• 한국농공학회지
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• 제40권4호
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• pp.77-84
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• 1998

Adsorption and leaching characteristics of the artificial soils produced from water and wastewater treatment sludges were examined. The batch adsorption test and TCLP leaching test were used, and constituents of interest were heavy metals and nutrients. As, Cr, Cu, Pb, and Cd were analyzed for metals, and nitrogen and phosphorus were analyzed for nutrients. All the artificial soils showed strong adsorption and low leaching for the heavy metals, which implies that the artificial soils may not be hazardous to the environment due to heavy metals and even they can be utilized effectively to remove metals in solution like mine and industrial wastewaters. This is quite promising result because in most case heavy metals are the most concern in the application of sludge product to the farmland. For the nutrients, generally, artificial soils showed high adsorption and low leaching except artificial soil from wastewater sludge produced by low temperature firing. The artificial soils produced from water treatment sludge were active in adsorbing nutrients and showed low leaching that they can be practically used to remove nutrients in advanced treatment process of the wastewater. The artificial soils produced from wastewater treatment sludge were less active in adsorbing nutrients and showed high teaching. However, they could be used usefully if applied properly to the plant growing because of their fertilizing effect. Based on the test results, overall, the artificial soils were thought to be not hazardous to the environment and they could be more useful if applied properly.

• Carbon letters
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• 제2권1호
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• pp.44-54
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• 2001

The characteristics of adsorption and desorption of benzene and toluene were investigated at a fixed bed packed with the activated carbon and activated carbon fiber. Through breakthrough experiments under various feed concentration conditions, it was found that the slope of mass transfer zone and the tailing in the breakthrough curves were different from the feed conditions due to different heats of adsorption. In hot nitrogen desorption, the regeneration time and mass transfer zone of the toluene desorption curve were longer than those of the benzene desorption curve because of the difference in adsorption affinity. With an increase in the regeneration temperature, the height of roll-up and the sharpness of desorption curves increased but the regeneration times decreased. The adsorption capacities of the activated carbon and activated carbon fiber after three-time thermal regenerations decreased about 25% and 37% for benzene and 18% and 25% for toluene, respectively. To investigate the effect of the regeneration temperature on the energetic efficiency, the characteristic desorption temperatures of toluene and benzene were investigated by calculating purge gas consumption and temperature.

• Carbon letters
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• 제8권4호
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• pp.299-306
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• 2007

Four stream- activated carbons were prepared by carbonizing apricot stones at $600^{\circ}C$ followed by gasification with steam at $950^{\circ}C$ to burn-off's=17, 32, 49 and 65%. The textural parameters of these activated carbons were determined from nitrogen adsorption results at 77 K. The total pore volume and the mean pore radius increased with the increase of % burn-off whereas the surface area increased with the increase of burn- off from 17 to 32 and further to 49%. Further increase of burn-off to 65% was associated with a considerable decrease in surface area as a result of pronounced pore widening due to pore erosion. The surface pH values of the carbons investigated range between 7.1 and 8.2. The adsorption of oxamyl onto the activated carbon followed pseudo-second order kinetics and the equilibrium adsorption isotherms fitted Langmuir adsorption model. The adsorption of oxamyl proved to be of the physical type and took place in non-micropores. The amount of oxamyl adsorbed expressed as $q_m$ depends to a large extent to the surface area located in non-micropores $S^{\propto}\;_n$, where a straight line relationship passing through the origin was obtained.

• 한국대기환경학회지
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• 제33권1호
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• pp.1-10
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• 2017

Adsorption is a plausible technology using solid adsorbents for dry capture of carbon dioxide ($CO_2$). In general, narrow size distribution of tiny pores and surface chemical functionalities of solid adsorbents enhance the adsorption capacity of gaseous $CO_2$ molecules. In order to utilize the advantages of fibrous adsorbents, this work prepared activated carbon nanofibers (ACNFs) via the electrospinning process using a polymer precursor of polyacylonitrile (PAN). The spun fibers were 390 nm to 580 nm in thickness with an average surface area of $27.3m^2/g$. The surface structure was improved by a programmed thermal activation at $800^{\circ}C$ in $CO_2$ atmosphere. It was also found that the nitrogen-groups including pyrrole and pyridine were created during the activation facilitaing the selective adsorption as forming enhanced active sites. The finally obtained adsorption capacities were 2.74 mmol/g for pure $CO_2$ flow and 0.74mmol/g for 3000 ppm.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.569-573
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• 2013

In this study, activated carbon fabric was prepared from a cellulose-based polymer (viscose rayon) via a combination of physical and chemical activation (mixed activation) processes by means of $CO_2$ as a gasifying agent and surface and adsorption properties were evaluated. Experiments were performed to investigate the consequence of activation temperature (750, 800, 850 and $925^{\circ}C$), activation time (15, 30, 45 and 60 minutes) and $CO_2$ flow rate (100, 200, 300 and 400 mL/min) on the surface and adsorption properties of ACF. The nitrogen adsorption isotherm at 77 K was measured and used for the determination of surface area, total pore volume, micropore volume, mesopore volume and pore size distribution using BET, t-plot, DR, BJH and DFT methods, respectively. It was observed that BET surface area and TPV increase with rising activation temperature and time due to the formation of new pores and the alteration of micropores into mesopores. It was also found that activation temperature dominantly affects the surface properties of ACF. The adsorption of iodine and $CCl_4$ onto ACF was investigated and both were found to correlate with surface area.

