• Journal of the Korean GEO-environmental Society
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• v.13 no.6
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• pp.27-31
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• 2012

This study was designed to examine the feasibility of functionalized mesoporous silica as the adsorbent for benzene, toluene, ethylbenzene, and xylene isomers (BTEX) in groundwater. p-Xylene was used as the model compound of BTEX. A series of functionalized mesoporous silica with MCM-41 type of structure was synthesized using a co-condensation method. Monoamine, triamine, nitrile, phenyl, and octyl groups were functionalized to the mesoporous silica structure. Adsorption sites for p-Xylene in a functionalized mesoporous silica were Si-O-Si covalent bond, the surfactant, and the functional group. Octyl-functionalized mesoporous silica with stearyltrimethylammonium chloride as a surfactant showed the highest adsorption ability. The maximum xylene adsorption capacity of the octyl-functionalized mesoporous silica with stearyltrimethylammonium chloride based on Langmuir model was 4.17 mmol/g on $20^{\circ}C$, which was 2.9 times higher than that of MCM-41.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.8
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• pp.450-457
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• 2015

In this research a adsorbent, PVA-Zeolite bead, was prepared by immobilizing zeolite with PVA. The results of XRD and SEM analysis showed that the prepared PVA-Zeolite beads had porous structure and the zeolite particles were in mobilized within the internal matrix of the beads. The adsorption properties of Sr ion and Cs ion with the adsorbent were studied by different parameters such as effect of pH, adsorption rate, and adsorption isotherm. The adsorption of Sr ion and Cs ion reached equilibrium after 540 minutes. The adsorption kinetics of both ions by the PVA-Zeolite beads were fitted well by the pseudo-second-order model more than pseudo-first-order model. The equilibrium data fitted well with Langmuir isotherm model. The maximum adsorption capacities of Sr ion and Cs ion calculated from Langmuir isotherm model were 52.08 mg/g and 58.14 mg/g, respectively. The external mass transfer step was very fast compared to the intra-particle diffusion step in the adsorption process of Cs ion and Sr ion by the PVA-Zeolite beads. This result implied that the rate controlling step was the intra-particle diffusion step.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.4
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• pp.439-445
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• 2008

Sawdust is considered one of the cheapest and abundantly available adsorbents, and it is not necessary to regenerate. The spent sawdust can be incinerated or reused as a fuel. The sawdust adsorption can be applied to the removal of color and metal cations from the wastewater. The aim of this study was to evaluate the adsorptive capacities of sawdust with respect to color, COD, SS, turbidity, metal cation from textile wastewater. Langmuir, Freundlich, BET and Sips adsorption isotherm were obtained for the sawdust adsorption of Fe(III). The effects of particle size and amount of sawdust on the adsorption of Fe(III) were also studied. COD, SS, color, turbidity and Fe(III) removal efficiencies were examined at the continuous fixed-bed adsorption test. It was showed the removal efficiencies of SS 50.0%, Fe(III) 25.0%, turbidity 79.4%, color 48.6% and COD 50.9%. In addition, the changes of surface structure between before and after adsorption were investigated through SEM analysis. It is confirmed that the waste sawdust can be successfully used as an adsorbent for wastewater treatment.

• Membrane and Water Treatment
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• v.8 no.3
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• pp.259-277
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• 2017

Adsorption is a widely used technique for the removal of dyes from wastewaters by variety of adsorbents. In this work, the main focus is on the potential assessment of anion exchange membrane for the removal of different dyes using batch system and investigation of experimental data by applying various kinetic and thermodynamic models. The removal of anionic dyes i.e., Eosin-B, Eriochrome Black-T and Congo Red by anion exchange membrane BII from aqueous solution was carried out and effect of various parameters such as contact time, membrane dosage, temperature and ionic strength on the percentage removal of anionic dyes was studied. The experimental data was assessed by kinetic models namely pseudo-first-order, pseudo-second-order, Elovich liquid film diffusion, Bangham and the modified Freundlich models equation have been used to analyze the experimental data. These results indicate that the adsorption of these anionic dyes on BII follows pseudo-second-order kinetics with maximum values of regression coefficient (0.992-0.998) for all the systems. The adsorption of dyes was more suitable to be controlled by a liquid film diffusion mechanism. The adsorptive removal of dye Eosin-B and Eriochrome Black-T were decreased with temperature and thermodynamic parameters such as free energy (${\Delta}G^o$), enthalpy (${\Delta}H^o$) and entropy (${\Delta}S^o$) for adsorption of dyes on membrane BII were calculated at 298 K, 308 K and 318 K. The values of enthalpy and entropy were negative for EB and EBT representing that the adsorption of these dyes on BII is physiosorptive and exothermic in nature. Whereas the positive values of enthalpy and entropy for CR adsorption on BII, indicating that its adsorption is endothermic and spontaneous in nature. It is evident from this study that anion exchange membrane has shown good potential for the removal of dyes from aqueous solution and it can be used as adsorbent for dues removal on commercial levels.

