• Corrosion Science and Technology
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• 제20권3호
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• pp.129-142
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• 2021

Effects of corrosion inhibitors (i.e., sodium nitrite, sodium hexametaphosphate, trimethylamine (TEA), sugar, and urea) on the corrosion resistance of carbon steel in CaCl₂ solution were investigated. The test solution was designed with response surface methodology of design of experiments (DOE) in the range of 0 ~ 50 ppm for NaNO₂, 0 ~ 200 ppm for (NaPO₃)₆, 0 ~ 2000 ppm for TEA, 0 ~ 3000 ppm for sugar, 0 ~ 200 ppm for urea with 3 wt% CaCl₂. The corrosion potential and the corrosion rate were measured with potentiodynamic polarization tests and analyzed statistically to find main effects of inhibitor concentrations and interactions between them. As a result, hexametaphosphate was the most effective compound in reducing the corrosion rate. Sugar also reduced the corrosion rate significantly possibly because it covered the surface effectively with a high molecular weight. The inhibiting action of sugar was found to be enhanced by adding trimethylamine into the solution. Nevertheless, trimethylamine did not appear to be effective in inhibiting corrosion by itself. However, urea and sodium nitrite showed almost no inhibition on corrosion resistance of steel.

• 한국식품영양과학회지
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• 제28권1호
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• pp.33-39
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• 1999

Traditional kakdugi prepared from salted radish by the addition of fermented shrimp or anchovy sauce along with seasonings and spices, e.g., red pepper powder, garlic or ginger, which has been examined for the formation of volatile nitrosamine(NA) during its fermentation at 5oC and 17oC. Changes of acidity were increased; while, those of ascorbic acid and pH were continually de creased and besides concentrations of salt were scarcely observed during the fermentation of kakdugi at 5oC and 17oC. High initial levels of nitrate in radish followed by a gradual decreased in nitrate concentration, along with increasing levels of nitrite, during its fermentation. During the fermentation of kakdugi, NA such as N nitrosodimethylamine(NDMA) and N nitrosodiethylamine(NDEA) was identified; these NA in kakdugi that had been prepared with shrimp sauce contained in the higher levels than kimchi that had been prepared with anchovy sauce, and both NDMA and NDEA were detected higher levels in the fermented sample at 17oC than in the fermented sample at 5oC. In kakdugi, NDMA and NDEA levels were continually increased during its fermentation; its levels after 35 days fermentation at 17oC were 0.5~16.7 and 0~5.2 g/kg in added shrimp sauce sample, 0. 5~8.7 and 0~4.7 g/kg in added anchovy sauce sample and 0.4~4.8 and 0~2.4 g/kg in control, respectively. The occurrence of NA such as NDMA and NDEA appeared to arise from the fermented sauce and radish used in preparation of the kimchi.

• Preventive Nutrition and Food Science
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• 제6권3호
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• pp.142-146
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• 2001

This study was performed to investigate chemical and functional properties of Glechoma hederacea leaves in respect to its potential use as food material or as a medicinal herb. The chemical compositions on a dry harris were 20.38% in protein, 3.96% in fat, 59.58% in carbohydrate, 15.78% in ash, 5.36% in reducing sugar, 14.11% in total sugar and 0.26% in polyphenol, respectively. The free sugars were mainly comprised of glucose, fructose and sucrose. In fatty acids compositiosn, linolenic acid showed the highest concentration at 45%, while the ratios of saturated to unsaturated fatty acids were 1 : 1.91. Seventeen kinds of total amino acids were determined, with the highest concentration (2,465.71 mg%) of glutamic acid. Among the free amino acids, praline showed the highest concentration (260.09 mg%), followed by glutamine, $\alpha$ -amino adipic acid, glutamic acid and valine. The contents of major minerals were 647.32 mg% in Na, 597.53 mg% in K and 239.75 mg% in Ca. The antioxidative activity of 10% water extract was similar to that of 50 ppm tocopherol. The nitrite scavenging ability reached the highest bevel at pH 1.2 and the lowest at pH 6.0.

• Corrosion Science and Technology
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• 제16권3호
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• pp.91-99
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• 2017

The objective of this work was to develop efficient synergistic inhibitor combinations comprising sodium nitrite ($NaNO_2$) and an inhibitor-blend code named (SN-50), keeping in view of their application in industrial cooling water systems. The electrochemical characteristics of the carbon steel working electrode in simulated cooling water (SCW), without and with the addition of different combinations of the inhibitors, were investigated using electrochemical impedance spectroscopy (EIS), open circuit potential (OCP). The electrode surface changes were followed by visual characterization methods. It was demonstrated in this study that all the combinations of the inhibitors exhibited synergistic benefit and higher inhibition efficiencies than did either of the individual inhibitors. The addition of SN-50 inhibitor to the SCW shifted the OCP to more anodic values and increased the polarization resistance ($R_p$) values of carbon steel at all applied concentrations. The higher the applied sodium nitrite concentration (in the protection concentration range), the higher the obtained $R_p$ values and the inhibition efficiency improved by increasing the inhibitor concentration.

