• Journal of the Korean Geotechnical Society
• /
• v.23 no.7
• /
• pp.47-55
• /
• 2007

In this study, applicability of electrical conductivity monitoring technique for containment barrier such as soil-bentonite wall was evaluated. Laboratory tests including permeability tests and column tests were performed to understand variations in electrical conductivity at different bentonite contents, hydraulic conductivities, and heavy metal concentrations. The electrical conductivity of compacted soil-bentonite mixtures was found to increase proportionally with bentonite content. Accordingly, the hydraulic conductivity of compacted soil-bentonite mixtures which decreases linearly with increasing bentonite content was found to have an inversely proportional relationship with the electrical conductivity. In column tests, electrical conductivity breakthrough curves and concentration breakthrough curves were simultaneously obtained. These results indicated that electrical conductivity measurement can be an effective means of detecting heavy metal transport at the desired locations within barriers and verifying possible contaminant leakage. Experimental results obtained from this study showed that the electrical conductivity measurement can be a promising tool for monitoring of containment barrier.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.09a
• /
• pp.122-125
• /
• 2004

본 연구는 친환경적 유기흡착제로서 휴믹물질의 활용성을 평가하기 위한 기초 연구로서 Peat moss에서 추출된 불용성 휴믹성분인 피트휴민(p-Humin)을 충진한 컬럼을 이용하여 카드뮴과 구리이온에 대한 파과곡선을 얻었고, 각 금속이온에 대한 제거능을 비교해 보았다. 카드뮴의 경우, 파과시간은 7.5 hr, 77 BV로 나타났으며, 구리의 경우, 7.3 hr, 76 BV으로 나타났다. Thomas model로부터 구한 최대 흡착량은 구리가 44.66 mg/g로 카드뮴의 41.61 mg/g보다 높게 나타났다. 0.05 N HNO$_3$를 이용한 탈질실험 결과, 각 중금속에 대한 회수율은 95% 이상으로 높았다.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.06a
• /
• pp.5-8
• /
• 2006

수소 station에서 수소분리정제를 위한 compact형 PSA 공정 설계를 위하여 활성탄으로 충진된 dual bed의 흡착동특성을 연구하였다. 기존 PSA 공정의 흡착탑이 차지하는 시스템의 공간을 줄이기 위하여 하나의 흡착탑 안에 다른 흡착탑을 넣어 흡착탑이 차지하는 공간을 최소화하고, 흡착탑 간의 열교환을 효과적으로 할 수 있도록 고안하였다. 수소 혼합물에 대한 dual bed에서의 흡착, 탈착 실험 실시하였으며, 시간에 따른 농도와 온도의 변화를 측정하였다. 수소 혼합물로는 $H_2/CO/CH_4/CO_2$ (69:2:3:26vol.%)를 사용하였으며, 흡착유량은 7LPM, 흡착압력은 9atm 조건에서 운전하였다. Inner bed와 outer bed의 수소 농도 파과곡선의 형태에 있어 차이를 보였으며, 이는 각 탑에서 열교환 효과로 인한 내부 온도 차이에 기인하여 발생하였다.

• Applied Chemistry for Engineering
• /
• v.29 no.1
• /
• pp.28-36
• /
• 2018

Adsorption experiments of three target gases such as acetone, benzene, and methyl mercaptan (MM) were carried in a continuous reactor using the activated carbon prepared from waste citrus peel. In a single gas system, the breakthrough time obtained from using the activated carbon (WCAC) prepared from waste citrus peel. In a single gas system, the breakthrough time obtained from the breakthrough curve decreased with increasing the inlet concentration and flow rate, but increased with respect to the aspect ratio (L/D). Adsorbed amounts of the target gases by WCAC increased as a function of the inlet concentration and aspect ratio. However, adsorbed amounts with the increase of the flow rate were different depending upon target gases. Results from the breakthrough time and adsorbed amount showed that the affinity for WCAC was the highest in benzene, followed by acetone and then MM. On the other hand, in the binary and ternary systems, the breakthrough curve showed a roll-up phenomenon where the adsorbate having a small affinity for WCAC was replaced with the adsorbate with a high affinity. The adsorption of acetone on WCAC was more strongly affected when mixing with the nonpolar benzene than that of using sulfur compound MM.

• Korean Chemical Engineering Research
• /
• v.43 no.3
• /
• pp.432-437
• /
• 2005

An electric swing adsorption (ESA) process for recovering highly pure $CO_2$ from the mixed gases was tested. In this study, activated carbon fibers were used as an adsorbent. The activated carbon fibers showed fast adsorption rate and the high adsorption capacity for $CO_2$ adsorption under the condition of the ambient pressure. Activated carbon fiber with higher specific surface area was suitable to repeated adsorption-desorption cycle process, showing consistent breakthrough curve. Especially, the regeneration method by vacuum combined with ESA improved the performance of desorption process by an additional 17％ regeneration efficiency compared to a vacuum only method, and showed the high regeneration efficiency at comparatively low 7-8 Wh energy.

