• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.267-275
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• 1997

$ZrO_2$ Powder was Prepared by sol-gel process and the adsorption characteristic of cobalt($Co^{2+}$) by $ZrO_2$ adsorbent in high-temperature water was investigated using batch adsorption experiment with a stirred autoclave. The prepared $ZrO_2$ was calcined at $600{\sim}1400^{\circ}C$ and analyzed by X-ray diffractometry, SEM, BET surface area, FT-IR and TG-DTA measurement. The tetragonal Phase of $ZrO_2$ is produced $480^{\circ}C$ from amorphous gel at temperature $480^{\circ}C$. Both tetragonal and monoclinic phase of $ZrO_2$ exist at temperature between $600^{\circ}C$ and $1000^{\circ}C$. At temperature $1200^{\circ}C$, tetragonal to monoclinic phase trasition is occurred. The $Co^{2+}$ adsorption capacity of $ZrO_2$ calcined at $600^{\circ}C$ for 4 hours is 0.16 meq $Co^{2+}/g$ adsorbent in the high temperature at $250^{\circ}C$. The adsorption of $Co^{2+}$ on the $ZrO_2$ adsorbent is irreversible endothermic in the temperature range ($125-175^{\circ}C$). The standard enthalpy change (${\Delta}H^{\circ}$) of $ZrO_2$ calcined at $600^{\circ}C$ for 4 hours is 18 kJ/gmol.

• Journal of Appropriate Technology
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• v.7 no.1
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• pp.41-50
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• 2021

Gongali model Co. Ltd located in Arusha, Tanzania is operating a Nanofilter water station using locally produced bone char to remove fluoride in groundwater. Bone char produced locally had a high turbidity and high concentration of organic matter, which cause color. In addition, since the fluorine adsorption efficiency is low, there is a problem in high maintenance cost due to a short replacement cycle of bone char. In order to overcome this challenge, our research team was that a local furnace was manufactured and applied for produce high adsorption bone char in Gongali model Co. Ltd. By producing high-adsorption bone char locally, the operating efficiency of the Nanofilter water station increased, and it was possible to stably and continuously provide drinking water to local residents. In addition, by presenting a sustainable business model to Gongali model Co Ltd, the persistence of high adsorption bone char and a plan to spread the Nanofilter water station were suggested. Therefore, it was possible to propose a plan to continuously supply low-cost drinking water to the low-income and the neglected class through this local project.

• Journal of Korean Society on Water Environment
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• v.22 no.2
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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.

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

• Bulletin of the Korean Chemical Society
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• v.21 no.7
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• pp.705-708
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• 2000

Adsorption of CO and NO Moleculcs on a Pt(OO1)-hex R0.7° surface at 90 K is investigated by scanning tunneling microscopy (STM) in ultra-high vacuum environments. At an initial stage of adsorption, both molecules are preferentially adsorbed on th e Iess coordinated Pt atoms of the surface with hexagonal structure, which act as active sites. Domains of the adsorbates grow parallel to the stripe structure of the reconstructed surface because of Iower migration energy in this direction. The extra Pt atoms produced from adsorbate-induced restructuring give rise to anisotropic islands on the ( 1 x 1 ) surface. Each of the adsorbed NO molecules at low coveragcs is atomicalIy resolved during STM observation. However, the spots of the adsorbed CO are invisible.Such a behavior is probably explained in terms of different interactions between the adsorbates.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.132-139
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• 2018

A cost-effective preparation method is proposed to prepare nanoporous alumina (NA) using aluminum chloride as a precursor with a lower cost than aluminum butoxide. In addition, the surfactant template was replaced with magnesium stearate, which has a lower unit cost in stearate acid. The adsorption isotherm test for the CO gas was carried out to compare the adsorption performance of the NA adsorbents prepared using post-hydrolysis (NA) and cost-effective precipitation (C-NA). In addition, C-NA exhibited a similar uptake capacity as NA, and the maximum uptake capacity of Pd/C-NA increased 1.3 times via Pd nanodots loading.

