• Resources Recycling
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• v.8 no.1
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• pp.37-43
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• 1999

Studies have been conducted for the purpose of using manganese nodule and residue remained after extracting valuable metals [mm it as the adsorbent of cadmium wastewater. The study observed the adsorption percentage according to initial cadmium concentration and interpreted each adsorption systems by applying the Freundlich, Langmuir, and Temkin isotherms. The adsorption amounts increased as the initial concentration at cadmium ion increased, whereas the adsorption percentage decreased. Linearity was shown when applied to the Freundlich and Langmuir isotherms. The k value which evaluates the adsorption capacity of adsorbent in Freundlich isotherm, turned out to be 11.72, the highest in case of manganese nodule. The Xm value, the maximum adsorption amount of the adsorbate that adsorbs as a monolayer in Langmuir isotherm of manganese nodule, was estimated as 0.16, representing higher value compared with those of leached residue, leached residue-raw manganese nodule mixture, and activated carbon.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.180-183
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• 2001

오염물 이동에 영향을 미치는 지연계수는 용질과 시료의 흡착특성을 나타낸다. 흡착특성을 표현하는 데에는 Freundlich등온식, Langmuir등온식 또는 선형등온식등을 사용할 수 있는 데, 본 연구에서는 상관계수를 이용하여 각등온식의 적용성을 평가하고 용질이동 수치해 석을 하여 농도가 10ppm 이하로 낮을 경우의 용질이동정도를 상호 비교하였다. 아연, 크롬, 납에 대한 등온식의 상관계수에 따른 적용성 평가결과 Freundlich 등온식이 보편적으로 적용 가능한 것으로 나타났고, 수치해석 결과 농도가 10ppm 이하일 경우는 용질이동성이 동일하게 나타났다.

• Korean Journal of Environmental Agriculture
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• v.33 no.3
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• pp.169-177
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• 2014

BACKGROUND: The ferronickel and rapid cooling slags used in present study are industrial wastes derived from a steel factory in Korea. These slags are used as almost road construction materials after magnetic separation. However, the use of slag to remove phosphorus from wastewater is still a relatively less explored. The objective of this work was to evaluate the feasibility of ferronickel slag (FNS) and rapid cooling slag (RCS) as sorbents for phosphorus removal in wastewater. METHODS AND RESULTS: Adsorption experiments were conducted to determine the adsorption characteristics of the FNS and RCS for the phosphorus. Adsorption behaviour of the phosphorus by the FNS and RCS was evaluated using both the Freundlich and Langmuir adsorption isotherm equations. FNS and RCS were divided into two sizes as effective sizes. Effective sizes of FNS and RCS were 0.5 and 2.5 mm, respectively. The adsorption capacities (K) of the phosphorus by the FNS and RCS were in the order of RCS 0.5 (0.5105) > RCS 2.5 (0.3572) ${\gg}$ FNS 2.5 (0.0545) ${\fallingdotseq}$ FNS 0.5 (0.0400) based on Freundlich adsorption isotherm. The maximum adsorption capacities (a; mg/kg) of the phosphorus determined by the Langmuir isotherms were in the order of RCS 0.5 (3,582 mg/kg) > RCS 2.5 (2,983 mg/kg) > FNS 0.5 (320 mg/kg) ${\fallingdotseq}$ FNS 2.5 (187 mg/kg). RCS 0.5 represented the best sorbent for the adsorption of phosphorus. In the experiment, the Langmuir model showed better fit with our data than the Freundlich model. CONCLUSION: This study indicate that the use of RCS in constructed wetlands or filter beds is a promising solution for phosphorus removal via adsorption and precipitation mechanisms.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.458-465
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• 2020

