• Membrane and Water Treatment
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• 제12권2호
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• pp.59-64
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• 2021

The rejection of sodium chloride (NaCl) and calcium chloride (CaCl2) single salt solutions were carried out for commercial nanofiltration NFDK membrane. Results showed that the NFDK membrane had a negative surface charge and had a higher observed rejection of 93.65% for calcium (Ca2+) ion and 78.27% for sodium (Na+) ions. Prediction of rejection for aqueous solutions of both salts was made using Donnan Steric Pore Model based on Extended Nernst-Planck Equation in addition to concentration polarization film theory. A MATLAB program was developed to execute the model calculations. Absolute Average Relative Error (% AARE) was found below 5% for real rejection of the NFDK membrane. This research could be used successfully to assess the membrane characterization parameter using a proposed procedure which can reduce the number of experiments.

• 한국막학회:학술대회논문집
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• 한국막학회 2003년도 추계 총회 및 학술발표회
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• pp.128-131
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• 2003

• 한국산학기술학회논문지
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• 제3권2호
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• pp.146-155
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• 2002

Surface complexation models employ mass law equations to describe the reaction of surface functional groups with ions in the solution and also Gouy-Chapman theory to consider the electrostatic effects in the surface reactions. In current surface complexation models, however, the coulombic factors used are not wholly consistent with the Gouy-Chapman model of the surface. This study was to provide the derivation of the coulombic term usually employed and then a revised coulombic term completely consistent with Gouy-Chapman Theory. The electrical potential energy. zF${\psi}$, in current surface complexation models is not consistent with the Gouy-Chapman theory with the potential gradient close to the charged surface but with the Donnan model with the uniform potential. Even though the new coulombic factor yielded lower surface potential, it provided worse fits for acid-base titration data of the goethite suspensions.

• 한국미생물·생명공학회지
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• 제27권4호
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• pp.320-326
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• 1999

The effects of operating pressure, lactate concentration, impurities, and pH on solution flux and lactate rejection in nanofiltration were investigated with model sodium lactate solutions (lactate 10~200g/L) as a model system. In the tested range of pressure(80~140 psig), the solution flux was observed to be proportional to the operating pressure and the rejection of lactate increased only slightly with the pressure. Both of the flux and the rejection decreased with lactate concentration, while the recovery rate of lactate increased. The effects of glucose and yeast extract as impurities on lactate rejection were negligible, but the flux decreased significantly with the addition of yeast extract. At low lactate concentrations, the rejection of lactate increased with pH due to the increased repulsion (Donnan exclusion effect) between lactate ions and membrane surface. But, at high lactate concentrations, the donnan effect was observed to be overwhelmed by the effect of sodium ions added to adjust the pH, and the rejection of lactate decreased with pH. When fermentation broth containing about 89g/L of lactate was nanofiltered, the flux and the rejection of lactate were 2.8L/$m^2$h and 5%, respectively at 120psig. Both of them were slightly lower than those with model solutions. The recovery rate was 2.6mol/$m^2$h.

• 공업화학
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• 제3권2호
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• pp.349-359
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• 1992

염료속에 함유된 무기염(NaCl, $Na_2SO_4$)의 선택적 제거를 위해 역확산과 역삼투를 결합한 방법과 nanofiltration(NF)을 각각 이용하였다. 역확산에 의한 염의 제거율은 염의 종류에 따라 1회(one pass)에 1~30%를 나타냈으며 염과 염료의 분리비는 10~500의 매우 큰 값을 갖는 반면 염료의 손실율은 0.3% 이하였다. 염료용액을 순환시킬수록 음이온인 $Cl^-$ 이온의 제거율이 증가하고 양이온인 $Na^+$ 이온의 제거율이 감소하는 도난투석현상이 관찰되었다. 또한 공급용액의 유속이 염의 제거에 미치는 영향을 살펴보았다. 역확산에 의해 염이 제거된 염료를 평판형 역삼투막을 사용하여 농축하였으며 $Cl^-$ 이온의 배제율을 solution-diffusion 모델식에 적용하였다 2회의 Diafiltration(DF)을 수행한 NF에서도 역확산에서와 마찬가지로 도난투석에 의해 $Cl^-$ 이온의 배제율 감소와 음배제율을 관찰하였다. 특히 두번째 DF에서 도난투석의 효과는 더욱 크게 나타났다.

• Membrane and Water Treatment
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• 제1권2호
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• pp.139-158
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• 2010

This work focuses on the application of nanofiltration (NF) to the concentration of a pharmaceutical product, Clavulanate ($CA^-$), from clarified fermentation broths, which show a complex composition with six main identified ions ($K^+$, $Cl^-$, ${NH_4}^+$, $H_2{PO_4}^-$, ${SO_4}^{2-}$ and $CA^-$), glucose and glycerol. The solutes transport through the NF membrane pores was investigated using the SEDE (Steric, Electric and Dielectric Exclusion) model. This model was applied to predict the rejection rates of the initial feed solution and the final concentrated solution (10-fold concentrated solution). The best results were achieved with a single fitted parameter, ${\varepsilon}_p$ (the dielectric constant of the solution inside pores) and considering that the membrane selectivity is governed by steric, electric (Donnan) and Born dielectric exclusion mechanisms. While the predicted intrinsic rejections of solutions comprising up to six ions and uncharged solutes were in good agreement with the experimental values, the deviations were much larger for the 10-fold concentrated solution.

• Membrane and Water Treatment
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• 제2권3호
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• pp.187-205
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• 2011

The electric transport of the mixture of hydrochloric and phosphoric acids through strong base (Neosepta ACM) and weak base (Selemion AAV) anion-exchange membranes was investigated. The instantaneous efficiency of HCl removal from the cathode solution, $CE_{Cl}$, with and without $H_3PO_4$ was determined. It was found that $CE_{Cl}$ was 0.8-0.9 if the number of moles of elementary charge passed through the system, $n_F$, did not exceed ca. 80% of the initial number of HCl moles in the cathode solution, $n_{Cl,ca,0}$. The retention efficiency of $H_3PO_4$ in that range was close to one. The transport of acid mixtures was satisfactorily described by a model based on the extended Nernst-Planck and Donnan equations for $n_F$ not exceeding $n_{Cl,ca,0}$. Among the tested model parameters, most important were: concentration of fixed charges, the porosity-tortuosity coefficient, and the partition coefficient of an undissociated form of $H_3PO_4$. For the both membranes, the obtained optimal values of fixed charge concentration, $\bar{c}_m$, were up to 40% lower than the literature values of $\bar{c}_m$ obtained from the equilibrium measurements. Regarding the $H_3PO_4$ equilibria, it was sufficient to consider $H_3PO_4$ as a monoprotic acid.