• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.115-119
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• 2010

Neutral red5 (BR 5) adsorption from aqueous solution was investigated. New solid adsorbent was prepared from paper sludge incinerated at $250^{\circ}C$ during 2 hours. Experiments were carried out, in batch system, to remove RB5 dye from the synthetic waste water. Maximum adsorption of 374.98 mg/g at pH 5, at room temperature and contact time of 80 min was obtained. The Langmuir and Freundlich adsorption models were applied to interpret the equilibrium isotherm. The Freundlich isotherm fits quite well with the experimental data (with highly regression coefficient $R^2$). The incinerated sludge solid samples untreated and treated with BR5 dye were characterized by FT-IR spectrophotometer.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.10
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• pp.986-993
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• 2010

In this study, sorption characteristics of thermally treated activated alumina (AA) for fluoride were investigated. Sorption experiments have been conducted in equilibrium and kinetic batch conditions. Also, effects of solution pH and anions on fluoride removal have been observed. The properties of thermally treated ( $700^{\circ}C$) activated alumina (AA700) and untreated activated alumina (UAA) were compared using field-emission scanning electron microscope, energy-dispersive spectrometry, X-ray diffractometer (XRD) analysis, and Brunauer-Emmett-Teller (BET) analysis. From the experiments using AA thermally treated at different temperatures (100, 300, 500, $700^{\circ}C$), it was found that at high fluoride concentrations (50, 100, 200 mg/L) the sorption capacity of thermally treated AA increased with increasing thermal treatment temperature. At an initial fluoride concentration of 200 mg/L, the sorption capacity of AA700 was 3.67 times greater than that of UAA. The BET analysis showed that the specific surface area of UAA was about 2 times larger than that of AA700. The XRD analysis indicated that UAA was composed of both boehmite (AlOOH) and bayerite ($Al(OH)_3$) while AA700 was $Al_2O_3$. The reason that fluoride sorption capacity of AA700 increased despite of decrease in specific surface area compared to UAA could be attributed to the change of crystal structure. The kinetic sorption test showed that fluoride sorption to AA700 arrived at equilibrium after 24 h. The equilibrium test demonstrated that the maximum sorption capacity of AA700 was 5.70 mg/g. Additional batch experiments indicated that fluoride sorption to AA700 was the highest at pH 7, decreasing at both acidic and basic solution pHs. Also, fluoride sorption to AA700 decreased in the presence of anions such as phosphate, nitrate, and carbonate. This study demonstrated that thermal treatment of AA at high temperature could increase its sorption capacity for fluoride.

• Economic and Environmental Geology
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• v.53 no.5
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• pp.529-542
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• 2020

The cesium (Cs) sorption characteristics of a bead-type polysulfone carrier contained HNO₃-treated bamboo charcoal (3 - 5 mm in diameter) in water system were investigated and its Cs removal efficiency as an adsorbent from water was also identified by various laboratory experiments. From the results of batch sorption experiments, the bead-type polysulfone carrier with only 5% HNO₃-treated bamboo charcoal (P-5NBC) represented the high Cs removal efficiency of 57.8% for 1 hour sorption time. The Cs removal efficiency of P-5NBC in water after 24 hours reaction maintained > 69% at a wide range of pH and temperature conditions, attesting to its applicability under various water systems. Batch sorption experiments were repeated for P-5NBC coated with two cultivated microorganisms (Pseudomonas fluorescens and Bacillus drentensis), which were typical indigenous species inhabited in soil and groundwater. The Cs removal efficiency for two microorganisms coated polysulfone carrier (BP-5NBC) additionally increased by 19% and 18%, respectively, compared to that of only P-5NBC without microorganisms coated. The average Cs desorption rate of P-5NBC for 24 h was lower than 16%, showing the Cs was stably attached on HNO₃-treated bamboo charcoal in so much as its long-term use. The maximum Cs sorption capacity (q_m) of P-5NBC calculated from the Langmuir isotherm model study was 60.9 mg/g, which was much higher than those of other adsorbents from previous studies for 1 h sorption time. The results of continuous column experiments showed that the P-5NBC coated with microorganisms packed in the column maintained > 80% of the Cs removal efficiency during 100 pore volumes flushing. It suggested that only 14.7 g of P-5NBC (only 0.75 g of HNO₃ treated bamboo charcoal included) can successfully clean-up 7.2 L of Cs contaminated water (the initial Cs concentration: 1 mg/L; the effluent concentration: < 0.2 mg/L). The present results suggested that the Cs contaminated water can be successfully cleaned up by using a small amount of the polysulfone carrier with HNO₃-treated bamboo charcoal.