• 한국물환경학회지
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• 제18권2호
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• pp.113-122
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• 2002

A bench-scale anoxic membrane bioreactor (MBR) system, consisting of a bioreactor coupled to a ceramic crossflow ultrafiltration module, was evaluated to treat a synthetic wastewater containing alkaline hydrolysis byproducts (hydrolysates) of RDX, The wastewater was formulated the same as RDX hydrolysates, and consisted of acetate, formate, formaldehyde as carbon sources and nitrite, nitrate as electron accepters. The MBR system removed 80 to 90% of these carbon sources, and approximately 90% of the stoichiometric amount of nitrate, 60% of nitrite. The reactor was also operated over a range of transmembrane pressures, temperatures, suspended solids concentration, and organic loading rate in order to maximize treatment efficiency and permeate flux. Increasing transmembrane pressure and temperature did not improve membrane flux significantly. Increasing biomass concentration in the bioreactor decreased the permeate flux significantly. The maximum volumetric organic loading rate was $0.72kg\;COD/m^3/day$, and the maximum F/M ratio was 0.50 kg N/kg MLSS/day and 1.82 kg COD/kg MLSS/day. Membrane permeate was clear and essentially free of bacteria, as indicated by heterotrophic plate count. Permeate flux ranged between 0.15 and $2.0m^3/m^2/day$ and was maintained by routine backwashing every 3 to 4 day. Backwashing with 2% NaOCl solution every fourth or fifth backwashing cycle was able to restore membrane flux to its original value.

• 한국식품영양과학회지
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• 제17권2호
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• pp.125-135
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• 1988

예부터 우리나라 특유의 조미료로 상용되어온 재래식 간장을 제조함에 있어 강한 발암성 물질인 N-nitrosamine(NA)의 생성유래를 밝히고, 나아가서 이들의 생성을 억제시키는 방안의 일환으로써 몇몇 종의 식품첨가제를 이용하여 NA 생성에 미치는 영향을 검토하였고, 동시에 NA 생성과 밀접한 관계가 있는 유리아미노산, dimethylamine(DMA), 질산염 및 아질산염의 변화를 검색하였다. 간장숙성중 DMA 질소는 다소간 불규칙한 변화를 보이고 있으나 대체로 숙성과 더불어 증가하는 경향이었다. DMA의 억제효과는 ascorbic acid 및 sodium benzoate 처리구가 DMA생성을 숙성초기에 크게 억제시켰으나 숙성말기에는 큰영향을 미치지 못하였다. 질산염질소는 간장이 숙성되는 과정중 계속해서 감소하는 추세였으나, 반면 아질산염질소는 증가하였다. 아질산염의 생성을 최소화하기 위해서는 ascorbic acid가 가장 효과적인 식품첨가제였다. N-nitrosodimethylamine (NDMA)은 간장숙성중 증가하는 경향을 보여 대조구의 경우 숙성 30일에 $2.7{\mu}g/kg$, 숙성 90일에 $10.7{\mu}g/kg$검출되었다. 그러나 N-nitrosodiethylamine(NDEA) 및 N-nitrosodipropylamine(NDPA) 은 전혀 검출되지 않았다. 식품첨가제가 NDMA의 생성에 대한 억제효과는 시판식염으로 제조한 간장에서는 대조구에 비해 ascorbic acid 처리구가 $82.2{\sim}87.0%$, sorbic acid 처리구 $25.9{\sim}65.4%$ 및 sodium benzoate 처리구에서는 $13.2{\sim}63.5%$의 억제효과를 보였다. 그리고 순 NaCI로 제조한 간장중 NDMA의 함량은 ascorbic acid 처리구가 1.5㎍/㎏이하로서 대조구에 비해 NDMA의 생성이 크게 억제되었다. 간장중에 존재하는 유리아미노산이 NDMA의 생성을 억제시킨다는 것이 본 실험에서 밝혀졌고, 이중 특히 glutamic acid, proline 및 histidine이 주된 아미노산으로 추정되며 모델실험결과 간장중 유리아미노산을 제거할 경우 NDMA의 생성을 30.3%나 촉진시켰다.

