• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2468-2473
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• 2018

Nitrogen-doped activated carbon fibers (ACFs) were prepared by chemical vapor deposition using melamine powder and acetonitrile for introducing quaternary nitrogen on the commercial ACFs, subsequently heated at $950^{\circ}C$ and activated by steam. Adsorption experiments of nitrate in aqueous solution were also conducted to evaluate adsorption capacity of the prepared ACFs using ion chromatography. The amount of introduced nitrogen content and nitrogen species on activated carbon fibers was examined by CHN elemental analyzer and X-ray photoelectron spectroscopy, respectively. As a result, adsorption capacity of quaternary nitrogen-doped ACF (ST-ML-AN-ST) was 0.75 mmol/g, indicating ca. two-times higher than that of untreated ACF (0.38 mmol/g). According to the adsorption data, the Langmuir isotherm model was the best fit. The prepared samples were also regenerated using hydrochloric acid. After regeneration, the adsorption capacity of the nitrogen-doped ACF (ST-ML-AN-ST) showed ca. 80% on average, implying that a portion of nitrates was adsorbed on the prepared ACFs irreversibly.

• 한국환경보건학회지
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• 제27권1호
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• pp.93-99
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• 2001

This study aims at finding out pertinent reaction conditions for treating high concentration ammonia contained in N-chemical factory wastewater with decompressed ammonia stripping method that was designed. And it also tries to investigate adsorption capability of removed ammonia to soil. The results from experiments are as follows ; 1. The removal rate of N $H_3$-N of synthetic wastewater was under 85% at pH 10 with decompressed ammonia stripping method. The reaction time in pressure 360 mmHg at pH 11 and 12 was shorter than in 460 mmHg, and the removal rate of N $H_3$-N with decompressed ammonia stripping method at 9$0^{\circ}C$ was 11~15% higher than air stripping 2. The optimum conditions for decompressed ammonia stripping with synthetic sample were shown as pH 12, temperature 9$0^{\circ}C$, internal reaction pressure 460 mmHg and reaction time 50 minutes. These conditions were applied to treat the wastewater containing organic-N 290.5mg/$\ell$, N $H_3$-N 168.9mg/$\ell$, N $O_2$-N 23.2mg/$\ell$, N $O_3$-N 252.4mg/$\ell$, T-N 735mg/$\ell$. Organic-N turned out to be removed 60%, the removal rate of N $H_3$-N IS 94%, T-N is 50%. But N $O_2$-N and N $O_3$-N were increased with 7.8% and 14.9% respectively. 3. The CO $D_{Sr}$ removal rate in decompressed ammonia stripping reaction was 42% and S $O_4$$^{2-}$ was removed 8.2%. It was turned out caused with higher pH and thermolysis. 4. In soil adsorption of ammonia desorbed from the decompressed stripping process of wastewater, the recovery rate was 76% in wet soil.

• 한국환경과학회지
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• 제10권6호
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• pp.451-459
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• 2001

Adsorption characteristics of triadimefon and diniconazole(pesticide) by natural zeolite($CLI_N$) and several synthetic zeolites were Investigated. The synthetic zeolites used En this study were as follows: Faujasite synthesized from coal fly ash($FAU_F$); Zeolite synthesized from the mixture of FAU and Na-Pl synthesized from the ratio of Cheju scoria 6 to coal fly ash 4 by weight($(FAU + Na-Pl)_{SF}$); waste fluid catalytic cracking catalyst($FCC_W$). The distribution coefficient, $K_D$ and Freundlich constant, $K_F$ decreased in the fellowing sequence : $FCC_W ＞ FAU_F ＞ (FAU + Na-Pl)_{SF} ＞CLI_N$ among the zeolites. The distribution coefficient and the adsorption capacity of $(FAU + Na-Pl)_{SF}$ for pesticides were 4.4 and 2.6 times higher for triamefon, and 2.0 and 2.4 times higher for diniconazole than those of $CLI_N$, respectively.

