• 청정기술
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• 제28권3호
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• pp.249-257
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• 2022

Grand canonical Monte Carlo 전산모사 방법에 의하여 77.16 K에서 국부분자배향 모델을 가지는 나노 기공 탄소 흡착제에 대한 질소의 평형 흡착량을 계산하였다. 국부분자배향 모델은 일정한 공간을 가지는 규칙적인 격자에 동일한 크기를 배열하였다. 국부분자배향 영역의 연속적인 평면의 직교(out-of-plane)의 제거에 의해 미세기공을 도입하였고, 기본구조단위의 기울임을 통해 기울어진 기공을 도입하였다. 이런 기공 구조는 틈새형 기공 구조보다 나노기공을 가지는 탄소계 흡착제의 흡착 연구에 보다 현실적인 모델이 된다. 또한 이들 기공 구조에 대해 기공도, 표면적 그리고 제한된 비선형 최적화 기법을 활용하여 기공크기분포에 구하였다. 또한 참고 자료로써 틈새형 기공에서의 등온 평형흡착량도 계산하였다. 틈새형 기공에서는 질소분자의 5배 이상의 기공에서 hysteresis 루프가 관찰되었고, 모세관 응축과 응축의 역과정인 증발이 한 압력에서 한 번에 일어났다. 국부분자배향 기공모델에서는 질소분자의 크기의 6배 큰 기공에서 기저 슬립면, armchair 슬립면 그리고 상호연결된 채널에서 각각 세 가지 연속적인 응축이 관찰되었다. 탈착 과정의 hysteresis 루프에서는 단일 또는 두 압력에서 응축의 반대인 증발이 관찰되었다.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3217-3220
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• 2010

The electronic structures and bonding configuration of histidine on Ge(100) have been investigated with various sample treatments using core-level photoemission spectroscopy (CLPES). Interpretation of the Ge 3d, C 1s, N 1s, and O 1s core level spectra being included in these systems revealed that both the imino nitrogen in the imidazole ring and the carboxyl group in the glycine moiety concurrently participate in the adsorption of histidine on a Ge(100) surface at 380 K. Moreover, we could clearly confirm that the imino nitrogen with a free lone pair in the imidazole group adsorbs on Ge(100) more strongly than the carboxyl group in the glycine moiety by examining systems annealed at various temperatures.

• Bulletin of the Korean Chemical Society
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• 제31권1호
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• pp.100-103
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• 2010

In this study, NO reduction behaviors of copper-loaded mesoporous molecular sieves (Cu/MCM-41) have been investigated. The Cu loading on MCM-41 surfaces was accomplished by a chemical reduction method with different Cu contents (5, 10, 20, and 40%). $N_2/77$ K adsorption isotherm characteristics, including the specific surface area and pore volume, were studied by BET's equation. NO reduction behaviors were confirmed by a gas chromatography. From the experimental results, the Cu loading amount on MCM-41 led to the increase of NO reduction efficiency in spite of decreasing the specific surface area of catalysts. This result indicates that highly ordered porous structure in the MCM-41 and the presence of active metal particles lead the synergistical NO reduction reactions due to the increase in adsorption energy of MCM-41 surfaces by the Cu particles.

• 한국재료학회지
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• 제14권2호
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• pp.157-162
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• 2004

The object of this research is to develop a carbon molecular sieve(below CMS) which can separate selectively to convert mixture gases spout at waste landfill into fuel. And this research is meaningful from the viewpoint of a quality improvement of CH$_4$ gas and an utilization of by-product. CMS was prepared using coconut shell powder as starting material and the effects of activators, temperature and modifier on the reaction were investigated in this research. Also, pore diameter, surface area of CMS and adsorption rate were measured and studied by cahn balance and ASAP2010. Its specific surface area and pore distribution were controlled easily at 800^{\circ}C and adsorption rate was very good. The CMS prepared in this research is shown to be able to separate landfill gases very effectively.

