• Membrane and Water Treatment
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• 제1권2호
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• pp.93-101
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• 2010

This study examined the effects of feed water chemistry and membrane fouling on the rejection of trace organics by a loose nanofiltration membrane. One ionisable and one non-ionisable trace organics were selected for investigation. Results reported here indicate that the solution pH and ionic strength can markedly influence the removal of the ionisable trace organic compound sulfamethoxazole. These observations were explained by electrostatic interactions between the solutes and the membrane surface and by the speciation of the ionisable compound. On the other hand, no appreciable effects of solution pH and ionic strength on the rejection of the neutral compound carbamazepine were observed in this study. In addition, membrane fouling has also been shown to exert some considerable impact on the rejection of trace organics. However, the underlying mechanisms remain somewhat unclear and are subject to on-going investigation.

• Membrane and Water Treatment
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• 제1권3호
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• pp.181-192
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• 2010

A linear quantitative structure-property relationship (QSPR) model is presented for the prediction of rejection in permeation through membrane. The model was produced by using the multiple linear regression (MLR) technique on the database consisting of retention data of 25 pesticides in 4 different membrane separation experiments. Among the 3224 different physicochemical, topological and structural descriptors that were considered as inputs to the model only 50 were selected using several criteria of elimination. The physical meaning of chosen descriptor is discussed in detail. The accuracy of the proposed MLR models is illustrated using the following evaluation techniques: leave-one-out cross validation procedure, leave-many-out cross validation procedure and Y-randomization.

• Nuclear Engineering and Technology
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• 제44권1호
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• pp.79-88
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• 2012

Migration tests were performed with conservative tracers in a fractured zone that had a single fracture of about 2.5 m distance at the KURT. To interpret the migration of the tracers in the fractured rock, a solute transport model was developed. A two dimensional variable aperture channel model was adopted to describe the fractured path and hydrology, and a particle tracking method was used for solute transport. The simulation tried not only to develop a migration model of solutes for open flow environments but also to produce ideas for a better understanding of solute behaviours in indefinable fracture zones by comparing them to experimental results. The results of our simulations and experiments are described as elution and breakthrough curves, and are quantified by momentum analysis. The main retardation mechanism of nonsorbing tracers, including matrixdiffusion, was investigated.

• Korean Membrane Journal
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• 제2권1호
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• pp.56-59
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• 2000

The surface charge properties of a polymeric NF and a ceramic UF membranes were characterized in terms of zeta potential and acidity. Both the negative zeta potential and acidity values increased as pH increases due to ionizable acidic functional groups. Increased ionic strength reduced the acidity of the negatively-charged membrane surface as anticipated. Through these results, it can be envisioned are used to reject solutes with ionizable functional groups. Fouling of the negatively-charged membrane with natural organic matter (NOM) having a negative charge density was also investigated with respect to the surface charge. The surface charge of the NF membrane increased negatively when greater NOM adsorption onto the membrane surface occured.

• Bulletin of the Korean Chemical Society
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• 제23권3호
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• pp.459-468
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• 2002

Literature data measured by the author have been processed to report on the effect of solute structure on gas liquid partition coefficients of eleven normal, branched and cyclic alkanes ranging in carbon number from five to nine in sixty nine low molecular weight liquids. The alkane solutes are n-pentane(p), n-hexane(hx), n-heptane(hp), n-octane(o), n-nonane(n), 2-methylpentane(mp), 2,5-dimethylpentane(dp), 2,5-dimethylhexane(dh), 2,3,4-trimethylpentane(tp), cyclohexane(ch), and ethylcyclohexane(ec). The solvent set encompasses most of those studied by Rohrschneider as well as three homologous series of solvents (n-alkanes, 1-alcohols and 1-nitriles) and several perfluorinated alkanes and highly fluorinated alcohols. An excellent linear relationship was observed between lnK and the carbon number of n-alkanes. The effective carbon numbers of branched and cyclic alkanes were determined in a similar fashion to the method of Kovats index. We found that the logarithm of solute vapor pressure multiplied by solute molar volume was a perfect descriptor for the linear relationship with the median effective carbon number.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.393-396
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• 2005

The reactive transport model on the biologically mediated sequential nitrate transformation and its subsequent transport was developed and tested. This model was coded as a reaction module within the RT3D framework (Clement, 1997). Transports of the reasonable six mobile solutes (dissolved organic carbon, $O_2,\;{NO_3}^-,\;{NO_2}^-,\;N_2O,\;N_2$) and two immobile microbes were simulated. The simulation results gave a reasonable match with supposed transport pattern. For the next step, the developed model will be validated against experimental data.

