• Title/Summary/Keyword: Temkin

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Atmospheric Effects on Corrosion of Iron in Borate Buffer Solution (Borate 완충용액에서 철의 부식에 대한 대기의 영향)

  • Kim, Hyun-Chul;Kim, Younkyoo
    • Journal of the Korean Chemical Society
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    • v.56 no.6
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    • pp.673-678
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    • 2012
  • Using potentiodynamic and linear polarization method, the atmospheric effect on the corrosion of iron in borate buffer solution was investigated. The corrosion of iron was heavily influenced by the degree of oxygen concentration. The supply of reduction current was increased by the reduction of dissolved oxygen, and the corrosion potential of iron was shifted to the positive side. The $OH^-$ ion, which was produced through the reduction of either water or oxygen, significantly increased the $OH^-$ ion concentration inside of the electrical double layers of iron electrode, and facilitated the adsorption of $OH^-$ ion on the surface of the iron electrode. The adsorption of $OH^-$ ion on the iron electrode can be explained either by Langmuir isotherm or by Temkin logarithmic isotherm.

Comparative Study of Corrosion Inhibition in Acidic and Neutral Chloride Media by Some Amino Acids (염산과 NaCl 수용액에서 알루미늄의 부식에 미치는 아미노산의 부식억제효과)

  • Yoon, Jonghwa;Kim, Younkyoo
    • Journal of the Korean Chemical Society
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    • v.62 no.5
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    • pp.364-371
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    • 2018
  • Inhibition effects of alanine (Ala), histidine (His), methionine (Met) on the corrosion of aluminum were investigated in deaerated 0.5 M HCl and NaCl solution. In HCl solution the inhibition efficiency for the aluminum corrosion depended on the cathodic inhibition, and the inhibition efficiency was increased in the order of Met$10^{-4\;}M$ the adsorption process can be explained by Langmuir isotherm, however, in the case of higher concentration by Temkin logarithmic isotherm due to the interaction between the adsorbed molecules.

Chloride Ion Effects on Anodic Dissolution of Copper in Aqueous NaCl Solutions under Argon Atmosphere (아르곤 분위기의 NaCl 수용액에서 구리의 산화 용해반응에 미치는 염화이온의 영향)

  • Chon, Jung-Kyoon;Kim, Youn-Kyoo
    • Journal of the Korean Electrochemical Society
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    • v.11 no.3
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    • pp.159-164
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    • 2008
  • We investigated chloride ion effects on anodic dissolution of copper using potentiodynamic method, cyclic voltammtery, chronoamperometry and chronocoulometry. The anodic dissolution reaction of copper in NaCl solution under argon atmosphere is $Cu+2Cl^{-}{\rightleftharpoons}{CuCl_2}^{-}+e^-$ and chloride ion adsorption process in copper surface can be explained by Temkin isotherm.

Comparative adsorption of crude oil using mango (Mangnifera indica) shell and mango shell activated carbon

  • Olufemi, Babatope Abimbola;Otolorin, Funmilayo
    • Environmental Engineering Research
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    • v.22 no.4
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    • pp.384-392
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    • 2017
  • Mango shell (MS) and mango shell activated carbon (MSAC) was used to adsorb crude oil from water at various experimental conditions. The MSAC was prepared by carbonization at $450^{\circ}C$ and chemical activation using strong $H_3PO_4$ acid. The adsorbents were characterized with Fourier Transform Infrared spectroscopy. Investigations carried out included the effects of parametric variations of different adsorbate dose, adsorbent dose, time, temperature, pH and mixing speed on the adsorption of crude oil. The equilibrium isotherm for the adsorption process was determined using Langmuir, Freundlich, Temkin and Dubinin Radushkevich isotherm models. Temkin isotherm was found to fit the equilibrium data reasonably well than others. The result demonstrated that MSAC was more effective for crude oil adsorption than raw mango shell. Optimum conditions were also presented. The enhanced effect from activation was justified statistically using Analysis of Variance and Bonferroni-Holm Posthoc significance test. The pseudo first order kinetics gave a better fit for crude oil adsorption with both MS and MSAC.

