• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.373-379
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• 2009

Cesium carbonate was used as an adsorbent to capture carbon dioxide from gaseous stream of carbon dioxide, nitrogen, and moisture in a fixed-bed to obtain the breakthrough data of $CO_2$. The deactivation model in the non-catalytic heterogeneous reaction systems is used to analyze the sorption kinetics among carbon dioxide, carbonate, and moisture using the experimental breakthrough data. The experimental breakthrough data are fitted very well to the deactivation model than the adsorption isotherm models in the literature.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.250-255
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• 2004

The aim of this work was to investigate the adsorption isotherm and kinetic model for the biosorption of lead $(Pb^{2+})$ by Rhodotorula aurantiaca and to examine the environmental factors for this metal removal. Within five minutes of contact, $Pb^{2+}$ sorption reached nearly 86% of the total $Pb^{2+}$ sorption. The optimum initial pH value for removal of $Pb^{2+}$ was 5.0. The percentage sorption increased steeply with the biomass concentration up to 2 g/l and thereafter remained more or less constant. The Langmuir sorption model provided a good fit throughout the concentration range. The conformity of these data to the Langmuir model indicated that biosorption of $Pb^{2+}$ by R. aurantiaca could be characterized as a monolayer, single-site type phenomenon with no interaction between ions adsorbed in neighboring sites. The maximum $Pb^{2+}$ sorption capacity $(q_{max})$ and Langmuir constant (b) were 46.08 mg/g of biomass and 0.04 l/mg, respectively. The pseudo second-order equation was well fitted to the experimental data. The correlation coefficients for the linear plots of t/q against t for the second-order equation were 0.999 for all the initial concentrations of biosorbent for contact times of 180 min. The theoretical $q_{eq}$ value was very close to the experimental $q_{eq}$ value.

• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.737-741
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• 1997

The typical removal method of volatile organic compounds is adsorption process. In this study, granular activated carbon and activated carbon fiber were used as adsorbents, and the adsorption behavior for the two types of adsorbent was compared. And they were regenerated by supercritical carbon dioxide extraction at a constant temperature, 318.15 K, and 2000, 2500, 3000 psi respectively. The desorption percentage of initial adsorbates and iodine values were increased with pressure of supercritical carbon dioxide. The regeneration time was 70 and 60 minutes in adsorbents loaded with methyl ethyl ketone(MEK) and benzene, respectively. The desorption percentages were 64.0% for granular activated carbon and 55.3% for activated carbon fiber loaded with MEK, and 59.1% for granular activated carbon and 45.2% for activated carbon fiber loaded with benzene. The exit concentration could be evaluated by Tan and Liou model. Therefore, the granular activated carbon and the activated carbon fiber could be regenerated by supercritical fluid extraction process.

• Korean Journal of Materials Research
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• v.28 no.6
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• pp.365-369
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• 2018

We perform density functional theory calculations to study the CO and $O_2$ adsorption chemistry of Pt@X core@shell bimetallic nanoparticles (X = Pd, Rh, Ru, Au, or Ag). To prevent CO-poisoning of Pt nanoparticles, we introduce a Pt@X core-shell nanoparticle model that is composed of exposed surface sites of Pt and facets of X alloying element. We find that Pt@Pd, Pt@Rh, Pt@Ru, and Pt@Ag nanoparticles spatially bind CO and $O_2$, separately, on Pt and X, respectively. Particularly, Pt@Ag nanoparticles show the most well-balanced CO and $O_2$ binding energy values, which are required for facile CO oxidation. On the other hand, the $O_2$ binding energies of Pt@Pd, Pt@Ru, and Pt@Rh nanoparticles are too strong to catalyze further CO oxidation because of the strong oxygen affinity of Pd, Ru, and Rh. The Au shell of Pt@Au nanoparticles preferentially bond CO rather than $O_2$. From a catalysis design perspective, we believe that Pt@Ag is a better-performing Pt-based CO-tolerant CO oxidation catalyst.

• Journal of Pharmaceutical Investigation
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• v.39 no.6
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• pp.423-429
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• 2009

Liposomes have been used as one of the efficient carriers for drug delivery. In this study, anionic liposomes of which surface was modified by using both electrostaic interaction between anionic liposomes and cationically charged BSA molecules at lower pH than isoelectric point (pI) of BSA and denaturation of the BSA-coated liposomes by thermal treatment. The thermally denatured BSA-coated liposomes (DBAL) had mean particle diameter of 125.2${\pm}$1.7 nm and zeta potential value of -22.4${\pm}$4.5 mV. Loading efficiency of model drug, doxorubicin (DOX), into liposomes was 83.0${\pm}$2.6%. Results of in vitro stability study of DBAL in blood plasma showed that the mean particle diameter of DBAL 400 did not increase in blood plasma and adsorption of plasma protein was much less than plain or anionic liposomes. Intracellular uptake of DBAL 400 evaluated by confocal microscopy observation was higher than that of PEG liposomes.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.6
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• pp.357-362
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• 2015

