• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2001년도 총회 및 춘계학술발표회
• /
• pp.89-92
• /
• 2001

This study aims at investigating the relationship between dispersion coefficient ratio to molecular diffusion coefficient (D$_{l}$ /D$_{m}$) and Peclet number (Pe) for multi-solute system in non-Darcian flow regime. Existing understanding on solute dispersion is primarily derived from one-solute system in Darcian flow regime. We found that solute dispersion in rock fractures can be characterized by the mechanism of both macrodispersion and Taylor dispersion, even for non-Darcian f]ow domain. For the Darcian flow regime even different solutes lead to the same D$_{l}$ /D$_{m}$ at same Pe. However, as the flow becomes non-Darcian, solute with a higher molecular diffusion coefficient result in higher D$_{l}$ /D$_{m}$ at tile same Pe than that with a lower diffusion coefficient.cient.

• Membrane and Water Treatment
• /
• 제1권2호
• /
• pp.93-101
• /
• 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
• /
• 제1권3호
• /
• pp.181-192
• /
• 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
• /
• 제44권1호
• /
• pp.79-88
• /
• 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.

• Progress in Superconductivity
• /
• 제6권2호
• /
• pp.124-128
• /
• 2005

Homogeneous and fine powders for Bi-2223 tape were prepared by ultrasonic spray pyrolysis (SP) method from an aqueous solution of metal nitrates. Bi-2223 precursor powders were synthesized with various solutes concentration and pyrolysis temperature. The synthesized precursor powders had a narrow particle size distribution and an average particle size was $\~{\cal}um$. The reactivity of precursor powder by SP method is very high, attributed to the fine and narrow particle size distribution. Bi-2223/Ag tape was prepared using PIT method and followed by various sintering conditions. The precursor powder by SP method promoted a very quick formation of the Bi-2223 phase for short sintering time while the secondary phase such as large AEC phase and $Ca_2PbO_4$ were minimized for SP tapes.

• Korean Membrane Journal
• /
• 제2권1호
• /
• pp.56-59
• /
• 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
• /
• 제23권3호
• /
• pp.459-468
• /
• 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.

• Environmental Engineering Research
• /
• 제14권2호
• /
• pp.126-133
• /
• 2009

This study investigated the removal characteristics of various micro organic compounds by low-pressure nanofiltration membranes comprised of disinfection by products and pharmaceutically active compounds. The experimental removal of micro organic compounds by low-pressure nanofiltration membranes was compared with the transport model calculations, which consist of diffusion and convection terms including steric hindrance factor. The selected molecule from the disinfection byproducts and pharmaceutical active compounds showed a much lower removal than polysac-charides with a similar molecular size. However,the difference between model calculation and experimental removal of disinfection by-products and pharmaceutically active compounds could be corrected. The correlation of Ks with solute radius was further considered to clarity transport phenomena of micro organic solutes through nanofiltration membranes.

• 한국염색가공학회지
• /
• 제7권2호
• /
• pp.63-69
• /
• 1995

To improve the blood compatibility of chitosan membranes, 2-(methacryloyloxy)-ethyl-2-(trimethylammonium)ethyl phosphate(MTP), which is a methacrylate with phospholipid polar groups, was grafted on the surface of chitosan membranes and the biocompatibility of MTP-grafted chitosan membranes was investigated. The permeation coefficient gradually decreased with increasing in molecular weights of biocomponents below 10$^{4}$, and drastically decreased above 10$^{4}$. This result corresponds with the permeability of solutes in case of hemodialysis membranes. The MTP-grafted chitosan membranes displayed less blood cell adhesion than the chitosan membranes. This may due to the formation of biomembrane4ike surface by adsorption and arrangement of phospholipid molecules from serum onto the MTP copolymer surface.

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