• Journal of the Korean Chemical Society
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• v.56 no.2
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• pp.264-273
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• 2012

Five derivatives of phenylthiourea namely: 1-(4-methoxyphenyl)-3-phenylthiourea (1), 1-(4-methylphenyl)-3- phenylthiourea (2), 1-(4-bromophenyl)-3-phenylthiourea (3), 1-(4-chlorophenyl)-3-phenylthiourea (4) and 1-phenylthiourea (5) have been evaluated as new inhibitors for the corrosion of carbon steel in 2 M HCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Potentiodynamic polarization measurements showed that these derivatives are mixed-type inhibitors. The inhibition efficiency was found to increase with inhibitor concentration and decreases with rise in temperature. The thermodynamic parameters of adsorption and activation were determined and discussed. Nyquist plots showed depressed semicircles with their centre below real axis. The adsorption process of studied derivatives on carbon steel surface obeys Temkin adsorption isotherm. The synergistic effect of these derivatives and some anions is discussed from the viewpoint of adsorption models. The electrochemical results are in good agreement with the calculated quantum chemical HOMO and LUMO energies of the tested molecules.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.446-450
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• 2003

Maximum adsorption amount of the mixed culture, $2.06{\times}10^{11} cells/g$ is closed to the sum of that of each bacterial component: $1.39{\times}10^{11}cells/g$ for T. ferrooxidans and $1.08{\times}10^{11}cells/g$ for T. thiooxidans. These indicate that the two bacterial species have almost independent preferential adsorption sites on furnace dust. However, the efficiency of leaching, 35% for mixture, 45% for T.f. and 30% for T.t., was not linearly related to the ratio of adsorption in three different systems even though it was increased in parallel with the bacterial adsorption in the same system.

• Journal of the Korean Ceramic Society
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• v.36 no.6
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• pp.577-582
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• 1999

Activated carbon fibers were prepared from stabilized PAN fibers by chemical activation using hydroxide. The variations in specific surface area amount of iodine adsorption micro-structure and pore size distribution in the activated carbon fibers after the activation process were discussed. In the chemical activation using potassium hydroxide specific surface area of about 2545m2/g and amount of iodine adsorption of 2049 mg/g were obtained at the condition of KOH/fiber ratio of 1 and 800$^{\circ}C$ Nitrogen adsorption isotherms for PAN based activated carbon fibers showed the type I in the Brunauer-Deming-Deming-Teller classification indicating the micro-pores consisting the activated fibers.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.495-500
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• 2009

Activated carbon was used as an adsorbent to capture benzene vapor from gaseous stream of nitrogen in a fixed-bed to obtain the breakthrough data. The deactivation model is used to analyze the adsorption kinetics of benzene vapor 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.11 no.5
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• pp.781-787
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• 2001

The binding of heavy metals by a biosorbent with binary functional groups was mathematically modeled. An FT-IR spectrophotometer analysis was employed to determine the stoichiometry between the protons in the functional groups of alginic acid and lead ions as a model system. The results calculated using an equilibrium constant agreed well with the experimental results obtained under various operating conditions, such as pH and metal ion concentration. It was also shown that the overall adsorption phenomenon of alginic acid was mainly due to its carboxyl groups. The equilibrium constants for each functional group successfully predicted the lead adsorption of ${\alpha}$-cellulose. Furthermore, the biosorption model could predict the adsorption phenomena of two metal ions, lead ions and calcium ions, relatively.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.125-130
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• 2010

In the present work, we have investigated the adsorption efficiency of carbon/iron oxide nanocomposite towards removal of hazardous brilliant green (BG) from aqueous solutions. Carbon/iron oxide nanocomposite was prepared by chemical precipitation and thermal treatment of carbon with ferric nitrate at $750^{\circ}C$. The resulting material was thoroughly characterized by TEM, XRD and TGA. The adsorption studies of BG onto nanocomposite were performed using kinetic and thermodynamic parameters. The adsorption kinetics shows that pseudo-second-order rate equation was fitted better than pseudo-first-order rate equation. The experimental data were analyzed by the Langmuir and Freundlich adsorption isotherms. Equilibrium data was fitted well to the Langmuir model with maximum monolayer adsorption capacity of 64.1 mg/g. The thermodynamic parameters were also deduced for the adsorption of BG onto nanocomposite and the adsorption was found to be spontaneous and endothermic.

