• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.777-781
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• 2013

Ion-exchange technology is one of the best for removing nitrate from drinking water. However, problems related to the disposal of spent brine from regeneration of exhausted resins must be overcome so that ion exchange can be applied more widely and economically, especially in small communities. In this background, a combined bio-regeneration and ion-exchange system was operated in order to prove that nitrate-laden resins could be bio-regenerated through direct contact with denitrifying bacteria. A nitrate-selective A520E resin was successfully regenerated by denitrifying bacteria. The bio-regeneration efficiency of nitrate-laden resins increased with the amount of flow passed through the ion-exchange column. When the fully exhausted resin was bio-regenerated for 5 days at the flowrate of 30 BV/hr and MLSS concentration of $125{\pm}25mg/L$, 97.5% of ion-exchange capacity was recovered. Measurement of nitrate concentrations in the column effluents also revealed that less than 5% of nitrate was eluted from the resin during 5 days of bio-regeneration. This result indicates that the main mechanism of bio-regeneration is the direct reduction of nitrate by denitrifying bacteria on the resin.

• Journal of Korean Society for Atmospheric Environment
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• v.1 no.1
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• pp.99-107
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• 1985

A coated wire ion selective electrode for nitrate (nitrate-CWE_ was constructed using epoxy resin, ion exchanger and plasticizer as a polymer membrane. It's stility, the composition of a polymer membrane, the response characteristics, the selectivity were examined and applied to the environmental analysis. The nitrate-CWE was prepared using a copper wire, wihch was coated with epoxy resin being incorporated with the nitrate ion exchanger and plasticizer. The best composition of the polymer membrane for the nitrate-CWE was obtained by mixing epoxy resin, ion exchanger and plasticizer in the ratio of 2:1:0.4. The potential (56.3$\pm$0.5 mV) of stick form nitrate-CWE in this composition was close to that (59.2 mV) of Nernstian response. The detection limit for nitrate ion were found to the about $6 \times 10^{-5}M$ and the useful pH was 2.5 $\sim$ 10.3. Furthermore, the selectivity of iodide and perchrorate for the nitrage-CWE was also much improved compared with that for a liquid membrane nitrate electrode. The nitrate-CWE was used to determind $NO_x$ in stack gas. The results were in good agreement with those obtained either by electrode method or by the improved NEDA method within a relative error of 4.0%.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.383-392
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• 1992

(Bakelite-A)-(2,2'-Bipyridine)-Ni(Ⅱ) Nitrate complexes were tested as ion exchanger for nitrate ion-selective electrode. The experimentally observed selectivity and electrode characteristics were relatively in good agreement with the exchanger lipophilicity in the membrane phase. Based on chemical composition, mechanisms for exchange with nitrate ion and internal electrical conduction were postulated. Analytical application to the determination of nitrate were studied.

• Polymer(Korea)
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• v.27 no.1
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• pp.69-74
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• 2003

In this study, we have investigated the adsorption properties for nitrate ion in ground water using mixed resin type hybrid ion exchange (HIXF) and fiber type ion exchanger. Their swelling ratio (4.45 g/g) and ion exchange capacities (2.45 meq/g) were higer than the swelling ratio of IEC and IXF. Adsorption yield increased for nitrate $NO_3^-$ and sulfate $SO_4^{2-}$ ions were optimal at the concentration ratios of nitrate and sulfate below 1.0 and the adsorption yields were 100% and 20%, respectively. On the other hand it was shown that the degree of adsorpted for nitrate to pH 3, but it was little changed in the other pH range. We found that the selective adsorption capacity for nitrate was the optimal the mixing ratios of resin and fibrous ion exchanger of below 0.5.

• Journal of Biosystems Engineering
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• v.31 no.6 s.119
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• pp.463-473
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• 2006

Automated sensing of soil macronutrients would allow more efficient mapping of soil nutrient spatial variability for variable-rate nutrient management. The capabilities of ion-selective electrodes for sensing macronutrients in soil extracts can be affected by the presence of other ions in the soil itself as well as by high concentrations of ions in soil extractants. Adoption of automated, on-the-go sensing of soil nutrients would be enhanced if a single extracting solution could be used for the concurrent extraction of multiple soil macronutrients. This paper reports on the ability of the Kelowna extractant to extract macronutrients (N, P, and K) from US Corn Belt soils and whether previously developed PVC-based nitrate and potassium ion-selective electrodes could determine the nitrate and potassium concentrations in soil extracts obtained using the Kelowna extractant. The extraction efficiencies of nitrate-N and phosphorus obtained with the Kelowna solution for seven US Corn Belt soils were comparable to those obtained with IM KCI and Mehlich III solutions when measured with automated ion and ICP analyzers, respectively. However, the potassium levels extracted with the Kelowna extractant were, on average, 42% less than those obtained with the Mehlich III solution. Nevertheless, it was expected that Kelowna could extract proportional amounts of potassium ion due to a strong linear relationship ($r^2$ = 0.96). Use of the PVC-based nitrate and potassium ion-selective electrodes proved to be feasible in measuring nitrate-N and potassium ions in Kelowna - soil extracts with almost 1 : 1 relationships and high coefficients of determination ($r^2$ > 0.9) between the levels of nitrate-N and potassium obtained with the ion-selective electrodes and standard analytical instruments.

