• Mycobiology
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• 제42권3호
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• pp.249-255
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• 2014

We evaluated a more practical and cost-effective immobilization carriers for ethanol production using the yeast Saccharomyces cerevisiae. Three candidate materials-rice hull, rice straw, and sawdust-were tested for their cell-adsorption capacity and operational durability. Derivatizations of rice hull, rice straw, and sawdust with the optimal concentration of 0.5 M of 2-(diethylamino)ethyl chloride hydrochloride (DEAE HCl) resulted in > 95% adsorption of the initial yeast cells at 2 hr for DEAE-rice hull and DEAE-sawdust and in only approximately 80% adsorption for DEAE-rice straw. In addition, DEAE-sawdust was found to be a more practical carrier for immobilizing yeast cells in terms of operational durability in shaking flask cultures with two different speeds of 60 and 150 rpm. Furthermore, the biosorption isotherms of DEAE-rice hull, -rice straw, and -sawdust for yeast cells revealed that the $Q_{max}$ of DEAE-sawdust (82.6 mg/g) was greater than that of DEAE-rice hull and DEAE-rice straw. During the 404-hr of continuous column reactor operation using yeast cells immobilized on DEAE-sawdust, no serious detachment of the yeast cells from the DEAE-sawdust was recorded. Ethanol yield of approximately 3.04 g/L was produced steadily, and glucose was completely converted to ethanol at a yield of 0.375 g-ethanol/g-glucose (73.4% of the theoretical value). Thus, sawdust is a promising practical immobilization carrier for ethanol production, with significance in the production of bioethanol as a biofuel.

• 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.

• Carbon letters
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• 제28권
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• pp.87-95
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• 2018

This study examined the influence of operating parameters on the electrosorptive recovery system of lithium ions from aqueous solutions using a spinel-type lithium manganese oxide adsorbent electrode and investigated the electrosorption kinetics and isotherms. The results revealed that the electrosorption data of lithium ions from the lithium containing aqueous solution were well-fitted to the Langmuir isotherm at electrical potentials lower than -0.4 V and to the Freundlich isotherm at electrical potentials higher than -0.4 V. This result may due to the formation of a thicker electrical double layer on the surface of the electrode at higher electrical potentials. The results showed that the electrosorption reached equilibrium within 200 min under an electrical potential of -1.0 V, and the pseudo-second-order kinetic model was correlated with the experimental data. Moreover, the adsorption of lithium ions was dependent on pH and temperature, and the results indicate that higher pH values and lower temperatures are more suitable for the electrosorptive adsorption of lithium ions from aqueous solutions. Thermodynamic results showed that the calculated activation energy of $22.61kJ\;mol^{-1}$ during the electrosorption of lithium ions onto the adsorbent electrode was primarily controlled by a physical adsorption process. The recovery of adsorbed lithium ions from the adsorbent electrode reached the desorption equilibrium within 200 min under reverse electrical potential of 3.5 V.

• Composites Research
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• 제29권5호
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• pp.256-261
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• 2016

본 연구에서는 습식공정을 이용한 Pitch계 활성탄소섬유와 바인더 섬유를 이용하여 필터 페이퍼를 제조하였다. 필터 페이퍼 내 바인더 섬유의 함량이 기공특성에 미치는 영향을 알아보기 위해 77 K에서 질소 흡착 등 온선과 주사 전자 현미경을 통해 흡착특성을 비교 분석하였다. Pitch계 활성탄소섬유와 바인더 섬유와의 최적 비율은 70:30 비율로 가장 균일한 기공 및 결합력이 좋은 페이퍼의 모습을 보였으며, 바인더 섬유의 함량이 적을수록 높은 비표면적 값을 확인하였다. Pitch계 활성탄소섬유와 바인더 섬유의 종류와는 상관없이 70:30 비율에서 최적의 페이퍼가 제조되었으며, $650.4m^2/g$의 비표면적 값과 86.9%의 유해가스 제거율을 확인하였다. 또한 필터 페이퍼의 평균 기공 크기 분포는 바인더 섬유의 영향을 받지 않는 것으로 관찰되었다.

• Advances in environmental research
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• 제6권3호
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• pp.173-187
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• 2017

Heavy metals, such as vanadium, are some of the most toxic types of water contaminants. In this study, vanadium was removed using a new composite adsorbent called BAZLSC. The impacts of pH and initial concentration of vanadium(V) on the elimination effectiveness of this metal by using BAZLSC were investigated in the first step of the study. Vanadium removal increased as pH increased to 3-3.5, and initial concentration increased to 60-70 mg/L. The removal efficiency then decreased. Central composite design and response surface methodology were employed to examine experimental data. Initial concentration of V ($mg.L^{-1}$), pH, and dosage of adsorbent (g/L) were the independent factors. Based on RSM, the removal effectiveness of vanadium was 86.36% at the optimum of initial concentration (52.69 mg/L), pH (3.49), and adsorbent dosage (1.71 g/L). Also adsorption isotherm investigations displayed that the Freundlich isotherm could explain vanadium adsorption by BAZLSC better than the Langmuir isotherm. Beside them, desorption studies showed sorption was slightly diminished after six continuous cycles.

