• Korean Chemical Engineering Research
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• 제57권2호
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• pp.232-238
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• 2019

산업폐수 속의 대표적인 색도유발물질인 염료를 효과적으로 제거하기 위한 생체흡착제로 폴리에틸렌이민을 키틴에 가교결합한 PEI-chitin을 개발하였다. 대표적인 반응성염료인 Reactive Orange 16 (RO16)을 모델염료로 사용하였고, RO16에 대한 PEI-chitin의 흡/탈착 능력을 평가하기 위해 pH의 영향, 등온흡착, 흡착속도론, 탈착 실험을 수행하였다. 그 결과, Langmuir 식에 의해 산출된 최대흡착량은 pH 2에서 266.3 mg/g이었고, 흡착평형에 도달하는 시간은 50 mg/L에서는 약 20분, 100 mg/L에서는 약 60분 그리고 200 mg/L에서는 약 240분으로 평가되었다. 탈착실험은 암모니아/에탄올 혼합용액, NaOH, $NaHCO_3$, $Na_2CO_3$를 용리액으로 이용하여 평가하였으며, 암모니아/에탄올 혼합용액에서 75.24%로 가장 높은 탈착율을 보였다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
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• pp.114-117
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• 2002

Sorption and desorption studies were conducted to evaluate several media as a potential biobarrier for the remediation of groundwater contaminated with hydrophobic organic compounds (HOCs). Pahokee and Bion peats, Devonian Ohio shale, vermicompost, and 50% HDTMA-montmorillonite were used as model sorbents. Sorption and desorption isotherms were determined using the radiolabeled phenanthrene (Phe). Sorption capacity of Phe on several sorbents was in the order Ohio shale > 50% HDTMA-montmorillonite > vermicompost > Pahokee peat. Mineralization kinetics was investigated for Phe-sorbed sorbents using Pseudomonas putida 17484. Among the tested sorbents, active biodegradation of Phe was observed in shale and vermicompost: degradation in shale exhibited little lag time while that in shale showed a significant lag time. Results of this study indicate that sorbents used in this work can be utilized as permeable reactive biobarrier media for the remediation of HOC-contaminated groundwater.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.360-360
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• 2010

Very initial stage of oxidation process of Si (001) surface was investigated using large scale molecular dynamics simulation. Reactive force field potential was used for the simulation owing to its ability to handle charge variation associated with the oxidation reaction. To know the detail mechanism of both adsorption and desorption of water molecule (for simulating wet oxidation), oxygen molecule (for dry oxidation) and their atom constituents, interaction of one molecule with Si surface was carefully observed. The simulation is then continued with many water and oxygen molecules to understand the kinetics of oxide growth. The results show that possibilities of desorption and adsorption depend strongly on initial atomic configuration as well as temperature. We observed a tendency that H atoms come relatively into deeper surface or otherwise quickly desorbed away from the silicon surface. On the other hand, most oxygen atoms are bonded with first layer of silicon surface. We also noticed that charge transfer is only occur in nearest neighbor regime which has been pointed out by DFT calculation. Atomic structure of the interface between the oxide and Si substrate was characterized in atomic scale.

• Applied Science and Convergence Technology
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• 제23권4호
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• pp.169-178
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• 2014

Fluid model based numerical analysis is done to simulate a low damage etch back system for 20 nm scale semiconductor fabrication. Etch back should be done conformally with very high material selectivity. One possible mechanism is three steps: reactive radical generation, adsorption and thermal desorption. In this study, plasma generation and transport steps are analyzed by a commercial plasma modeling software package, CFD-ACE+. Ar + $CF_4$ ICP was used as a model and the effect of reactive gas inlet position was investigated in 2D and 3D. At 200~300 mTorr of gas pressure, separated gas inlet scheme is analyzed to work well and generated higher density of F and $F_2$ radicals in the lower chamber region while suppressing ions reach to the wafer by a double layer conducting barrier.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.205-214
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• 2002

The reaction of gas-phase atomic hydrogen with hydrogen atoms chemisorbed on a silicon surface is studied by use of the classical trajectory approach. Especially, we have focused on the mechanism changes with the hydrogen surface coverage difference. On the sparsely covered surface, the gas atom interacts with the preadsorbed hydrogen atom and adjacent bare surface sites. In this case, it is shown that the chemisorption of H(g) is of major importance. Nearly all of the chemisorption events accompany the desorption of H(ad), i.e., adisplacement reaction. Although much less important than the displacement reaction, the formation of $H_2(g)$ is the second most significant reaction pathway. At gas temperature of 1800 K and surface temperature of 300 K, the probabilities of these two reactions are 0.750 and 0.065, respectively. The adsorption of H(g) without dissociating H(ad) is found to be negligible. In the reaction pathway forming $H_2$, most of the reaction energy is carried by $H_2(g)$. Although the majority of $H_2(g)$ molecules are produced in sub-picosecond, direct-mode collisions, there is a small amount of $H_2(g)$ produced in multiple impact collisions, which is characteristic of complex-mode collisions. On the fully covered surface, it has been shown that the formation of $H_2(g)$ is of major importance. All reactive events occur on a subpicosecond scale, following the Eley-Rideal mechanism. At gas temperature of 1800 K and surface temperature of 300 K, the probability of the $H_2(g)$ formation reaction is 0.082. In this case, neither the gas atom trapping nor the displacement reaction has been found.

