• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.221.1-221.1
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• 2011

In this study, we prepared the nitrogen-containing carbon spheres with mesopore processed by a facile polymerization-induced colloid aggregation method including carbonization in order to investigate the characterization and the effect on their carbon dioxide adsorption behaviors. The carbonization temperature was varied in the range of $600^{\circ}C$ to $900^{\circ}C$. The nitrogen contents of the mesoporous carbon sphere were characterized using XPS. The carbon dioxide adsorption capacities of the prepared mesoporous carbon sphere were determined by the amounts of carbon dioxide adsorptions at 298 K and 1.0 atm. The results showed that the prepared mesoporous carbons were highly effective for the carbon dioxide adsorption due to the increasing the affinity of the basic functionalities of adsorbent surface to acidic carbon dioxide. Maximum adsorption capacities of carbon dioxide at $25^{\circ}C$ were achieved up to 106 mg/g.

• Carbon letters
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• 제18권
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• pp.62-66
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• 2016

• Korean Chemical Engineering Research
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• 제45권2호
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• pp.160-165
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• 2007

Low Silica X (LSX) 제올라이트를 합성하여 질소 흡착 반응에 적용하였으며, 기존의 상용화된 질소흡착용 제올라이트와 질소 흡착 성능 및 그 특성을 비교하였다. LSX 제올라이트의 제조 변수로 젤 상태에서의 $Na_2O/(Na_2O+K_2O)$비와 결정화 시간을 고려하였다. $Na_2O/(Na_2O+K_2O)$ 비가 0.75일 때 LSX 제올라이트가 합성됨을 XRD, SEM 분석으로부터 확인하였다. 합성된 LSX 제올라이트는 같은 faujasite 구조를 갖는 NaY나 NaX 제올라이트보다 Si/Al 비가 작고 거의 1에 수렴함을 XRF와 FT-IR 결과로부터 확인하였다. 1A(Li, Na, K), 2A(Mg, Ca, Ba) 족 양이온으로 교환된 LSX 제올라이트에 대해 질소 흡착 테스트를 수행한 결과, 양이온의 전하밀도가 증가할수록 질소 흡착량이 증가하였으며, LiLSX의 경우 질소 흡착량이 가장 많았다. LiLSX의 $Li^+$ 이온 함량을 변화시켜 가며 질소 흡착량을 측정한 결과 Li/Al 비가 0.65 이상일 때, 질소 흡착량이 급격히 증가하였다. $Li^+$ 이온은 제올라이트 세공 내의 supercage(site III, III') 에 위치할 때, 질소 흡착점의 역할을 하였다. LiLSX 제올라이트에 $Ca^{2+}$ 이온을 이온교환시킨 결과 질소 흡착 성능이 더 향상되었는데, Ca/Al의 비가 0.26일 때 질소 흡착 성능이 가장 좋았다. LiCaLSX(Ca/Al=0.26) 제올라이트는 기존의 상용 NaX 제올라이트보다 질소 흡착 성능이 우수하였다.

• Journal of the Korean Wood Science and Technology
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• 제45권2호
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• pp.232-242
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• 2017

The objective of this study was to examine changes in the porosity and internal structure of wood as it goes through the process of saccharification (extraction of fermentable sugars). This study also examined the use of different drying methods to prepare samples for characterization of internal pores, with particular emphasis on the partially disrupted cell wall. Aspen wood flour samples after dilute acid pretreatment followed by enzymatic hydrolysis were examined for nitrogen adsorption. The resulting isotherms were analyzed for surface area, pore size distribution, and total pore volume. Results showed that freeze drying (with sample pre-freezing) maintains the cell wall structure, allowing for examination of saccharification effects. Acid pretreatment (hemicellulose removal) doubled the surface area and tripled the total volume of pores, which were mostly 10-20 nm wide. Subsequent enzymatic hydrolysis (cellulose removal) caused a 5-fold increase in the surface area and a ~ 11-fold increase in the total volume of pores, which ranged from 5 to 100 nm in width. These results indicate that nitrogen adsorption analysis is a feasible technique to examine the internal pore structure of lignocellulosic residues after saccharification. The information on the pore structure will be useful when considering value-adding options for utilizing the solid waste for biofuel production.

