• KSBB Journal
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• v.21 no.3
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• pp.199-203
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• 2006

Precipitation and reactive distillation were employed to recover lactic acid from fermentation broth. Lime was initially added to fermentation broth in order to convert soluble lactic acid to an insoluble calcium lactate form. Drowning-out crystallization was used to decrease the solubility of calcium lactate by adding ethanol as a co-precipitant. In the ideal solution of organic acids as well as fermentation broth, precipitation experiments were performed with varying amounts of ethanol. Precipitation process was followed by reactive distillation. Carboxylate salts formed in the previous precipitation process were mixed with carbon dioxide and triethylamine to precipitate as calcium carbonate. The remaining liquid was distilled for 1 hr at different temperatures. Triethylamine and water were recovered from the top of the distiller, while organic acids, inducing lactic acid as a main component remained in feeding bottle. The yield of recovered lactic acid was 67.5% with the purity of 99.7%.

• Journal of the Korean Ceramic Society
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• v.24 no.1
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• pp.77-85
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• 1987

Hardened cement paste is mainly affected by corrosion of sulphate and chlorine ions in sea water. In this investigation, many specimens were made with the cement clinker minerals such as C3S, C3A, C4AF and their mixture according to cement composition added various blending materials. After the specimens were immersed in 4% MgSO4 and MgCl2 solutions, the product of reaction, the microstructure of specimen and Ca+2 ion leached in the solution were studied. The formation of Ca(OH)2 in the specimen of C3S is reduced relatively by adding pozzolanic admixtures. The chlorine ion is easily diffuse into the C3S specimen and produced CaCl2 compound, and it makes the specimen porous by leaching out itself into the solution. The specimen of C3A, C4AF are broken down by expanding reaction of ettringite and gypsum compound produced in the MgSO4 solution. At a later period, the ettringite is transformed into gypsum and 5MgO.2Al2O3·15H2O. The C3A in the MgCl2 solution combines chlorine ion to form Friedel's salt and prevents the diffusion reaction of chlorine ion into the specimen. Granulated slag shows inferior effect on the resistance of the specimen in MgSO4 solution by forming ettringite and gypsum, but good result in MgCl2 solution. Pozzolanic materials, on the whole, offer noticable effect on the resistance of the specimen in both solutions.

• Journal of Pharmaceutical Investigation
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• v.37 no.6
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• pp.349-354
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• 2007

For decades, the various virtues of ${\alpha}-lipoic$ acid (ALA), a natural material synthesized in most cells, have been intensively studied and proved. Recently it was reported that ALA caused significant bodyweight reduction via appetite suppression. Unfortunately, the efficacy requires an administration over 50 mg/kg. The low bioavailability and the short plasma half life of ALA lead us to explore novel pharmaceutical dosage forms using nanoparticles. In this study, the effect of polymeric stabilizers on the bioavailability improvement of ALA nanoparticles was investigated. The reduction of particle size via nano-comminution technology was successful resulting in volume average particle sizes of 320 - 340 nm. The in vitro release rate of ALA did not reflect the decrease of particle size, possibly because of the self polymerization of ALA during nano-comminution. The type of polymeric stabilizers could not affect the release rate either. However, the in vivo food intake results of ALA showed that nano-suspensions were more effective than microparticles or a salt form. The nano-suspension containing polyvinyl pyrrolidone as the primary stabilizer and polyacrylic acid as the secondary stabilizer showed more improved efficacy for 2 hours.

• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.2
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• pp.16-27
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• 2003

For the last decade, some 400 small and large oil spill accidents have occurred every year. Such accident blow a serious damage to the marine resource and ecosystem, which can't be estimated in terms of economic and environmental losses. The physical/chemical methods used currently may be effective at the initial stage of accidents, but they can't serve to remove the spilled oil completely. Moreover, the dispersant may lead to a secondary contamination detrimental to the lives inhabiting wet lands, beaches and tidal zone. Thus, a new decomposing technology Is required for the environmentally sensitive areas. Bioremediation is the active use of biological techniques to mitigate the consequences of a spill using biological processes and refers both of stimulation of pollutant biodegradation and/or to enhance ecosystem recovery Bioremediation is an economically attractive method for the clean-up of oil-contaminated area. Bioremediation has been demonstrated to be an effective oil spill countermeasure for use in cobble, sand beach, salt marsh, and mud flat environment.

