• Resources Recycling
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• v.9 no.3
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• pp.13-21
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• 2000

This study describes to analyze the heat transfer characteristics of waste solvent recovery system using a double pipe heat exchanger heating solvent by the hot oil. The solvent recovery system consists of the feeding pump, the double pipe heat exchanger, the vacuum spray chamber, and the condenser. A double pipe heat exchanger consists of the first section to conduct the heating of solvent to the thermal saturated point and the second section to evaporate the saturated solvent. The heat transfer area for vaporization of water, benzene and alkylbenzene was predicted by the heat balance modelling and experimentally measured from the temperature distribution as a function of solvent flow rate and heating temperature. The required heat transfer area for vaporization was increased with increasing solvent flow rates and with decreasing heating temperatures due to decreased quantity of transferred heat per the unit area. Theoretical modelling of the heat transfer area for solvents vaporization in the pipe showed good agreement with experimental results. Results showed to be suitable for the waste solvent recovery using a double pipe heat exchanger.

• Mass Spectrometry Letters
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• v.14 no.2
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• pp.36-41
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• 2023

A simple method was developed to determine residual p-arsanilic acid (ASA), an organo-arsenic compound used as a feed additive, in aquatic products (eel, halibut, and shrimp) using EDTA-assisted solvent extraction and LC-MRM. The method was successfully validated in terms of specificity, linearity (coefficient of determination ≥ 0.995), accuracy (recovery or R, 72.72-78.73%), precision (the relative standard deviation of R, 2.08-6.98%), and sensitivity (the lower limit of quantitation, 5 ppb) according to CODEX guidelines (CAC-GL 71-2009). The use of EDTA in the extraction solvent and water with a suitable pH modifier as the reconstitution solvent may be the key factors for successful results. This is the first method that can be used for monitoring residual ASA in aquatic products using LC-MRM and could contribute to establishing a better aquatic product safety management system.

• Membrane and Water Treatment
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• v.4 no.2
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• pp.95-108
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• 2013

Metal ions exist in seawater, groundwater and industrial wastewaters. These source waters can be recycled if their concentrations are reduced. A number of processes can be applied for this purpose. Liquid-liquid extraction is one of the promising methods. In this paper, experimental results are presented on the removal of Cr(VI) using Aliquat-336, a reactive carrier, in sunflower oil (a non-toxic solvent). The performance of this new system is compared with those of kerosene (a toxic solvent). The extent of removal of Cr(VI) from samples with high and low concentrations are presented. The process was upgraded to a bench-scale module that can selectively remove about 50-90% Cr(VI) from samples of groundwater. Thus this process can produce water within the acceptable range for recycling and for use in secondary purposes such as irrigation.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.04a
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• pp.22-24
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• 1998

1. INTRODUCTION : The phase inversion method is widely used to prepare a variety of polymeric membranes ranging from micro-filtration to gas separation. The final morphology obtained by immersion precipitation strongly reflects the thermodynamics and kinetics of the system involved. The equilibrium thermodynamics of the ternary system of polymer/solvent/ nonsolvent is still very important to understand and predict membrane structure. Polysulfone (PSf) and polyethersulfone (PES) are important polymers as membrane materials due to the chemical resistance, mechanical strength, thermal stability and transport properies. There are several reports on the experimental phase diagrams in ternary mixtures of PSf/solvent/nonsolvent, and PES/solvent/nonsolvent. It would be interesting to investigate the solution thermodynamics containing these two polymers since PES is slightly less hyclrophobic than PSf.

• Composites Research
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• v.35 no.1
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• pp.18-22
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• 2022

Dispersion is one of the most important factors in the manufacture of composite materials. In the manufacture of composite materials, solvents are used to better disperse the reinforcement, nano-filler in the matrix. Since dispersion is affected with solvents, it is necessary to study which solvent is adopted to get good dispersion. In this study, the dispersion behavior and solubility of graphene oxide(GO) were examined under various solvents (DMF, NMP, ethylene glycol, Acetone, DI water) to identify dispersion. As a result of UV-Vis spectroscopy absorbance measurement, it was found that DMF and ethylene glycol had the best dispersibility, whereas DI water showed the lowest dispersibility. In addition, as a result of visually observing the dispersion according to the surface tension and time, it was found that the dispersibility was excellent in the order of DI water, ethylene glycol, NMP, DMF, and acetone, which was consistent with the Hansen solubility parameter value.

