• Environmental Engineering Research
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• v.11 no.1
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• pp.1-13
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• 2006

In this study, conventional biofilters packed with flexible synthetic polyurethane (PU) foam carriers were operated to remove toluene from a contaminated air stream. PU foams containing various adsorbents (e.g., zeolite, sepiolite, dolomite and barite) were synthesized for the biofilter media and their adsorption characteristics of toluene were determined. Adsorption capacity of PU-adsorbent foam was in the order of PU-dolomite ${\approx}$ PU-zeolite > PU-sepiolite > PU-barite. During the biofiltration experiment, influent toluene concentration was in the range of 0-160 ppm and EBRT (i.e., empty bed residence time) was 45 seconds. Pressure drop of the biofilter bed was 4-5 mm $H_2O/m$ column height. The maximum removal capacity was in the order of PU-dolomite > PU-zeolite > PU-sepiolite > PU-barite, while the complete removal capacity was in the order of PU-dolomite > PU-sepiolite > PU-zeolite > PU-barite. The better biofiltration performance in PU-dolomite foam was because PU-dolomite foam had lower density and higher porosity than the others providing favorable conditions for microbial growth. The results of biodegradation kinetic analysis showed that PU-dolomite foam had higher maximum removal rate ($V_m\;=\;11.04\;g$ toluene/kg dry material/day) and saturation constant ($K_s\;=\;26.57\;ppm$) than the other PU foams. This supports that PU-dolomite foam was better than the others for biofilteration of toluene.

• Environmental Engineering Research
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• v.15 no.4
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• pp.207-213
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• 2010

This study investigated the potential of using bottom ash to be used as an adsorbent for the removal of lead (Pb) from aqueous solutions. The physical and chemical characteristics of bottom ash were determined, with a series of leaching and adsorption experiments performed to evaluate the suitability of bottom ash as an adsorbent material. Trace elements were present, such as silicon and aluminum, indicating that the material had a good adsorption capacity. All heavy metals leached during the Korea standard leaching test (KSLT) passed the regulatory limits for safe disposal, while batch adsorption experiments showed that bottom ash was capable of adsorbing Pb (experimental $q_e$ = 0.05 mg/g), wherein the adsorption rate increased with decreasing particle size. The adsorption data were then fitted to kinetic models, including Lagergren first-order and Pseudo-second order, as well as the Elovich equation, and isotherm models, including the Langmuir, Freundlich and Dubinin-Radushkevich isotherms. The results showed that pseudo-second order kinetics was the most suitable model for describing the kinetic adsorption, while the Freundlich isotherm best represented the equilibrium sorption onto bottom ash. The maximum sorption capacity and energy of adsorption of bottom ash were 0.315 mg/g and 7.01 KJ/mol, respectively.

• Journal of environmental and Sanitary engineering
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• v.16 no.1
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• pp.72-90
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• 2001

This study was conducted to evaluate desorption efficiencies accuracy and precision by $CS_2$ and thermal desorption method for polar and non-polar organic solvents collected on activated carbon(AC), activated carbon fiber(ACF), carbosieve SIII, materials tested were Methyl alcohol, n-Hexane, Benzene, Trichloroethylene, Methyl isobutyl ketone and methyl cellosolve acetate and six different concentration levels of samples were made. The results were as follows ; 1. Accuracy on kind adsorbent and desorption method was low. In case of $CS_2$ desorption solvent, Overall B and Overall CV on AC and ACF were 43% and 6.63%, respectively. In case of thermal desorption method, accuracy of thermal desorption method appeared higher than solvent desorption method by AC 18.0%, 3.54%, ACF 2.6%, 2.57%, Carbosieve SIII 13.7% and 1.97%, respectively. 2. In the concentration level III, accuracy of thermal desorption method on adsorbent was in order as follow ; ACF > Carbosieve SIII > AC in the methyl alcohol and Carbosieve SIII > ACF > AC in the rest of them all subject material and Concentration levels showed good precision at EPA recommend standard (${\leq}{\;}30%$) 3. DEs by type of organic solvent adsorbent and desorption method are as follows ; In the case that desorption solvent is $CS_2$, DE of Methyl alcohol is AC 47.5%, DE of all materials is ACF about 50%. In the case of thermal desorption method, DE of Methyl alcohol is AC 82.0%, ACF 97.4%, Carbosieve SIII 86.3%. DE of the later case is prominently improved more than one of former. In particular, Except that DE of EGMEA is ACF 88.5%, DE of the rest of it is more than 95% which is recommend standard MDHS 72. With the result of this study, in order to measure various organic solvent occurring from the working environment, in the case of thermal desorption method, we can get the accurate exposure assessment, reduce the cost, and use ACF as thermal desorption sorbent which available with easy.

• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.548-552
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• 2010

This study focused on the development of effective adsorbent to remove acetylenes for the purification of isoprene. The adsorbents with various pore sizes from $4{\AA}$ to $5{\AA}$ were prepared to investigate the effect of pore size on selective adsorption of acetylene as an impurity. The pore size of zeolite A was adjusted by ion-exchange between Na and Ca ions. The pore size of adsorbents has affected the removal of acetylenes selectively because of the kinetic diameter of acetylenes, such as 2-methyl-1-butyne-3-yen (IPA) and 2-butyne. In a batch adsorption experiment, 5A zeolite with pore size of $5{\AA}$ showed the highest removal capacity of 2-butyne. However, IPA was hardly removed from isoprene by the A-type zeolites. For the adsorption isotherm, modified Langmuir model was well fitted with 2-butyne adsorption. Moreover, the regeneration of adsorbent was carried out to determine optimum method. The adsorbent heated for 12 h at $300^{\circ}C$ was regenerated significantly.

• Analytical Science and Technology
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• v.18 no.4
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• pp.309-319
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• 2005

The adsorption characteristics of gaseous molecules on the carbonaceous adsorbent have been investigated at various temperature and pressure with different pore sizes using Grand Canonical Monte Carlo (GCMC) simulation method. The geometrical parameters and spectroscopic properties of adsorbates have been computed using density functional theory (DFT). At higher temperatures is the adsorption amount of adsorbates is decreased due to their vaporization. Considering the pore size effect, the adsorption characteristic depends on the adsorbate size, polarity and interaction between adsorbates, etc. At all cases employed in this study, the adsorption amount of adsorbates on the carbonaceous adsorbent is increased in the order $NH_3$ < $H_2S$ < $CH_3SH$, and this result is qualitatively in good agreement with the experimental observation.

• Clean Technology
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• v.8 no.2
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• pp.61-66
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• 2002

Recycling method of red mud, byproduct from the aluminium manufacturing process, and paper sludge was investigated in order for them to be utilized as the adsorbent for the removal of volatile organic components(VOCs). Either high density polyethylene(HDPE) or low density polyethylene(LDPE) was added to facilitate the manufacture of adsorbents. The utilization of HDPE in the adsorbents increased the adsorption capacity due to the good physical properties, such as, BET and true density, compared with LDPE. BET values of the manufactured adsorbents were much lower than the commercial activated carbon ($10^{-2}-10^{-3}$). It may be due to the fact that the time for decomposition of the paper sludge was not enough during the manufacturing of adsorbents. But the specific adsorption capacity of the manufactured adsorbents (mole adsorbed per unit surface area) had much higher value than the commercial activated carbon (10-100). Therefore, it is important that BET of manufactured adsorbents needs to be increased to obtain the same adsorption capacity as the commercial activated carbon.

• Journal of Life Science
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• v.13 no.3
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• pp.365-373
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• 2003

Instead of deodorization appararus of fish oil, an adsorbent such as activated charcoal, activated alumina, silicagel, bamboo charcoal was packed in column alone or mixed with preparative ratio, and then test the effective deodorization with bleaching. In the progress of degumming, the effective method was 18 ml of 2.5% oxalic acid per 100m1 of crude large anchovy oil. The optical condition to deacidified was treating for 30 min at $40^{\circ}C$ with 2.5% sodium hydroride solution. The effective deodorization was added with 3% silicagel under the alone treating adsorbent, and mixed treating was 30% activated alumina and 10% silicagel but added to green tea powder was not effective. The major fatty acid of total lipid were 16:0, 20:5n-3, 18:1n-9, 16:1n-7 and 22:6n-3 after treatment of degumming, deacidfication and deodorizing in the large anchovy oil. The oxidative stability of refined anchovy oil added to $\alpha$-tocopherol was validated 20 days under the control, and 30 days in the case of $\alpha$-tocopherol. The 0.01% $\alpha$-tocopherol was more effective than 0.02% $\alpha$-tocopherol.

