• Journal of Korean Society for Atmospheric Environment
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• v.21 no.2
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• pp.155-160
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• 2005

Removal of methyl mercaptan was investigated using adsorption on virgin activated carbon (VAC) and modified activated carbons with acidic chemicals in the present work. CAC, NAC, AAC and SAC were represented as activated carbons modified with HCI, HNO$_{3}$, CH$_{3}$COOH and H$_{2}$S0$_{4}$ ,respectively The pore structures were evaluated using nitrogen isotherm. The surface properties of virgin activated carbon and modified activated carbons were characterized by EA, pH of carbon surface and acid value from Boehm titration. The modification of activated carbon with acidic chemicals resulted in a decrease in BET surface area, micropore volume and surface pH, but an increase in acid value. The order of the adsorption capacity of activated carbons was NAC>AAC>SAC>CAC>VAC, and in agreement with that of acid value of activated carbons, whereas in disagreement with that of micropore volume of activated carbons. It appeared that chemical adsorption played an important role in methyl mercaptan on modified activated carbons with acidic chemicals compared to virgin activated carbon. Modifying activated carbon with acidic chemicals enabled to significantly enhance removal of methyl mercaptan.

• Journal of Environmental Science International
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• v.17 no.5
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• pp.493-500
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• 2008

This paper describes the adsorption/desorpton efficiency of a modified activated carbon by irradiated microwave to treat toluene. By employing microwave energy, the regeneration time was considerably shortened compared with conventional thermal heating regeneration. New adsorbent called ACB (Activated Carbon-Bentonite) was prepared from powder activated carbon with mixing bentonite as a binder. Specific surface area, average pore size and total pore volume of ACB were calculated from the nitrogen adsorption/desorption isotherm. The surface of ACB was characterized with scanning electron microscope(SEM). The results showed that the specific surface area, total pore volume, average pore size of ABC was not influenced by regenerating cycle with microwave irradiation. Toluene was adsorbed onto ACB which desorbed by MW irradiation. Absorption capacity of ACB was 0.117 $g_{toluene}/g_{ACB}$. Desorption efficiency of toluene increased as higher microwave output was applied.

• Journal of the Korean Institute of Gas
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• v.19 no.2
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• pp.37-44
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• 2015

We proposed the improved Langmuir adsorption relations considering volume change effect of coal matrix during primary production of CBM and Enhanced-CBM with injection of carbon dioxide or CCS in coalseam but also volumetric strain. To verify this model, experimental data of pure gas adsorption such as $CO_2$, $CH_4$, and $N_2$ on coals were used to compare conventional Langmuir model with this model. From the results, we obtained that the larger adsorption capacity of coal and the higher adsorption affinity of gas, the larger error occur with Langmuir model. Using this model, however, we found not only substantially better fit in all condition but also reasonable volumetric strain of the coal matrix. We also applied this volume modified pure gas adsorption model to the IAS model to describe gas adsorption and volumetric strain for mixed gas. This modified-IAS model fitting experimental data by Hall et al(1994) improved accuracy of mixed gas adsorption calculation compared with conventional model.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.73-76
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• 2007

In this study, methane gas adsorption ability of activated carbon (AC) with surface functional group effect, adsorbed methane amount was evaluated after nitric acid and ureatreatment of AC surface. Specific surface area and pore distribution of AC were studied though nitrogen adsorption isotherm at 77 K. Micro pore volume was calculated through H-K method. Adsorbed methane amount was evaluated through volume method at room temperature by using auto adsorption apparatus. Adsorbed methane amount of AC was found to increase with to specific surface area increase.Correlation proposed between the methane adsorption amount and surface nature indicates that the surface nature plays an important role on the adsorption amount at a given temperature.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.2
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• pp.193-200
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• 2014

Objectives: To develop domestic charcoal tubes with good adsorption capacity, breakthrough experiments were performed on four types of activated charcoal. Materials: The adsorption capacity and the adsorption rate were determined using a modified Wheeler equation after the breakthrough experiment. For four types of charcoal (J, K, S and SKC Inc. 226-01), 100 mg were used in the breakthrough experiment. The test was done on benzene, toluene, n-hexane, and acetone in a dynamic chamber. Results: K charcoal had the greatest surface area and the highest micropore volume. J charcoal had a similar surface area and micropore volume to SKC charcoal. S charcoal had the lowest surface area and micropore volume. J charcoal had the highest adsorption capacity at 101, 252 and 609 ppm of benzene. The gap in benzene adsorption capacity among the types of charcoal was the least at 609 ppm and the greatest at 101 ppm. J charcoal showed the highest adsorption capacity at 54, 106, 228 and 508 ppm of toluene. J charcoal and SKC charcoal had a similar adsorption capacity for acetone. J charcoal had the highest adsorption capacity for n-hexane. In the experiment featuring 10% breakthrough volume, 10% breakthrough occurred at 18 liters at $2065.9mg/m^3$ for J charcoal and at 20 liters at $1771.2mg/m^3$ for K charcoal. It was difficult to judge adsorption capacity by surface area and micropore volume of charcoal. J charcoal, which was similar to SKC charcoal in surface area and micropore volume, showed good adsorption capacity at common workplace concentrations. Conclusions: The adsorption capacity of J and K charcoal was superior compared with SKC charcoal. J and K charcoal can be considered appropriate for use as sampling media based on this result.