• 한국식품영양과학회지
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• 제31권3호
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• pp.378-383
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• 2002

우리나라 고유의 조미료인 간장 및 된장, 대중적인 알코올 음료인 맥주를 대상으로 하여 발암성 N-nitrosamine(NA)을 분석하였고, 또 인공타액 및 위액을 혼합하여 in vitro에서 인공소화시킴으로써 섭취 후 생체내에서 생성 가능한 NA를 예측하고자 하였다. 대상시료 중 질산염은 간장에서 0.3~0.9 mg/kg, 된장에서 0.5~1.0 mg/kg, 맥주에서 0.5~1.3 mg/kg, 아질산염 은 모든 시료에서 평 균 0.3 mg/kg이었으며, DMA 및 TMA는 0.5 mg/kg 이하로 정량되 었다. NA를 분석한 결과, 모든 시료에서 NDMA만이 검출되었으며, 간장에서 <0.5~2.7ug/kg, 된장에서는 1.5~3.1ug/kg, 맥주에서는 <0.5~1.8ug/kg으로 정량되었고, 인공소화 후에는 각각 1.1배, 4.5배 및 1.6배 증가되었다. 아질산염을 농도별로 첨가하여 인공소화시킬 때 모든 시료에서 대조구에 비하여 아질산염의 농도가 높아질수록 NDMA가 증가되었고, 인공소화시 6.4 mM의 thiocyanate를 맥주에 첨가할 때 대조구에 비해 NDMA가 무려 3.3배로 가장 많이 증가하였다. Ascorbic acid를 첨가하여 인공소화시킨 결과전 시료에서 NDMA의 생성이 억제되었으며 특히 12.8 mM의 ascorbic acid를 첨가한 된장에서 NDMA 생성은 약 92.3%나 억제되었다.

• 한국수산과학회지
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• 제20권5호
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• pp.463-468
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• 1987

일상 식생활에서 널리 섭취하고 있는 야채류를 사용하여 니트로사민의 직접적인 생성인자인 아질산염 분해작용에 관하여 검토하였는데, 그 결과를 요약하면 다음과 같다. 1. 마늘, 산초, 생강, 양파 및 파 둥은 수용성획분에서 당근은 methanol 가용성획분에서 각각 아질산염 분핵능이 높게 나타났다. 2. 반응용액의 pH변화에 따른 아질산염 분해능은 pH 1.2에서 가장 컸으며, pH가 증가할수록 분해능은 감소하였다. 3. 각 시료를 10mg씩 취하여 얻은 아질산염 분해능을 동량의 L-ascorbic acid와 비교한 경우, 마늘과 산초가 수용성획분에서 L-ascorbic acid와 거의 비슷한 분해능을 나타내었다. 4. 각 시료를 $NaBH_4$로 처리하여 환원능을 소실시킨 후에 측정한 아질산염 분해능은 pH 1.2에서 시료 모두 모두 그 값이 현저하게 감소하였다

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.590-593
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• 2001

The effect of salinity on the nitrification efficiency of the nitrifier consortium was evaluated for the nitrification of saline wastewater. The nitrifier consortium, which was the activated sludge acclimated with ammonium as the only energy source, was used as the nitrifier for the salt acclimation. Airlift reactors for the nitrification of ammonia with increasing concentration in saline synthetic wastewater (35 g/I NaCD, and synthetic wastewater without salt as a control, were continuously operated with the nitrifier consortium for 43 days. The ammonia removal rate was about 23g ammonia-N/$m^3$/day in both the absence and presence of the salt. An accumulation of nitrite was observed in the saline nitrification reactor at an early period. However, the nitrite decreased to less than 1 mg/l after 39 days of operation. The salinity increased the acclimation time of the nitrifier consortium to obtain a stable marine nitrification system. However, the salt acclimated system showed the efficient removal of ammonia which was same as that without salt.

• Journal of Nutrition and Health
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• 제7권4호
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• pp.21-23
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• 1974

Nitrite, one of the precursors of dimethylnitrosamine distributes widely in natural foods and also used as a color fixative in meat products. In this paper Nitrites and Nitrates contents in Korean-Kimchi and Human Saliva were as follows. (1) pH: $pH:\;3.8{\sim}5.8$(in Korean-Kimchi soup) (2) NaCl: $1.5{\sim}3.1%$(in Korean-Kimchi soup) (3) Acidity: $0.38{\sim}0.62%$(in Korean-Kimchi soup) (4) $NO_2-$ $0.25{\sim}0.68ppm$ (in Korean-Kimchi) $1.9{\sim}5.0ppm$ (in Human Saliva) (5) $NO_3-$ $35.0{\sim}92.0ppm$ (in Korean-Kimchi) $7.6{\sim}28.0ppm$ (in Human Saliva) These results showed low contents in Korean-Kimchi and Human Saliva.