• Membrane and Water Treatment
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• v.5 no.3
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• pp.207-219
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• 2014

Fouling is one of the critical factors associated with the application of membrane technology in treating palm oil mill effluent (POME), due to the presence of high concentration of solid organic matter, oil, and grease. In order to overcome this, chemical cleaning is needed to enhance the effectiveness of membranes for filtration. The potential use of sodium hydroxide (NaOH), sodium chloride (NaCl), hydrochloric acid (HCl), ethylenediaminetetraacetic acid (EDTA), and ultrapure water (UPW) as cleaning agents have been investigated in this study. It was found that sodium hydroxide is the most powerful cleaning agent, the optimum conditions that apply are as follows: 3% for the concentration of NaOH, $45^{\circ}C$ for temperature solution, 5 bar operating pressure, and solution pH 11.64. Overall, flux recovery reached 99.5%. SEM images demonstrated that the membrane surface after cleaning demonstrated similar performance to fresh membranes. This is indicative of the fact that NaOH solution is capable of removing almost all of the foulants from PES membranes.

• Korean Journal of Materials Research
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• v.20 no.3
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• pp.111-116
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• 2010

Chloride-based fluxes such as NaCl-KCl are used in the refining of Al melt. The vapor pressure of the chloride is one of the fundamental pieces of information required for such processes, and is generally high at elevated temperatures. In order to measure the vapor pressure for chlorides, the apparatus for the transpiration method was assembled in the present study. The vapor pressure of $ZnCl_2$ and $FeCl_2$, which is related with the process of aluminum refining and the recovery of useful elements from iron and steel industry by-products, was also measured. In the measurement of vapor pressure by the transpiration method, the powder of $ZnCl_2$ or $FeCl_2$ in a alumina boat was loaded in the uniform zone of the furnace with a stream of Ar. The weight loss of $ZnCl_2$ and $FeCl_2$ after holding was measured by changing the flow rate of Ar gas (10 sccm -230 sccm), and the partial pressures of $ZnCl_2$ and $FeCl_2$ were calculated. The partial pressures within a certain range were found to be independent of the flow rate of Ar at different temperatures. The vapor pressures were measured in the temperature range of 758-901K for $ZnCl_2$ and 963-983K for $FeCl_2$. The measured results agreed well with those in the literature.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.2
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• pp.209-229
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• 2022

This work provided a review of three techniques-(1) spectrochemical, (2) electrochemical, and (3) spectroelectrochemical-for molten salt medias. A spectroelectrochemical system was designed by utilizing this information. Here, we designed a spectroelectrochemical cell (SEC) and calibrated temperature controllers, and performed initial tests to explore the system's capability limit. There were several issues and a redesign of the cell was accomplished. The modification of the design allowed us to assemble, align the system with the light sources, and successfully transferred the setup inside a controlled environment. A preliminary run was executed to obtain transmission and absorption background of NaCl-CaCl₂ salt at 600℃. It shows that the quartz cuvette has high transmittance effects across all wavelengths and there were lower transmittance effects at the lower wavelength in the molten salt media. Despite a successful initial run, the quartz vessel was mated to the inner cavity of the SEC body. Moreover, there was shearing in the patch cord which resulted in damage to the fiber optic cable, deterioration of the SEC, corrosion in the connection of the cell body, and fiber optic damage. The next generation of the SEC should attach a high temperature fiber optic patch cords without introducing internal mechanical stress to the patch cord body. In addition, MACOR should be used as the cell body materials to prevent corrosion of the surface and avoid the mating issue and a use of an adapter from a manufacturer that combines the free beam to a fiber optic cable should be incorporated in the future design.

• Korean Journal of Environmental Agriculture
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• v.13 no.2
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• pp.183-190
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• 1994

To assess the effects of plant stress by light, temperature, NaCl and soil moisture on photosynthetic activity, the fluorescence method was used for Chinese cabbage(Brassica perkinensis Rupr.), strawberry(Fragaria grandiflora Ehrh.) and citrus tree(Citrus unshiu Marc.). With decreasing the light intensity, Fv/Fm ratios of intact leaves of Chinese cabbage and strawberry increased significantly, indicating lower photochemical efficiency in PS II system, resulting in an inverse relationship with the photosynthetic activity. Chinese cabbage and strawberry that were grown at higher temperature had higher Fv/Fm ratios and photosynthetic activities, while those given high concentration of NaCl and having low soil moisture had lower values. Chinese cabbage more resistant to salt stress and requiring more water had a greater Fv/Fm ratio than strawberry. In citrus tree, Fv/Fm ratio was lower in the non-irrigated group than the irrigated one. From these results, the fluorescence method was found to be a useful tool which can be used to assess the degree of in vivo stress induced by various environmental factors.

