• 상하수도학회지
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• 제25권3호
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• pp.359-366
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• 2011

The feasibility of using volcanic ash for lead ion removal from wastewater was evaluated. The adsorption experiments were carried out in batch tests using volcanic ash that was treated with either NaOH or HCl prior to the use. Volcanic ash dose, temperature and initial Pb(II) concentration were chosen as 3 operational variables for a $2^3$ factorial design. Ash dose and concentration were found to be significant factors affecting Pb(II) adsorption. The removal of Pb(II) was enhanced with increasing volcanic ash dose and with decreasing the initial Pb(II) concentration. Pb(II) adsorption on the volcanic ash surface was spontaneous reaction and favored at high temperatures. Calculation of Gibb's free energy indicated that the adsorption was endothermic reaction. The equilibrium parameters were determined by fitting the Langmuir and Freundlich isotherms, and Langmuir model better fitted to the data than Freundlich model. BTV(base-treated volcanic ash) showed the maximum adsorption capacity($Q_{max}$) of 47.39mg/g. A pseudo second-order kinetic model was fitted to the data and the calculated $q_e$ values from the kinetic model were found close to the values obtained from the equilibrium experiments. The results of this study provided useful information about the adsorption characteristics of volcanic ash for Pb(II) removal from aqueous solution.

• 대한환경공학회지
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• 제30권9호
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• pp.907-912
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• 2008

본 연구는 지표수나 호소수 등에서 유기 및 무기오염물질의 저감을 위해 반응매질로서 사용되는 black shale 및 영가철의 수중의 무기인산염을 흡착제거하는 데 있어서의 정량적 특성을 알아보았다. 무기인산염의 회분식 흡착실험에는 갯벌에서 마련한 퇴적토, black shale, 영가철이 흡착제로 사용되었으며 인산염의 흡착에 미치는 영향을 공존 칼슘이온의 농도를 0, 1, 5 mM로 변화시켜 실험하였다. 칼슘이온의 공존과 함께 세 흡착제에 대한 인산염 농도감소를 빠른 흡착계수(k$_f$), 느린 흡착계수(k$_s$)과 침전계수(k$_p$)로 구성된 kinetic model을 이용하여 해석하였다. 등온흡착의 결과는 Langmuir와 Freundlich 모델을 적용하였으며 퇴적토, black shale, 영가철에 대한 Freundlich 모델의 K$_f$값은 각각 1.141, 7.721, 그리고 4.873였다. 공존하는 칼슘이온과의 침전가능성으로 인하여 kinetic model에서는 칼슘농도와 침전제거간의 상관관계가 있었으나 등온흡착식에서 인산염의 최대흡착량에는 칼슘농도가 영향을 미치지 않았다.

• Environmental Engineering Research
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• 제14권3호
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• pp.164-169
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• 2009

A powder form of aluminum (hydr)oxides is not suitable in wastewater treatment/filtration systems because of low hydraulic conductivity and large sludge production. In this study, aluminum (hydr)oxide-coated sand (AOCS) was used to remove phosphate from aqueous solution. The properties of AOCS were analyzed using a scanning electron microscopy (SEM) combined with an energy dispersive X-ray spectrometer (EDS) and an X-ray diffractometer (XRD). Kinetic batch, equilibrium batch, and closed-loop column experiments were performed to examine the adsorption of phosphate to AOCS. The XRD pattern indicated that the powder form of aluminum (hydr)oxides coated on AOCS was similar to a low crystalline boehmite. Kinetic batch experiments demonstrated that P adsorption to AOCS reached equilibrium after 24 h of reaction time. The kinetic sorption data were described well by the pseudo second-order kinetic sorption model, which determined the amount of P adsorbed at equilibrium ($q_e$ = 0.118 mg/g) and the pseudo second-order velocity constant (k = 0.0036 g/mg/h) at initial P concentration of 25 mg/L. The equilibrium batch data were fitted well to the Freundlich isotherm model, which quantified the distribution coefficient ($K_F$ = 0.083 L/g), and the Freundlich constant (1/n = 0.339). The closed-loop column experiments showed that the phosphate removal percent decreased from 89.1 to 41.9% with increasing initial pH from 4.82 to 9.53. The adsorption capacity determined from the closed-loop experiment was 0.239 mg/g at initial pH 7.0, which is about two times greater than that ($q_e$ = 0.118 mg/g) from the kinetic batch experiment at the same condition.

