• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.784-790
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• 2010

VOCs such as acetone, benzene, toluene, ethylbenzene were adsorbed in a fixed-bed adsorber using zeolite synthesized from coal fly ash and 4 kinds of activated carbon at 101.3 kPa. The adsorber was operated batchwise with the charge of 5 g adsorbent to obtain the breakthrough curve of VOCs. Experiments were carried out at $40^{\circ}C$, nitrogen flow rate of $70cm^3/min$ and sparger temperature of $30^{\circ}C$. The deactivation model was tested for these curves by combining the adsorption of VOCs and the deactivation of adsorbent particles. The observed values of the adsorption rate constant and the deactivation rate constant were evaluated through analysis of the experimental breakthrough data using a nonlinear least square technique. The experimental breakthrough data were fitted very well to the deactivation model than the adsorption isotherm models in the literature. Also, adsorption capacities of adsorbents were obtained from the breakthrough curve to observe the correlation between adsorption capacity and the physical properties of VOCs.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.5
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• pp.17-23
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• 2013

Six-valent chromium ($Cr^{6+}$) is a highly toxic pollutant, supplied in a variety of industrial activities such as leather tanning, cooling tower blowdown, and plating. Herein, we investigated the removal of $Cr^{6+}$ from aqueous phase using low-cost adsorbents. Steel slag, montmorillonite, illite, kaolinite, red mud, and acid treated red mud with 0.5, 1.0, and 2.0 M HCl were used as adsorbent for the removal of $Cr^{6+}$ and the results showed that acid treated red mud with 2.0 M HCl (ATRM-2.0 M) had higher adsorption capacity of $Cr^{6+}$ than other adsorbents used. Accordingly, $Cr^{6+}$ removal by ATRM-2.0 M were studied in a batch system with respect to changes in initial concentration of $Cr^{6+}$, initial solution pH, adsorbent dose, adsorbent mixture, and seawater. Equilibrium sorption data were described well by Freundlich isotherm model. The influence of initial solution pH on $Cr^{6+}$ adsorption was insignificant. The use of the ATRM-2.0 M alone was more effective than mixing it with other adsorbents including red mud, zeolite, oyster shell, lime stone, and montmorillonite for the removal of $Cr^{6+}$. The $Cr^{6+}$ removal of the ATRM-2.0 M was slightly less in seawater than deionized water, resulting from the presence of anions in seawater competing for the favorable adsorption site on the surface of ATRM-2.0 M. It was concluded that the ATRM-2.0 M can be used as a potential adsorbent for the removal of $Cr^{6+}$ from the aqueous solutions.

• Environmental Engineering Research
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• v.25 no.1
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• pp.96-103
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• 2020

The aim of this study is to investigate the effect of five different combinations including: sand 70%, bentonite 30% (S₇₀B₃₀)- sand 80%, bentonite 20% (S₈₀B₂₀)- sand 80%, organophilic 20% (S₈₀M₂₀)- sand 60%, bentonite 20%, organophilic 20% (S₆₀B₃₀M₂₀) and sand 75% - bentonite 15% - organophilic 10% (S₇₅B₁₅M₁₀) on landfill linear structure in order to decrease phenol leaching. Hydraulic conductivity and adsorption behavior of the samples were investigated. The results demonstrated that the lowest hydraulic conductivity coefficient ($1.16{\times}10^{-11}{\frac{m}{s}}$) was obtained for S₇₀B₃₀. Furthermore, adding more than 20% of bentonite had no significant effect on reducing permeability. Moreover, Freundlich isotherm was introduced as the best model explaining adsorption behaviour due to its highest determination coefficient (0.945). The best samples for adsorption capacity of phenol and for both permeability and adsorption are S₈₀M₂₀ and S₆₀B₃₀M₂₀, respectively. Although the presence of bentonite was effective in reducing hydraulic conductivity, organic clay had no considerable impact on reducing permeability. Though, it's an exceptional role in adsorbing organic contaminants including phenol cannot be ignored. To meet all regulatory constraints, the optimal compound is made up of 10.2% of bentonite and 2.8% of organophilic clays with a minimized cost of 13.64 ($/ton).

