• Korean Journal of Environmental Agriculture
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• v.35 no.1
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• pp.24-31
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• 2016

BACKGROUND: Heavy metal adsorption not only depends on rapid cooling slag(RCS) characteristics but also on the nature of the metals involved and on their competitive behavior for RCS adsorption sites. The goal of this study was to investigate the competitive absorption characteristics of Cu, Cd and Zn in single- and multi-metal forms by RCS.METHODS AND RESULTS: Both single- and multi-metal adsorption experiments were conducted to determine the adsorption characteristics of RCS for the heavy metals. Adsorption behaviors of the heavy metals by RCS were evaluated using both the Freundlich and Langmuir adsorption isotherm equations. The maximum adsorption capacities of metals by RCS were in the order of Cu(16.6 mg/g) > Cd(8.1 mg/g) > Zn(6.2 mg/g) in the single-metal adsorption isotherm and Cu(14.5 mg/g) >> Zn(1.3 mg/g) > Cd(0.6 mg/g) in the multi-metal adsorption isotherm. Based on data obtained from Freundlich and Langmuir adsorption models and three-dimensional simulation, multi-metal adsorption behaviors differed from single- metal adsorption due to competition. Cadmium and Zn were easily exchanged and substituted by Cu during multi-metal adsorption.CONCLUSION: Results from adsorption experiments indicate that competitive adsorption among metals increases the mobility of these metals.

• Korean Chemical Engineering Research
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• v.57 no.2
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• pp.210-218
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• 2019

Batch experiment studies were carried out on the adsorption of the major tar compound, 2-picoline, derived from the plant cell cultures of Taxus chinensis, using Sylopute while varying parameters such as initial 2-picoline concentration, contact time and adsorption temperature. The experimental data were fitted to the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. Comparison of results revealed that the Langmuir isotherm model could account for the adsorption isotherm data with the highest accuracy among the four isotherm models considered. From the analysis of adsorption isotherms, it was found that adsorption capacity decreased with increasing temperature and the adsorption of 2-picoline onto Sylopute was favorable. The kinetic data were well described by the pseudo-second-order kinetic model, while intraparticle diffusion and boundary layer diffusion did not play a dominated role in 2-picoline adsorption according to the intraparticle diffusion model. Thermodynamic parameters revealed the exothermic, irreversible and non-spontaneous nature of adsorption. The isosteric heat of adsorption decreased as surface loading ($q_e$) increased, indicating a heterogeneous surface.

• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.632-638
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• 2014

Batch adsorption studies including equilibrium, kinetics and thermodynamic parameters for the adsorption of new fuchsin dye using granular activated carbon were investigated with varying the operating variables such as initial concentration, contact time and temperature. Equilibrium adsorption data were fitted into Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherms. Adsorption equilibrium was mostly well described by Langmuir Isotherm. From the estimated separation factor of Langmuir ($R_L$ = 0.023), and Freundlich (1/n = 0.198), this process could be employed as an effective treatment for the adsorption of new fuchsin dye. Also based on the adsorption energy (E = 0.002 kJ/mol) from Dubinin-Radushkevich isotherm and the adsorption heat constant (B = 1.920 J/mol) from Temkin isotherm, this adsorption is physical adsorption. From kinetic experiments, the adsorption reaction processes were confirmed following the pseudo second order model with good correlation. The intraparticle diffusion was a rate controlling step. Thermodynamic parameters including changes of free energy, enthalpy, and entropy were also calculated to predict the nature of adsorption. The change of enthalpy (92.49 kJ/mol) and activation energy (11.79 kJ/mol) indicated the endothermic nature of adsorption processes. The change of entropy (313.7 J/mol K) showed an increasing disorder in the adsorption process. The change of free energy found that the spontaneity of process increased with increasing the adsorption temperature.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.2
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• pp.111-126
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• 1992

Silica sorption isotherm belonged to the C-type with weak L-type characteristics according to the classification system of adsorption isotherm. Silica sorption isothem fitted well to the Freundlich and Tempkin equation but not to the Langmuir equation. The color interference probably due to $Fe^{2+}$ during spectrometric silca determination by Molybdenum-blue method affected the sorption isotherm in reduced soils or low pH. Four parameters such as the intercept of Freundlich equation, the slope of Tempkin equation, the "Silica reactivity", and the "C-type slope", where the last two parameters were termed in the current study, were examined to assess treatment effects on silica sorption. Among them the "C-type slope" was found out to be the best parameter. The C-type isotherms showed the same high correlation coefficient as Freundlich and Tempkin equation when regressed to the sorption isothem. Plotting the C-type slope on a logarithmic scale vs. the pH showed high linearity. Using the "C-type slope" as a perameter, the pH and soil type affected the silica sorption while the effect of redox condtion was not significant. All Fe and Al extracted by the various reagents, and OM were highly correlated to silica sorption. Among them $Fe_d$ was identified as the highest influencing soil property. Since there is no equivalent reliable method to discriminate the forms of the soil Al-oxides their likely importance remains unclear.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.190-197
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• 2019

The adsorption of methyl green dye using an activated carbon from an aqueous solution was investigated. Adsorption experiments were carried out as a function of the adsorbent dose, initial concentration, contact time and temperature. The Langmuir isotherm model showed a good fit to the equilibrium adsorption data. Based on the estimated Langmuir separation factor, ($R_L=0.02{\sim}0.106$), this process could be employed as the effective treatment (0 < $R_L$ < 1). It was found that the adsorption was a physical process with the adsorption energy (E) value range between 316.869 and 340.049 J/mol obtained using Dubinin-Radushkevich equation. The isothermal saturation capacity obtained from brunauer emmett teller (BET) model increased with increasing the temperature. The kinetics of adsorption followed a pseudo second order model. The free energy and enthalphy values of -5.421~-7.889 and 31.915 kJ/mol, respectively indicated that the adsorption process follows spontaneous endothermic reaction. The isosteric heat of adsorption increased with the increase of equilibrium adsorption amounts, and the total interaction of the adsorbent - adsorbate increased as the surface coverage increased.