• Korean Chemical Engineering Research
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• 제43권4호
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• pp.542-547
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• 2005

생체흡착은 염색폐수로부터 염료 제거를 위한 현재의 처리방법을 교체 또는 보충할 수 있는 유력한 대안이 되고 있다. 본 연구에서는 수용액으로부터 반응성 염료(Reactive Red 4, Reactive Blue 4)를 제거할 수 있는 생체흡착제로서 아미노산 발효공정에서 발생되고 있는 폐기물인 Corynebacterium glutamicum 바이오매스의 활용 가능성에 대해 평가하였다. 염료들의 흡착량은 용액 pH가 감소함에 따라 증가하였는데 이는 산성 pH에서 바이오매스의 표면 작용기는 (+)극성을 띠게 되어 반응성 염료의 (-)극성을 갖는 술폰기(sulfonate group)와 결합하였기 때문인 것으로 사료된다. 접촉시간에 따른 생체흡착속도 실험을 통해 평형에 도달하는 시간은 약 10시간으로 평가되었다. 흡착평형의 수학적인 묘사를 위해 Langmuir 흡착 모델을 적용한 결과, Reactive Red 4, Reactive Blue 4의 최대흡착량은 pH 1에서 112.4 mg/g 및 263.16 mg/g이었으며, pH 3에서는 각각 71.94 mg/g 및 155.88 mg/g이었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.268-268
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• 2013

Water molecules on a Ru(0001) surface are anomalously acidic compared to bulk water. The observation was made by conducting reactive ion scattering, reflection absorption infrared spectroscopy, and temperature-programmed desorption measurements for the adsorption of ammonia onto a water layer formed on Ru(0001). The study shows that the water molecules in the first intact $H_2O$ bilayer spontaneously release a proton to NH3 adsorbates to produce $NH_4{^+}$. However, such proton transfer does not occur for $H_2O$, OH, and H in a mixed adsorption layer or for $H_2O$ in a thick ice film surface.

• 센서학회지
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• 제14권5호
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• pp.343-349
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• 2005

Carbon nitride films were deposited on various substrates for humidity sensors with meshed electrode by reactive RF magnetron sputtering system. As the ratio of injected nitrogen was decreased, the sensitivity of sensor was increased. When the ratio of injected nitrogen was $50{\sim}70%$, the sample showed the best linearity. The sensor impedance changed from $95.4{\;}k{\Omega}$ to $2.1{\;}k{\Omega}$ in a relative humidity range of 5 % to 95 %. The humidity sensors based on silicon wafer revealed higher lineality and faster response than those of alumina or quartz substrates. The adsorption saturation time of the sample was about 80 sec, and its desorption time was about 90 sec.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.263-263
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• 2013

This work examines the dynamic properties of ice surfaces in vacuum for the temperature range of 140~180 K, which extends over the onset temperatures for ice sublimation and the phase transition from amorphous to crystallization ice. In particular, the study focuses on the transport processes of excess protons and chloride ions in ice and their segregative behavior to the ice surface. These phenomena were studied by conducting experiments with a relatively thick (~100 BL) ice film constructed with a bottom $H_2O$ layer and an upper $D_2O$ layer, with excess hydronium and chloride ions trapped at the $H_2O$/$D_2O$ interface as they were generated by the ionization of hydrogen chloride. The migration of protons, chloride ions, and water molecules to the ice film surface and their H/D exchange reactions were measured as a function of temperature using the methods of low energy sputtering (LES) and Cs+ reactive ion scattering (RIS). Temperature programmed desorption (TPD) experiments monitored the desorption of water and hydrogen chloride from the surface. Our observations indicated that both hydronium and chloride ions migrated from the interfacial layer to segregate to the surface at high temperature. Hydrogen chloride gas desorbs via recombination reaction of hydronium and chloride ions floating on the surface. Surface segregation of these species is driven by thermodynamic potential gradient present near the ice surface, whereas in the bulk, their transport is facilitated by thermal diffusion process. The finding suggests that chlorine activation reactions of hydrogen chloride for polar stratospheric ice particles occur at the surface of ice within a depth of at most a few molecular layers, rather than in the bulk phase.

• 한국표면공학회지
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• 제34권5호
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• pp.516-521
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• 2001

Dry etching of Si wafer and $SiO_2$ layers was performed using He/Cl$_2$ mixture plasma by diode-type reactive ion etcher (RIE) system. For Si etching, the Cl molecules react with the Si molecules on the surface and become chemically stable, indicating that the reactants need energetic ion bombardment. During the ion assisted desorption, energetic ions would damage the photoresist (PR) and produce the bad etch Si-profile. Moreover, we have examined the characteristics of the Cl-Si reaction system, and developed the new fabrication procedures with a $Cl_2$/He mixture for Si and $SiO_2$-etching. The developed novel fabrication procedure allows the RIE to be unexpensive and useful a Si deep etching system. Since the etch rate was proved to increase linearly with fHe and the selectivity of Si to $SiO_2$ etch rate was observed to be inversely proportional to fHe.