• KSBB Journal
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• v.15 no.4
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• pp.352-358
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• 2000

Preparation for the simplified separation of chitosandoligosaccharides from enzymatic hydrolysate was investigated. Two different types of chitosan beads as substrate were prepared as organic-based bead by W/O emulsion method and water-based bead by alkaline treatement. The average size of organic-based bead was $200{\mu}m$, and that of water based beads were $4000{\mu}m$, $100{\mu}m$, $30{\mu}m$, in diameter respectively. Enzyme stability was maintained over 80% at PH 6 after 24 hours. The optimal condition for the production of chitosanoligosaccharides was at pH 6.0, $50^{\circ}C$ and 40U (200U/g-chitosan) According to final oligosaccharide concentration water-based bed showed the similar result with that of organic-based bead even through it had smaller surface area attacked by chitosanse than that of organic-based bead. It is probable that the structure of water-based chitosan bead was looser than that of organic-based bead so enzyme penetrated easily into the bead structure. For the oligosaccharide production versus surface area the different size of water-based beads was investigated, Maxiaml production yield was observed in the $30{\mu}m$ beads. Consequently the water-based chitosan bead was better than the organic-based bead in this reaction system.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.251.2-251.2
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• 2010

Plant biomass has been proposed to be an alternative source for petroleum-based chemical compounds. Especially, phenolic chemical compounds can be obtained from lignin by chemical depolymerization processes because lignin consists of complex aromatic polymer such as trans-p-coumaryl, coniferyl and sinapyl alcohols, etc. Phenolic chemical compounds from lignin were usually produced in super critical water. However, we applied Near-critical water (NCW) system because NCW is known as a good solvent for lignin depolymerization. Organic matter like lignin can be solved in NCW system and the system has a unique acid-base property without conventional non-eco-friendly chemicals such as sulfuric acid and sodium hydroxide. In this work, we tried to optimize the NCW depolymerization system by adjusting the processing variables such as reaction time, temperature and pressure. Moreover, the amount of additional phenol was optimized by changing the molar ratio between water and phenol. Phenol was used as capping agent to prevent re-polymerization of active fragment such as formaldehyde. Alkali-lignin was used as a starting material and characterized by a Solid State 13C-NMR, FT-IR and EA (Elemental Analysis). GC-MS analysis confirmed that o-cresol, p-cresol, anisole and 4-hydroxyphathalic acid were the main product and they were quantitatively analyzed by HPLC.

• YAKHAK HOEJI
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• v.27 no.4
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• pp.303-307
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• 1983

Pipethanate*HCl reacts with ammonium cobaltothiocyanate to form a stable ion pair which has an absorption maximum at 626nm. The reaction product was insoluble in water but freely soluble in most organic solvents. 1, 2-Dichloroethane was the best extracting solvent among the several organic solvents. Pipethanate*HCl can be determined not only by the spectrophotometry but also inderectly by estimation of cobalt in the organic phase by atomic absorption spectrophotometry. Linear relationship was found between absorbance and concentration in the range of $1.0{\times}10^{-3}~4.0{\times}10^{-3}M$ by spectrophotometry and $1.5{\times}10^{-4}~4.0{\times}10^{-4}M$ by atomic absorption spectrophotometry. With this method it was possible to determine pipethanate$\cdot$HCl in the pharmaceutical preparations.

• Membrane Journal
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• v.6 no.2
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• pp.101-108
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• 1996

The oxidation/degradation efficiency of formic acid through the photoelectrochemical reaction has been investigated as a basic research in order to develope the process for degrading toxic organic compounds dissolved in water. A $TiO_{2}$ photoelectro-membrane reactor for purification of water, in which filtration as well as photoelectrocatalytic oxidation of organic compounds could be carried out simultaneously, was developed. Porous $SnO_{2}$ tubes prepared by slip casting and commercial porous stainless steel tubes, being electrically conductive, were used as not only supports but also working electrodes. The UV light with the wavelength of 365 nm was applied as a light source for photocatalytic reactions. The photoelectrocatatytic composite membranes were prepared by coating the support surface with the $TiO_{2}$ sol of pH 1.45. The oxidation efficiency of formic acid increased with the reaction time and the applied voltage, but was almost independent of the solution flux. The results showed that more than 90% of formic acid could he dograded at 27V using the $TiO_{2}$/stainless steel composite membrane, while about 77% in case of the $TiO_{2}/SnO_{2}$ Composite membrane. It was also concluded that the oxidation efficiencies of formic acid could be significantly improved by about 6~7 times by the photoelectrochemical reaction in comparison with those by the photocatalytic reaction only.