• Journal of the Korean Ceramic Society
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• v.36 no.10
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• pp.1016-1021
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• 1999

In this study activated carbon fibers were prepared from PAN-based carbon fibers by physical activation with steam or carbon dioxide. The variations in specific surface area amount of iodine adsorption and pore size distribution of the activated carbon fibers after the activation process were discussed. in steam activation BET surface area of about 1019 m2/g was obtained after 77% burn-off while carbn dioxide activation produced ACF with 694m2/g of BET surface area after 52% burn-off. However carbon dioxide activation produced at a similar degree of activation higher micropore volume(0.37 cc/g) and amount of iodine adsorption (1589mg/g) than steam activation. Nitrogen adsorption isotherms for (PAN based activated carbon fibers that prepared by physical activation were of type I in the Brunauer-Deming-Deming-Teller classification

• Membrane and Water Treatment
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• v.11 no.3
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• pp.231-235
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• 2020

Industrialization and modern developments have led to an influx of toxic heavy metals into the aquatic environment, and the accumulation of heavy metals has serious adverse effects on humans. Among the various heavy metal treatment methods, adsorption is very useful and frequently used. Plastic materials, such as polypropylene and polyethylene, have been widely used as filter media due to their mechanical and chemical stability. However, the surface of plastic material is inert and therefore the adsorption capability of heavy metals is very limited. In this study, granular media and fiber media composed of polypropylene and polyethylene are used, and the surface modification was conducted in order to increase adsorption capability toward heavy metals. Oxygen plasma generated hydroxyl groups on the surface of the media to activate the surface, and then acrylic acid was synthesized on the surface. The grafted carboxyl group was confirmed by FT-IR and SEM. Heavy metal adsorption capability of pristine and surface modified adsorbents was also evaluated. Overall, heavy metal adsorption capability was increased by surface modification due to electrostatic interaction between the carboxyl groups and heavy metal ions. Fibrous PP/PE showed lower improvement compared to granular PP media because pore blockage occurred by the surface modification step, thereby inhibiting mass transfer.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.2
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• pp.18-25
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• 2003

The adsorption of co-cationic dual polymer system was investigated as was the fiber dispersion stability of a paper stock suspension. Polyaluminum chloride(PAC) and polyamidoamine epichlorohy-drin(PAE) polymers were used as wet-end additives. The adsorbed amounts of PAE polymer in a wet stock were measured by using polyelectrolytic PCD titration. The sheet forming experiments were carried out in a standard handsheet machine. Fiber dispersion stability and relative retention were evaluated in terms of M/K non-uniformity index and sheet basis weight, respectively. The PAE polymer adsorption of Langmuir-isothermal type decreased with increasing PAC addition level. The combination of the two cationic polymers presumably exerts a site-blocking effect by the low molecular weight PAC which gives a partial charge neutralization at a minimum level of addition. From a thermodynamic view point of PAE adsorption, an increase in adsorption entropy and a decrease in train number suggests that the PAR polymer has an extended conformation structure that potentially leads to an enhancement of the fiber dispersion stability. This conclusion is supported by handsheet experiments that examined the PAC-PAE dual polymer effects on the sheet formation and retention.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.268-268
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• 2012

Adsorption and desorption of toluene from bare and $TiO_2$-coated silica with a mean pore size of 15 nm was studied using breakthrough curves and temperature programmed desorption. Thicknesses of $TiO_2$ films prepared by atomic layer deposition on silica were < 2 nm, and ~ 5 nm, respectively. For toluene adsorption, both dry and humid conditions were used. $TiO_2$-thin film significantly improved toluene adsorption capacity of silica under dry condition, whereas desorption of toluene from the surface as a consequence of displacement by water vapor was more pronounced for $TiO_2$-coated samples with respect to the result of bare ones. In the TPD experiments, silica with a thinner $TiO_2$ film (thickness < 2 nm) showed the highest reactivity for toluene oxidation to $CO_2$ in the absence and presence of water. We show that the toluene adsorption and oxidation reactivity of silica can be controlled by varying thickness of $TiO_2$ thin films.