• Korean Chemical Engineering Research
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• v.51 no.3
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• pp.352-357
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• 2013

In this study, the pellet-type adsorbents were prepared by extrusion using water treatment sludge. Effects of binder and calcination on physical and chemical properties of pellet-type adsorbents were investigated. The porous structure and surface characteristics of the adsorbents were studied using nitrogen adsorption, compression strength, scanning electron microscope, X-ray diffraction, and infrared spectroscopy of adsorbed pyridine. With increasing of binder content to 5 wt%, the compressive strength of pellet-type adsorbent could be improved more than three times, but the surface area reduced by 30%, and thus the breakthrough time of trimethylamine was shortened. The breakthrough time of the trimethylamine, a basic gas, could be increased more than three times through calcination, which seems to be due to generation of acid sites composed of Lewis acid and Br$\ddot{o}$nsted acid sites on the adsorbent surface.

• Korean Journal of Environmental Agriculture
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• v.23 no.4
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• pp.240-244
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• 2004

The objective of this research was to develop the adsorbent far heavy metals by activating the bark sample. Barks from pine tree with diameters of $2{\sim}4\;mm$ were activated in the muffle furnace under a high relative humidity condition at temperatures of $600{\sim}900^{\circ}C$. The removal efficiency of the activated bark (ACTBARK) for Cu and Cd was temperature dependent showing the order of $900^{\circ}C$ > $800^{\circ}C$ > $700^{\circ}C$ > $600^{\circ}C$. The critical temperature was considered to be $900^{\circ}C$ to become an efficient adsorbent for Cu and Cd. The bark samples activated at temperatures lower than $700^{\circ}C$ showed a less removal efficiency than the crude bark. The ACTBARK activated at $900^{\circ}C$ removed more Cu and Cd from solution than the commercial activated carbon and charcoal. The ACTBARK (activated at $900^{\circ}C$) adsorbed all of the Cu and Cd in solution with concentrations less than 150 mg/L. The selectivity of the ACTBARK was in the order of Cu > Zn > Ni > Pb > Fe > Cd > Mn.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.148.2-148.2
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• 2013

We prepared hydrophobic PDMS-coated porous silica as pre-concentration adsorbent for chemical warfare agents (CWAs). Since CWAs can be harmful to human even with a small amount, detecting low-concentration CWAs has been attracting attention in defense development. Porous silica is one of the promising candidates for CWAs pre-concentration adsorbent since it is thermally stable and its surface area is sufficiently high. A drawback of silica is that adsorption of CWAs can be significantly reduced due to competitive adsorption with water molecule in air since silica is quite hydrophilic. In order to solve this problem, hydrophobic polydimethylsiloxane (PDMS) thin film was deposited on silica. Adsorption and desorption of chemical warfare agent (CWA) simulants (Dimethylmethylphosphonate, DMMP and Dipropylene Glycol Methyl Ether, DPGEM) on bare and PDMS-coated silica were studied using temperature programed desorption (TPD) with and without co-exposing of water vapor. Without exposure of water vapor, desorbed amount of DMMP from PDMS-coated silica was twice larger than that from bare silica. When the samples were exposed to DMMP and water vapor at the same time, no DMMP was desorbed from bare silica due to competitive adsorption with water. On the other hand, desorbed DMMP was detected from PDMS-coated silica with reduced amount compared to that from the sample without water vapor exposure. Adsorption and desorption of DPGME with and without water vapor exposing was also investigated. In case of bare silica, all the adsorbed DPGME was decomposed during the heating process whereas molecular DPGME was observed on PDMS-coated silica. In summary, we showed that hydrophobic PDMS-coating can enhance the adsorption selectivity toward DMMP under humid condition and PDMS-coating also can have positive effect on molecular desorption of DPGME. Therefore we propose PDMS-coated silica could be an adequate adsorbent for CWAs pre-concentration under practical condition.