• Korean Chemical Engineering Research
• /
• v.43 no.4
• /
• pp.487-494
• /
• 2005

Nowadays a large amount of wastewater containing metal working fluids and cleaning agents is generated during the cleaning process of parts working in various industries of automobile, machine and metal, and electronics etc. In this study, aqueous or semi-aqueous cleaning wastewater contaminated with soluble or nonsoluble oils was treated using ultrafiltration system. And the membrane permeability flux and performance of oil-water separation (or COD removal efficiency) of the ultrafiltration system employing PAN as its membrane material were measured at various operating conditions with change of membrane pore sizes and soil concentrations of wastewater and examined their suitability for wastewater treatment contaminated with soluble or insoluble oil. As a result, in case of wastewater contaminated with soluble oil and aqueous or semi-aqueous cleaning agent, the membrane permeability increased rapidly even though COD removal efficiency was almost constant as 90 or 95％ as the membrane pore size increased from 10 kDa to 100 kDa. However, in case of the wastewater contaminated with nonsoluble oil and aqueous or semi-aqueous cleaning agent, as the membrane pore size increased from 10 kDa to 100 kDa and the soil concentration of wastewater increased, the membrane permeability was reduced rapidly while COD removal efficiency was almost constant. These phenomena explain that since the membrane material is hydrophilic PAN material, it blocks nonsoluble oil and reduces membrane permeability. Thus, it can be concluded that the aqueous or semi-aqueous cleaning solution contaminated with soluble oil can be treated by ultrafiltration system with the membrane of PAN material and its pore size of 100 kDa. Based on these basic experimental results, a pilot plant facility of ultrafiltration system with PAN material and 100 kDa pore size was designed, installed and operated in order to treat and recycle alkaline cleaning solution contaminated with deep drawing oil. As a result of its field application, the ultrafiltration system was able to separate aqueous cleaning solution and soluble oil effectively, and recycle them. Further more, it can increase life span of aqueous cleaning solution 12 times compared with the previous process.

• Microbiology and Biotechnology Letters
• /
• v.30 no.4
• /
• pp.352-358
• /
• 2002

An amylase that hydrolyzes starch into maltopentaose as a main product was found in the culture supernatant of a strain of Bacillus megaterium KSM B-404 isolated from local soil. The enzyme was purified 129-fold by ammonium sulfate precipitation, DEAE-Toyopearl and Superdex 75 HR 10/30 column using a FPLC system. The molecular weight of the amylase was determined as about 68 kDa by using SDS-PAGE. Optimum pH and temperature of amylase were found to be $50^{\circ}C$ and pH 6.0~7.0, respectively. The enzyme was stable up to $60^{\circ}C$ by addition of $Ca^{2+}$ and its pH stability was in the range of 6.0~10.0. The activity of enzyme was inhibited by $Cu^{2+}$ $Hg^{2+}$ , and $Fe^{3+}$ and maintained by $Ca^{2+}$ and $Mg^{2+}$ . EDTA and pCMB also showed inhibitory effect to the enzyme. TLC and HPLC analysis of the products of the enzyme reaction showed the presence of maltopentaose(52%), maltotriose (25%), maltose (11%), glucose, and maltotetraose in the starch hydrolysates.

• Polymer(Korea)
• /
• v.30 no.6
• /
• pp.568-571
• /
• 2006

Poly(vinyl alcohol) (PVA)/gelatin(GEL) blend membranes were prepared under a high electric field, and their swelling and ion permeation behaviors were investigated. For alkali metal salts such as LiCl, NaCl and KCl, the permeability coefficients were increased until the electric field of 10 kV due to the decreased tortuosity, whereas they were decreased over 10 kV owing to the increase of the degree of crystallinity. The swelling ratios of the blend membranes showed the minimum values at pH 6, while the permeability coefficients exhibited the maximum values at the same condition. The minimum swelling ratios result from the repulsion effect between charged groups in acidic or basic regions, and the maximum permeabilities result from Donnan exclusion effect in the same regions. Especially, the per-meability coefficient for KCl of the membrane increased steeply to five times at $40^{\circ}C$ than below $35^{\circ}C$.