Inhibition Effect of a Few Amino Acids on the Corrosion of Copper in Aerated Artificial Sea Water (공기가 포화된 인공해수에서 몇 가지 아미노산의 구리 부식 억제 효과)

  • Kim, Youn-Kyoo
    • Journal of the Korean Chemical Society
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    • v.54 no.6
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    • pp.680-686
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    • 2010
  • Inhibition effects of alanine(Ala), asparagine(Asn), aspartic acid(Asp), glutamine(Gln) and methionine(Met) on the corrosion of copper were investigated in aerated artificial sea water. Amino acid adsorption process in copper surface can be explained by Temkin logarithmic isotherm due to the interaction between the adsorbed molecules. The inhibition efficiency for the copper corrosion depended on the concentration of amino acids.

Effect of S-AITA on Mild Steel Corrosion in Acidic Medium

  • Chandrasekaran, V.;Saravanan, J.
    • Corrosion Science and Technology
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    • v.5 no.5
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    • pp.160-167
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    • 2006
  • S-Acetyl Isothiourea Acetate (S-AITA) was synthesized in the laboratory and this influence on the inhibition of corrosion of mild steel in 1.11 N hydrochloric and 1.12 N sulphuric acids was investigated by weight loss and potentiostatic polarization techniques at 303K, 353K and 403K. These results were confirmed by the impedance technique. The inhibition efficiency increased with increase in concentration of inhibitor and decreased with rise in temperature from 303K to 403K. The maximum inhibition efficiency of S-AITA was found to be 99.95% (0.5% of S-AITA) at 303K in sulphuric acid. The adsorption of this compound on the mild steel surface from the acids has been found to obey Temkin's adsorption isotherm. The potentiostatic polarization results revealed that S-AITA was a mixed type inhibitor. Some thermodynamic parameters i.e., activation energy (Ea), free energy of adsorption (${\Delta}G_{ads}$), enthalpy of adsorption (${\Delta}H$) and entropy of adsorption (${\Delta}S$) were also calculated from weight loss data.

Inhibition Effects of Some Amino Acids on the Corrosion of Nickel in Hydrochloric Acid and Sulfuric Acid (염산과 황산 용액에서 니켈의 부식에 미치는 아미노산의 부식억제효과)

  • Kim, Younkyoo
    • Journal of the Korean Chemical Society
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    • v.59 no.2
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    • pp.125-131
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    • 2015
  • Inhibition effects of histidine (His), methionine (Met) on the corrosion of nickel were investigated in deaerated 0.5 M HCl and 0.5 M $H_2SO_4$ solution. All the inhibition efficiency for the nickel corrosion depended on the anodic inhibition. Amino acid adsorption process on nickel surface in the solution of HCl can be explained by modified Langmuir isotherm, however, in the solution of $H_2SO_4$ by Temkin logarithmic isotherm due to the interaction between the adsorbed molecules. The molecule of histidine dissolved in HCl-solution were physically adsorbed due to the electrostatic interaction between the surface of {$Ni-Cl^-$} and the {$-NH{_3}^+$} and {$-NH^+=$} of His. However the other cases of adsorption in this investigation can be explained by chemical adsorption between the empty d-orbital of Ni and the lone pair of electron in His and Met.

Equilibrium Kinetics and Thermodynamic Parameters Studies for Eosin Yellow Adsorption by Activated Carbon (활성탄에 의한 Eosin Yellow의 흡착에 대한 평형, 동력학 및 열역학 파라미터에 관한 연구)

  • Lee, Jong Jib
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.5
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    • pp.3319-3326
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    • 2014
  • Eosin yellow is used a dye and colorant but it is harmful toxic substance. In this paper, batch adsorption studies were carried out for equilibrium, kinetics and thermodynamic parameters for eosin yellow adsorption by activated carbon with varying the operating variables like pH, initial concentration, contact time. Equilibrium adsorption data were fitted into Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. By estimated Langmuir constant value, $R_L$=0.067-0.083, and Freundlich constant value, $\frac{1}{n}=0.237-0.267$, this process could be employed as effective treatment for removal of eosin yellow. From calculated Temkin constant, value, B=1.868-2.855 J/mol, and Dubinin-Radushkevich constant, value, E=5.345-5.735 kJ/mol, this adsorption process is physical adsorption. From kinetic experiments, the adsorption process were found to confirm to the pseudo second order model with good correlation coefficient($r^2$=0.995-0.998). The mechanism of the adsorption process was determined two step like as boundary and intraparticle diffusion.

