• Journal of Environmental Science International
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• v.21 no.5
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• pp.597-603
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• 2012

Non-thermal plasma processing using a dielectric barrier discharge (DBD) has been investigated as an alternative method for the degradation of non-biodegradable organic compounds in wastewater. The active species such as OH radical, produced by the electrical discharge may play an important role in degrading organic compound in water. The degradation of N, N-Dimethyl-4-nitrosoaniline (RNO) was investigated as an indicator of the generation of OH radical. The DBD plasma reactor of this study consisted of a plasma reactor, recycling pump, power supply and reservoir. The effect of diameter of external reactor (15 ~ 40 mm), width of ground electrode (2.5 ~ 30 cm), shape (pipe, spring) and material (copper, stainless steel and titanium) of ground electrode, water circulation rate (3.1 ~ 54.8 cm/s), air flow rate (0.5 ~ 3.0 L/min) and ratio of packing material (0 ~ 100 %) were evaluated. The experimental results showed that shape and materials of ground were not influenced the RNO degradation. Optimum diameter of external reactor, water circulation rate and air flow rate for RNO degradation were 30 mm, 25.4 cm/s and 4 L/min, respectively. Ground electrode length to get the maximum RNO degradation was 30 cm, which was same as reactor length. Filling up of glass beads decreased the RNO degradation. Among the experimented parameters, air flow rate was most important parameters which are influenced the decomposition of RNO.

• Journal of the Korean Wood Science and Technology
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• v.38 no.6
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• pp.568-578
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• 2010

In this study, the possibility of biodegradation of polychlorinated biphenyls (PCBs) by various white rot fungi was evaluated, and outstanding white rot fungi for the degradation of PCBs were selected. Seven white rot fungi were used to degrade Aroclor 1254 and 1260, which are widely considered to be toxic and difficult to degrade. And the degradation rates of Aroclors by selected white rot fungi were performed by GC analysis. Through the resistance test of white rot fungi on different concentrations of PCBs, the inhibition of mycelial growth of Cystidodontia isubellina was much less than that of others, and this fungus grew faster than others, relatively. Based on this result, it was considered that C. isubellina was selected as degrading fungus for Aroclors. As a result of biodegradation rate of Aroclors by Cystidodontia isubellina, the degradation rate of Arolor 1254 was reached to 57.57% in 13 days, which showed very high degradation rate. Also the degradation rate of Aroclor 1260 by C. isubellina had a tendency of increasing along with increasing incubation day. Maximal degradation rate of Aroclor 1260 was 49.43% at 13 days. Based on this results, it indicated that in comparison with a previous study, high degradation rate was obtained by C. isubellina.

• The International Journal of Costume Culture
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• v.7 no.1
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• pp.40-47
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• 2004

The purpose of this research was to examine the degradation rate of alizarin in accelerated degradation conditions using the GC-MS quantitative analysis. Alizarin dye solution (2.5 x 10/sup -3/ M conc.) were kept in 150℃ oven for total of 7 days and the degradation rate was examined each day. 2.5 × 10/sup -4/M conc. alizarin dye solution was mixed with H₂O₂ according to [H₂O₂]/[dye] ratio 40 and were kept under 365㎚ UV for 2 hours, analyzed after 0, 30, 60, 90, 120min using the GC-MS. Gas chromatogram showed alizarin peak at 9.96 - 10.13 min. retention time range and residual peaks in the wide range from 9.6 to 11.1 min. Oven degradation exhibited an initial decrease in the amount of alizarin, which was followed by increasing amount in 4/sup th/ day. The decrease in the alizarin was significantly shown by the 7/sup th/ day. Same pattern was also observed in the H₂O₂/UV/O₂ degradation samples and was verified ed by the UV-VIS spectra. The differences in the amount of alizarin between 1/sup st/ day and 4/sup th/ day samples, 4/sup th/ day and 7/sup th/ day samples, and Control and 7/sup th/ day samples of the oven degradation were significant at alpha .20.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.1
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• pp.44-51
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• 1998

In order to develop the evaluation methods of degradation for the Ni-Cr-Mo-V steel, which is in use for turbine rotor in nuclear power plant, the degraded materials were prepared by simulated degradation methods. The result of impact test and fatigue crack growth test shows that the FATT(Fracture Appearance Transition Temperature) and fatigue crack growth rate increased with the increase of degradation. And the result of new electrochemical polarization test method was suggested for the evaluating FATT, fatigue crack growth exponent and coefficient C values based on the results of relationship between corrosion current density(Icorr) & FATT, and the m & C and Icorr.

• Journal of Environmental Science International
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• v.11 no.6
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• pp.561-567
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• 2002

This study was investigated to evaluate the effect of the sodium ion and pH on toxicity of dinitrophenol at high concentrations (0.41 to 0.54 mM), over a sodium concentration range of 0.1 mM to 107 mM and over a pH range of 5 to 9. The concentration of sodium ions in the activated sludge mixed liquor seemed to have very little effect on dinitrophenol toxicity. However, lack of sodium in the growth media resulted in a reduction of the dinitrophenol degradation rate by bacterial isolate from the activated sludge culture, which has been identified as Nocardia asteroides. Dinitrophenol inhibition was found to be strongly dependent on mixed liquor pH. The dinitrophenol degradation rate was highest in the pH range of 6.95 to 7.84; at pH 5.94 degradation of 75 mg/L dinitrophenol was significantly inhibited; at pH < 5.77, dinitrophenol degradation was completely inhibited after approximately 30% of the dinitrophenol was degraded.