• Korean Chemical Engineering Research
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• v.46 no.6
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• pp.1029-1038
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• 2008

Transition-metal-oxide-incorporated hydrotalcites were prepared by hydrothermal reaction of their synthetic mixtures containing precursors of transition metal oxides and their properties of nitrogen dioxide adsorption was investigated. The dispersion of transition metal oxides on the hydrotalcites and the amount and the state of nitrogen dioxide adsorbed on them were examined by using XRD, SEM, XPS, nitrogen adsorption, a gravimetric adsorption system, FT-IR spectroscopy and temperature programmed desorption techniques. Transition metal oxides were mainly incorporated on their surface and the incorporation of iron and nickel oxides to the hydrotalcites increased their adsorption amounts of nitrogen dioxide. The dispersion of iron oxide on the hydrotalcites was effective in increasing the amount of nitrogen dioxide adsorption, while too much amount of iron oxide incorporation reduced the amount of nitrogen dioxide adsorption due to masking of surface basic sites by agglomerated iron oxide. Although the incorporation of iron oxide to the hydrotalcites lowered the adsorption strength of nitrogen dioxide, the incorporation of it with a proper amount enhanced the amount of nitrogen dioxide adsorption and the stability against the hydrothermal treatment.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.309-314
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• 2015

Adsorption of brilliant blue FCF dye from aqueous solution using coconut shell based activated carbon was investigated. Batch experiments were carried out as function of adsorbent dose, initial concentration, contact time and temperature. The equilibrium adsorption data were analyzed by Langmuir and Freundlich model. The results indicate that Freundlich model provides the best correlation of the experimental data. Base on the estimated Freundlich constant (1/n=0.129~0.212), this process could be employed as effective treatment method. Adsorption kinetics experimental data were modeled using the pseudo-first-order and pseudo-second-order kinetic equation. It was shown that pseudo-second-order kinetic equation could best describe the adsorption kinetics. Base on the negative Gibbs free energy value (-4.81~-10.33 kJ/mol) and positive enthalpy value (+78.59 kJ/mol) indicate that the adsorption is spontaneous and endothermic process.

• Macromolecular Research
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• v.16 no.6
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• pp.492-502
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• 2008

This study examined the adsorption of a synthetic cutting fluid and cutting fluid effluent on chitosan and SDS-modified chitosan, Chitosan and SDS-modified chitosan were prepared in form of beads and fibers. A series of batch experiments were carried out as a function of the initial concentration of cutting fluid, contact time and pH of the fluid. The contact angle study suggested that the SDS-modified chitosan was more hydrophobic than chitosan. The Zeta potential study showed that chitosan, SDS-modified chitosan and synthetic cutting fluid had a point of zero charge (PZC) at pH 7.8, 9 and 3.2, respectively. SDS-modified chitosan has a greater adsorption capacity than chitosan. The experimental results show that adsorption capacity of the cutting fluid on 1.0 g of SDS-modified chitosan at pH 3 and for a contact time of 120 min was approximately 2,500 g/kg. The adsorption capacity of chitosan and SDS-modified chitosan increased with decreasing pH. The Langmuir, Freundlich, and Brunauer Emmett and Teller (BET) adsorption models were used to explain the adsorption isotherm. The Langmuir isotherm fitted well with the experimental data of chitosan while the BET isotherm fitted well with the SDS-modified chitosan data. Pseudo first- and second-order kinetic models and intraparticle diffusion model were used to examine the kinetic data. The experimental data was fitted well to a pseudo second-order kinetic model. The significant uptake of cutting fluid on chitosan and SDS-modified chitosan were demonstrated by FT-IR spectroscopy, SEM and heat of combustion.

• Korean Chemical Engineering Research
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• v.44 no.2
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• pp.172-178
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• 2006

Mesoporous silicate materials have been used as adsorbents for the removal of heavy metals from water by introducing functional groups such as thiol and amine. In this research, it was investigated whether surfactants used as templating agents in synthetic processes can act as adsorption sites for heavy metals. Three mesoporous silicates-SBA-15, MCM-41, and HMS were synthesized using, respectively, block copolymer, hexadecyltrimethylammoniumbromide (HDTMA), and dodecyamine as surfactants. X-ray diffraction and $N_2$ gas adsorption analysis confirmed that the mesoporous silicates were well prepared and FT-IR spectra resulted in the existence of the surfactants in as-synthesized mesoporous silicates and the removal of surfactants after calcination. The interactions between $Pb^{2+}$ ions and the mesoporous silicate materials with/without surfactants were observed. In adsorption kinetic experiments, it revealed that the calcined mesoporous silicates and the surfactant-loaded SBA-15 almost had no adsorption capacity for $Pb^{2+}$ ions. In contrast, the surfactant-loaded MCM-41 and HMS showed, respectively, the adsorption capacities of 26.60 and 115.16 mg/g which were acquired through the fits of adsorption kinetic data to the pseudo second order kinetic model. The adsorption capacities were comparable to those of other mesoporous adsorbents for heavy metals.