• Bulletin of the Korean Chemical Society
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• 제14권2호
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• pp.250-255
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• 1993

A dual capillary column system is described for the simultaneous analysis of a given sample and measurement of retention index (RI) and area ratio (AR) values of each peak on two capillary columns of different polarity, DB-5 & DB-1701 from a single injection. Both capillary columns were connected to either a splitless injector or an on-column injector via a deactivated fused-silica capillary tubing of 1 m length and a 'Y' splitter. Both injection modes allowed to measure RI and AR values with high reproducibility (<0.01% RSD) and high accuracy (<10% RE), respectively with the exception that the trace and high boiling solutes required the on-column mode for the accurate quantification and AR comparison. When the dual capillary column system in on-column injection mode was applied to the blind samples containing organic acids, each acid was positively indentified by the combined computer RI library search-AR comparison.

• 대한화학회지
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• 제31권1호
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• pp.55-63
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• 1987

본 연구는 결합 정지상 컬럼을 이용한 역상 액체 크로마토그래피에서 치환기에 따른 시료의 용리거동을 알아 보기 위한 일련의 연구로서 비교적 극성인 치환체에서 비극성인 치환체까지 18종의 벤젠 일치환체를 대상으로 $\mu$-Bondapak $C_{18} 컬럼 및 $\mu$-Bondapak phenyl컬럼상에서 메탄올-물, 아세토니트릴-물, 및 THF-물의 혼합용액을 이동상으로 하여 시료의 용리거동을 알아 보았다. 극성인 치환기를 갖는 치환체들의 용량인자(k')는 벤젠에 k'값보다 적었으며, 반대로 비극성인 치환체들의 k'값은 벤젠보다 컸다. 이동상중의 유기용매의 농도가 감소함에 따라 모든 벤젠 일치환체들의 용량 인자값은 증가하였다. 혼합물의 분리의 가능성을 예측하고 치환체들의 용리거동을 설명하기 위하여 컬럼의 종류 및 이동상의 종류에 따라 달라지는 각 치환체들의 머무름의 변화를 벤젠을 기준으로 하여 용량인자의 절대치의 차(${\Delta}k$')로 도식화하였다. 두 컬럼과 세가지 용매시스템에서 치환체들의 용량인자를 상호 비교하므로써 선택성이 큰 용매시스템을 조사하였다.

• 멤브레인
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• 제29권2호
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• pp.111-121
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• 2019

정삼투 공정에 유용한 유도용질로서 diethyl malonate를 사용한 citrate 계열의 유기 화합물을 합성하였다. 최종적으로 얻은 potassium pentane-1,3,3,5-tetracarboxylate는 $^1H-NMR$과 $^{13}C-NMR$을 통하여 확인하였다. 유도용질의 물성을 확인하기 위해 삼투압, 용해도, 수투과도, 역염 투과도를 측정하였다. 합성한 유도용액을 사용하여 정삼투 공정을 진행한 결과, 동일한 citrate 계열인 trisodium citrate 및 tripotassium citrate보다 높은 수투과량을 나타내었으며 염의 역확산 정도는 NaCl에 비하여 매우 낮은 값을 나타내었다. 합성된 유도용질의 삼투압은 NaCl보다 약 25% 낮았으나 물에 대한 용해도는 NaCl의 8.8배인 317 g/100 g water의 값을 나타내었다. 정삼투 종료 후 유도용질의 회수를 위해 상용화된 나노여과막을 사용하였고, 낮은 압력에서 효율적으로 회수가 가능하였다.

• Membrane and Water Treatment
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• 제5권2호
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• pp.123-146
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• 2014

Safe water has becoming a competitive resource in many parts of the world due to increasing population, prolonged droughts, climate change etc. The development of economical and stable materials and methods for providing the fresh water in adequate amounts is the need of the water industry. Nanomaterials have unique characteristics e.g., large surface areas, size, shape, and dimensions etc. that make them particularly attractive for removing various contaminants from polluted waters. Nanotechnology based multifunctional and highly efficient membrane processes are providing affordable solutions in the new era that do not rely on large infrastructures or centralizes systems. The objective of the current study is to review the possible applications of the membrane based nanomaterials/composites for the removal of various contaminations from polluted waters. The article will briefly overview the availability and practice of different nanomaterials based membranes for removal of bacteria and viruses, organic compounds and inorganic solutes etc. present in surface water, ground water, seawater and/or industrial water. Finally, recommendations are made based on the current practices of nanofiltration membranes in water industry for a stand-alone membrane filtration system in removing various types of contaminants from polluted waters.