• Journal of Life Science
• /
• v.20 no.1
• /
• pp.60-65
• /
• 2010

Since organic sulfur compounds respond to GC/ECD sensitively, they interfere with quantitative separation of pesticides during residual pesticide analysis of Allium species. In this study, it was intended to develop a rapid and simple method for pesticide multi-residues analysis through clean-up and interferences by a solid-phase extraction (SPE). An SPE method employing silver nitrate impregnated Florosil cartridge was developed and evaluated for the elimination of sulfur compounds from the test solution of Allium species during pesticide residues analysis. The silver nitrate impregnated Florosil cartridge was prepared by efflux of 3 ml of 20% silver nitrate solution through Florosil cartridge (1 g packing, 6 ml tube). The extracts equivalent to 2, 4 6, and 10 g of each sample were loaded onto the cartridge and allowed to exude, and then the exudations were analyzed by GC/ECD. More than 95% of sulfur compounds were removed from the loaded extracts equivalent, up to 6 g in onion, 4 g in spring onion and 4 g in shallot, respectively. 40 pesticides were spiked in the Allium species and loaded onto the cartridge to determine the recoveries; from this, the recoveries of 34 pesticides were within 70~120%.

• Korean Journal of Food Science and Technology
• /
• v.53 no.6
• /
• pp.785-791
• /
• 2021

Many lactic acid bacteria (LAB) have probiotic properties that exert various health benefits. In this study, the reduction potential of nitrogen oxide compounds and ferric ions by six LAB, including Lactobacillus kimchicus, L. lactis, L. casei, L. plantarum, L. rhamnosus GG, and Leuconostoc mesenteroides were evaluated. The L. kimchicus strain produced a substantial amount of nitrite reduced from nitrate added to the media, whereas the other five LAB strains did not. L. kimchicus also showed the most potent reducing activity of ferric to ferrous ions. However, the reduction potential of the autoclaved L. kimchicus was little pronounced. The scavenging activities of viable LAB or their cell lysates against different radicals were not consistent with the potency of the LAB's reducing ability. The present results indicate that L. kimchicus has a strong reduction potential for nitrogen oxides in viable status, and that this ability can be used as a probiotic property for various health benefits.

• Journal of environmental and Sanitary engineering
• /
• v.17 no.2
• /
• pp.1-10
• /
• 2002

Ammonia is used in the manufacture of fertilizers, refrigerants, stabilizers and many household cleaning agents. The wide applications result in ammonia contamination in water. Ammonia can be removed from water by physical, biological, and chemical methods. Especially ozonation is effective in the treatment of water with low concentration of ammonia. Therefore, this study is undertaken to provide kinetic data for the ozonation of ammonia with bromide. The results were as follows; Ammonia oxidized by ozone with bromide catalysis. The denitrification rate of the ammonia increased proportionally to the concentration of bromide, and the overall reaction order was zero. It was also found that the effect of bromide ion concentration on the denitrification can be expressed by Monod type equation and there was no more effect above a proper bromide ion concentration. The reacted ammonia was converted completely to nitrate ion without bromide, but the denitrification of ammonia by ozone was conducted in the presence of bromide.

• Korean Journal of Environmental Agriculture
• /
• v.19 no.2
• /
• pp.188-190
• /
• 2000

We explored changes in soil nitrogen (N) availability in a thinned (control, light, moderate, and heavy thinning) Larix leptolepis plantation determined by using ion exchange resin bags. Nitrogen availability varied among measurement periods, however, total available N (ammonium plus nitrate) concentrations did not change significantly in the 1 year since thinning. We found higher N availability in summer and fall than in winter.

• Journal of Korean Society on Water Environment
• /
• v.23 no.3
• /
• pp.319-323
• /
• 2007

The Advanced Oxidation Process (AOP) is being increasingly used to oxidize complex organic constituents in treated effluents from domestic wastewater treatment plants. Generally, ${NO_3}^--N$ concentrations ranges between 5 and 8 mg/L for biologically well-treated effluents. However, nitrate ions, ${NO_3}^-$, affects on oxidation as not only a well-known strong absorber of UV light below 250 nm of wavelength but also as an OH radical scavenger. The objective of this study was to evaluate the AOP systems for degradation of 2,4-DCP, and to delineate the effect of nitrate ions on UV oxidation of 2,4-DCP by conducting a bench-scale operation at various reaction times and initial concentrations of $H_2O_2$. The experimental results indicated that 2,4-DCP could be completely oxidized by $UV/H_2O_2$ process with an initial $H_2O_2$ concentration of 20 mg/L at a retention time of 1.0 min or longer. Nitrate ions did not show any adverse effect on 2,4-DCP oxidation at this high $H_2O_2$ concentration, and the practical initial $H_2O_2$ concentration and reaction time for the 80% oxidation turned out to be 5 mg/L and 1.0 min, respectively.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.24 no.1
• /
• pp.59-63
• /
• 2016

The objective of this study lies in identifying the applicability of zeolite for the removal of wastewater ammonium and nitrate nitrogens. To this end, the author tracked adsorption variations as seen with the adsorption removal of wastewater ammonium and nitrate nitrogens. As a result, it was indicated that the maximum adsorption of zeolite acting on the adsorption removal of ammonium nitrogen would reach 120mg/g (weight of ammonium nitrogen divided by that of zeolite), and that Langmuir adsorption isotherm explained the adsorption of ammonium and nitrate nitrogens better than Freundlich adsorption isotherm. This means that zeolite makes ion exchanges with adsorbate for unilayer adsorption. It was also indicated that the removal efficiency of ammonium nitrogen with varying pH would be higher in the order of pH7 > pH5 > pH9 > pH3.

