinon in water. Batch adsorption experiment was performed to evaluate the influences of various factors like initial concentration, contact time and temperature on the adsorption of diazinon. The adsorption data shows that fly ash is not effective for the adsorption of diazinon. The equilibrium data for both activated carbon and loess were fitted well to the Freundlich isotherm model. The pseudo-second-order kinetic model appeared to be the better-fitting model because it has higher $R^2$ compared to the pseudo-first-order kinetic model. The thermodynamic parameters such as free energy (${\Delta}G$), the enthalpy (${\Delta}H$) and the entropy (${\Delta}S$) were calculated. Contrary to loess, the ${\Delta}G$ values of activated carbon were negative at the studied temperatures. It indicates that the adsorption of diazinon by activated carbon is a favorable and spontaneous process. The positive ${\Delta}H$ values of activated carbon and loess suggest that the diazinon adsorption process is endothermic in nature. In addition, the positive ${\Delta}S$ values show that increased randomness occurs at the solid/solution surface during the adsorption of diazinon.

• Advances in environmental research
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• v.4 no.3
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• pp.197-210
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• 2015

Hexavalent chromium [Cr (VI)] adsorption on lateritic soil and lateritic soil blended with black cotton (BC) soil, marine clay and bentonite clay were studied in the laboratory using batch adsorption techniques. In the present investigation the natural laterite soil was blended with 10%, 20% and 30% BC soil, marine clay and bentonite clay separately. The interactions on test soils have been studied with respect to the linear, Freundlich and Langmuir isotherms. The linear isotherm parameter, Freundlich and Langmuir isotherm parameters were determined from the batch adsorption tests. The adsorption of Cr (VI) on natural laterite soil and blended laterite soil was determined using double beam spectrophotometer. The distribution coefficients obtained were 1.251, 1.359 and 2.622 L/kg for lateritic soil blended with 10%, 20% and 30% BC soil; 5.396, 12.973 and 48.641 L/kg for lateritic soil blended with marine clay and 5.093, 8.148 and 12.179 L/kg for lateritic soil blended with bentonite clay respectively. The experimental data fitted well to the Langmuir model as observed from the higher value of correlation coefficient. Soil pH and iron content in soil(s) has greater influence on Cr (VI) adsorption. From the study it is concluded that laterite soil can be blended with clayey soils for removing Cr (VI) by adsorption.