• Journal of the Korean institute of surface engineering
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• v.50 no.5
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• pp.366-372
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• 2017

Plasma electrolytic oxidation(PEO) has attracted attention as a surface treatment which has high wear resistance and corrosion resistance. PEO is generally considered as cost-effective, environmentally friendly and superior in terms of coating performance. Most of studies about the PEO processes have been applied to light metals such as Al and Mg. Because the strength of Al and Mg is weaker than that of steel, there is a limit to the application. In this study, PEO process was used to form oxide coatings on Hot dipped aluminized(HDA) steel and the characteristics of the coating film according to the PEO current density were studied. The morphology was observed by SEM and component was analyzed by using EDS. The corrosion behaviors of PEO coating films were estimated by exposing salt spray test at 5 wt.% NaCl solution and measuring polarization curves in deaerated 3 wt.% NaCl solution. With the increase of PEO process current density, the pore size of the coating surface and the thickness of coating increased. It was confirmed that no Fe component was present on the coating surface. PEO coating films obviously showed good corrosion resistance compared with HDA. It is considered that the PEO coating acts as a barrier to protect the base material from external factors causing corrosion.

• Resources Recycling
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• v.25 no.5
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• pp.64-74
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• 2016

Titanium and iron are closely related in nature, although titanium is the ninth most abundant element in the Earth's crust. Iron in titanium ores must be removed for use as feedstocks in the manufacture of titanium dioxide pigments and pure $TiCl_4$ for metal titanium. In this study, various beneficiation processes of ilmenite for production of $TiO_2$ have been reviewed and compared. Most of these processes involve a combination of pyrometallurgy and hydrometallurgy. These beneficiation processes of ilmenite generate considerable quantities of wastes primarily in the form of iron salt, iron oxide and acidic effluents. Therefore, it is important that recovery of acid value from waste and conversion of iron bearing waste to useful materials for development of new beneficiation processes of ilmenite.

• Bulletin of the Korean Chemical Society
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• v.15 no.10
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• pp.857-860
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• 1994

We have calculated the ${\pi}$-electron density, atom self-polarizability, and free valence on each atom of N-(2-chlorobenzyl)-pyridinium, N-(benzyl)-2-chloropyridinium, and N-(2-chlorobenzyl)-2-chloropyridinium salts using a simple Huckel method in order to discuss their intramolecular photocyclization reaction in a qualitative method. Our calculation qualitatively predicts that photocyclization occurs through forming radicals as a reaction intermediate by breaking a C-Cl bond after photoexcitation into a triplet state via intersystem crossing from an initially excited singlet state. We noticed that this C-Cl bond breaking is aided by ${\pi}$-complex formation between a chlorine atom and the ${\pi}$ -electrons of the neighboring ring in the triplet state and a stronger ${\pi}$-complex bond makes C-Cl bond breaking, i.e., radical formation, much easier. A chlorine atom will form a stronger ${\pi}$ -complex bond to a benzyl ring of N-(benzyl)-2-chloropyridinium than a pyridinium ring of N-(2-chlorobenzyl)-pyridinium because the former can donate its ${\pi}$-electron more easily than the latter. The chlorine at position 15 of N-(2-chlorobenzyl)-2-chloropyridinium salt in the excited state also provides its ${\pi}$-electron to the benzyl ring. So this ${\pi}$-electron can increase the bond strength of the $\pi-complex.$ Therefore, the strength of ${\pi}$-complex follows the order of N-(2-chlorobenzyl)-2-chloropyridinium, N-(benzyl)-2-chloropyridinium, and N-(2-chlorobenzyl)-pyridinium salts and thus the radical formation rate. This provides us with an intramolecular photocyclization reaction rate of the same order as given above.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.2
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• pp.161-176
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• 2021