• Carbon letters
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• v.14 no.1
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• pp.27-33
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• 2013

An increase in population initiating rapid industrialization was found to consequently increase the effluents and domestic wastewater into the aquatic ecosystem. In this research the potentialities of Sambucus nigra L. (SNL) plant in the remediation of water, contaminated with methylene blue (MB), a basic dye were investigated. SNL was chemically impregnated with $KHCO_3$. Operating variables studied were pH, amount of adsorbent and contact time. In general, pH did not have any significant effect on colour removal and the highest adsorption capacity was obtained in 0.035 g MB/g-activated carbon. The Langmuir, Freundlich, Temkin and Dubinin-Radushkevich adsorption models were applied to describe the equilibrium isotherms. The adsorption isotherm data were fitted to the Temkin isotherm. The mass transfer property of the sorption process was studied using Lagergren pseudo-first-order and chemisorption pseudo-second-order kinetic models. The sorption process obeyed the pseudo-second-order kinetic model. The surface area, pores volume and diameter were assessed by the Brunauer-Emmett-Teller and Barrett-Joyner-Halenda methods. The results were compared to those from activated carbon (Merck) and an actual sample. The results indicate that SNL can be employed as a natural and eco-friendly adsorbent material for the removal of dye MB from aqueous solutions.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.624-634
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• 2020

The ability of natural and modified clay to adsorb phenol was studied. The clay samples were analyzed by different technical instruments, such as X-ray fluorescence (XRF), X-ray diffraction (XRD) and FT-IR spectroscopy. Surface area, pore volume and average pore diameter were also determined using B.E.T method. Up to 73 and 99% of phenol was successfully adsorbed by natural and activated clay, respectively, from the aqueous solution. The experiments carried out show that the time required to reach the equilibrium of phenol adsorption on all the samples is very close to 60 min. The amount of phenol adsorbed shows a declining trend with higher pH as well as with lower pH, with most extreme elimination of phenol at pH 4. The adsorption of phenol increases proportionally with the initial phenol concentration. The maximum adsorption capacity at 25 ℃ and pH 4 was 29.661 mg/g for modified clay (NaMt). However, the effect of temperature on phenol adsorption was not significant. The simple modification causes the formation of smaller pores in the solid particles, resulting in a higher surface area of NaMt. The equilibrium results in aqueous systems were well fitted by the Freundlich isotherm equation (R² > 0.98). Kinetic studies showed that the adsorption process is best described by the pseudo-second-order kinetics (R² > 0.99). The adsorption of phenol on natural and modified clay was spontaneous and exothermal.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.77-85
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• 2012

The present study investigates treatment methods for removal of arsenic from wastewater. The granular activated carbon (GAC) with the coating of iron chloride ($FeCl_3$) was used for the treatment of a low concentration of arsenic from wastewater. Batch experiments were performed to investigate the synthesis of Fe-GAC (Iron coated granular activated carbon), effects of pH, adsorption kinetics and the Langmuir model. The synthesized Fe-GAC with 0.1 M $FeCl_3$ shows best removal efficiency. Adsorption studies were carried out in the optimum pH range of 4-6 for arsenic removal. The Fe-GAC showed promising results by removing 99.4% of arsenic. In the adsorption isotherm studies, the observed data fitted well with the Langmuir models. In continuous column study showed that As(V) could be removed to below 0.25 mg/L within 1,020 pore volume. Our results suggest that the surface modified granular activated carbon treated with $FeCl_3$ for effective removal of arsenic from wastewater.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.6
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• pp.425-435
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• 2020

Numerous chemical modifications on activated carbon such as acidic conditioning, thermal treatment and metal impregnation have been investigated to enhance adsorption capacities of micropollutants in water treatment plants. In this study, chemical modification including acidic, alkaline treatment, and iron-impregnation was evaluated for adsorption of 2,4-dichlorophenol (2,4-DCP). For Fe-impregnation, three concentrations of ferric chloride solutions, i.e., 0.2 M, 0.4 M, and 0.8 M, were used and ion-exchange (MIX) of iron and subsequent thermal treatment (MTH) were also applied. Surface properties of the modified carbons were analyzed by active surface area, pore volume, three-dimensional images, and chemical characteristics. The acidic and alkaline treatment changed the pore structures but yielded little improvement of adsorption capacities. As Fe concentrations were increased during impregnation, the active adsorption areas were decreased and the compositional ratios of Fe were increased. Adsorption capacities of modified ACs were evaluated using Langmuir isotherm. The MIX modification was not efficient to enhance 2,4-DCP adsorption and the MES treatment showed increases in adsorption capacities of 2,4-DCP, compared to the original activated carbon. These results implied a possibility of chemical impregnation modification for improvement of adsorption of 2,4-DCP, if a proper modification procedure is sought.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.305-311
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• 2021

Effects of chitosan as a mesopore directing agent of SAPO-34 catalysts were investigated to improve the catalytic lifetime in DTO reaction. The synthesized catalysts were characterized by XRD, SEM, N₂ adsorption-desorption isotherm and NH₃-temperature programmed desorption (TPD). The modified SAPO-34 catalysts prepared by varying the added amount of chitosan showed the same cubic morphology and chabazite structure as the conventional SAPO-34 catalyst. As the added amount of chitosan increased to 3 wt%, the surface area, mesopore volume and concentration of weak acid sites of modified SAPO-34 catalysts increased. The modified SAPO-34 catalysts showed enhanced catalytic lifetime and high selectivity for light olefins in the DTO reaction. In particular, the SAPO-CHI 3 catalyst (3 wt%) exhibited the longest catalytic lifetime than that of the conventional SAPO-34. Therefore, it was confirmed that chitosan was a suitable material as a mesopore directing agent to delay deactivation of the SAPO-34 catalyst.