• Journal of the Korean Chemical Society
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• v.61 no.5
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• pp.238-243
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• 2017

In this study, water treatment sludge carbonized with $400^{\circ}C$ was tested as an adsorbent for the removal of Pb and Cd in water. The carbonized sludge was characterized by thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray fluorescence spectrometry (XRF), and surface area analysis. Carbonized sludge exhibited much higher specific surface area and total pore volume than water treatment sludge itself. In batch-type adsorption process, carbonized sludge represented better adsorption performance for Pb than Cd, achieving 90~98% at the concentrations conducted in the experiments. Equilibrium data of adsorption were analyzed using the Freundlich and Langmuir isotherm models. It was seen that both Freundlich and Langmuir isotherms have correlation coefficient $R^2$ value larger than 0.95. The results of studies indicated that carbonized water treatment sludge by heat treatment could be used as an efficient adsorbent for the removal of Pb and Cd from water.

• KSBB Journal
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• v.11 no.2
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• pp.173-180
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• 1996

The contamination of the environment by heavy metals results in a serious public health problem due to the toxicity of those pollutants even at low concentrations. Microorganisms may be used to remediate wastewaters contamlialtd with heavy metals. The waste S. cerevisiae is an inexpensive readily available source of biomass for bioremediation of wastewater. S. cerevisiae was investigated for their ability to absorb Pb. The crushed biomass of S. cerevisiae exhibited higher Pb uptake capacity than the living S. cerevisiae and the sterilized S. cerevisiae. At the same metal concentration, metal uptake per unit concentration or adsorbent decreased when the biomass concentration rises. The order of the biosorption capacity of the living S. cerevisiae was Pb>Cu>Cd=Co>Cr. When S. cerevisiae was pretreated with 0.1 M NaOH, Pb uptake was increased by 150 percent and 0.1 M HC1, 0.1 M $H_2S_O4$ solutions were efficient in the desorption of Pb. The sorption equilibrium of Pb ions can be described by the Freundlich and Langmuir models.

• Clean Technology
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• v.26 no.3
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• pp.186-195
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• 2020

The isothermal adsorption, dynamic, and thermodynamic parameters of Acid black (AB) and Quinoline yellow (QY) adsorption by activated carbon were investigated using the initial concentration, contact time, temperature, and pH of the dyes as adsorption parameters. The adsorption equilibrium data fits the Freundlich isothermal adsorption model, and the calculated Freundlich separation factor values found that activated carbon can effectively remove AB and QY. Comparing the kinetic data showed that the pseudo second order model was within 10% error in the adsorption process. The intraparticle diffusion equation results were divided into two straight lines. Since the slope of the intraparticle diffusion line was smaller than the slope of the boundary layer diffusion line, it was confirmed that intraparticle diffusion was the rate-controlling step. The thermodynamic experiments indicated that the activation energies of AB and QY were 19.87 kJ mol^-1 and 14.17 kJ mol^-1, which corresponded with the physical adsorption process (5 ~ 40 kJ mol^-1). The adsorption reaction was spontaneous because the free energy change in the adsorption of AB and QY by activated carbon was negative from 298 to 318 K. As the temperature increased, the free energy value decreased resulting in higher spontaneity. Adsorption of AB and QY by activated carbon showed the highest adsorption removal rate at pH 3 due to the effect of anions generated by dissociation. The adsorption mechanism was electrostatic attraction.

• Journal of Life Science
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• v.8 no.2
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• pp.208-215
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• 1998

It was investigated the biosorption performances of copper by the immobilized biomass of nonliving marine brown alge h. fusiformis by each of the Ca-alginate method(Ca-ALG), Ba-alginate method(Ba-ALG), polyethylene glycol method(PEG), and carrageenan method (CARR). The copper removal performance increased but the copper uptake decreased as the biomass amount was increased. However, the copper uptake by the immobilized biomass increased with increasing initial copper concentration. The copper uptake by the immobilized biomass of the immobilization method decreased in the following sequence; Ca-ALG>Ba-ALG>PEG>CARR among the immoblization emthods. The copper uptake by the immobilized biomass followed the Langmuir isotherm better than the Freundlich isotherm.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1193-1203
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• 2000

In this study, in order to remove Cd(II) from aqueous solutions, strongly acidic cation exchange resin(SK1B) by Diaion Co. was employed as an adsorbent. Experiments were mainly performed in two parts at room temperature($25{\pm}5^{\circ}C$) : batch tests and adsorption kinetics tests. In batch tests adsorption equilibrium time, pH effects, temperature effects, several adsorption isotherms, and finally desorption tests were examined. In differential bed tests, an optimum flow rate and an overall adsorption rate were obtained. In the batch experiment, adsorption capability increased with pH and became constant above pH 6 and adsorption quantity increased with temperature. Batch experimental data found that Freundlich and Sips adsorption isotherms were more favorable than Langmuir adsorption isotherm over the range of concentration (5~15ppm). The desorbent used in the desorption test was hydrochloric acid solution with different concentrations(0.01~2N). The degree of regeneration increased with concentration of desorbent and decreased slightly with the number of regeneration. In the continuous flow process using a differential bed reactor, the optimum flow rate was $564m{\ell}/min$ above which the film diffusion resistance was minimized. The overall adsorption rate for the removal of Cd(II) by cation exchange resin was found as follows ; $r=1.3785C_{fc}^{1.2421}-2.0907{\times}10^{0.0746C_i}\;q_e^{0.0121C_i-0.0301}$