• 대한화학회지
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• 제57권1호
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• pp.104-108
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• 2013

The adsorption characteristics of Cd(II) and Pb(II) in aqueous solution using granular activated carbon (GAC), activated carbon fiber (ACF), modified ACF (NaACF), and a mixture of GAC and NaACF (GAC/NaACF) have been studied. The surface properties, such as morphology, surface functional groups, and composition of various adsorbents were determined using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) measurements. The specific surface area, total pore volume, and pore size distribution were investigated using nitrogen adsorption, Brunauer-Emmett-Teller (BET), and Barrett-Joyner-Halenda (BJH) methods. In this study, NaACF showed a high adsorption capacity and rate for heavy metal ions due to the improvement of its ion-exchange capabilities by additional oxygen functional groups. Moreover, the GAC and NaACF mixture was used as an adsorbent to determine the adsorbent-adsorbate interaction in the presence of two competitive adsorbents.

• Carbon letters
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• 제9권1호
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• pp.8-16
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• 2008

Oxidized activated carbons were prepared by reacting steam-activated carbon developed from pecan shells with nitric acid of varying strength (15, 30, 45 and 60%). The textural properties and the chemistry of the surface of the non-oxidized and of the oxidized carbons were determined from nitrogen adsorption and base neutralization capacities. The uptake of Pb(II) and Cd(II) from aqueous solution by these carbons was determined by kinetic and equilibrium experiments as well as by the column method. Treatment with nitric acid brought about drastic decrease in surface area and remarkable increase in the pore size of the carbon with these changes depending on the strength of nitric acid. Nitric acid increased the surface acidity by developing new surface oxygen functional groups of acidic nature. $HNO_3$-oxidized carbons exhibited high adsorption capacities for Pb(II) and Cd(II). The adsorption of these ions increased with the decrease of the surface pH of the carbon and with the increase of the solution pH from 2.5 to 6 and 7. The amount adsorbed from lead and cadmium was also related to the amount of surface acidity, the pH of the point of zero charge and on some metal ion parameters. Cadmium and lead uptake by the investigated carbons followed pseudo-second order model and the equilibrium sorption data fitted Langmuir adsorption model.

• 한국습지학회지
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• 제21권2호
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• pp.152-156
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• 2019

본 연구는 수중 암모늄 이온을 처리하기 위하여 자성 제올라이트를 합성하여 흡착 특성을 평가하였다. 표면개질된 자성 제올라이트는 수열작용으로 합성되었다. 제올라이트와 $Fe_3O_4$ 복합체는 SEM과 XRD 분석 결과 혼합비 12.6% 범위이내에서 최적인 상태로 침투 혼합된 것으로 관찰되었다. 최적의 흡착 pH는 중성부근인 약 8근처에서 나타났고, 최대 흡착량은 $Fe_3O_4$ 함량의 증가에 따라 감소하였다. 수중 암모늄 이온은 Langmuir 식에 근사하는 흡착식으로 나타났다. 개발된 합성제올라이트 흡착제는 질소농도의 관리가 필요한 습지환경 보호에도 적용 가능할 것으로 판단된다.

• Korean Chemical Engineering Research
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• 제50권5호
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• pp.885-889
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• 2012

본 연구에서는 활성탄소의 이산화탄소 흡착 능력을 향상시키기 위한 아민과 금속산화물 첨가제에 관하여 고찰하였다. 표면 처리한 활성탄소의 물리화학적 특성은 X-ray photoelection specstroscopy (XPS), 질소등온흡착곡선, X-ray diffraction (XRD), BET 장치를 이용하여 분석하였다. 실험결과, 활성탄소 표면의 아민 기능기는 산성가스인 이산화탄소를 선택적으로 흡착하기 위한 염기성 자리로 작용하며, 2차아민을 갖는 기능기가 1차아민에 비하여 이산화탄소흡착능력이 우수함을 확인하였다. 활성탄소에 첨가된 금속산화물은 표면에서 전자 도우너(electron donor) 역할을 하며 알칼리 특성을 지니고, 아민 기능기와 유사하게 이산화탄소 가스와 산-염기 반응을 유도한다. 금속산화물 표면처리를 했을 경우 순수한 활성탄소와 비교하여 이산화탄소 흡착 용량이 85% 증가하였으며, 이러한 결과로 미루어 볼 때 금속산화물 첨가제는 활성탄소의 이산화탄소 흡착능력을 향상시키기 위한 목적으로 아민 첨가제와 병행하거나 대체할 수 있는 물질로 기대된다.

• 대한환경공학회지
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• 제33권8호
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• pp.606-616
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• 2011

본 연구는 흡착제의 흡착특성을 이해하는데 이용되는 각종 흡착모델의 적용성을 평가하는데 목적이 있다. 이를 위해 상용의 음이온교환수지(PA-308)를 이용하여 $NO_3^-$에 대한 흡착특성을 회분식 실험을 통해 조사하였다. 흡착등온과 흡착속도 실험결과는 일반적으로 널리 이용되고 있는 다양한 흡착등온식과 반응속도식을 통해 모델화하였다. 흡착평형실험은 흡착등온식을 적용하는데 있어 실험조건이 미치는 영향을 확인하기 위해 흡착제의 투여량을 일정한 값으로 고정하고 흡착질의 농도변화에 따른 조건과 흡착질의 농도를 일정한 값으로 고정하고 흡착제의 투여량 변화에 따른 조건으로 나누어 수행하였다. 흡착질의 농도를 변화시키는 조건에서의 흡착평형은 Langmuir와 Freundlich 흡착등온식을 결합한 형태의 Sips 흡착등온식과 Redlich-Perterson 흡착등온식에 의해 수식화가 가능하였다. 한편, 흡착제의 무게를 변화시키는 조건에서의 흡착평형은 단층 흡착, 균일표면을 가정하는 Langmuir 흡착등온식과 잘 일치하는 경향을 보였다. 이상의 결과는 $NO_3^-$에 대한 음이온교환수지의 흡착 메커니즘이 흡착실험 조건에 의해 달라질 수 있음을 시사한다.