• Korean Journal of Microbiology
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• v.33 no.3
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• pp.181-186
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• 1997

Sugar ester compounds were synthesized in organic solvent using lipase. Anhydrous pyridinc was selected as ;I solvent because of reasonable solubility of sugar. The synthesis of sugar ester compound was catalyzed by Pseudomonas sp. lipase in the reaction system containing anhydrous pyridine as .i solvent and vinyl butylate as an acyl donor. The analysis of the reaction product by TLC and GC showed thilt monobutyryl and dibutyryl fructose esters were synthesized by transesterification reaction between fructose and vinyl butyrate. Optimal conditions for the transesterification reaction were as follows: the ratio of fructoselvinyl butylate, I : lO(M : M): reaction temperature, 40^{\circ}C.$, velocity of shaking, 150 rprn: concentration of enzyme, 10 mglml. The longer the reaction period, the higher the conversion rate, and the conversion rate reached up to 90% after about 10 days of reaction. Monobutyryl fructose was mainly synthesized in the early stage of reaction, but the amount of dibutyryl fructose increased gradually as the rcdction progressed. When a small amount of water was added to the reaction mixture (micro-water system), the reaction rate decreased, while that of rnonobutyr~l fructosc increased. Only monobutyryl fructose was obtained when 1% water was added to the reaction mixture.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.6
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• pp.815-822
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• 1993

This experiment was carried out to determine the separation condition of 1-dimethylaminonaphthalene-5-sulfony(Dansyl) derivatives of amino acids by reverse-phase high performance liquid chromatography with Nova-Pak C18 column. Determined solvent system was solvent A(200mA phosphate buffer pH 6.8 15%, acetonitrile 11%, water 74%) and solvent B(acetonitrile 65%, methanol 28%, water 7%). Linear gradient of solvent B was applied from 12% to 80% for 50min. Complete separation of 20 amino acids including asparagine and glutamine which constitute protein was achieved within 50min. As the detection limit was the range of picomole, the resolution power was excellent. Reproducibility of the retention time was less than mean $\pm$0.05min. According to the above optimum chromatographic conditions, the amino acid composition of some food and human blood was examined. The most affluent amino acid was alanine in human blood, aspartic acid and glutamic acid in soy sauce, alanine and threonine in soy milk and proline in milk and yoghurt.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.420-426
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• 2017

Recently, solvent-resistant nanofiltration membranes have been studied for the separation of solvents or solutes using a molecular weight cut-off system of the polymer which is resistant to a specific solvent. Required conditions for these membranes must have are excellent physical properties and solvent resistance. Polybenzimidazole, which is known to be one of the most heat-resistant commercially available polymers, has an excellent inherent solvent resistance and it is even insoluble in stronger organic solvents when cross-linked. Therefore, in this study, the applicability of polybenzimidazole as a solvent resistant nanofiltration membrane was discussed. The membrane was fabricated using the non-solvent induced phase separation method and showed a suitable morphology as a nanofiltration membrane confirmed by field emission scanning electron microscopy. In addition, the permeance of the solvent in the presence or absence of cross-linking was investigated and the stability was also confirmed through long operation. The permeance test was carried out with five different solvents: water, ethanol, benzene, N, N-dimethylacetamide (DMAc) and n-methyl-2-pyrrolidone (NMP); each of the initial flux was $6500L/m^2h$ (water, 2 bar), $720L/m^2h$ (DMAc, 5 bar), $185L/m^2h$ (benzene, 5 bar), $132L/m^2h$ (NMP, 5 bar), $65L/m^2h$ (ethanol, 5 bar) and the pressure between 2 and 5 bar was applied depending on the type of membrane.

• Journal of Microbiology and Biotechnology
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• v.10 no.1
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• pp.99-102
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• 2000

To establish optimal conditions for esterification by Candida cylindracea, lipase reactions were performed simultaneously, separately, or individually in the varying initial rates of $0.014-0.060\mu$mole free fatty acids consumed min-1g-1. The reactants which were conditioned at aw of 0.12 gave the highest initial rate of esterifying $0.060\mu$mole free fatty acids consumed min-1g-1. These results suggest that the esterifying activity of lipase in an organic system depends on the transfer of available water within the reaction system.

• KSBB Journal
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• v.6 no.3
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• pp.281-288
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• 1991

This research was carried to investigate the effects of several organic solvents on the enzymatic transphosphatidylation in emulsion and two-phase solvent systems. The solvents having a similar dielectric constant with diethylether were effective for the enzyme activity. Diethylether and butylacetate were the most effective solvents, when added 12-15%(v/v) and 10-40%(v/v), respectively, for the synthesis of phosphatidylglycerol, phosphatidylethyleneglycol and phosphatidylpropyleneglycol. In the emulsion system, the size of ovolecithin liposome was increased and the clearness of the phospholipid bilayer was reduced as increasing the diethylether concentration. In the twophase solvent system, the rapidest reaction was obtained when water-organic solvent ratio was close to 1. The ratio of aqueous phase. however, should be lowered to 37% to gain the sole product of transphosphatidy1ation, without phosphatidohydrolysis.