• Carbon letters
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• 제8권3호
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• pp.199-206
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• 2007

The activated carbon produced from rubber wood sawdust by chemical activation using phosphoric acid have been utilized as an adsorbent for the removal of Cu(II) from aqueous solution in the concentration range 5-40 mg/l. Adsorption experiments were carried out in a batch process and various experimental parameters such as effect of contact time, initial copper ion concentration, carbon dosage, and pH on percentage removal have been studied. Adsorption results obtained for activated carbon from rubber wood sawdust were compared with the results of commercial activated carbon (CAC). The adsorption on activated carbon samples increased with contact time and attained maximum value at 3 h for CAC and 4 h for PAC. The adsorption results show that the copper uptake increased with increasing pH, the optimum efficiency being attained at pH 6. The precipitation of copper hydroxide occurred when pH of the adsorbate solution was greater than 6. The equilibrium data were fitted using Langmuir and Freundlich adsorption isotherm equation. The kinetics of sorption of the copper ion has been analyzed by two kinetic models, namely, the pseudo first order and pseudo second order kinetic model. The adsorption constants and rate constants for the models have been determined. The process follows pseudo second order kinetics and the results indicated that the Langmuir model gave a better fit to the experimental data than the Freundlich model. It was concluded that activated carbon produced using phosphoric acid has higher adsorption capacity when compared to CAC.

• Advances in nano research
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• 제9권3호
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• pp.173-181
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• 2020

Adsorption and heterogeneous electro-Fenton process using iron-loaded ZSM-5 nano-zeolite were investigated for the removal of Tetracycline (TC) from wastewater. The nano-zeolite was synthesized hydrothermally and modified through impregnation. The zeolite was characterized by XRD, FT-IR, FE-SEM, N₂ adsorption-desorption, and NH₃-TPD techniques. The equilibrium data were best represented by the Freundlich isotherm. The pseudo-second-order kinetic model was the most accurate model for the adsorption of TC on the modified nano-zeolite. The effect of parameters such as pH of solution and current density were investigated for the heterogeneous electro-Fenton process. The results showed that the current density of 150 mA and pH of 3 led to the highest TC removal (90.35%) at 50 min. The nano-zeolite showed the appropriate reusability. Furthermore, the developed kinetic model was in good agreement with the removal data of TC through the electro-Fenton process.

• 청정기술
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• 제25권1호
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• pp.56-62
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• 2019

입상 활성탄에 의한 murexide 흡착의 평형, 동역학 및 열역학 파라미터들에 대해 조사하였다. 실험은 흡착제의 양, 염료의 초기농도, 접촉시간과 온도를 변수로 하여 회분식 실험으로 진행하였다. 등온흡착평형관계는 293 ~ 313 K의 범위에서 Freundlich 식에 가장 잘 적용되었으며, Langmuir 식의 분리계수 $R_L$과 Freundlich 식의 분리계수 ${\beta}$로부터 입상 활성탄에 의한 murexide의 흡착조작이 적절한 처리방법이 될 수 있다는 것을 알았다. 또한 Dubinin- Radushkevich 식에서 얻은 흡착에너지(E)로부터 물리흡착공정임을 알 수 있었다. 흡착공정에 대한 동역학적 해석을 통해 반응속도식의 적용 결과는 유사이차반응식이 유사일차반응식보다 일치도가 높은 것으로 나타났다. Gibbs 자유에너지 변화($-0.1096{\sim}-10.5348kJ\;mol^{-1}$), 엔탈피변화($+151.29kJ\;mol^{-1}$)을 통해 흡착공정이 자발적 공정 및 흡열과정으로 진행되었음을 알 수 있었다. 또한 Gibbs 자유에너지 변화는 온도가 올라갈수록 감소하였기 때문에 입상 활성탄에 의한 murexide의 흡착반응은 온도가 올라갈수록 자발성이 높아졌다. 엔트로피 변화 ($512.4J\;mol^{-1}\;K^{-1}$)는 활성탄에 의한 murexide의 흡착반응이 일어나는 동안 고-액 계면에서 무질서도가 증가함을 나타냈다.

• 한국환경과학회지
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• 제14권9호
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• pp.881-888
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• 2005

The biosorption of dye, Rhodamine B(Rh-B), onto waste activated sludge was investigated. The biosorption capacity and contact time were shown as a simulation of dye adsorption equilibrium and kinetics models. We observed that biosorption of Rh-B occurred rapidly less than 4 hr. These experimental data could be better fitted by a pseudo-second-order rate equation than a pseudo-first-order rate equation. The equilibrium dependence between biosorption capacity and initial concentration of Rh-B was estimated and it was found that the equilibrium data of biosorption were fitted by four kinds of model such as Langmuir, Freundlich, Redlich-Peterson, and Koble-Corrigan model. The average percentage errors, $\varepsilon(\%)$, observed between experimental and predicted values by above each model were $21.19\%,\;9.97\%,\;10.10\%\;and\;11.76\%$, respectively, indicating that Freundlich and Redlich-Peterson model could be fitted more accrately than other models.

