• Bulletin of the Korean Chemical Society
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• 제19권2호
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• pp.218-222
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• 1998

Removal of Cd(Ⅱ), Zn(Ⅱ) and Cu(Ⅱ) from aqueous solutions using the adsorption process on magadiite has been investigated. It was found that the removal percentage of metal cations at equilibrium increases with increasing temperature, and follows the order of Cd(Ⅱ) > Cu(Ⅱ) > Zn(Ⅱ). Equilibrium modeling of adsorption showed that the adsorptions of Cd(Ⅱ), Cu(Ⅱ), and Zn(Ⅱ) were fitted to Langmuir isotherm. Kinetic modeling of the adsorption showed that first order reversible kinetic model fitted to experimental data. From kinetic model and equilibrium data, the overall rate constant (k) and the equilibrium constant (K) for the adsorption process were calculated. The overall rates of adsorption of metal ions follow the order of Cd(Ⅱ) > Cu(Ⅱ) > Zn(Ⅱ). From the results of thermodynamic analysis, standard Gibbs free energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°) of adsorption process were calculated.

• 한국환경과학회지
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• 제27권3호
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• pp.167-177
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• 2018

The removal characteristics of As and Se ions from aqueous solution by hexadecyl trimethyl ammonium bromide (HTMAB) modified anthracite (HTMAB-AT) were investigated under various conditions of contact time, pH and temperature. When the pH is 6, the zeta potential value of anthracite (AT) is -24 mV and on the other hand, the zeta potential value of the HTMAB-AT is +44 mV. It can be seen that the overall increase of about 60 mV. Increasing the (+) potential value indicates that the surface of the adsorbent had a stronger positive charge, so adsorption for the anion metal was increased. The isotherm data was well described by Langmuir and Temkin isotherm model. The maximum adsorption capacity was found to be 7.81 and 6.89 mg/g for As and Se ions from the Langmuir isotherm model at 298 K, respectively. The kinetic data was tested using pseudo first and pseudo second order models. The results indicated that adsorption fitted well with the pseudo second order kinetic model. The mechanism of the adsorption process showed that adsorption was dependent on intra particle diffusion model according to two step diffusion. The thermodynamic parameters(${\Delta}G^{\circ}$, ${\Delta}H^{\circ}$, and ${\Delta}S^{\circ}$) were also determined using the equilibrium constant value obtained at different temperatures. The thermodynamic parameters indicated that the adsorption process was physisorption, and also an endothermic and spontaneous process.

• 공업화학
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• 제9권5호
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• pp.689-697
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• 1998

가교도와 희석제량을 변화시켜 제조한 인산기를 갖는 MR형 양이온 교환수지(RGP)에 대하여 우라늄의 흡착평형, 흡착속도 및 흡착 율속 단계를 고찰하였다. RGP 수지에 대한 우라늄의 흡착 평형은 가교도, 희석제량 및 흡착온도 변화 모두 Freundlich 등온식과 Langmuir 등온식으로 잘 나타났다. RGP수지에 대한 우라늄의 흡착량과 흡착속도는 흡착 온도가 증가함에 따라 증가하였으며 이때 흡착열은 ${\Delta}H=11kcal/mol$ 이었다. RGP 수지에 대한우라늄의 흡착속도는 가교도의 영향인 경우 RGP-10(50)>RGP-1(50)>RGP-2(50)>RGP-5(50)RGP-0(50)>이며, 희석제량의 영향인 경우 RGP-2(75)>RGP-2(100)>RGP-2(50)>RGP-2(30)>RGP-2(0) 순으로 증가하였다. RGP수지에 대한 우라늄의 확산저항은 분자확산<세공확산<표면확산 순이었으며, 수지내의 우라늄의 확산 율속은 세공 확산보다 표면 확산이 율속이었다.

