• Advances in environmental research
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• 제2권3호
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• pp.245-260
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• 2013

Biosorption represents a technological innovation as well as a cost effective excellent remediation technology for cleaning up radionuclides from aqueous environment. In the present study, a bacteria strain FB12 with high adsorption rate of uranium ion was isolated from the vicinity of the nuclear power plant. It was tentatively identified as Bacillus sp.FB12 according to the 16S rDNA sequencing. Efforts were made to further improve the adsorption rate and genetic stability by UV irradiation and UV-LiCl cooperative mutagenesis. The improved strain named Bacillus sp.UV32 obtains excellent genetic stability and a high adsorption rate of 95.9%. The adsorption of uranium U (VI) by Bacillus sp.UV32 from aqueous solution was examined as a function of metal ion concentration, cell concentration, adsorption time, pH, temperature, and the presence of some foreign ions. The adsorption process of U (VI) was found to follow the pseudo-second-order kinetic equation. The adsorption isotherm study indicated that it preferably followed the Langmuir adsorption isotherm. The thermodynamic parameters values calculated clearly indicated that the adsorption process was feasible, spontaneous and endothermic in nature. These properties show that Bacillus sp.UV32 has potential application in the removal of uranium (VI) from the radioactive wastewater.

• 한국식품과학회지
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• 제22권5호
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• pp.530-532
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• 1990

옥수수의 장기저장을 위한 기초연구로서 건조옥수수 또는 침지옥수수를 $80^{\circ}C$에서 삶고 건조한 다음 이들 시료의 수분흡습성질을 저장온도 $25^{\circ}C$, 상대습도 23-97%에서 비교하였다. 건조옥수수는 상대습도 23% 이하에서, 침지옥수수는 33% 이하에서 탈습현상을 보였고, 상대습도 97%에서 건조옥수수는 192시간 후에, 삶은 옥수수는 288시간 후에 곰팡이가 발생되었다. 동일한 수분활성도에서 침지옥수수는 가장 높은 평형수분함량을 보였다. 단분자막층 수분함량과 흡습열은 침지옥수수의 경우가 가장 높았으며, 등온안정곡선으로부터 얻은 저장안정의 상대습도는 60-70%이었다.

• 한국환경과학회지
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• 제1권2호
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• pp.59-69
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• 1992

In order to predict the distribution of chemical species of copper and cadmium in water, conditional stability constant and complexation capacity between copper or cadmium and natural aquatic sediment have been determined in a shallow lake in Haman, Kyungnam. Kinetic parameters were calculated by Langmuir isotherm equation. Conditional stability constant was log $K_{cuSed}=4.78 and log K_{cdSed}=4.45$. Complexation capacity was $1.70{\times}10^{-4}$moles/g for copper and $5.54{\times}10^{-5}$moles/g for cadmium. Accuracy of experimental values of conditional stability constant was checked by comparing the calculated concentration of the metals with the measured one. Relatively good agreement between these values was obtained. Relative errors were 8.9% for copper and 6.5% for cadmium. Data of the measured conditional stability constant were put into data base of MINEQL computer program, and concentration of various chemical species of copper and cadmium in a model aquatic system was calculated. Aquatic sediment was associated with copper at the concentration of $10^{-5M}(0.059g/\ell)$10-5M(0.059g/l) and with cadmium at the concentration of $10^{-6M}(0.018g/\ell)$, and it significantly influenced on the distribution of chemical species of the metals. This result showed that prediction of chemical species of the heavy metals in an aquatic system should be taken into account the influence of the sediment.

• 한국가구학회지
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• 제20권6호
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• pp.560-565
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• 2009

It is known that heat treatment decreases the hygroscopicity of wood. Thus heat-treated wood is good for outdoor construction due to its improved dimensional stability. This study is to investigate the hygroscopicity and discoloration of spruce and birch boards heat-treated above $190^{\circ}C$. The equilibrium moisture contents (EMCs) at all relative humidities decreased with the increase of heat treatment temperature and/or time for both spruce and birch. It was revealed that heat-treatment temperature affected more on the hygroscopicity thaan heat-treatment time. The average basic densities decreased for the spruce specimens, but increased for the birch specimens with an increase of the treatment time and/or temperature. The same heat treatment condition (190-8) made the birch specimens darker than the spruce specimens.

• 한국세라믹학회지
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• 제32권8호
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• pp.901-908
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• 1995

In aqueous slurry processing of silicon nitride, the interaction of dispersant and binder used as polymeric processing additives on the silicon nitride particle surface was studied to identify the effect of these processing polymeric additives on the ceramic powder processing. The adsoprtion isotherm study of anionic organic molecule as dispersant and nonionic organic molecules as binder of silicon nitricde was studied to investigate the effect of these processing organic additives on the physicochemical properties of silicon nitride particles. As anionic molecule adsorbed onto silicon nitrice surface, the IEP of silicon nitride shifted toward acidic pH and changed the stability of silicon nitride particle. However, the adsorption of binder as nonionic organic molecule onto silicon nitride surface did not changed the IEP but caused the decrease of electrostatic potentials of silicon nitride. These distinctive adsorption behaviors of organic additives on silicon nitride particles can be closely correlated to the stability of silicon nitride particles suspended in aqueous media.