• Environmental Engineering Research
• /
• v.21 no.2
• /
• pp.188-195
• /
• 2016

$17{\alpha}$-Ethynylestradiol (EE2) has gotten growing concerns due to its widely detected in the environment and high estrogenic potency. However, the knowledge on the photochemical behaviors of EE2 in natural waters is still limited. Herein, the photodegradation and estrogenic potency variation of EE2 induced by nitrate were studied using a sunlight simulator consisted by a 300 W medium pressure mercury lamp and 290 nm cut-off filters. It was found that EE2 could be photodegraded at a rate of $0.0193h^{-1}$ in pure aqueous solutions, and the photodegradation of EE2 could be significantly promoted by nitrate. The photodegradation removal rate of EE2 was increased from 9% in Milli-Q water to 85% in 2.0 mM nitrate solutions. Reactive species scavenging experiments demonstrated that the photogenerated $HO{\bullet}$ contributed about 55% to EE2 degradation. Fe(III), Cl- and dissolved humic acid (DHA) could inhibit the photodegradation of EE2 by competing the incident light and photogenerated $HO{\bullet}$, while $HCO_3{^-}$ had no influence on EE2 photodegradation. EE2 was determined to be phototransformed into organic chemicals without estrogenic potency by GC-MS and MCF-7 cell proliferation toxicity tests. These findings could extend our knowledge on the photochemical behaviors of steroid estrogens and provide information for ecological risk assessment.

• Explosives and Blasting
• /
• v.33 no.2
• /
• pp.1-14
• /
• 2015

This study was performed to investigate the manufacturing process of the Yeomcho(potassium nitrate), a necessary raw material for making gunpowder using soils and ashes by our ancestor. 10 types of soils including underfloor soil and 6 kinds of ashes including mugwort ash were collected, referencing the historical record. The ionic components extracted from the soils and ashes were analyzed by ICP(inductively coupled plasma atomic emission spectrometer) and IC(ion chromatograph). Nitrate ions and potassium ions were dominantly contained in soils and ashes, respectively. In particular, nitrate ions were found in the highest lebels in underfloor soil which often has much exposure to human living environments and accumulated fine organic matter. Potassium ions contained in ash was affected significantly by the type of plant and the growth environments and the measured levels were the highest in mugwort ashes. Yeomcho of 68% purity was obtained from the soil and ash mixture of 1:1 and thid purity was improved by about 14% by fractional crystallization method.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.11
• /
• pp.1965-1971
• /
• 2016

Livestock wastewater containing high concentrations of ammonium and nitrate ions was pretreated with microbubbles and an Fe/MgO catalyst prior to its application in microbial fuel cells because high ion concentrations can interfere with current generation. Therefore, tests were designed to ascertain the effect of pretreatment on current generation. In initial tests, the optimal amount of catalyst was found to be 300 g/l. When 1,000 ml/min $O_2$ was used as the oxidant, the removal of ammonium- and nitrate-nitrogen was highest. After the operating parameters were optimized, the removal of ammonium and nitrate ions was quantified. The maximum ammonium removal was 32.8%, and nitrate was removed by up to 75.8% at a 500 g/l catalyst concentration over the course of the 2 h reaction time. The current was about 0.5 mA when livestock wastewater was used without pretreatment, whereas the current increased to $2.14{\pm}0.08mA$ when livestock wastewater was pretreated with the method described above. This finding demonstrates that a 4-fold increase in the current can be achieved when using pretreated livestock wastewater. The maximum power density and current density performance were $10.3W/m^3$ and $67.5W/m^3$, respectively, during the evaluation of the microbial fuel cells driven by pretreated livestock wastewater.

• Journal of the Korean Applied Science and Technology
• /
• v.33 no.4
• /
• pp.795-801
• /
• 2016

This study is on the denitrification process using the sodium alginate and $CaCl_2$ as a flocculant. Removal techniques of nitrate nitrogen from waste water are reverse osmosis, ion exchange, electro dialysis and biological method etc. We tried to remove nitrate nitrogen with flocculation and sedimentation method in the present study. Calcium alginate is expected to form a chelate bond with nitrate nitrogen in the solution. So the effects of flocculantt component, flocculation reaction time, molar ratio of the flocculant, flocculant injection rate are studied to determine the best removal rate of nitrate nitrogen. In addition, we tried to determine the nitrate nitrogen removal mechanism by analyzing the structure and component ratio of the configuration after the agglutination precipitate by FE-SEM and EDS. As a result, the nitrate nitrogen removal mechanism is turned out to form calcium-nitro-alginate, and the best mole ratio of flocculating agent is 1 : 1, the injection rate of the flocculant was up to 2%, the removal rate of the nitrate nitrogen to be 56.7% in the synthetic wastewater.