• 한국환경보건학회지
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• 제21권4호
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• pp.17-23
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• 1995

As a basic experiment to develope biological pretreatment proces~ in water treatment, the experiments on biodegradability and isothermal adsorption of activated carbon were performed on refractories such as humic acid, $NH_3-N$, phenol and ABS which caused the problems in drinking water treatment. Also, the treatabilities on humic acid were examined in the continuous flow type reactors. The removal efficiencies of humic acid, $NH_3-N$, phenol and ABS in the biodegradable experiments for 5 days were 20.1%, 73.4%, 91.7% and 97.5%, respectively. In the isothermal adsorption test of refractories on activated carbon to be used as a media in the continuous flow type reactors, ABS and phenol are adsorbed easily, but humic acid and $NH_3-N$ are difficult to be done. The removal efficiencies of humic acid in granular activated carbon(GAC) reactor were about 7-8% higher than in biological activated carbon(BAC) reactor. The removal efficiencies of humic acid in biological fluidized bed(BFB) reactor were about 30% in GAC media, but were almost zero in sea sand media.

• 청정기술
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• 제30권2호
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• pp.123-133
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• 2024

대기 중에 존재하는 저농도 CH₄을 제거를 위한 흡착제 개발을 위해서 Zeolite Template Carbon (ZTC)을 합성하였다. 탄소 전구체가 ZTC 합성에 미치는 영향을 알아보기 위해서, CH₄와 C₂H₂를 탄소 전구체로 사용하여 ZTC를 합성하였으며, 또한 이온 교환에 사용된 금속의 영향을 알아보기 위해서 CaCl₂와 LiCl을 사용하여 이온교환한 Y Zeolite을 Template로 사용하여 ZTC를 합성하였다. 탄소 전구체 간의 비교에서는 C₂H₂가 CH₄ 보다 더 높은 탄소 수율을 보였으며, 또한 미세기공이 발달한 ZTC를 합성하였다. 이는 C₂H₂의 분자 동역학적 크기(Kinetic Diameter) (3.3 Å)가 CH₄의 분자 동역학적 크기(Kinetic Diameter) (3.8 Å)보다 더 작기 때문에, 제올라이트 템플릿의 미세 기공 내부의 깊숙한 곳에서부터 탄소 침착을 가능하였기 때문인 것으로 판단된다. 이온 교환에 사용된 금속 전구체 간의 비교에서는 CaCl₂ 기반의 ZTC가 LiCl을 기반의 ZTC보다 미세 기공이 발달한 것을 확인하였는데, 이온 교환된 Ca가 탄소 전구체에 의한 Pore Blocking을 억제해서 기공 내부로 탄소 전구체가 들어 갈 수 있게 한 덕분으로 판단된다. 합성된 ZTC를 이용하여, 298 K에서의 N₂와 CH₄의 흡착 등온선을 측정하였는데, 전체적으로 CH₄의 흡착량이 N₂보다는 높다는 것을 확인하였다. 또한 CaY 기반으로 C₂H₂를 이용하여 합성한 ZTC 샘플이 N₂와 CH₄ 흡착량이 가장 높았지만, 흡착 공정 설계의 중요한 인자인 CH₄와 N₂의 흡착 비율 기준으론 CH₄으로 합성한 샘플이 가장 높게 나왔다. 이는 N₂ 흡착과 관련 깊은 초미세기공이 덜 발달하여, N₂의 흡착량을 줄임으로서 오히려 CH₄/N₂ 분리도를 높게 해 주었기 때문으로 판단된다.

• 공업화학
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• 제9권5호
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• pp.661-666
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• 1998

고시리카제올라이트 (HSZ), 거대망상수지입자(MR) 및 입상활성탄(GAC)에 의한 수용액중의 12가지 아민유도체의 평형흡착 실험 데이터와 Freundlich, Langmuir, Toth, Redlich-Peterson 식의 인자들을 각각 구하였다. 아민류의 흡착특징에 있어서는 고시리카제올라이트는 unfavourable, 입상활성탄은 favourable로 비선형이나, 거대망상수지흡착제는 선형관계의 특성을 나타내며, 변수가 2개인 Freundlich 식과 3개인 Redlich-Peterson 흡착등온식에 잘 일치하였다. HSZ, MR, GAC에 의한 아민류의 흡착능은 방향족>1급아민>2급아민 순이었으며, Freundlich상수 k와 n의 곱인 (k n)값은 HSZ와 MR 및 GAC에서 아민류의 끓는 점 $T_B$, 몰부피 $V_m$, 그리고 해리상수 $pK_a$에 비례하여 증가하였다.