• 한국지반환경공학회 논문집
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• 제12권11호
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• pp.31-37
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• 2011

본 연구는 Hydroxyapatite(HAP)/$TiO_{2}$ 여재에 의한 Reactive Black 5(RB5)의 흡착과 광촉매 반응을 조사하였다. RB5에 대한 $TiO_{2}$, HAP와 $TiO_{2}$/HAP의 흡착은 연속적인 회분식 실험을 통해 조사하였다. 흡착평형에 따른 결과를 나타내었으며 Langmuir와 Freundlich isotherm model을 사용하여 적용성을 조사하였다. $TiO_{2}$, HAP와 $TiO_{2}$/HAP 흡착제별 흡착평형 결과는 Langmuir isotherm model에 적합하였으며 최대흡착량(Qmax)의 값은 각각 단일 $TiO_{2}$는 5.28mg/g, 단일 HAP는 12.45mg/g, $TiO_{2}$/HAP는 9.03mg/g으로 나타났다. 흡착과 광촉매 반응에 대한 kinetic model들은 유사 1차 반응을 통해 분석하였으며, 이들 model에 따르면 $TiO_{2}$/HAP에 의한 RB5 제거는 광촉매 반응과 흡착반응의 상호작용의 영향을 받는 것으로 나타났다.

• 한국환경보건학회지
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• 제24권3호
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• pp.41-47
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• 1998

The purpose of this research is evaluation of adsorption capacity of the cast for TCE comparing with the yellow clay. Furthermore, the experimental data was fitted with the Langmuir and Freundlich isotherm and was found to be apllicable to the adsorption isotherm equation. The soil bed reactor used in this study was made of glass(10 cm in diameter, 100 cm in depth). The cast and yellow clay used as adsorbents were screened with 8-20 mesh mecanically. Results from Equilibrium test with adsorbents showed that the equibrium time of the cast and yellow clay was 9min independent of the amount of the adsorbents. The adsorption efficiencys of the cast and yellow clay for TCE was 66.3% and 56.2%, respectively. In the application of Freundlich isotherm, 1/n of the cast and yellow clay were 0.786 and 0.704, respectively. These results showed that the cast was more available than the yellow clay as TCE adsorbent. The best adsorption capacity was showed at 0% moisture content, 70 ppm inlet concentration and 25$^{\circ}$C temperature.

• Korean Chemical Engineering Research
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• 제54권2호
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• pp.255-261
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• 2016

활성탄을 사용한 Acid Yellow 14 염료의 흡착 실험은 흡착제의 양, pH, 초기농도, 접촉시간과 온도를 흡착변수로 사용하여 수행하였다. 흡착평형자료는 Langmuir, Freundlich 및 Temkin 등온식을 사용하여 해석하였는데, Freundlich 식이 가장 좋은 일치도를 나타냈다. 평가된 Freundlich 상수(1/n=0.129~0.212)와 Langmuir 분리계수($R_L=0.202{\sim}0.243$)로부터 활성탄에 의한 Acid Yellow 14의 흡착조작은 적절한 처리방법이 될 수 있음을 알았다. Temkin의 흡착열관련상수(B)는 5.101~9.164 J/mol로 평가되어, 흡착공정이 물리흡착임을 알았다. 흡착속도실험자료를 유사일차반응속도식과 유사이차반응속도식에 적용해 본 결과, 흡착동력학은 유사이차반응속도식에 잘 맞는 것으로 나타났다. Gibbs 자유에너지(-4.81~-10.33 kJ/mol)와 엔탈피(+78.59 kJ/mol)는 흡착이 자발적이고 흡열공정으로 진행된다는 것을 나타낸다.