Isotherms, kinetics and thermodynamic properties for adsorption of acid fuchsin (AF) dye by activated carbon were carried out using variables such as dose of adsorbent, pH, initial concentration and contact time and temperature. The effect of pH on adsorption of AF showed a bathtub with high adsorption percentage in acidic (pH 8). Isothermal adsorption data were fitted to the Freundlich, Langmuir, and Dubinin-Radushkevich isotherm models. Freundlich isothem model showed the highest agreement and confirmed that the adsorption mechanism was multilayer adsorption. It was found that adsorption capacity increased with increasing temperature. Freundlich's separation factor showed that this adsorption process was an favorable treatment process. Estimated adsorption energy by Dubinin-Radushkevich isotherm model indicated that the adsorption of AF by activated carbon is a physical adsorption. Adsorption kinetics was found to follow the pseudo-second-order kinetic model. Surface diffusion at adsorption site was evaluated as a rate controlling step by the intraparticle diffusion model. Thermodynamic parameters such as activation energy, Gibbs free energy, enthalpy entropy and isosteric heat of adsorption were investigated. The activation energy and enthalpy change of the adsorption process were 21.19 kJ / mol and 23.05 kJ / mol, respectively. Gibbs free energy was found that the adsorption reaction became more spontaneously with increasing temperature. Positive entropy was indicated that this process was irreversible. The isosteric heat of adsorption was indicated physical adsorption in nature.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1213-1223
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• 2000

The adsorption characteristics of phenol has been studied by using CDQ (Cokes Drying Quenching) dust as an adsorbent. The adsorption capacity of CDQ dust was shown to be 42% about removal for 300 ppm phenol solution at the equilibrium adsorption time of 60 min. Removal percentage of phenol increased as the initial phenol concentration was raised in the experimental conditions and the adsorption behavior was explained well by Freundlich adsorption isotherm. Kinetic study showed that the adsorption followed 1st, 1.5th, and 2nd-order rate equation in the sequence as the adsorption time passed. Since the adsorption amount of phenol was increased as the adsorption temperature was raised, the adsorption was thought to be endothermic, and several thermodynamic parameters have been calculated based upon experimental data. Adsorbed amount of phenol on CDQ dust changed little according to the variation in the solution pH except for the slight decrease under the strong alkaline condition.

• Journal of Industrial Technology
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• v.27 no.A
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• pp.203-209
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• 2007

본 연구는 목재로서 활용가치가 적은 수피(bark)를 활용하여 수질오염물질을 제거할 수 있는 여과 시스템에 대한 기초연구로서 소나무의 일종인 loblolly pine(Pinus taeda L.) 수피의 인 ($PO_4-P$) 흡착특성을 연구하였다. 실험에 사용된 수피는 입상형태로서 polyallylamine hydrochloride로 전처리하여 회분식 등온 흡착실험을 수행하였다. 회분식 등온흡착실험은 수용액 pH 3~pH 8범위에서, 인의 농도별(10, 20, 30, 40 mg/L)로 수행하였다. pH 5에서 가장 높은 인 제거 효율을 나타냈으며, 수용액의 pH는 실험 후 pH 3으로 감소하였다. 이러한 감소는 수피에 의한 phosphate의 흡착이 Lewis acid-base 반응으로서 이 과정에서 $H^+$의 방출로 인하여 나타난 현상인 것으로 여겨지며, 주된 반응 메카니즘은 더 연구할 필요성이 있다. 인 흡착은 초기에 빠른 속도로 진행되었으며 대략 200분 이후에 평형에 도달하였고, 시간이 지날수록 흡착양이 증가하는 경향을 보였다. 인의 흡착특성 결과는 Langmuir 등온흡착식과 Freundlich 등온흡착식으로 설명될 수 있으며, 등온흡착식 적용결과, 흡착제에 대한 최대 흡착능은 7.14 mg/g 이며 다른 흡착제와 비교하여 더 높았다. 실험결과와 모델에 의한 흡착능을 비교하고자 pseudo second-order model을 적용하여 흡착 동역학 상수를 구하였다. 또한 EDXA분석으로 회분식 흡착실험 후 수피와 인이 결합되어있는 것을 확인할 수 있었다.