• 대한화학회지
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• 제33권4호
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• pp.350-356
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• 1989

타르, 니코틴 등 몇 가지 연초 에어로솔 성분의 흡착거동을 해석한 결과 비교적 저비점 피흡착질의 흡착률은 축적 동공부피의 증가와 더불어 증가하였다. 반면 비교적 고비점 피흡착질의 흡착률은 보다 작은 반경의 동공부피가 증가할수록 감소하였다. 여기에 사용된 흡착제는 활성탄, 실리카겔, 알루미나 및 활성백토이었다. 비표면적이 큰 흡착제가 보다 큰 흡착률을 가진다는 일반적인 경향은 고비점 피흡착질에 대해서는 성립되지 않았다. 이상의 결과는 위의 흡착거동을 탈착등온식을 기초로 하여 동공부피분포와 관련시켜 검토하므로써 얻어진 것이다.

• 한국식품영양과학회지
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• 제30권2호
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• pp.344-349
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• 2001

클로렐라는 건강보조식품으로 이용될 뿐만 아니라 수용액상에서 중금속 제거를 위한 흡착제로 많이 연구되고 있다. 본 연구에서는 클로렐라를 이용하여 수도물의 소독제로 사용되는 염소의 제거 효과를 확인하였으며 그 결과를 녹차, activated carbon과 비교하였다. 수용액상에서 pH와 초기염소의 농도가 염소의 제거에 미치는 영향을 조사하였다. 최적의 제거 pH는 10이었으며, 염소의 제거량은 초기 염소의 농도가 1.62 g/L까지 증가함에 따라 2.46 mg/mg까지 증가하였다. 녹차의 경우 초기 염소의 농도가 1.0 g/L 이상으로 증가하여도 제거량은 약 1.5mg/mg 정도에 더 이상 증가하지 않았다. 클로렐라와 녹차에 의한 염소의 제거 결과는 Langmuir 흡착모델과 Freundlich 흡착모델에 대단히 잘 맞았으며 Langmuir 흡착모델에 의한 클로렐라의 최대 흡착량은 녹차와 activated carbon의 최대 흡착량에 비하여 약 2배로 나타나 클로렐라의 염소의 제거효능이 매우 우수한 것으로 사료되었다.

• 한국세라믹학회지
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• 제55권3호
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• pp.261-266
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• 2018

Hollow or bumpy ZnO structures with micrometer-size features have been investigated as photocatalysts for water purification due to their high surface area available for reaction with harmful organic molecules and relatively large size for easy separation after finishing the photocatalytic reaction. In this study, selective synthesis of ZnO hollow or crumpled microspheres was performed using a simple and versatile ultrasonic spray pyrolysis process with various zinc precursors. The morphologies, phases, specific surface areas, and optical properties of the microspheres were characterized using X-ray diffraction, scanning electronic microscopy, nitrogen adsorption-desorption isotherms, and UV-vis spectroscopy. In addition, the mechanism underlying the formation of different morphologies and their photocatalytic activities were systematically investigated.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.159.2-159.2
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• 2011

In this study, we prepared the activated graphite nanofibers (A-GNFs) via chemical activation with KOH reagent. The effect of A-GNFs on the surface and textural properties of Ni-loaded graphite nanofibers (Ni/GNFs) was investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), and Brunauer-Emmett-Teller (BET). The textural properties of samples were investigated by $N_2$/77K adsorption isotherms. The electrochemical performances were investigated by cyclic voltammetry. As a results, the electrochemical performances of Ni/GNFs were improved with usage of A-GNFs. This could be interpreted by the high specific surface area and large total pore volume of the A-GNFs.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.158.1-158.1
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• 2011

In this work, we prepared ultramicroporous carbons (UC) prepared by pyrolyzing poly(vinylidene fluoride) with different carbonization temperatures, and investigated the hydrogen storage behaviors. The surface functional groups and specific elements of UC were confirmed by Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), respectively. Textural properties were analyzed using $N_2$ adsorption isotherms at 77 K. The hydrogen storage capacity of the UC samples were investigated by BEL-HP at 298 K/10 MPa. From the results, it was found that the hydrogen storage capacity was enhanced with increasing of specific surface area, resulting from the formation of ultramicropore on the UC.