• 한국결정성장학회지
• /
• 제9권6호
• /
• pp.590-596
• /
• 1999

염화물욕 아연도금에서 순환셀 도금장치에 3전극계를 부착하여 첨가제 효과를 조사하였다. 도금액에 폴리에틸렌글리콜(이하 PEG)의 첨가는 도금 과전압을 증가시키고 수소발생을 억제하는데 이것은 첨가제에 의하여 아연 이온의 이동을 억제하거나 음극에 첨가제 흡착에 의한 것으로 생각된다. 그러나 PEG는 사용되는 도금액의 물성(전도도, 점도, 비중)에는 영향을 미치지 않는 것으로 나타났다. 도금층에 미치는 영향은 표면 조도가 개선되고, 광택도가 감소된다. 이러한 영향은 PEG 분자수가 클수록 증가되나 분자수가 다른 PEG의 혼합첨가제에서는 광택도 감소가 줄어든다. 이러한 것은 도금층 결정면의 방향성, 입자의 크기 및 형태가 PEG 분자 수에 따라 다르게 나타나는 것에 기인하는 것으로 판단된다.

• 미생물학회지
• /
• 제15권3호
• /
• pp.123-130
• /
• 1977

In previous paper, it was reported that antibiotic substance such as tetracycline and streptomycin were produced by S'. albus subsp. and S'. globosus. And increase of mycelial growth of two strains, antibiotic production, and changes of pH range are extended to approximately 110-130 hrs in fermenting medium, there-after they decreased with culture period exception of pH range. Two Streptomyces spp. required commonly 4-5% starch as carbon sources and 1.5-2.0% soybean meal as nitrogen sources. However, 0.005-0.01M potassium phosphate dibasic, calcium carbonate (6mg/ml in S.albus subsp. and 2mg/ml in S. globosus), 0.01-0.03M, magnesium sulgate and 0.01M ferric chloride showed as optimal concentration for the growth of 2 strains. Mineral compoments such as zinc, manganese, cobalt, sodium and copper at the level of 10/sup -4/ -10/sup -6/M were observed. Especially, zinc ion showed toxicity to the growth of 2 strains at 0.005M. In relation with pH, there is a little difference in mycelial growth with cultural initial pH.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
• /
• pp.215-218
• /
• 2004

The electrokinetically enhanced soil flushing had a great potential to improve the removal efficiency of polycyclic aromatic hydrocarbons (PAHs) from low permeable soils. A semi-pilot study of surfactant-enhanced electrokinetic process was investigated for the removal of phenanthrene from kaolinite. A nonionic surfactant, Tergitol 15-S-12 at 10 g/L was introduced as a flushing agent and 0.001M of sodium chloride was used as an electrolyte. When the constant voltage of 100 V was applied to the system for 25 days, only 0.66 kWh of electric power was consumed and the amount of electroosmotic flow was 6.9 L. The removal efficiency of phenanthrene was about 40 % and it can be improved by increasing the ion concentration of the flushing solution or the applied voltage.

• Journal of Photoscience
• /
• 제4권1호
• /
• pp.17-21
• /
• 1997

The photochemical reactions of the neat chloroform and the aqueous chloroform in the absence (saturated with argon) and presence of 02 (saturated with air or oxygen) have been investigated using 184.9 nm UV light. The irradiation of the deoxygenated neat chloroform causes the formation of hexachloroethane, pentachloroethane, and 1, 1, 2, 2-tetrachloroethane. The initial quantum yields of the products were determined to be 6.37 x 10$^{-4}$, 4.04 x 10$^{-4}$ and 1.76 x 10$^{-4}$, respectively. In the irradiation of aqueous chloroform, chloride ion was also formed along with the products listed above and 1, 1, 2, 2-tetrachloroethane was the predominant product among the chlorinated organic products, which contrasts to the case of the neat chloroform. The presence of oxygen during the irradiation of aqueous chloroform had an effect on the yield of the products. With increasing the concentration of oxygen, the formation of the products was decreased. Probable reaction mechanisms for the photochemical reaction were presented on the basis of products analysis.

• Corrosion Science and Technology
• /
• 제7권1호
• /
• pp.35-39
• /
• 2008

We have been studying application of electrochemical noise (Fluctuation) analysis for localized corrosion. Foils of Zinc, Aluminum and Magnesium were used as specimens for electrochemical cell simulating localized corrosion. These specimens were dipped in sodium chloride solutions adjusted to each exponent of Hydrogen ion concentration (pH) condition of 5.5, 10, 12 respectively. Time variations of potential and current were measured in those solutions, and simultaneously the surfaces of specimens were observed using microscope with television monitor. Two types of electrochemical cells were arranged for experiments simulated localized corrosion. The fluctuations on trendy component of short-circuited potential and short-circuited current were appeared in synchronization. It was seemed that these fluctuations result from hydrogen evolution on the aluminum active site in the crevice from the microscopic observation. In the case of zinc and magnesium, fluctuations appeared on the trendy component of the corrosion potential. Two types fluctuation were detected. First one is the fluctuation varied periodically. The second one is the random fluctuation. It was seemed that these fluctuations result from generation of corrosion products and hydrogen evolution on the active site in the crevice of zinc and magnesium from the microscopic observation.

