• Textile Coloration and Finishing
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• v.19 no.3
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• pp.26-36
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• 2007

This study was carried out to treat the aqueous solutions containing reactive dyes(RB19, RR120 and RY179) by the Ozone demand flask method and adsorption process using activated carbon fiber(ACF) which are one of the main pollutants in dye wastewater. Ozone oxidation of three kinds of the reactive dyes was examined to investigate the reactivity of dyes with ozone, competition reaction and ozone utilization on various conditions for single- and multi-solute dye solution. Concentration of dyes was decreased continuously with increasing ozone dosage in the single-solute dye solutions. Competition quotient values were calculated to investigate the preferential oxidation of individual dyes in multi-solute dye solutions. Competition quotients(CQi) and values of the overall utilization efficiency, ${\eta}O_3$, were increased at 40mg/l of ozone dosage in multi-solute dye solutions. ACF(A-15) has much larger specific surface area$(1,584m^2/g-ACF)$ in comparison with granular activated carbon adsorbent (F400, $1,125m^2/g-GAC$), which is commonly used, and most of pores were found to be micropores with pore radius of 2nm and below. It was found that RB19 was most easily adsorbed among the dyes in this study. In the case of PCP (p-chlorophenol) and sucrose, which are single component adsorbate, adsorption capacities of ACF(A-15) were in good agreement with the batch adsorption measurement, and saturation time predicted of ACF columns for these components was also well agreed with practically measured time. But in the case of reactive dyes, which have relatively high molecular weight and aggregated with multi-components, adsorption capacities or saturation time predicted were not agreed with practically measured values.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2215-2226
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• 2000

Adsorption characteristics for homologous xanthates on quartz surface has been investigated by FT-IR spectroscopy to understand the adsorption mechanism in relation with verification of the influence of surfactants on the stability of hydrophilic suspended solids in aqueous system. Contact angle measurement for water droplets on quartz surface treated with xanthate was also conducted as a supplementary study for spectroscopic investigation to grant a reliability to the interpretation of experimental results. It has been observed that monolayer of ethyl xanthate was formed on quartz surface as the adsorption progressed and double layer of ethyl xanthate was formed eventually through the reverse oriented adsorption of xanthate molecules on the monolayer. Similar trend of adsorption to the case of ethyl xanthate was found for propyl and butyl xanthates and adsorption was observed to occur more rapidly as the number of carbon atom in alkyl group of xanthate homologs increased. Thermodynamic aspect of adsorption was discussed using Young's equation and the variation in adsorption rate was examined according to the concentration of ethyl xanthate. Based on the result, it has been concluded that the adsorption features of surfactant on substrate in aquatic system is governed by molecular structure and concentration of surfactant and its residual time in aqueous environment as dissolved state also influences greatly the stability of hydrophilic suspended particles.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1755-1759
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• 2009

Surface structure and molecular orientation of self-assembled monolayers (SAMs) formed by the spontaneous adsorption of tetrahydrothiophene (THT) and thiophene (TP) on Au(111) were investigated by means of scanning tunneling microscopy (STM) and carbon K-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy. STM imaging revealed that THT SAMs have a commensurate (3 ${\times}\;2\sqrt[]{3}$) structure containing structural defects in ordered domains, whereas TP SAMs are composed of randomly adsorbed domains and paired molecular row domains that can be described as an incommensurate packing structure. The NEXAFS spectroscopy study showed that the average tilt angle of the aliphatic THT ring and $\pi$-conjugated TP ring in the SAMs were calculated to be about $30^o\;and\;40^o$, respectively, from the surface normal. It was also observed that the $\pi$* transition peak in the NEXAFS spectrum of the TP SAMs is very weak, suggesting that a strong interaction between $\pi$-electrons and the Au surface arises during the self-assembly of TP molecules. In this study, we have clearly demonstrated that the surface structure and adsorption orientation of organic SAMs on Au(111) are strongly influenced by whether the cyclic ring is saturated or unsaturated.

• Journal of Environmental Health Sciences
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• v.29 no.3
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• pp.50-58
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• 2003

Removal of heavy metal ions (Cd$^{2+}$, Cr$^{3+}$, Cu$^{2+}$, Pb$^{2+}$) by several chitosans was studied and the molecular weight of chitosan was investigated in order to examine the effect of autoclaving. Chitosan were divided into 3 groups (A type, controlled chitosan; B type, autoclaved for 15 min; C type, autoclaved for 60 min). The heavy metal removal capacity and rate of B type chitosan were higher than those of A type and B type chitosan. The molecular weight of chitosan was decreased by the increase of autoclaving time. Therefore, the heavy metal capacity was not well correlated to the molecular weight. Freundlich and Langmuir isotherm was determined from the experimental results of equilibrium adsorption for individual heavy metal ions on chitosan. Langmuir isotherm was well fitted to this experimental data. The heavy metal removal capacity of B type chitosan was in the order of Pb$^{2+}$ > Cu$^{2+}$ > Cd$^{2+}$> Cr$^{3+}$.3+/.$.3+/.