• Journal of Environmental Science International
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• v.9 no.4
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• pp.319-323
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• 2000

Nitrate-selective ion exchange resin which have bulky tertiary amine as functional group have been synthesized by the reaction of chloromethylated polystyrene-divinylbenzene copolymer and the corresponding tertiary amine [$NR_3=NE_{t3} 1, N{(C_2 H_4 H_3)}_32]$in ethanol, while commercial resin has $NMe_3$ as functional group. The fundamental properties such as bulk density, water content, appearance index, exchange capacity, effective size, uniformity coefficient of synthesized anion exchange resin (1) have been measured. The ion exchange resin (1) and (2) exhibited the better selectivity for nitrate than sulfate in both batch and continuous column experiments.

• Journal of Environmental Science International
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• v.21 no.12
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• pp.1449-1454
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• 2012

The ion selective microelectrodes (ISME) have been applied to observe the continuous profiles of NO3-N and NH4-N in bulk solutions or biofilms. In order to evaluate the performance and applicability of ion concentration measuring system, the characteristics, such as slope of calibration curve, detection limit and potentiometric selectivity coefficient were investigated. The slopes of calibration curve showed high degree of correspondence for each target ion concentrations. And the detection limits of nitrate and ammonia ion selective microelectrode were 10-4.7 M and 10-4.4 M, respectively. These ion selective microelectrodes were proved that their own performance could be maintained for 16 days after making. NO3-N and NH4-N selective microelectrodes were also adapted to detect the continuous ion profiles of cilia media packed MLE (Modified Ludzack-Ettinger) process. And the monitored nitrate and ammonia ion profiles with the ion selective microelectrode were stable and well corresponded to the results with conventional ion chromatograph. However, the electric potential was unstable until 8 hr because of the unknown noise. The tip shape and performance of the ion selective microelectrode was stably kept over 2 days continuous monitoring.

• Preventive Nutrition and Food Science
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• v.1 no.1
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• pp.1-5
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• 1996

Rapid analytical method was investigated to determine precursors of N-nitrosamine such an nitrite and nitrate in squid(Illex illecebrosus and Sepiell maindroni), codfish(Gadus marcrocephalus)and flatfish(Paralichthys olivaceus) by ion chromatography(IC) and colorimetric methods. Recoveries of nitrite and nitrate in fish tissues were 89~98.7% and 94.1~99.8% for IC, and 98.4~103.7% and 67.7~102.2% for colori-metric method, respectively. Using IC, nitrite was not detected and nitrate was 0.89~1.23mg/kg, while using colorimetric method, nitrite and nitrate were NO~0.08mg/kg and 0.3~0.42mg/kg, respectively. Therefore, the IC method showed better recoveries, and was applicable to extract nitrite and nitrate simultaneously, and is simpler compared with colorimetric method in analyzing nitrite and nitrate from fish tissues.

• Journal of Biosystems Engineering
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• v.32 no.1 s.120
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• pp.37-43
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• 2007

This study was carried out to investigate the applicability of PVC membrane-based ion-selective electrodes for macronutrients (K, Ca, and N) by measuring of potassium, calcium, nitrate ions in hydroponic nutrient solution. The capabilities of two ion-selective membranes with varying chemical compositions for each ion were evaluated in terms of sensitivity, selectivity, and lifetime to choose sensing elements suitable for measuring typical ranges of nutrient concentrations in hydroponic solutions. The selected calcium and nitrate ion-selective membranes showed effectively sensitive responses to calcium and nitrate ions with lifetimes of 25 and 15 days, respectively. The addition of a cation additive to the potassium membrane cocktail allowed its sensitivity to be increased whereas its lifetime was reduced from 30 days to 10 days.

• Analytical Science and Technology
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• v.12 no.6
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• pp.583-586
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• 1999

The quantitative analysis of nitrate and nitrite in rain, milk and infant formula was done by Ion Chromatography. The nitrite was not detected(<0.1 mg/L) in all the samples. However, the nitrate was detected in the range of 0.1~4.9 mg/L in rain, 9.8~19.8 mg/L in milk, and 80~300 mg/L in infant formula, respectively. Some content of nitrate is close to the maximum contaminant level(MCL) which is 10 mg/L as $NO_3-N$, 44.3 mg/L as $NO_3$.