• 한국물환경학회지
• /
• 제24권1호
• /
• pp.118-122
• /
• 2008

Degradations of phenol and chlorinated compounds mixtures were studied with ultrasound of 20 kHz and 0.57, 1.14 W/mL. In presence of carbon tetrachloride (CT), degradation rate of phenol is faster than chloroform (CF), dichloromethane (DCM) and phenol solution. It is due to that CT generates of free chlorine (HOCl and $OCl^-$) from the sonochemical degradation and plays a role of hydrogen atom scavenger. CF and DCM are react with free chlorine, so amount of free chlorine is smaller than CT solution. The degradation rates of chlorinated compounds decreased with co-presence of phenol in the solution due to the distribution ultrasonic energy to both compounds. The measured chloride ion was lower than the theoretical concentration assuming complete degradation. This means not all the contaminants destructed went through complete degradation.

• 대한토목학회논문집
• /
• 제33권2호
• /
• pp.609-617
• /
• 2013

본 연구에서는 역삼투 공정 농축수에 존재할 수 있는 내분비계 장애물질의 처리에 있어, 고급산화 공정의 적용가능성을 다양한 조건하에서 평가하였다. 오염물 제거에는 Fe(II)를 촉매로 한 과황산나트륨 산화를 이용하였으며, 초기 pH와 이온강도 등, 영향인자에 따른 산화능을 검토하였다. Fe(II) 촉매 과황산나트륨에 의한 $17{\alpha}$-ethynylestradiol(EE2) 제거효율은 초기 pH와 이온강도가 증가할수록 감소하였다. 반면, 이온강도 물질로 염소이온과 같은 할로겐족 이온을 적용 시 산화반응에 긍정적인 영향을 나타냈는데, 이는 라디칼 전이에 따른 영향으로 판단된다.

• Journal of Electrochemical Science and Technology
• /
• 제10권3호
• /
• pp.321-328
• /
• 2019

A new miniaturized all solid-state contact Fe (III)-selective PVC membrane electrode based on Fe (II) phthalocyanine as a neutral carrier was described. The effects of the membrane composition and foreign ions on the electrode performance was investigated. The best performance was obtained with a membrane containing 32% poly (vinyl chloride), 64% dioctylsebacate, 3% Fe (II) phthalocyanine, and 1% potassium tetrakis (p-chlorophenyl) borate. The electrode showed near Nernstian response of $26.04{\pm}0.95mV/decade$ over the wide linear concentration range $1.0{\times}10^{-6}$ to $1.0{\times}10^{-1}M$, and a very low limit of detection $1.8{\pm}0.5{\times}10^{-7}M$. The potentiometric response of the developed electrode was independent at pH 3.5-5.7. The lifetime of the electrode was approximately 3 months and the response time was very short (< 7 s). It exhibited excellent selectivity towards Fe (III) over various cations. The miniaturized all solid-state contact Fe (III)-selective membrane electrode was successfully applied as an indicator electrode for the potentiometric titration of $1.0{\times}10^{-3}M$ Fe (III) ions with a $1.0{\times}10^{-2}M$ EDTA and the direct determination of Fe (III) ions in real water samples.

• 보존과학회지
• /
• 제29권3호
• /
• pp.287-296
• /
• 2013

발굴된 철제유물은 다양한 부식화합물 형태로 발견되며 보존처리 과정을 거쳐 안정한 상태로 보관된다. 하지만 보존처리 후 재부식이 발생하면 철제유물의 심각한 손상이 발생하여 근본적인 대책이 필요하다. 본 연구는 철제유물재부식에 따른 부식화합물의 유형과 특성을 과학적으로 분석하고 표준 철 산화물을 재부식 환경에 노출시켜 부식화합물의 안정성을 평가 하였다. 재부식 실험 결과 철제유물의 균열부위에서 적갈색의 위핑(weeping)이 발생하면서 재부식이 진행되었다. 위핑은 높은 염화 이온과 낮은 수소이온 농도를 가지고 있었으며 최종 부식화합물로서 akagan$\acute{e}$ite가 검출되었다. 위핑에 의한 부식안정성을 평가하기 위하여 goethite, lepidocrocite, hematite, magnetite 표준 철 산화물을 선정하여 HCl(pH 1), $H_2SO_4$(pH 1), $H_2O$(pH 6) 용액에 침적한 후 20%, 50%, 80%의 상대습도에서 180일 동안 유지하며 성분 변화를 알아보았다. 분석 결과 goethite, lepidocrocite, hematite에서는 성분변화가 확인되지 않았지만 magnetite는 염화 이온($Cl^-$)이 함유된 용액에서 lepidocrocite로 황산이온($SO{_4}^{2-}$)이 함유된 용액에서는 goethite, lepidocrocite로 성분이 변화하였다. 실험 결과 비교적 안정한 부식화합물로 알려진 magnetite는 부식성 이온에 의해 부식이 진행되는 것을 확인할 수 있었다. 이는 철제유물에 생성된 위핑이 금속소지 뿐만 아니라 magnetite도 부식 시킬 수 있음을 의미한다.

• 미생물학회지
• /
• 제28권1호
• /
• pp.76-82
• /
• 1990

낙동강에서의 수은 내성세균이 본포를 조사한 결과 $HgCl_{2}$가 20ppm이상 함유된 배지에서 정상이 가능한 수은 내성세균이 전체