• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.926-932
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• 2006

A series of bench-scale membrane filtration experiments were performed to systematically investigate the removal mechanisms of reverse osmosis (RO) and nanofiltration (NF) membranes for BTEX (benzene, toluene, ethylene, xylene), trichloroethylene (TCE) and tetrachloroethylene (PCE). The molecular weight of these organic compounds ranged from 78 to 166 dalton. The rejection of organic compounds by RO/NF membranes varied significantly from 59.6 to 99.2% depending on solute and membrane types. Specifically, experimental results demonstrated that the removal efficiency of RO/NF membranes increased as solute molecular characteristics such as W/L (molecular width/length) ${\times}$ $M_W$ (molecular weight) and octanol-water partition coefficient increased. This observation suggested that the rejection of small organic compounds by RO/NF membranes was determined by the combined effect of physical (molecular size and shape) and chemical (hydrophobicity) properties.

• Animal cells and systems
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• v.2 no.4
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• pp.455-462
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• 1998

A survey was conducted on the inorganic and organic solute patterns of plants in connection with nitrate metabolism according to different light regimes (1.9, 16.0, 91.5 $Wm^{-2}$). Besides measuring in vivo NRA, we also quantitatively analyzed ater-soluble inorganic ions, organic acids, low molecular weight carbohydrates, amino aciss and total N (% DW). Among 4 Carex species, C. pilosa is known as shade-adapted species and the others as half (C. gracilis) to full (C. rostrata & C. distans) light-adapted species. Compared to species adapted to high light intensity, shade-adapted C. pilosa showed reduced productivity under the highest light intensity. In general, nitrate and amino acid levels decreased at higher light intensity, while sugar and organic acid concentrations increased. In C. pilosa osmolality tended to rise with increasing light intensity, while in the other species it tended to fall. Under low light intensity, the drop in soluble carbohydrate contents is osmotically compensated for by an enhanced nitrate concentration. It is concluded that competition between nitrate and $CO_2$reduction for reductants and ATP from photosynthesis may have important ecological consequences for the adaptation of plants to low or high light conditions. Additionally, the patterns of ionic changes due to increased light intensities were essentially the same in all selected species, indicating similar characteristics of heir mineral ion and organic acid metabolism as well as in field-grown Carex species.

• Korean Journal of Agricultural Science
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• v.27 no.2
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• pp.125-134
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• 2000

This observation was to investigate the influence of raw organic matter incorporated into soil at various rates on hydraulic conductivity and elution of solute throughout soil column. Generally the organic matter content in a practical agricultural field was approximately 3%. However, the application rate of organic matter in the field tends to rapidly increase in these days. Therefore, we raised the application rate of organic matter up to 10% in this investigation. From the experiment, we found that the hydraulic conductivities rapidly decreased with increasing rate of organic matter as well as rapid decrease in total volume of eluent during the same period. And electrical conductivities in the effluent significantly decreased after 2 pore volume, resulting in approaching to the criteria of saline soli. From this we could assume that the organic matter may influence the crop growth in the beginning. However excessive irrigation in the field may cause saturation of soil leading to reduction of soil. Therefore, there must be a management methods in application of organic matter with respect to soil water control.

• Journal of Ecology and Environment
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• v.33 no.4
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• pp.289-298
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• 2010

A number of characteristics of the Lake H$\ddot{o}$vsg$\ddot{o}$l watershed, such as the lake's location at the edge of the Central Asian continuous permafrost zone, provide a unique opportunity to evaluate possible anthropogenic impacts in this remote area in northern Mongolia. In this study, we compared stream solute concentrations in six sub-watersheds in the Lake H$\ddot{o}$vsg$\ddot{o}$l watershed. Water samples were collected during the summer months between 2003 and 2005. Concentrations of $Cl^-$ ranged from 9.8 to $51.3\;{\mu}mol/L$; average nitrate concentrations were very low and ranged from undetectable to $1.1\;{\mu}mol/L$ and average ${SO_4}^{2-}$ concentration at sampling stations with minimal animal grazing ranged from 66 to $294\;{\mu}mol/L$. Average dissolved organic carbon (DOC) concentrations ranged from 642 to $1,180\;{\mu}mol$ C/L. We did not find statistically significant differences in DOC concentrations among the six streams, although DOC concentrations tended to be higher in the two northernmost streams, possibly related to differences in the active layer above the permafrost. Dissolved organic nitrogen (DON) concentrations were correlated with DOC concentration, and followed the same spatial pattern as those for DOC. In streams in this remote watershed, total dissolved nitrogen was made up of mostly organic N, as has been found for other regions distant from anthropogenic N sources. Overall, these results suggest that future research on the dynamics of DOC and DON in this watershed will be especially insightful in helping to understand how changes in climate and land use patterns will affect transformations, retention, and export of dissolved organic matter within these sub-watersheds in the Lake H$\ddot{o}$vsg$\ddot{o}$l region.