• Journal of Life Science
• /
• v.14 no.2
• /
• pp.269-274
• /
• 2004

Using heterogeneous catalyst, esterification reaction of soybean oil (SBO) with methanol was investigated. Distributions of components in mixtures of soybean oil and methanol were measured at temperatures ranging from 40 to $65^{\circ}C$. Glycerine contents of reaction mixtures were measured for the different kinds of catalysts, such as NaOH, CaO, Ca(OH)$_2$, MgO, Mg(OH)$_2$, and Ba(OH)$_2$. Based on the measured glycerine concentrations, conversions of the reaction mixtures were calculated. The effects of dose of catalyst, cosolvent and reaction temperature on final conversion were examined. Solubility of methanol in soybean oil was substantially greater than that of soybean oil in methanol. When the esterification reaction of soybean oil was catalyzed by heterogeneous catalyst, final conversion was strongly dependent on the alkalinity of the heterogeneous catalyst, and increased with the alkalinity of the catalyst material. Hydroxides from the alkali metals were more effective than oxides, which actually had no catalytic effects. When Ca(OH)$_2$ was used for the esterification catalyst, maximum value of final conversion was measured at dose of 4%. The final conversion and reaction rate increased with reaction temperature, and showed substantial increment at reaction temperature of 5$0^{\circ}C$. When cosolvent, CHCl$_3$, was added into the reaction mixture of soybean oil which catalyzed by Ba(OH)$_2$, maximum value of final conversion was appeared at dose of 3%.

• Applied Chemistry for Engineering
• /
• v.21 no.1
• /
• pp.63-70
• /
• 2010

Transition metal based spent catalysts (Ni-Mo and Co-Mo), which were scrapped from the petrochemical industry, were reused for the removal processes of volatile organic compounds (VOCs). Especially the optimum regeneration procedures were determined using the removal efficiency of VOCs. In this work, the spent Ni-Mo and spent Co-Mo catalysts were pretreated with different physic-chemical treatment procedure: 1) acid aqueous solution, 2) alkali solution, 3) chemical agent and 4) steam. The various characterization methods of spent and its regenerated catalysts were performed using nitrogen adsorption, X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with an energy dispersive spectrometry (EDS). It was found that all spent catalysts were found to be potentially applicable catalysts for catalytic oxidation of benzene. The experimental results also indicated that among the employed physico-chemical pretreatment methods, the oxalic acid aqueous (0.1 N, $C_2H_2O_4$) pretreatment appeared to be the most efficient in increasing the catalytic activity, although the catalytic activity of spent Ni-Mo and spent Co-Mo catalysts in the oxidation of benzene were greatly dependent on the pretreatment conditions. The pretreated spent catalysts at optimum condition could be also applied for removing other aromatic compounds (Toluene/Xylene).

• Korean Journal of Agricultural Science
• /
• v.7 no.2
• /
• pp.182-189
• /
• 1980

This experiment was carried out to study on methods of processing the fruit base which is to be used for preparing the fruit yoghurts. Common fruits were compared and peach was chosen among them for this purpose by determing the rate of decrease in hardness during the process of cooking. The maturity, temperature of cooking and methods of peeling were tested to maintain the desirable hardness during the process, and the effects of metallic ion addition on the hardness of the flesh were also studied. The results obtained were as follows. 1. The peaches were keeping the most stable texture during cooking, among common fruits, however the hardness of apples were decreased markedly. Rate of decreases in the flesh hardness were high during the initial stages of cooking then slowered in all fruits tested. 2. Flesh hardness of the peaches were largely affected by the temperature of cooking. And the texture of freeze-stored fruits was severly damaged during thawing, so that could be used only for the limited purposes such as for stirred-type yoghurt. 3. Divalent matallic ions, especially calcium ion, were effective for supporting the flesh hardness of peaches during cooking. 4. The optimal concentration of calcium chloride addition was 0.3%, and this resulted in its final concentration in the product under the legal dosage without any subsquent changes in colour and flavor. 5. The effects of calcium chloride addition were greater in the froms of dices than in those of slices, and in overmature fleshs than in immature ones. 6. Treatment of calcium chloride by soaking the slices or dices of lye-peeled peaches in 0.3% solution was found to be adaptable for the practical process.