• Clean Technology
• /
• v.7 no.4
• /
• pp.265-272
• /
• 2001

본 연구는 지구 온난화 현상의 주원인이 되는 $CO_2$ 를 화력발전소 연도가스로부터 분리 회수하기 위한 PSA 공정 개발용 기초자료를 습득하기 위하여 실시하였다. 연도가스와 유사한 조건하에서 국내에서 제조된 활성탄을 이용하여 이산화탄소 및 밸런스를 이루고 있는 질소 가스의 흡착평형 및 흡착속도 실험을 실시하였으며, 분석을 위하여 자체 제작한 장치(부피측정법) 및 TGA 장치를 각각 사용하였다. 이 연구에서 획득한 흡착등온선으로부터 사용된 흡착제가 이산화탄소의 분리에 적절한지 판단할 수 있었다. 또한, TGA에 의해 측정된 흡착속도 자료는 향후 사용될 흡착탑의 파과곡선 예측에 사용될 수 있다. 연구결과로부터 다음과 같은 사실을 알 수 있었다. 첫째, 낮은 흡착온도 일수록 흡착량이 많고 빠른 흡착속도를 나타내었다. 둘째, 압력이 높아질수록 흡착량은 증가하였다. 셋째, SGT활성탄이 SGA-100 및 SGP-100활성탄 보다 다소 많은 흡착량과 빠른 흡착속도를 보였다.

• Proceedings of the KAIS Fall Conference
• /
• 2005.05a
• /
• pp.315-317
• /
• 2005

공기중의 산소농축 PSA 기술로 RPSA(Rapid Pressure swing adsorption)이 적용되므로 1979년 이후 소형의 의료용 장치로 상업화되기 시작하였다. 산소발생기(산소농축기)의 경우에도 개량형 RPSA방식을 적용한 기술로써 최근 우리나라도 고령화 사회가 되므로써 의료용으로 사용이 확대되고 있으며, 기타 작업장이나 특수 시설 등에서 사용이 증대되고 있다. 이러한 산소농축기의 핵심부품 중의 하나인 흡착탑의 경우 흡착제 구성 및 흡착탑의 구조에 의하여 성능이 좌우되고 있다. 현재 상용화된 제올라이트의 각 흡착제의 흡착특성을 도출하기 위하여 압력, 온도, 수분함유량에 따른 파과곡선을 측정하여 흡착탑의 단수에 따른 최적 단수를 도출하였다.

• Clean Technology
• /
• v.18 no.3
• /
• pp.312-319
• /
• 2012

Malachite green is used a dye but malachite green is harmful toxic substance. In this study, the adsorption characteristics of zeolite has been investigated for the adsorption of malachite green dissolved in water. The effects of initial dye concentration, contact time, pH and temperature on adsorption of malachite green by a fixed amount of zeolite have been studied in batch adsorber and fixed bed. The adsorption equilibrium data are successfully fitted to the Freundlich isotherm equation in the temperature range from 25 to $45^{\circ}C$. The estimated values of k and ${\beta}$ are 23.60-46.88, 0.225-0.347, respectively. The mechanism of the adsorption process was determined from the intraparticle diffusion model. The effects of the operation conditions of the fixed bed on the breakthrough curve were investigated. When the inlet concentration and initial flow rate of malachite green are increased, the corresponding adsorption breaktime appears to decrease. Breaktime increased with increasing bed height and length of adsorption zone showed similar patterns.

• Journal of Soil and Groundwater Environment
• /
• v.12 no.5
• /
• pp.33-36
• /
• 2007

In recent years the convective-dispersive equation has been often discredited in predicting subsurface solute transport under field conditions due to presence of preferential flow paths. Kim et al. (2005) proposed a simple equation that can predict the breakthrough of solutes without excessive data requirements. In their Generalized Preferential Flow Model (GPFM), the soil is conceptually divided in a saturated "distribution layer" near the surface and a "conveyance zone" with preferential flow paths below. In this study, we test the model with previously published data, and compare it with a classical convective-dispersive model (CDM). With three parameters required-apparent water content of the distribution zone, and solute velocity and dispersion in the conveyance zone-GPFM was able to describe the breakthrough of solutes both through silty and sandy loam soils. Although both GPFM and CDM fitted the data well in visual, variables for GPFM were more realistic. The most sensitive parameter was the apparent water content, indicating that it is the determining factor to apply GPFM to various soil types, while Kim et al. (2005) reported that changing the velocity of GPFM reproduced solute transport when same soils were used. Overall, it seems that the GPFM has a great potential to predict solute leaching under field conditions with a wide range of generality.

• Korean Chemical Engineering Research
• /
• v.40 no.6
• /
• pp.694-702
• /
• 2002

Activated carbons have been used as adsorbents in various industrial application, such as solvent recovery, gas separation, deodorization, and catalysts. In this study, the effects of residual water on the activated carbon adsorbent surface on the adsorption capacity of $CCl_4$ were investigated. Adsorption behavior in a fixed bed was studied in terms of feed concentration, flow rate, breakthrough curve and adsorption capacity for $CCl_4$. Desorption characteristics of residual water on activated carbon were also studied. The water contents of the activated carbon were varied in the range of 0-20%(w/w) and all experiments were performed at 298.15 K. The adsorption equilibrium data $CCl_4$ on the activated carbon were well expressed by Langmuir isotherm. The adsorption capacity of $CCl_4$ decreased with increasing residual water content. Desorption of residual water in activated carbon decreased expotentially with $CCl_4$ adsorption. The obtained breakthrough curves using LDF(linear driving force) model represented our experimental data.