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.127-134
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• 2020

The adsorption characteristics of the major tar compound, acenaphthene, derived from Taxus chinensis by the commercial adsorbent Sylopute were investigated using different parameters such as initial acenaphthene concentration, adsorption temperature, and contact time. Out of Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models, adsorption data were best described by Langmuir isotherm. The adsorption kinetics was evaluated by pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The pseudo-second-order model was found to explain the adsorption kinetics most effectively. Thermodynamic parameters revealed the feasibility, nonspontaneity and exothermic nature of adsorption. In addition, the isosteric heat of adsorption was independent of surface loading indicating the Sylopute used as an energetically homogeneous surface.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.1
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• pp.8-15
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• 2013

Little research has been conducted to explore the heavy metal removal potential of biochar. The adsorption characteristics of heavy metals by sesame waste biochar (pyrolysis at $600^{\circ}C$ for 1 hour) as heavy metal absorbent were investigated. The sesame waste biochar was characterized by SEM-EDS and FT-IR, and heavy metal removal was studied using Freundlich and Langmuir equations. The removal rates of heavy metals were higher in the order of Pb>Cu>Cd>Zn, showing that the adsorption efficiency of Pb was higher than those of any other heavy metals. Freundlich and Langmuir adsorption isotherms were used to model the equilibrium adsorption data obtained for adsorption of heavy metals on biochar produced from sesame waste. Pb, Cu, Cd and Zn equilibrium adsorption data were fitted well to the two models, but Pb gave a better fit to Langmuir model. Heavy metals were observed on the biochar surface after adsorption by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Main functional groups were aromatic C=O ring (at $1160cm^{-1}$, $1384cm^{-1}$ and $1621cm^{-1}$) by FT-IR analysis. Thus, biochar produced from sesame waste could be useful adsorbent for treating heavy metal wastewaters.

• Clean Technology
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• v.26 no.2
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• pp.122-130
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• 2020

The isotherm, kinetic, and thermodynamic parameters of reactive blue 4 adsorbed by activated carbon were investigated for activated carbon dose, pH, initial concentration, contact time, and temperature data. The adsorption of the RB 4 dye by activated carbon showed a concave shape in which the percentage of adsorption increased in both directions starting from pH 7. The isothermal adsorption data were applied to Langmuir, Freundlich, and Temkin isotherms. Both Freundlich and Langmuir isothermal adsorption models fit well. From determined Freundlich separation factor (1/n = 0.125 ~ 0.232) and Langmuir separation factor (R_L = 1.53 ~ 1.59), adsorption of RB 4 by activated carbon could be employed as an effective treatment method. The constant related to the adsorption heat (B_T = 2.147 ~ 2.562 J mol^-1) of Temkin showed that this process was physical adsorption. From kinetic experiments, the adsorption process followed the pseudo second order model with good agreement. The results of the intraparticle diffusion model showed that the inclination of the first straight line representing the surface diffusion was smaller than that of the second straight line representing the intraparticle pore diffusion. Therefore, it was confirmed that intraparticle pore diffusion is the rate-controlling step. The negative Gibbs free energy change (ΔG = -3.262 ~ -7.581 kJ mol^-1) and the positive enthalpy change (ΔH = 61.08 kJ mol^-1) indicated the spontaneous and endothermic nature of the adsorption process, proving this process to be spontaneous and endothermic.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.247-252
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• 2005

The typical treatment method for fluoride polluted water is the flocculation and precipitation method which usually is capable of reducing the fluoride concentration down to the level of about 10 ppm. However, this method is no longer effective for the treatment of contaminated water having less than 10 ppm of fluorides. To remove fluorides in polluted water from the fluoride concentration between 1 to 10 ppm, several adsorbents were prepared mainly based on an activated alumina and the fluoride removal efficiencies of the adsorbents were analyzed. The best fluoride removal efficiency was obtained when the activated alumina treated by sulfuric acid was used as the adsorbent. A proper calcination temperature for the sulfuric acid contained activated alumina was found to be about $500^{\circ}C$. An adsorption isotherm for the adsorbent was also obtained by using Freundlich model. The values of the constants in Freundlich isotherm model were calculated to be K=6.63 and 1/n=0.29 based on the results obtained from the series of batch type adsorption experiments.