• Economic and Environmental Geology
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• v.44 no.6
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• pp.485-492
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• 2011

Sorption of cyanide on granular activated carbon and attenuation of the cyanide by UV-light over a wide range of conditions such as pH and concentration were investigated through batch experiments. Cyanide uptake by activated carbon is much effective at $[CN]_{ini}$ < 2 mg/L. The sorption of cyanide on activated carbon at pH 7.0 is greater than that of pH 9.0. It is found that the ratio of CN uptake to CN in solution increases at pH 9.0 whereas at pH 7.0 the ratio decreases, suggesting that reactivity of activated carbon increases as a function of pH. The sorption of cyanide rapidly increases during the first 30 min, followed by sharp desorption until 3hr, and then the sorption increases and reaches the maximum sorption during the duration of experiments, implying that the sorption mode could be changed through conformational change during the initial stage of the cyanide uptake by activated carbon. Total amount of cyanide desorbed from the activated carbon during the period of desorption experiments is less than 1.5% of total sorbed cyanide, indicative of strong and stable sorption of cyanide on the activated carbon. The sorption with mixture of activated carbon and Ham-Baek sludge shows less effective on the removal of the cyanide. It is noted that UV-light is much effective on the removal of cyanide but also the attenuation is achieved until $[CN]_{tot}$ is up to 10 mg/L. Our findings demonstrate that both activated carbon and UV-light are very effective on the attenuation of cyanide over a wide range of environmental conditions.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.204-208
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• 2012

Water repellency which affects infiltration, evaporation, erosion and other water transfer mechanisms through soil has been observed under several natural conditions. Water repellency is thought to be caused by hydrophobic organic compounds, which are present as coatings on soil particles or as an interstitial matter between soil particles. This study was conducted to evaluate the characteristics of the water repellent soil and transport characteristics of trace elements within this soil. Capillary height of the water repellent soil was measured. Batch and column studies were accompanied to identify sorption and transport mechanism of trace elements such as $Cu^{2+}$, $Mn^{2+}$, $Fe^{2+}$, $Zn^{2+}$ and $Mo^{5+}$. Difference of sorption capacity between common and repellent soils was observed depended on the degree of repellency. In the column study, the desorption of trace elements and the spatial concentration distribution as a function of time were evaluated. The capillary height was in the repellency order of 0% > 15% > 40% > 70% > 100%. No water was absorbed in soil indicating >70% repellency. Using trace elements, $Fe^{2+}$ and $Mo^{5+}$ showed higher sorption capacity in the repellent soil than in non-repellent soil. The sorption performance of $Fe^{2+}$ was found to be in the repellency order of 40% > 15% > 0%. Our results found that transfer of $Mo^{5+}$ had similar sorption tendency in soils having 0%, 15% and 40% repellency at the beginning, however, the higher desorption capacity was observed as time passes in the repellent soil compared to in non-repellent soils.

• Korean Chemical Engineering Research
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• v.46 no.2
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• pp.436-442
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• 2008

Organic-inorganic hybrid mesoporous anion-exchange resins were prepared for the adsorption of anions from aqueous solutions. The prepared samples were characterized using nitrogen adsorption-desorption measurements, Fourier transform infrared (FTIR) spectroscopy, and elemental analyses. Batch and kinetic experiments were performed to examine the anion-exchange performances of the prepared samples. Among the prepared samples, the hybrid mesoporous anion-exchange resins functionalized with tributylammonium groups showed higher adsorption capacities for perrhenate ions than did the resin functionalized with trimethylammonium groups. The surfactant, hexadecylamine, which had hydrophobic alkyl chains, also showed affinity for hydrophobic perrhenate anions.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.148-148
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• 2013

