• Applied Chemistry for Engineering
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• v.31 no.6
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• pp.639-645
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• 2020

Among the components of redox flow battery (RFB), the electrode serves as a diffusion layer of an electrolyte and a path for electrons and also is a major component that directly affects the RFB performance. In this paper, chloric/sulfuric mixed acidwas used as a supporting electrolyte in RFB system with Fe2+/Fe3+ and V2+/V3+ as redox couple. The optimum electrode and activation temperature were suggested by comparing the capacity, coulombic efficiency and energy efficiency according to the electrode type and activation temperature. In the RFB single cell evaluation using 5 types of carbon electrodes used in the experiments, all of them showed close to the theoretical capacity to retain the reliability of the evaluation results. GFD4EA showed relatively excellent energy efficiency and charge/discharge capacity. In order to investigate the electrochemical performance according to the activation temperature, GFD4EA electrode was activated by heat treatment at different temperatures of 400, 450, 500, 600 and 700 ℃ under an air atmosphere. Changes in physical properties before and after the activation were observed using electrode mass retention, scanning electron microscope (SEM), XPS analysis, and electrochemical performance was compared by conducting RFB single evaluation using electrodes activated at each temperature given above.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.243-248
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• 2011

Pt deposited porous carbon nanofibers was prepared as a highly sensitive material of hydrogen gas sensor operating at room temperature. Nanofibers was obtained by electrospinning method using polyacrylonitrile as a carbon precursor and then thermally treated for carbon nanofibers. Chemical activation of carbon nanofibers was carried out to enlarge specific surface area up to $2093m^2/g$. Sputtered Pt layer was uniformly distributed keeping the original shape of carbon nanofibers. The hydrogen gas sensing time and sensitivity were improved based on effects of high specific surface area, micropore structure and deposited Pt catalyst.

• Journal of the Korea Convergence Society
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• v.10 no.1
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• pp.285-290
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• 2019

AHR regulates the expression of xenobiotics metabolizing enzymes (XMEs) as a transcription fact upon binding of ligands that are mainly aryl hydrocarbons. The role of AHR in human physiology has been intensively investigated for the past decades, however our understanding on AHR yet to be elucidated largely due to the lack of proper chemical agents. It has been demonstrated that AHR correlates to pathogenesis for some diseases in recent studies suggesting that the study on the AHR may provide a valid therapeutic target. Classical antagonists in current use are reported to be partially agonistic whereas a pure antagonist is yet to be found. In this study, phenyldiazenylaniline has been designed based on the structure of two known AHR antagonist, Resveratrol and CH223191. The derivatives of phenyldiazenylaniline have been prepared and subjected to assessment as an AHR antagonist in order to optimize the AHR antagonistic activity of the designed structure by means of convergence study of organic synthesis and molecular biology.

• Polymer(Korea)
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• v.36 no.3
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• pp.321-325
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• 2012

In this work, we prepared the activated graphite nanofibers (A-GNFs) via chemical activation with KOH/GNFs ratios in a range of 0 to 5. The effect of KOH activation was studied in the surface and pore properties of the samples for electrochemical performance. The surface properties of A-GNFs were characterized by XRD and SEM measurements. The textural properties of the A-GNFs were investigated by $N_2$/77 K adsorption isotherms using Brunauer-Emmett-Teller (BET) equation. Their electrochemical behaviors were investigated by cyclic voltammetry and galvanostatic charge-discharge performance. From the results, electrochemical performances of the A-GNFs were improved with increasing the ratio of KOH reagent. It was found that specific surface area and total pore volume of the A-GNFs were increased by KOH activation.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.307-312
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• 2017

In this study, the electrochemical performance of surface modified carbon using the PFO (pyrolyzed fuel oil) was investigated by chemical activation with KOH and $K_2CO_3$. PFO was heat treated at $390{\sim}400^{\circ}C$ for 1~3h to prepared the pitch. Three carbon precursors (pitch) prepared by the thermal reaction were 3903 (at $390^{\circ}C$ for 3h), 4001(at $400^{\circ}C$ for 1h) and 4002 (at $400^{\circ}C$ for 2h). Also, the effect of chemical activation catalysts and mixing time on the development of porosity during carbonization was investigated. The prepared carbon was analyzed by BET and FE-SEM. It was shown that chemical activation with KOH could be successfully used to develop carbon with specific surface area ($3.12m^2/g$) and mean pore size (22 nm). The electrochemical characteristics of modified carbon as the anode were investigated by constant current charge/discharge, cyclic voltammetry and electrochemical impedance tests. The coin cell using pitch (4002) modified by KOH has better initial capacity (318 mAh/g) than that of other pitch coin cells. Also, this prepared carbon anode appeared a high initial efficiency of 80% and the retention rate capability of 2C/0.1 C was 92%. It is found that modified carbon anode showed improved cycling and rate capacity performance.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.02a
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• pp.80-80
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• 1999

