• Advances in materials Research
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• 제3권1호
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• pp.259-269
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• 2014

The boron-nitrogen-containing phenol-formaldehyde resin (BNPFR)/$SiO_2$ nanocomposites (BNPFR/$SiO_2$) were synthesized in-situ, and structure of BNPFR/$SiO_2$ nanocomposites was characterized by FTIR, XRD and TEM. The loss modulus peak temperature $T_p$ of BNPFR/$SiO_2$ nanocomposites cured with different nano-$SiO_2$ content are determined by torsional braid analysis (TBA). The thermal degradation kinetics was investigated by thermogravimetric analysis (TGA). The results show that nano-$SiO_2$ particulate with about 50 nm diameter has a more uniformly distribution in the samples. The loss modulus peak temperature $T_p$ of BNPFR/$SiO_2$ nanocomposite is $214^{\circ}C$ when nano-$SiO_2$ content is 6 wt%. The start thermal degradation temperature $T_{di}$ is higher about $30^{\circ}C$ than pure BNPFR. The residual rate (%) of nanocomposites at $800^{\circ}C$ is above 40 % when nano-$SiO_2$ content is 9 %. The thermal degradation process is multistage decomposition and following first order.

• 한국지하수토양환경학회지:지하수토양환경
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• 제6권2호
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• pp.39-47
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• 2001

회분식 세척실험에서 적용된 혼합계면활성제 중 $POE_5$ + $POE_14$, SDS+$POE_5$가 endosulfan의 탈착에 효율이 우수한 것으로 나타났으며, 독성실험 결과 SDS+POE$_{5}$는 미생물의 활성을 다소 저해시키는 경향이 있어 $POE_5$ + $POE_14$ (1:1) 1%를 세척제로 선정하였다. In-Situ flushing 실험에서는 세척용액의 주입 flux가 1.5L/min/m$^2$일 때 67%의 제거효율을 얻을 수 있었으며, 보조용매로서 메탄올과 에탄올을 첨가한 경우에는 각각 75%와 81%의 제거효율을 보였다. In-situ flushing기법의 적용에 따른 농도 저감이 생물학적 분해에 미치는 영향을 알아보기 위하여, 초기 농도 13mg/kg dry soil과 3mg/kg dry soil인 토양을 생물학적으로 처리한 결과 제거 효율은 각각 86% 및 81%였으며, 2가지 토양 모두 24시간 이후에는 미생물에 의한 작용이 크지 않은 것으로 나타났다. 이것은 토양상에서 용액상으로의 물질전이 속도가 율속 단계로 작용하고 있기 때문이라 판단된다. 토양에 잔류하는 계면활성제가 생물학적 분해에 미치는 영향에 대하여 검토한 결과, 잔류하는 계면활성제에 의해 물질전이 속도가 향상되어 생분해가 지속적으로 일어났으며 초기 농도 3mg/kg dry soil인 경우 120시간이 경과한 후 89%의 제거효율을 나타내었다. 계면활성제와 보조용매가 동시에 잔류하는 경우에는 계면활성제에 대한 순응기간이 보다 길어지는 것을 알 수 있었으며, 메탄올과 에탄올의 경우 각각 84% 및 83%의 제거효율을 나타내었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.689-690
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• 2012

• 한국지하수토양환경학회지:지하수토양환경
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• 제25권2_spc호
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• pp.1-15
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• 2020

Monitoring and assessing terminal electron accepting processes (TEAPs) are one of the most important steps to remediate contaminated sites via various in-situ techniques. TEAPs are a part of the microbial respiration reactions. Microorganisms gain energy from these reactions and reduces pollutants. Monitoring TEAPs enables us to predict degradability of contaminants and degradation rates. In many countries, TEAPs have been used for characterization of field sites and management of groundwater wells. For instance, US Environmental Protection Agency (EPA) provided strategies for groundwater quality and well management by applying TEAPs monitoring. Denmark has also constructed TEAPs map of local unit area to develop effective groundwater managing system, particularly to predict and assess nitrogen contamination. In case of Korea, although detailed soil survey and groundwater contamination assessment have been employed, site investigation guidelines using TEAPs have not been established yet. To better define TEAPs in subsurface environments, multiple indicators including ion concentrations, isotope compositions and contaminant degradation byproducts must be assessed. Furthermore, dissolved hydrogen concentrations are regarded as significant evidence of TEAPs occurring in subsurface environment. This review study introduces optimal sampling techniques of groundwater and dissolved hydrogen, and further discuss how to assess TEAPs in contaminated subsurface environments according to several contamination scenarios.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권6호
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• pp.117-126
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• 2015