• KSBB Journal
• /
• v.14 no.4
• /
• pp.511-516
• /
• 1999

The effects of environmental and compositon factors, such as reaction time, metal ions, pH, agitation speed, the weight ratio of water to oil, and the weight of enzyme, on the hydrolysis of oils by Lipase-OF were investigated. In case of oils with low melting point, the optimum temperature of hydrolysis were the enzyme activity was maximum was 37$^{\circ}C$. However, when the melting temperature was higher than 4$0^{\circ}C$, the optimum temperature was around the fusion temperature. The activity of Lipase-OF decreased very rapidly with increase of temperature in the range of higher than 45$^{\circ}C$ and the activity perished above $65^{\circ}C$. The effect of agitation speed was investigated from 150 to 650 rpm. The hydrolysis of oils increased as the agitation speed increased up to 350 rpm, but it did not increase any more above 350 rpm. The weight ratio of water to oil was changed from 1 : 9 to 9 : 1 for the investigation of the effect on the hydrolusis. The weight ratio for maximum hydrolysis was 1 : 1. $Ca^{2+}\;and\;Mg^{2+}$ among various metal ions had some effect on the stimulation of hydrolysis. The optimum concentration of the ions was about 100ppm at which the hydrolysis increased, compared with that of distilled water, by 2 to 3%. The Optimum pH of Lipase-OF was 7. The hydrolysis decreased as the pH decreased as the pH decreased and also decreased as the pH increased. The content of enzyme affected the hydrolysis of oil. The hydrolysis increased with the content of Lipase-OF in the range of less than 0.013 wt% of substrate. However, the increase of hydrolysis with the content of Lipase-OF ceased above 0.013 wt%. The experiments investigating the effect of environmental and composition factors on the hydrolysis of oils showed that the optimum temperature was 37$^{\circ}C$, the pH 7, the concentration of $Ca^{2+}\;or\;Mg^{2+}$ 100 ppm, the agitation speed 350 rpm, the weight ratio of water to oil 1 : 1, and the content of Lipase-OF 0.013 wt% of substrate.

• Analytical Science and Technology
• /
• v.6 no.1
• /
• pp.29-37
• /
• 1993

Some new podands containing phenyl(B), benzyl(Bz), pyridine(Py), quinoline(Q) and naphthalene(Np) as end-groups, and oxygen(O) and sulfur(S) in ether chains as donor atoms have been synthesized. The univalent cation binding characteristics of these podands have been studied by NMR titration and solvent extraction. By NMR titration we have found that the most of podands form 1:1 complexes with $Ag^+$ ion. Especially, the substituted sulfur atoms in ether chains show the effects to enhance the stabilities. We also carried out the extractions of univalent cation picrates including alkaline metal, $Ag^+$, $Tl^+$ and $NH_4{^-}$ ions from aqueous to chloroform layer by using these podands. We found that the extractabilities of $Ag^+$ ion with the quinoline-containing podands such as, $Q_2O_4$, $Q_2O_5$ and $BQO_5$ were 86.8, 86.6 and 48.0% respectively, but the naphthalene-containing podands such as, $Np_2O_4$ and $Np_2O_5$ extracted quite small amount. Otherwise, in cases of $Bz_2O_3S_2$(89.4%), $B_2O_2S_2$(96.8%), $B_2O_3S_2$(58.9%), $Py_2O_2S_2$(58.8%), $Py_2O_3S_2$(42.1%), and $B_2O_4S$(15.0%), interestingly, $Bz_2O_3S_2$ which have sulfur atoms and benzyl groups showed the highest extraction selectivity for $Ag^+$ ion. This result seems due to not only the strong interaction of $Ag^+$ ion with sulfur donors according to the HSAB theory, but also the effective ${\pi}-{\pi}$ stacking interaction between two aromatic end-groups which is enhanced by the flexible methylene spacing group in benzyl groups instead of phenyl groups. The extraction coefficients gave the similar tendency as the extractabilities and the stabilities. From these results, it could be concluded that the predominant factor affected to extraction coefficients is the stabilities, which are strongly influenced by the structures of podands.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.1
• /
• pp.35-41
• /
• 2006