• Korean Journal of Microbiology
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• v.33 no.2
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• pp.142-148
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• 1997

Mrthylov~orits sp. starin SSl, a restricted facultative methylotrophic bacterium. growing on methanol was found to produce small amount of extracellular polysaccharide (EPS) under the optimal growth conditions, while it produced large amount of the polysaccharide under nitrogen limihtion. The optimal ratio of carbon to nitrogen for EPS production were found to be 5.2. The optimal temperature and pH for EPS production were 30^{\circ}C.$ and 6.5, spectively. The EPS consisted of carbohydrate, protein and small amount pyruvic acid. The reducing sugars in the EPS consisted mainly of glucose and a small amount of mannose. The EP!; treated with ethanol (EPSae) was found to have several properties different from those of the EPS which was not treated with ethanol (EPSbe); the EPSae contained no pyruvic acid. It also contained less protein and showed much lower viscosity than the EPSbe. The viscosity of EPSbe was very sensitive to NaCl and decreased t;harply upon exposure of the polysaccharide to even 0.5% (wiv) NaCl solution. The viscosity, however, was increased irreversibly upon exposure of the saccharide to high temperature. The molecular weight of EPS was estimiited to be $2.5{\times}$10^6$ - $3.5{\times}*$10^6$ using Sepharose hB column chromatography. Scanning electron microscopy revealed that the lyophilized EPSbe and EPSae have a structure of thread-like fibers and a mesh-like structure resembling bee-hive, respectively.

• Korean Journal of Materials Research
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• v.25 no.12
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• pp.659-665
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• 2015

The self-propagating high temperature synthesis approach was applied to synthesize amorphous boron nano-powders in argon atmospheres. For this purpose, we investigated the characteristics of a thermally induced combustion wave in the $B_2O_3+{\alpha}Mg$ system(${\alpha}=1.0-8.0$) in an argon atmospheres. In this study, the exothermic nature of the $B_2O_3-Mg$ reaction was investigated using thermodynamic calculations. Experimental study was conducted based on the calculation data and the SHS products consisting of crystalline boron and other compounds were obtained starting with a different initial molar ratio of Mg. It was found that the $B_2O_3$ and Mg reaction system produced a high combustion temperature with a rapid combustion reaction. In order to regulate the combustion reaction, NaCl, $Na_2B_4O_7$ and $H_3BO_3$ additives were investigated as diluents. In an experimental study, it was found that all diluents effectively stabilized the reaction regime. The final product of the $B_2O_3+{\alpha}Mg$ system with 0.5 mole $Na_2B_4O_7$ was identified to be amorphous boron nano-powders(< 100 nm).

• Journal of the Korea Concrete Institute
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• v.26 no.1
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• pp.71-78
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• 2014

The long term integrity of concrete cask is very important for spent nuclear fuel dry storage system. However, there are serious concerns about early deterioration of concrete cask from creaking and corrosion of reinforcing steel by chloride ion because the cask is usually located in seaside, expecially by combined deterioration such as chloride ion and heat, carbonation. This study is to investigate the relation between temperature and chloride ion diffusion of concrete. Immersion tests using 3.5% NaCl solution that were controlled in four level of temperature, i.e. 20, 40, 65, and $90^{\circ}C$, were conducted for four months. The chloride ion diffusion coefficient of concrete was predicted based on the results of profiles of Cl- ion concentration with the depth direction of concrete specimens using the method of potentiometric titration by $AgNO_3$. Test results indicate that the diffusion coefficient of chloride ion increases remarkably with increasing temperature, and there was a linear relation between the natural logarithm values of the diffusion coefficients and the reciprocal of the temperature from the Arrhenius plots. Activation energy of concrete in this study was about 46.6 (W/C = 40%), 41.7 (W/C = 50%), 30.7 (W/C = 60%) kJ/mol under a temperature of up to $90^{\circ}C$, and concrete with lower water-cement ratio has a tendency towards having higher temperature dependency.