스퍼터 이온펌프(Sputter Ion Pump)는 주로 화학흡착으로 동작하며 기계적 진동이 없고, 기름 등의 오염 물질을 배출하지 않으며, 수명이 길어 초고청정 진공이 요구되는 표면실험장치, 표면분석계, 입자가속기 등에서 널리 사용 되고 있다. 일정한 지름을 갖는 다수의 원통 양극과 그 양단에 두개의 음극판을 배치시킨 후, 양극과 음극 사이에 수 kV의 전압을 걸고 원통의 축방향으로 자장을 인가하면 페닝 방전이 발생한다. 냉음극에서 방출된 전자는 양극으로 비행하면서 가스를 이온화한다. 이온분자는 가스흡수성 게터재료로 된 음극에 충돌하여 스퍼터링을 일으키며 게터막를 주변에 증착시킨다. 이온 및 중성 가스는 게터 고체막 속에 주입 포획되는 형태로 배기된다. 스퍼터 이온펌프는 $10^{-5}$ Pa 부근에서 최대 배기속도를 가지며, 압력이 낮아질 수록, 특히 $10^{-10}$ Pa영역 이하에서는 그 배기속도가 급격히 저하되며, $10^{-10}$ Pa영역에서는 배기능력을 거의 상실한다. 따라서 스퍼터 이온펌프 단독으로 진공시스템을 배기할 때 도달압력은 $10^{-9}$ Pa 영역에 머무르게 되며, $10^{-10}$ Pa 이하의 극고진공을 얻기 위해서는, $10^{-8}$ Pa 이하의 압력에서 배기 속도가 압력과 무관한 흡착펌프(getter pump)와 이온펌프를 조합하여 사용한다. 본 실험에서는 $600^{\circ}C$ 이상의 온도로 진공로에서 탈개스시킨 진공용기를 배기속도 450, 60, 30, 20, 5, 3 l/s의 6종류의 이온펌프와 배기속도 400 l/s, 100 l/s의 non-evaporable getter (NEG) 펌프를 조합시켜 배기하여 그 배기 특성을 비교하였다. 도달 압력은 이온펌프의 배기속도가 클수록 낮아지는 경향을 보여주었다. 450 l/s 이온펌프와 400 l/s NEG를 조합하여 배기시킬 때 도달 압력은 ~$2{\times}10^{-10}$ Pa을 기록하여 가장 낮았으며, 3 l/s 이온펌프와 400 l/s NEG를 조합하였을 때는 $ 2{\sim}3{\times}10^{-8}$ Pa을 기록하였다. 450 l/s 이온펌프와 400 l/s NEG를 조합한 경우 잔류가스의 대부분이 수소였으나, 3 l/s 이온펌프와 400 l/s NEG의 조합한 경우에는 메탄의 잔류량이 수소 보다 많았다. 이 결과는 메탄을 배기하지 못하는 NEG의 배기 특성을 보완하기 위해서는 일정 배기속도 이상의 이온 펌프가 필요함을 보여준다.

• Economic and Environmental Geology
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• v.48 no.6
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• pp.491-500
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• 2015

Batch experiments were performed to determine the feasibility of the surfactant-enhanced soil washing process at various washing conditions for the Kuwait soil seriously contaminated with the crude oil. The soil was sampled at a dried oil pond in Kuwait and its average TPH concentration was 223,754 mg/kg, which was too high to apply the conventional remediation process. Nine commercialized non-ionic surfactants were used for the batch experiment to measure the surfactant solubility for the crude oil because it was reported that they have worked for the soil remediation. Among them, three surfactants having high crude oil solubility were used for the soil washing experiment. From the result of batch experiment, 5% TritonX-100 washing solution showed the highest TPH removal efficiency (67%) for the crude oil contaminated soil. However, because the residual TPH concentration in the washed soil was still higher than the clean-up level in Kuwait (10,000 mg/kg), the repeated soil washing was performed. After five washings with 2% surfactant solution, the cumulative TPH removal efficiency was higher than 96% and the residual TPH concentration in the soil went down below the clean-up level. To measure the desorption capacity of TritonX-100 remained in the soil after the soil washing, the silica beads and the soil were washed five times with 2% TritonX-100 surfactant solution and then they were washed again with distilled water to detach the surfactant adsorbed on beads or soil. After five washings with surfactant solution, 7.8% and 19.6% of the surfactant was adsorbed on beads and soil, respectively. When additionally washed with distilled water, most of the residual surfactant were detached from beads and only 4.3% of surfactant was remained in soil. From the results, it was investigated that the surfactant-enhanced soil washing process with TritonX-100, Tergitol S-15-7, and Tergitol S-15-9 has a great capability for the remediation of the Kuwait soil seriously contaminated by crude oil (more than 220,000 mg/kg).