A novel $TiO_2$-Coconut Shell Powder Composite (TCSPS), prepared by the controlled sol-gel method with subsequent heat treatment, was evaluated as an innovative photocatalytic absorbent for the removal of methylene blue. Optimal preparation conditions of TCSPC were obtained by a response surface methodology and a central composite design model. As compared with the results obtained from one-factor-at-a-time experiments, the values were approximated to the nearest condition of these values and the following experimental parameters were set as the optimum : $600^{\circ}C$ calcination temperature and 20 g of coconut shell powder loading amount.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.1
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• pp.15-21
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• 2011

Transport of heavy metals such as Cd is affected by several rate-limiting processes including adsorption and desorption by exchange reactions in soils. In this study, column transport and batch kinetic experiments were performed to assess Cd mobility in a double-layered soil with a reclaimed saline and sodic soil (SSS) as top soil and macroporous granule (MPG) as a bottom layer. For individual soil layer having different physical and chemical properties, Cd was considered to be nonlinear reactivity with the soil matrix in layered soils. The dispersive equation for reactive solutes was solved with three types of boundary conditions for the interface between soil layers. The adsorption of Cd with respect to the saline-sodic sandy loam and the MPG indicated that the nature of the sites or the mechanisms involved in the sorption process of Cd was different and the amounts of Cd for both of samples increases with increasing amounts of equilibrium concentration whereas the amount of Cd adsorbed in saline-sodic sandy loam soil was higher than that in MPG. The results of breakthrough curve indicating relative Cd retardation accompanied by layer material and sequence during leaching showed that the number of pore volumes to reach the maximum relative concentration of 1 increased in the order of MPG, SSS, and double layer of SSS-MPG. Breakthrough curves (BTCs) from column experiments were well predicted with our double-layered model where independently derived solute physical and retention parameters were implemented.

• Journal of the Korean Chemical Society
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• v.22 no.5
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• pp.289-294
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• 1978

In this paper, for the purpose of studying the adsorbed states of benzene and p-xylene molecules on both of the Spheron 6(graphitized carbon) and the Alucer(aluminium oxides), we have calculated the differential molar entropies of adsorption in the Submonolayer region, by the use of statistical thermodynamics. The models we have adopted are two-dimensional gases and the harmonic oscillators. The values calculated in this way are compared with experimental values. As a result, it is believed that the adsorbed benzene molecules are localized on the Spheron 6, whereas on the Alucer it is nonlocalized. The molecular frequency, which is an adjustable parameter and is introduced as a result of oscillator model is $10^{11}\;sec^{-1}$ in the order of magnitude. For the case of p-xylene molecules adsorbed on these adsorbents, an abnormal result is obtained quite prior to the monolayer coverage, contrarily to the expectation of similar results as for the case of benzene.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.11b
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• pp.159-163
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• 1999

Model experiments were conducted to investigate the effect of different fillers on the removal of toner ink. Combinations of different papers (commercial photocopy paper and filler-free paper), fillers (calcium carbonate, kaolin clay, and talc), and chemicals(1-octadecanol, stearic acid, oleic acid, and TOFA) and stearic acid were found to be effective in detachment and agglomeration of toner ink. Furthermore, pH had little effect on toner detachment and agglomeration, indicating both protonated fatty acids and their anions are equally effective. In the presence of either kaolin clay or talc, all these agglomerating agents are equally effective, although a slightly higher dosage(1% for clay and 2% for talc as compared with control) is required, presumably due to the adsorption of chemical by the filler. Calcium carbonate filler, on the other hand, has a significant and adverse effect on the fatty acids used but has little effect on 1-octadecanol with the exception of possible adsorption. While stearic acid is not effective, a much higher level of oleic acid or TOFA is needed when calcium carbonate fillers are present as compared to the filler-free case. Fatty acids react with calcium carbonate to form calcium salts. The availability of fatty acid anion for toner detachment and agglomeration is determined by the solubility of calcium salt of a given fatty acid. Calcium oleate is 10 times more soluble in water than calcium stearate.

• Journal of Microbiology and Biotechnology
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• v.22 no.12
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• pp.1673-1680
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• 2012

In this study, DEAE-corncobs [delignified corncob grits derivatized with 2-(diethylamino)ethyl chloride hydrochloride ($DEAE{\cdot}HCl$)] were prepared as a carrier to immobilize yeast (Saccharomyces cerevisiae) for ethanol production. The immobilized yeast cell reactor produced ethanol under optimized $DEAE{\cdot}HCl$ derivatization and adsorption conditions between yeast cells and the DEAE-corncobs. When delignified corncob grit (3.0 g) was derivatized with 0.5M $DEAE{\cdot}HCl$, the yeast cell suspension ($OD_{600}$ = 3.0) was adsorbed at >90% of the initial cell $OD_{600}$. This amount of adsorbed yeast cells was estimated to be 5.36 mg-dry cells/g-DEAE corncobs. The $Q_{max}$ (the maximum cell adsorption by the carrier) of the DEAE-corncobs was estimated to be 25.1 (mg/g), based on a Languir model biosorption isotherm experiment. When we conducted a batch culture with medium recycling using the immobilized yeast cells, the yeast cells on DEAE-corncobs produced ethanol gradually, according to glucose consumption, without cells detaching from the DEAE-corncobs. We observed under electron microscopy that the yeast cells grew on the surface and in the holes of the DEAE-corncobs. In a future study, DEAE-corncobs and the immobilized yeast cell reactor system will contribute to bioethanol production from biomass hydrolysates.