• Proceedings of the Zoological Society Korea Conference
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• 1997.10b
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• pp.126.1-126
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• 1997

No Abstract, See Full Text

• Journal of Soil and Groundwater Environment
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• v.27 no.6
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• pp.11-21
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• 2022

Sorption of phenanthrene (PHE) and pyrene (PYR) in several sorbents, i.e., natural soil, BionSoil^®, Pahokee peat, vermicompost and Devonian Ohio Shale and a surfactant (hexadecyltrimethyl ammonium chloride)-modified montmorillonite (HDTMA-M) were investigated. Pyrene exhibited higher sorption tendency than phenanthrene, as predicted by its higher octanol to water partition coefficient (K_ow). Several sorption models: linear, Freundlich, solubility-normalized Freundlich model, and Polanyi-Manes model (PMM) were used to analyze sorption isotherms. Linear isotherms were observed for natural soil, BionSoil^®, Pahokee peat, vermicompost, while nonlinear Freundlich isotherms fitted for Ohio shale and HDTMA-M. The relationship between sorption model parameters, organic carbon content (f_oc), and elemental C/N ratio was studied. In the binary competitive sorption of phenanthrene and pyrene in natural soil, competition between the solutes caused reduction in the sorption of each solute compared with that in the single-solute system. The ideal adsorbed solution theory (IAST) coupled with the single-solute Freundlich model was not successful in describing the binary competitive sorption equilibria. This was due to the inherent nature of linear sorption of phenanthrene and pyrene in natural soil. The result indicates that the applicability of IAST for the prediction of binary competitive sorption is limited when the sorption isotherms are inherently linear.

• Membrane Journal
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• v.33 no.6
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• pp.409-415
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• 2023

Apart from developing better membranes, a clever reconfiguration of membrane cascade process can improve the solute selectivity and minimize solvent consumption. In this work, solvent resistant cellulose nanofiltration membranes were fabricated and the solute rejection performance in various organic solvents were tested. Interestingly, cellulose membranes exhibited unique negative rejection profile in non-polar solvents. Such trend could be exploited to yield reverse selectivity, which showed that low molecular weight solute could be concentrated in the retentate. It was found that more than 3-fold solvent saving could be achieved at the same final purity.

• The Journal of Korean Academy of Prosthodontics
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• v.9 no.1
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• pp.41-45
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• 1969

A major disadvantage of Dental cements is their solubility. So it is very important to measure the exact amount of solubility to select clinically suitable materials. The most common laboratory test for solubility is the measurement of disintegration in distilled water, as outlined in A.D.A. Specifications 8 and 9, In addition to the possible factors influencing the solubility, the experiments were all conducted in compliance with A.D.A. Specifications. The solubility of 2 Zinc Phosphate cements and 1 Silicate cement in time of dissolution, concentration of solute in dissolving medium, and type of dissolving medium were investigated. The following results were obtained. 1. Generally the materials were more soluble in organic acids than in distilled water. 2. The dissolution cements tends be minimized by tests utilizing prolonged storage in the same media. 3. In Acetic acid solution, Zinc Phosphate cements were more soluble than Silicate cement, and in Citric acid solution both were markedly more soluble. 4. Solubility was increased by continually presenting fresh liquid, unsaturated with solute, to the cement-water interface.

• Environmental Engineering Research
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• v.14 no.2
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• pp.126-133
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• 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.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.165-173
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• 2004

Behavior of hazardous organic compounds including bisphenol A, phtalic acid, and phosphoric acid in low pressure nanofiltration process were investigated. In the case of NTR729HF, rejection of all target organic compounds except 2-H-Benzothiazol and 2-isopropyl phenol was more than 90%. The lowest rejection for 2-H-Benzothiazol was observed in another membranes. The UTC60 and UTC20 showed similar rejection characteristics of hazardous organic compounds. Although the rejection of Bisphenol A, n-buthyl benzenesulfoneamide, N-ethyl-p-toluensulfonamide, 2-H-benzothiazol, p-t-butylphenol and 2-isopropyl phenol was less than 30%, the rejection of tributyl phosphate, triethyl phosphate, camphor, 2,2,4 trimethyl 1,3 pentandiol and diphenyl amine was more than 90% in the case of UTC60 and UTC20. The rejection characteristics of various hazardous organic compounds were converted into one parameter Ks, which was proposed in the diffusion-convection model. The Ks of hazardous organic compounds were discussed by comparing with their solute size represented by Stokes radius. The diffusion convection model considering Ks was successful to interpret rejection characteristics of hazardous organic compounds by low-pressure nanofiltration membranes.