• 한국환경과학회지
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• 제29권12호
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• pp.1261-1274
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• 2020

The characteristics of ammonia-nitrogen (NH4+-N) adsorption by a zeolitic material synthesized from Jeju scoria using the fusion and hydrothermal method was studied. The synthetic zeolitic material (Z-SA) was identified as a Na-A zeolite by X-ray diffraction, X-ray fluorescence analysis and scanning electron microscopy images. The adsorption of NH4+-N using Jeju scoria and different types of zeolite such as the Z-SA, natural zeolite, and commercial pure zeolite (Na-A zeolite, Z-CS) was compared. The equilibrium of NH4+-N adsorption was reached within 30 min for Z-SA and Z-CS, and after 60 min for Jeju scoria and natural zeolite. The adsorption capacity of NH4+-N increased with approaching to neutral when pH was in the range of 3-7, but decreased above 7. The removal efficiency of NH4+-N increased with increasing Z-SA dosage, however, its adsorption capacity decreased. For initial NH4+-N concentrations of 10-200 mg/L at pH 7, the adsorption rate of NH4+-N was well described by the pseudo second-order kinetic model than the pseudo first-order kinetic model. The adsorption isotherm was well fitted by the Langmuir model. The maximum uptake of NH4+-N obtained from the Langmuir model decreased in the order of Z-CS (46.8 mg/g) > Z-SA (31.3 mg/g) > natural zeolite (5.6 mg/g) > Jeju scoria (0.2 mg/g).

• Carbon letters
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• 제28권
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• pp.116-120
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• 2018

Nitrogen-doped carbons have attracted much attention due to their novel application in relation to gas storage. In this study, nitrogen-doped porous carbons were synthesized using SBA-15 as a template, polypyrrole as the carbon and nitrogen precursor, and KOH as an activating agent. The effect of the activation temperature ($600-850^{\circ}C$) on the $CO_2$ adsorption capacity of the obtained porous carbons was studied. Characterization of the resulting carbons showed that they were micro-/meso-porous carbon materials with a well-developed pore structure that varied with the activation temperature. The highest surface area of $1488m^2g^{-1}$ was achieved at an activation temperature of $800^{\circ}C$ (AC-800). The nitrogen content of the activated carbon decreased from 4.74 to 1.39 wt% with an increase in the activation temperature from 600 to $850^{\circ}C$. This shows that nitrogen is oxidized and more easily removed than carbon during the activation process, which indicates that C-N bonds are more easily ruptured at higher temperatures. Furthermore, $CO_2$ adsorption isotherms showed that AC-800 exhibited the best $CO_2$ adsorption capacity of $110mg\;g^{-1}$ at 298 K and 1 bar.

• Carbon letters
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• 제8권4호
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• pp.321-325
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• 2007

The oxygen and nitrogen enriched activated carbons were obtained from modification of commercial activated carbon by using nitric acid, sodium hydroxide and urea. Zeta-potentials of modified activated carbons were investigated in relation to copper ion adsorption. The structural properties of modified activated carbons were not so much changed, but the zeta-potentials and isoelectric points were considerably changed. The zeta-potential of nitric acid modified activated carbon was the most negative than other activated carbons in the entire pH region, and the $pH_{IEP}$ was shifted from pH 4.8 to 2.6, resulted in the largest copper ion adsorption capacities compare with other activated carbons in the range of pH 3~6.5. In case of urea modified activated carbon, copper ion adsorption was larger than that of the as-received activated carbon from pH 2 to pH 6.5 even though the $pH_{IEP}$ was shifted to pH 6.0, it was due to the coordination process operated between nitrogen functional groups and copper ion. The adsorption capacity of copper ion was much influenced by zeta-potential and $pH_{IEP}$ of carbon adsorbent.