• 한국물환경학회지
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• 제22권1호
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• pp.172-176
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• 2006

Fe(III)-Coated Star Fish (ICSF) was prepared by reaction of calcined Star Fish (SF) with Fe(III) solution at an elevated temperature. To investigate the stability of ICSF at acidic condition, dissolution of Fe was studied at pH 2 as a function of time. Extracted iron was negligible over the entire reaction time. This stability test suggests the applicability of ICSF in the treatment of wastewater even at low pH. Adsorption capacity of Cu(II) onto SF and ICSF was investigated in a batch and a column test. In the pH-edge adsorption, adsorption of copper onto SF and ICSF was quite similar over the entire pH range due to the presence of an important amount of Fe in SF itself. From the adsorption isotherm obtained with variation of the concentration of Cu(II), ICSF showed 1.6 times greater adsorption capacity than SF. Also, ICSF showed a greater removal capacity of Cu(II) in the column test.

• 한국식품과학회지
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• 제19권3호
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• pp.206-211
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• 1987

건조김의 품질을 향상시키고 저장안정성을 높이기 위하여 수세물량을 달리하여 건조김을 제조하고$30^{\circ}C$와 $5^{\circ}C$에서 포장방법별로 6개월동안 저장하면서 품질변화 특성을 조사하였다. 건조김의 단분자층 수분함량을 $5^{\circ}C$와 $25^{\circ}C$에서 구해본 결과 각각 7.4%와 6.4%로 나타났다. 저장효과는 원료김을 충분한 물로 수세하여 수분함량을 단분자층 이하로 낮추어 가능한한 낮은 온도에서 저장하는 것이 바람직 하였으며 포장방법에 있어서는 진공포장이 함기포장에 비하여 품질유지가 다소 좋은 것으로 나타났다.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1996년도 제11차 KACG 학술발표회 Crystalline Particle Symposium (CPS)
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• pp.129-153
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• 1996

In aqueous slurry processing of silicon nitride, the interaction of dispersant and binder on the surface of particles was studied to identify the effect of these additives on ceramic powder processing. Polymethacrylic acid (PMAA) and polyvinyl alcohol (PVA) were used as dispersant and binder, respectively. the adsorption isotherms of PMAA and PVA for the silicon nitride suspension were determined, while the adsorption of PMAA was differentiated in the mixed additive system by ultraviolet spectroscopy. These experiments were done in order to investigate the effect of these organic additives on the physicochemical properties of silicon nitride suspensions. The electrokinetic behavior of silicon nitride was subsequently measured by electrokinetic sonic amplitude (ESA). As PMAA adsorbed onto silicon nitride, the isoelectric point (pHicp) shifted from pH=6.7 to acidic pH, depending on the surface coverage of PMAA. However, adsorption of PVA did not change the pHicp of suspensions, but did decrease the surface potential of silicon nitride moderately. The rheological behavior of silicon nitride suspensions was measured to assess the stability of particles in aqueous media, and was correlated with the electrokinetic behavior and adsorption isotherm data for silicon nitride.

• 한국물환경학회지
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• 제22권2호
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• pp.328-332
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• 2006

Fe(III)-impregnated activated carbon (Fe-AC) was applied in the treatment of synthetic wastewater containing Cu(II). To investigate the stability of Fe-AC at acidic condition, dissolution of Fe was studied with a variation of solution pH ranging from 2 to 4. Fe-AC was unstable at pH 2, showing a gradual increase of the dissoluted Fe as reaction time increased, while negligible amount of Fe was dissoluted above pH 3. This stability test suggests the applicability of Fe-AC in the treatment of wastewater above pH 3. Adsorption capacity of Cu(II) onto activated carbon (AC) and Fe-AC was investigated in a batch and a column test. In the adsorption kinetics, rapid adsorption of Cu(II) onto AC and Fe-AC was noted at initial reaction time and then reached a near complete equilibrium after 6 hrs. Adsorption trends of Cu(II) onto AC and Fe-AC were similar, showing an increased Cu(II) adsorption at higher pH. Compared with AC, Fe-AC showed a greater Cu(II) adsorption over the entire pH range studied in this research. From the adsorption isotherm obtained with variation of the concentration of Cu(II), the maximum adsorption capacity was identified as 61,700 mg/kg.

• 한국지하수토양환경학회지:지하수토양환경
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• 제12권4호
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• pp.78-85
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• 2007

본 연구에서는 화학회사에서 발생되는 연마분진 폐기물의 흡착제로서의 재이용성을 평가하였다. 연마분진을 $550^{\circ}C$에서 하소시킴으로서 유기불순물을 제거하였다. 연마분진내의 주요 무기물은 Al이었으며 하소 후 Al 함량은 29.09%에서 52.73%로 증가되었다. 하소 후 시료의 안정성 평가를 실시한 결과 pH 2.0의 강한 산성조건에서도 모든 중금속들의 용출량은 0.3 mg/L 이하로 나타났다. pH 변화에 따른 As(V) 흡착실험에서 As(V)의 흡착효율은 전형적인 음이 온형 흡착경향을 보였다. 하소된 연마분진의 주입량 변화에 따른 As(V)의 등온흡착 실험결과는 Freundlich 등온흡착식이 Langmuir 등온흡착식보다 상대적으로 잘 표현되는 것으로 나타났다. Freundlich 등온흡착상수 K와 1/n은 각각 4.2442와 0.3161로 얻어졌다. Langmuir 등온흡착식으로 얻어진 하소된 연마분진의 최대 As(V) 흡착량은 13.25 mg/g이었다. 이러한 연구결과, 하소된 연마분진은 안정도 및 As(V) 흡착능을 고려하였을 때 재이용성이 양호한 흡착제로 나타났다.