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1037-1044
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• 2000

The objective of this study is the preparation of activated carbon for BAC(biological activated carbon). Prepared activated carbon was measured iodine adsorption(mg/g). methylene blue adsorption(mg/g), B.E.T($m^2/g$), PSD(Pore Size Distribution) and 'Picabiol' which in commercial activated carbon for BAC. Activation method for this study was a chemical activation used the phosphoric acid. In the method, two important factors affected activation characterized in preparation were temperature and impregnated phosphoric acid concentration. Activation temperature and impregnated phosphoric acid concentration were changed the $600{\sim}800^{\circ}C$ and 35~50wt% respectively. Activation time was fixed for 3 hour. Optimal activation temperature was $800^{\circ}C$ and impregnated phosphoric acid concentrations was about 50wt%. By the above condition specific surface area, iodine adsorption number and methylene blue adsorption number resulted $1643.3m^2/g$, 1093 mg/g, 445.6 mg/g, respectively.

• Journal of the Korean Chemical Society
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• v.33 no.6
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• pp.582-587
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• 1989

Rates for aquation of $[Cr(NH_3)_5(DMF)]^{3+}$ ion in aqueous acidic solution have been measured by spectrophotometric method at various temperatures and pressures. The volume of activation for the aquation is small negative and lies in the limited range -2.76 ∼ -3.65 $cm^3mol^{-1}$. The entropy and compressibility coefficient of activation are small negative values. From the results of thermodynamic activation parameters, it can be inferred that the aquation of $[Cr(NH_3)_5(DMF)]^{3+}$ ion proceeds through an associative interchange($I_a$) mechanism.

• Journal of Digital Convergence
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• v.17 no.1
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• pp.443-447
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• 2019

Aryl hydrocarbon receptor (AhR) is the master regulator of xenobiotics metabolizing enzymes (XMEs). AhR is activated by aryl hydrocarbons upon binding then goes into the cell nucleus and acts as a transcription factor. Despite the role of AhR in human physiology has been investigated for a long while, it is yet to be understood mainly due to the lack of appropriate chemical agents. Furthermore, it has been reported that AhR is related to a wide range of pathogenesis. In addition, recent studies suggest that the study on the development of AhR antagonist may provide a valid therapeutic agent. Some known antagonists in current use are partially agonistic whereas a pure antagonist is still absent. In this study, two phenyl-ring structures of phenyldiazenylphenylpicolinamide has been modified into various structures and evaluated its impact on the AhR antagonistic activity to elucidate the structure-activity relationship.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.509-515
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• 1998

Activated coffee chars were prepared from coffee waste by chemical activation with zinc chloride. In this study, the following processes were carried out ; roasting step, carbonization step, chemical activation step, and washing and drying step. The roasting step of coffee waste was carried out at $300{\sim}400^{\circ}C$ for 10 minutes. The optimum condition of carbonization was at $650^{\circ}C$ for 1 hour. The most important parameter in chemical activation of coffee char was found to be the chemical ratio of activation agents. Activated coffee chars prepared by various activation methods were characterized in terms of the nitrogen BET surface area, the BJH pore volume and pore size distribution at 77 K. The $N_2$-BET surface areas and total pore volume of coffee chars prepared by the chemical activation with $ZnCl_2$ were determined as about $1110{\sim}1580m^2/g$ and $0.51{\sim}0.81cm^3/g$, respectively. Scanning Electron Microscopy (SEM) was used to observe the porosity and surface of activated coffee chars. From the results of SEM analysis, it was shown that active surface and many pores were formed after the chemical activation. The preparation of the activated coffee char from coffee waste was successfully carried out, which previews a possibility for exploitation of resources by recycling the waste.