• Journal of the Korean Electrochemical Society
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• v.7 no.4
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• pp.194-200
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• 2004

The constant correlation factors between the Temkin and the Langmuir or the Frumkin adsorption isotherms of over-potentially deposited hydrogen (OPD H) for the cathodic H2 evolution reaction (HER) at poly-Pt and Re/0.5M $H_2SO_4$ and poly-Ni/0.05 M KOH aqueous electrolyte interfaces have been experimentally and consistently found using the phase-shift method. At intermediate values of the fractional surface coverage $(\theta),\;i.e.,\;02<{\theta}<0.8$, the Langmuir and Temkin adsorption isotherms of OPD H for the cathodic HER are correlated to each other even though the adsorption conditions or processes are different from each other. At the same range of $\theta$, correspondingly, the Frumkin and Temkin adsorption isotherms of OPD H for the cathodic HER are correlated to each other. The equilibrium constants $(K_o)$ for the Temkin adsorption isotherms $({\theta}\;vs.\; E)$ are consistently ca. 10 times greater than those (K, Ko) for the corresponding Langmuir or Frumkin adsorption isotherms ($({\theta}\;vs.\; E)$. The interaction parameters (g) for the Temkin adsorption isotherms $({\theta}\;vs.\; E)$ are consistently ra. 4.6 greater than those (g) for the corresponding Langmuir or Frumkin adsorption isotherms $({\theta}\;vs.\; E)$. These numbers (10 times and 4.6) can be taken as constant correlation factors between the corresponding adsolftion isotherms (Temkin, Langmuir, Frumkin) at the interfaces. The Temkin adsorption isotherm corresponding to the Langmuir or the Frumkin adsorption isotherm, and vice versa, can be effectively verified or confirmed using the constant correlation factors. Both the phase-shift methodand constant correlation factors are useful and effective for determining or confirming the suitable adsorption isotherms (Temkin, Langmuir, Frumkin) of intermediates for sequential reactions in electrochemical systems.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.313-317
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• 2023

In this study, the physicochemical characterization and adsorption performance of air pollutants (VOCs, SO₂, and CO₂) were evaluated for the recycling of zeolite used in the ion exchange process. The surface characteristics of the zeolite used were confirmed through Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) analysis, and the composition and specific surface area were measured through X-Ray Fluorescence (XRF) and Brunauer-Emmett-Teller (BET). There was no change in the surface properties of the used zeolite, but the content of potassium and calcium increased and the specific surface area decreased. The toluene, sulfur oxides, and carbon dioxide adsorption performance of the used zeolite was evaluated, and it was confirmed that the performance was improved compared to the fresh zeolite. In particular, for toluene and sulfur oxides, the adsorption amount increased by 2.6 times and 2.3 times, respectively, which might be due to the enhancement of the polymerization reaction and the increase of the base point, according to the composition of the used zeolite.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.532-538
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• 2006

The carbonization and activation conditions for the PAN-based ACF of various grade were investigated to obtain the optimun activation condition with high surface area. And the surface properties and the absorption performance of toxic gas for terror were examined toward the PAN-ACF with the highest surface area. In the test results the surface area increased with increase of the activation temperature, but decreased with increase of the carbonization temperature. After carbonization condition ($900^{\circ}C$-15min) and activation condition ($900^{\circ}C$-30 min), we got the ACF with the highest surface area of $1204m^2/g$. In the absorption test of iodine and toxic gas for terror, this ACF showed more excellent absorption performance than the existing carbon-based adsorbent. Also, in order to give the function characteristic for a selective absorption, the stable nanoparticles of the Ag, Pt, Cu, Pd were prepared and impregnated on the PAN-based ACF in replacement of the existing method supporting metal catalysis. And were analyzed the surface characteristics and the $SO_{2}$ adsorption characteristics. In the $SO_{2}$ absorption performance test of the PAN-ACF with the impregnated nanoparticles, it wasn't change breakthrough time of Ag, Pt, Cu nanoparticle supported the PAN-ACF comparing with breakthrough time (326 sec) of the non supported PAN-ACF but Pd nanoparticle supported the PAN-ACF achieved excellent $SO_{2}$ absorption performance which has break-through time 925 sec.

• Journal of Applied Biological Chemistry
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• v.65 no.4
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• pp.457-462
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• 2022

Manganese (Mn) exists in various oxidation states and Mn(II) is the most mobile species of Mn, which is toxic to plants and limits their growth. Therefore, the purpose of this study was to reduce Mn toxicity by immobilizing Mn using various adsorbents including iron oxides and calcium compounds. Ferrihydrite, schwertmannite, goethite were synthesized, which was confirmed by X-ray diffraction. Hematite was purchased and used as Mn adsorbent. Calcium compounds such as CaNO₃, CaSO₄, and CaCO₃ were used to increase pH and oxidize Mn. For Mn adsorption, Mn(II) solution was reacted with four iron oxides, CaNO₃, CaSO₄, and CaCO₃ for 24 hours, filtered, and the remaining Mn concentrations in the solution were analyzed by inductively coupled plasma optical emission spectroscopy. The adsorption rate and adsorption isotherm were calculated. Among iron oxides, the adsorption rate was highest for hematite followed by ferrihyrite, but goethite and schwertmannite did not adsorb Mn. In the case of calcium compounds, the adsorption rate was high in the order of CaCO₃>CaNO₃>CaSO₄. In conclusion, treatment of CaCO₃ was the most effective in reducing Mn toxicity by increasing pH.