• 상하수도학회지
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• 제22권1호
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• pp.31-38
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• 2008

The primary objective of this study was to evaluate the variation of the molecular size distribution by granular activated carbon (GAC) adsorption. GAC adsorption was assessed by using the rapid small-scale column test (RSSCT) and high-performance size-exclusion chromatography (HPSEC) was used to analyze the molecular size distribution (MSD) in the effluent of GAC column. RSSCT study suggested that GAC adsorption exhibited excellent interrelationship between dissolved organic carbon (DOC) breakthrough and MSD as function of bed volumes passed. After GAC treatment, the nonadsorbable fraction which was about 25percents of influent DOC corresponded to the hydrophilic (HPI) natural organic carbon (NOM) of NOM fractions and was composed entirely of <300 molecular weight (MW) in the HPSEC at the initial stage of the RSSCT operation. The dominant MW fraction in the source water was 1,000~5,000daltons. At the bed volumes 2,500, MW <500 of GAC treated water was risen rather than it of source water. After the bed volumes 7,300 of operation, the MW 1,000~3,000 fraction was closed to about 80percents of DOC found in the GAC influent. The Number-average molecular weight (Mn) value determined using HPSEC for the effluent of GAC column was gently increased as DOC breakthrough progress. The quotient p(Mw/Mn) can be used to estimate the degree of polydispersity was shown greatest value for the GAC effluent at the initial stage of the RSSCT operation.

• 대한화학회지
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• 제40권1호
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• pp.1-10
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• 1996

Gibbs' adsorption isotherms을 이용하여, 계면에서 보조계면활성제 분자의 분자 면적과 계면장력거동에 미치는 ethylene oxide(EO)와 propylene oxide(PO)의 영향을 조사하였다. 일반식 $C_4H_9O(EO)m(PO)_nH$를 갖는 alcohol들의 보조계면활성제로서의 특성을 연구하였는데, 이 alcohol들은 일반적으로 사용되는 보조계면활성제에 비해서 분자량이 크며 계면활성 또한 큰 특성을 갖고있다. EO와PO의 몰수와 이들이 첨가된 상대적 순서는 물/기름 계면에서 alcohol 분자의 분자면적과 계면장력 특성에 큰 영향을 미치는 것을 알 수 있었으며, 다음의 결론을 얻었다. 1) PO는 EO에 비해서 계면흡착 효율은 낮으나, 계면장력 저하 능력은 더 크다. 2) 분자량은 같으나 구조가 다른 분자들, 즉 EO와PO의 첨가 순서만 다른 분자들의 경우는, 계면흡착 효율이 큰 (계면에서의 분자면적이 작은) 분자들이 계면장력 저하 능력이 더 크다. 3) 동일한 친유기에 EO나 PO가 많이 첨가될수록, 분자들의 계면에서의 분자면적은 커지나 계면장력 저하능력도 커진다.

• 한국재료학회지
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• 제14권3호
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• pp.229-234
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• 2004

All the applications of natural zeolites make use of one or more of their physical and chemical properties: adsorption, ion-exchange and related molecular sieve properties, dehydration and rehydration, and siliceous composition. Accordingly, the applications of zeolite have been carried out in the various aspects because of its large cation exchange capacity and adsorption properties. In this paper, the adsorption effect of heavy metal ions in wastewater on zeolite mineral by batch adsorption process is studied. The amounts of adsorbed ions were variable by original pH and ionic concentration, especially original pH of solution had an important effect on the adsorption. In case of low pH solution, e.g. below 3.0, clinoptilolite adsorbed $Pb^{2+}$ ,$ Cd ^{2+ }$ , $Cu^{2+}$ and $Zn^{ 2+}$ , but mordenite almost did not adsorb except $Pb^{2+}$ . Under the same conditions, these ions were more adsorbed on clinoptilolite than on mordenite mineral. The velocity of adsorption was relatively fast and it was confirmed by shaking test that the equilibrium of adsorption could be attained in about one hour. The species of exchangeable cation of zeolite had an effect on its removing ability and zeolite of the sodium-exchanged type was the best.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2217-2221
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• 2011