• Environmental Engineering Research
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• v.23 no.4
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• pp.345-353
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• 2018

This paper summarizes results of research on the electrochemical (EC) degradation of disinfection by-products (DBPs) and iodine-containing contrast media (ICMs), with the focus on EC reductive dehalogenation. The efficiency of EC dehalogenation of DBPs increases with the number of halogen atoms in an individual DBP species. EC reductive cleavage of bromine from parent DBPs is faster than that of chlorine. EC data and quantum chemical modeling indicate that the EC reduction of iodine-containing DBPs (I-DBPs) is characterized by the formation of active iodine that reacts with the organic substrate. The occurrence of ICMs has attracted attention due to their association with the generation of I-DBPs. Indirect EC oxidation of ICMs using anodes that produce reactive oxygen species can result in a complete degradation of these compounds yet I-DBPs are formed in the process. Reductive EC deiodination of ICMs is rapid and its overall rate is diffusion-controlled yet I-DBPs are also produced in this reaction. Further progress in practically feasible EC methods to remove DBPs, ICMs and other trace-level organic contaminants requires the development of novel electrocatalytic materials, elimination of mass transfer limitations via innovative design of 3D electrodes and EC reactors, and further progress in the understanding of intrinsic mechanisms of EC reactions of DBPs and TrOC at EC interfaces.

• Journal of the Korean Geosynthetics Society
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• v.22 no.4
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• pp.35-42
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• 2023

This paper described the strength variation characteristics to evaluate the applicability of a reactive material that can absorb organic pollutants as an underground barrier. The Strength was evaluated by unconfined compression test. The test results showed that the strength of the reactive material according to the absorption of each pollutant was in the order of water > TCE > TPH. However, the strength of the reactive material absorbing TPH was greater than that of the case absorbing TCE, when the composition ratio of polynorbornene was 12% or less. The strength of the reaction material in contact with water continued to decrease as the polynorbornene composition ratio decreased. The strength of the reaction material in contact with TCE and TPH increased as the polynorbornene composition ratio decreased from 30% to 21%, and then decreased. In other words, the optimal composition ratio of the reactive material should be applied considering the strength due to contact with pollutants according to the stress conditions occurring in the ground.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2577-2582
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• 2013

A novel stick-shaped portable sensing device featuring a microhole array interface between the polyvinylchloride-2-nitrophenyloctylether (PVC-NPOE) gel and water phase was developed for in-situ sensing of perchlorate ions in real water samples. Perchlorate sensitive sensing responses were obtained based on measuring the current changes with respect to the assisted transfer reaction of perchlorate ions by a perchlorate selective ligand namely, bis(dibenzoylmethanato)Ni(II) (Ni(DBM)2) across the polarized microhole array interface. Cyclic voltammetry was used to characterize the assisted transfer reaction of perchlorate ions by the $Ni(DBM)_2$ ligand when using the portable sensing device. The current response for the transfer of perchlorate anions by $Ni(DBM)_2$ across the micro-water/gel interface linearly increased as a function of the perchlorate ion concentration. The technique of differential pulse stripping voltammetry was also utilized to improve the sensitivity of the perchlorate anion detection down to 10 ppb. This was acquired by preconcentrating perchlorate anions in the gel layer by means of holding the ion transfer potential at 0 mV (vs. Ag/AgCl) for 30 s followed by stripping the complexed perchlorate ion with the ligand. The effect of various potential interfering anions on the perchlorate sensor was also investigated and showed an excellent selectivity over $Br^-$, $NO_2{^-}$, $NO_3{^-}$, $CO{_3}^{2^-}$, $CH_3COO^-$ and $SO{_4}^{2^-}$ ions. As a final demonstration, some regional water samples from the Sincheon river in Daegu city were analyzed and the data was verified with that of ion chromatography (IC) analysis from one of the Korean-certified water quality evaluation centers.

• 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.

• Journal of Soil and Groundwater Environment
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• v.10 no.4
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• pp.13-17
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• 2005

For the SAT modeling system considering the reaction module which consists of nitrification, denitrification and organic oxidation, an imaginary cross-sectional 2-dimensional model simulation was carried out to analyze the sensitivity of the model. Four parameters, such as hydraulic conductivity, source water loading rate, ground surface pavement and operation schedule, were considered for the sensitivity analysis. Most factors considered in model development step were well reflected in the simulation results.

• Journal of environmental and Sanitary engineering
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• v.10 no.1
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• pp.98-105
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• 1995

In the treatment of wastewater or sewage plant sludge with high solid concentration, high rate digestion process in which heating and mixing occur at a time is mainly used, and in the case of wastewater containing solid matter below 1000mg/ℓ the recently developed AF or UASB is developed Recently and commonly utilized. But these processes have weakpoints such as clogging of packing media and need of long period of trial run after microorganism granulation. In this point of view, there are active researches on the ASBR( anaerobic sequence batch reaction ) that is capable of treating of organic matter with reactor that has no packing materials and controlling the inflow time, reaction time sedimentation time and outflow time by time control without loss of microorganisms. The objectives of this study are to evaluate the efficiency of ASBR process according to the reaction time, change of treated water quality and gas output rate in the treatment of wheat plant wastewater.