• Journal of Microbiology and Biotechnology
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• v.31 no.5
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• pp.710-716
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• 2021

A risk analysis of Shiga toxin (Stx)-encoding bacteriophage was carried out by confirming the transduction phage to non-Stx-producing Escherichia coli (STEC) and subsequent expression of the Shiga toxin genes. The virulence factor stx1 was identified in five phages, and both stx1 and stx2 were found in four phages from a total of 19 phage isolates with seven non-O157 STEC strains. The four phages, designated as ϕNOEC41, ϕNOEC46, ϕNOEC47, and ϕNOEC49, belonged morphologically to the Myoviridae family. The stabilities of these phages to temperature, pH, ethanol, and NaClO were high with some variabilities among the phages. The infection of five non-STEC strains by nine Stx-encoding phages occurred at a rate of approximately 40%. Non-STEC strains were transduced by Stx-encoding phage to become lysogenic strains, and seven convertant strains had stx1 and/or stx2 genes. Only the stx1 gene was transferred to the receptor strains without any deletion. Gene expression of a convertant having both stx1 and stx2 genes was confirmed to be up to 32 times higher for Stx1 in 6% NaCl osmotic media and twice for Stx2 in 4% NaCl media, compared with expression in low-salt environments. Therefore, a new risk might arise from the transfer of pathogenic genes from Stx-encoding phages to otherwise harmless hosts. Without adequate sterilization of food exposed to various environments, there is a possibility that the toxicity of the phages might increase.

• Journal of Navigation and Port Research
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• v.37 no.2
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• pp.129-135
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• 2013

Recently, waste water treatment system is developed in small and middle size to get more economic advantage. Freeze concentration system has high thermodynamic efficiency and low energy consumption, can re-use purified water and cold energy obtained from ice. This study was experimentally performed to investigate pollution containment in frozen layer by cooling wall temperature, air-bubble flow methods, initial ice-lining thickness of frozen layer in NaCl aqueous solution and the representative heavy metals, Pb and Cr aqueous solution. As the result, a decrease in the cooling wall temperature bring a higher growth rate of ice front and the more solute was involved in frozen layer. The method to inject directly air-bubble into ice-liquid interface through ring shape nozzle gave high purity of ice compared to indirect method. Ice lining in 5mm thickness resulted in frozen layer with higher purity than 1mm thickness.

• Journal of the Mineralogical Society of Korea
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• v.20 no.1 s.51
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• pp.7-19
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• 2007

Four types of fluid inclusions are trapped within tourmaline from Daeyou pegmatite, Jangsu-Gun, Jeonllabukdo. They range $5{\sim}100\;{\mu}m$ in size and are grouped into I, II, III, and IV based on the phase behavior at the room temperature: (1) Type I inclusions are liquid-rich and NaCl equivalent salinity ranged $0{\sim}12\;wt%$, and the homogenization temperatures (Th) ranged $181{\sim}230^{\circ}C$ with eutectic temperatures (Te) $-54{\sim}-22^{\circ}C$. (2) Type II inclusions are vapor-rich and salinity ranged $3{\sim}8\;wt%$ NaCl, and Th ranged $177{\sim}304^{\circ}C$ also showing Te $-54{\sim}-29^{\circ}C$. (3) Type III inclusions contain a halite daughter mineral with $31{\sim}40\;wt%$ NaCl, Th $230{\sim}328^{\circ}C$. More than 90% of Type III homogenize by halite dissolution and are spatially associated with silicate melt inclusions. (4) Type IV inclusions are $CO_{2}$-bearing containing various daughter minerals such as sylvite and/or halite. The density of $CO_{2}$ system within the Type IV is $0.80{\sim}0.75\;g/cm^{3}$, Th $190{\sim}317^{\circ}C$, and salinity $2{\sim}35\;wt%$ NaCl. Type III fluid inclusions, considered as the earliest fluid, formed from the fluid exsolved from the crystallizing pegmatite. It is suggested that Type II fluid in the central part of tourmaline were exsolved earlier than Type I fluids in the margin indicating salinity fluctuation during the growth of tourmaline. It implies the fluctuation of the pressure since the salinity of fluid exsolved from the crystallizing melt is governed by the pressure. The last fluid was Type IV, which may be derived from the nearby limestone and metasedimentary rocks. It is suggested that Daeyou pegmatite containing muscovite without miarolitic cavities was formed by the partial melting resulted from the regional metamorphism. Subsequently, the exsolving fluids from the crystallizing melt were trapped in tourmaline at high pressure condition. The exsolved fluids contain various components such as $CaCl_{2}\;and\;MgCl_{2}$ as well as NaCl and KCl. The exsolution began at least at $2.7{\sim}5.3\;kbar\;and\;230{\sim}328^{\circ}C$ with the pressure fluctuation.