• 멤브레인
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• 제29권5호
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• pp.237-245
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• 2019

암모니아성 질소($NH_4-N$)는 산업 폐수, 농업 및 축산 폐수에 포함되어 있으며 인과 함께 수질의 부영양화를 일으키는 물질로 잘 알려져 있다. 또한 망간(Mn)과 비소(As)는 광산 처리수 등에 포함되어 있으며, 수질 오염의 원인 물질로 알려져 있다. 천연 제올라이트는 수중에서 암모니아성 질소를 제거하는데 사용되고 있지만 낮은 흡착능력을 가진다. 이러한 천연 제올라이트의 낮은 흡착능력을 개선하기 위해 $Na^+$, $Ca^{2+}$, $K^+$, $Mg^{2+}$로 이온 치환을 진행하였다. 암모니아성 질소($NH_4-N$)의 흡착량과 제거율은 $Na^+$로 이온 치환된 제올라이트에서 0.66 mg/g과 89.8%로 가장 높은 값을 보였다. 이온 치환된 제올라이트를 이용하여 Mn과 As의 흡착실험을 진행하였다. $Mg^{2+}$로 이온 치환된 제올라이트에서 Mn과 As의 높은 흡착량과 제거율을 보였다.

• 펄프종이기술
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• 제34권3호
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• pp.9-16
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• 2002

The adsorption characteristics and surface energetics of hydrophobically modified MCC have been investigated by the inverse gas chromatography technique at infinite dilution. The thermodynamic parameters of adsorption, ΔG, ΔH and ΔS, for n-alkanes were determined at infinite dilution. Heats of adsoption of the n-alkanes increased as the level of hydrophobic modification increased. The hydrophobically modified MCC also showed greater entropy of adsorption indicating restricted mobility of the adsorbed n-alkanes. The acid/base characteristics of the MCC were evaluated using polar probes. As the hydrophobicity of MCC increased, the basisity of the MCC decreased.

• Bulletin of the Korean Chemical Society
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• 제31권1호
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• pp.162-167
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• 2010

We investigated the adsorption and desorption characteristics of benzene molecules on $Si(001)-2{\times}n$ surfaces using a variable-low temperature scanning tunneling microscopy. When benzene was adsorbed on a $Si(001)-2{\times}n$ surface at a low coverage, five distinct adsorption configurations were found: tight-binding (TB), standard-butterfly (SB), twisted-bridge, diagonal-bridge, and pedestal. The TB and SB configurations were the most dominant ones and could be reversibly interconverted, diffused, and desorbed by applying an electric field between the tip and the surface. The population ratios of the TB and SB configurations were affected by the benzene coverage: at high coverage, the population ratio of SB increased over that of TB, which was favored at low coverage. The desorption yield decreased with increasing benzene coverage and/or density of vacancy defect. These results suggest that the interaction between the benzene molecules is important at a high coverage, and that the vacancy defects modify the adsorption and desorption energies of the benzene molecules on Si(001) surface.

• 대한화학회지
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• 제16권4호
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• pp.241-248
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• 1972

영일 bentonite를 여러 농도의 NaOH, $Na_2SO_4 또는 NaHSO_4 용액으로 처리온도와 처리 시간을 달리하여 처리한 시료의 Methylene Blue 흡착력을 조사하였다. NaHSO_4용액으로 처리했을 경우에는 Methylene Blue 흡착력이 거의 개선되지 않았다. Na_2SO_4$ 용액으로 처리했을 경우에는 1N 용액으로 $100^{\circ}C$에서 2시간 처리했을 경우가 가장 좋았으며, 원시료의 3배의 흡착력을 나타내었다. 더 높은 농도와 더 높은 온도로 처리하면 Faujasite이 생성됨을 알았다. NaOH용액으로 처리했을 경우의 가장 좋은 처리조건은 1N, 1hr, $100^{\circ}C$이고 원시료의 3.3배의 흡착력을 나타내었다. 더 높은 농도와 더 높은 온도인 경우에는 hydroxysodalite이 생성됨을 알았다.