• 한국지반환경공학회 논문집
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• 제13권4호
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• pp.37-44
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• 2012

본 연구는 모래, HAP, Zeolite, 혼합여재에 의한 비점오염원 흡착 반응을 조사하였다. 오수에 대한 모래, HAP, Zeolite와 혼합여재의 흡착은 연속적인 회분식 실험을 통해 조사하였다. 회분식 실험 후 COD, T-N, T-P를 통하여 분석하였다. kinetic model은 유사 1차반응을 통해 분석하였다. Langmuir와 Freundlich isotherm model을 사용하여 적용성을 조사하였다. COD 최대흡착량$(Q_{max})$의 값은 각각 모래 0.0511mg/g, HAP 0.1905mg/g, Zeolite 1.0366mg/g, Mixed media 0.7444mg/g T-N 최대흡착량$(Q_{max})$의 값은 각각 모래 0.0159mg/g, HAP 0.0537mg/g, Zeolite 0.5496mg/g, Mixed media 0.1374mg/g T-P 최대흡착량$(Q_{max})$의 값은 각각 모래 0.0202mg/g, HAP 0.1342mg/g, Zeolite 0.0462mg/g, Mixed media 0.1180mg/g 나타났다. 결과적으로 혼합여재는 비점오염원을 효과적으로 제거하였다.

• Korean Chemical Engineering Research
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• 제59권4호
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• pp.565-573
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• 2021

활성탄에 의한 Brilliant Green(BG), Quinoline Yellow(QY) 염료의 흡착에 대한 등온선, 동력학, 열역학적 특성치와 경쟁흡착을 흡착제의 양, pH, 초기농도, 접촉시간 및 온도를 변수로 하여 수행하였다. BG와 QY는 가지고 있는 atomic nitrogen 이온(N⁺)의 영향으로 pH 11에서 92.4%의 최고 흡착율을 나타내었고, QY는 sulfite 이온(SO₃^-)의 영향으로 pH3에서 90.9%의 최고 흡착률을 나타냈다. 등온흡착 데이터로부터, BG의 경우는 Freundlich 등온식에 잘 맞아서 다분자층 흡착이었고, QY는 Langmuir 등온식이 가장 높은 일치도를 나타내어 주로 단분자층흡착이었다. Freundlich 식과 Langmuir 식의 분리계수는 활성탄에 의해 이들 염료를 효과적으로 처리할 수 있는 공정임을 나타냈다. Temkin 등온식에 의해 평가된 흡착 에너지는 활성탄에 의한 BG와 QY의 흡착이 물리 흡착임을 확인시켰다. 동력학적 실험결과는 유사 이차 반응속도식이 유사일차 반응속도식보다 일치도가 높았고 평형흡착량에 대한 오차도 더 작았다. 입자내 확산식을 이용하여 도시한 그래프는 2단계의 직선으로 나타났는데 기울기가 낮은 입자내 확산이 율속단계임을 확인하였다. 흡착공정의 활성화 에너지와 엔탈피 변화는 흡착과정이 비교적 수월하게 일어나며 흡열반응임을 나타냈다. 엔트로피 변화는 활성탄에 대한 BG와 QY 염료의 흡착이 진행됨에 따라 흡착시스템의 무질서도가 증가함을 나타냈고, Gibbs 자유 에너지 변화로 부터 흡착반응이 온도가 높아질수록 자발성이 더 커진다는 것을 알았다. 혼합용액의 경쟁흡착 결과는 상대적으로 흡착률이 높은 QY가 BG에 의해 큰 방해를 받아 흡착률이 크게 감소하는 것으로 나타났다.

• Carbon letters
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• 제10권1호
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• pp.23-32
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• 2009

The adsorption of phenolic compound resorcinol on activated carbons prepared from Moringa oleifera (Drumstick bark) has been investigated. Activated carbon was prepared by impregnating Moringa oleifera with 50% phosphoric acid in the ratio of 1:1 and 1:2(w/w), designated as MOAC1 and MOAC2. Equilibrium and isotherm studies were carried out. The influences of variables such as contact time, initial concentration of resorcinol, carbon dosage in the solution on percentage adsorption and adsorption capacity of the bark have been analysed. The equilibration time was found to be 4 h. Kinetics of resorcinol onto activated carbons was checked for pseudo first order and pseudo second order model. It was found that the adsorption of resorcinol follows pseudo second order kinetics for both MOAC1 and MOAC2. The isotherm data were correlated with isotherm models, namely Langmuir and Freundlich. Adsorption isotherms were satisfactorily fitted by both the Langmuir and Freundlich model for MOAC1 and MOAC2.