We investigated the selective deoxyribonucleic acid (DNA) adsorption on layered double hydroxide (LDH) nanoparticles via studying the interaction between positively charged LDH nanoparticle as adsorbent and negatively charged adsorbates such as methyl orange (MO), fluorescein (FL), and DNA strands. The size controlled LDH $(Mg_{0.78}Al_{0.22}(OH)_2(CO_3)_{0.11}{\cdot}mH_2O)$ was prepared by conventional coprecipitation method, followed by the hydrothermal treatment. According to the adsorption isotherms, the adsorbed amounts of MO and FL were similar, however, that of DNA were much larger. The adsorption behaviors were well fitted to Freundlich adsorption model. The concentration dependent adsorption behavior on LDH surface was described in order to verify the selective DNA separation ability. The result showed that the LDH has advantages in selective adsorption of DNA competing with single molecular anions.

• 미생물학회지
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• 제20권4호
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• pp.210-222
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• 1982

Coliphages isolated from Han-River from September 1980 to August 1981 were classified by morphological and physiological characteristics. Effects of soil metrial on the fate of coliphage in nature were investigated. 1. The correlation coefficient between coliphage and E.coli which was host of coliphages in nature was 0.7173 (p=0.004). 2. Coliphage I isolated from Han-River of which DNA molecular weight was $27{\times}10^6$ daltons was identified as $T_1$ phage and coliphage II of which DNA molecular weight $72{\times}10^6$ daltons was classified as $T_5$ phage. 3. Soil material SW was composed of 63.65% silt and 21.92% clay. Clay was consisted of illite, kaolinite and chlorite evenly. Soil material J was composed of 68.92% silt and 11.67% clay. Clay consisted of smectite only. 4. Coliphage was absorbed to soil material J more than soil material SW, and $T_1$ coliphage was absorbed to soil material more than $T_5$ coliphage was. 5. The phage adsorption efficiency to soil material was enhanced at lower pH : the phage adsorption efficiency at pH 4 was 27 time higher than at pH 7. 6. Divalent $(Ca^{2+})\;and\;trivalention\;(Al^{3+})$ enhanced the phage adsorption efficiency to soil material from 4 to 39 and from 17 to 91 times higher than monovalent $ion(Na^+)$, respectively. 7. The concentration of organic compound was inversely related to the phage adsorption efficiency to soil. 8. Adsorption of phage onto soil material, and elution efficiency of elutants was in the order of D.D.W>tap water>river water>seawater. 9. The higher the concentration of organic compound was, the more were adsorbed phages to soil eluted. 10. Coliphages survived longer in sterile soil suspension than in nonsterile soil material suspension.

• 상하수도학회지
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• 제21권1호
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• pp.91-99
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• 2007

It is well-known that the presence of NOM (natural organic matter) in water has a negative effect on removing taste and odor compounds by activated carbon adsorption. Therefore, various means such as enhanced coagulation are applied to reduce the NOM. The presence of taste & odor compounds in drinking water even parts per trillion, is enough to generate customer dissatisfaction. Therefore, the aim of this study was to evaluate carbon usage rate (CUR) for conventional coagulation (CC) and enhanced coagulation (EC) in order to improve the efficiency of adsorption of taste and odor compounds. Also, Effect of CC and EC on molecular weight fraction and the early stage breakthrough of 2-MIB and Geosmin are evaluated. When the enhanced coagulation was adapted for pretreatment for activated carbon adsorption the operation period could be prolonged by 3.5~4 times. CUR for CC was about 2 times greater than CUR for EC and this means that EC has more adsorption capacity than CC. To analyze effect of EC and CC on breakthrough of 2-MIB quantitatively, adsorbed NOM mass was calculated based on unit mass of activated carbon. In the early stage breakthrough of 2-MIB, total adsorbed NOM was 23.72mg/g for CC and 34.56mg/g for EC. Therefore, it is shown that the early breakthrough term of 2-MIB and Geosmin was improved due to increased adsorbability. The low-molecular-weight NOM (500~2000Da) compounds were the most competitive, participating in direct competition with 2-MIB for adsorption site.