• Journal of the Korean Chemical Society
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• v.54 no.3
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• pp.300-309
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• 2010

The ability of sodium-exchanged clay particles as an adsorbent for the removal of commercial dyes, Methylene blue (MB) and Malachite green oxalate (MG) from aqueous solutions has been investigated under various experimental conditions. The effect of the experimental parameters, such as pH solution, agitation time, adsorbate concentration and adsorbent dose were examined. Maximum adsorption of dyes, i.e. >90% has been achieved in aqueous solutions using 0.03 g of clay at a pH of 7 and 298 K for both dyes. The adsorption process was a fast and the equilibrium was obtained within the first 5 min. For the adsorption of both MB and MG dyes, the pseudo-second-order reaction kinetics provides the best correlation of the experimental data. The adsorption equilibrium results follow Langmuir and Dubini-Radushkevich (D-R) isotherms with high regression coefficients $R^2$ > 0.98. The mean free energies $E_a$ of adsorption from D-R model were 3.779 and 2.564 kj/mol for MB and MG respectively, which corresponds to a physisorption process.

• Journal of the Korea Organic Resources Recycling Association
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• v.7 no.1
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• pp.13-21
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• 1999

The purposes of this research were to evaluate the character of laboratory wastewater, and to examine the utilization of waste egg shells for neutralization and removal of heavy metals. Waste egg shells are excellent at neutralizing acidic wastewater, because they have alkaline minerals such as calcium. It must be seemed that removal rate of heavy metals were very influenced by adsobent dosage and adsorbate concentrations, because waste egg shells acted as precipitation and adsorption. If we reflected the adsorption capacity(k) and adsorption(1/n) of Freundlich isotherm, we couldn't consider waste egg shells as a good adsorbent. In view of these results, it showed that wastes containing the similar compositions as waste egg shells could utilize the neutralization, precipitation and adsorption of heavy metals in laboratory wastewater.

• Resources Recycling
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• v.20 no.6
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• pp.28-36
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• 2011

The adsorption of nickel(Ni) from sulfuric acid solution was carried out by ion exchange method. A series of batch tests in synthetic solutions were carried out using Lewatit Monoplus TP 220 resin. The following experimental parameters, such as temperature, shaking rate, reaction time, pH, resin dosage and concentration of nickel ions etc. were investigated to establish the effective optimum conditions of nickel adsorption. The solution pH(2.0~5.0) and shaking rate had little effects on the adsorption of nickel and adsorption time of 72hours was required to reach equilibrium. The experimental results show a good agreement with Feundlich isotherm and pseudo-second order reaction. The adsorption behavior of Ni obtained from synthetic solution was compared with that of waste electroplating solution. Elution of nickel from loaded resin increased with increase in $H_2SO_4$ concentration.

• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.46-55
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• 1999

This study compared the adsorption characteristics of heavy metal ions by crab shell, treated crab shell with 2N-HCl, treated crab shell with 4%-NaOH, chitin and chitosan.Using crushed crab shell, the heavy metal ions removal rates of $Cd^{2+}$ and $Zn^{2+}$ were about 70-80% in 45minutes, but the removal rates of $Cu^{2+}$, $Cr^{6+}$ and $Pb^{2+}$ was less than 10%, 10% and 30%, respectively. For the by-products crab shell by 2N-HCl treatment, it was shown that the removal rates of $Cu^{2+}$ and $Pb^{2+}$ were about 70-80% in 45minutes reaction. But, some problems were observed, that the contained protein in crab shell was changed into gel in the mixing solution after a few hours. For the by-products of crab shell by 4%-NaOH treatment, the removal rates of Pb and Zn were about 90% in 45 minutes, and those of capacity of chitin and chitosan powder was better than those of the other by-products. The more adding to the adsorbent dosages increased the removal rates, and the adsorption reaction was rapidly occurred in a few minute. Using 1.0 wt% chitin powder, the heavy metal removal rates were ordered $Cu^{2+}$(94%) > $Zn^{2+}$(89%) > $Cd^{2+}$(88%) > $Pb^{2+}$(77%) > $Cr^{6+}$(58%) in 45 minutes. Using 1.0 wt% chitosan powder, the heavy metal removal rates were ordered $Cu^{2+}$(99%) > $Pb^{2+}$(96%) > $Cd^{2+}$(79%) > $Zn^{2+}$(71%) > $Cr${6+}$(46%) in 45minutes. The degree of degree of deacetylation by prepared chitosan was 91%.The Freundlich adsorption isotherm of $Cu^{2+}$, $Cd^{2+}$ and $Zn^{2+}$, when it was applied to 1.0 wt% chitosan powder in minutes, can be acceptable very strictly. The equation constant (1/n) for $Cu^{2+}$, $Cd^{2+}$ and $Zn^{2+}$ were 0.54 0.41 and 0.23 respectively.

• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.265-269
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• 2016

Ammonia gas as a hydrogen source has received great attention since the importance of hydrogen gas as a clean energy source increased. However, ammonia is toxic and corrosive to metal such that the absorbent that can store and transport ammonia became an important issue. As an effort to solve this, a large pored covalent organic framework, COF-10 was proposed as an adsorbent for storage and safe transportation of ammonia. During the ammonia adsorption process, boron in COF-10 structure can act as a Lewis acid site and bind with ammonia. In this study, COF was synthesized and its structure was identified by BET, XRD and FT-IR. The adsorption characteristics of COF were investigated by TPD and adsorption isotherm. The COF-10 showed an excellent adsorption capacity for ammonia (9.79 mmol/g) which could be utilized as an ammonia adsorbent.

• Nuclear Engineering and Technology
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• v.28 no.1
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• pp.44-55
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• 1996

For the purpose of controlling the release of radioiodine to the environment in nuclear power plants, adsorption characteristics of elemental iodine and methyl iodide on the base carbon and 2%, 5% TEDA impregnated carbons were studied. The amounts of adsorption of elemental iodine and methyl iodide on the carbons were compared with Langmuir, Freundlich, Sips and Dubinin-Astakhov(DA) isotherm equations. Adsorption data were well correlated by the DA equation based on the potential theory. Adsorption energy distributions were obtained from the parameters of the DA equation derived from the condensation approach method. For the adsorption of methyl iodide and elemental iodine-carbon system, the DA equation can be well expressed by the degree of heterogeneity of the micropore system because the surface is nonuniform when its potential energy is unequal. The adsorption energy distribution wes investigated to find a surface heterogeneity on the carbon. The surface heterogeneity for iodine-carbon system is highly affected by the adsorbate-adsorbent interaction as well as the pore structure. The surface heterogeneity increases as a content of TEDA impregnated increases. The adsorption nature of methyl iodide on carbon turned out to be more heterogeneous than that of elemental iodine.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.413-416
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• 2008

Recently, the results of vital tissue test showed that nitrosodimethylamine (NDMA) as a disinfection by-product (DBP), could be regarded as a carcinogen because a tumor was observed in organs. U.S.EPA indicated 0.7 ng/L as exposure concentration of NDMA based on a risk assessment target with a lifetime cancer risk of $10^{-6}$. Several recent studies have shown that UV oxidation could remove NDMA. However, UV oxidation is uneconomical and can reform NDMA after treating. In addition, the treatment mechanism of adsorption has not been founddue to the uncertainty of NDMA pathway. In addtion, NDMA has a radioisotope $^{14}C$-labeled which can be analyzed at low concentration of NDMA by Liquid Scintillation Counter (LSC). This study has investigated NDMA determination using LSC at an extremely low range from 1 to 100 ng/L and NDMA removal by powdered activated carbon (PAC) adsorption. For $^{14}C$-NDMA by LSC, the highest correlation over 99% between count number and NDMA concentrationwas obtained with possibility of $^{14}C$-NDMA concentration up to 1 ng/L. In the presence of PAC ranging from 50 to 10,000 mg/L, $^{14}C$-NDMA was removed from 18% to 97% for Sigma-Aldrich corporation (S-A co.) and from 9% to 93% by PAC for Daejung corporation (Dj co.). Hence it was found that the removal efficiency by PAC adsorption could vary depending on PAC types from different companies. For PAC adsorption capacity of $^{14}C$-NDMA using the Freundlich isotherm, $K_f$ and 1/n of PAC from S-A co. were $2.67\times10^{-3}$ ng/mg and 1.009, while those of PAC from Dj co. were $1.30\times10^{-3}$ ng/mg and 0.994, respectively. Thus, PAC from S-A co. showed twice higher adsorption capacity than Dj co.