• Journal of Electrochemical Science and Technology
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• v.7 no.4
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• pp.251-262
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• 2016

The corrosion protection of mild steel in 1M HCl and 0.5M $H_2SO_4$ solutions by ethanol extract of Vernonia amygdalina (VA) was studied using a combination of experimental and computational methods. The obtained results revealed that VA reduced the corrosion of mild steel in both environments and inhibition efficiency increased with VA concentration but decreased with prolonged exposure. Electrochemical results showed that the extract functioned via mixed corrosion inhibiting mechanism by adsorption of some organic constituents of the extract on the metal/acid interface. Findings from infrared spectroscopy and electron microscopy all confirmed that VA retarded mild steel corrosion in both 1M HCl and 0.5M $H_2SO_4$ through an adsorption process. The adsorption behavior of selected constituents of the extract was modeled using density functional theory computations.

• Resources Recycling
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• v.29 no.5
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• pp.38-47
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• 2020

In this study, factors affecting the adsorption reaction for the separation/recovery of V and W using Lewatit monoplus MP 600, a strong basic anion exchange resin, from the leachate obtained through the soda roasting-water leaching process from the spent SCR DeNO_X catalyst investigated and the adsorption mechanism was discussed based on the results. In the case of the mixed solution of V and W, both ions showed a high adsorption ratio at pH 2-6, but the adsorption of W was greatly reduced at pH 8. In the adsorption isothermal experiment, both V and W were fitted well at the Langmuir adsorption isotherm, and the reaction kinetics were fitted well at pseudo-second-order. As a result of conducting an adsorption experiment by adjusting the pH with H₂SO₄ to remove Si, which inhibits the adsorption of V and W from the leachate, the lowest W adsorption ratio was shown at pH 8.5. Desorption of W was hardly achieved in strongly acidic solutions, and desorption of V was well performed in both strongly acidic and strongly basic solutions.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1625-1631
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• 2013

We report a facile synthetic approach of high-quality chromium(III) terephthalate [MIL-101(Cr)] by acetate-assisted method in the absence of toxic HF. Results indicate that the morphology and surface area of the MIL-101(Cr) can be tuned by modifying the molar ratio of acetate/$Cr(NO_3)_3$. The Brunauer-Emmett-Teller (BET) surface area of MIL-101(Cr) synthesized at the optimized condition can exceed 3300 $m^2/g$. It is confirmed that acetate could promote the dissolution of di-carboxylic linker and accelerate the nucleation ratio. So the pure and small size of MIL-101(Cr) with clean pores can be obtained. $CO_2$, $CH_4$ and $N_2$ adsorption isotherms of the samples are studied at 298 K and 313 K. Compared with the traditional method, MIL-101(Cr) synthesized by acetate-assisted method possess enhanced $CO_2$ selective adsorption capacity. At 1.0 bar 298 K, it exhibits 47% enhanced $CO_2$ adsorption capacity. This may be attributed to the high surface area together with clean pores of MIL-101(Cr).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.592-599
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• 2018

The kinetics and thermodynamics of the adsorption of acid blue 40 from an aqueous solution by activated carbon were examined as a function of the activated carbon dose, pH, temperature, contact time, and initial concentration. The adsorption efficiency in a bathtub was increased at pH 3 and pH 11 due to the presence of sufonate ions ($SO_3{^-}$) and amine ions ($NH_2{^+}$). The equilibrium adsorption data were fitted to the Langmuir, Freundlich and Temkin isotherms. The results indicated that the Langmuir model provides the best correlation of the experimental data. The separation factor of the Langmuir and Freundlich model showed that the adsorption treatment of acid blue 40 by activated carbon could be an effective adsorption process. The adsorption energy determined by the Temkin equation showed that the adsorption step is a physical adsorption process. Kinetics analysis of the adsorption process of acid blue 40 on activated carbon showed that a pseudo second order kinetic model is more consistent than a pseudo second order kinetic model. The estimated activation energy was 42.308 kJ/mol. The enthalpy change (80.088 J/mol) indicated an endothermic process. The free energy change (-0.0553 ~ -5.5855 kJ/mol) showed that the spontaneity of the process increased with increasing adsorption temperature.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.4
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• pp.327-332
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• 1987

Soil samples were collected from the paddy soils growing two crops of rice and garlic in Kyung-pook province. To obtain the basic information on the application of S-fertilizer in the garlic field, the adsorption and release amount of $SO_4{^{-2}}$ in subsoil samples were determined. The ranges of $SO_4{^{-2}}$ contents in surface and sub-soil were 59-117 and 34-102 ppm, respectively. The amount of $SO_4{^{-2}}$ adsorbed by soil samples was found to be more at lower pH and higher concentration of $SO_4{^{-2}}$. The $SO_4{^{-2}}$ adsorption constants in Freundlich equation tended to be higher at lower pH. It is apparent that most of $SO_4{^{-2}}$ was released in the first extraction. However, the lower the pH of extracted solution, the more the $SO_4{^{-2}}$ contents was released by distilled water.

• Bulletin of the Korean Chemical Society
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• v.16 no.2
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• pp.130-134
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• 1995

Surface-enhanced Raman (SER) scattering of 2-cyanonaphthalene (2-CN) has been investigated in silver sol. Addition of halide ions was needed to obtain authentic SER spectra of the molecule. The SER spectra thus obtained exhibited a slight but noticeable dependence on the kind of halide ions used. This halide-dependent spectral variation was attributed to the orientational change of molecule on silver sol surface. A possible mechanism for such an orientational change is proposed in terms of the competitive adsorption of 2-CN with halide ions on the so-called halide-specific sites.