Applicability of Theoretical Adsorption Models for Studies on Adsorption Properties of Adsorbents(III) (흡착제의 흡착특성 규명을 위한 흡착모델의 적용성 평가(III) - 열역학적 특성을 중심으로)

  • Na, Choon-Ki;Jeong, Jin-Hwa;Park, Hyun-Ju
    • Journal of Korean Society of Environmental Engineers
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    • v.34 no.4
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    • pp.260-269
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    • 2012
  • The aim of this study is to evaluate the applicability of adsorption models for understanding the thermodynamic properties of adsorption process. For this study, the adsorption isotherm data of $NO_3$-N ion onto a commercial anion exchange resin obtained at various experimental conditions, i.e. different initial concentrations of adsorbate, different dosages of adsorbent, and different temperatures, were used in calculating the thermodynamic parameters and the adsorption energy of adsorption process. The Gibbs free energy change (${\Delta}G^0$) of adsorption process could be calculated using the Langmuir constant $b_M$ as well as the Sips constant, even though the results were significantly dependant on the experimental conditions. The thermodynamic parameters such as standard enthalpy change (${\Delta}H^0$), standard entropy change (${\Delta}S^0$) and ${\Delta}G^0$ could be calculated by using the experimental data obtained at different temperatures, if the adsorption data well fitted to the Langmuir isotherm model and the plot of ln b versus 1/T gives a straight line. As an alternative, the empirical equilibrium constant(K) defined as $q_e/C_e$ could be used for evaluating the thermodynamic parameters instead of the Langmuir constant. The results from the applications of D-R model and Temkin model to evaluate the adsorption energy suggest that the D-R model is better than Temkin model for describing the experimental data, and the availability of Temkin model is highly limited by the experimental conditions. Although adsorption energies determined using D-R model show significantly different values depending on the experimental conditions, they were sufficient to show that the adsorption of $NO_3$-N onto anion exchange resin is an endothermic process and an ion-exchange process.

Study on of Process Parameters for Adsorption of Reactive Orange 16 Dye by Activated Carbon (활성탄에 의한 Reactive Orange 16 염료 흡착에 대한 공정 파라미터 연구)

  • Lee, Jong Jib
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.7
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    • pp.667-674
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    • 2020
  • The adsorption of reactive orange 16 (RO 16) dye by activated carbon was investigated using the amount of adsorbent, pH, initial concentration, contact time and temperature as adsorption variables. The investigated process parameters were separation coefficient, rate constant, rate controlling step, activation energy, enthalpy, entropy, and free energy. The adsorption of RO 16 was the highest at pH 3 due to the electrostatic attraction between the cations (H+) on the surface of the activated carbon and the sulfonate ions and hydroxy ions possessed by RO 16. Isotherm data were fitted into Langmuir, Freundlich and Temkin isotherm models by applying the evaluated separation factor of Langmuir (RL=0.459~0.491) and Freundlich (1/n=0.398~0.441). Therefore, the adsorption operation of RO 16 by activated carbon was confirmed as an appropriate removal method. Temkin's adsorption energy indicated that this adsorption process was physical adsorption. The adsorption kinetics studies showed that the adsorption of RO 16 follows the pseudo-second-order kinetic model and that the rate controlling step in the adsorption process was the intraparticle diffusion step. The positive enthalpy change indicated an endothermic process. The negative Gibbs free energy change decreased in the order of -3.16 <-11.60 <-14.01 kJ/mol as the temperature increased. Therefore, it was shown that the spontaneity of the adsorption process of RO 16 increases with increasing temperature.