• Journal of the Korean Chemical Society
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• v.22 no.6
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• pp.380-385
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• 1978

Adsorption isotherms of o-xylene on Spheron 6, a graphitized carbon black, are obtained at various temperatures using a quartz beam microbalance. BET plots are made to estimate the molecular area of o-xylene from these isotherms. On Spheron 6, the molecular area of o-xylene (m.p $-25^{\circ}C$) remains constant until the temperature is increased up to $-15^{\circ}C$, but increases abruptly between $-15^{\circ}C$ and $-14^{\circ}C$, and then again remains constant thereafter. These results are interpreted as implying that the adsorbed o-xylene molecules are flatly localized on Spheron 6 with compact packing below $-15^{\circ}C$ while they gain a rotational degree of freedom around the benzene ring at the higher temperature.

• Macromolecular Research
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• v.12 no.4
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• pp.342-351
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• 2004

Poly(ethylene glycol) (PEG1K) and sulfonated PEG (PEG1K-SO$_3$) methacrylate (MA) copolymers have been prepared and characterized. The structures of the synthesized copolymers were confirmed by $^1$H and $^{13}$ C NMR spectroscopy and elemental analysis. The bulk characteristics of the copolymers were evaluated by viscosity and thermal analysis. The surface properties of the copolymers were investigated using dynamic contact angle measurements and electron spectroscopy for chemical analysis. The hydrophilicity of the surfaces modified with PEG1KMA or PEG1K-SO$_3$MA increased, possibly as a result of the orientation of the hydrophilic PEG1KMA/PEG1K-SO$_3$MA chains into the water phase. Platelets adhered less to the surfaces of the copolymers than they did to a polyurethane control. In addition, adhesion of platelets to the copolymer surfaces decreased upon increasing the chain density of PEG1KMA and sulfonated PEG1KMA in the copolymers. Both bacterial adhesion and protein adsorption were significantly reduced on the copolymer surfaces and their levels differ depending on the kind of surface or media.

• Microbiology and Biotechnology Letters
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• v.13 no.3
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• pp.185-189
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• 1985

Extracellular $\beta$-galactosidase from the culture broth of L. sporogenes was purified to apparent homogeniety by procedures including ammonium sulfate fractionation, Sephadex G-200 gel filtration, DEAE-Sephadex A-50 ion exchange chromatography, and Hydroxyapatite adsorption chromatography. The purifying procedures resulted in 347-fold purification with the overall yield of 39.5％ The purified enzyme had a specific activity(using ONPG as a substrate) of about 1, 585 units per mg protein. The molecular weight of the enzyme protein was estimated to be 140, 000 by gel filtration on Sephadex G-200, and SDS-polyacrylamide gel electorphoresis showed that the enzyme consisted of two identical subunits with a molecular weight of 72, 000.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.2
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• pp.108-118
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• 2004

To find out rational design and synthetic strategies toward efficient hydrogen storage materials, molecular modeling and quantum mechanical studies have been carried out on the MOFs(Metal-Organic Frameworks) having various organic linkers and nanocube frameworks. The calculation results about the free volume ratio, surface area, and electron density variation of the frameworks indicated that the capacity of the hydrogen storage of MOFs was largely dependent on the specific surface area and electron localization around benzene ring rather than the free volume of MOFs. The prediction of the modeling study could be supported by the hydrogen adsorption experiments using IRMOF-1 and -3, which showed more enhanced hydrogen storage capacities of IRMOF-3 compared with the IRMOF-1's at both experimental conditions, 77K, ∠ $H_2$ 1 atm and ambient temperature, ∠ $H_2$ 35 atm.

• Journal of Korean Society on Water Environment
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• v.21 no.2
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• pp.205-210
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• 2005

There has been a growing interest in NF membrane for drinking water treatment, because it can remove simultaneously both hardness and hazardous micro pollutants such as pesticides and THM precursors. In this work, a hollow fiber NF membrane known as a composite membrane was employed for the rejection properties of both hydrophilic solutes and micro organic pollutants, where the former was used to evaluate the molecular sieving effect of this membrane and the latter was employed for the investigation of solute-membrane interaction as hydrophobic materials. This membrane effectively rejected the hydrophilic solutes and the permeation of them was mainly controlled by the molecular sieving effects such as molecular weight and molecular width. In the case of all micro organic pollutants, the rejections were varied from 42.2% for Simazine to 91.6% for Malathion, and the parameters related to the steric hindrance could significantly play an important role in the rejection. In the batch type adsorption experiments, all micro organic pollutants were entrapped mildly on the membrane in spite of lower degree compared with that of aromatic compounds, and they were correlated with log K.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.9
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• pp.793-802
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• 2009

Adsorption properties were estimated for the organic silicon compounds (siloxanes) in an actual landfill gas (LFG) using adsorbents such as coconut activated carbon, coal activated carbon, silica gel, sulfur adsorbent, carbonized sludge, and molecular sieve 13X. Coconut activated carbon showed the highest removal efficiency of more than 95%. The desorption of hexamethyldisiloxane (L2) from the adsorbent, however, resulted in the remarkable concentration variation of the compound in the treated gas. Silica gel, which had high adsorption capacity for L2 in single substance adsorption experiment in the other study, could not remove the component in the actual landfill gas while it adsorbed well octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) in the LFG. Therefore the elimination of hexamethyldisiloxane is an important factor to determine the level of total organosilicon compound in pretreated landfill gas. Moreover, the L2 from the actual landfill gas was effectively adsorbed by the serial adsorption test using two columns packed with coconut activated carbon which has the great capacity of siloxanes removal among others. In order to utilize efficiently LFG as a renewable energy, the emission and adsorptive characteristics of the substance to be treated should be considered for the organization, operation, and management of pretreatment process.