• Journal of Applied Reliability
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• v.2 no.2
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• pp.63-83
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• 2002

Degradation data can provide more reliability information than traditional failure-time data, especially products with few or no failures. This paper is concerned with a method of estimating lifetime distribution from field data with supplementary information on degradation data and covariates. When a distribution of degradation rate obtained by follow-up study for a portion of products that survive after-warranty follows a reciprocal-Weibull or lognormal distribution. A time-to-failure distribution of the product follows Weibull or lognormal distribution, respectively. A method of estimating lifetime parameters for this kind of data and their asymptotic properties are studied. Effects of after-warranty report probability, follow-up rate, and proportion of degradation data on pseudo maximum likelihood estimators of these parameters are investigated.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.680-685
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• 1998

Two kinds of new aliphatic diols were synthesized by the ring-opening reaction of lactide and glycolide with 1,4-butanediol, a difunctional initiator, in the presence of stannous octoate. The resulting aliphatic diols were melt-polymerized with D-tartaric acid at 150 ℃ to produce new crosslinkable polyesters. They were reacted with hexamethylene diisocyanate in THF at 65 ℃ in a teflon mold for 24 h to prepare sequentially ordered crosslinked polyesters (BD/LT/GL/D-tartarate). Degradation of the prepared yellow crosslinked films was carried out in a buffer solution in order to examine the effect of time, pH, temperature and crosslinking degree on their degradation rate and mechanism. The rate of degradation increased with an increase in pH and temperature, but it decreased with increasing degree of crosslinkage incorporated into the crosslinked polyesters. We also found that the crosslinked polymers were converted into the acidic compounds such as lactic, glycolic, and D-tartaric acids during the degradation.

• Environmental Engineering Research
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• v.16 no.3
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• pp.131-136
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• 2011

The degradation of 30 pharmaceuticals and personal care products (PPCPs) subjected to $O_3$, $O_3$/UV, and $O_3/H_2O_2$ treatments were investigated using semi-batch tests and evaluated by their pseudo-first-order rate constants. The additional application of UV or $H_2O_2$ during $O_3$ treatment significantly improved the degradation rate of most of the PPCPs. At the same $O_3$ feed rate, $O_3$/UV treatment exhibited much higher PPCP degradation efficiency than that of $O_3$ treatment. This was probably due to degradation of the PPCPs by $O_3$, direct UV photodegradation, and OH radicals that formed from the photodegradation of $O_3$ during $O_3$/UV treatment. PPCP degradation by $O_3$ was also promoted by adding $H_2O_2$ during the $O_3$ treatment. However, when the initial $H_2O_2$ concentration was high during $O_3$ treatment, OH radicals were likely to be scavenged by excess $H_2O_2$, leading to low PPCP degradation. Therefore, it is important to determine the appropriate $H_2O_2$ dosage during $O_3$ treatment to improve PPCP degradation when adding $H_2O_2$ during $O_3$ treatment.

• Journal of Environmental Science International
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• v.21 no.7
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• pp.845-853
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• 2012

Diethyl phthalate (DEP) is widely spread in the natural environment as an endocrine disruption chemicals (EDs). Therefore, in this study, ultrasound (US) and ultraviolet (UVC), including various applied power density (10-40 W/L), UV wavelengths (365 nm, 254 nm and 185 nm) and frequencies (283 kHz, 935 kHz) were applied to a DEP contaminated solution. The pseudo-first order degradation rate constants were in the order of $10^{-1}$ to $10^{-4}\;min^{-1}$ depending on the processes. Photolytic and sonophotolytic DEP degradation rate also were high at shortest UV wavelength (VUV) due to the higher energy of photons, higher molar absorption coefficient of DEP and increased hydroxyl radical generation from homolysis of water. Sonolytic DEP degradation rate increased with increase of applied input power and the dominant reaction mechanism of DEP in sonolysis was estimated as hydroxyl radical reaction by the addition of t-BuOH, which is a common hydroxyl radical scavenger. Moreover, synergistic effect of were also observed for sonophotolytic degradation with various UV irradiation.

• Journal of environmental and Sanitary engineering
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• v.8 no.1
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• pp.81-91
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• 1993

This paper was carried out to isolate and identify Aeromonas caviae which can degrade Sodium Dodecyl Benzene Sulfonate(SDBS) effectively. And the affecting factors for the ability of bacterial degradation were also studied. Frm October 1991 to February 1992, two hundred samples from sweage in Taegu area and Nakdong river waters in Talsung Gun area were tested. Minimal salt medium which contain SDBS only as a carbon source was used as a culture medium. The isolated new strain was identified as Aeromonas caviae Kim & Kweon. The optimal pH for SDBS degradation were 7.0 and temperature, $32^{\circ}C.$ It was taken 24 hours to degrade SDBS of 20mg/l completely under the optimal pH and temperature. And in the case of 30 mg/l of SDBS, it was taken 36 hours. The nitrogen sources were added to the minimal salt media containing 20mg/l of SDBS, and they were incubated at $32^{\circ}C$ for 14 hours. 86.9% SDBS were degraded after addition of 0.03% peptone as a organic nitrogen source. And 70.5% SDBS after addition of 0.05% ammonium sulfate as a inorganic nitrogen source. In the case of metal compounds(0.015%), the degradation rate for SDBS were 3.5 fold increased in the media containing magnesium chloride and calcium chloride than in the media that were not containing these metal compounds. And where the media containing magnesium chloride was 0.05%, the degradation rate was 65.8%. And above 0.3% NaCI, the degradation rate was decreased slowly.