• 공업화학
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• 제30권2호
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• pp.190-197
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• 2019

활성탄을 사용하여 수용액으로부터 메틸 그린 염료의 흡착에 대해 초기농도와 접촉시간 및 온도를 흡착변수로 사용하여 조사하였다. 흡착평형관계는 Freundlich 등온식에 잘 맞았다. 평가된 Freundlich 분리계수(1/n = 0.212~0.305)로부터 이 흡착공정이 효과적인 처리영역(0 < $R_L$ < 1)에 속하는 것을 알았다. BET식으로부터 얻은 등온포화용량은 온도가 증가할수록 커졌다. Dubinin-Radushkevich식으로 구한 흡착에너지값(E = 316.869~340.049 J/mol)으로부터 흡착공정이 물리흡착공정임을 알았다. 흡착속도실험결과는 유사 2차 반응속도식에 잘 맞는 것으로 나타났다. 자유에너지(-5.421~-7.889 kJ/mol)와 엔탈피(31.915 kJ/mol)는 흡착공정이 자발적이고 흡열반응으로 진행되었다고 알려주었다. 등량흡착열은 평형흡착량이 증가함에 따라 커졌으며, 표면 덮임이 증가됨에 따라 흡착제-흡착질의 총 상호작용도 증가하였다.

• Korean Chemical Engineering Research
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• 제44권5호
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• pp.460-467
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• 2006

Zeolite 5A 촉매에서 $H_2$, CO, $CO_2$에 대한 단성분 및 혼합성분의 흡착평형 실험을 정적부피법에 의해 수행하였다. 실험 데이타는 온도범위 293.15 K, 303.15 K, 313.15 K이고, 압력범위는 25 atm까지로 하여 얻었다. 각각의 파라미터들은 단성분 실험을 통해 얻었고, 이를 통해 혼합성분의 흡착 평형을 예측하였으며 실험값과 비교하였다. Zeolite 5A 에서의 $H_2/CO_2$, $CO/CO_2$ 혼합가스의 흡착평형 실험 결과는 Langmuir isotherm, Langmuir-Freundlich isotherm and Dual-Site Langmuir isotherm을 이용해 예측하였다. 그 결과 Dual-Site Langmuir isotherm모델이 가장 유사한 예측을 하는 것으로 나타났다.

• Environmental Engineering Research
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• 제13권2호
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• pp.79-84
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• 2008

Adsorption of heavy metals by sawdust was investigated to evaluate the effectiveness of using sawdust to remove heavy metals from aqueous solutions. Kinetic and isotherm studies were carried out by considering the effects of initial concentration and pH. The adsorption isotherms of heavy metals fitted the Langmuir or Freundlich model reasonably well. The adsorption capacity of metal was in the order $Pb^{2+}$ > $Cu^{2+}$ > $Zn^{2+}$. A high concentration of co-existing ions such as $Ca^{2+}$ and $Mg^{2+}$ depressed the adsorption of heavy metal. Adsorption data showed that metal adsorption on sawdust follows a pseudo-second-order reaction. Kinetic studies also indicated that both surface adsorption and intraparticle diffusion were involved in metal adsorption on sawdust. Column studies prove that sawdust could be effective biosorbent for the removal of heavy metals from aqueous phase.

• Advances in environmental research
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• 제4권2호
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• pp.119-133
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• 2015

Water pollution means that the physical, chemical and biological properties of water are changing. In this study, adsorption was chosen as the treatment method because it is an eco-friendly and low cost approach. Magnetite is a magnetic material that can synthesize chemical precipitation. Magnetite was used for the removal of copper in artificial water samples. For this purpose, metal removal from water dependent on the pH, initial concentration of metal, amount of adsorbent and effect of sorption time were investigated. Magnetite was characterized using XRD, SEM and particle size distribution. The copper ions were determined by atomic absorption spectrometry. The adsorption of copper on the magnetite was studied in a batch process, with different aqueous solutions of Cu (II) at concentrations ranging from 10 to $50mg\;l^{-1}$. Optimum conditions for using magnetite were found to be concentration of $10mg\;L^{-1}$, pH: 4.5, contact time: 40 min. Optimum adsorbent was found to be 0.3 gr. Furthermore, adsorption isotherm data were analyzed using the Langmuir and Freundlich equations. The adsorption data fitted well with the Freundlich ($r^2=0.9701$) and Langmuir isotherm ($r^2=0.9711$) equations. Kinetic and equilibrium aspects of the adsorption process were studied. The time-dependent Cu (II) adsorption data were described well by a pseudo-second-order kinetic model.