Antibacterial activities of the trace elements in combination with the food additives were measured against 6 kinds of food-borne microorganisms such as Escherichia coli, Vibrio parahaemolyticus, Staphylococcus aureus, Bacillus cereus, Bacillus subtilis and Pseudomonas fluorescens. The difference of antibacterial activity was not shown among the kinds of food additives, such as dextrin, gelatin and collagen. Zn and Ge in combination with food additives had strong antibacterial effect. Especially, $1\%$ zinc acetate in combination with $1\%$ gelatin was more effective against P. fluorescens and S. aureus than against Bacillus sp., E. coli and V. parahaemolyticus. Minimum inhibitory concentration of zinc acetate in combination with $1\%$ gelatin appeared to be 0.5 mg/mL on S. aureus and P. fluorescens, and 1.0 mg/mL on E. coli, V. parahaemolyticus, B. cereus and B. subtilis. Minimum bactericidal concentration of zinc acetate in combination with $1\%$ gelatin appeared to be 0.5 mg/mL on P. fluorescens and 1.0 mg/mL on E. coli, V. parahaemolyticus, S. aureus, B. cereus and B. subtilis. The zinc acetate in combination with gelatin showed stronger inhibitory effect in acidic range below pH 6.0, and remained active even after heat treatment at $121^{\circ}C$ for 15 min. In comparison with control, the viable cell counts of fish pastes, which were coated with the solution containing both $1\%$ zinc acetate and $3\%$ gelatin, were decreased by more than 100-fold until the storage of 7 days at $10^{\circ}C$. The results indicate that the combined use of zinc acetate and some food additives could prolong the shelf life of fish pastes by 8 days or more at $10^{\circ}C$.

• Economic and Environmental Geology
• /
• v.50 no.5
• /
• pp.341-352
• /
• 2017

Along with Cs-137 (half-life: 30.17 years), Sr-90 (half-life: 28.8 years) is one of the most important environmental monitoring radioactive elements. Rapid and easy monitoring method for Sr-90 using Laser-Induced Breakdown Spectroscopy (LIBS) has been studied. Strontium belongs to a bivalent alkaline earth metal such as calcium and has similar electron arrangement and size. Due to these similar chemical properties, it can easily enter into the human body through the food chain via water, soil, and crops when leaked into the environment. In addition, it is immersed into the bone at the case of human influx and causes the toxicity for a long time (biological half-life: about 50 years). It is a very reductive and related with the specific reaction that makes wet analysis difficult. In particular, radioactive strontium should be monitored by nuclear power plants but it is very difficult to be analysed from high-cost problems as well as low accuracy of analysis due to complicated analysis procedures, expensive analysis equipment, and a pretreatment process of using massive chemicals. Therefore, we introduce the Laser-Induced Breakdown Spectroscopy (LIBS) analysis method that analyzes the elements in the sample using the inherent spectrum by generating plasma on the sample using pulse energy, and it can be analyzed in a few seconds without preprocessing. A variety of analytical plates for samples were developed to improve the analytical sensitivity by optimizing the laser, wavelength, and time resolution. This can be effectively applied to real-time monitoring of radioactive wastewater discharged from a nuclear power plant, and furthermore, it can be applied as an emergency monitoring means such as possible future accidents at a nuclear power plants.