Reductive degradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by nanoscale zero-valent iron (nZVI) was investigated to evaluate the feasibility of using it for in-situ groundwater remediation. Batch experiments were conducted to quantify the kinetics and efficiency of RDX removal by nZVI, and to determine the effects of pH, dissolved oxygen (DO), and ionic strength on this process. Experimental results showed that the reduction of RDX by nZVI followed pseudo-first order kinetics with the observed rate constant (k_obs) in the range of 0.0056-0.0192 min⁻¹. Column tests were conducted to quantify the removal of RDX by nZVI under real groundwater conditions and evaluate the potential efficacy of nZVI for this purpose in real conditions. In column experiment, RDX removal capacity of nZVI was determined to be 82,500 mg/kg nZVI. pH, oxidation-reduction potential (ORP), and DO concentration varied significantly during the column experiments; the occurrence of these changes suggests that monitoring these quantities may be useful in evaluation of the reactivity of nZVI, because the most critical mechanisms for RDX removal are based on the chemical reduction reactions. These results revealed that nZVI can significantly degrade RDX and that use of nZVI could be an effective method for in-situ remediation of RDX-contaminated groundwater.

• 상하수도학회지
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• 제32권6호
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• pp.499-505
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• 2018

We applied column experiments to investigate the environmental fate and transport of silver nanoparticles(AgNPs) in fully saturated conditions of porous media. These column experiments were performed to emphasize oxidation method with $H_2O_2$ concentration and acidic conditions. The mobility of AgNPs was decreased with the increasing ionic strength that the surface charge of AgNPs(zeta potential) was neutralized with the presence of positive ions of $Na^+$. Additionally, it was also affected due to that not only more increased aggregated size of AgNPs and surface charge of quartz sand. The decreased breakthrough curves(BTCs) of bisphenol-A(BPA) and $17{\alpha}$-ethynylestradiol(EE2) were removed approximately 35.3 and 40%. This is due to that endocrine disrupting chemicals(EDCs) were removed with the release of $OH{\cdot}$ radicals by the fenton-like mechanisms from acidic and fenton-like reagent presenting. This results considered that higher input AgNPs with acidic conditions is proved to realistic in-situ oxidation method. Overall, it should be emphasized that a set of column experiments employed with adjusting pH and $H_2O_2$ concentration in proved to be effective method having potential ability of in-situ degradation for removing organic contaminants such as BPA and EE2.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
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• pp.54-56
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• 2006

Single-well-gas-sparging tests were developed and evaluated for assessing the feasibility of in-situ aerobic cometabolism of trichloroethylene (TCE), using propane as a growth substrate. To evaluate transport characteristics of dissolved solutes [sulfur hexafluoride (SF6) or bromide (non-reactive tracers), propane (a growth substrate), ethylene, propylene (nontoxic surrogates to probe for CAH transformation activity), and DO], push-pull transport tests were performed. Mass balance showed about 90% of the injected bromide and about 80% of the injected SF6 were recovered, and the recoveries of other solutes were comparable with bromide and slightly higher than SF6. A series of Gas-Sparging Biostimulation tests were performed by sparging propane/oxygen/argon/SF6 gas mixtures, and temporal ground water samples were obtained from the injection well under natural gradient 'drift' conditions. The decreased time for propane depletion and the longer time to deplete SF6 as a conservative tracer indicate the progress of biostimulation. Gas-Sparging Activity tests were performed. .Propane utilization, DO consumption, and ethylene and propylene cometabolism were well demonstrated. The stimulated propane-utilizers cometabolized ethylene and propylene to produce ethylene oxide and propylene oxide, as cometabolic by-products, respectively. Gas-Sparging Acetylene Blocking tests were performed by sparging gas mixtures including acetylene to demonstrate the involvement of monooxygenase enzymes. Gas substrate degradation was essentially completely Inhibited in the presence of acetylene, and no production of the corresponding oxides was also observed. The Gas-Sparging tests supports the evidences that the successive stimulation of propane-oxidizing microorganisms, cometabolic transformation of ethylene and propylene by the enzyme responsible for methane and propane degradation.