• 한국환경기술학회지
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• 제19권6호
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• pp.493-502
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• 2018

수계의 조류발생 원인물질인 질소와 인을 제거할 목적으로 수처리용 EM 담체를 개발한 후, 물리적 특성에 대하여 검토한 결과는 다음과 같다. EM 담체를 제조하기 위한 점토 : 제올라이트 : 질석 : 활성탄의 배합비율은 10 : 2.5 : 0.1 : 2, 소성온도는 $700^{\circ}C$가 적합하였다. EM 담체의 공극률과 밀도는 39.98 %와 $1.13kg/m^3$, 질소와 인의 흡착효율은 69.3 %와 38.9 %, 증류수 담체의 공극률과 밀도는 37.80 %와 $1.11kg/m^3$, 질소와 인의 흡착효율은 62.5 %와 37.8 %로 나타났다. EM 담체가 증류수 담체에 비하여 질소의 흡착효율은 6.8 %, 인의 흡착효율은 1.1 %가 크게 나타났다. 담체의 질소와 인에 대한 흡착특성은 Freudlich 흡착등온식으로 표현이 가능하였다. 소성시간의 변화는 EM 담체를 성형할 때 질소의 인의 흡착효율에는 큰 영향을 미치지 못하였으나 담체의 강도에는 영향을 미칠 것으로 판단된다. 질소의 제거효율은 소성시간 4시간, 인의 제거효율은 소성시간 3시간에서 가장 우수하였다.

• Applied Biological Chemistry
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• 제41권4호
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• pp.209-212
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• 1998

Methylan, a polysaccharide produced from Methylobacterium organophilum, was chemically modified by adding diethylaminoethyl (DEAE) group to the backbone of methylan. The structure of DEAE-methylan was determined by measuring its nitrogen content obtained from an elemental analysis. From the analysis of mass spectrum, the DEAE group in DEAE-methylan was also confirmed by determining diethylaminoethene as a separate form of DEAE. Mercury adsorption of DEAE-methylan was higher than that of native methylan. This fact was valid for a variety of pH, reaction times, metal concentrations, and polysaccharide concentrations. In particular, native methylan and DEAE-methylan adsorbed 16% (w/w) and 18% (w/w) for mercury after 30 min at pH 7, respectively. The increase in mercury adsorption of DEAE-methylan may be resulted from mercury adsorption by the lone pair electron of nitrogen atom in DEAE group.

• 한국습지학회지
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• 제20권3호
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• pp.263-271
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• 2018

생활 하수 및 농축산 폐수를 통한 하천으로의 다량의 질소와 인의 유입은 부영양화를 초래하여 하천 자정작용에 악영향을 끼친다. 본 연구에서는 컬럼 실험을 통한 흡착제(활성탄, 제올라이트, 여과사)의 여재층 높이에 따른 암모니아성 질소, 인산염 제거특성을 분석하고, 밀도범함수이론(density functional theory, DFT)를 바탕으로 한 양자역학적 전산 모사를 통해 흡착제와 암모니아성질소($NH_4{^{+}}$)와 인산염($PO_4{^{3-}}$)에 대한 화학적 흡착 거동을 분석하였다. 컬럼 실험 결과, 암모니아성 질소에 대한 제거효율은 제올라이트(95.1%)>활성탄(65.8%)>여과사(10.7%), 인산염의 제거효율은 활성탄(99.6%)>제올라이트(18.8%)>여과사(10.9%) 순으로 나타났다. 제올라이트의 경우, 여재층의 높이에 관계없이 90%이상의 암모니아성 질소에 대한 높은 흡착력을 가졌고, 활성탄의 경우 여재층의 높이가 증가할수록 인과 질소에 대한 높은 흡착효율을 가졌다. DFT를 이용한 흡착제(산화 알루미늄, 활성탄, 여과사)와 영양염류($PO_4{^{3-}}$, $NH_4{^{+}}$)에 대한 흡착거동 분석결과, 제올라이트는 암모니아성 질소($NH_4{^{+}}$)에 대한 높은 흡착에너지(-6.43 eV)를 가졌다. 활성탄의 경우 여과사보다 좁은 HOMO-LUMO 밴드갭을 가져, 전자 이동에 유리한 환경을 조성하여 높은 흡착에너지(-7.10eV)로 영양염류가 제거되는 것을 확인할 수 있었다.