• Economic and Environmental Geology
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• v.56 no.2
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• pp.125-138
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• 2023

Most of previous cesium (Cs) sorbents have limitations on the treatment in the large-scale water system having low Cs concentration and high ion strength. In this study, the new Cs sorbent that is eco-friendly and has a high Cs removal efficiency was developed by improving the coal mine drainage treated sludge (hereafter 'CMDS') with the addition of Na and S. The sludge produced through the treatment process for the mine drainage originating from the abandoned coal mine was used as the primary material for developing the new Cs sorbent because of its high Ca and Fe contents. The CMDS was improved by adding Na and S during the heat treatment process (hereafter 'Na-S-CMDS' for the developed sorbent in this study). Laboratory experiments and the sorption model studies were performed to evaluate the Cs sorption capacity and to understand the Cs sorption mechanisms of the Na-S-CMDS. The physicochemical and mineralogical properties of the Na-S-CMDS were also investigated through various analyses, such as XRF, XRD, SEM/EDS, XPS, etc. From results of batch sorption experiments, the Na-S-CMDS showed the fast sorption rate (in equilibrium within few hours) and the very high Cs removal efficiency (> 90.0%) even at the low Cs concentration in solution (< 0.5 mg/L). The experimental results were well fitted to the Langmuir isotherm model, suggesting the mostly monolayer coverage sorption of the Cs on the Na-S-CMDS. The Cs sorption kinetic model studies supported that the Cs sorption tendency of the Na-S-CMDS was similar to the pseudo-second-order model curve and more complicated chemical sorption process could occur rather than the simple physical adsorption. Results of XRF and XRD analyses for the Na-S-CMDS after the Cs sorption showed that the Na content clearly decreased in the Na-S-CMDS and the erdite (NaFeS₂·2(H₂O)) was disappeared, suggesting that the active ion exchange between Na⁺ and Cs⁺ occurred on the Na-S-CMDS during the Cs sorption process. From results of the XPS analysis, the strong interaction between Cs and S in Na-S-CMDS was investigated and the high Cs sorption capacity was resulted from the binding between Cs and S (or S-complex). Results from this study supported that the Na-S-CMDS has an outstanding potential to remove the Cs from radioactive contaminated water systems such as seawater and groundwater, which have high ion strength but low Cs concentration.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.6
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• pp.426-431
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• 2011

The objective of this study was to investigate the virus removal from artificial groundwater using Mg-Fe layered double hydroxide (LDH). Batch experiments were conducted under various experimental conditions to examine bacteriophage T7 removal with Mg-Fe LDH. Results showed that the removal of T7 by Mg-Fe LDH was a fast process, reaching equilibrium within 2~3 hrs. Mg-Fe LDH had the virus removal capacity of $1.57{\times}10^8pfu/g$ with a removal percent of 96%. Results also showed that the effect of solution pH on T7 removal was minimal between pH 6.2 and 9.1. The influence of anions ($SO_4^{2-}$, $CO_3^{2-}$, $HPO_4^{2-}$) on T7 removal was significant due to their competition with bacteriophage at the sorption sites on LDH, while the effect of $NO_3^-$ was negligible. This study demonstrated that Mg-Fe LDH could be applied as adsorbents for virus removal in water treatment.