• Korean Journal of Optics and Photonics
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• v.15 no.6
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• pp.531-538
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• 2004

Studies of adsorption isotherms with sharp step-wise layer condensation help us to better understanding of two dimensional layers. For this, an adsorption isotherm apparatus, using a phase modulated ellipsometric technique, has been constructed and an adsorption experiment has been performed. With subatomic scale resolution(∼0.3 $\AA$), the adsorption processes could be observed by ellipsometric signals. On measurement of multilayer adsorption of argon on highly oriented pyrolytic graphite(HOPG), thousands of adsorbed layers were observed at 34.04 K, which suggests that the adsorption is completely wet. On the contrary nine sharp layers of steps for adsorptions and desorptions were observed at 67.05 K. These isotherms obtained can provide a lot of information about thermodynamic states, bonding energies between adsobate and substrate, and structure transitions in the adsorbed film.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.4
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• pp.443-454
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• 2006

Purpose: This study aims to get the fundamental data which is necessary to the development direction of implant surface treatment hereafter, based on the understanding the surface structure and properties of titanium which is suitable for the absorption of initial tissue fluid by researching effects of additional surface treatments fir sandblasted with large git and acid-etched(SLA) titanium on surface micro-roughness, static wettability, fibronectin adsorption Materials and Method: In the Control groups, the commercial pure titanium disks which is 10mm in diameter and 2mm in thickness were treated with HCI after sandblasting with 50$\mu$m $Al_2O_3$. The experiment groups were made an experiment each by being treated with 1) 22.5% nitric acid according to SLA+ASTM F86 protocol, 2) SLA+30% peroxide, 3) SLA+NaOH, 4) SLA+ Oxalic acid, and 5) SLA+600$^{\circ}C$ heating. In each group, the value of Ra and RMS which are the gauges of surface roughness was measured, surface wettability was measured by analyzing with Sessile drop method, and fibronectin adsorption was measured with immunological assay. The significance of each group was verified by (SPSS, ver.10.0 SPSS Inc.) Kruskal-Wallis Test. (α=0.05) And the correlation significance between Surface micro-roughness and surface wettability. surface roughness and fibronectin adsorption, and surface wettability and fibronectin adsorption was tested by Spearman's correlation analysis. Result: All measure groups showed the significant differences in surface micro-roughness, surface wettability, and fibronectin adsorption. (p<0.05) There was no significance in correlation among the surface micro-roughness, surface wettability, and fibronectin adsorption. (p>0.05) Conclusion: Surface micro-roughness and surface wettability rarely affected the absorption of initial tissue fluid on the surface of titanium.

• 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.

• Journal of Environmental Science International
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• v.28 no.6
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• pp.561-570
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• 2019

A zeolitic material (Z-Y2) was synthesized from Coal Fly Ash (CFA) using a fusion/hydrothermal method under low-alkali condition (NaOH/CFA = 0.6). The adsorption performance of the prepared zeolite was evaluated by monitoring its removal efficiencies for Sr and Cs ions, which are well-known as significant radionuclides in liquid radioactive waste. The XRD (X-ray diffraction) patterns of the synthesized Z-Y2 indicated that a Na-A type zeolite was formed from raw coal fly ash. The SEM (scanning electron microscope) images also showed that a cubic crystal structure of size $1{\sim}3{\mu}m$ was formed on its surface. In the adsorption kinetic analysis, the adsorption of Sr and Cs ions on Z-Y2 fitted the pseudo-second-order kinetic model well, instead of the pseudo-first-order kinetic model. The second-order kinetic rate constant ($k_2$) was determined to be $0.0614g/mmol{\cdot}min$ for Sr and $1.8172g/mmol{\cdot}min$ for Cs. The adsorption equilibria of Sr and Cs ions on Z-Y2 were fitted successfully by Langmuir model. The maximum adsorption capacity ($q_m$) of Sr and Cs was calculated as 1.6846 mmol/g and 1.2055 mmol/g, respectively. The maximum desorption capacity ($q_{dm}$) of the Na ions estimated via the Langmuir desorption model was 2.4196 mmol/g for Sr and 2.1870 mmol/g for Cs. The molar ratio of the desorption/adsorption capacity ($q_{dm}/q_m$) was determined to be 1.44 for Na/Sr and 1.81 for Na/Cs, indicating that the amounts of desorbed Na ions and adsorbed Sr and Cs ions did not yield an equimolar ratio when using Z-Y2.

• Analytical Science and Technology
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• v.20 no.3
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• pp.193-197
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• 2007

In this study, the effect of metal treatment on granular activated carbon (GAC) was investigated in the context of phenol adsorption. Cobalt(II) nitrate, and zinc(II) nitrate solution were used for metal treated. The specific surface area and the pore structure were evaluated from nitrogen adsorption data at 77 K. The phenol adsorption rates onto GAC were measured by UV-Vis spectrophotometer. Iodine adsorption capacity of Co-GAC is much better then that of the GAC. The Co-GAC with mesopore is more efficient than other adsorbents for the adsorption of polymer such as methyleneblue. The adsorption capacity of reference-GAC and metal-GAC were increased in order of Co-GAC>Zn-GAC>Reference-GAC, in spite of a decrease in specific surface area which was resulted from pore blocking by metal.

• Proceedings of the Korean Vacuum Society Conference
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• 2007.02a
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• pp.76-76
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• 2007