In this study, the electrochemical behavior of Sm on the binary liquid Al-Ga cathode in the LiCl-KCl molten salt system is investigated. First, the co-reduction process of Sm(III)-Al(III), Sm(III)-Ga(III), and Sm(III)-Ga(III)-Al(III) on the W electrode (inert) were studied using cyclic voltammetry (CV), square-wave voltammetry (SWV) and open circuit potential (OCP) methods, respectively. It was identified that Sm(III) can be co-reduced with Al(III) or Ga(III) to form Al_zSm_y or Ga_xSm_y intermetallic compounds. Subsequently, the under-potential deposition of Sm(III) at the Al, Ga, and Al-Ga active cathode was performed to confirm the formation of Sm-based intermetallic compounds. The X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analyses indicated that Ga₃Sm and Ga₆Sm intermetallic compounds were formed on the Mo grid electrode (inert) during the potentiostatic electrolysis in LiCl-KCl-SmCl₃-AlCl₃-GaCl₃ melt, while only Ga₆Sm intermetallic compound was generated on the Al-Ga alloy electrode during the galvanostatic electrolysis in LiCl-KCl-SmCl₃ melt. The electrolysis results revealed that the interaction between Sm and Ga was predominant in the Al-Ga alloy electrode, with Al only acting as an additive to lower the melting point.

• Mycobiology
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• v.47 no.2
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• pp.230-241
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• 2019

The Great Sebkha of Oran is a closed depression located in northwestern of Algeria. Despite the ranking of this sebkha among the wetlands of global importance by Ramsar Convention in 2002, no studies on the fungal community in this area have been carried out. In our study, samples were collected from two different regions. The first region is characterized by halophilic vegetation and cereal crops and the second by a total absence of vegetation. The isolated strains were identified morphologically then by molecular analysis. The biotechnological interest of the strains was evaluated by testing their ability to grow at different concentration of NaCl and to produce extracellular enzymes (i.e., lipase, amylase, protease, and cellulase) on solid medium. The results showed that the soil of sebkha is alkaline, with the exception of the soil of cereal crops that is neutral, and extremely saline. In this work, the species Gymnoascus halophilus, Trichoderma gamsii, the two phytopathogenic fungi, Fusarium brachygibbosum and Penicillium allii, and the teleomorphic form of P. longicatenatum observed for the first time in this species, were isolated for the first time in Algeria. The halotolerance test revealed that the majority of the isolated are halotolerant. Wallemia sp. and two strains of G. halophilus are the only obligate halophilic strains. All strains are capable to secrete at least one of the four tested enzymes. The most interesting species presenting the highest enzymatic index were Aspergillus sp. strain A4, Chaetomium sp. strain H1, P. vinaceum, G. halophilus, Wallemia sp. and Ustilago cynodontis.

• Korean Journal of Metals and Materials
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• v.48 no.1
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• pp.49-56
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• 2010

This study investigated how the surface of Al-12wt.%Si alloy modified by the plasma electrolytic oxidation process (PEO). The PEO process was performed in an electrolyte with sodium hexametaphsphate as a conducting salt, and the effect of ammonium metavanadate on variations in the morphology of electrochemically generated oxide layers on the alloy surface was investigated. It is difficult to form a uniform passive oxide layer on Al alloys with a high Si content due to the differences in the oxidation behavior of the silicon-rich phase and the aluminum-rich phase. The oxide layer covered the entire surface of the Al-12WT.%Si alloy uniformly when ammonium metavanadate was added to the electrolyte. The oxide layer was confirmed as a mixture of $V_2O_3$ and $V_2O_5$ by XPS analysis. In addition, the oxide layer obtained by the PEO process with ammonium metavanadate exhibited a black color. Application of this surface modification method is expected to solve the problem of the lack of uniformity in the coloring of oxide layeres caused by different oxidation behaviors during a surface treatment.