• Journal of Animal Science and Technology
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• 제48권5호
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• pp.699-708
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• 2006

본 시험은 반추위 누관이 시술된 한우 수소 3두를 이용하여 쌀, 옥수수 및 보리의 in situ 분해율과 in vitro 시험으로서 영양소 분해율, 미생물 성장량, pH 변화 및 gas 발생량을 비교분석함으로써 쌀의 사료적 이용성을 평가해 보고자 수행되었다.In situ 건물 및 유기물 소실율은 반추위내 24시간 발효 시, 보리와 쌀은 거의 대부분이 소실된 반면, 옥수수는 약 67%만 소실되어 분해 속도가 매우 느린 것으로 나타났다. 수용성 물질인 ‘a’ 부분은 옥수수, 쌀, 보리 순으로 많았으며, 천천히 분해되는 ‘b’ 부분은 ‘a’ 부분과 정 반대의 경향으로서 ‘b’ 부분의 분해 상수(‘c’ 부분)로부터 시간당 건물과 유기물의 분해속도는 보리의 경우 각각 38.3%, 37.2%로서 쌀(7.7%, 5.6%)이나 옥수수(4.1%, 1.3%)에 비해 매우 빠르게 일어났다. In vitro 건물 및 유기물 분해율은 in situ 분해율에 비해 수준은 현저히 낮았으나, 보리, 쌀, 옥수수 순으로 높아 곡류 간 순서는 일치하였다. In vitro 미생물 성장은 쌀이 옥수수나 보리보다 상대적으로 낮았으나, 가스 발생량은 높게 나타났으며, pH는 발효시간에 따른 저하속도가 쌀에서 가장 느린 것으로 나타났다. 발효시간에 따른 미생물 성장량은 발효 12시간까지 높아졌다가 이후로 감소하였고, 배양액의 pH는 발효초기에는 높았다가 이후로 점차 감소하였으며, gas 발생량은 발효 9시간까지는 빠르게 증가하였다가 이후로 증가폭이 둔화되었다.이상의 결과에서 반추위내 건물과 유기물의 분해율과 발효시간의 경과에 따른 pH의 저하속도 등을 고려하면, 쌀은 옥수수와 함께 반추위내 발효 안정을 위한 에너지원으로서 사용 할 수 있을 것으로 사료된다.

• 공업화학
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• 제29권1호
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• pp.117-121
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• 2018

하폐수 고도산화처리(AOP, advanced oxidation process) 중 하나인 펜톤산화법과 전기화학적 방법을 결합한 전기펜톤산화법의 cathode에 stainless steel mesh (SUS mesh)를 적용하였다. 난분해성 물질인 염료 methylene blue (MB) 용액에 대해서, SUS mesh의 표면 처리 및 산화철 코팅 여부에 따라 전기펜톤산화 처리의 효율이 어떻게 달라지는지를 비교, 분석하였다. MB분해 반응의 효율 비교를 통해 mesh 표면에 코팅된 산화철의 양이 많을수록 전극의 촉매 특성이 높아짐을 확인하였고, 이는 전극표면에서 in situ로 발생하는 과산화수소의 발생량이 높아지는 것과 연관이 있었다. 전류-전위 순환법(CV)을 통해 개발된 전극의 전기화학적 특성을 평가해 본 결과, mesh 표면에 코팅된 산화철의 양이 많을수록 전기화학적 산화-환원 특성 또한 개선되었고, 이것이 우수한 전기펜톤산화 전극으로서의 성능과 밀접한 관계가 있음을 확인하였다.

• Journal of Animal Science and Technology
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• 제59권10호
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• pp.22.1-22.7
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• 2017

Background: Very limited information exists on the ruminal degradation kinetics of nutrients in garlic stalk. The present study aimed to survey the annual yield of garlic stalk in Korea and determine its feed-nutritive value for ruminants. Methods: In Experiment 1, garlic stalk was incubated in situ in the rumen of two Hanwoo steers ($360{\pm}15kg$ body weight) and removed after 12, 24, or 48 h to determine the ruminal degradation kinetics of DM and NDF. Rice straw was also included for comparison. In Experiment 2, In Experiment 2, six male Corriedale sheep were randomized to two dietary treatments to determine the apparent digestibility of nutrients in garlic stalk. Diets included a control ration without garlic stalk (60% concentrate mix +40% ryegrass) or a treatment ration (70% control diet +30% garlic stalk). Results: The Korean national yield of garlic stalk (sun-dried basis) in 2016 was estimated to be 31,910 tons, with the southern coastal regions producing the highest quantity. Compared with rice straw, garlic stalk had lower NDF, higher ADF, and greater effective degradabilities of DM and NDF, resulting in a greater TDN value (56.3%), which was higher than that obtained for rice straw (43.7%). Conclusion: These results provide basic information on the ruminal DM and NDF degradation kinetics of garlic stalk, which would be helpful for the efficient utilization of this by-product in ruminant diets